chore: bump version to 3.1.3+62

- Add GetExtendedMetadataByISRC function in deezer.go
  - Searches track by ISRC then fetches album extended metadata
- Call enrichment in DownloadWithExtensionFallback before built-in download
  - Only enriches if genre/label are empty and ISRC is available
  - Logs enrichment results for debugging

.github/FUNDING.yml

@@ -0,0 +1 @@
+ko_fi: zarzet

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,123 @@
+name: Bug Report
+description: Report a bug or unexpected behavior
+title: "[Bug]: "
+labels: ["bug"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for taking the time to report a bug! Please fill out the form below.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      description: Please confirm the following before submitting
+      options:
+        - label: I have searched existing issues and this bug hasn't been reported yet
+          required: true
+        - label: I am using the latest version of SpotiFLAC (Stable Version)
+          required: true
+
+  - type: textarea
+    id: description
+    attributes:
+      label: Bug Description
+      description: A clear and concise description of what the bug is
+      placeholder: Describe the bug...
+    validations:
+      required: true
+
+  - type: textarea
+    id: steps
+    attributes:
+      label: Steps to Reproduce
+      description: Steps to reproduce the behavior
+      placeholder: |
+        1. Go to '...'
+        2. Click on '...'
+        3. See error
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected Behavior
+      description: What did you expect to happen?
+      placeholder: Describe what you expected...
+    validations:
+      required: true
+
+  - type: textarea
+    id: actual
+    attributes:
+      label: Actual Behavior
+      description: What actually happened?
+      placeholder: Describe what actually happened...
+    validations:
+      required: true
+
+  - type: input
+    id: version
+    attributes:
+      label: App Version
+      description: Which version of SpotiFLAC are you using? (Check in Settings > About)
+      placeholder: "e.g., v2.2.0"
+    validations:
+      required: true
+
+  - type: dropdown
+    id: platform
+    attributes:
+      label: Platform
+      description: Which platform are you using?
+      options:
+        - Android
+        - iOS
+    validations:
+      required: true
+
+  - type: input
+    id: device
+    attributes:
+      label: Device & OS Version
+      description: What device and OS version are you using?
+      placeholder: "e.g., Samsung Galaxy S24, Android 14"
+    validations:
+      required: true
+
+  - type: dropdown
+    id: download-service
+    attributes:
+      label: Download Service
+      description: Which download service were you using when the bug occurred?
+      options:
+        - Tidal
+        - Qobuz
+        - Amazon Music
+        - Deezer (search only)
+        - Not applicable
+    validations:
+      required: true
+
+  - type: textarea
+    id: logs
+    attributes:
+      label: Logs / Screenshots
+      description: |
+        If applicable, add logs or screenshots to help explain your problem.
+        
+        **To get logs:**
+        1. Go to Settings > Options > Detailed Logging (turn ON)
+        2. Reproduce the bug
+        3. Go to Settings > Logs
+        4. Tap Share button to export logs
+      placeholder: Paste logs or drag & drop screenshots here...
+
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional Context
+      description: Any other context about the problem
+      placeholder: Add any other context...

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+  - name: README
+    url: https://github.com/zarzet/SpotiFLAC-Mobile#readme
+    about: Check the README for setup instructions and FAQ
+  - name: Extension Development Guide
+    url: https://zarz.moe/docs
+    about: Documentation for building SpotiFLAC extensions

.github/ISSUE_TEMPLATE/download_issue.yml

@@ -0,0 +1,111 @@
+name: Download Issue
+description: Report issues with downloading specific tracks or albums
+title: "[Download]: "
+labels: ["download-issue"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Having trouble downloading a specific track or album? Please provide details below.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      description: Please confirm the following before submitting
+      options:
+        - label: I have tried downloading with a different service (Tidal/Qobuz/Amazon)
+          required: true
+        - label: I am using the latest version of SpotiFLAC (Stable Version)
+          required: true
+
+  - type: dropdown
+    id: issue-type
+    attributes:
+      label: Issue Type
+      description: What kind of download issue are you experiencing?
+      options:
+        - Track not found on service
+        - Wrong track downloaded
+        - Download fails/errors
+        - Metadata incorrect
+        - Audio quality issue
+        - Other
+    validations:
+      required: true
+
+  - type: input
+    id: spotify-url
+    attributes:
+      label: Spotify URL
+      description: The Spotify URL of the track/album you're trying to download
+      placeholder: "https://open.spotify.com/track/..."
+    validations:
+      required: true
+
+  - type: input
+    id: track-info
+    attributes:
+      label: Track Info
+      description: Artist name and track title
+      placeholder: "Artist - Track Title"
+    validations:
+      required: true
+
+  - type: dropdown
+    id: download-service
+    attributes:
+      label: Download Service
+      description: Which service did you try to download from?
+      options:
+        - Tidal
+        - Qobuz
+        - Amazon Music
+        - All services
+    validations:
+      required: true
+
+  - type: dropdown
+    id: search-service
+    attributes:
+      label: Search Service
+      description: Which search service are you using?
+      options:
+        - Spotify
+        - Deezer
+    validations:
+      required: true
+
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: Describe the issue in detail
+      placeholder: |
+        What happened? What did you expect?
+        If wrong track was downloaded, what track was downloaded instead?
+    validations:
+      required: true
+
+  - type: input
+    id: version
+    attributes:
+      label: App Version
+      description: Which version of SpotiFLAC are you using?
+      placeholder: "e.g., v2.2.0"
+    validations:
+      required: true
+
+  - type: textarea
+    id: screenshots
+    attributes:
+      label: Screenshots / Logs
+      description: |
+        If applicable, add screenshots or logs.
+        
+        **To get logs:**
+        1. Go to Settings > Options > Detailed Logging (turn ON)
+        2. Try downloading the track again
+        3. Go to Settings > Logs
+        4. Tap Share button to export logs
+      placeholder: Drag & drop screenshots or paste logs here...

.github/ISSUE_TEMPLATE/extension_feature_request.yml

@@ -0,0 +1,117 @@
+name: Extension API Feature Request
+description: Request new API features or capabilities for extension development
+title: "[Extension API]: "
+labels: ["enhancement", "extension-api"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for helping improve the SpotiFLAC Extension API! 
+        This form is for extension developers who need new features or capabilities that don't exist yet.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      description: Please confirm the following before submitting
+      options:
+        - label: I have read the [Extension Development Guide](https://github.com/zarzet/SpotiFLAC-Mobile/blob/main/docs/EXTENSION_DEVELOPMENT.md)
+          required: true
+        - label: I have searched existing issues and this API feature hasn't been requested yet
+          required: true
+
+  - type: textarea
+    id: extension_goal
+    attributes:
+      label: What are you trying to build?
+      description: Describe the extension or feature you're developing
+      placeholder: "I'm building an extension that downloads from [service name] / provides metadata from [source]..."
+    validations:
+      required: true
+
+  - type: textarea
+    id: current_limitation
+    attributes:
+      label: Current API Limitation
+      description: What's missing or limiting in the current extension API?
+      placeholder: |
+        The current API doesn't support:
+        - [missing feature 1]
+        - [missing feature 2]
+        
+        This prevents me from...
+    validations:
+      required: true
+
+  - type: textarea
+    id: proposed_api
+    attributes:
+      label: Proposed API / Feature
+      description: Describe the API or feature you'd like to see added
+      placeholder: |
+        I would like to have:
+        - A new function `api.newFeature()` that does X
+        - A new manifest field `newOption` that enables Y
+        - Access to Z capability...
+    validations:
+      required: true
+
+  - type: textarea
+    id: use_case
+    attributes:
+      label: Use Case Example
+      description: Provide a code example of how you would use this feature
+      placeholder: |
+        ```javascript
+        // Example usage in extension code
+        function download(request, progressCallback) {
+          const result = api.proposedFeature(params);
+          // ...
+        }
+        ```
+    validations:
+      required: false
+
+  - type: dropdown
+    id: api_category
+    attributes:
+      label: API Category
+      description: What category does this feature fall under?
+      options:
+        - HTTP/Network API
+        - File System API
+        - Storage API
+        - FFmpeg/Audio Processing
+        - Manifest Options
+        - Runtime Functions
+        - UI Integration
+        - Authentication
+        - Other
+    validations:
+      required: true
+
+  - type: dropdown
+    id: priority
+    attributes:
+      label: How critical is this for your extension?
+      options:
+        - Blocker - Cannot build my extension without this
+        - High - Major functionality depends on this
+        - Medium - Would significantly improve my extension
+        - Low - Nice to have
+    validations:
+      required: true
+
+  - type: textarea
+    id: workaround
+    attributes:
+      label: Current Workaround
+      description: Are you using any workaround currently? If so, describe it.
+      placeholder: "Currently I'm working around this by..."
+
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional Context
+      description: Add any other context, links to similar APIs, or examples from other platforms
+      placeholder: "Similar feature in other platforms: ..."

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,66 @@
+name: Feature Request
+description: Suggest a new feature or improvement
+title: "[Feature]: "
+labels: ["enhancement"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for suggesting a feature! Please fill out the form below.
+
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      description: Please confirm the following before submitting
+      options:
+        - label: I have searched existing issues and this feature hasn't been requested yet
+          required: true
+
+  - type: textarea
+    id: problem
+    attributes:
+      label: Problem / Motivation
+      description: Is your feature request related to a problem? Please describe.
+      placeholder: "A clear description of what the problem is. Ex: I'm always frustrated when..."
+    validations:
+      required: true
+
+  - type: textarea
+    id: solution
+    attributes:
+      label: Proposed Solution
+      description: Describe the solution you'd like
+      placeholder: A clear description of what you want to happen...
+    validations:
+      required: true
+
+  - type: textarea
+    id: alternatives
+    attributes:
+      label: Alternatives Considered
+      description: Describe any alternative solutions or features you've considered
+      placeholder: Other approaches you've thought about...
+
+  - type: dropdown
+    id: category
+    attributes:
+      label: Category
+      description: What category does this feature fall under?
+      options:
+        - UI/UX Improvement
+        - Download Feature
+        - New Service Integration
+        - Metadata/Tagging
+        - Performance
+        - Settings/Configuration
+        - Other
+    validations:
+      required: true
+
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional Context
+      description: Add any other context, mockups, or screenshots about the feature request
+      placeholder: Add any other context or screenshots...

.github/workflows/release.yml

@@ -93,11 +93,12 @@ jobs:
           # Accept licenses
           yes | $ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager --licenses || true
 
-          # Install NDK (required for gomobile)
+          # Install NDK r27d LTS (required for 16KB page size support on Android 15+)
-          $ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager "ndk;25.2.9519653" "platforms;android-34" "build-tools;34.0.0"
+          # Platform android-36 and build-tools 36.0.0 for targetSdk 36 (Android 16)
+          $ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager "ndk;27.3.13750724" "platforms;android-36" "build-tools;36.0.0"
 
           # Set NDK path
-          echo "ANDROID_NDK_HOME=$ANDROID_HOME/ndk/25.2.9519653" >> $GITHUB_ENV
+          echo "ANDROID_NDK_HOME=$ANDROID_HOME/ndk/27.3.13750724" >> $GITHUB_ENV
 
       - name: Install gomobile
         run: |
@@ -144,7 +145,7 @@ jobs:
           keyStorePassword: ${{ secrets.KEYSTORE_PASSWORD }}
           keyPassword: ${{ secrets.KEY_PASSWORD }}
         env:
-          BUILD_TOOLS_VERSION: "34.0.0"
+          BUILD_TOOLS_VERSION: "36.0.0"
 
       - name: Rename APKs
         run: |
@@ -344,6 +345,8 @@ jobs:
             CHANGELOG="See CHANGELOG.md for details."
           else
             echo "Found changelog content"
+            # Remove trailing --- separator if present (CHANGELOG uses --- between versions)
+            CHANGELOG=$(echo "$CHANGELOG" | sed '/^---$/d')
           fi
 
           # Save to file for multiline support

.gitignore

@@ -6,6 +6,8 @@ Thumbs.db
 .idea/
 .vscode/
 *.iml
+.cursorignore
+.cursorrules
 
 # Kiro specs (development only)
 .kiro/
@@ -13,6 +15,9 @@ Thumbs.db
 # Reference folder (development only)
 referensi/
 
+# Documentation (development only, published separately)
+docs/
+
 # Old spotiflac_android folder (moved to root)
 spotiflac_android/
 
@@ -50,3 +55,20 @@ ios/.symlinks/
 ios/Flutter/Flutter.framework/
 ios/Flutter/Flutter.podspec
 android/app/libs/gobackend-sources.jar
+
+# Extension folder
+extension/
+
+# Agent instructions
+AGENTS.md
+
+# Temp/misc
+nul
+
+# Log files
+*.log
+hs_err_*.log
+flutter_*.log
+
+# Development tools
+tool/

CODE_OF_CONDUCT.md

@@ -0,0 +1,133 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone, regardless of age, body
+size, visible or invisible disability, ethnicity, sex characteristics, gender
+identity and expression, level of experience, education, socio-economic status,
+nationality, personal appearance, race, caste, color, religion, or sexual
+identity and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming,
+diverse, inclusive, and healthy community.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment for our
+community include:
+
+* Demonstrating empathy and kindness toward other people
+* Being respectful of differing opinions, viewpoints, and experiences
+* Giving and gracefully accepting constructive feedback
+* Accepting responsibility and apologizing to those affected by our mistakes,
+  and learning from the experience
+* Focusing on what is best not just for us as individuals, but for the overall
+  community
+
+Examples of unacceptable behavior include:
+
+* The use of sexualized language or imagery, and sexual attention or advances of
+  any kind
+* Trolling, insulting or derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or email address,
+  without their explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Enforcement Responsibilities
+
+Community leaders are responsible for clarifying and enforcing our standards of
+acceptable behavior and will take appropriate and fair corrective action in
+response to any behavior that they deem inappropriate, threatening, offensive,
+or harmful.
+
+Community leaders have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct, and will communicate reasons for moderation
+decisions when appropriate.
+
+## Scope
+
+This Code of Conduct applies within all community spaces, and also applies when
+an individual is officially representing the community in public spaces.
+Examples of representing our community include using an official email address,
+posting via an official social media account, or acting as an appointed
+representative at an online or offline event.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported to the community leaders responsible for enforcement at
+**[zarzet](https://github.com/zarzet)**.
+
+All complaints will be reviewed and investigated promptly and fairly.
+
+All community leaders are obligated to respect the privacy and security of the
+reporter of any incident.
+
+## Enforcement Guidelines
+
+Community leaders will follow these Community Impact Guidelines in determining
+the consequences for any action they deem in violation of this Code of Conduct:
+
+### 1. Correction
+
+**Community Impact**: Use of inappropriate language or other behavior deemed
+unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from community leaders, providing
+clarity around the nature of the violation and an explanation of why the
+behavior was inappropriate. A public apology may be requested.
+
+### 2. Warning
+
+**Community Impact**: A violation through a single incident or series of
+actions.
+
+**Consequence**: A warning with consequences for continued behavior. No
+interaction with the people involved, including unsolicited interaction with
+those enforcing the Code of Conduct, for a specified period of time. This
+includes avoiding interactions in community spaces as well as external channels
+like social media. Violating these terms may lead to a temporary or permanent
+ban.
+
+### 3. Temporary Ban
+
+**Community Impact**: A serious violation of community standards, including
+sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public
+communication with the community for a specified period of time. No public or
+private interaction with the people involved, including unsolicited interaction
+with those enforcing the Code of Conduct, is allowed during this period.
+Violating these terms may lead to a permanent ban.
+
+### 4. Permanent Ban
+
+**Community Impact**: Demonstrating a pattern of violation of community
+standards, including sustained inappropriate behavior, harassment of an
+individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within the
+community.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 2.1, available at
+[https://www.contributor-covenant.org/version/2/1/code_of_conduct.html][v2.1].
+
+Community Impact Guidelines were inspired by
+[Mozilla's code of conduct enforcement ladder][Mozilla CoC].
+
+For answers to common questions about this code of conduct, see the FAQ at
+[https://www.contributor-covenant.org/faq][FAQ]. Translations are available at
+[https://www.contributor-covenant.org/translations][translations].
+
+[homepage]: https://www.contributor-covenant.org
+[v2.1]: https://www.contributor-covenant.org/version/2/1/code_of_conduct.html
+[Mozilla CoC]: https://github.com/mozilla/diversity
+[FAQ]: https://www.contributor-covenant.org/faq
+[translations]: https://www.contributor-covenant.org/translations

CONTRIBUTING.md

@@ -0,0 +1,268 @@
+# Contributing to SpotiFLAC
+
+First off, thank you for considering contributing to SpotiFLAC! 🎉
+
+This document provides guidelines and steps for contributing. Following these guidelines helps maintain code quality and ensures a smooth collaboration process.
+
+## Table of Contents
+
+- [Code of Conduct](#code-of-conduct)
+- [How Can I Contribute?](#how-can-i-contribute)
+  - [Reporting Bugs](#reporting-bugs)
+  - [Suggesting Features](#suggesting-features)
+  - [Code Contributions](#code-contributions)
+  - [Translations](#translations)
+- [Development Setup](#development-setup)
+- [Project Structure](#project-structure)
+- [Coding Guidelines](#coding-guidelines)
+- [Commit Guidelines](#commit-guidelines)
+- [Pull Request Process](#pull-request-process)
+
+## Code of Conduct
+
+This project and everyone participating in it is governed by our [Code of Conduct](CODE_OF_CONDUCT.md). By participating, you are expected to uphold this code. Please report unacceptable behavior to the project maintainers.
+
+## How Can I Contribute?
+
+### Reporting Bugs
+
+Before creating bug reports, please check the [existing issues](https://github.com/zarzet/SpotiFLAC-Mobile/issues) to avoid duplicates.
+
+When creating a bug report, please use the bug report template and include:
+
+- **Clear and descriptive title**
+- **Steps to reproduce** the issue
+- **Expected behavior** vs **actual behavior**
+- **Screenshots or screen recordings** if applicable
+- **Device information** (model, OS version)
+- **App version**
+- **Logs** from Settings > About > View Logs
+
+### Suggesting Features
+
+Feature requests are welcome! Please use the feature request template and:
+
+- **Check existing issues** to avoid duplicates
+- **Describe the feature** clearly
+- **Explain the use case** - why would this be useful?
+- **Consider the scope** - is this a small enhancement or a major feature?
+
+### Code Contributions
+
+1. **Fork the repository** and create your branch from `dev`
+2. **Make your changes** following our coding guidelines
+3. **Test your changes** thoroughly
+4. **Submit a pull request** to the `dev` branch
+
+### Translations
+
+We use [Crowdin](https://crowdin.com/project/spotiflac-mobile) for translations. To contribute:
+
+1. Visit our [Crowdin project](https://crowdin.com/project/spotiflac-mobile)
+2. Select your language or request a new one
+3. Start translating!
+
+Translation files are located in `lib/l10n/arb/`.
+
+## Development Setup
+
+### Prerequisites
+
+- **Flutter SDK** 3.10.0 or higher
+- **Dart SDK** 3.10.0 or higher
+- **Android Studio** or **VS Code** with Flutter extensions
+- **Git**
+
+### Getting Started
+
+1. **Clone your fork**
+   ```bash
+   git clone https://github.com/YOUR_USERNAME/SpotiFLAC-Mobile.git
+   cd SpotiFLAC-Mobile
+   ```
+
+2. **Add upstream remote**
+   ```bash
+   git remote add upstream https://github.com/zarzet/SpotiFLAC-Mobile.git
+   ```
+
+3. **Install dependencies**
+   ```bash
+   flutter pub get
+   ```
+
+4. **Generate code** (for Riverpod, JSON serialization, etc.)
+   ```bash
+   dart run build_runner build --delete-conflicting-outputs
+   ```
+
+5. **Run the app**
+   ```bash
+   flutter run
+   ```
+
+### Building
+
+```bash
+# Debug build
+flutter build apk --debug
+
+# Release build
+flutter build apk --release
+```
+
+## Project Structure
+
+```
+lib/
+├── l10n/               # Localization files
+│   └── arb/            # ARB translation files
+├── models/             # Data models
+├── providers/          # Riverpod providers
+├── screens/            # UI screens
+│   └── settings/       # Settings sub-screens
+├── services/           # Business logic services
+├── theme/              # App theming
+├── utils/              # Utility functions
+├── widgets/            # Reusable widgets
+├── app.dart            # App configuration
+└── main.dart           # Entry point
+```
+
+## Coding Guidelines
+
+### General
+
+- Follow [Effective Dart](https://dart.dev/effective-dart) guidelines
+- Use meaningful variable and function names
+- Keep functions small and focused
+- Add comments for complex logic
+
+### Formatting
+
+- Use `dart format` before committing
+- Maximum line length: 80 characters
+- Use trailing commas for better formatting
+
+```bash
+dart format .
+```
+
+### Linting
+
+Ensure your code passes all lints:
+
+```bash
+flutter analyze
+```
+
+### State Management
+
+We use **Riverpod** for state management. Follow these patterns:
+
+```dart
+// Use code generation with riverpod_annotation
+@riverpod
+class MyNotifier extends _$MyNotifier {
+  @override
+  MyState build() => MyState();
+  
+  // Methods to update state
+}
+```
+
+### Localization
+
+All user-facing strings should be localized:
+
+```dart
+// Good
+Text(AppLocalizations.of(context)!.downloadComplete)
+
+// Bad
+Text('Download Complete')
+```
+
+To add new strings:
+1. Add the key to `lib/l10n/arb/app_en.arb`
+2. Run `flutter gen-l10n`
+
+## Commit Guidelines
+
+We follow [Conventional Commits](https://www.conventionalcommits.org/):
+
+```
+<type>(<scope>): <description>
+
+[optional body]
+
+[optional footer(s)]
+```
+
+### Types
+
+- `feat`: New feature
+- `fix`: Bug fix
+- `docs`: Documentation changes
+- `style`: Code style changes (formatting, etc.)
+- `refactor`: Code refactoring
+- `perf`: Performance improvements
+- `test`: Adding or updating tests
+- `chore`: Maintenance tasks
+
+### Examples
+
+```
+feat(download): add batch download support
+fix(ui): resolve overflow on small screens
+docs: update contributing guidelines
+chore(deps): update flutter_riverpod to 3.1.0
+```
+
+## Pull Request Process
+
+1. **Update your fork**
+   ```bash
+   git fetch upstream
+   git rebase upstream/dev
+   ```
+
+2. **Create a feature branch**
+   ```bash
+   git checkout -b feat/my-new-feature
+   ```
+
+3. **Make your changes** and commit following our guidelines
+
+4. **Push to your fork**
+   ```bash
+   git push origin feat/my-new-feature
+   ```
+
+5. **Create a Pull Request**
+   - Target the `dev` branch
+   - Fill in the PR template
+   - Link related issues
+
+6. **Address review feedback**
+   - Make requested changes
+   - Push additional commits
+   - Request re-review when ready
+
+### PR Requirements
+
+- [ ] Code follows project conventions
+- [ ] All tests pass
+- [ ] No new linting errors
+- [ ] Documentation updated (if needed)
+- [ ] Commit messages follow guidelines
+- [ ] PR description is clear and complete
+
+## Questions?
+
+If you have questions, feel free to:
+
+- Open a [Discussion](https://github.com/zarzet/SpotiFLAC-Mobile/discussions)
+- Check existing [Issues](https://github.com/zarzet/SpotiFLAC-Mobile/issues)
+
+Thank you for contributing! 💚

README.md

@@ -1,11 +1,12 @@
 [![GitHub All Releases](https://img.shields.io/github/downloads/zarzet/SpotiFLAC-Mobile/total?style=for-the-badge)](https://github.com/zarzet/SpotiFLAC-Mobile/releases)
-[![VirusTotal](https://img.shields.io/badge/VirusTotal-Safe-brightgreen?style=for-the-badge&logo=virustotal)](https://www.virustotal.com/gui/file/cb87d23fc9fd4a6f0a7b2b934773029c7e7ab25101dfce503e68e9c9e8921fca/)
+[![VirusTotal](https://img.shields.io/badge/VirusTotal-Safe-brightgreen?style=for-the-badge&logo=virustotal)](https://www.virustotal.com/gui/file/e1c527eacb6f5ce527af214a75aab8da060c2afc629825fff24af858439e7e6b)
+[![Crowdin](https://img.shields.io/badge/HELP%20TRANSLATE%20ON-CROWDIN-%2321252b?style=for-the-badge&logo=crowdin)](https://crowdin.com/project/spotiflac-mobile)
 
 <div align="center">
 
 <img src="icon.png" width="128" />
 
-Get Spotify tracks in true FLAC from Tidal, Qobuz & Amazon Music — no account required.
+Download music in true lossless FLAC from Tidal, Qobuz & Amazon Music — no account required.
 
 ![Android](https://img.shields.io/badge/Android-7.0%2B-3DDC84?style=for-the-badge&logo=android&logoColor=white)
 ![iOS](https://img.shields.io/badge/iOS-14.0%2B-000000?style=for-the-badge&logo=apple&logoColor=white)
@@ -23,37 +24,60 @@ Get Spotify tracks in true FLAC from Tidal, Qobuz & Amazon Music — no account
   <img src="assets/images/4.jpg?v=2" width="200" />
 </p>
 
-## Metadata Source
+## Search Source
 
-SpotiFLAC supports two metadata sources for searching tracks:
+SpotiFLAC supports multiple search sources for finding music metadata:
 
-| Source | Pros | Cons |
+| Source | Setup |
-|--------|------|------|
+|--------|-------|
-| **Deezer** (Default) | No developer account needed, rate limit per user IP | Slightly less comprehensive catalog |
+| **Deezer** (Default) | No setup required |
-| **Spotify** | More comprehensive catalog, better search results | Requires developer API credentials to avoid rate limiting |
+| **Extensions** | Install additional search providers from the Store |
 
-### Using Spotify
+## Extensions
-To use Spotify as your search source without hitting rate limits:
+
-1. Create a Spotify Developer account at [developer.spotify.com](https://developer.spotify.com)
+Extensions allow the community to add new music sources and features without waiting for app updates. When a streaming service API changes or a new source becomes available, extensions can be updated independently.
-2. Create an app to get your Client ID and Client Secret
+
-3. Go to **Settings > Options > Spotify API > Change from Deezer to Spotify > Input Custom Credentials**
+### Installing Extensions
-4. Enter your Client ID and Secret
+1. Go to **Store** tab in the app
-5. Change **Search Source** to Spotify
+2. Browse and install extensions with one tap
+3. Or download a `.spotiflac-ext` file and install manually via **Settings > Extensions**
+4. Configure extension settings if needed
+5. Set provider priority in **Settings > Extensions > Provider Priority**
+
+### Developing Extensions
+Want to create your own extension? Check out the [Extension Development Guide](https://zarz.moe/docs) for complete documentation.
 
 ## Other project
 
 ### [SpotiFLAC (Desktop)](https://github.com/afkarxyz/SpotiFLAC)
-Get Spotify tracks in true FLAC from Tidal, Qobuz & Amazon Music for Windows, macOS & Linux
+Download music in true lossless FLAC from Tidal, Qobuz & Amazon Music for Windows, macOS & Linux
+
+## FAQ
+
+**Q: Why is my download failing with "Song not found"?**  
+A: The track may not be available on Tidal, Qobuz, or Amazon Music. Try enabling more download services in Settings > Download > Provider Priority, or install additional extensions from the Store.
+
+**Q: Why are some tracks downloading in lower quality?**  
+A: Quality depends on what's available from the streaming service. Tidal offers up to 24-bit/192kHz, Qobuz up to 24-bit/192kHz, and Amazon up to 24-bit/48kHz. The app automatically selects the best available quality.
+
+**Q: Can I download playlists?**  
+A: Yes! Just paste the playlist URL in the search bar. The app will fetch all tracks and queue them for download.
+
+**Q: Why do I need to grant storage permission?**  
+A: The app needs permission to save downloaded files to your device. On Android 13+, you may need to grant "All files access" in Settings > Apps > SpotiFLAC > Permissions.
+
+**Q: Is this app safe?**  
+A: Yes, the app is open source and you can verify the code yourself. Each release is scanned with VirusTotal (see badge at top of README).
 
 [![Ko-fi](https://img.shields.io/badge/Ko--fi-Support%20Me-FF5E5B?style=for-the-badge&logo=ko-fi&logoColor=white)](https://ko-fi.com/zarzet)
 
 ## Disclaimer
 
-> **iOS Support**: This app is primarily tested on Android. iOS support is experimental and may have bugs — the developer is too poor to afford an iPhone for proper testing. If you encounter issues on iOS, please report them!
-
 This project is for **educational and private use only**. The developer does not condone or encourage copyright infringement.
 
-**SpotiFLAC** is a third-party tool and is not affiliated with, endorsed by, or connected to Spotify, Tidal, Qobuz, Amazon Music, or any other streaming service.
+**SpotiFLAC** is a third-party tool and is not affiliated with, endorsed by, or connected to Tidal, Qobuz, Amazon Music, Deezer, or any other streaming service.
+
+The application is purely a user interface that facilitates communication between your device and existing third-party services.
 
 You are solely responsible for:
 1. Ensuring your use of this software complies with your local laws.

android/app/build.gradle.kts

@@ -46,7 +46,7 @@ android {
     defaultConfig {
         applicationId = "com.zarz.spotiflac"
         minSdk = flutter.minSdkVersion
-        targetSdk = 34
+        targetSdk = 36
         versionCode = flutter.versionCode
         versionName = flutter.versionName
         multiDexEnabled = true

android/app/src/main/kotlin/com/zarz/spotiflac/DownloadService.kt

@@ -15,6 +15,9 @@ import androidx.core.app.NotificationCompat
 /**
  * Foreground service to keep downloads running when app is in background.
  * This prevents Android from killing the download process or throttling network.
+ * 
+ * Note: Android 15+ (API 35+) has a 6-hour timeout for dataSync foreground services.
+ * The service will be stopped automatically after 6 hours of cumulative runtime in 24 hours.
  */
 class DownloadService : Service() {
     
@@ -106,6 +109,19 @@ class DownloadService : Service() {
     
     override fun onBind(intent: Intent?): IBinder? = null
     
+    /**
+     * Called when the foreground service timeout is reached (Android 15+, API 35+).
+     * dataSync services have a 6-hour limit in a 24-hour period.
+     * We must call stopSelf() within a few seconds to avoid a crash.
+     */
+    override fun onTimeout(startId: Int, fgsType: Int) {
+        // Log the timeout for debugging
+        android.util.Log.w("DownloadService", "Foreground service timeout reached (6 hours limit). Stopping service.")
+        
+        // Gracefully stop the service
+        stopForegroundService()
+    }
+    
     private fun createNotificationChannel() {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             val channel = NotificationChannel(

android/app/src/main/kotlin/com/zarz/spotiflac/MainActivity.kt

@@ -117,6 +117,13 @@ class MainActivity: FlutterActivity() {
                             }
                             result.success(null)
                         }
+                        "cancelDownload" -> {
+                            val itemId = call.argument<String>("item_id") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.cancelDownload(itemId)
+                            }
+                            result.success(null)
+                        }
                         "setDownloadDirectory" -> {
                             val path = call.argument<String>("path") ?: ""
                             withContext(Dispatchers.IO) {
@@ -151,8 +158,9 @@ class MainActivity: FlutterActivity() {
                             val spotifyId = call.argument<String>("spotify_id") ?: ""
                             val trackName = call.argument<String>("track_name") ?: ""
                             val artistName = call.argument<String>("artist_name") ?: ""
+                            val durationMs = call.argument<Int>("duration_ms")?.toLong() ?: 0L
                             val response = withContext(Dispatchers.IO) {
-                                Gobackend.fetchLyrics(spotifyId, trackName, artistName)
+                                Gobackend.fetchLyrics(spotifyId, trackName, artistName, durationMs)
                             }
                             result.success(response)
                         }
@@ -161,8 +169,9 @@ class MainActivity: FlutterActivity() {
                             val trackName = call.argument<String>("track_name") ?: ""
                             val artistName = call.argument<String>("artist_name") ?: ""
                             val filePath = call.argument<String>("file_path") ?: ""
+                            val durationMs = call.argument<Int>("duration_ms")?.toLong() ?: 0L
                             val response = withContext(Dispatchers.IO) {
-                                Gobackend.getLyricsLRC(spotifyId, trackName, artistName, filePath)
+                                Gobackend.getLyricsLRC(spotifyId, trackName, artistName, filePath, durationMs)
                             }
                             result.success(response)
                         }
@@ -218,6 +227,12 @@ class MainActivity: FlutterActivity() {
                             }
                             result.success(null)
                         }
+                        "hasSpotifyCredentials" -> {
+                            val hasCredentials = withContext(Dispatchers.IO) {
+                                Gobackend.checkSpotifyCredentials()
+                            }
+                            result.success(hasCredentials)
+                        }
                         "preWarmTrackCache" -> {
                             val tracksJson = call.argument<String>("tracks") ?: "[]"
                             withContext(Dispatchers.IO) {
@@ -269,6 +284,13 @@ class MainActivity: FlutterActivity() {
                             }
                             result.success(response)
                         }
+                        "getDeezerExtendedMetadata" -> {
+                            val trackId = call.argument<String>("track_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getDeezerExtendedMetadata(trackId)
+                            }
+                            result.success(response)
+                        }
                         "convertSpotifyToDeezer" -> {
                             val resourceType = call.argument<String>("resource_type") ?: ""
                             val spotifyId = call.argument<String>("spotify_id") ?: ""
@@ -284,6 +306,378 @@ class MainActivity: FlutterActivity() {
                             }
                             result.success(response)
                         }
+                        // Log methods
+                        "getLogs" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getLogs()
+                            }
+                            result.success(response)
+                        }
+                        "getLogsSince" -> {
+                            val index = call.argument<Int>("index") ?: 0
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getLogsSince(index.toLong())
+                            }
+                            result.success(response)
+                        }
+                        "clearLogs" -> {
+                            withContext(Dispatchers.IO) {
+                                Gobackend.clearLogs()
+                            }
+                            result.success(null)
+                        }
+                        "getLogCount" -> {
+                            val count = withContext(Dispatchers.IO) {
+                                Gobackend.getLogCount()
+                            }
+                            result.success(count.toInt())
+                        }
+                        "setLoggingEnabled" -> {
+                            val enabled = call.argument<Boolean>("enabled") ?: false
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setLoggingEnabled(enabled)
+                            }
+                            result.success(null)
+                        }
+                        // Extension System methods
+                        "initExtensionSystem" -> {
+                            val extensionsDir = call.argument<String>("extensions_dir") ?: ""
+                            val dataDir = call.argument<String>("data_dir") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.initExtensionSystem(extensionsDir, dataDir)
+                            }
+                            result.success(null)
+                        }
+                        "loadExtensionsFromDir" -> {
+                            val dirPath = call.argument<String>("dir_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.loadExtensionsFromDir(dirPath)
+                            }
+                            result.success(response)
+                        }
+                        "loadExtensionFromPath" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.loadExtensionFromPath(filePath)
+                            }
+                            result.success(response)
+                        }
+                        "unloadExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.unloadExtensionByID(extensionId)
+                            }
+                            result.success(null)
+                        }
+                        "removeExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.removeExtensionByID(extensionId)
+                            }
+                            result.success(null)
+                        }
+                        "upgradeExtension" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.upgradeExtensionFromPath(filePath)
+                            }
+                            result.success(response)
+                        }
+                        "checkExtensionUpgrade" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.checkExtensionUpgradeFromPath(filePath)
+                            }
+                            result.success(response)
+                        }
+                        "getInstalledExtensions" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getInstalledExtensions()
+                            }
+                            result.success(response)
+                        }
+                        "setExtensionEnabled" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val enabled = call.argument<Boolean>("enabled") ?: false
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setExtensionEnabledByID(extensionId, enabled)
+                            }
+                            result.success(null)
+                        }
+                        "setProviderPriority" -> {
+                            val priorityJson = call.argument<String>("priority") ?: "[]"
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setProviderPriorityJSON(priorityJson)
+                            }
+                            result.success(null)
+                        }
+                        "getProviderPriority" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getProviderPriorityJSON()
+                            }
+                            result.success(response)
+                        }
+                        "setMetadataProviderPriority" -> {
+                            val priorityJson = call.argument<String>("priority") ?: "[]"
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setMetadataProviderPriorityJSON(priorityJson)
+                            }
+                            result.success(null)
+                        }
+                        "getMetadataProviderPriority" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getMetadataProviderPriorityJSON()
+                            }
+                            result.success(response)
+                        }
+                        "getExtensionSettings" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getExtensionSettingsJSON(extensionId)
+                            }
+                            result.success(response)
+                        }
+                        "setExtensionSettings" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val settingsJson = call.argument<String>("settings") ?: "{}"
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setExtensionSettingsJSON(extensionId, settingsJson)
+                            }
+                            result.success(null)
+                        }
+                        "invokeExtensionAction" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val actionName = call.argument<String>("action") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.invokeExtensionActionJSON(extensionId, actionName)
+                            }
+                            result.success(response)
+                        }
+                        "searchTracksWithExtensions" -> {
+                            val query = call.argument<String>("query") ?: ""
+                            val limit = call.argument<Int>("limit") ?: 20
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.searchTracksWithExtensionsJSON(query, limit.toLong())
+                            }
+                            result.success(response)
+                        }
+                        "downloadWithExtensions" -> {
+                            val requestJson = call.arguments as String
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.downloadWithExtensionsJSON(requestJson)
+                            }
+                            result.success(response)
+                        }
+                        "removeExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.removeExtensionByID(extensionId)
+                            }
+                            result.success(null)
+                        }
+                        "cleanupExtensions" -> {
+                            withContext(Dispatchers.IO) {
+                                Gobackend.cleanupExtensions()
+                            }
+                            result.success(null)
+                        }
+                        // Extension Auth API methods
+                        "getExtensionPendingAuth" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getExtensionPendingAuthJSON(extensionId)
+                            }
+                            if (response.isNullOrEmpty()) {
+                                result.success(null)
+                            } else {
+                                result.success(response)
+                            }
+                        }
+                        "setExtensionAuthCode" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val authCode = call.argument<String>("auth_code") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setExtensionAuthCodeByID(extensionId, authCode)
+                            }
+                            result.success(null)
+                        }
+                        "setExtensionTokens" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val accessToken = call.argument<String>("access_token") ?: ""
+                            val refreshToken = call.argument<String>("refresh_token") ?: ""
+                            val expiresIn = call.argument<Int>("expires_in") ?: 0
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setExtensionTokensByID(extensionId, accessToken, refreshToken, expiresIn.toLong())
+                            }
+                            result.success(null)
+                        }
+                        "clearExtensionPendingAuth" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.clearExtensionPendingAuthByID(extensionId)
+                            }
+                            result.success(null)
+                        }
+                        "isExtensionAuthenticated" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val isAuth = withContext(Dispatchers.IO) {
+                                Gobackend.isExtensionAuthenticatedByID(extensionId)
+                            }
+                            result.success(isAuth)
+                        }
+                        "getAllPendingAuthRequests" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getAllPendingAuthRequestsJSON()
+                            }
+                            result.success(response)
+                        }
+                        // Extension FFmpeg API
+                        "getPendingFFmpegCommand" -> {
+                            val commandId = call.argument<String>("command_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getPendingFFmpegCommandJSON(commandId)
+                            }
+                            if (response.isNullOrEmpty()) {
+                                result.success(null)
+                            } else {
+                                result.success(response)
+                            }
+                        }
+                        "setFFmpegCommandResult" -> {
+                            val commandId = call.argument<String>("command_id") ?: ""
+                            val success = call.argument<Boolean>("success") ?: false
+                            val output = call.argument<String>("output") ?: ""
+                            val error = call.argument<String>("error") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.setFFmpegCommandResultByID(commandId, success, output, error)
+                            }
+                            result.success(null)
+                        }
+                        "getAllPendingFFmpegCommands" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getAllPendingFFmpegCommandsJSON()
+                            }
+                            result.success(response)
+                        }
+                        // Extension Custom Search API
+                        "customSearchWithExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val query = call.argument<String>("query") ?: ""
+                            val optionsJson = call.argument<String>("options") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.customSearchWithExtensionJSON(extensionId, query, optionsJson)
+                            }
+                            result.success(response)
+                        }
+                        "getSearchProviders" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getSearchProvidersJSON()
+                            }
+                            result.success(response)
+                        }
+                        // Extension URL Handler API
+                        "handleURLWithExtension" -> {
+                            val url = call.argument<String>("url") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.handleURLWithExtensionJSON(url)
+                            }
+                            result.success(response)
+                        }
+                        "findURLHandler" -> {
+                            val url = call.argument<String>("url") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.findURLHandlerJSON(url)
+                            }
+                            result.success(response)
+                        }
+                        "getURLHandlers" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getURLHandlersJSON()
+                            }
+                            result.success(response)
+                        }
+                        "getAlbumWithExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val albumId = call.argument<String>("album_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getAlbumWithExtensionJSON(extensionId, albumId)
+                            }
+                            result.success(response)
+                        }
+                        "getPlaylistWithExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val playlistId = call.argument<String>("playlist_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getPlaylistWithExtensionJSON(extensionId, playlistId)
+                            }
+                            result.success(response)
+                        }
+                        "getArtistWithExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val artistId = call.argument<String>("artist_id") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getArtistWithExtensionJSON(extensionId, artistId)
+                            }
+                            result.success(response)
+                        }
+                        // Extension Post-Processing API
+                        "runPostProcessing" -> {
+                            val filePath = call.argument<String>("file_path") ?: ""
+                            val metadataJson = call.argument<String>("metadata") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.runPostProcessingJSON(filePath, metadataJson)
+                            }
+                            result.success(response)
+                        }
+                        "getPostProcessingProviders" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getPostProcessingProvidersJSON()
+                            }
+                            result.success(response)
+                        }
+                        // Extension Store
+                        "initExtensionStore" -> {
+                            val cacheDir = call.argument<String>("cache_dir") ?: ""
+                            withContext(Dispatchers.IO) {
+                                Gobackend.initExtensionStoreJSON(cacheDir)
+                            }
+                            result.success(null)
+                        }
+                        "getStoreExtensions" -> {
+                            val forceRefresh = call.argument<Boolean>("force_refresh") ?: false
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getStoreExtensionsJSON(forceRefresh)
+                            }
+                            result.success(response)
+                        }
+                        "searchStoreExtensions" -> {
+                            val query = call.argument<String>("query") ?: ""
+                            val category = call.argument<String>("category") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.searchStoreExtensionsJSON(query, category)
+                            }
+                            result.success(response)
+                        }
+                        "getStoreCategories" -> {
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.getStoreCategoriesJSON()
+                            }
+                            result.success(response)
+                        }
+                        "downloadStoreExtension" -> {
+                            val extensionId = call.argument<String>("extension_id") ?: ""
+                            val destDir = call.argument<String>("dest_dir") ?: ""
+                            val response = withContext(Dispatchers.IO) {
+                                Gobackend.downloadStoreExtensionJSON(extensionId, destDir)
+                            }
+                            result.success(response)
+                        }
+                        "clearStoreCache" -> {
+                            withContext(Dispatchers.IO) {
+                                Gobackend.clearStoreCacheJSON()
+                            }
+                            result.success(null)
+                        }
                         else -> result.notImplemented()
                     }
                 } catch (e: Exception) {

build_assets/ffmpeg_service_ios.dart

@@ -42,17 +42,27 @@ class FFmpegServiceIOS {
   }
 
   /// Convert FLAC to MP3
-  static Future<String?> convertFlacToMp3(String inputPath, {String bitrate = '320k'}) async {
+  /// If deleteOriginal is true, deletes the FLAC file after conversion
-    final dir = File(inputPath).parent.path;
+  static Future<String?> convertFlacToMp3(
-    final baseName = inputPath.split(Platform.pathSeparator).last.replaceAll('.flac', '');
+    String inputPath, {
-    final outputDir = '$dir${Platform.pathSeparator}MP3';
+    String bitrate = '320k',
-    await Directory(outputDir).create(recursive: true);
+    bool deleteOriginal = true,
-    final outputPath = '$outputDir${Platform.pathSeparator}$baseName.mp3';
+  }) async {
+    // Convert in same folder, just change extension
+    final outputPath = inputPath.replaceAll('.flac', '.mp3');
 
     final command = '-i "$inputPath" -codec:a libmp3lame -b:a $bitrate -map 0:a -map_metadata 0 -id3v2_version 3 "$outputPath" -y';
     final result = await _execute(command);
 
-    if (result.success) return outputPath;
+    if (result.success) {
+      // Delete original FLAC if requested
+      if (deleteOriginal) {
+        try {
+          await File(inputPath).delete();
+        } catch (_) {}
+      }
+      return outputPath;
+    }
     _log.e('FLAC to MP3 conversion failed: ${result.output}');
     return null;
   }
@@ -177,6 +187,123 @@ class FFmpegServiceIOS {
     return null;
   }
 
+  /// Embed metadata and cover art to MP3 file using ID3v2 tags
+  /// Returns the file path on success, null on failure
+  static Future<String?> embedMetadataToMp3({
+    required String mp3Path,
+    String? coverPath,
+    Map<String, String>? metadata,
+  }) async {
+    final tempOutput = '$mp3Path.tmp';
+    
+    final StringBuffer cmdBuffer = StringBuffer();
+    cmdBuffer.write('-i "$mp3Path" ');
+    
+    if (coverPath != null) {
+      cmdBuffer.write('-i "$coverPath" ');
+    }
+    
+    cmdBuffer.write('-map 0:a ');
+    
+    if (coverPath != null) {
+      cmdBuffer.write('-map 1:0 ');
+      cmdBuffer.write('-c:v:0 copy ');
+      cmdBuffer.write('-id3v2_version 3 ');
+      cmdBuffer.write('-metadata:s:v title="Album cover" ');
+      cmdBuffer.write('-metadata:s:v comment="Cover (front)" ');
+    }
+    
+    cmdBuffer.write('-c:a copy ');
+    
+    if (metadata != null) {
+      // Convert FLAC/Vorbis tags to ID3v2 tags for MP3
+      final id3Metadata = _convertToId3Tags(metadata);
+      id3Metadata.forEach((key, value) {
+        final sanitizedValue = value.replaceAll('"', '\\"');
+        cmdBuffer.write('-metadata $key="$sanitizedValue" ');
+      });
+    }
+    
+    cmdBuffer.write('-id3v2_version 3 "$tempOutput" -y');
+    
+    final command = cmdBuffer.toString();
+    _log.d('Executing FFmpeg MP3 embed command: $command');
+
+    final result = await _execute(command);
+
+    if (result.success) {
+      try {
+        await File(mp3Path).delete();
+        await File(tempOutput).rename(mp3Path);
+        _log.d('MP3 metadata embedded successfully');
+        return mp3Path;
+      } catch (e) {
+        _log.e('Failed to replace MP3 file after metadata embed: $e');
+        return null;
+      }
+    }
+
+    try {
+      final tempFile = File(tempOutput);
+      if (await tempFile.exists()) {
+        await tempFile.delete();
+      }
+    } catch (_) {}
+
+    _log.e('MP3 Metadata/Cover embed failed: ${result.output}');
+    return null;
+  }
+
+  /// Convert FLAC/Vorbis comment tags to ID3v2 compatible tags
+  static Map<String, String> _convertToId3Tags(Map<String, String> vorbisMetadata) {
+    final id3Map = <String, String>{};
+    
+    for (final entry in vorbisMetadata.entries) {
+      final key = entry.key.toUpperCase();
+      final value = entry.value;
+      
+      // Map Vorbis comments to ID3v2 frame names
+      switch (key) {
+        case 'TITLE':
+          id3Map['title'] = value;
+          break;
+        case 'ARTIST':
+          id3Map['artist'] = value;
+          break;
+        case 'ALBUM':
+          id3Map['album'] = value;
+          break;
+        case 'ALBUMARTIST':
+          id3Map['album_artist'] = value;
+          break;
+        case 'TRACKNUMBER':
+        case 'TRACK':
+          id3Map['track'] = value;
+          break;
+        case 'DISCNUMBER':
+        case 'DISC':
+          id3Map['disc'] = value;
+          break;
+        case 'DATE':
+        case 'YEAR':
+          id3Map['date'] = value;
+          break;
+        case 'ISRC':
+          id3Map['TSRC'] = value; // ID3v2 ISRC frame
+          break;
+        case 'LYRICS':
+        case 'UNSYNCEDLYRICS':
+          id3Map['lyrics'] = value;
+          break;
+        default:
+          // Pass through other tags as-is
+          id3Map[key.toLowerCase()] = value;
+      }
+    }
+    
+    return id3Map;
+  }
+
   /// Check if FFmpeg is available
   static Future<bool> isAvailable() async {
     try {

crowdin.yml

@@ -0,0 +1,19 @@
+files:
+  - source: /lib/l10n/arb/app_en.arb
+    translation: /lib/l10n/arb/app_%locale%.arb
+    languages_mapping:
+      locale:
+        # Short codes for single-variant languages
+        de: de
+        es: es
+        fr: fr
+        hi: hi
+        id: id
+        ja: ja
+        ko: ko
+        nl: nl
+        pt: pt
+        ru: ru
+        # Full codes for Chinese variants
+        zh-CN: zh_CN
+        zh-TW: zh_TW

go_backend/amazon.go

@@ -2,8 +2,10 @@ package gobackend
 
 import (
 	"bufio"
+	"context"
 	"encoding/base64"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -15,20 +17,18 @@ import (
 	"time"
 )
 
-// AmazonDownloader handles Amazon Music downloads using DoubleDouble service (same as PC)
 type AmazonDownloader struct {
 	client           *http.Client
-	regions          []string  // us, eu regions for DoubleDouble service
+	regions          []string
-	lastAPICallTime  time.Time // Rate limiting: track last API call
+	lastAPICallTime  time.Time
-	apiCallCount     int       // Rate limiting: counter per minute
+	apiCallCount     int
-	apiCallResetTime time.Time // Rate limiting: reset time
+	apiCallResetTime time.Time
 }
 
 var (
-	// Global Amazon downloader instance for connection reuse
 	globalAmazonDownloader *AmazonDownloader
 	amazonDownloaderOnce   sync.Once
-	amazonRateLimitMu      sync.Mutex // Mutex for rate limiting
+	amazonRateLimitMu      sync.Mutex
 )
 
 // DoubleDoubleSubmitResponse is the response from DoubleDouble submit endpoint
@@ -37,7 +37,6 @@ type DoubleDoubleSubmitResponse struct {
 	ID      string `json:"id"`
 }
 
-// DoubleDoubleStatusResponse is the response from DoubleDouble status endpoint
 type DoubleDoubleStatusResponse struct {
 	Status         string `json:"status"`
 	FriendlyStatus string `json:"friendlyStatus"`
@@ -48,22 +47,18 @@ type DoubleDoubleStatusResponse struct {
 	} `json:"current"`
 }
 
-// amazonArtistsMatch checks if the artist names are similar enough
 func amazonArtistsMatch(expectedArtist, foundArtist string) bool {
 	normExpected := strings.ToLower(strings.TrimSpace(expectedArtist))
 	normFound := strings.ToLower(strings.TrimSpace(foundArtist))
 
-	// Exact match
 	if normExpected == normFound {
 		return true
 	}
 
-	// Check if one contains the other
 	if strings.Contains(normExpected, normFound) || strings.Contains(normFound, normExpected) {
 		return true
 	}
 
-	// Check first artist (before comma or feat)
 	expectedFirst := strings.Split(normExpected, ",")[0]
 	expectedFirst = strings.Split(expectedFirst, " feat")[0]
 	expectedFirst = strings.Split(expectedFirst, " ft.")[0]
@@ -78,24 +73,20 @@ func amazonArtistsMatch(expectedArtist, foundArtist string) bool {
 		return true
 	}
 
-	// Check if first artist is contained in the other
 	if strings.Contains(expectedFirst, foundFirst) || strings.Contains(foundFirst, expectedFirst) {
 		return true
 	}
 
-	// If scripts are different (one is ASCII, one is non-ASCII like Japanese/Chinese/Korean),
-	// assume they're the same artist with different transliteration
 	expectedASCII := amazonIsASCIIString(expectedArtist)
 	foundASCII := amazonIsASCIIString(foundArtist)
 	if expectedASCII != foundASCII {
-		fmt.Printf("[Amazon] Artist names in different scripts, assuming match: '%s' vs '%s'\n", expectedArtist, foundArtist)
+		GoLog("[Amazon] Artist names in different scripts, assuming match: '%s' vs '%s'\n", expectedArtist, foundArtist)
 		return true
 	}
 
 	return false
 }
 
-// amazonIsASCIIString checks if a string contains only ASCII characters
 func amazonIsASCIIString(s string) bool {
 	for _, r := range s {
 		if r > 127 {
@@ -105,7 +96,6 @@ func amazonIsASCIIString(s string) bool {
 	return true
 }
 
-// NewAmazonDownloader creates a new Amazon downloader (returns singleton for connection reuse)
 func NewAmazonDownloader() *AmazonDownloader {
 	amazonDownloaderOnce.Do(func() {
 		globalAmazonDownloader = &AmazonDownloader{
@@ -118,47 +108,41 @@ func NewAmazonDownloader() *AmazonDownloader {
 }
 
 // waitForRateLimit implements rate limiting similar to PC version
-// Max 9 requests per minute with 7 second delay between requests
 func (a *AmazonDownloader) waitForRateLimit() {
 	amazonRateLimitMu.Lock()
 	defer amazonRateLimitMu.Unlock()
 
 	now := time.Now()
 
-	// Reset counter every minute
 	if now.Sub(a.apiCallResetTime) >= time.Minute {
 		a.apiCallCount = 0
 		a.apiCallResetTime = now
 	}
 
-	// If we've hit the limit (9 requests per minute), wait until next minute
 	if a.apiCallCount >= 9 {
 		waitTime := time.Minute - now.Sub(a.apiCallResetTime)
 		if waitTime > 0 {
-			fmt.Printf("[Amazon] Rate limit reached, waiting %v...\n", waitTime.Round(time.Second))
+			GoLog("[Amazon] Rate limit reached, waiting %v...\n", waitTime.Round(time.Second))
 			time.Sleep(waitTime)
 			a.apiCallCount = 0
 			a.apiCallResetTime = time.Now()
 		}
 	}
 
-	// Add delay between requests (7 seconds like PC version)
 	if !a.lastAPICallTime.IsZero() {
 		timeSinceLastCall := now.Sub(a.lastAPICallTime)
 		minDelay := 7 * time.Second
 		if timeSinceLastCall < minDelay {
 			waitTime := minDelay - timeSinceLastCall
-			fmt.Printf("[Amazon] Rate limiting: waiting %v...\n", waitTime.Round(time.Second))
+			GoLog("[Amazon] Rate limiting: waiting %v...\n", waitTime.Round(time.Second))
 			time.Sleep(waitTime)
 		}
 	}
 
-	// Update tracking
 	a.lastAPICallTime = time.Now()
 	a.apiCallCount++
 }
 
-// GetAvailableAPIs returns list of available DoubleDouble regions
 // Uses same service as PC version (doubledouble.top)
 func (a *AmazonDownloader) GetAvailableAPIs() []string {
 	// DoubleDouble service regions (same as PC)
@@ -173,23 +157,19 @@ func (a *AmazonDownloader) GetAvailableAPIs() []string {
 // downloadFromDoubleDoubleService downloads a track using DoubleDouble service (same as PC)
 // This uses submit → poll → download mechanism
 // Internal function - not exported to gomobile
-func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir string) (string, string, string, error) {
+func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, _ string) (string, string, string, error) {
 	var lastError error
 
 	for _, region := range a.regions {
-		fmt.Printf("[Amazon] Trying region: %s...\n", region)
+		GoLog("[Amazon] Trying region: %s...\n", region)
 
-		// Build base URL for DoubleDouble service
-		// Decode base64 service URL (same as PC)
 		serviceBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly8=")               // https://
 		serviceDomain, _ := base64.StdEncoding.DecodeString("LmRvdWJsZWRvdWJsZS50b3A=") // .doubledouble.top
 		baseURL := fmt.Sprintf("%s%s%s", string(serviceBase), region, string(serviceDomain))
 
-		// Step 1: Submit download request with rate limiting
 		encodedURL := url.QueryEscape(amazonURL)
 		submitURL := fmt.Sprintf("%s/dl?url=%s", baseURL, encodedURL)
 
-		// Apply rate limiting before request (like PC version)
 		a.waitForRateLimit()
 
 		req, err := http.NewRequest("GET", submitURL, nil)
@@ -216,7 +196,7 @@ func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir
 				resp.Body.Close()
 				if retry < maxRetries-1 {
 					waitTime := 15 * time.Second
-					fmt.Printf("[Amazon] Rate limited (429), waiting %v before retry %d/%d...\n", waitTime, retry+2, maxRetries)
+					GoLog("[Amazon] Rate limited (429), waiting %v before retry %d/%d...\n", waitTime, retry+2, maxRetries)
 					time.Sleep(waitTime)
 					continue
 				}
@@ -255,7 +235,7 @@ func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir
 		}
 
 		downloadID := submitResp.ID
-		fmt.Printf("[Amazon] Download ID: %s\n", downloadID)
+		GoLog("[Amazon] Download ID: %s\n", downloadID)
 
 		// Step 2: Poll for completion
 		statusURL := fmt.Sprintf("%s/dl/%s", baseURL, downloadID)
@@ -299,7 +279,6 @@ func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir
 			if status.Status == "done" {
 				fmt.Println("\n[Amazon] Download ready!")
 
-				// Build download URL
 				fileURL := status.URL
 				if strings.HasPrefix(fileURL, "./") {
 					fileURL = fmt.Sprintf("%s/%s", baseURL, fileURL[2:])
@@ -310,7 +289,7 @@ func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir
 				trackName := status.Current.Name
 				artist := status.Current.Artist
 
-				fmt.Printf("[Amazon] Downloading: %s - %s\n", artist, trackName)
+				GoLog("[Amazon] Downloading: %s - %s\n", artist, trackName)
 				return fileURL, trackName, artist, nil
 
 			} else if status.Status == "error" {
@@ -344,15 +323,22 @@ func (a *AmazonDownloader) downloadFromDoubleDoubleService(amazonURL, outputDir
 	return "", "", "", fmt.Errorf("all regions failed. Last error: %v", lastError)
 }
 
-// DownloadFile downloads a file from URL with User-Agent and progress tracking
 func (a *AmazonDownloader) DownloadFile(downloadURL, outputPath, itemID string) error {
+	ctx := context.Background()
+
 	// Initialize item progress (required for all downloads)
 	if itemID != "" {
 		StartItemProgress(itemID)
 		defer CompleteItemProgress(itemID)
+		ctx = initDownloadCancel(itemID)
+		defer clearDownloadCancel(itemID)
 	}
 
-	req, err := http.NewRequest("GET", downloadURL, nil)
+	if isDownloadCancelled(itemID) {
+		return ErrDownloadCancelled
+	}
+
+	req, err := http.NewRequestWithContext(ctx, "GET", downloadURL, nil)
 	if err != nil {
 		return fmt.Errorf("failed to create request: %w", err)
 	}
@@ -361,6 +347,9 @@ func (a *AmazonDownloader) DownloadFile(downloadURL, outputPath, itemID string)
 
 	resp, err := a.client.Do(req)
 	if err != nil {
+		if isDownloadCancelled(itemID) {
+			return ErrDownloadCancelled
+		}
 		return err
 	}
 	defer resp.Body.Close()
@@ -370,7 +359,6 @@ func (a *AmazonDownloader) DownloadFile(downloadURL, outputPath, itemID string)
 	}
 
 	expectedSize := resp.ContentLength
-	// Set total bytes if available
 	if expectedSize > 0 && itemID != "" {
 		SetItemBytesTotal(itemID, expectedSize)
 	}
@@ -380,16 +368,13 @@ func (a *AmazonDownloader) DownloadFile(downloadURL, outputPath, itemID string)
 		return err
 	}
 
-	// Use buffered writer for better performance (256KB buffer)
 	bufWriter := bufio.NewWriterSize(out, 256*1024)
 
-	// Use item progress writer with buffered output
 	var written int64
 	if itemID != "" {
 		pw := NewItemProgressWriter(bufWriter, itemID)
 		written, err = io.Copy(pw, resp.Body)
 	} else {
-		// Fallback: direct copy without progress tracking
 		written, err = io.Copy(bufWriter, resp.Body)
 	}
 
@@ -397,9 +382,11 @@ func (a *AmazonDownloader) DownloadFile(downloadURL, outputPath, itemID string)
 	flushErr := bufWriter.Flush()
 	closeErr := out.Close()
 
-	// Check for any errors
 	if err != nil {
 		os.Remove(outputPath)
+		if isDownloadCancelled(itemID) {
+			return ErrDownloadCancelled
+		}
 		return fmt.Errorf("download interrupted: %w", err)
 	}
 	if flushErr != nil {
@@ -435,29 +422,23 @@ type AmazonDownloadResult struct {
 	ISRC        string
 }
 
-// downloadFromAmazon downloads a track using the request parameters
 // Uses DoubleDouble service (same as PC version)
 func downloadFromAmazon(req DownloadRequest) (AmazonDownloadResult, error) {
 	downloader := NewAmazonDownloader()
 
-	// Check for existing file first
 	if existingFile, exists := checkISRCExistsInternal(req.OutputDir, req.ISRC); exists {
 		return AmazonDownloadResult{FilePath: "EXISTS:" + existingFile}, nil
 	}
 
-	// Get Amazon URL from SongLink
 	songlink := NewSongLinkClient()
 	var availability *TrackAvailability
 	var err error
 
-	// Check if SpotifyID is actually a Deezer ID (format: "deezer:xxxxx")
 	if strings.HasPrefix(req.SpotifyID, "deezer:") {
-		// Extract Deezer ID and use Deezer-based lookup
 		deezerID := strings.TrimPrefix(req.SpotifyID, "deezer:")
-		fmt.Printf("[Amazon] Using Deezer ID for SongLink lookup: %s\n", deezerID)
+		GoLog("[Amazon] Using Deezer ID for SongLink lookup: %s\n", deezerID)
 		availability, err = songlink.CheckAvailabilityFromDeezer(deezerID)
 	} else if req.SpotifyID != "" {
-		// Use Spotify ID
 		availability, err = songlink.CheckTrackAvailability(req.SpotifyID, req.ISRC)
 	} else {
 		return AmazonDownloadResult{}, fmt.Errorf("no valid Spotify or Deezer ID provided for Amazon lookup")
@@ -471,7 +452,6 @@ func downloadFromAmazon(req DownloadRequest) (AmazonDownloadResult, error) {
 		return AmazonDownloadResult{}, fmt.Errorf("track not available on Amazon Music (SongLink returned no Amazon URL)")
 	}
 
-	// Create output directory if needed
 	if req.OutputDir != "." {
 		if err := os.MkdirAll(req.OutputDir, 0755); err != nil {
 			return AmazonDownloadResult{}, fmt.Errorf("failed to create output directory: %w", err)
@@ -486,14 +466,12 @@ func downloadFromAmazon(req DownloadRequest) (AmazonDownloadResult, error) {
 
 	// Verify artist matches
 	if artistName != "" && !amazonArtistsMatch(req.ArtistName, artistName) {
-		fmt.Printf("[Amazon] Artist mismatch: expected '%s', got '%s'. Rejecting.\n", req.ArtistName, artistName)
+		GoLog("[Amazon] Artist mismatch: expected '%s', got '%s'. Rejecting.\n", req.ArtistName, artistName)
 		return AmazonDownloadResult{}, fmt.Errorf("artist mismatch: expected '%s', got '%s'", req.ArtistName, artistName)
 	}
 
-	// Log match found
+	GoLog("[Amazon] Match found: '%s' by '%s'\n", trackName, artistName)
-	fmt.Printf("[Amazon] Match found: '%s' by '%s'\n", trackName, artistName)
 
-	// Build filename using Spotify metadata (more accurate)
 	filename := buildFilenameFromTemplate(req.FilenameFormat, map[string]interface{}{
 		"title":  req.TrackName,
 		"artist": req.ArtistName,
@@ -505,7 +483,6 @@ func downloadFromAmazon(req DownloadRequest) (AmazonDownloadResult, error) {
 	filename = sanitizeFilename(filename) + ".flac"
 	outputPath := filepath.Join(req.OutputDir, filename)
 
-	// Check if file already exists
 	if fileInfo, statErr := os.Stat(outputPath); statErr == nil && fileInfo.Size() > 0 {
 		return AmazonDownloadResult{FilePath: "EXISTS:" + outputPath}, nil
 	}
@@ -522,19 +499,21 @@ func downloadFromAmazon(req DownloadRequest) (AmazonDownloadResult, error) {
 			req.TrackName,
 			req.ArtistName,
 			req.EmbedLyrics,
+			int64(req.DurationMS),
 		)
 	}()
 
 	// Download audio file with item ID for progress tracking
 	if err := downloader.DownloadFile(downloadURL, outputPath, req.ItemID); err != nil {
+		if errors.Is(err, ErrDownloadCancelled) {
+			return AmazonDownloadResult{}, ErrDownloadCancelled
+		}
 		return AmazonDownloadResult{}, fmt.Errorf("download failed: %w", err)
 	}
 
 	// Wait for parallel operations to complete
 	<-parallelDone
 
-	// Set progress to 100% and status to finalizing (before embedding)
-	// This makes the UI show "Finalizing..." while embedding happens
 	if req.ItemID != "" {
 		SetItemProgress(req.ItemID, 1.0, 0, 0)
 		SetItemFinalizing(req.ItemID)
@@ -542,24 +521,21 @@ func downloadFromAmazon(req DownloadRequest) (AmazonDownloadResult, error) {
 
 	// Log track info from DoubleDouble (for debugging)
 	if trackName != "" && artistName != "" {
-		fmt.Printf("[Amazon] DoubleDouble returned: %s - %s\n", artistName, trackName)
+		GoLog("[Amazon] DoubleDouble returned: %s - %s\n", artistName, trackName)
 	}
 
-	// Read existing metadata from downloaded file BEFORE embedding
-	// Amazon/DoubleDouble files often have correct track/disc numbers that we should preserve
 	existingMeta, metaErr := ReadMetadata(outputPath)
 	actualTrackNum := req.TrackNumber
 	actualDiscNum := req.DiscNumber
 
 	if metaErr == nil && existingMeta != nil {
-		// Use file metadata if it has valid track/disc numbers and request doesn't have them
 		if existingMeta.TrackNumber > 0 && (req.TrackNumber == 0 || req.TrackNumber == 1) {
 			actualTrackNum = existingMeta.TrackNumber
-			fmt.Printf("[Amazon] Using track number from file: %d (request had: %d)\n", actualTrackNum, req.TrackNumber)
+			GoLog("[Amazon] Using track number from file: %d (request had: %d)\n", actualTrackNum, req.TrackNumber)
 		}
 		if existingMeta.DiscNumber > 0 && (req.DiscNumber == 0 || req.DiscNumber == 1) {
 			actualDiscNum = existingMeta.DiscNumber
-			fmt.Printf("[Amazon] Using disc number from file: %d (request had: %d)\n", actualDiscNum, req.DiscNumber)
+			GoLog("[Amazon] Using disc number from file: %d (request had: %d)\n", actualDiscNum, req.DiscNumber)
 		}
 	}
 
@@ -575,26 +551,44 @@ func downloadFromAmazon(req DownloadRequest) (AmazonDownloadResult, error) {
 		TotalTracks: req.TotalTracks,
 		DiscNumber:  actualDiscNum,
 		ISRC:        req.ISRC,
+		Genre:       req.Genre,     // From Deezer album metadata
+		Label:       req.Label,     // From Deezer album metadata
+		Copyright:   req.Copyright, // From Deezer album metadata
 	}
 
 	// Use cover data from parallel fetch
 	var coverData []byte
 	if parallelResult != nil && parallelResult.CoverData != nil {
 		coverData = parallelResult.CoverData
-		fmt.Printf("[Amazon] Using parallel-fetched cover (%d bytes)\n", len(coverData))
+		GoLog("[Amazon] Using parallel-fetched cover (%d bytes)\n", len(coverData))
 	}
 
 	if err := EmbedMetadataWithCoverData(outputPath, metadata, coverData); err != nil {
 		fmt.Printf("Warning: failed to embed metadata: %v\n", err)
 	}
 
-	// Embed lyrics from parallel fetch
 	if req.EmbedLyrics && parallelResult != nil && parallelResult.LyricsLRC != "" {
-		fmt.Printf("[Amazon] Embedding parallel-fetched lyrics (%d lines)...\n", len(parallelResult.LyricsData.Lines))
+		lyricsMode := req.LyricsMode
-		if embedErr := EmbedLyrics(outputPath, parallelResult.LyricsLRC); embedErr != nil {
+		if lyricsMode == "" {
-			fmt.Printf("[Amazon] Warning: failed to embed lyrics: %v\n", embedErr)
+			lyricsMode = "embed" // default
-		} else {
+		}
-			fmt.Println("[Amazon] Lyrics embedded successfully")
+
+		if lyricsMode == "external" || lyricsMode == "both" {
+			GoLog("[Amazon] Saving external LRC file...\n")
+			if lrcPath, lrcErr := SaveLRCFile(outputPath, parallelResult.LyricsLRC); lrcErr != nil {
+				GoLog("[Amazon] Warning: failed to save LRC file: %v\n", lrcErr)
+			} else {
+				GoLog("[Amazon] LRC file saved: %s\n", lrcPath)
+			}
+		}
+
+		if lyricsMode == "embed" || lyricsMode == "both" {
+			GoLog("[Amazon] Embedding parallel-fetched lyrics (%d lines)...\n", len(parallelResult.LyricsData.Lines))
+			if embedErr := EmbedLyrics(outputPath, parallelResult.LyricsLRC); embedErr != nil {
+				GoLog("[Amazon] Warning: failed to embed lyrics: %v\n", embedErr)
+			} else {
+				fmt.Println("[Amazon] Lyrics embedded successfully")
+			}
 		}
 	} else if req.EmbedLyrics {
 		fmt.Println("[Amazon] No lyrics available from parallel fetch")
@@ -602,25 +596,20 @@ func downloadFromAmazon(req DownloadRequest) (AmazonDownloadResult, error) {
 
 	fmt.Println("[Amazon] ✓ Downloaded successfully from Amazon Music")
 
-	// Read actual quality from the downloaded FLAC file
-	// Amazon API doesn't provide quality info, but we can read it from the file itself
 	quality, err := GetAudioQuality(outputPath)
 	if err != nil {
-		fmt.Printf("[Amazon] Warning: couldn't read quality from file: %v\n", err)
+		GoLog("[Amazon] Warning: couldn't read quality from file: %v\n", err)
 	} else {
-		fmt.Printf("[Amazon] Actual quality: %d-bit/%dHz\n", quality.BitDepth, quality.SampleRate)
+		GoLog("[Amazon] Actual quality: %d-bit/%dHz\n", quality.BitDepth, quality.SampleRate)
 	}
 
-	// Read metadata from file AFTER embedding to get accurate values
-	// This ensures we return what's actually in the file
 	finalMeta, metaReadErr := ReadMetadata(outputPath)
 	if metaReadErr == nil && finalMeta != nil {
-		fmt.Printf("[Amazon] Final metadata from file - Track: %d, Disc: %d, Date: %s\n",
+		GoLog("[Amazon] Final metadata from file - Track: %d, Disc: %d, Date: %s\n",
 			finalMeta.TrackNumber, finalMeta.DiscNumber, finalMeta.Date)
 		actualTrackNum = finalMeta.TrackNumber
 		actualDiscNum = finalMeta.DiscNumber
 		if finalMeta.Date != "" {
-			// Use date from file if available
 			req.ReleaseDate = finalMeta.Date
 		}
 	}

go_backend/cancel.go

@@ -0,0 +1,78 @@
+package gobackend
+
+import (
+	"context"
+	"errors"
+	"sync"
+)
+
+// ErrDownloadCancelled is returned when a download is cancelled by the user.
+var ErrDownloadCancelled = errors.New("download cancelled")
+
+type cancelEntry struct {
+	cancel   context.CancelFunc
+	canceled bool
+}
+
+var (
+	cancelMu  sync.Mutex
+	cancelMap = make(map[string]*cancelEntry)
+)
+
+func initDownloadCancel(itemID string) context.Context {
+	if itemID == "" {
+		return context.Background()
+	}
+
+	cancelMu.Lock()
+	defer cancelMu.Unlock()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancelMap[itemID] = &cancelEntry{
+		cancel:   cancel,
+		canceled: false,
+	}
+	return ctx
+}
+
+func cancelDownload(itemID string) {
+	if itemID == "" {
+		return
+	}
+
+	cancelMu.Lock()
+	entry, ok := cancelMap[itemID]
+	if ok {
+		entry.canceled = true
+		if entry.cancel != nil {
+			entry.cancel()
+		}
+	} else {
+		cancelMap[itemID] = &cancelEntry{canceled: true}
+	}
+	cancelMu.Unlock()
+
+	RemoveItemProgress(itemID)
+}
+
+func isDownloadCancelled(itemID string) bool {
+	if itemID == "" {
+		return false
+	}
+
+	cancelMu.Lock()
+	entry, ok := cancelMap[itemID]
+	canceled := ok && entry.canceled
+	cancelMu.Unlock()
+	return canceled
+}
+
+func clearDownloadCancel(itemID string) {
+	if itemID == "" {
+		return
+	}
+
+	cancelMu.Lock()
+	delete(cancelMap, itemID)
+	cancelMu.Unlock()
+}

go_backend/cover.go

@@ -4,36 +4,53 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"regexp"
 	"strings"
 )
 
-// Spotify image size codes (same as PC version)
 const (
-	spotifySize640 = "ab67616d0000b273" // 640x640
+	spotifySize300 = "ab67616d00001e02"
-	spotifySizeMax = "ab67616d000082c1" // Max resolution (~2000x2000)
+	spotifySize640 = "ab67616d0000b273"
+	spotifySizeMax = "ab67616d000082c1"
 )
 
-// downloadCoverToMemory downloads cover art and returns as bytes (no file creation)
+// Deezer CDN supports these sizes: 56, 250, 500, 1000, 1400, 1800
-// This avoids file permission issues on Android
+var deezerSizeRegex = regexp.MustCompile(`/(\d+)x(\d+)-\d+-\d+-\d+-\d+\.jpg$`)
+
+func convertSmallToMedium(imageURL string) string {
+	if strings.Contains(imageURL, spotifySize300) {
+		return strings.Replace(imageURL, spotifySize300, spotifySize640, 1)
+	}
+	return imageURL
+}
+
 func downloadCoverToMemory(coverURL string, maxQuality bool) ([]byte, error) {
 	if coverURL == "" {
 		return nil, fmt.Errorf("no cover URL provided")
 	}
 
-	fmt.Printf("[Cover] Downloading cover from: %s\n", coverURL)
+	GoLog("[Cover] Original URL: %s", coverURL)
+
+	downloadURL := convertSmallToMedium(coverURL)
+	if downloadURL != coverURL {
+		GoLog("[Cover] Upgraded 300x300 → 640x640")
+	}
 
-	// Upgrade to max quality if requested
-	downloadURL := coverURL
 	if maxQuality {
-		downloadURL = upgradeToMaxQuality(coverURL)
+		maxURL := upgradeToMaxQuality(downloadURL)
-		if downloadURL != coverURL {
+		if maxURL != downloadURL {
-			fmt.Printf("[Cover] Upgraded to max quality URL: %s\n", downloadURL)
+			downloadURL = maxURL
+			// Log already printed by upgradeToMaxQuality for Deezer
+			if strings.Contains(coverURL, "scdn.co") || strings.Contains(coverURL, "spotifycdn") {
+				GoLog("[Cover] Spotify: upgraded to max resolution (~2000x2000)")
+			}
 		}
 	}
 
+	GoLog("[Cover] Final URL: %s", downloadURL)
+
 	client := NewHTTPClientWithTimeout(DefaultTimeout)
 
-	// Create request with User-Agent (required by Spotify CDN)
 	req, err := http.NewRequest("GET", downloadURL, nil)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create request: %w", err)
@@ -54,48 +71,58 @@ func downloadCoverToMemory(coverURL string, maxQuality bool) ([]byte, error) {
 		return nil, fmt.Errorf("failed to read cover data: %w", err)
 	}
 
-	fmt.Printf("[Cover] Downloaded %d bytes\n", len(data))
+	sizeKB := len(data) / 1024
+	var resolution string
+	if sizeKB > 200 {
+		resolution = "~2000x2000 (hi-res)"
+	} else if sizeKB > 50 {
+		resolution = "~640x640"
+	} else {
+		resolution = "~300x300"
+	}
+	GoLog("[Cover] Downloaded %d KB (%s)", sizeKB, resolution)
+
 	return data, nil
 }
 
-// upgradeToMaxQuality upgrades Spotify cover URL to maximum quality
-// Uses same logic as PC version - replaces 640x640 size code with max resolution
 func upgradeToMaxQuality(coverURL string) string {
-	// Spotify image URLs can be upgraded by changing the size parameter
+	// Spotify CDN upgrade
-	// Format: https://i.scdn.co/image/ab67616d0000b273...
-	// ab67616d0000b273 = 640x640
-	// ab67616d000082c1 = Max resolution (~2000x2000)
-
 	if strings.Contains(coverURL, spotifySize640) {
-		// Try max resolution first
+		return strings.Replace(coverURL, spotifySize640, spotifySizeMax, 1)
-		maxURL := strings.Replace(coverURL, spotifySize640, spotifySizeMax, 1)
+	}
 
-		// Verify max resolution URL is available
+	// Deezer CDN upgrade
-		client := NewHTTPClientWithTimeout(DefaultTimeout)
+	if strings.Contains(coverURL, "cdn-images.dzcdn.net") {
-		req, err := http.NewRequest("HEAD", maxURL, nil)
+		return upgradeDeezerCover(coverURL)
-		if err == nil {
-			resp, err := DoRequestWithUserAgent(client, req)
-			if err == nil {
-				resp.Body.Close()
-				if resp.StatusCode == http.StatusOK {
-					return maxURL
-				}
-			}
-		}
 	}
 
 	return coverURL
 }
 
-// GetCoverFromSpotify gets cover URL from Spotify metadata
+func upgradeDeezerCover(coverURL string) string {
+	if !strings.Contains(coverURL, "cdn-images.dzcdn.net") {
+		return coverURL
+	}
+
+	// Replace any size pattern with 1800x1800
+	upgraded := deezerSizeRegex.ReplaceAllString(coverURL, "/1800x1800-000000-80-0-0.jpg")
+	if upgraded != coverURL {
+		GoLog("[Cover] Deezer: upgraded to 1800x1800")
+	}
+	return upgraded
+}
+
 func GetCoverFromSpotify(imageURL string, maxQuality bool) string {
 	if imageURL == "" {
 		return ""
 	}
 
+	// Always upgrade small to medium first
+	result := convertSmallToMedium(imageURL)
+
 	if maxQuality {
-		return upgradeToMaxQuality(imageURL)
+		result = upgradeToMaxQuality(result)
 	}
 
-	return imageURL
+	return result
 }

go_backend/deezer.go

@@ -19,30 +19,26 @@ const (
 	deezerAlbumURL    = deezerBaseURL + "/album/%s"
 	deezerArtistURL   = deezerBaseURL + "/artist/%s"
 	deezerPlaylistURL = deezerBaseURL + "/playlist/%s"
-	
+
 	deezerCacheTTL = 10 * time.Minute
-	
+
-	// Parallel ISRC fetching settings
+	deezerMaxParallelISRC = 10
-	deezerMaxParallelISRC = 10 // Max concurrent ISRC fetches
 )
 
-// DeezerClient handles Deezer API interactions (no auth required)
 type DeezerClient struct {
 	httpClient  *http.Client
 	searchCache map[string]*cacheEntry
 	albumCache  map[string]*cacheEntry
 	artistCache map[string]*cacheEntry
-	isrcCache   map[string]string // trackID -> ISRC cache
+	isrcCache   map[string]string
 	cacheMu     sync.RWMutex
 }
 
-// Singleton instance
 var (
 	deezerClient     *DeezerClient
 	deezerClientOnce sync.Once
 )
 
-// GetDeezerClient returns singleton Deezer client
 func GetDeezerClient() *DeezerClient {
 	deezerClientOnce.Do(func() {
 		deezerClient = &DeezerClient{
@@ -56,29 +52,28 @@ func GetDeezerClient() *DeezerClient {
 	return deezerClient
 }
 
-// Deezer API response types
 type deezerTrack struct {
-	ID             int64  `json:"id"`
+	ID            int64             `json:"id"`
-	Title          string `json:"title"`
+	Title         string            `json:"title"`
-	Duration       int    `json:"duration"` // in seconds
+	Duration      int               `json:"duration"` // in seconds
-	TrackPosition  int    `json:"track_position"`
+	TrackPosition int               `json:"track_position"`
-	DiskNumber     int    `json:"disk_number"`
+	DiskNumber    int               `json:"disk_number"`
-	ISRC           string `json:"isrc"`
+	ISRC          string            `json:"isrc"`
-	Link           string `json:"link"`
+	Link          string            `json:"link"`
-	ReleaseDate    string `json:"release_date"` // Sometimes at track level
+	ReleaseDate   string            `json:"release_date"`
-	Artist         deezerArtist `json:"artist"`
+	Artist        deezerArtist      `json:"artist"`
-	Album          deezerAlbumSimple `json:"album"`
+	Album         deezerAlbumSimple `json:"album"`
-	Contributors   []deezerArtist `json:"contributors"`
+	Contributors  []deezerArtist    `json:"contributors"`
 }
 
 type deezerArtist struct {
-	ID        int64  `json:"id"`
+	ID            int64  `json:"id"`
-	Name      string `json:"name"`
+	Name          string `json:"name"`
-	Picture   string `json:"picture"`
+	Picture       string `json:"picture"`
 	PictureMedium string `json:"picture_medium"`
 	PictureBig    string `json:"picture_big"`
 	PictureXL     string `json:"picture_xl"`
-	NbFan     int    `json:"nb_fan"`
+	NbFan         int    `json:"nb_fan"`
 }
 
 type deezerAlbumSimple struct {
@@ -88,11 +83,10 @@ type deezerAlbumSimple struct {
 	CoverMedium string `json:"cover_medium"`
 	CoverBig    string `json:"cover_big"`
 	CoverXL     string `json:"cover_xl"`
-	ReleaseDate string `json:"release_date"` // Sometimes at album level
+	ReleaseDate string `json:"release_date"`
+	RecordType  string `json:"record_type"`
 }
-// ... (skip other structs as they are fine/unchanged) ...
 
-// ... (in convertTrack) ...
 func (c *DeezerClient) convertTrack(track deezerTrack) TrackMetadata {
 	artistName := track.Artist.Name
 	if len(track.Contributors) > 0 {
@@ -113,8 +107,7 @@ func (c *DeezerClient) convertTrack(track deezerTrack) TrackMetadata {
 	if albumImage == "" {
 		albumImage = track.Album.Cover
 	}
-	
+
-	// Try to find release date
 	releaseDate := track.ReleaseDate
 	if releaseDate == "" {
 		releaseDate = track.Album.ReleaseDate
@@ -136,6 +129,11 @@ func (c *DeezerClient) convertTrack(track deezerTrack) TrackMetadata {
 	}
 }
 
+type deezerGenre struct {
+	ID   int    `json:"id"`
+	Name string `json:"name"`
+}
+
 type deezerAlbumFull struct {
 	ID          int64  `json:"id"`
 	Title       string `json:"title"`
@@ -145,9 +143,14 @@ type deezerAlbumFull struct {
 	CoverXL     string `json:"cover_xl"`
 	ReleaseDate string `json:"release_date"`
 	NbTracks    int    `json:"nb_tracks"`
-	Artist      deezerArtist `json:"artist"`
+	RecordType  string `json:"record_type"`
+	Label       string `json:"label"`
+	Genres      struct {
+		Data []deezerGenre `json:"data"`
+	} `json:"genres"`
+	Artist       deezerArtist   `json:"artist"`
 	Contributors []deezerArtist `json:"contributors"`
-	Tracks      struct {
+	Tracks       struct {
 		Data []deezerTrack `json:"data"`
 	} `json:"tracks"`
 }
@@ -164,70 +167,100 @@ type deezerArtistFull struct {
 }
 
 type deezerPlaylistFull struct {
-	ID          int64  `json:"id"`
+	ID            int64  `json:"id"`
-	Title       string `json:"title"`
+	Title         string `json:"title"`
-	Picture     string `json:"picture"`
+	Picture       string `json:"picture"`
 	PictureMedium string `json:"picture_medium"`
 	PictureBig    string `json:"picture_big"`
 	PictureXL     string `json:"picture_xl"`
-	NbTracks    int    `json:"nb_tracks"`
+	NbTracks      int    `json:"nb_tracks"`
-	Creator     struct {
+	Creator       struct {
 		Name string `json:"name"`
 	} `json:"creator"`
-	Tracks      struct {
+	Tracks struct {
 		Data []deezerTrack `json:"data"`
 	} `json:"tracks"`
 }
 
-// SearchAll searches for tracks and artists on Deezer
 // NOTE: ISRC is NOT fetched during search for performance - use GetTrackISRC when needed for download
 func (c *DeezerClient) SearchAll(ctx context.Context, query string, trackLimit, artistLimit int) (*SearchAllResult, error) {
+	GoLog("[Deezer] SearchAll: query=%q, trackLimit=%d, artistLimit=%d\n", query, trackLimit, artistLimit)
+
 	cacheKey := fmt.Sprintf("deezer:all:%s:%d:%d", query, trackLimit, artistLimit)
-	
+
 	c.cacheMu.RLock()
 	if entry, ok := c.searchCache[cacheKey]; ok && !entry.isExpired() {
 		c.cacheMu.RUnlock()
+		GoLog("[Deezer] SearchAll: returning cached result\n")
 		return entry.data.(*SearchAllResult), nil
 	}
 	c.cacheMu.RUnlock()
 
 	result := &SearchAllResult{
-		Tracks:  make([]TrackMetadata, 0),
+		Tracks:  make([]TrackMetadata, 0, trackLimit),
-		Artists: make([]SearchArtistResult, 0),
+		Artists: make([]SearchArtistResult, 0, artistLimit),
 	}
 
 	// Search tracks - NO ISRC fetch for performance
 	trackURL := fmt.Sprintf("%s/track?q=%s&limit=%d", deezerSearchURL, url.QueryEscape(query), trackLimit)
+	GoLog("[Deezer] Fetching tracks from: %s\n", trackURL)
+
 	var trackResp struct {
-		Data []deezerTrack `json:"data"`
+		Data  []deezerTrack `json:"data"`
+		Error *struct {
+			Type    string `json:"type"`
+			Message string `json:"message"`
+			Code    int    `json:"code"`
+		} `json:"error"`
 	}
 	if err := c.getJSON(ctx, trackURL, &trackResp); err != nil {
+		GoLog("[Deezer] Track search failed: %v\n", err)
 		return nil, fmt.Errorf("deezer track search failed: %w", err)
 	}
 
+	if trackResp.Error != nil {
+		GoLog("[Deezer] API error: type=%s, code=%d, message=%s\n", trackResp.Error.Type, trackResp.Error.Code, trackResp.Error.Message)
+		return nil, fmt.Errorf("deezer API error: %s (code %d)", trackResp.Error.Message, trackResp.Error.Code)
+	}
+
+	GoLog("[Deezer] Got %d tracks from API\n", len(trackResp.Data))
+
 	for _, track := range trackResp.Data {
-		// Convert directly without fetching ISRC - much faster
 		result.Tracks = append(result.Tracks, c.convertTrack(track))
 	}
 
-	// Search artists
 	artistURL := fmt.Sprintf("%s/artist?q=%s&limit=%d", deezerSearchURL, url.QueryEscape(query), artistLimit)
+	GoLog("[Deezer] Fetching artists from: %s\n", artistURL)
+
 	var artistResp struct {
-		Data []deezerArtist `json:"data"`
+		Data  []deezerArtist `json:"data"`
+		Error *struct {
+			Type    string `json:"type"`
+			Message string `json:"message"`
+			Code    int    `json:"code"`
+		} `json:"error"`
 	}
 	if err := c.getJSON(ctx, artistURL, &artistResp); err == nil {
-		for _, artist := range artistResp.Data {
+		if artistResp.Error != nil {
-			result.Artists = append(result.Artists, SearchArtistResult{
+			GoLog("[Deezer] Artist API error: type=%s, code=%d, message=%s\n", artistResp.Error.Type, artistResp.Error.Code, artistResp.Error.Message)
-				ID:         fmt.Sprintf("deezer:%d", artist.ID),
+		} else {
-				Name:       artist.Name,
+			GoLog("[Deezer] Got %d artists from API\n", len(artistResp.Data))
-				Images:     c.getBestArtistImage(artist),
+			for _, artist := range artistResp.Data {
-				Followers:  artist.NbFan,
+				result.Artists = append(result.Artists, SearchArtistResult{
-				Popularity: 0,
+					ID:         fmt.Sprintf("deezer:%d", artist.ID),
-			})
+					Name:       artist.Name,
+					Images:     c.getBestArtistImage(artist),
+					Followers:  artist.NbFan,
+					Popularity: 0,
+				})
+			}
 		}
+	} else {
+		GoLog("[Deezer] Artist search failed: %v\n", err)
 	}
 
-	// Cache result
+	GoLog("[Deezer] SearchAll complete: %d tracks, %d artists\n", len(result.Tracks), len(result.Artists))
+
 	c.cacheMu.Lock()
 	c.searchCache[cacheKey] = &cacheEntry{
 		data:      result,
@@ -241,7 +274,7 @@ func (c *DeezerClient) SearchAll(ctx context.Context, query string, trackLimit,
 // GetTrack fetches a single track by Deezer ID
 func (c *DeezerClient) GetTrack(ctx context.Context, trackID string) (*TrackResponse, error) {
 	trackURL := fmt.Sprintf(deezerTrackURL, trackID)
-	
+
 	var track deezerTrack
 	if err := c.getJSON(ctx, trackURL, &track); err != nil {
 		return nil, err
@@ -252,7 +285,6 @@ func (c *DeezerClient) GetTrack(ctx context.Context, trackID string) (*TrackResp
 	}, nil
 }
 
-// GetAlbum fetches album with tracks
 // ISRC is fetched in parallel for better performance
 func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResponsePayload, error) {
 	c.cacheMu.RLock()
@@ -263,7 +295,7 @@ func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResp
 	c.cacheMu.RUnlock()
 
 	albumURL := fmt.Sprintf(deezerAlbumURL, albumID)
-	
+
 	var album deezerAlbumFull
 	if err := c.getJSON(ctx, albumURL, &album); err != nil {
 		return nil, err
@@ -279,18 +311,34 @@ func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResp
 		artistName = strings.Join(names, ", ")
 	}
 
+	// Extract genres as comma-separated string
+	var genres []string
+	for _, g := range album.Genres.Data {
+		if g.Name != "" {
+			genres = append(genres, g.Name)
+		}
+	}
+	genreStr := strings.Join(genres, ", ")
+
 	info := AlbumInfoMetadata{
 		TotalTracks: album.NbTracks,
 		Name:        album.Title,
 		ReleaseDate: album.ReleaseDate,
 		Artists:     artistName,
 		Images:      albumImage,
+		Genre:       genreStr,    // From Deezer album
+		Label:       album.Label, // From Deezer album
 	}
 
-	// Fetch ISRCs in parallel
 	isrcMap := c.fetchISRCsParallel(ctx, album.Tracks.Data)
 
 	tracks := make([]AlbumTrackMetadata, 0, len(album.Tracks.Data))
+	// Normalize record_type (Deezer uses "compile" instead of "compilation")
+	albumType := album.RecordType
+	if albumType == "compile" {
+		albumType = "compilation"
+	}
+
 	for _, track := range album.Tracks.Data {
 		trackIDStr := fmt.Sprintf("%d", track.ID)
 		isrc := isrcMap[trackIDStr]
@@ -310,6 +358,7 @@ func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResp
 			ExternalURL: track.Link,
 			ISRC:        isrc,
 			AlbumID:     fmt.Sprintf("deezer:%d", album.ID),
+			AlbumType:   albumType,
 		})
 	}
 
@@ -328,7 +377,6 @@ func (c *DeezerClient) GetAlbum(ctx context.Context, albumID string) (*AlbumResp
 	return result, nil
 }
 
-// GetArtist fetches artist with albums
 func (c *DeezerClient) GetArtist(ctx context.Context, artistID string) (*ArtistResponsePayload, error) {
 	c.cacheMu.RLock()
 	if entry, ok := c.artistCache[artistID]; ok && !entry.isExpired() {
@@ -375,7 +423,7 @@ func (c *DeezerClient) GetArtist(ctx context.Context, artistID string) (*ArtistR
 			if albumType == "compile" {
 				albumType = "compilation"
 			}
-			
+
 			coverURL := album.CoverXL
 			if coverURL == "" {
 				coverURL = album.CoverBig
@@ -414,11 +462,9 @@ func (c *DeezerClient) GetArtist(ctx context.Context, artistID string) (*ArtistR
 	return result, nil
 }
 
-// GetPlaylist fetches playlist with tracks
-// ISRC is fetched in parallel for better performance
 func (c *DeezerClient) GetPlaylist(ctx context.Context, playlistID string) (*PlaylistResponsePayload, error) {
 	playlistURL := fmt.Sprintf(deezerPlaylistURL, playlistID)
-	
+
 	var playlist deezerPlaylistFull
 	if err := c.getJSON(ctx, playlistURL, &playlist); err != nil {
 		return nil, err
@@ -438,7 +484,6 @@ func (c *DeezerClient) GetPlaylist(ctx context.Context, playlistID string) (*Pla
 	info.Owner.Name = playlist.Title
 	info.Owner.Images = playlistImage
 
-	// Fetch ISRCs in parallel
 	isrcMap := c.fetchISRCsParallel(ctx, playlist.Tracks.Data)
 
 	tracks := make([]AlbumTrackMetadata, 0, len(playlist.Tracks.Data))
@@ -477,15 +522,11 @@ func (c *DeezerClient) GetPlaylist(ctx context.Context, playlistID string) (*Pla
 	}, nil
 }
 
-// SearchByISRC searches for a track by ISRC using direct endpoint
 func (c *DeezerClient) SearchByISRC(ctx context.Context, isrc string) (*TrackMetadata, error) {
-	// Use direct ISRC endpoint (API 2.0)
-	// https://api.deezer.com/2.0/track/isrc:{ISRC}
 	directURL := fmt.Sprintf("%s/track/isrc:%s", deezerBaseURL, isrc)
-	
+
 	var track deezerTrack
 	if err := c.getJSON(ctx, directURL, &track); err != nil {
-		// Fallback to search if direct endpoint fails
 		searchURL := fmt.Sprintf("%s/track?q=isrc:%s&limit=1", deezerSearchURL, isrc)
 		var resp struct {
 			Data []deezerTrack `json:"data"`
@@ -500,7 +541,6 @@ func (c *DeezerClient) SearchByISRC(ctx context.Context, isrc string) (*TrackMet
 		return &result, nil
 	}
 
-	// Check if we got a valid response (ID > 0)
 	if track.ID == 0 {
 		return nil, fmt.Errorf("no track found for ISRC: %s", isrc)
 	}
@@ -520,14 +560,24 @@ func (c *DeezerClient) fetchFullTrack(ctx context.Context, trackID string) (*dee
 
 // fetchISRCsParallel fetches ISRCs for multiple tracks in parallel with caching
 func (c *DeezerClient) fetchISRCsParallel(ctx context.Context, tracks []deezerTrack) map[string]string {
-	result := make(map[string]string)
+	result := make(map[string]string, len(tracks))
 	var resultMu sync.Mutex
-	
+
-	// First, check cache for existing ISRCs
 	var tracksToFetch []deezerTrack
+	var directISRCs map[string]string
 	c.cacheMu.RLock()
 	for _, track := range tracks {
 		trackIDStr := fmt.Sprintf("%d", track.ID)
+		if track.ISRC != "" {
+			result[trackIDStr] = track.ISRC
+			if _, ok := c.isrcCache[trackIDStr]; !ok {
+				if directISRCs == nil {
+					directISRCs = make(map[string]string)
+				}
+				directISRCs[trackIDStr] = track.ISRC
+			}
+			continue
+		}
 		if isrc, ok := c.isrcCache[trackIDStr]; ok {
 			result[trackIDStr] = isrc
 		} else {
@@ -535,76 +585,76 @@ func (c *DeezerClient) fetchISRCsParallel(ctx context.Context, tracks []deezerTr
 		}
 	}
 	c.cacheMu.RUnlock()
-	
+	if len(directISRCs) > 0 {
+		c.cacheMu.Lock()
+		for trackIDStr, isrc := range directISRCs {
+			c.isrcCache[trackIDStr] = isrc
+		}
+		c.cacheMu.Unlock()
+	}
+
 	if len(tracksToFetch) == 0 {
 		return result
 	}
-	
+
 	// Use semaphore to limit concurrent requests
 	sem := make(chan struct{}, deezerMaxParallelISRC)
 	var wg sync.WaitGroup
-	
+
 	for _, track := range tracksToFetch {
 		wg.Add(1)
 		go func(t deezerTrack) {
 			defer wg.Done()
-			
+
-			// Acquire semaphore
 			select {
 			case sem <- struct{}{}:
 				defer func() { <-sem }()
 			case <-ctx.Done():
 				return
 			}
-			
+
 			trackIDStr := fmt.Sprintf("%d", t.ID)
 			fullTrack, err := c.fetchFullTrack(ctx, trackIDStr)
 			if err != nil || fullTrack == nil {
 				return
 			}
-			
+
 			// Store in result and cache
 			resultMu.Lock()
 			result[trackIDStr] = fullTrack.ISRC
 			resultMu.Unlock()
-			
+
 			c.cacheMu.Lock()
 			c.isrcCache[trackIDStr] = fullTrack.ISRC
 			c.cacheMu.Unlock()
 		}(track)
 	}
-	
+
 	wg.Wait()
 	return result
 }
 
-// GetTrackISRC fetches ISRC for a single track (with caching)
 // Use this when you need ISRC for download
 func (c *DeezerClient) GetTrackISRC(ctx context.Context, trackID string) (string, error) {
-	// Check cache first
 	c.cacheMu.RLock()
 	if isrc, ok := c.isrcCache[trackID]; ok {
 		c.cacheMu.RUnlock()
 		return isrc, nil
 	}
 	c.cacheMu.RUnlock()
-	
+
-	// Fetch from API
 	fullTrack, err := c.fetchFullTrack(ctx, trackID)
 	if err != nil {
 		return "", err
 	}
-	
+
-	// Cache the result
 	c.cacheMu.Lock()
 	c.isrcCache[trackID] = fullTrack.ISRC
 	c.cacheMu.Unlock()
-	
+
 	return fullTrack.ISRC, nil
 }
 
-
-
 func (c *DeezerClient) getBestArtistImage(artist deezerArtist) string {
 	if artist.PictureXL != "" {
 		return artist.PictureXL
@@ -644,6 +694,104 @@ func (c *DeezerClient) getBestAlbumImage(album deezerAlbumFull) string {
 	return album.Cover
 }
 
+type AlbumExtendedMetadata struct {
+	Genre string // Comma-separated list of genres
+	Label string // Record label name
+}
+
+// Uses the album ID from a track to fetch extended metadata
+func (c *DeezerClient) GetAlbumExtendedMetadata(ctx context.Context, albumID string) (*AlbumExtendedMetadata, error) {
+	if albumID == "" {
+		return nil, fmt.Errorf("empty album ID")
+	}
+
+	cacheKey := fmt.Sprintf("album_meta:%s", albumID)
+	c.cacheMu.RLock()
+	if entry, ok := c.searchCache[cacheKey]; ok && !entry.isExpired() {
+		c.cacheMu.RUnlock()
+		return entry.data.(*AlbumExtendedMetadata), nil
+	}
+	c.cacheMu.RUnlock()
+
+	albumURL := fmt.Sprintf(deezerAlbumURL, albumID)
+
+	var album deezerAlbumFull
+	if err := c.getJSON(ctx, albumURL, &album); err != nil {
+		return nil, fmt.Errorf("failed to fetch album: %w", err)
+	}
+
+	var genres []string
+	for _, g := range album.Genres.Data {
+		if g.Name != "" {
+			genres = append(genres, g.Name)
+		}
+	}
+
+	result := &AlbumExtendedMetadata{
+		Genre: strings.Join(genres, ", "),
+		Label: album.Label,
+	}
+
+	c.cacheMu.Lock()
+	c.searchCache[cacheKey] = &cacheEntry{
+		data:      result,
+		expiresAt: time.Now().Add(deezerCacheTTL),
+	}
+	c.cacheMu.Unlock()
+
+	GoLog("[Deezer] Album metadata fetched - Genre: %s, Label: %s\n", result.Genre, result.Label)
+
+	return result, nil
+}
+
+// GetTrackAlbumID fetches the album ID for a Deezer track
+func (c *DeezerClient) GetTrackAlbumID(ctx context.Context, trackID string) (string, error) {
+	trackURL := fmt.Sprintf(deezerTrackURL, trackID)
+
+	var track deezerTrack
+	if err := c.getJSON(ctx, trackURL, &track); err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("%d", track.Album.ID), nil
+}
+
+// This is a convenience function that first gets the album ID, then fetches album metadata
+func (c *DeezerClient) GetExtendedMetadataByTrackID(ctx context.Context, trackID string) (*AlbumExtendedMetadata, error) {
+	albumID, err := c.GetTrackAlbumID(ctx, trackID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get album ID: %w", err)
+	}
+
+	return c.GetAlbumExtendedMetadata(ctx, albumID)
+}
+
+// GetExtendedMetadataByISRC searches for a track by ISRC and fetches extended metadata (genre, label)
+func (c *DeezerClient) GetExtendedMetadataByISRC(ctx context.Context, isrc string) (*AlbumExtendedMetadata, error) {
+	if isrc == "" {
+		return nil, fmt.Errorf("empty ISRC")
+	}
+
+	// First, search for track by ISRC
+	track, err := c.SearchByISRC(ctx, isrc)
+	if err != nil {
+		return nil, fmt.Errorf("failed to find track by ISRC: %w", err)
+	}
+
+	// SpotifyID contains "deezer:123" format, extract the ID
+	deezerID := track.SpotifyID
+	if strings.HasPrefix(deezerID, "deezer:") {
+		deezerID = strings.TrimPrefix(deezerID, "deezer:")
+	}
+
+	if deezerID == "" {
+		return nil, fmt.Errorf("track found but no Deezer ID")
+	}
+
+	// Then fetch extended metadata using the Deezer track ID
+	return c.GetExtendedMetadataByTrackID(ctx, deezerID)
+}
+
 func (c *DeezerClient) getJSON(ctx context.Context, endpoint string, dst interface{}) error {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
 	if err != nil {
@@ -687,8 +835,7 @@ func parseDeezerURL(input string) (string, string, error) {
 	}
 
 	parts := strings.Split(strings.Trim(parsed.Path, "/"), "/")
-	
+
-	// Skip language prefix if present (e.g., /en/, /fr/)
 	if len(parts) > 0 && len(parts[0]) == 2 {
 		parts = parts[1:]
 	}

go_backend/duplicate.go

@@ -18,30 +18,45 @@ type ISRCIndex struct {
 	mu        sync.RWMutex
 }
 
-// Global ISRC index cache (per output directory)
 var (
 	isrcIndexCache   = make(map[string]*ISRCIndex)
 	isrcIndexCacheMu sync.RWMutex
-	isrcIndexTTL     = 5 * time.Minute // Cache TTL - rebuild after 5 minutes
+	isrcBuildingMu   sync.Map // Per-directory build lock to prevent concurrent builds
+	isrcIndexTTL     = 5 * time.Minute
 )
 
 // GetISRCIndex returns or builds an ISRC index for the given directory
+// Uses per-directory mutex to prevent concurrent builds (race condition fix)
 func GetISRCIndex(outputDir string) *ISRCIndex {
+	// Fast path: check cache first
 	isrcIndexCacheMu.RLock()
 	idx, exists := isrcIndexCache[outputDir]
 	isrcIndexCacheMu.RUnlock()
 
-	// Return cached index if still valid
 	if exists && time.Since(idx.buildTime) < isrcIndexTTL {
 		return idx
 	}
 
-	// Build new index
+	// Slow path: need to build index
+	// Use per-directory mutex to prevent multiple goroutines from building simultaneously
+	buildLock, _ := isrcBuildingMu.LoadOrStore(outputDir, &sync.Mutex{})
+	mu := buildLock.(*sync.Mutex)
+	mu.Lock()
+	defer mu.Unlock()
+
+	// Double-check cache after acquiring lock (another goroutine may have built it)
+	isrcIndexCacheMu.RLock()
+	idx, exists = isrcIndexCache[outputDir]
+	isrcIndexCacheMu.RUnlock()
+
+	if exists && time.Since(idx.buildTime) < isrcIndexTTL {
+		return idx
+	}
+
 	return buildISRCIndex(outputDir)
 }
 
 // buildISRCIndex scans a directory and builds a map of ISRC -> file path
-// Same implementation as PC version for consistency
 func buildISRCIndex(outputDir string) *ISRCIndex {
 	idx := &ISRCIndex{
 		index:     make(map[string]string),
@@ -56,7 +71,6 @@ func buildISRCIndex(outputDir string) *ISRCIndex {
 	startTime := time.Now()
 	fileCount := 0
 
-	// Walk directory - only check .flac files
 	filepath.Walk(outputDir, func(path string, info os.FileInfo, err error) error {
 		if err != nil || info.IsDir() {
 			return nil
@@ -67,13 +81,11 @@ func buildISRCIndex(outputDir string) *ISRCIndex {
 			return nil
 		}
 
-		// Read ISRC from file
 		metadata, err := ReadMetadata(path)
 		if err != nil || metadata.ISRC == "" {
 			return nil
 		}
 
-		// Store in index (uppercase for case-insensitive matching)
 		idx.index[strings.ToUpper(metadata.ISRC)] = path
 		fileCount++
 		return nil
@@ -82,7 +94,6 @@ func buildISRCIndex(outputDir string) *ISRCIndex {
 	fmt.Printf("[ISRCIndex] Built index for %s: %d files in %v\n", 
 		outputDir, fileCount, time.Since(startTime).Round(time.Millisecond))
 
-	// Cache the index
 	isrcIndexCacheMu.Lock()
 	isrcIndexCache[outputDir] = idx
 	isrcIndexCacheMu.Unlock()
@@ -90,7 +101,6 @@ func buildISRCIndex(outputDir string) *ISRCIndex {
 	return idx
 }
 
-// lookup checks if an ISRC exists in the index (internal, returns bool)
 func (idx *ISRCIndex) lookup(isrc string) (string, bool) {
 	if isrc == "" {
 		return "", false
@@ -103,6 +113,18 @@ func (idx *ISRCIndex) lookup(isrc string) (string, bool) {
 	return path, exists
 }
 
+// remove deletes an ISRC entry from the index (internal use)
+func (idx *ISRCIndex) remove(isrc string) {
+	if isrc == "" {
+		return
+	}
+
+	idx.mu.Lock()
+	defer idx.mu.Unlock()
+
+	delete(idx.index, strings.ToUpper(isrc))
+}
+
 // Lookup checks if an ISRC exists in the index (gomobile compatible)
 // Returns filepath if found, empty string if not found
 func (idx *ISRCIndex) Lookup(isrc string) (string, error) {
@@ -136,13 +158,22 @@ func checkISRCExistsInternal(outputDir, isrc string) (string, bool) {
 		return "", false
 	}
 
-	// Use index for fast lookup
 	idx := GetISRCIndex(outputDir)
-	return idx.lookup(isrc)
+	filePath, exists := idx.lookup(isrc)
+	if !exists {
+		return "", false
+	}
+
+	if !CheckFileExists(filePath) {
+		// Stale index entry; remove it and return not found.
+		idx.remove(isrc)
+		return "", false
+	}
+
+	return filePath, true
 }
 
 // CheckISRCExists is the exported version for gomobile (returns string, error)
-// Returns the filepath if exists, empty string if not
 func CheckISRCExists(outputDir, isrc string) (string, error) {
 	filepath, _ := checkISRCExistsInternal(outputDir, isrc)
 	return filepath, nil
@@ -166,11 +197,7 @@ type FileExistenceResult struct {
 	ArtistName string `json:"artist_name,omitempty"`
 }
 
-// CheckFilesExistParallel checks if multiple files exist in parallel
-// It builds an ISRC index from the output directory once, then checks all tracks against it
-// Same implementation as PC version for consistency
 func CheckFilesExistParallel(outputDir string, tracksJSON string) (string, error) {
-	// Parse input JSON
 	var tracks []struct {
 		ISRC       string `json:"isrc"`
 		TrackName  string `json:"track_name"`
@@ -182,10 +209,8 @@ func CheckFilesExistParallel(outputDir string, tracksJSON string) (string, error
 
 	results := make([]FileExistenceResult, len(tracks))
 
-	// Build ISRC index from output directory (scan once)
 	isrcIdx := GetISRCIndex(outputDir)
 
-	// Check each track against the index (parallel)
 	var wg sync.WaitGroup
 	for i, track := range tracks {
 		wg.Add(1)
@@ -216,7 +241,6 @@ func CheckFilesExistParallel(outputDir string, tracksJSON string) (string, error
 
 	wg.Wait()
 
-	// Return results as JSON
 	resultJSON, err := json.Marshal(results)
 	if err != nil {
 		return "", fmt.Errorf("failed to marshal results: %w", err)
@@ -237,7 +261,6 @@ func PreBuildISRCIndex(outputDir string) error {
 }
 
 // AddToISRCIndex adds a new file to the ISRC index after successful download
-// This avoids rebuilding the entire index
 func AddToISRCIndex(outputDir, isrc, filePath string) {
 	if outputDir == "" || isrc == "" || filePath == "" {
 		return

go_backend/extension_manager.go

@@ -0,0 +1,995 @@
+package gobackend
+
+import (
+	"archive/zip"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"sync"
+
+	"github.com/dop251/goja"
+)
+
+func compareVersions(v1, v2 string) int {
+	parts1 := strings.Split(strings.TrimPrefix(v1, "v"), ".")
+	parts2 := strings.Split(strings.TrimPrefix(v2, "v"), ".")
+
+	maxLen := len(parts1)
+	if len(parts2) > maxLen {
+		maxLen = len(parts2)
+	}
+
+	for i := 0; i < maxLen; i++ {
+		var n1, n2 int
+		if i < len(parts1) {
+			n1, _ = strconv.Atoi(parts1[i])
+		}
+		if i < len(parts2) {
+			n2, _ = strconv.Atoi(parts2[i])
+		}
+
+		if n1 < n2 {
+			return -1
+		}
+		if n1 > n2 {
+			return 1
+		}
+	}
+
+	return 0
+}
+
+type LoadedExtension struct {
+	ID        string             `json:"id"`
+	Manifest  *ExtensionManifest `json:"manifest"`
+	VM        *goja.Runtime      `json:"-"`
+	VMMu      sync.Mutex         `json:"-"` // Mutex to prevent concurrent VM access
+	Enabled   bool               `json:"enabled"`
+	Error     string             `json:"error,omitempty"`
+	DataDir   string             `json:"data_dir"`
+	SourceDir string             `json:"source_dir"`
+	IconPath  string             `json:"icon_path"`
+}
+
+// ExtensionManager manages all loaded extensions
+type ExtensionManager struct {
+	mu            sync.RWMutex
+	extensions    map[string]*LoadedExtension
+	extensionsDir string // Base directory for extensions
+	dataDir       string // Base directory for extension data
+}
+
+var (
+	globalExtManager     *ExtensionManager
+	globalExtManagerOnce sync.Once
+)
+
+func GetExtensionManager() *ExtensionManager {
+	globalExtManagerOnce.Do(func() {
+		globalExtManager = &ExtensionManager{
+			extensions: make(map[string]*LoadedExtension),
+		}
+	})
+	return globalExtManager
+}
+
+func (m *ExtensionManager) SetDirectories(extensionsDir, dataDir string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	m.extensionsDir = extensionsDir
+	m.dataDir = dataDir
+
+	if err := os.MkdirAll(extensionsDir, 0755); err != nil {
+		return fmt.Errorf("failed to create extensions directory: %w", err)
+	}
+	if err := os.MkdirAll(dataDir, 0755); err != nil {
+		return fmt.Errorf("failed to create data directory: %w", err)
+	}
+
+	return nil
+}
+
+func (m *ExtensionManager) LoadExtensionFromFile(filePath string) (*LoadedExtension, error) {
+	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
+		return nil, fmt.Errorf("Invalid file format. Please select a .spotiflac-ext file")
+	}
+
+	// Open the zip file
+	zipReader, err := zip.OpenReader(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("Cannot open extension file. The file may be corrupted or not a valid extension package")
+	}
+	defer zipReader.Close()
+
+	var manifestData []byte
+	var hasIndexJS bool
+	for _, file := range zipReader.File {
+		name := filepath.Base(file.Name)
+		if name == "manifest.json" {
+			rc, err := file.Open()
+			if err != nil {
+				return nil, fmt.Errorf("failed to open manifest.json: %w", err)
+			}
+			manifestData, err = io.ReadAll(rc)
+			rc.Close()
+			if err != nil {
+				return nil, fmt.Errorf("failed to read manifest.json: %w", err)
+			}
+		}
+		if name == "index.js" {
+			hasIndexJS = true
+		}
+	}
+
+	if manifestData == nil {
+		return nil, fmt.Errorf("Invalid extension package: manifest.json not found")
+	}
+
+	if !hasIndexJS {
+		return nil, fmt.Errorf("Invalid extension package: index.js not found")
+	}
+
+	manifest, err := ParseManifest(manifestData)
+	if err != nil {
+		return nil, fmt.Errorf("Invalid extension manifest: %w", err)
+	}
+
+	m.mu.RLock()
+	existing, exists := m.extensions[manifest.Name]
+	var existingVersion string
+	var existingDisplayName string
+	if exists {
+		existingVersion = existing.Manifest.Version
+		existingDisplayName = existing.Manifest.DisplayName
+	}
+	m.mu.RUnlock()
+
+	if exists {
+		versionCompare := compareVersions(manifest.Version, existingVersion)
+		if versionCompare > 0 {
+			// This is an upgrade - call UpgradeExtension
+			return m.UpgradeExtension(filePath)
+		} else if versionCompare == 0 {
+			return nil, fmt.Errorf("Extension '%s' v%s is already installed", existingDisplayName, existingVersion)
+		} else {
+			return nil, fmt.Errorf("Cannot downgrade '%s' from v%s to v%s", existingDisplayName, existingVersion, manifest.Version)
+		}
+	}
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if _, exists := m.extensions[manifest.Name]; exists {
+		return nil, fmt.Errorf("Extension '%s' was installed by another process", manifest.DisplayName)
+	}
+
+	extDir := filepath.Join(m.extensionsDir, manifest.Name)
+	if err := os.MkdirAll(extDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create extension directory: %w", err)
+	}
+
+	for _, file := range zipReader.File {
+		if file.FileInfo().IsDir() {
+			continue
+		}
+
+		relPath := filepath.Clean(file.Name)
+		if strings.HasPrefix(relPath, "..") || filepath.IsAbs(relPath) {
+			GoLog("[Extension] Skipping unsafe path in archive: %s\n", file.Name)
+			continue
+		}
+		destPath := filepath.Join(extDir, relPath)
+
+		destDir := filepath.Dir(destPath)
+		if err := os.MkdirAll(destDir, 0755); err != nil {
+			return nil, fmt.Errorf("failed to create directory %s: %w", destDir, err)
+		}
+
+		destFile, err := os.Create(destPath)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create file %s: %w", destPath, err)
+		}
+
+		srcFile, err := file.Open()
+		if err != nil {
+			destFile.Close()
+			return nil, fmt.Errorf("failed to open file in archive: %w", err)
+		}
+
+		_, err = io.Copy(destFile, srcFile)
+		srcFile.Close()
+		destFile.Close()
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract file: %w", err)
+		}
+	}
+
+	extDataDir := filepath.Join(m.dataDir, manifest.Name)
+	if err := os.MkdirAll(extDataDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create extension data directory: %w", err)
+	}
+
+	ext := &LoadedExtension{
+		ID:        manifest.Name,
+		Manifest:  manifest,
+		Enabled:   false, // New extensions start disabled
+		DataDir:   extDataDir,
+		SourceDir: extDir,
+	}
+
+	// Initialize Goja VM
+	if err := m.initializeVM(ext); err != nil {
+		ext.Error = err.Error()
+		ext.Enabled = false
+		GoLog("[Extension] Failed to initialize VM for %s: %v\n", manifest.Name, err)
+	}
+
+	m.extensions[manifest.Name] = ext
+	GoLog("[Extension] Loaded extension: %s v%s\n", manifest.DisplayName, manifest.Version)
+
+	return ext, nil
+}
+
+func (m *ExtensionManager) initializeVM(ext *LoadedExtension) error {
+	vm := goja.New()
+	ext.VM = vm
+
+	indexPath := filepath.Join(ext.SourceDir, "index.js")
+	jsCode, err := os.ReadFile(indexPath)
+	if err != nil {
+		return fmt.Errorf("failed to read index.js: %w", err)
+	}
+
+	runtime := NewExtensionRuntime(ext)
+	runtime.RegisterAPIs(vm)
+	runtime.RegisterGoBackendAPIs(vm)
+
+	console := vm.NewObject()
+	console.Set("log", func(call goja.FunctionCall) goja.Value {
+		args := make([]interface{}, len(call.Arguments))
+		for i, arg := range call.Arguments {
+			args[i] = arg.Export()
+		}
+		GoLog("[Extension:%s] %v\n", ext.ID, args)
+		return goja.Undefined()
+	})
+	vm.Set("console", console)
+
+	var registeredExtension goja.Value
+	vm.Set("registerExtension", func(call goja.FunctionCall) goja.Value {
+		if len(call.Arguments) > 0 {
+			registeredExtension = call.Arguments[0]
+			vm.Set("extension", call.Arguments[0])
+		}
+		return goja.Undefined()
+	})
+
+	// Run the extension code
+	_, err = vm.RunString(string(jsCode))
+	if err != nil {
+		return fmt.Errorf("failed to execute extension code: %w", err)
+	}
+
+	// Verify extension was registered
+	if registeredExtension == nil || goja.IsUndefined(registeredExtension) {
+		return fmt.Errorf("extension did not call registerExtension()")
+	}
+
+	return nil
+}
+
+// UnloadExtension unloads an extension by ID
+func (m *ExtensionManager) UnloadExtension(extensionID string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return fmt.Errorf("Extension not found")
+	}
+
+	// Call cleanup if VM is initialized
+	if ext.VM != nil {
+		// Try to call cleanup function
+		cleanup, err := ext.VM.RunString("typeof extension !== 'undefined' && typeof extension.cleanup === 'function' ? extension.cleanup() : null")
+		if err != nil {
+			GoLog("[Extension] Error calling cleanup for %s: %v\n", extensionID, err)
+		} else if cleanup != nil && !goja.IsUndefined(cleanup) && !goja.IsNull(cleanup) {
+			GoLog("[Extension] Cleanup called for %s\n", extensionID)
+		}
+	}
+
+	// Remove from registry
+	delete(m.extensions, extensionID)
+	GoLog("[Extension] Unloaded extension: %s\n", extensionID)
+
+	return nil
+}
+
+// Returns error if extension not found (gomobile compatible)
+func (m *ExtensionManager) GetExtension(extensionID string) (*LoadedExtension, error) {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return nil, fmt.Errorf("Extension not found")
+	}
+	return ext, nil
+}
+
+// GetAllExtensions returns all loaded extensions
+func (m *ExtensionManager) GetAllExtensions() []*LoadedExtension {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	result := make([]*LoadedExtension, 0, len(m.extensions))
+	for _, ext := range m.extensions {
+		result = append(result, ext)
+	}
+	return result
+}
+
+func (m *ExtensionManager) SetExtensionEnabled(extensionID string, enabled bool) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return fmt.Errorf("Extension not found")
+	}
+
+	ext.Enabled = enabled
+	GoLog("[Extension] %s %s\n", extensionID, map[bool]string{true: "enabled", false: "disabled"}[enabled])
+
+	// Persist enabled state to settings store
+	store := GetExtensionSettingsStore()
+	if err := store.Set(extensionID, "_enabled", enabled); err != nil {
+		GoLog("[Extension] Failed to persist enabled state for %s: %v\n", extensionID, err)
+	}
+
+	return nil
+}
+
+// LoadExtensionsFromDirectory scans a directory and loads all valid extensions
+func (m *ExtensionManager) LoadExtensionsFromDirectory(dirPath string) ([]string, []error) {
+	var loaded []string
+	var errors []error
+
+	entries, err := os.ReadDir(dirPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return loaded, errors
+		}
+		return nil, []error{fmt.Errorf("failed to read extensions directory: %w", err)}
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			manifestPath := filepath.Join(dirPath, entry.Name(), "manifest.json")
+			if _, err := os.Stat(manifestPath); err == nil {
+				ext, err := m.loadExtensionFromDirectory(filepath.Join(dirPath, entry.Name()))
+				if err != nil {
+					GoLog("[Extension] Failed to load %s: %v\n", entry.Name(), err)
+					errors = append(errors, fmt.Errorf("%s: %w", entry.Name(), err))
+				} else {
+					loaded = append(loaded, ext.ID)
+				}
+			}
+		} else if strings.HasSuffix(strings.ToLower(entry.Name()), ".spotiflac-ext") {
+			ext, err := m.LoadExtensionFromFile(filepath.Join(dirPath, entry.Name()))
+			if err != nil {
+				GoLog("[Extension] Failed to load %s: %v\n", entry.Name(), err)
+				errors = append(errors, fmt.Errorf("%s: %w", entry.Name(), err))
+			} else {
+				loaded = append(loaded, ext.ID)
+			}
+		}
+	}
+
+	return loaded, errors
+}
+
+func (m *ExtensionManager) loadExtensionFromDirectory(dirPath string) (*LoadedExtension, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	manifestPath := filepath.Join(dirPath, "manifest.json")
+	manifestData, err := os.ReadFile(manifestPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read manifest.json: %w", err)
+	}
+
+	// Parse and validate manifest
+	manifest, err := ParseManifest(manifestData)
+	if err != nil {
+		return nil, fmt.Errorf("Invalid extension manifest: %w", err)
+	}
+
+	indexPath := filepath.Join(dirPath, "index.js")
+	if _, err := os.Stat(indexPath); os.IsNotExist(err) {
+		return nil, fmt.Errorf("Extension is missing index.js file")
+	}
+
+	if existing, exists := m.extensions[manifest.Name]; exists {
+		GoLog("[Extension] Extension '%s' already loaded, skipping\n", manifest.DisplayName)
+		return existing, nil
+	}
+
+	extDataDir := filepath.Join(m.dataDir, manifest.Name)
+	if err := os.MkdirAll(extDataDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create extension data directory: %w", err)
+	}
+
+	ext := &LoadedExtension{
+		ID:        manifest.Name,
+		Manifest:  manifest,
+		Enabled:   false, // Will be restored from settings store
+		DataDir:   extDataDir,
+		SourceDir: dirPath,
+	}
+
+	// Restore enabled state from settings store
+	store := GetExtensionSettingsStore()
+	if enabledVal, err := store.Get(manifest.Name, "_enabled"); err == nil {
+		if enabled, ok := enabledVal.(bool); ok {
+			ext.Enabled = enabled
+			GoLog("[Extension] Restored enabled state for %s: %v\n", manifest.Name, enabled)
+		}
+	}
+
+	// Initialize Goja VM
+	if err := m.initializeVM(ext); err != nil {
+		ext.Error = err.Error()
+		ext.Enabled = false
+		GoLog("[Extension] Failed to initialize VM for %s: %v\n", manifest.Name, err)
+	}
+
+	m.extensions[manifest.Name] = ext
+	GoLog("[Extension] Loaded extension: %s v%s\n", manifest.DisplayName, manifest.Version)
+
+	return ext, nil
+}
+
+// RemoveExtension completely removes an extension (unload + delete files)
+func (m *ExtensionManager) RemoveExtension(extensionID string) error {
+	ext, err := m.GetExtension(extensionID)
+	if err != nil {
+		return err
+	}
+
+	// Unload first
+	if err := m.UnloadExtension(extensionID); err != nil {
+		return err
+	}
+
+	// Remove source directory
+	if ext.SourceDir != "" {
+		if err := os.RemoveAll(ext.SourceDir); err != nil {
+			GoLog("[Extension] Warning: failed to remove source dir: %v\n", err)
+		}
+	}
+
+	// Optionally remove data directory (keep for now to preserve settings)
+	// if ext.DataDir != "" {
+	//     os.RemoveAll(ext.DataDir)
+	// }
+
+	return nil
+}
+
+// Only allows upgrades (new version > current version), not downgrades
+func (m *ExtensionManager) UpgradeExtension(filePath string) (*LoadedExtension, error) {
+	// Validate file extension
+	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
+		return nil, fmt.Errorf("Invalid file format. Please select a .spotiflac-ext file")
+	}
+
+	// Open the zip file
+	zipReader, err := zip.OpenReader(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("Cannot open extension file. The file may be corrupted or not a valid extension package")
+	}
+	defer zipReader.Close()
+
+	var manifestData []byte
+	var hasIndexJS bool
+	for _, file := range zipReader.File {
+		name := filepath.Base(file.Name)
+		if name == "manifest.json" {
+			rc, err := file.Open()
+			if err != nil {
+				return nil, fmt.Errorf("failed to open manifest.json: %w", err)
+			}
+			manifestData, err = io.ReadAll(rc)
+			rc.Close()
+			if err != nil {
+				return nil, fmt.Errorf("failed to read manifest.json: %w", err)
+			}
+		}
+		if name == "index.js" {
+			hasIndexJS = true
+		}
+	}
+
+	if manifestData == nil {
+		return nil, fmt.Errorf("Invalid extension package: manifest.json not found")
+	}
+
+	if !hasIndexJS {
+		return nil, fmt.Errorf("Invalid extension package: index.js not found")
+	}
+
+	newManifest, err := ParseManifest(manifestData)
+	if err != nil {
+		return nil, fmt.Errorf("Invalid extension manifest: %w", err)
+	}
+
+	m.mu.RLock()
+	existing, exists := m.extensions[newManifest.Name]
+	m.mu.RUnlock()
+
+	if !exists {
+		return nil, fmt.Errorf("Extension '%s' is not installed. Use install instead of upgrade.", newManifest.DisplayName)
+	}
+
+	// Compare versions - only allow upgrade, not downgrade
+	versionCompare := compareVersions(newManifest.Version, existing.Manifest.Version)
+	if versionCompare < 0 {
+		return nil, fmt.Errorf("Cannot downgrade extension. Current version: %s, New version: %s", existing.Manifest.Version, newManifest.Version)
+	}
+	if versionCompare == 0 {
+		return nil, fmt.Errorf("Extension is already at version %s", existing.Manifest.Version)
+	}
+
+	GoLog("[Extension] Upgrading %s from v%s to v%s\n", newManifest.DisplayName, existing.Manifest.Version, newManifest.Version)
+
+	// Save data directory path and enabled state (we want to preserve them)
+	extDataDir := existing.DataDir
+	extDir := existing.SourceDir
+	wasEnabled := existing.Enabled
+
+	// Cleanup and unload existing extension
+	m.CleanupExtension(existing.ID)
+	m.UnloadExtension(existing.ID)
+
+	// Remove old source files but keep data directory
+	if extDir != "" {
+		if err := os.RemoveAll(extDir); err != nil {
+			GoLog("[Extension] Warning: failed to remove old source dir: %v\n", err)
+		}
+	}
+
+	if err := os.MkdirAll(extDir, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create extension directory: %w", err)
+	}
+
+	for _, file := range zipReader.File {
+		if file.FileInfo().IsDir() {
+			continue
+		}
+
+		relPath := filepath.Clean(file.Name)
+		if strings.HasPrefix(relPath, "..") || filepath.IsAbs(relPath) {
+			GoLog("[Extension] Skipping unsafe path in archive: %s\n", file.Name)
+			continue
+		}
+		destPath := filepath.Join(extDir, relPath)
+
+		destDir := filepath.Dir(destPath)
+		if err := os.MkdirAll(destDir, 0755); err != nil {
+			return nil, fmt.Errorf("failed to create directory %s: %w", destDir, err)
+		}
+
+		destFile, err := os.Create(destPath)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create file %s: %w", destPath, err)
+		}
+
+		srcFile, err := file.Open()
+		if err != nil {
+			destFile.Close()
+			return nil, fmt.Errorf("failed to open file in archive: %w", err)
+		}
+
+		_, err = io.Copy(destFile, srcFile)
+		srcFile.Close()
+		destFile.Close()
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract file: %w", err)
+		}
+	}
+
+	ext := &LoadedExtension{
+		ID:        newManifest.Name,
+		Manifest:  newManifest,
+		Enabled:   wasEnabled, // Preserve enabled state from before upgrade
+		DataDir:   extDataDir,
+		SourceDir: extDir,
+	}
+
+	// Initialize Goja VM
+	if err := m.initializeVM(ext); err != nil {
+		ext.Error = err.Error()
+		ext.Enabled = false
+		GoLog("[Extension] Failed to initialize VM for %s: %v\n", newManifest.Name, err)
+	}
+
+	m.mu.Lock()
+	m.extensions[newManifest.Name] = ext
+	m.mu.Unlock()
+
+	GoLog("[Extension] Upgraded extension: %s to v%s\n", newManifest.DisplayName, newManifest.Version)
+
+	return ext, nil
+}
+
+type ExtensionUpgradeInfo struct {
+	ExtensionID    string `json:"extension_id"`
+	CurrentVersion string `json:"current_version"`
+	NewVersion     string `json:"new_version"`
+	CanUpgrade     bool   `json:"can_upgrade"`
+	IsInstalled    bool   `json:"is_installed"`
+}
+
+// checkExtensionUpgradeInternal checks if a package file is an upgrade for an existing extension
+// Internal function that returns struct
+func (m *ExtensionManager) checkExtensionUpgradeInternal(filePath string) (*ExtensionUpgradeInfo, error) {
+	// Validate file extension
+	if !strings.HasSuffix(strings.ToLower(filePath), ".spotiflac-ext") {
+		return nil, fmt.Errorf("Invalid file format")
+	}
+
+	// Open the zip file
+	zipReader, err := zip.OpenReader(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("Cannot open extension file")
+	}
+	defer zipReader.Close()
+
+	var manifestData []byte
+	for _, file := range zipReader.File {
+		name := filepath.Base(file.Name)
+		if name == "manifest.json" {
+			rc, err := file.Open()
+			if err != nil {
+				return nil, fmt.Errorf("failed to open manifest.json")
+			}
+			manifestData, err = io.ReadAll(rc)
+			rc.Close()
+			if err != nil {
+				return nil, fmt.Errorf("failed to read manifest.json")
+			}
+			break
+		}
+	}
+
+	if manifestData == nil {
+		return nil, fmt.Errorf("manifest.json not found")
+	}
+
+	newManifest, err := ParseManifest(manifestData)
+	if err != nil {
+		return nil, fmt.Errorf("Invalid manifest: %w", err)
+	}
+
+	m.mu.RLock()
+	existing, exists := m.extensions[newManifest.Name]
+	m.mu.RUnlock()
+
+	info := &ExtensionUpgradeInfo{
+		ExtensionID: newManifest.Name,
+		NewVersion:  newManifest.Version,
+		IsInstalled: exists,
+	}
+
+	if !exists {
+		// Not installed - this is a new install, not upgrade
+		info.CurrentVersion = ""
+		info.CanUpgrade = false
+	} else {
+		info.CurrentVersion = existing.Manifest.Version
+		info.CanUpgrade = compareVersions(newManifest.Version, existing.Manifest.Version) > 0
+	}
+
+	return info, nil
+}
+
+func (m *ExtensionManager) CheckExtensionUpgradeJSON(filePath string) (string, error) {
+	info, err := m.checkExtensionUpgradeInternal(filePath)
+	if err != nil {
+		return "", err
+	}
+
+	jsonBytes, err := json.Marshal(info)
+	if err != nil {
+		return "", err
+	}
+
+	return string(jsonBytes), nil
+}
+
+// GetInstalledExtensionsJSON returns all extensions as JSON for Flutter
+func (m *ExtensionManager) GetInstalledExtensionsJSON() (string, error) {
+	extensions := m.GetAllExtensions()
+
+	type ExtensionInfo struct {
+		ID                     string                `json:"id"`
+		Name                   string                `json:"name"`
+		DisplayName            string                `json:"display_name"`
+		Version                string                `json:"version"`
+		Author                 string                `json:"author"`
+		Description            string                `json:"description"`
+		Homepage               string                `json:"homepage,omitempty"`
+		IconPath               string                `json:"icon_path,omitempty"`
+		Types                  []ExtensionType       `json:"types"`
+		Enabled                bool                  `json:"enabled"`
+		Status                 string                `json:"status"`
+		Error                  string                `json:"error_message,omitempty"`
+		Settings               []ExtensionSetting    `json:"settings,omitempty"`
+		QualityOptions         []QualityOption       `json:"quality_options,omitempty"`
+		Permissions            []string              `json:"permissions"`
+		HasMetadataProvider    bool                  `json:"has_metadata_provider"`
+		HasDownloadProvider    bool                  `json:"has_download_provider"`
+		SkipMetadataEnrichment bool                  `json:"skip_metadata_enrichment"`
+		SearchBehavior         *SearchBehaviorConfig `json:"search_behavior,omitempty"`
+		TrackMatching          *TrackMatchingConfig  `json:"track_matching,omitempty"`
+		PostProcessing         *PostProcessingConfig `json:"post_processing,omitempty"`
+	}
+
+	infos := make([]ExtensionInfo, len(extensions))
+	for i, ext := range extensions {
+		permissions := []string{}
+		for _, domain := range ext.Manifest.Permissions.Network {
+			permissions = append(permissions, "network:"+domain)
+		}
+		if ext.Manifest.Permissions.Storage {
+			permissions = append(permissions, "storage:enabled")
+		}
+
+		// Determine status
+		status := "loaded"
+		if ext.Error != "" {
+			status = "error"
+		} else if !ext.Enabled {
+			status = "disabled"
+		}
+
+		iconPath := ""
+		if ext.Manifest.Icon != "" && ext.SourceDir != "" {
+			possibleIcon := filepath.Join(ext.SourceDir, ext.Manifest.Icon)
+			if _, err := os.Stat(possibleIcon); err == nil {
+				iconPath = possibleIcon
+			}
+		}
+		if iconPath == "" && ext.SourceDir != "" {
+			possibleIcon := filepath.Join(ext.SourceDir, "icon.png")
+			if _, err := os.Stat(possibleIcon); err == nil {
+				iconPath = possibleIcon
+			}
+		}
+
+		infos[i] = ExtensionInfo{
+			ID:                     ext.ID,
+			Name:                   ext.Manifest.Name,
+			DisplayName:            ext.Manifest.DisplayName,
+			Version:                ext.Manifest.Version,
+			Author:                 ext.Manifest.Author,
+			Description:            ext.Manifest.Description,
+			Homepage:               ext.Manifest.Homepage,
+			IconPath:               iconPath,
+			Types:                  ext.Manifest.Types,
+			Enabled:                ext.Enabled,
+			Status:                 status,
+			Error:                  ext.Error,
+			Settings:               ext.Manifest.Settings,
+			QualityOptions:         ext.Manifest.QualityOptions,
+			Permissions:            permissions,
+			HasMetadataProvider:    ext.Manifest.IsMetadataProvider(),
+			HasDownloadProvider:    ext.Manifest.IsDownloadProvider(),
+			SkipMetadataEnrichment: ext.Manifest.SkipMetadataEnrichment,
+			SearchBehavior:         ext.Manifest.SearchBehavior,
+			TrackMatching:          ext.Manifest.TrackMatching,
+			PostProcessing:         ext.Manifest.PostProcessing,
+		}
+	}
+
+	jsonBytes, err := json.Marshal(infos)
+	if err != nil {
+		return "", err
+	}
+
+	return string(jsonBytes), nil
+}
+
+// ==================== Extension Lifecycle ====================
+
+func (m *ExtensionManager) InitializeExtension(extensionID string, settings map[string]interface{}) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return fmt.Errorf("Extension not found")
+	}
+
+	if ext.VM == nil {
+		return fmt.Errorf("Extension failed to load. Please reinstall the extension")
+	}
+
+	settingsJSON, err := json.Marshal(settings)
+	if err != nil {
+		return fmt.Errorf("Failed to save settings")
+	}
+
+	script := fmt.Sprintf(`
+		(function() {
+			var settings = %s;
+			if (typeof extension !== 'undefined' && typeof extension.initialize === 'function') {
+				try {
+					extension.initialize(settings);
+					return { success: true };
+				} catch (e) {
+					return { success: false, error: e.toString() };
+				}
+			}
+			return { success: true, message: 'no initialize function' };
+		})()
+	`, string(settingsJSON))
+
+	result, err := ext.VM.RunString(script)
+	if err != nil {
+		ext.Error = fmt.Sprintf("initialize failed: %v", err)
+		ext.Enabled = false
+		GoLog("[Extension] Initialize error for %s: %v\n", extensionID, err)
+		return err
+	}
+
+	if result != nil && !goja.IsUndefined(result) {
+		exported := result.Export()
+		if resultMap, ok := exported.(map[string]interface{}); ok {
+			if success, ok := resultMap["success"].(bool); ok && !success {
+				errMsg := "unknown error"
+				if e, ok := resultMap["error"].(string); ok {
+					errMsg = e
+				}
+				ext.Error = errMsg
+				ext.Enabled = false
+				GoLog("[Extension] Initialize failed for %s: %s\n", extensionID, errMsg)
+				return fmt.Errorf("initialize failed: %s", errMsg)
+			}
+		}
+	}
+
+	GoLog("[Extension] Initialized %s\n", extensionID)
+	return nil
+}
+
+func (m *ExtensionManager) CleanupExtension(extensionID string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return fmt.Errorf("Extension not found")
+	}
+
+	if ext.VM == nil {
+		return nil
+	}
+
+	script := `
+		(function() {
+			if (typeof extension !== 'undefined' && typeof extension.cleanup === 'function') {
+				try {
+					extension.cleanup();
+					return { success: true };
+				} catch (e) {
+					return { success: false, error: e.toString() };
+				}
+			}
+			return { success: true, message: 'no cleanup function' };
+		})()
+	`
+
+	result, err := ext.VM.RunString(script)
+	if err != nil {
+		GoLog("[Extension] Cleanup error for %s: %v\n", extensionID, err)
+		return err
+	}
+
+	if result != nil && !goja.IsUndefined(result) {
+		exported := result.Export()
+		if resultMap, ok := exported.(map[string]interface{}); ok {
+			if success, ok := resultMap["success"].(bool); ok && !success {
+				errMsg := "unknown error"
+				if e, ok := resultMap["error"].(string); ok {
+					errMsg = e
+				}
+				GoLog("[Extension] Cleanup failed for %s: %s\n", extensionID, errMsg)
+				return fmt.Errorf("cleanup failed: %s", errMsg)
+			}
+		}
+	}
+
+	GoLog("[Extension] Cleaned up %s\n", extensionID)
+	return nil
+}
+
+// UnloadAllExtensions unloads all extensions gracefully
+func (m *ExtensionManager) UnloadAllExtensions() {
+	m.mu.Lock()
+	extensionIDs := make([]string, 0, len(m.extensions))
+	for id := range m.extensions {
+		extensionIDs = append(extensionIDs, id)
+	}
+	m.mu.Unlock()
+
+	for _, id := range extensionIDs {
+		m.CleanupExtension(id)
+		m.UnloadExtension(id)
+	}
+
+	GoLog("[Extension] All extensions unloaded\n")
+}
+
+// The function is called as extension.<actionName>() and can return a result
+func (m *ExtensionManager) InvokeAction(extensionID string, actionName string) (map[string]interface{}, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	ext, exists := m.extensions[extensionID]
+	if !exists {
+		return nil, fmt.Errorf("extension not found: %s", extensionID)
+	}
+
+	if ext.VM == nil {
+		return nil, fmt.Errorf("extension VM not initialized")
+	}
+
+	if !ext.Enabled {
+		return nil, fmt.Errorf("extension is disabled")
+	}
+
+	// Call the action function on the extension object
+	script := fmt.Sprintf(`
+		(function() {
+			if (typeof extension !== 'undefined' && typeof extension.%s === 'function') {
+				try {
+					var result = extension.%s();
+					if (result && typeof result.then === 'function') {
+						// Handle promise - return pending status
+						return { success: true, pending: true, message: 'Action started' };
+					}
+					return { success: true, result: result };
+				} catch (e) {
+					return { success: false, error: e.toString() };
+				}
+			}
+			return { success: false, error: 'Action function not found: %s' };
+		})()
+	`, actionName, actionName, actionName)
+
+	result, err := RunWithTimeoutAndRecover(ext.VM, script, DefaultJSTimeout)
+	if err != nil {
+		GoLog("[Extension] InvokeAction error for %s.%s: %v\n", extensionID, actionName, err)
+		return nil, fmt.Errorf("action failed: %v", err)
+	}
+
+	if result == nil || goja.IsUndefined(result) {
+		return map[string]interface{}{"success": true}, nil
+	}
+
+	exported := result.Export()
+	if resultMap, ok := exported.(map[string]interface{}); ok {
+		GoLog("[Extension] InvokeAction %s.%s result: %v\n", extensionID, actionName, resultMap)
+		return resultMap, nil
+	}
+
+	return map[string]interface{}{"success": true, "result": exported}, nil
+}

go_backend/extension_manifest.go

@@ -0,0 +1,306 @@
+// Package gobackend provides extension manifest parsing and validation
+package gobackend
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// ExtensionType represents the type of extension
+type ExtensionType string
+
+const (
+	ExtensionTypeMetadataProvider ExtensionType = "metadata_provider"
+	ExtensionTypeDownloadProvider ExtensionType = "download_provider"
+)
+
+// SettingType represents the type of a setting field
+type SettingType string
+
+const (
+	SettingTypeString SettingType = "string"
+	SettingTypeNumber SettingType = "number"
+	SettingTypeBool   SettingType = "boolean"
+	SettingTypeSelect SettingType = "select"
+	SettingTypeButton SettingType = "button" // Action button that calls a JS function
+)
+
+// ExtensionPermissions defines what resources an extension can access
+type ExtensionPermissions struct {
+	Network []string `json:"network"` // List of allowed domains
+	Storage bool     `json:"storage"` // Whether extension can use storage API
+	File    bool     `json:"file"`    // Whether extension can use file API
+}
+
+// ExtensionSetting defines a configurable setting for an extension
+type ExtensionSetting struct {
+	Key         string      `json:"key"`
+	Type        SettingType `json:"type"`
+	Label       string      `json:"label"`
+	Description string      `json:"description,omitempty"`
+	Required    bool        `json:"required,omitempty"`
+	Secret      bool        `json:"secret,omitempty"`
+	Default     interface{} `json:"default,omitempty"`
+	Options     []string    `json:"options,omitempty"` // For select type
+	Action      string      `json:"action,omitempty"`  // For button type: JS function name to call (e.g., "startLogin")
+}
+
+// QualityOption represents a quality option for download providers
+type QualityOption struct {
+	ID          string                   `json:"id"`                 // Unique identifier (e.g., "mp3_320", "opus_128")
+	Label       string                   `json:"label"`              // Display name (e.g., "MP3 320kbps")
+	Description string                   `json:"description"`        // Optional description (e.g., "Best quality MP3")
+	Settings    []QualitySpecificSetting `json:"settings,omitempty"` // Quality-specific settings
+}
+
+// QualitySpecificSetting represents a setting that's specific to a quality option
+type QualitySpecificSetting struct {
+	Key         string      `json:"key"`
+	Type        SettingType `json:"type"`
+	Label       string      `json:"label"`
+	Description string      `json:"description,omitempty"`
+	Required    bool        `json:"required,omitempty"`
+	Secret      bool        `json:"secret,omitempty"`
+	Default     interface{} `json:"default,omitempty"`
+	Options     []string    `json:"options,omitempty"` // For select type
+}
+
+// SearchBehaviorConfig defines custom search behavior for an extension
+type SearchBehaviorConfig struct {
+	Enabled         bool   `json:"enabled"`                   // Whether extension provides custom search
+	Placeholder     string `json:"placeholder,omitempty"`     // Placeholder text for search box
+	Primary         bool   `json:"primary,omitempty"`         // If true, show as primary search tab
+	Icon            string `json:"icon,omitempty"`            // Icon for search tab
+	ThumbnailRatio  string `json:"thumbnailRatio,omitempty"`  // Thumbnail aspect ratio: "square" (1:1), "wide" (16:9), "portrait" (2:3)
+	ThumbnailWidth  int    `json:"thumbnailWidth,omitempty"`  // Custom thumbnail width in pixels
+	ThumbnailHeight int    `json:"thumbnailHeight,omitempty"` // Custom thumbnail height in pixels
+}
+
+// URLHandlerConfig defines custom URL handling for an extension
+type URLHandlerConfig struct {
+	Enabled  bool     `json:"enabled"`            // Whether extension handles URLs
+	Patterns []string `json:"patterns,omitempty"` // URL patterns to match (e.g., "music.youtube.com", "soundcloud.com")
+}
+
+// TrackMatchingConfig defines custom track matching behavior
+type TrackMatchingConfig struct {
+	CustomMatching    bool   `json:"customMatching"`              // Whether extension handles matching
+	Strategy          string `json:"strategy,omitempty"`          // "isrc", "name", "duration", "custom"
+	DurationTolerance int    `json:"durationTolerance,omitempty"` // Tolerance in seconds for duration matching
+}
+
+// PostProcessingHook defines a post-processing hook
+type PostProcessingHook struct {
+	ID               string   `json:"id"`                         // Unique identifier
+	Name             string   `json:"name"`                       // Display name
+	Description      string   `json:"description,omitempty"`      // Description
+	DefaultEnabled   bool     `json:"defaultEnabled,omitempty"`   // Whether enabled by default
+	SupportedFormats []string `json:"supportedFormats,omitempty"` // Supported file formats (e.g., ["flac", "mp3"])
+}
+
+// PostProcessingConfig defines post-processing capabilities
+type PostProcessingConfig struct {
+	Enabled bool                 `json:"enabled"`         // Whether extension provides post-processing
+	Hooks   []PostProcessingHook `json:"hooks,omitempty"` // Available hooks
+}
+
+// ExtensionManifest represents the manifest.json of an extension
+type ExtensionManifest struct {
+	Name                   string                `json:"name"`
+	DisplayName            string                `json:"displayName"`
+	Version                string                `json:"version"`
+	Author                 string                `json:"author"`
+	Description            string                `json:"description"`
+	Homepage               string                `json:"homepage,omitempty"`
+	Icon                   string                `json:"icon,omitempty"` // Icon filename (e.g., "icon.png")
+	Types                  []ExtensionType       `json:"type"`
+	Permissions            ExtensionPermissions  `json:"permissions"`
+	Settings               []ExtensionSetting    `json:"settings,omitempty"`
+	QualityOptions         []QualityOption       `json:"qualityOptions,omitempty"` // Custom quality options for download providers
+	MinAppVersion          string                `json:"minAppVersion,omitempty"`
+	SkipMetadataEnrichment bool                  `json:"skipMetadataEnrichment,omitempty"` // If true, don't enrich metadata from Deezer/Spotify
+	SkipBuiltInFallback    bool                  `json:"skipBuiltInFallback,omitempty"`    // If true, don't fallback to built-in providers (tidal/qobuz/amazon)
+	SearchBehavior         *SearchBehaviorConfig `json:"searchBehavior,omitempty"`         // Custom search behavior
+	URLHandler             *URLHandlerConfig     `json:"urlHandler,omitempty"`             // Custom URL handling
+	TrackMatching          *TrackMatchingConfig  `json:"trackMatching,omitempty"`          // Custom track matching
+	PostProcessing         *PostProcessingConfig `json:"postProcessing,omitempty"`         // Post-processing hooks
+}
+
+// ManifestValidationError represents a validation error in the manifest
+type ManifestValidationError struct {
+	Field   string
+	Message string
+}
+
+func (e *ManifestValidationError) Error() string {
+	return fmt.Sprintf("manifest validation error: %s - %s", e.Field, e.Message)
+}
+
+// ParseManifest parses and validates a manifest from JSON bytes
+func ParseManifest(data []byte) (*ExtensionManifest, error) {
+	var manifest ExtensionManifest
+	if err := json.Unmarshal(data, &manifest); err != nil {
+		return nil, fmt.Errorf("failed to parse manifest JSON: %w", err)
+	}
+
+	if err := manifest.Validate(); err != nil {
+		return nil, err
+	}
+
+	return &manifest, nil
+}
+
+func (m *ExtensionManifest) Validate() error {
+	if strings.TrimSpace(m.Name) == "" {
+		return &ManifestValidationError{Field: "name", Message: "name is required"}
+	}
+
+	if strings.TrimSpace(m.Version) == "" {
+		return &ManifestValidationError{Field: "version", Message: "version is required"}
+	}
+
+	if strings.TrimSpace(m.Author) == "" {
+		return &ManifestValidationError{Field: "author", Message: "author is required"}
+	}
+
+	if strings.TrimSpace(m.Description) == "" {
+		return &ManifestValidationError{Field: "description", Message: "description is required"}
+	}
+
+	if len(m.Types) == 0 {
+		return &ManifestValidationError{Field: "type", Message: "at least one type is required"}
+	}
+
+	for _, t := range m.Types {
+		if t != ExtensionTypeMetadataProvider && t != ExtensionTypeDownloadProvider {
+			return &ManifestValidationError{
+				Field:   "type",
+				Message: fmt.Sprintf("invalid extension type: %s (must be 'metadata_provider' or 'download_provider')", t),
+			}
+		}
+	}
+
+	// Validate settings if present
+	for i, setting := range m.Settings {
+		if strings.TrimSpace(setting.Key) == "" {
+			return &ManifestValidationError{
+				Field:   fmt.Sprintf("settings[%d].key", i),
+				Message: "setting key is required",
+			}
+		}
+
+		if setting.Type == "" {
+			return &ManifestValidationError{
+				Field:   fmt.Sprintf("settings[%d].type", i),
+				Message: "setting type is required",
+			}
+		}
+
+		// Select type requires options
+		if setting.Type == SettingTypeSelect && len(setting.Options) == 0 {
+			return &ManifestValidationError{
+				Field:   fmt.Sprintf("settings[%d].options", i),
+				Message: "select type requires options",
+			}
+		}
+
+		if setting.Type == SettingTypeButton && setting.Action == "" {
+			return &ManifestValidationError{
+				Field:   fmt.Sprintf("settings[%d].action", i),
+				Message: "button type requires action (JS function name)",
+			}
+		}
+	}
+
+	return nil
+}
+
+// HasType checks if the extension has a specific type
+func (m *ExtensionManifest) HasType(t ExtensionType) bool {
+	for _, et := range m.Types {
+		if et == t {
+			return true
+		}
+	}
+	return false
+}
+
+// IsMetadataProvider returns true if extension provides metadata
+func (m *ExtensionManifest) IsMetadataProvider() bool {
+	return m.HasType(ExtensionTypeMetadataProvider)
+}
+
+// IsDownloadProvider returns true if extension provides downloads
+func (m *ExtensionManifest) IsDownloadProvider() bool {
+	return m.HasType(ExtensionTypeDownloadProvider)
+}
+
+// IsDomainAllowed checks if a domain is in the allowed network permissions
+func (m *ExtensionManifest) IsDomainAllowed(domain string) bool {
+	domain = strings.ToLower(strings.TrimSpace(domain))
+	for _, allowed := range m.Permissions.Network {
+		allowed = strings.ToLower(strings.TrimSpace(allowed))
+		if allowed == domain {
+			return true
+		}
+		// Support wildcard subdomains (e.g., *.example.com)
+		if strings.HasPrefix(allowed, "*.") {
+			suffix := allowed[1:] // Remove the *
+			if strings.HasSuffix(domain, suffix) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// HasCustomSearch returns true if extension provides custom search
+func (m *ExtensionManifest) HasCustomSearch() bool {
+	return m.SearchBehavior != nil && m.SearchBehavior.Enabled
+}
+
+// HasCustomMatching returns true if extension provides custom track matching
+func (m *ExtensionManifest) HasCustomMatching() bool {
+	return m.TrackMatching != nil && m.TrackMatching.CustomMatching
+}
+
+// HasPostProcessing returns true if extension provides post-processing
+func (m *ExtensionManifest) HasPostProcessing() bool {
+	return m.PostProcessing != nil && m.PostProcessing.Enabled
+}
+
+// HasURLHandler returns true if extension handles custom URLs
+func (m *ExtensionManifest) HasURLHandler() bool {
+	return m.URLHandler != nil && m.URLHandler.Enabled && len(m.URLHandler.Patterns) > 0
+}
+
+// MatchesURL checks if a URL matches any of the extension's URL patterns
+func (m *ExtensionManifest) MatchesURL(urlStr string) bool {
+	if !m.HasURLHandler() {
+		return false
+	}
+
+	urlStr = strings.ToLower(strings.TrimSpace(urlStr))
+	for _, pattern := range m.URLHandler.Patterns {
+		pattern = strings.ToLower(strings.TrimSpace(pattern))
+		// Check if URL contains the pattern (host match)
+		if strings.Contains(urlStr, pattern) {
+			return true
+		}
+	}
+	return false
+}
+
+// GetPostProcessingHooks returns all post-processing hooks
+func (m *ExtensionManifest) GetPostProcessingHooks() []PostProcessingHook {
+	if m.PostProcessing == nil {
+		return nil
+	}
+	return m.PostProcessing.Hooks
+}
+
+// ToJSON serializes the manifest to JSON
+func (m *ExtensionManifest) ToJSON() ([]byte, error) {
+	return json.Marshal(m)
+}

go_backend/extension_runtime.go

@@ -0,0 +1,315 @@
+package gobackend
+
+import (
+	"net/http"
+	"net/url"
+	"sync"
+	"time"
+
+	"github.com/dop251/goja"
+)
+
+const DefaultJSTimeout = 30 * time.Second
+
+var (
+	extensionAuthState   = make(map[string]*ExtensionAuthState)
+	extensionAuthStateMu sync.RWMutex
+)
+
+type ExtensionAuthState struct {
+	PendingAuthURL  string
+	AuthCode        string
+	AccessToken     string
+	RefreshToken    string
+	ExpiresAt       time.Time
+	IsAuthenticated bool
+	// PKCE support
+	PKCEVerifier  string
+	PKCEChallenge string
+}
+
+type PendingAuthRequest struct {
+	ExtensionID string
+	AuthURL     string
+	CallbackURL string
+}
+
+var (
+	pendingAuthRequests   = make(map[string]*PendingAuthRequest)
+	pendingAuthRequestsMu sync.RWMutex
+)
+
+// GetPendingAuthRequest returns pending auth request for an extension (called from Flutter)
+func GetPendingAuthRequest(extensionID string) *PendingAuthRequest {
+	pendingAuthRequestsMu.RLock()
+	defer pendingAuthRequestsMu.RUnlock()
+	return pendingAuthRequests[extensionID]
+}
+
+func ClearPendingAuthRequest(extensionID string) {
+	pendingAuthRequestsMu.Lock()
+	defer pendingAuthRequestsMu.Unlock()
+	delete(pendingAuthRequests, extensionID)
+}
+
+func SetExtensionAuthCode(extensionID string, authCode string) {
+	extensionAuthStateMu.Lock()
+	defer extensionAuthStateMu.Unlock()
+
+	state, exists := extensionAuthState[extensionID]
+	if !exists {
+		state = &ExtensionAuthState{}
+		extensionAuthState[extensionID] = state
+	}
+	state.AuthCode = authCode
+}
+
+func SetExtensionTokens(extensionID string, accessToken, refreshToken string, expiresAt time.Time) {
+	extensionAuthStateMu.Lock()
+	defer extensionAuthStateMu.Unlock()
+
+	state, exists := extensionAuthState[extensionID]
+	if !exists {
+		state = &ExtensionAuthState{}
+		extensionAuthState[extensionID] = state
+	}
+	state.AccessToken = accessToken
+	state.RefreshToken = refreshToken
+	state.ExpiresAt = expiresAt
+	state.IsAuthenticated = accessToken != ""
+}
+
+type ExtensionRuntime struct {
+	extensionID string
+	manifest    *ExtensionManifest
+	settings    map[string]interface{}
+	httpClient  *http.Client
+	cookieJar   http.CookieJar
+	dataDir     string
+	vm          *goja.Runtime
+}
+
+func NewExtensionRuntime(ext *LoadedExtension) *ExtensionRuntime {
+	jar, _ := newSimpleCookieJar()
+
+	runtime := &ExtensionRuntime{
+		extensionID: ext.ID,
+		manifest:    ext.Manifest,
+		settings:    make(map[string]interface{}),
+		cookieJar:   jar,
+		dataDir:     ext.DataDir,
+		vm:          ext.VM,
+	}
+
+	client := &http.Client{
+		Timeout: 30 * time.Second,
+		Jar:     jar,
+		CheckRedirect: func(req *http.Request, via []*http.Request) error {
+			// Validate redirect target domain against allowed domains
+			domain := req.URL.Hostname()
+			if !ext.Manifest.IsDomainAllowed(domain) {
+				GoLog("[Extension:%s] Redirect blocked: domain '%s' not in allowed list\n", ext.ID, domain)
+				return &RedirectBlockedError{Domain: domain}
+			}
+			if isPrivateIP(domain) {
+				GoLog("[Extension:%s] Redirect blocked: private IP '%s'\n", ext.ID, domain)
+				return &RedirectBlockedError{Domain: domain, IsPrivate: true}
+			}
+			// Default redirect limit (10)
+			if len(via) >= 10 {
+				return http.ErrUseLastResponse
+			}
+			return nil
+		},
+	}
+	runtime.httpClient = client
+
+	return runtime
+}
+
+type RedirectBlockedError struct {
+	Domain    string
+	IsPrivate bool
+}
+
+func (e *RedirectBlockedError) Error() string {
+	if e.IsPrivate {
+		return "redirect blocked: private/local network access denied"
+	}
+	return "redirect blocked: domain '" + e.Domain + "' not in allowed list"
+}
+
+// isPrivateIP checks if a hostname resolves to a private/local IP address
+func isPrivateIP(host string) bool {
+	// Block common private network patterns
+	// This is a simple check - for production, consider DNS resolution
+	privatePatterns := []string{
+		"localhost",
+		"127.",
+		"10.",
+		"172.16.", "172.17.", "172.18.", "172.19.",
+		"172.20.", "172.21.", "172.22.", "172.23.",
+		"172.24.", "172.25.", "172.26.", "172.27.",
+		"172.28.", "172.29.", "172.30.", "172.31.",
+		"192.168.",
+		"169.254.",
+		"::1",
+		"fc00:",
+		"fe80:",
+	}
+
+	hostLower := host
+	for _, pattern := range privatePatterns {
+		if hostLower == pattern || len(hostLower) > len(pattern) && hostLower[:len(pattern)] == pattern {
+			return true
+		}
+	}
+
+	// Also block .local domains
+	if len(host) > 6 && host[len(host)-6:] == ".local" {
+		return true
+	}
+
+	return false
+}
+
+type simpleCookieJar struct {
+	cookies map[string][]*http.Cookie
+	mu      sync.RWMutex
+}
+
+func newSimpleCookieJar() (*simpleCookieJar, error) {
+	return &simpleCookieJar{
+		cookies: make(map[string][]*http.Cookie),
+	}, nil
+}
+
+func (j *simpleCookieJar) SetCookies(u *url.URL, cookies []*http.Cookie) {
+	j.mu.Lock()
+	defer j.mu.Unlock()
+	key := u.Host
+	j.cookies[key] = append(j.cookies[key], cookies...)
+}
+
+func (j *simpleCookieJar) Cookies(u *url.URL) []*http.Cookie {
+	j.mu.RLock()
+	defer j.mu.RUnlock()
+	return j.cookies[u.Host]
+}
+
+func (r *ExtensionRuntime) SetSettings(settings map[string]interface{}) {
+	r.settings = settings
+}
+
+// RegisterAPIs registers all sandboxed APIs to the Goja VM
+func (r *ExtensionRuntime) RegisterAPIs(vm *goja.Runtime) {
+	r.vm = vm
+
+	// HTTP client (sandboxed to allowed domains)
+	httpObj := vm.NewObject()
+	httpObj.Set("get", r.httpGet)
+	httpObj.Set("post", r.httpPost)
+	httpObj.Set("put", r.httpPut)
+	httpObj.Set("delete", r.httpDelete)
+	httpObj.Set("patch", r.httpPatch)
+	httpObj.Set("request", r.httpRequest) // Generic HTTP request (GET, POST, PUT, DELETE, etc.)
+	httpObj.Set("clearCookies", r.httpClearCookies)
+	vm.Set("http", httpObj)
+
+	storageObj := vm.NewObject()
+	storageObj.Set("get", r.storageGet)
+	storageObj.Set("set", r.storageSet)
+	storageObj.Set("remove", r.storageRemove)
+	vm.Set("storage", storageObj)
+
+	// Secure Credentials API (encrypted storage for sensitive data)
+	credentialsObj := vm.NewObject()
+	credentialsObj.Set("store", r.credentialsStore)
+	credentialsObj.Set("get", r.credentialsGet)
+	credentialsObj.Set("remove", r.credentialsRemove)
+	credentialsObj.Set("has", r.credentialsHas)
+	vm.Set("credentials", credentialsObj)
+
+	authObj := vm.NewObject()
+	authObj.Set("openAuthUrl", r.authOpenUrl)
+	authObj.Set("getAuthCode", r.authGetCode)
+	authObj.Set("setAuthCode", r.authSetCode)
+	authObj.Set("clearAuth", r.authClear)
+	authObj.Set("isAuthenticated", r.authIsAuthenticated)
+	authObj.Set("getTokens", r.authGetTokens)
+	// PKCE support
+	authObj.Set("generatePKCE", r.authGeneratePKCE)
+	authObj.Set("getPKCE", r.authGetPKCE)
+	authObj.Set("startOAuthWithPKCE", r.authStartOAuthWithPKCE)
+	authObj.Set("exchangeCodeWithPKCE", r.authExchangeCodeWithPKCE)
+	vm.Set("auth", authObj)
+
+	// File operations (sandboxed)
+	fileObj := vm.NewObject()
+	fileObj.Set("download", r.fileDownload)
+	fileObj.Set("exists", r.fileExists)
+	fileObj.Set("delete", r.fileDelete)
+	fileObj.Set("read", r.fileRead)
+	fileObj.Set("write", r.fileWrite)
+	fileObj.Set("copy", r.fileCopy)
+	fileObj.Set("move", r.fileMove)
+	fileObj.Set("getSize", r.fileGetSize)
+	vm.Set("file", fileObj)
+
+	ffmpegObj := vm.NewObject()
+	ffmpegObj.Set("execute", r.ffmpegExecute)
+	ffmpegObj.Set("getInfo", r.ffmpegGetInfo)
+	ffmpegObj.Set("convert", r.ffmpegConvert)
+	vm.Set("ffmpeg", ffmpegObj)
+
+	// Track matching API
+	matchingObj := vm.NewObject()
+	matchingObj.Set("compareStrings", r.matchingCompareStrings)
+	matchingObj.Set("compareDuration", r.matchingCompareDuration)
+	matchingObj.Set("normalizeString", r.matchingNormalizeString)
+	vm.Set("matching", matchingObj)
+
+	utilsObj := vm.NewObject()
+	utilsObj.Set("base64Encode", r.base64Encode)
+	utilsObj.Set("base64Decode", r.base64Decode)
+	utilsObj.Set("md5", r.md5Hash)
+	utilsObj.Set("sha256", r.sha256Hash)
+	utilsObj.Set("hmacSHA256", r.hmacSHA256)
+	utilsObj.Set("hmacSHA256Base64", r.hmacSHA256Base64)
+	utilsObj.Set("hmacSHA1", r.hmacSHA1)
+	utilsObj.Set("parseJSON", r.parseJSON)
+	utilsObj.Set("stringifyJSON", r.stringifyJSON)
+	// Crypto utilities for developers
+	utilsObj.Set("encrypt", r.cryptoEncrypt)
+	utilsObj.Set("decrypt", r.cryptoDecrypt)
+	utilsObj.Set("generateKey", r.cryptoGenerateKey)
+	utilsObj.Set("randomUserAgent", r.randomUserAgent)
+	vm.Set("utils", utilsObj)
+
+	// Log object (already set in extension_manager.go, but we can enhance it)
+	logObj := vm.NewObject()
+	logObj.Set("debug", r.logDebug)
+	logObj.Set("info", r.logInfo)
+	logObj.Set("warn", r.logWarn)
+	logObj.Set("error", r.logError)
+	vm.Set("log", logObj)
+
+	gobackendObj := vm.NewObject()
+	gobackendObj.Set("sanitizeFilename", r.sanitizeFilenameWrapper)
+	vm.Set("gobackend", gobackendObj)
+
+	// ==================== Browser-like Polyfills ====================
+	// These make porting browser/Node.js libraries easier
+
+	// Global fetch() - Promise-style HTTP API (browser-compatible)
+	vm.Set("fetch", r.fetchPolyfill)
+
+	vm.Set("atob", r.atobPolyfill)
+	vm.Set("btoa", r.btoaPolyfill)
+
+	r.registerTextEncoderDecoder(vm)
+
+	r.registerURLClass(vm)
+
+	r.registerJSONGlobal(vm)
+}

go_backend/extension_runtime_auth.go

@@ -0,0 +1,520 @@
+// Package gobackend provides Auth API and PKCE support for extension runtime
+package gobackend
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"github.com/dop251/goja"
+)
+
+// ==================== Auth API (OAuth Support) ====================
+
+func (r *ExtensionRuntime) authOpenUrl(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "auth URL is required",
+		})
+	}
+
+	authURL := call.Arguments[0].String()
+	callbackURL := ""
+	if len(call.Arguments) > 1 && !goja.IsUndefined(call.Arguments[1]) {
+		callbackURL = call.Arguments[1].String()
+	}
+
+	pendingAuthRequestsMu.Lock()
+	pendingAuthRequests[r.extensionID] = &PendingAuthRequest{
+		ExtensionID: r.extensionID,
+		AuthURL:     authURL,
+		CallbackURL: callbackURL,
+	}
+	pendingAuthRequestsMu.Unlock()
+
+	extensionAuthStateMu.Lock()
+	state, exists := extensionAuthState[r.extensionID]
+	if !exists {
+		state = &ExtensionAuthState{}
+		extensionAuthState[r.extensionID] = state
+	}
+	state.PendingAuthURL = authURL
+	state.AuthCode = ""
+	extensionAuthStateMu.Unlock()
+
+	GoLog("[Extension:%s] Auth URL requested: %s\n", r.extensionID, authURL)
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"message": "Auth URL will be opened by the app",
+	})
+}
+
+func (r *ExtensionRuntime) authGetCode(call goja.FunctionCall) goja.Value {
+	extensionAuthStateMu.RLock()
+	defer extensionAuthStateMu.RUnlock()
+
+	state, exists := extensionAuthState[r.extensionID]
+	if !exists || state.AuthCode == "" {
+		return goja.Undefined()
+	}
+
+	return r.vm.ToValue(state.AuthCode)
+}
+
+// authSetCode sets auth code and tokens (can be called by extension after token exchange)
+func (r *ExtensionRuntime) authSetCode(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(false)
+	}
+
+	// Can accept either just auth code or an object with tokens
+	arg := call.Arguments[0].Export()
+
+	extensionAuthStateMu.Lock()
+	defer extensionAuthStateMu.Unlock()
+
+	state, exists := extensionAuthState[r.extensionID]
+	if !exists {
+		state = &ExtensionAuthState{}
+		extensionAuthState[r.extensionID] = state
+	}
+
+	switch v := arg.(type) {
+	case string:
+		state.AuthCode = v
+	case map[string]interface{}:
+		if code, ok := v["code"].(string); ok {
+			state.AuthCode = code
+		}
+		if accessToken, ok := v["access_token"].(string); ok {
+			state.AccessToken = accessToken
+			state.IsAuthenticated = true
+		}
+		if refreshToken, ok := v["refresh_token"].(string); ok {
+			state.RefreshToken = refreshToken
+		}
+		if expiresIn, ok := v["expires_in"].(float64); ok {
+			state.ExpiresAt = time.Now().Add(time.Duration(expiresIn) * time.Second)
+		}
+	}
+
+	return r.vm.ToValue(true)
+}
+
+func (r *ExtensionRuntime) authClear(call goja.FunctionCall) goja.Value {
+	extensionAuthStateMu.Lock()
+	delete(extensionAuthState, r.extensionID)
+	extensionAuthStateMu.Unlock()
+
+	pendingAuthRequestsMu.Lock()
+	delete(pendingAuthRequests, r.extensionID)
+	pendingAuthRequestsMu.Unlock()
+
+	GoLog("[Extension:%s] Auth state cleared\n", r.extensionID)
+	return r.vm.ToValue(true)
+}
+
+// authIsAuthenticated checks if extension has valid auth
+func (r *ExtensionRuntime) authIsAuthenticated(call goja.FunctionCall) goja.Value {
+	extensionAuthStateMu.RLock()
+	defer extensionAuthStateMu.RUnlock()
+
+	state, exists := extensionAuthState[r.extensionID]
+	if !exists {
+		return r.vm.ToValue(false)
+	}
+
+	if state.IsAuthenticated && !state.ExpiresAt.IsZero() && time.Now().After(state.ExpiresAt) {
+		return r.vm.ToValue(false)
+	}
+
+	return r.vm.ToValue(state.IsAuthenticated)
+}
+
+func (r *ExtensionRuntime) authGetTokens(call goja.FunctionCall) goja.Value {
+	extensionAuthStateMu.RLock()
+	defer extensionAuthStateMu.RUnlock()
+
+	state, exists := extensionAuthState[r.extensionID]
+	if !exists {
+		return r.vm.ToValue(map[string]interface{}{})
+	}
+
+	result := map[string]interface{}{
+		"access_token":     state.AccessToken,
+		"refresh_token":    state.RefreshToken,
+		"is_authenticated": state.IsAuthenticated,
+	}
+
+	if !state.ExpiresAt.IsZero() {
+		result["expires_at"] = state.ExpiresAt.Unix()
+		result["is_expired"] = time.Now().After(state.ExpiresAt)
+	}
+
+	return r.vm.ToValue(result)
+}
+
+// ==================== PKCE Support ====================
+
+// generatePKCEVerifier generates a cryptographically random code verifier
+// Length should be between 43-128 characters (RFC 7636)
+func generatePKCEVerifier(length int) (string, error) {
+	if length < 43 {
+		length = 43
+	}
+	if length > 128 {
+		length = 128
+	}
+
+	bytes := make([]byte, length)
+	if _, err := rand.Read(bytes); err != nil {
+		return "", err
+	}
+
+	verifier := base64.RawURLEncoding.EncodeToString(bytes)
+
+	if len(verifier) > length {
+		verifier = verifier[:length]
+	}
+
+	return verifier, nil
+}
+
+func generatePKCEChallenge(verifier string) string {
+	hash := sha256.Sum256([]byte(verifier))
+	// Base64url encode without padding (RFC 7636)
+	return base64.RawURLEncoding.EncodeToString(hash[:])
+}
+
+func (r *ExtensionRuntime) authGeneratePKCE(call goja.FunctionCall) goja.Value {
+	// Default length is 64 characters
+	length := 64
+	if len(call.Arguments) > 0 && !goja.IsUndefined(call.Arguments[0]) {
+		if l, ok := call.Arguments[0].Export().(float64); ok && l >= 43 && l <= 128 {
+			length = int(l)
+		}
+	}
+
+	verifier, err := generatePKCEVerifier(length)
+	if err != nil {
+		GoLog("[Extension:%s] PKCE generation error: %v\n", r.extensionID, err)
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	challenge := generatePKCEChallenge(verifier)
+
+	extensionAuthStateMu.Lock()
+	state, exists := extensionAuthState[r.extensionID]
+	if !exists {
+		state = &ExtensionAuthState{}
+		extensionAuthState[r.extensionID] = state
+	}
+	state.PKCEVerifier = verifier
+	state.PKCEChallenge = challenge
+	extensionAuthStateMu.Unlock()
+
+	GoLog("[Extension:%s] PKCE generated (verifier length: %d)\n", r.extensionID, len(verifier))
+
+	return r.vm.ToValue(map[string]interface{}{
+		"verifier":  verifier,
+		"challenge": challenge,
+		"method":    "S256",
+	})
+}
+
+func (r *ExtensionRuntime) authGetPKCE(call goja.FunctionCall) goja.Value {
+	extensionAuthStateMu.RLock()
+	defer extensionAuthStateMu.RUnlock()
+
+	state, exists := extensionAuthState[r.extensionID]
+	if !exists || state.PKCEVerifier == "" {
+		return r.vm.ToValue(map[string]interface{}{})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"verifier":  state.PKCEVerifier,
+		"challenge": state.PKCEChallenge,
+		"method":    "S256",
+	})
+}
+
+// authStartOAuthWithPKCE is a high-level helper that generates PKCE and opens OAuth URL
+// config: { authUrl, clientId, redirectUri, scope, extraParams }
+// Returns: { success, authUrl, pkce: { verifier, challenge } }
+func (r *ExtensionRuntime) authStartOAuthWithPKCE(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "config object is required",
+		})
+	}
+
+	configObj := call.Arguments[0].Export()
+	config, ok := configObj.(map[string]interface{})
+	if !ok {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "config must be an object",
+		})
+	}
+
+	// Required fields
+	authURL, _ := config["authUrl"].(string)
+	clientID, _ := config["clientId"].(string)
+	redirectURI, _ := config["redirectUri"].(string)
+
+	if authURL == "" || clientID == "" || redirectURI == "" {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "authUrl, clientId, and redirectUri are required",
+		})
+	}
+
+	// Optional fields
+	scope, _ := config["scope"].(string)
+	extraParams, _ := config["extraParams"].(map[string]interface{})
+
+	// Generate PKCE
+	verifier, err := generatePKCEVerifier(64)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to generate PKCE: %v", err),
+		})
+	}
+	challenge := generatePKCEChallenge(verifier)
+
+	// Store PKCE in auth state
+	extensionAuthStateMu.Lock()
+	state, exists := extensionAuthState[r.extensionID]
+	if !exists {
+		state = &ExtensionAuthState{}
+		extensionAuthState[r.extensionID] = state
+	}
+	state.PKCEVerifier = verifier
+	state.PKCEChallenge = challenge
+	state.AuthCode = "" // Clear any previous auth code
+	extensionAuthStateMu.Unlock()
+
+	// Build OAuth URL with PKCE parameters
+	parsedURL, err := url.Parse(authURL)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("invalid authUrl: %v", err),
+		})
+	}
+
+	query := parsedURL.Query()
+	query.Set("client_id", clientID)
+	query.Set("redirect_uri", redirectURI)
+	query.Set("response_type", "code")
+	query.Set("code_challenge", challenge)
+	query.Set("code_challenge_method", "S256")
+
+	if scope != "" {
+		query.Set("scope", scope)
+	}
+
+	// Add extra params
+	for k, v := range extraParams {
+		query.Set(k, fmt.Sprintf("%v", v))
+	}
+
+	parsedURL.RawQuery = query.Encode()
+	fullAuthURL := parsedURL.String()
+
+	// Store pending auth request for Flutter
+	pendingAuthRequestsMu.Lock()
+	pendingAuthRequests[r.extensionID] = &PendingAuthRequest{
+		ExtensionID: r.extensionID,
+		AuthURL:     fullAuthURL,
+		CallbackURL: redirectURI,
+	}
+	pendingAuthRequestsMu.Unlock()
+
+	GoLog("[Extension:%s] PKCE OAuth started: %s\n", r.extensionID, fullAuthURL)
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"authUrl": fullAuthURL,
+		"pkce": map[string]interface{}{
+			"verifier":  verifier,
+			"challenge": challenge,
+			"method":    "S256",
+		},
+	})
+}
+
+// authExchangeCodeWithPKCE exchanges auth code for tokens using PKCE
+// config: { tokenUrl, clientId, redirectUri, code, extraParams }
+// Uses the stored PKCE verifier automatically
+func (r *ExtensionRuntime) authExchangeCodeWithPKCE(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "config object is required",
+		})
+	}
+
+	configObj := call.Arguments[0].Export()
+	config, ok := configObj.(map[string]interface{})
+	if !ok {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "config must be an object",
+		})
+	}
+
+	// Required fields
+	tokenURL, _ := config["tokenUrl"].(string)
+	clientID, _ := config["clientId"].(string)
+	redirectURI, _ := config["redirectUri"].(string)
+	code, _ := config["code"].(string)
+
+	if tokenURL == "" || clientID == "" || code == "" {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "tokenUrl, clientId, and code are required",
+		})
+	}
+
+	extensionAuthStateMu.RLock()
+	state, exists := extensionAuthState[r.extensionID]
+	var verifier string
+	if exists {
+		verifier = state.PKCEVerifier
+	}
+	extensionAuthStateMu.RUnlock()
+
+	if verifier == "" {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "no PKCE verifier found - call generatePKCE or startOAuthWithPKCE first",
+		})
+	}
+
+	if err := r.validateDomain(tokenURL); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	formData := url.Values{}
+	formData.Set("grant_type", "authorization_code")
+	formData.Set("client_id", clientID)
+	formData.Set("code", code)
+	formData.Set("code_verifier", verifier)
+	if redirectURI != "" {
+		formData.Set("redirect_uri", redirectURI)
+	}
+
+	if extraParams, ok := config["extraParams"].(map[string]interface{}); ok {
+		for k, v := range extraParams {
+			formData.Set(k, fmt.Sprintf("%v", v))
+		}
+	}
+
+	req, err := http.NewRequest("POST", tokenURL, strings.NewReader(formData.Encode()))
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.Header.Set("User-Agent", "SpotiFLAC-Extension/1.0")
+
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	var tokenResp map[string]interface{}
+	if err := json.Unmarshal(body, &tokenResp); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to parse token response: %v", err),
+			"body":    string(body),
+		})
+	}
+
+	if errMsg, ok := tokenResp["error"].(string); ok {
+		errDesc, _ := tokenResp["error_description"].(string)
+		return r.vm.ToValue(map[string]interface{}{
+			"success":           false,
+			"error":             errMsg,
+			"error_description": errDesc,
+		})
+	}
+
+	accessToken, _ := tokenResp["access_token"].(string)
+	refreshToken, _ := tokenResp["refresh_token"].(string)
+	expiresIn, _ := tokenResp["expires_in"].(float64)
+
+	if accessToken == "" {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "no access_token in response",
+			"body":    string(body),
+		})
+	}
+
+	extensionAuthStateMu.Lock()
+	state, exists = extensionAuthState[r.extensionID]
+	if !exists {
+		state = &ExtensionAuthState{}
+		extensionAuthState[r.extensionID] = state
+	}
+	state.AccessToken = accessToken
+	state.RefreshToken = refreshToken
+	state.IsAuthenticated = true
+	if expiresIn > 0 {
+		state.ExpiresAt = time.Now().Add(time.Duration(expiresIn) * time.Second)
+	}
+	state.PKCEVerifier = ""
+	state.PKCEChallenge = ""
+	extensionAuthStateMu.Unlock()
+
+	GoLog("[Extension:%s] PKCE token exchange successful\n", r.extensionID)
+
+	result := map[string]interface{}{
+		"success":       true,
+		"access_token":  accessToken,
+		"refresh_token": refreshToken,
+		"token_type":    tokenResp["token_type"],
+	}
+	if expiresIn > 0 {
+		result["expires_in"] = expiresIn
+	}
+	if scope, ok := tokenResp["scope"].(string); ok {
+		result["scope"] = scope
+	}
+
+	return r.vm.ToValue(result)
+}

go_backend/extension_runtime_ffmpeg.go

@@ -0,0 +1,198 @@
+// Package gobackend provides FFmpeg API for extension runtime
+package gobackend
+
+import (
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/dop251/goja"
+)
+
+// ==================== FFmpeg API (Post-Processing) ====================
+
+// FFmpegCommand holds a pending FFmpeg command for Flutter to execute
+type FFmpegCommand struct {
+	ExtensionID string
+	Command     string
+	InputPath   string
+	OutputPath  string
+	Completed   bool
+	Success     bool
+	Error       string
+	Output      string
+}
+
+// Global FFmpeg command queue
+var (
+	ffmpegCommands   = make(map[string]*FFmpegCommand)
+	ffmpegCommandsMu sync.RWMutex
+	ffmpegCommandID  int64
+)
+
+func GetPendingFFmpegCommand(commandID string) *FFmpegCommand {
+	ffmpegCommandsMu.RLock()
+	defer ffmpegCommandsMu.RUnlock()
+	return ffmpegCommands[commandID]
+}
+
+func SetFFmpegCommandResult(commandID string, success bool, output, errorMsg string) {
+	ffmpegCommandsMu.Lock()
+	defer ffmpegCommandsMu.Unlock()
+	if cmd, exists := ffmpegCommands[commandID]; exists {
+		cmd.Completed = true
+		cmd.Success = success
+		cmd.Output = output
+		cmd.Error = errorMsg
+	}
+}
+
+func ClearFFmpegCommand(commandID string) {
+	ffmpegCommandsMu.Lock()
+	defer ffmpegCommandsMu.Unlock()
+	delete(ffmpegCommands, commandID)
+}
+
+func (r *ExtensionRuntime) ffmpegExecute(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "command is required",
+		})
+	}
+
+	command := call.Arguments[0].String()
+
+	// Generate unique command ID
+	ffmpegCommandsMu.Lock()
+	ffmpegCommandID++
+	cmdID := fmt.Sprintf("%s_%d", r.extensionID, ffmpegCommandID)
+	ffmpegCommands[cmdID] = &FFmpegCommand{
+		ExtensionID: r.extensionID,
+		Command:     command,
+		Completed:   false,
+	}
+	ffmpegCommandsMu.Unlock()
+
+	GoLog("[Extension:%s] FFmpeg command queued: %s\n", r.extensionID, cmdID)
+
+	// Wait for completion (with timeout)
+	timeout := 5 * time.Minute
+	start := time.Now()
+	for {
+		ffmpegCommandsMu.RLock()
+		cmd := ffmpegCommands[cmdID]
+		completed := cmd != nil && cmd.Completed
+		ffmpegCommandsMu.RUnlock()
+
+		if completed {
+			ffmpegCommandsMu.RLock()
+			result := map[string]interface{}{
+				"success": cmd.Success,
+				"output":  cmd.Output,
+			}
+			if cmd.Error != "" {
+				result["error"] = cmd.Error
+			}
+			ffmpegCommandsMu.RUnlock()
+
+			// Cleanup
+			ClearFFmpegCommand(cmdID)
+			return r.vm.ToValue(result)
+		}
+
+		if time.Since(start) > timeout {
+			ClearFFmpegCommand(cmdID)
+			return r.vm.ToValue(map[string]interface{}{
+				"success": false,
+				"error":   "FFmpeg command timed out",
+			})
+		}
+
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+func (r *ExtensionRuntime) ffmpegGetInfo(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "file path is required",
+		})
+	}
+
+	filePath := call.Arguments[0].String()
+
+	// Use Go's built-in audio quality function
+	quality, err := GetAudioQuality(filePath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success":       true,
+		"bit_depth":     quality.BitDepth,
+		"sample_rate":   quality.SampleRate,
+		"total_samples": quality.TotalSamples,
+		"duration":      float64(quality.TotalSamples) / float64(quality.SampleRate),
+	})
+}
+
+func (r *ExtensionRuntime) ffmpegConvert(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "input and output paths are required",
+		})
+	}
+
+	inputPath := call.Arguments[0].String()
+	outputPath := call.Arguments[1].String()
+
+	// Get options if provided
+	options := map[string]interface{}{}
+	if len(call.Arguments) > 2 && !goja.IsUndefined(call.Arguments[2]) && !goja.IsNull(call.Arguments[2]) {
+		if opts, ok := call.Arguments[2].Export().(map[string]interface{}); ok {
+			options = opts
+		}
+	}
+
+	// Build FFmpeg command
+	var cmdParts []string
+	cmdParts = append(cmdParts, "-i", fmt.Sprintf("%q", inputPath))
+
+	// Audio codec
+	if codec, ok := options["codec"].(string); ok {
+		cmdParts = append(cmdParts, "-c:a", codec)
+	}
+
+	// Bitrate
+	if bitrate, ok := options["bitrate"].(string); ok {
+		cmdParts = append(cmdParts, "-b:a", bitrate)
+	}
+
+	// Sample rate
+	if sampleRate, ok := options["sample_rate"].(float64); ok {
+		cmdParts = append(cmdParts, "-ar", fmt.Sprintf("%d", int(sampleRate)))
+	}
+
+	// Channels
+	if channels, ok := options["channels"].(float64); ok {
+		cmdParts = append(cmdParts, "-ac", fmt.Sprintf("%d", int(channels)))
+	}
+
+	// Overwrite output
+	cmdParts = append(cmdParts, "-y", fmt.Sprintf("%q", outputPath))
+
+	command := strings.Join(cmdParts, " ")
+
+	// Execute via ffmpegExecute
+	execCall := goja.FunctionCall{
+		Arguments: []goja.Value{r.vm.ToValue(command)},
+	}
+	return r.ffmpegExecute(execCall)
+}

go_backend/extension_runtime_file.go

@@ -0,0 +1,485 @@
+// Package gobackend provides File API for extension runtime
+package gobackend
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+
+	"github.com/dop251/goja"
+)
+
+// ==================== File API (Sandboxed) ====================
+
+// List of allowed directories for file operations (set by Go backend for download operations)
+var (
+	allowedDownloadDirs   []string
+	allowedDownloadDirsMu sync.RWMutex
+)
+
+func SetAllowedDownloadDirs(dirs []string) {
+	allowedDownloadDirsMu.Lock()
+	defer allowedDownloadDirsMu.Unlock()
+	allowedDownloadDirs = dirs
+	GoLog("[Extension] Allowed download directories set: %v\n", dirs)
+}
+
+func AddAllowedDownloadDir(dir string) {
+	allowedDownloadDirsMu.Lock()
+	defer allowedDownloadDirsMu.Unlock()
+	absDir, err := filepath.Abs(dir)
+	if err == nil {
+		allowedDownloadDirs = append(allowedDownloadDirs, absDir)
+	}
+}
+
+func isPathInAllowedDirs(absPath string) bool {
+	allowedDownloadDirsMu.RLock()
+	defer allowedDownloadDirsMu.RUnlock()
+
+	for _, allowedDir := range allowedDownloadDirs {
+		if strings.HasPrefix(absPath, allowedDir) {
+			return true
+		}
+	}
+	return false
+}
+
+// validatePath checks if the path is within the extension's sandbox
+// Security: Absolute paths are BLOCKED unless they're in allowed download directories
+// Extensions should use relative paths for their own data storage
+func (r *ExtensionRuntime) validatePath(path string) (string, error) {
+	// Check if extension has file permission
+	if !r.manifest.Permissions.File {
+		return "", fmt.Errorf("file access denied: extension does not have 'file' permission")
+	}
+
+	cleanPath := filepath.Clean(path)
+
+	if filepath.IsAbs(cleanPath) {
+		absPath, err := filepath.Abs(cleanPath)
+		if err != nil {
+			return "", fmt.Errorf("invalid path: %w", err)
+		}
+
+		if isPathInAllowedDirs(absPath) {
+			return absPath, nil
+		}
+
+		return "", fmt.Errorf("file access denied: absolute paths are not allowed. Use relative paths within extension sandbox")
+	}
+
+	fullPath := filepath.Join(r.dataDir, cleanPath)
+
+	absPath, err := filepath.Abs(fullPath)
+	if err != nil {
+		return "", fmt.Errorf("invalid path: %w", err)
+	}
+
+	absDataDir, _ := filepath.Abs(r.dataDir)
+	if !strings.HasPrefix(absPath, absDataDir) {
+		return "", fmt.Errorf("file access denied: path '%s' is outside sandbox", path)
+	}
+
+	return absPath, nil
+}
+
+func (r *ExtensionRuntime) fileDownload(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "URL and output path are required",
+		})
+	}
+
+	urlStr := call.Arguments[0].String()
+	outputPath := call.Arguments[1].String()
+
+	if err := r.validateDomain(urlStr); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	fullPath, err := r.validatePath(outputPath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	var onProgress goja.Callable
+	var headers map[string]string
+	if len(call.Arguments) > 2 && !goja.IsUndefined(call.Arguments[2]) && !goja.IsNull(call.Arguments[2]) {
+		optionsObj := call.Arguments[2].Export()
+		if opts, ok := optionsObj.(map[string]interface{}); ok {
+			if h, ok := opts["headers"].(map[string]interface{}); ok {
+				headers = make(map[string]string)
+				for k, v := range h {
+					headers[k] = fmt.Sprintf("%v", v)
+				}
+			}
+			if progressVal, ok := opts["onProgress"]; ok {
+				if callable, ok := goja.AssertFunction(r.vm.ToValue(progressVal)); ok {
+					onProgress = callable
+				}
+			}
+		}
+	}
+
+	dir := filepath.Dir(fullPath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to create directory: %v", err),
+		})
+	}
+
+	req, err := http.NewRequest("GET", urlStr, nil)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	for k, v := range headers {
+		req.Header.Set(k, v)
+	}
+	if req.Header.Get("User-Agent") == "" {
+		req.Header.Set("User-Agent", "SpotiFLAC-Extension/1.0")
+	}
+
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("HTTP error: %d", resp.StatusCode),
+		})
+	}
+
+	out, err := os.Create(fullPath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to create file: %v", err),
+		})
+	}
+	defer out.Close()
+
+	contentLength := resp.ContentLength
+
+	var written int64
+	buf := make([]byte, 32*1024)
+	for {
+		nr, er := resp.Body.Read(buf)
+		if nr > 0 {
+			nw, ew := out.Write(buf[0:nr])
+			if nw < 0 || nr < nw {
+				nw = 0
+				if ew == nil {
+					ew = fmt.Errorf("invalid write result")
+				}
+			}
+			written += int64(nw)
+			if ew != nil {
+				return r.vm.ToValue(map[string]interface{}{
+					"success": false,
+					"error":   fmt.Sprintf("failed to write file: %v", ew),
+				})
+			}
+			if nr != nw {
+				return r.vm.ToValue(map[string]interface{}{
+					"success": false,
+					"error":   "short write",
+				})
+			}
+
+			if onProgress != nil && contentLength > 0 {
+				_, _ = onProgress(goja.Undefined(), r.vm.ToValue(written), r.vm.ToValue(contentLength))
+			}
+		}
+		if er != nil {
+			if er != io.EOF {
+				return r.vm.ToValue(map[string]interface{}{
+					"success": false,
+					"error":   fmt.Sprintf("failed to read response: %v", er),
+				})
+			}
+			break
+		}
+	}
+
+	GoLog("[Extension:%s] Downloaded %d bytes to %s\n", r.extensionID, written, fullPath)
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"path":    fullPath,
+		"size":    written,
+	})
+}
+
+func (r *ExtensionRuntime) fileExists(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(false)
+	}
+
+	path := call.Arguments[0].String()
+	fullPath, err := r.validatePath(path)
+	if err != nil {
+		return r.vm.ToValue(false)
+	}
+
+	_, err = os.Stat(fullPath)
+	return r.vm.ToValue(err == nil)
+}
+
+func (r *ExtensionRuntime) fileDelete(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "path is required",
+		})
+	}
+
+	path := call.Arguments[0].String()
+	fullPath, err := r.validatePath(path)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	if err := os.Remove(fullPath); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+	})
+}
+
+func (r *ExtensionRuntime) fileRead(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "path is required",
+		})
+	}
+
+	path := call.Arguments[0].String()
+	fullPath, err := r.validatePath(path)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	data, err := os.ReadFile(fullPath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"data":    string(data),
+	})
+}
+
+func (r *ExtensionRuntime) fileWrite(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "path and data are required",
+		})
+	}
+
+	path := call.Arguments[0].String()
+	data := call.Arguments[1].String()
+
+	fullPath, err := r.validatePath(path)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	// Create directory if needed
+	dir := filepath.Dir(fullPath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to create directory: %v", err),
+		})
+	}
+
+	if err := os.WriteFile(fullPath, []byte(data), 0644); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"path":    fullPath,
+	})
+}
+
+func (r *ExtensionRuntime) fileCopy(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "source and destination paths are required",
+		})
+	}
+
+	srcPath := call.Arguments[0].String()
+	dstPath := call.Arguments[1].String()
+
+	fullSrc, err := r.validatePath(srcPath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	fullDst, err := r.validatePath(dstPath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	data, err := os.ReadFile(fullSrc)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to read source: %v", err),
+		})
+	}
+
+	dir := filepath.Dir(fullDst)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to create directory: %v", err),
+		})
+	}
+
+	if err := os.WriteFile(fullDst, data, 0644); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to write destination: %v", err),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"path":    fullDst,
+	})
+}
+
+func (r *ExtensionRuntime) fileMove(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "source and destination paths are required",
+		})
+	}
+
+	srcPath := call.Arguments[0].String()
+	dstPath := call.Arguments[1].String()
+
+	fullSrc, err := r.validatePath(srcPath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	fullDst, err := r.validatePath(dstPath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	dir := filepath.Dir(fullDst)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to create directory: %v", err),
+		})
+	}
+
+	if err := os.Rename(fullSrc, fullDst); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   fmt.Sprintf("failed to move file: %v", err),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"path":    fullDst,
+	})
+}
+
+func (r *ExtensionRuntime) fileGetSize(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "path is required",
+		})
+	}
+
+	path := call.Arguments[0].String()
+	fullPath, err := r.validatePath(path)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	info, err := os.Stat(fullPath)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"size":    info.Size(),
+	})
+}

go_backend/extension_runtime_http.go

@@ -0,0 +1,489 @@
+// Package gobackend provides HTTP API for extension runtime
+package gobackend
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/dop251/goja"
+)
+
+// ==================== HTTP API (Sandboxed) ====================
+
+// HTTPResponse represents the response from an HTTP request
+type HTTPResponse struct {
+	StatusCode int               `json:"statusCode"`
+	Body       string            `json:"body"`
+	Headers    map[string]string `json:"headers"`
+}
+
+// validateDomain checks if the domain is allowed by the extension's permissions
+func (r *ExtensionRuntime) validateDomain(urlStr string) error {
+	parsed, err := url.Parse(urlStr)
+	if err != nil {
+		return fmt.Errorf("invalid URL: %w", err)
+	}
+
+	domain := parsed.Hostname()
+
+	// Block private/local network access (SSRF protection)
+	if isPrivateIP(domain) {
+		return fmt.Errorf("network access denied: private/local network '%s' not allowed", domain)
+	}
+
+	if !r.manifest.IsDomainAllowed(domain) {
+		return fmt.Errorf("network access denied: domain '%s' not in allowed list", domain)
+	}
+
+	return nil
+}
+
+// httpGet performs a GET request (sandboxed)
+func (r *ExtensionRuntime) httpGet(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": "URL is required",
+		})
+	}
+
+	urlStr := call.Arguments[0].String()
+
+	if err := r.validateDomain(urlStr); err != nil {
+		GoLog("[Extension:%s] HTTP blocked: %v\n", r.extensionID, err)
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	headers := make(map[string]string)
+	if len(call.Arguments) > 1 && !goja.IsUndefined(call.Arguments[1]) && !goja.IsNull(call.Arguments[1]) {
+		headersObj := call.Arguments[1].Export()
+		if h, ok := headersObj.(map[string]interface{}); ok {
+			for k, v := range h {
+				headers[k] = fmt.Sprintf("%v", v)
+			}
+		}
+	}
+
+	req, err := http.NewRequest("GET", urlStr, nil)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Set headers - user headers first
+	for k, v := range headers {
+		req.Header.Set(k, v)
+	}
+	// Only set default User-Agent if not provided by extension
+	if req.Header.Get("User-Agent") == "" {
+		req.Header.Set("User-Agent", "Spotiflac-Extension/1.0")
+	}
+
+	// Execute request
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Extract response headers - return all values as arrays for multi-value headers (cookies, etc.)
+	respHeaders := make(map[string]interface{})
+	for k, v := range resp.Header {
+		if len(v) == 1 {
+			respHeaders[k] = v[0]
+		} else {
+			respHeaders[k] = v // Return as array if multiple values
+		}
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"statusCode": resp.StatusCode,
+		"status":     resp.StatusCode, // Alias for convenience
+		"ok":         resp.StatusCode >= 200 && resp.StatusCode < 300,
+		"body":       string(body),
+		"headers":    respHeaders,
+	})
+}
+
+// httpPost performs a POST request (sandboxed)
+func (r *ExtensionRuntime) httpPost(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": "URL is required",
+		})
+	}
+
+	urlStr := call.Arguments[0].String()
+
+	if err := r.validateDomain(urlStr); err != nil {
+		GoLog("[Extension:%s] HTTP blocked: %v\n", r.extensionID, err)
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Get body if provided - support both string and object
+	var bodyStr string
+	if len(call.Arguments) > 1 && !goja.IsUndefined(call.Arguments[1]) && !goja.IsNull(call.Arguments[1]) {
+		bodyArg := call.Arguments[1].Export()
+		switch v := bodyArg.(type) {
+		case string:
+			bodyStr = v
+		case map[string]interface{}, []interface{}:
+			// Auto-stringify objects and arrays to JSON
+			jsonBytes, err := json.Marshal(v)
+			if err != nil {
+				return r.vm.ToValue(map[string]interface{}{
+					"error": fmt.Sprintf("failed to stringify body: %v", err),
+				})
+			}
+			bodyStr = string(jsonBytes)
+		default:
+			// Fallback to string conversion
+			bodyStr = call.Arguments[1].String()
+		}
+	}
+
+	// Get headers if provided
+	headers := make(map[string]string)
+	if len(call.Arguments) > 2 && !goja.IsUndefined(call.Arguments[2]) && !goja.IsNull(call.Arguments[2]) {
+		headersObj := call.Arguments[2].Export()
+		if h, ok := headersObj.(map[string]interface{}); ok {
+			for k, v := range h {
+				headers[k] = fmt.Sprintf("%v", v)
+			}
+		}
+	}
+
+	req, err := http.NewRequest("POST", urlStr, strings.NewReader(bodyStr))
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Set headers - user headers first
+	for k, v := range headers {
+		req.Header.Set(k, v)
+	}
+	// Only set defaults if not provided by extension
+	if req.Header.Get("User-Agent") == "" {
+		req.Header.Set("User-Agent", "Spotiflac-Extension/1.0")
+	}
+	if req.Header.Get("Content-Type") == "" {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
+	// Execute request
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Extract response headers - return all values as arrays for multi-value headers
+	respHeaders := make(map[string]interface{})
+	for k, v := range resp.Header {
+		if len(v) == 1 {
+			respHeaders[k] = v[0]
+		} else {
+			respHeaders[k] = v // Return as array if multiple values
+		}
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"statusCode": resp.StatusCode,
+		"status":     resp.StatusCode, // Alias for convenience
+		"ok":         resp.StatusCode >= 200 && resp.StatusCode < 300,
+		"body":       string(body),
+		"headers":    respHeaders,
+	})
+}
+
+func (r *ExtensionRuntime) httpRequest(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": "URL is required",
+		})
+	}
+
+	urlStr := call.Arguments[0].String()
+
+	if err := r.validateDomain(urlStr); err != nil {
+		GoLog("[Extension:%s] HTTP blocked: %v\n", r.extensionID, err)
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Default options
+	method := "GET"
+	var bodyStr string
+	headers := make(map[string]string)
+
+	// Parse options if provided
+	if len(call.Arguments) > 1 && !goja.IsUndefined(call.Arguments[1]) && !goja.IsNull(call.Arguments[1]) {
+		optionsObj := call.Arguments[1].Export()
+		if opts, ok := optionsObj.(map[string]interface{}); ok {
+			// Get method
+			if m, ok := opts["method"].(string); ok {
+				method = strings.ToUpper(m)
+			}
+
+			// Get body - support both string and object
+			if bodyArg, ok := opts["body"]; ok && bodyArg != nil {
+				switch v := bodyArg.(type) {
+				case string:
+					bodyStr = v
+				case map[string]interface{}, []interface{}:
+					// Auto-stringify objects and arrays to JSON
+					jsonBytes, err := json.Marshal(v)
+					if err != nil {
+						return r.vm.ToValue(map[string]interface{}{
+							"error": fmt.Sprintf("failed to stringify body: %v", err),
+						})
+					}
+					bodyStr = string(jsonBytes)
+				default:
+					bodyStr = fmt.Sprintf("%v", v)
+				}
+			}
+
+			// Get headers
+			if h, ok := opts["headers"].(map[string]interface{}); ok {
+				for k, v := range h {
+					headers[k] = fmt.Sprintf("%v", v)
+				}
+			}
+		}
+	}
+
+	// Create request
+	var reqBody io.Reader
+	if bodyStr != "" {
+		reqBody = strings.NewReader(bodyStr)
+	}
+
+	req, err := http.NewRequest(method, urlStr, reqBody)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Set headers - user headers first
+	for k, v := range headers {
+		req.Header.Set(k, v)
+	}
+	// Only set defaults if not provided by extension
+	if req.Header.Get("User-Agent") == "" {
+		req.Header.Set("User-Agent", "Spotiflac-Extension/1.0")
+	}
+	if bodyStr != "" && req.Header.Get("Content-Type") == "" {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
+	// Execute request
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Extract response headers - return all values as arrays for multi-value headers
+	respHeaders := make(map[string]interface{})
+	for k, v := range resp.Header {
+		if len(v) == 1 {
+			respHeaders[k] = v[0]
+		} else {
+			respHeaders[k] = v // Return as array if multiple values
+		}
+	}
+
+	// Return response with helper properties
+	return r.vm.ToValue(map[string]interface{}{
+		"statusCode": resp.StatusCode,
+		"status":     resp.StatusCode, // Alias for convenience
+		"ok":         resp.StatusCode >= 200 && resp.StatusCode < 300,
+		"body":       string(body),
+		"headers":    respHeaders,
+	})
+}
+
+func (r *ExtensionRuntime) httpPut(call goja.FunctionCall) goja.Value {
+	return r.httpMethodShortcut("PUT", call)
+}
+
+// httpDelete performs a DELETE request (shortcut for http.request with method: "DELETE")
+func (r *ExtensionRuntime) httpDelete(call goja.FunctionCall) goja.Value {
+	return r.httpMethodShortcut("DELETE", call)
+}
+
+func (r *ExtensionRuntime) httpPatch(call goja.FunctionCall) goja.Value {
+	return r.httpMethodShortcut("PATCH", call)
+}
+
+// httpMethodShortcut is a helper for PUT/DELETE/PATCH shortcuts
+// Signature: http.put(url, body, headers) / http.delete(url, headers) / http.patch(url, body, headers)
+func (r *ExtensionRuntime) httpMethodShortcut(method string, call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": "URL is required",
+		})
+	}
+
+	urlStr := call.Arguments[0].String()
+
+	if err := r.validateDomain(urlStr); err != nil {
+		GoLog("[Extension:%s] HTTP blocked: %v\n", r.extensionID, err)
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	var bodyStr string
+	headers := make(map[string]string)
+
+	// For DELETE, second arg is headers; for PUT/PATCH, second arg is body
+	if method == "DELETE" {
+		// http.delete(url, headers)
+		if len(call.Arguments) > 1 && !goja.IsUndefined(call.Arguments[1]) && !goja.IsNull(call.Arguments[1]) {
+			headersObj := call.Arguments[1].Export()
+			if h, ok := headersObj.(map[string]interface{}); ok {
+				for k, v := range h {
+					headers[k] = fmt.Sprintf("%v", v)
+				}
+			}
+		}
+	} else {
+		// http.put(url, body, headers) / http.patch(url, body, headers)
+		if len(call.Arguments) > 1 && !goja.IsUndefined(call.Arguments[1]) && !goja.IsNull(call.Arguments[1]) {
+			bodyArg := call.Arguments[1].Export()
+			switch v := bodyArg.(type) {
+			case string:
+				bodyStr = v
+			case map[string]interface{}, []interface{}:
+				jsonBytes, err := json.Marshal(v)
+				if err != nil {
+					return r.vm.ToValue(map[string]interface{}{
+						"error": fmt.Sprintf("failed to stringify body: %v", err),
+					})
+				}
+				bodyStr = string(jsonBytes)
+			default:
+				bodyStr = call.Arguments[1].String()
+			}
+		}
+
+		if len(call.Arguments) > 2 && !goja.IsUndefined(call.Arguments[2]) && !goja.IsNull(call.Arguments[2]) {
+			headersObj := call.Arguments[2].Export()
+			if h, ok := headersObj.(map[string]interface{}); ok {
+				for k, v := range h {
+					headers[k] = fmt.Sprintf("%v", v)
+				}
+			}
+		}
+	}
+
+	// Create request
+	var reqBody io.Reader
+	if bodyStr != "" {
+		reqBody = strings.NewReader(bodyStr)
+	}
+
+	req, err := http.NewRequest(method, urlStr, reqBody)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Set headers - user headers first
+	for k, v := range headers {
+		req.Header.Set(k, v)
+	}
+	if req.Header.Get("User-Agent") == "" {
+		req.Header.Set("User-Agent", "Spotiflac-Extension/1.0")
+	}
+	if bodyStr != "" && req.Header.Get("Content-Type") == "" {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
+	// Execute request
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"error": err.Error(),
+		})
+	}
+
+	// Extract response headers
+	respHeaders := make(map[string]interface{})
+	for k, v := range resp.Header {
+		if len(v) == 1 {
+			respHeaders[k] = v[0]
+		} else {
+			respHeaders[k] = v
+		}
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"statusCode": resp.StatusCode,
+		"status":     resp.StatusCode,
+		"ok":         resp.StatusCode >= 200 && resp.StatusCode < 300,
+		"body":       string(body),
+		"headers":    respHeaders,
+	})
+}
+
+func (r *ExtensionRuntime) httpClearCookies(call goja.FunctionCall) goja.Value {
+	if jar, ok := r.cookieJar.(*simpleCookieJar); ok {
+		jar.mu.Lock()
+		jar.cookies = make(map[string][]*http.Cookie)
+		jar.mu.Unlock()
+		GoLog("[Extension:%s] Cookies cleared\n", r.extensionID)
+		return r.vm.ToValue(true)
+	}
+	return r.vm.ToValue(false)
+}

go_backend/extension_runtime_matching.go

@@ -0,0 +1,151 @@
+// Package gobackend provides Track Matching API for extension runtime
+package gobackend
+
+import (
+	"strings"
+
+	"github.com/dop251/goja"
+)
+
+// ==================== Track Matching API ====================
+
+// matchingCompareStrings compares two strings with fuzzy matching
+func (r *ExtensionRuntime) matchingCompareStrings(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(0.0)
+	}
+
+	str1 := strings.ToLower(strings.TrimSpace(call.Arguments[0].String()))
+	str2 := strings.ToLower(strings.TrimSpace(call.Arguments[1].String()))
+
+	if str1 == str2 {
+		return r.vm.ToValue(1.0)
+	}
+
+	// Calculate Levenshtein distance-based similarity
+	similarity := calculateStringSimilarity(str1, str2)
+	return r.vm.ToValue(similarity)
+}
+
+// matchingCompareDuration compares two durations with tolerance
+func (r *ExtensionRuntime) matchingCompareDuration(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(false)
+	}
+
+	dur1 := int(call.Arguments[0].ToInteger())
+	dur2 := int(call.Arguments[1].ToInteger())
+
+	// Default tolerance: 3 seconds
+	tolerance := 3000 // milliseconds
+	if len(call.Arguments) > 2 && !goja.IsUndefined(call.Arguments[2]) {
+		tolerance = int(call.Arguments[2].ToInteger())
+	}
+
+	diff := dur1 - dur2
+	if diff < 0 {
+		diff = -diff
+	}
+
+	return r.vm.ToValue(diff <= tolerance)
+}
+
+// matchingNormalizeString normalizes a string for comparison
+func (r *ExtensionRuntime) matchingNormalizeString(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue("")
+	}
+
+	str := call.Arguments[0].String()
+	normalized := normalizeStringForMatching(str)
+	return r.vm.ToValue(normalized)
+}
+
+// calculateStringSimilarity calculates similarity between two strings (0-1)
+func calculateStringSimilarity(s1, s2 string) float64 {
+	if len(s1) == 0 && len(s2) == 0 {
+		return 1.0
+	}
+	if len(s1) == 0 || len(s2) == 0 {
+		return 0.0
+	}
+
+	// Use Levenshtein distance
+	distance := levenshteinDistance(s1, s2)
+	maxLen := len(s1)
+	if len(s2) > maxLen {
+		maxLen = len(s2)
+	}
+
+	return 1.0 - float64(distance)/float64(maxLen)
+}
+
+// levenshteinDistance calculates the Levenshtein distance between two strings
+func levenshteinDistance(s1, s2 string) int {
+	if len(s1) == 0 {
+		return len(s2)
+	}
+	if len(s2) == 0 {
+		return len(s1)
+	}
+
+	// Create matrix
+	matrix := make([][]int, len(s1)+1)
+	for i := range matrix {
+		matrix[i] = make([]int, len(s2)+1)
+		matrix[i][0] = i
+	}
+	for j := range matrix[0] {
+		matrix[0][j] = j
+	}
+
+	// Fill matrix
+	for i := 1; i <= len(s1); i++ {
+		for j := 1; j <= len(s2); j++ {
+			cost := 1
+			if s1[i-1] == s2[j-1] {
+				cost = 0
+			}
+			matrix[i][j] = min(
+				matrix[i-1][j]+1,      // deletion
+				matrix[i][j-1]+1,      // insertion
+				matrix[i-1][j-1]+cost, // substitution
+			)
+		}
+	}
+
+	return matrix[len(s1)][len(s2)]
+}
+
+// normalizeStringForMatching normalizes a string for comparison
+func normalizeStringForMatching(s string) string {
+	// Convert to lowercase
+	s = strings.ToLower(s)
+
+	// Remove common suffixes/prefixes
+	suffixes := []string{
+		" (remastered)", " (remaster)", " - remastered", " - remaster",
+		" (deluxe)", " (deluxe edition)", " - deluxe", " - deluxe edition",
+		" (explicit)", " (clean)", " [explicit]", " [clean]",
+		" (album version)", " (single version)", " (radio edit)",
+		" (feat.", " (ft.", " feat.", " ft.",
+	}
+	for _, suffix := range suffixes {
+		if idx := strings.Index(s, suffix); idx != -1 {
+			s = s[:idx]
+		}
+	}
+
+	// Remove special characters
+	var result strings.Builder
+	for _, r := range s {
+		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == ' ' {
+			result.WriteRune(r)
+		}
+	}
+
+	// Collapse multiple spaces
+	s = strings.Join(strings.Fields(result.String()), " ")
+
+	return strings.TrimSpace(s)
+}

go_backend/extension_runtime_polyfills.go

@@ -0,0 +1,488 @@
+// Package gobackend provides Browser-like Polyfills for extension runtime
+package gobackend
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/dop251/goja"
+)
+
+// ==================== Browser-like Polyfills ====================
+// These polyfills make porting browser/Node.js libraries easier
+// without compromising sandbox security
+
+// fetchPolyfill implements browser-compatible fetch() API
+// Returns a Promise-like object with json(), text() methods
+func (r *ExtensionRuntime) fetchPolyfill(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.createFetchError("URL is required")
+	}
+
+	urlStr := call.Arguments[0].String()
+
+	// Validate domain
+	if err := r.validateDomain(urlStr); err != nil {
+		GoLog("[Extension:%s] fetch blocked: %v\n", r.extensionID, err)
+		return r.createFetchError(err.Error())
+	}
+
+	// Parse options
+	method := "GET"
+	var bodyStr string
+	headers := make(map[string]string)
+
+	if len(call.Arguments) > 1 && !goja.IsUndefined(call.Arguments[1]) && !goja.IsNull(call.Arguments[1]) {
+		optionsObj := call.Arguments[1].Export()
+		if opts, ok := optionsObj.(map[string]interface{}); ok {
+			// Method
+			if m, ok := opts["method"].(string); ok {
+				method = strings.ToUpper(m)
+			}
+
+			// Body - support string, object (auto-stringify), or nil
+			if bodyArg, ok := opts["body"]; ok && bodyArg != nil {
+				switch v := bodyArg.(type) {
+				case string:
+					bodyStr = v
+				case map[string]interface{}, []interface{}:
+					jsonBytes, err := json.Marshal(v)
+					if err != nil {
+						return r.createFetchError(fmt.Sprintf("failed to stringify body: %v", err))
+					}
+					bodyStr = string(jsonBytes)
+				default:
+					bodyStr = fmt.Sprintf("%v", v)
+				}
+			}
+
+			// Headers
+			if h, ok := opts["headers"]; ok && h != nil {
+				switch hv := h.(type) {
+				case map[string]interface{}:
+					for k, v := range hv {
+						headers[k] = fmt.Sprintf("%v", v)
+					}
+				}
+			}
+		}
+	}
+
+	// Create HTTP request
+	var reqBody io.Reader
+	if bodyStr != "" {
+		reqBody = strings.NewReader(bodyStr)
+	}
+
+	req, err := http.NewRequest(method, urlStr, reqBody)
+	if err != nil {
+		return r.createFetchError(err.Error())
+	}
+
+	// Set headers - user headers first
+	for k, v := range headers {
+		req.Header.Set(k, v)
+	}
+	// Set defaults if not provided
+	if req.Header.Get("User-Agent") == "" {
+		req.Header.Set("User-Agent", "SpotiFLAC-Extension/1.0")
+	}
+	if bodyStr != "" && req.Header.Get("Content-Type") == "" {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
+	// Execute request
+	resp, err := r.httpClient.Do(req)
+	if err != nil {
+		return r.createFetchError(err.Error())
+	}
+	defer resp.Body.Close()
+
+	// Read body
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return r.createFetchError(err.Error())
+	}
+
+	// Extract response headers
+	respHeaders := make(map[string]interface{})
+	for k, v := range resp.Header {
+		if len(v) == 1 {
+			respHeaders[k] = v[0]
+		} else {
+			respHeaders[k] = v
+		}
+	}
+
+	// Create Response object (browser-compatible)
+	responseObj := r.vm.NewObject()
+	responseObj.Set("ok", resp.StatusCode >= 200 && resp.StatusCode < 300)
+	responseObj.Set("status", resp.StatusCode)
+	responseObj.Set("statusText", http.StatusText(resp.StatusCode))
+	responseObj.Set("headers", respHeaders)
+	responseObj.Set("url", urlStr)
+
+	// Store body for methods
+	bodyString := string(body)
+
+	// text() method - returns body as string
+	responseObj.Set("text", func(call goja.FunctionCall) goja.Value {
+		return r.vm.ToValue(bodyString)
+	})
+
+	// json() method - parses body as JSON
+	responseObj.Set("json", func(call goja.FunctionCall) goja.Value {
+		var result interface{}
+		if err := json.Unmarshal(body, &result); err != nil {
+			GoLog("[Extension:%s] fetch json() parse error: %v\n", r.extensionID, err)
+			return goja.Undefined()
+		}
+		return r.vm.ToValue(result)
+	})
+
+	// arrayBuffer() method - returns body as array (simplified)
+	responseObj.Set("arrayBuffer", func(call goja.FunctionCall) goja.Value {
+		// Return as array of bytes
+		byteArray := make([]interface{}, len(body))
+		for i, b := range body {
+			byteArray[i] = int(b)
+		}
+		return r.vm.ToValue(byteArray)
+	})
+
+	return responseObj
+}
+
+// createFetchError creates a fetch error response
+func (r *ExtensionRuntime) createFetchError(message string) goja.Value {
+	errorObj := r.vm.NewObject()
+	errorObj.Set("ok", false)
+	errorObj.Set("status", 0)
+	errorObj.Set("statusText", "Network Error")
+	errorObj.Set("error", message)
+	errorObj.Set("text", func(call goja.FunctionCall) goja.Value {
+		return r.vm.ToValue("")
+	})
+	errorObj.Set("json", func(call goja.FunctionCall) goja.Value {
+		return goja.Undefined()
+	})
+	return errorObj
+}
+
+// atobPolyfill implements browser atob() - decode base64 to string
+func (r *ExtensionRuntime) atobPolyfill(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue("")
+	}
+	input := call.Arguments[0].String()
+	decoded, err := base64.StdEncoding.DecodeString(input)
+	if err != nil {
+		// Try URL-safe base64
+		decoded, err = base64.URLEncoding.DecodeString(input)
+		if err != nil {
+			GoLog("[Extension:%s] atob decode error: %v\n", r.extensionID, err)
+			return r.vm.ToValue("")
+		}
+	}
+	return r.vm.ToValue(string(decoded))
+}
+
+// btoaPolyfill implements browser btoa() - encode string to base64
+func (r *ExtensionRuntime) btoaPolyfill(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue("")
+	}
+	input := call.Arguments[0].String()
+	return r.vm.ToValue(base64.StdEncoding.EncodeToString([]byte(input)))
+}
+
+// registerTextEncoderDecoder registers TextEncoder and TextDecoder classes
+func (r *ExtensionRuntime) registerTextEncoderDecoder(vm *goja.Runtime) {
+	// TextEncoder constructor
+	vm.Set("TextEncoder", func(call goja.ConstructorCall) *goja.Object {
+		encoder := call.This
+		encoder.Set("encoding", "utf-8")
+
+		// encode() method - string to Uint8Array
+		encoder.Set("encode", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) < 1 {
+				return vm.ToValue([]byte{})
+			}
+			input := call.Arguments[0].String()
+			bytes := []byte(input)
+
+			// Return as array (Uint8Array-like)
+			result := make([]interface{}, len(bytes))
+			for i, b := range bytes {
+				result[i] = int(b)
+			}
+			return vm.ToValue(result)
+		})
+
+		// encodeInto() method
+		encoder.Set("encodeInto", func(call goja.FunctionCall) goja.Value {
+			// Simplified implementation
+			if len(call.Arguments) < 2 {
+				return vm.ToValue(map[string]interface{}{"read": 0, "written": 0})
+			}
+			input := call.Arguments[0].String()
+			return vm.ToValue(map[string]interface{}{
+				"read":    len(input),
+				"written": len([]byte(input)),
+			})
+		})
+
+		return nil
+	})
+
+	// TextDecoder constructor
+	vm.Set("TextDecoder", func(call goja.ConstructorCall) *goja.Object {
+		decoder := call.This
+
+		// Get encoding from arguments (default: utf-8)
+		encoding := "utf-8"
+		if len(call.Arguments) > 0 && !goja.IsUndefined(call.Arguments[0]) {
+			encoding = call.Arguments[0].String()
+		}
+		decoder.Set("encoding", encoding)
+		decoder.Set("fatal", false)
+		decoder.Set("ignoreBOM", false)
+
+		// decode() method - Uint8Array to string
+		decoder.Set("decode", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) < 1 {
+				return vm.ToValue("")
+			}
+
+			// Handle different input types
+			input := call.Arguments[0].Export()
+			var bytes []byte
+
+			switch v := input.(type) {
+			case []byte:
+				bytes = v
+			case []interface{}:
+				bytes = make([]byte, len(v))
+				for i, val := range v {
+					switch n := val.(type) {
+					case int64:
+						bytes[i] = byte(n)
+					case float64:
+						bytes[i] = byte(n)
+					case int:
+						bytes[i] = byte(n)
+					}
+				}
+			case string:
+				// Already a string, just return it
+				return vm.ToValue(v)
+			default:
+				return vm.ToValue("")
+			}
+
+			return vm.ToValue(string(bytes))
+		})
+
+		return nil
+	})
+}
+
+// registerURLClass registers the URL class for URL parsing
+func (r *ExtensionRuntime) registerURLClass(vm *goja.Runtime) {
+	vm.Set("URL", func(call goja.ConstructorCall) *goja.Object {
+		urlObj := call.This
+
+		if len(call.Arguments) < 1 {
+			urlObj.Set("href", "")
+			return nil
+		}
+
+		urlStr := call.Arguments[0].String()
+
+		// Handle relative URLs with base
+		if len(call.Arguments) > 1 && !goja.IsUndefined(call.Arguments[1]) {
+			baseStr := call.Arguments[1].String()
+			baseURL, err := url.Parse(baseStr)
+			if err == nil {
+				relURL, err := url.Parse(urlStr)
+				if err == nil {
+					urlStr = baseURL.ResolveReference(relURL).String()
+				}
+			}
+		}
+
+		parsed, err := url.Parse(urlStr)
+		if err != nil {
+			urlObj.Set("href", urlStr)
+			return nil
+		}
+
+		// Set URL properties
+		urlObj.Set("href", parsed.String())
+		urlObj.Set("protocol", parsed.Scheme+":")
+		urlObj.Set("host", parsed.Host)
+		urlObj.Set("hostname", parsed.Hostname())
+		urlObj.Set("port", parsed.Port())
+		urlObj.Set("pathname", parsed.Path)
+		urlObj.Set("search", "")
+		if parsed.RawQuery != "" {
+			urlObj.Set("search", "?"+parsed.RawQuery)
+		}
+		urlObj.Set("hash", "")
+		if parsed.Fragment != "" {
+			urlObj.Set("hash", "#"+parsed.Fragment)
+		}
+		urlObj.Set("origin", parsed.Scheme+"://"+parsed.Host)
+		urlObj.Set("username", parsed.User.Username())
+		password, _ := parsed.User.Password()
+		urlObj.Set("password", password)
+
+		// searchParams object
+		searchParams := vm.NewObject()
+		queryValues := parsed.Query()
+
+		searchParams.Set("get", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) < 1 {
+				return goja.Null()
+			}
+			key := call.Arguments[0].String()
+			if val := queryValues.Get(key); val != "" {
+				return vm.ToValue(val)
+			}
+			return goja.Null()
+		})
+
+		searchParams.Set("getAll", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) < 1 {
+				return vm.ToValue([]string{})
+			}
+			key := call.Arguments[0].String()
+			return vm.ToValue(queryValues[key])
+		})
+
+		searchParams.Set("has", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) < 1 {
+				return vm.ToValue(false)
+			}
+			key := call.Arguments[0].String()
+			return vm.ToValue(queryValues.Has(key))
+		})
+
+		searchParams.Set("toString", func(call goja.FunctionCall) goja.Value {
+			return vm.ToValue(queryValues.Encode())
+		})
+
+		urlObj.Set("searchParams", searchParams)
+
+		// toString method
+		urlObj.Set("toString", func(call goja.FunctionCall) goja.Value {
+			return vm.ToValue(parsed.String())
+		})
+
+		// toJSON method
+		urlObj.Set("toJSON", func(call goja.FunctionCall) goja.Value {
+			return vm.ToValue(parsed.String())
+		})
+
+		return nil
+	})
+
+	// URLSearchParams constructor
+	vm.Set("URLSearchParams", func(call goja.ConstructorCall) *goja.Object {
+		paramsObj := call.This
+		values := url.Values{}
+
+		// Parse initial value if provided
+		if len(call.Arguments) > 0 && !goja.IsUndefined(call.Arguments[0]) {
+			init := call.Arguments[0].Export()
+			switch v := init.(type) {
+			case string:
+				// Parse query string
+				parsed, _ := url.ParseQuery(strings.TrimPrefix(v, "?"))
+				values = parsed
+			case map[string]interface{}:
+				for k, val := range v {
+					values.Set(k, fmt.Sprintf("%v", val))
+				}
+			}
+		}
+
+		paramsObj.Set("append", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) >= 2 {
+				values.Add(call.Arguments[0].String(), call.Arguments[1].String())
+			}
+			return goja.Undefined()
+		})
+
+		paramsObj.Set("delete", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) >= 1 {
+				values.Del(call.Arguments[0].String())
+			}
+			return goja.Undefined()
+		})
+
+		paramsObj.Set("get", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) < 1 {
+				return goja.Null()
+			}
+			if val := values.Get(call.Arguments[0].String()); val != "" {
+				return vm.ToValue(val)
+			}
+			return goja.Null()
+		})
+
+		paramsObj.Set("getAll", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) < 1 {
+				return vm.ToValue([]string{})
+			}
+			return vm.ToValue(values[call.Arguments[0].String()])
+		})
+
+		paramsObj.Set("has", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) < 1 {
+				return vm.ToValue(false)
+			}
+			return vm.ToValue(values.Has(call.Arguments[0].String()))
+		})
+
+		paramsObj.Set("set", func(call goja.FunctionCall) goja.Value {
+			if len(call.Arguments) >= 2 {
+				values.Set(call.Arguments[0].String(), call.Arguments[1].String())
+			}
+			return goja.Undefined()
+		})
+
+		paramsObj.Set("toString", func(call goja.FunctionCall) goja.Value {
+			return vm.ToValue(values.Encode())
+		})
+
+		return nil
+	})
+}
+
+// registerJSONGlobal ensures JSON global is properly set up
+func (r *ExtensionRuntime) registerJSONGlobal(vm *goja.Runtime) {
+	// JSON is already built-in to Goja, but we can enhance it
+	// This ensures JSON.parse and JSON.stringify work as expected
+
+	// The built-in JSON object should already work, but let's verify
+	// and add any missing functionality if needed
+	jsonScript := `
+		if (typeof JSON === 'undefined') {
+			var JSON = {
+				parse: function(text) {
+					return utils.parseJSON(text);
+				},
+				stringify: function(value, replacer, space) {
+					return utils.stringifyJSON(value);
+				}
+			};
+		}
+	`
+	_, _ = vm.RunString(jsonScript)
+}

go_backend/extension_runtime_storage.go

@@ -0,0 +1,377 @@
+// Package gobackend provides Storage and Credentials API for extension runtime
+package gobackend
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"github.com/dop251/goja"
+)
+
+// ==================== Storage API ====================
+
+// getStoragePath returns the path to the extension's storage file
+func (r *ExtensionRuntime) getStoragePath() string {
+	return filepath.Join(r.dataDir, "storage.json")
+}
+
+// loadStorage loads the storage data from disk
+func (r *ExtensionRuntime) loadStorage() (map[string]interface{}, error) {
+	storagePath := r.getStoragePath()
+	data, err := os.ReadFile(storagePath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return make(map[string]interface{}), nil
+		}
+		return nil, err
+	}
+
+	var storage map[string]interface{}
+	if err := json.Unmarshal(data, &storage); err != nil {
+		return nil, err
+	}
+
+	return storage, nil
+}
+
+// saveStorage saves the storage data to disk
+func (r *ExtensionRuntime) saveStorage(storage map[string]interface{}) error {
+	storagePath := r.getStoragePath()
+	data, err := json.MarshalIndent(storage, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(storagePath, data, 0644)
+}
+
+// storageGet retrieves a value from storage
+func (r *ExtensionRuntime) storageGet(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return goja.Undefined()
+	}
+
+	key := call.Arguments[0].String()
+
+	storage, err := r.loadStorage()
+	if err != nil {
+		GoLog("[Extension:%s] Storage load error: %v\n", r.extensionID, err)
+		return goja.Undefined()
+	}
+
+	value, exists := storage[key]
+	if !exists {
+		// Return default value if provided
+		if len(call.Arguments) > 1 {
+			return call.Arguments[1]
+		}
+		return goja.Undefined()
+	}
+
+	return r.vm.ToValue(value)
+}
+
+// storageSet stores a value in storage
+func (r *ExtensionRuntime) storageSet(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(false)
+	}
+
+	key := call.Arguments[0].String()
+	value := call.Arguments[1].Export()
+
+	storage, err := r.loadStorage()
+	if err != nil {
+		GoLog("[Extension:%s] Storage load error: %v\n", r.extensionID, err)
+		return r.vm.ToValue(false)
+	}
+
+	storage[key] = value
+
+	if err := r.saveStorage(storage); err != nil {
+		GoLog("[Extension:%s] Storage save error: %v\n", r.extensionID, err)
+		return r.vm.ToValue(false)
+	}
+
+	return r.vm.ToValue(true)
+}
+
+// storageRemove removes a value from storage
+func (r *ExtensionRuntime) storageRemove(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(false)
+	}
+
+	key := call.Arguments[0].String()
+
+	storage, err := r.loadStorage()
+	if err != nil {
+		GoLog("[Extension:%s] Storage load error: %v\n", r.extensionID, err)
+		return r.vm.ToValue(false)
+	}
+
+	delete(storage, key)
+
+	if err := r.saveStorage(storage); err != nil {
+		GoLog("[Extension:%s] Storage save error: %v\n", r.extensionID, err)
+		return r.vm.ToValue(false)
+	}
+
+	return r.vm.ToValue(true)
+}
+
+// ==================== Credentials API (Encrypted Storage) ====================
+
+// getCredentialsPath returns the path to the extension's encrypted credentials file
+func (r *ExtensionRuntime) getCredentialsPath() string {
+	return filepath.Join(r.dataDir, ".credentials.enc")
+}
+
+// getSaltPath returns the path to the extension's encryption salt file
+func (r *ExtensionRuntime) getSaltPath() string {
+	return filepath.Join(r.dataDir, ".cred_salt")
+}
+
+// getOrCreateSalt gets existing salt or creates a new random one
+func (r *ExtensionRuntime) getOrCreateSalt() ([]byte, error) {
+	saltPath := r.getSaltPath()
+
+	salt, err := os.ReadFile(saltPath)
+	if err == nil && len(salt) == 32 {
+		return salt, nil
+	}
+
+	salt = make([]byte, 32)
+	if _, err := io.ReadFull(rand.Reader, salt); err != nil {
+		return nil, fmt.Errorf("failed to generate salt: %w", err)
+	}
+
+	if err := os.WriteFile(saltPath, salt, 0600); err != nil {
+		return nil, fmt.Errorf("failed to save salt: %w", err)
+	}
+
+	return salt, nil
+}
+
+// getEncryptionKey derives an encryption key from extension ID + random salt
+func (r *ExtensionRuntime) getEncryptionKey() ([]byte, error) {
+	// Get or create per-installation random salt
+	salt, err := r.getOrCreateSalt()
+	if err != nil {
+		return nil, err
+	}
+
+	// Combine extension ID + random salt for key derivation
+	// This makes each installation unique, preventing mass decryption attacks
+	combined := append([]byte(r.extensionID), salt...)
+	hash := sha256.Sum256(combined)
+	return hash[:], nil
+}
+
+// loadCredentials loads and decrypts credentials from disk
+func (r *ExtensionRuntime) loadCredentials() (map[string]interface{}, error) {
+	credPath := r.getCredentialsPath()
+	data, err := os.ReadFile(credPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return make(map[string]interface{}), nil
+		}
+		return nil, err
+	}
+
+	// Decrypt the data
+	key, err := r.getEncryptionKey()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get encryption key: %w", err)
+	}
+	decrypted, err := decryptAES(data, key)
+	if err != nil {
+		return nil, fmt.Errorf("failed to decrypt credentials: %w", err)
+	}
+
+	var creds map[string]interface{}
+	if err := json.Unmarshal(decrypted, &creds); err != nil {
+		return nil, err
+	}
+
+	return creds, nil
+}
+
+// saveCredentials encrypts and saves credentials to disk
+func (r *ExtensionRuntime) saveCredentials(creds map[string]interface{}) error {
+	data, err := json.Marshal(creds)
+	if err != nil {
+		return err
+	}
+
+	key, err := r.getEncryptionKey()
+	if err != nil {
+		return fmt.Errorf("failed to get encryption key: %w", err)
+	}
+	encrypted, err := encryptAES(data, key)
+	if err != nil {
+		return fmt.Errorf("failed to encrypt credentials: %w", err)
+	}
+
+	credPath := r.getCredentialsPath()
+	return os.WriteFile(credPath, encrypted, 0600) // Restrictive permissions
+}
+
+// credentialsStore stores an encrypted credential
+func (r *ExtensionRuntime) credentialsStore(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "key and value are required",
+		})
+	}
+
+	key := call.Arguments[0].String()
+	value := call.Arguments[1].Export()
+
+	creds, err := r.loadCredentials()
+	if err != nil {
+		GoLog("[Extension:%s] Credentials load error: %v\n", r.extensionID, err)
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	creds[key] = value
+
+	if err := r.saveCredentials(creds); err != nil {
+		GoLog("[Extension:%s] Credentials save error: %v\n", r.extensionID, err)
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+	})
+}
+
+// credentialsGet retrieves a decrypted credential
+func (r *ExtensionRuntime) credentialsGet(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return goja.Undefined()
+	}
+
+	key := call.Arguments[0].String()
+
+	creds, err := r.loadCredentials()
+	if err != nil {
+		GoLog("[Extension:%s] Credentials load error: %v\n", r.extensionID, err)
+		return goja.Undefined()
+	}
+
+	value, exists := creds[key]
+	if !exists {
+		// Return default value if provided
+		if len(call.Arguments) > 1 {
+			return call.Arguments[1]
+		}
+		return goja.Undefined()
+	}
+
+	return r.vm.ToValue(value)
+}
+
+// credentialsRemove removes a credential
+func (r *ExtensionRuntime) credentialsRemove(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(false)
+	}
+
+	key := call.Arguments[0].String()
+
+	creds, err := r.loadCredentials()
+	if err != nil {
+		GoLog("[Extension:%s] Credentials load error: %v\n", r.extensionID, err)
+		return r.vm.ToValue(false)
+	}
+
+	delete(creds, key)
+
+	if err := r.saveCredentials(creds); err != nil {
+		GoLog("[Extension:%s] Credentials save error: %v\n", r.extensionID, err)
+		return r.vm.ToValue(false)
+	}
+
+	return r.vm.ToValue(true)
+}
+
+// credentialsHas checks if a credential exists
+func (r *ExtensionRuntime) credentialsHas(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue(false)
+	}
+
+	key := call.Arguments[0].String()
+
+	creds, err := r.loadCredentials()
+	if err != nil {
+		return r.vm.ToValue(false)
+	}
+
+	_, exists := creds[key]
+	return r.vm.ToValue(exists)
+}
+
+// ==================== Crypto Utilities ====================
+
+// encryptAES encrypts data using AES-GCM
+func encryptAES(plaintext []byte, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+
+	ciphertext := gcm.Seal(nonce, nonce, plaintext, nil)
+	return ciphertext, nil
+}
+
+// decryptAES decrypts data using AES-GCM
+func decryptAES(ciphertext []byte, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	nonceSize := gcm.NonceSize()
+	if len(ciphertext) < nonceSize {
+		return nil, fmt.Errorf("ciphertext too short")
+	}
+
+	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
+	plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	return plaintext, nil
+}

go_backend/extension_runtime_utils.go

@@ -0,0 +1,374 @@
+// Package gobackend provides Utility functions for extension runtime
+package gobackend
+
+import (
+	"crypto/hmac"
+	"crypto/md5"
+	"crypto/rand"
+	"crypto/sha1"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/dop251/goja"
+)
+
+// ==================== Utility Functions ====================
+
+// base64Encode encodes a string to base64
+func (r *ExtensionRuntime) base64Encode(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue("")
+	}
+	input := call.Arguments[0].String()
+	return r.vm.ToValue(base64.StdEncoding.EncodeToString([]byte(input)))
+}
+
+// base64Decode decodes a base64 string
+func (r *ExtensionRuntime) base64Decode(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue("")
+	}
+	input := call.Arguments[0].String()
+	decoded, err := base64.StdEncoding.DecodeString(input)
+	if err != nil {
+		return r.vm.ToValue("")
+	}
+	return r.vm.ToValue(string(decoded))
+}
+
+// md5Hash computes MD5 hash of a string
+func (r *ExtensionRuntime) md5Hash(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue("")
+	}
+	input := call.Arguments[0].String()
+	hash := md5.Sum([]byte(input))
+	return r.vm.ToValue(hex.EncodeToString(hash[:]))
+}
+
+// sha256Hash computes SHA256 hash of a string
+func (r *ExtensionRuntime) sha256Hash(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue("")
+	}
+	input := call.Arguments[0].String()
+	hash := sha256.Sum256([]byte(input))
+	return r.vm.ToValue(hex.EncodeToString(hash[:]))
+}
+
+// hmacSHA256 computes HMAC-SHA256 of a message with a key
+func (r *ExtensionRuntime) hmacSHA256(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue("")
+	}
+	message := call.Arguments[0].String()
+	key := call.Arguments[1].String()
+
+	mac := hmac.New(sha256.New, []byte(key))
+	mac.Write([]byte(message))
+	return r.vm.ToValue(hex.EncodeToString(mac.Sum(nil)))
+}
+
+// hmacSHA256Base64 computes HMAC-SHA256 and returns base64 encoded result
+func (r *ExtensionRuntime) hmacSHA256Base64(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue("")
+	}
+	message := call.Arguments[0].String()
+	key := call.Arguments[1].String()
+
+	mac := hmac.New(sha256.New, []byte(key))
+	mac.Write([]byte(message))
+	return r.vm.ToValue(base64.StdEncoding.EncodeToString(mac.Sum(nil)))
+}
+
+// hmacSHA1 computes HMAC-SHA1 of a message with a key (for TOTP)
+// Arguments: message (string or array of bytes), key (string or array of bytes)
+// Returns: array of bytes (for TOTP dynamic truncation)
+func (r *ExtensionRuntime) hmacSHA1(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue([]byte{})
+	}
+
+	var keyBytes []byte
+	keyArg := call.Arguments[0].Export()
+	switch k := keyArg.(type) {
+	case string:
+		keyBytes = []byte(k)
+	case []interface{}:
+		keyBytes = make([]byte, len(k))
+		for i, v := range k {
+			if num, ok := v.(int64); ok {
+				keyBytes[i] = byte(num)
+			} else if num, ok := v.(float64); ok {
+				keyBytes[i] = byte(int(num))
+			}
+		}
+	default:
+		return r.vm.ToValue([]byte{})
+	}
+
+	var msgBytes []byte
+	msgArg := call.Arguments[1].Export()
+	switch m := msgArg.(type) {
+	case string:
+		msgBytes = []byte(m)
+	case []interface{}:
+		msgBytes = make([]byte, len(m))
+		for i, v := range m {
+			if num, ok := v.(int64); ok {
+				msgBytes[i] = byte(num)
+			} else if num, ok := v.(float64); ok {
+				msgBytes[i] = byte(int(num))
+			}
+		}
+	default:
+		return r.vm.ToValue([]byte{})
+	}
+
+	mac := hmac.New(sha1.New, keyBytes)
+	mac.Write(msgBytes)
+	result := mac.Sum(nil)
+
+	jsArray := make([]interface{}, len(result))
+	for i, b := range result {
+		jsArray[i] = int(b)
+	}
+	return r.vm.ToValue(jsArray)
+}
+
+// parseJSON parses a JSON string
+func (r *ExtensionRuntime) parseJSON(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return goja.Undefined()
+	}
+	input := call.Arguments[0].String()
+
+	var result interface{}
+	if err := json.Unmarshal([]byte(input), &result); err != nil {
+		GoLog("[Extension:%s] JSON parse error: %v\n", r.extensionID, err)
+		return goja.Undefined()
+	}
+
+	return r.vm.ToValue(result)
+}
+
+// stringifyJSON converts a value to JSON string
+func (r *ExtensionRuntime) stringifyJSON(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue("")
+	}
+	input := call.Arguments[0].Export()
+
+	data, err := json.Marshal(input)
+	if err != nil {
+		GoLog("[Extension:%s] JSON stringify error: %v\n", r.extensionID, err)
+		return r.vm.ToValue("")
+	}
+
+	return r.vm.ToValue(string(data))
+}
+
+// ==================== Crypto Utilities for Extensions ====================
+
+// cryptoEncrypt encrypts a string using AES-GCM (for extension use)
+func (r *ExtensionRuntime) cryptoEncrypt(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "plaintext and key are required",
+		})
+	}
+
+	plaintext := call.Arguments[0].String()
+	keyStr := call.Arguments[1].String()
+
+	// Derive 32-byte key from provided key string
+	keyHash := sha256.Sum256([]byte(keyStr))
+
+	encrypted, err := encryptAES([]byte(plaintext), keyHash[:])
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"data":    base64.StdEncoding.EncodeToString(encrypted),
+	})
+}
+
+// cryptoDecrypt decrypts a string using AES-GCM (for extension use)
+func (r *ExtensionRuntime) cryptoDecrypt(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 2 {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "ciphertext and key are required",
+		})
+	}
+
+	ciphertextB64 := call.Arguments[0].String()
+	keyStr := call.Arguments[1].String()
+
+	ciphertext, err := base64.StdEncoding.DecodeString(ciphertextB64)
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   "invalid base64 ciphertext",
+		})
+	}
+
+	// Derive 32-byte key from provided key string
+	keyHash := sha256.Sum256([]byte(keyStr))
+
+	decrypted, err := decryptAES(ciphertext, keyHash[:])
+	if err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"data":    string(decrypted),
+	})
+}
+
+// cryptoGenerateKey generates a random encryption key
+func (r *ExtensionRuntime) cryptoGenerateKey(call goja.FunctionCall) goja.Value {
+	length := 32 // Default 256-bit key
+	if len(call.Arguments) > 0 && !goja.IsUndefined(call.Arguments[0]) {
+		if l, ok := call.Arguments[0].Export().(float64); ok {
+			length = int(l)
+		}
+	}
+
+	key := make([]byte, length)
+	if _, err := rand.Read(key); err != nil {
+		return r.vm.ToValue(map[string]interface{}{
+			"success": false,
+			"error":   err.Error(),
+		})
+	}
+
+	return r.vm.ToValue(map[string]interface{}{
+		"success": true,
+		"key":     base64.StdEncoding.EncodeToString(key),
+		"hex":     hex.EncodeToString(key),
+	})
+}
+
+// randomUserAgent returns a random Chrome User-Agent string
+func (r *ExtensionRuntime) randomUserAgent(call goja.FunctionCall) goja.Value {
+	return r.vm.ToValue(getRandomUserAgent())
+}
+
+// ==================== Logging Functions ====================
+
+func (r *ExtensionRuntime) logDebug(call goja.FunctionCall) goja.Value {
+	msg := r.formatLogArgs(call.Arguments)
+	GoLog("[Extension:%s:DEBUG] %s\n", r.extensionID, msg)
+	return goja.Undefined()
+}
+
+func (r *ExtensionRuntime) logInfo(call goja.FunctionCall) goja.Value {
+	msg := r.formatLogArgs(call.Arguments)
+	GoLog("[Extension:%s:INFO] %s\n", r.extensionID, msg)
+	return goja.Undefined()
+}
+
+func (r *ExtensionRuntime) logWarn(call goja.FunctionCall) goja.Value {
+	msg := r.formatLogArgs(call.Arguments)
+	GoLog("[Extension:%s:WARN] %s\n", r.extensionID, msg)
+	return goja.Undefined()
+}
+
+func (r *ExtensionRuntime) logError(call goja.FunctionCall) goja.Value {
+	msg := r.formatLogArgs(call.Arguments)
+	GoLog("[Extension:%s:ERROR] %s\n", r.extensionID, msg)
+	return goja.Undefined()
+}
+
+func (r *ExtensionRuntime) formatLogArgs(args []goja.Value) string {
+	parts := make([]string, len(args))
+	for i, arg := range args {
+		parts[i] = fmt.Sprintf("%v", arg.Export())
+	}
+	return strings.Join(parts, " ")
+}
+
+// ==================== Go Backend Wrappers ====================
+
+func (r *ExtensionRuntime) sanitizeFilenameWrapper(call goja.FunctionCall) goja.Value {
+	if len(call.Arguments) < 1 {
+		return r.vm.ToValue("")
+	}
+	input := call.Arguments[0].String()
+	return r.vm.ToValue(sanitizeFilename(input))
+}
+
+// RegisterGoBackendAPIs adds more Go backend functions to the VM
+func (r *ExtensionRuntime) RegisterGoBackendAPIs(vm *goja.Runtime) {
+	gobackendObj := vm.Get("gobackend")
+	if gobackendObj == nil || goja.IsUndefined(gobackendObj) {
+		gobackendObj = vm.NewObject()
+		vm.Set("gobackend", gobackendObj)
+	}
+
+	obj := gobackendObj.(*goja.Object)
+
+	// Expose sanitizeFilename
+	obj.Set("sanitizeFilename", func(call goja.FunctionCall) goja.Value {
+		if len(call.Arguments) < 1 {
+			return vm.ToValue("")
+		}
+		return vm.ToValue(sanitizeFilename(call.Arguments[0].String()))
+	})
+
+	// Expose getAudioQuality
+	obj.Set("getAudioQuality", func(call goja.FunctionCall) goja.Value {
+		if len(call.Arguments) < 1 {
+			return vm.ToValue(map[string]interface{}{
+				"error": "file path is required",
+			})
+		}
+
+		filePath := call.Arguments[0].String()
+		quality, err := GetAudioQuality(filePath)
+		if err != nil {
+			return vm.ToValue(map[string]interface{}{
+				"error": err.Error(),
+			})
+		}
+
+		return vm.ToValue(map[string]interface{}{
+			"bitDepth":     quality.BitDepth,
+			"sampleRate":   quality.SampleRate,
+			"totalSamples": quality.TotalSamples,
+		})
+	})
+
+	// Expose buildFilename
+	obj.Set("buildFilename", func(call goja.FunctionCall) goja.Value {
+		if len(call.Arguments) < 2 {
+			return vm.ToValue("")
+		}
+
+		template := call.Arguments[0].String()
+		metadataObj := call.Arguments[1].Export()
+
+		metadata, ok := metadataObj.(map[string]interface{})
+		if !ok {
+			return vm.ToValue("")
+		}
+
+		return vm.ToValue(buildFilenameFromTemplate(template, metadata))
+	})
+}

go_backend/extension_settings.go

@@ -0,0 +1,217 @@
+// Package gobackend provides extension settings storage
+package gobackend
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+// ExtensionSettingsStore manages settings for all extensions
+type ExtensionSettingsStore struct {
+	mu       sync.RWMutex
+	dataDir  string
+	settings map[string]map[string]interface{} // extensionID -> settings
+}
+
+// Global settings store
+var (
+	globalSettingsStore     *ExtensionSettingsStore
+	globalSettingsStoreOnce sync.Once
+)
+
+// GetExtensionSettingsStore returns the global settings store
+func GetExtensionSettingsStore() *ExtensionSettingsStore {
+	globalSettingsStoreOnce.Do(func() {
+		globalSettingsStore = &ExtensionSettingsStore{
+			settings: make(map[string]map[string]interface{}),
+		}
+	})
+	return globalSettingsStore
+}
+
+// SetDataDir sets the data directory for settings storage
+func (s *ExtensionSettingsStore) SetDataDir(dataDir string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.dataDir = dataDir
+	if err := os.MkdirAll(dataDir, 0755); err != nil {
+		return fmt.Errorf("failed to create settings directory: %w", err)
+	}
+
+	return s.loadAllSettings()
+}
+
+// getSettingsPath returns the path to an extension's settings file
+func (s *ExtensionSettingsStore) getSettingsPath(extensionID string) string {
+	return filepath.Join(s.dataDir, extensionID, "settings.json")
+}
+
+// loadAllSettings loads settings for all extensions from disk
+func (s *ExtensionSettingsStore) loadAllSettings() error {
+	entries, err := os.ReadDir(s.dataDir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+
+	for _, entry := range entries {
+		if entry.IsDir() {
+			extensionID := entry.Name()
+			settings, err := s.loadSettings(extensionID)
+			if err != nil {
+				GoLog("[ExtensionSettings] Failed to load settings for %s: %v\n", extensionID, err)
+				continue
+			}
+			s.settings[extensionID] = settings
+		}
+	}
+
+	return nil
+}
+
+// loadSettings loads settings for a specific extension
+func (s *ExtensionSettingsStore) loadSettings(extensionID string) (map[string]interface{}, error) {
+	settingsPath := s.getSettingsPath(extensionID)
+	data, err := os.ReadFile(settingsPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return make(map[string]interface{}), nil
+		}
+		return nil, err
+	}
+
+	var settings map[string]interface{}
+	if err := json.Unmarshal(data, &settings); err != nil {
+		return nil, err
+	}
+
+	return settings, nil
+}
+
+// saveSettings saves settings for a specific extension
+func (s *ExtensionSettingsStore) saveSettings(extensionID string, settings map[string]interface{}) error {
+	settingsPath := s.getSettingsPath(extensionID)
+
+	dir := filepath.Dir(settingsPath)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return err
+	}
+
+	data, err := json.MarshalIndent(settings, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(settingsPath, data, 0644)
+}
+
+// Get retrieves a setting value for an extension
+// Returns error if extension or key not found (gomobile compatible)
+func (s *ExtensionSettingsStore) Get(extensionID, key string) (interface{}, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	extSettings, exists := s.settings[extensionID]
+	if !exists {
+		return nil, fmt.Errorf("extension '%s' settings not found", extensionID)
+	}
+
+	value, exists := extSettings[key]
+	if !exists {
+		return nil, fmt.Errorf("setting '%s' not found for extension '%s'", key, extensionID)
+	}
+	return value, nil
+}
+
+// GetAll retrieves all settings for an extension
+func (s *ExtensionSettingsStore) GetAll(extensionID string) map[string]interface{} {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	extSettings, exists := s.settings[extensionID]
+	if !exists {
+		return make(map[string]interface{})
+	}
+
+	// Return a copy
+	result := make(map[string]interface{})
+	for k, v := range extSettings {
+		result[k] = v
+	}
+	return result
+}
+
+// Set stores a setting value for an extension
+func (s *ExtensionSettingsStore) Set(extensionID, key string, value interface{}) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if _, exists := s.settings[extensionID]; !exists {
+		s.settings[extensionID] = make(map[string]interface{})
+	}
+
+	s.settings[extensionID][key] = value
+
+	return s.saveSettings(extensionID, s.settings[extensionID])
+}
+
+// SetAll stores all settings for an extension
+func (s *ExtensionSettingsStore) SetAll(extensionID string, settings map[string]interface{}) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.settings[extensionID] = settings
+
+	// Persist to disk
+	return s.saveSettings(extensionID, settings)
+}
+
+// Remove removes a setting for an extension
+func (s *ExtensionSettingsStore) Remove(extensionID, key string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	extSettings, exists := s.settings[extensionID]
+	if !exists {
+		return nil
+	}
+
+	delete(extSettings, key)
+
+	// Persist to disk
+	return s.saveSettings(extensionID, extSettings)
+}
+
+// RemoveAll removes all settings for an extension
+func (s *ExtensionSettingsStore) RemoveAll(extensionID string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	delete(s.settings, extensionID)
+
+	settingsPath := s.getSettingsPath(extensionID)
+	if err := os.Remove(settingsPath); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+
+	return nil
+}
+
+// GetAllExtensionSettings returns settings for all extensions as JSON
+func (s *ExtensionSettingsStore) GetAllExtensionSettingsJSON() (string, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	data, err := json.Marshal(s.settings)
+	if err != nil {
+		return "", err
+	}
+
+	return string(data), nil
+}

go_backend/extension_store.go

@@ -0,0 +1,451 @@
+package gobackend
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+// Extension categories
+const (
+	CategoryMetadata    = "metadata"
+	CategoryDownload    = "download"
+	CategoryUtility     = "utility"
+	CategoryLyrics      = "lyrics"
+	CategoryIntegration = "integration"
+)
+
+// StoreExtension represents an extension in the store
+type StoreExtension struct {
+	ID            string   `json:"id"`
+	Name          string   `json:"name"`
+	DisplayName   string   `json:"display_name,omitempty"`
+	Version       string   `json:"version"`
+	Author        string   `json:"author"`
+	Description   string   `json:"description"`
+	DownloadURL   string   `json:"download_url,omitempty"`
+	IconURL       string   `json:"icon_url,omitempty"`
+	Category      string   `json:"category"`
+	Tags          []string `json:"tags,omitempty"`
+	Downloads     int      `json:"downloads"`
+	UpdatedAt     string   `json:"updated_at"`
+	MinAppVersion string   `json:"min_app_version,omitempty"`
+	DisplayNameAlt   string `json:"displayName,omitempty"`
+	DownloadURLAlt   string `json:"downloadUrl,omitempty"`
+	IconURLAlt       string `json:"iconUrl,omitempty"`
+	MinAppVersionAlt string `json:"minAppVersion,omitempty"`
+}
+
+// getDisplayName returns display name, falling back to name (private to avoid gomobile conflict)
+func (e *StoreExtension) getDisplayName() string {
+	if e.DisplayName != "" {
+		return e.DisplayName
+	}
+	if e.DisplayNameAlt != "" {
+		return e.DisplayNameAlt
+	}
+	return e.Name
+}
+
+// getDownloadURL returns download URL from either field (private to avoid gomobile conflict)
+func (e *StoreExtension) getDownloadURL() string {
+	if e.DownloadURL != "" {
+		return e.DownloadURL
+	}
+	return e.DownloadURLAlt
+}
+
+// getIconURL returns icon URL from either field (private to avoid gomobile conflict)
+func (e *StoreExtension) getIconURL() string {
+	if e.IconURL != "" {
+		return e.IconURL
+	}
+	return e.IconURLAlt
+}
+
+// getMinAppVersion returns min app version from either field (private to avoid gomobile conflict)
+func (e *StoreExtension) getMinAppVersion() string {
+	if e.MinAppVersion != "" {
+		return e.MinAppVersion
+	}
+	return e.MinAppVersionAlt
+}
+
+// StoreRegistry represents the extension registry
+type StoreRegistry struct {
+	Version    int              `json:"version"`
+	UpdatedAt  string           `json:"updated_at"`
+	Extensions []StoreExtension `json:"extensions"`
+}
+
+// StoreExtensionResponse is the normalized response sent to Flutter
+type StoreExtensionResponse struct {
+	ID               string   `json:"id"`
+	Name             string   `json:"name"`
+	DisplayName      string   `json:"display_name"`
+	Version          string   `json:"version"`
+	Author           string   `json:"author"`
+	Description      string   `json:"description"`
+	DownloadURL      string   `json:"download_url"`
+	IconURL          string   `json:"icon_url,omitempty"`
+	Category         string   `json:"category"`
+	Tags             []string `json:"tags,omitempty"`
+	Downloads        int      `json:"downloads"`
+	UpdatedAt        string   `json:"updated_at"`
+	MinAppVersion    string   `json:"min_app_version,omitempty"`
+	IsInstalled      bool     `json:"is_installed"`
+	InstalledVersion string   `json:"installed_version,omitempty"`
+	HasUpdate        bool     `json:"has_update"`
+}
+
+// ToResponse converts StoreExtension to normalized response
+func (e *StoreExtension) ToResponse() StoreExtensionResponse {
+	return StoreExtensionResponse{
+		ID:            e.ID,
+		Name:          e.Name,
+		DisplayName:   e.getDisplayName(),
+		Version:       e.Version,
+		Author:        e.Author,
+		Description:   e.Description,
+		DownloadURL:   e.getDownloadURL(),
+		IconURL:       e.getIconURL(),
+		Category:      e.Category,
+		Tags:          e.Tags,
+		Downloads:     e.Downloads,
+		UpdatedAt:     e.UpdatedAt,
+		MinAppVersion: e.getMinAppVersion(),
+	}
+}
+
+// ExtensionStore manages the extension store
+type ExtensionStore struct {
+	registryURL string
+	cacheDir    string
+	cache       *StoreRegistry
+	cacheMu     sync.RWMutex
+	cacheTime   time.Time
+	cacheTTL    time.Duration
+}
+
+var (
+	extensionStore   *ExtensionStore
+	extensionStoreMu sync.Mutex
+)
+
+const (
+	defaultRegistryURL = "https://raw.githubusercontent.com/zarzet/SpotiFLAC-Extension/main/registry.json"
+	cacheTTL           = 30 * time.Minute
+	cacheFileName      = "store_cache.json"
+)
+
+// InitExtensionStore initializes the extension store
+func InitExtensionStore(cacheDir string) *ExtensionStore {
+	extensionStoreMu.Lock()
+	defer extensionStoreMu.Unlock()
+
+	if extensionStore == nil {
+		extensionStore = &ExtensionStore{
+			registryURL: defaultRegistryURL,
+			cacheDir:    cacheDir,
+			cacheTTL:    cacheTTL,
+		}
+		// Try to load from disk cache
+		extensionStore.loadDiskCache()
+	}
+	return extensionStore
+}
+
+// GetExtensionStore returns the singleton store instance
+func GetExtensionStore() *ExtensionStore {
+	extensionStoreMu.Lock()
+	defer extensionStoreMu.Unlock()
+	return extensionStore
+}
+
+// loadDiskCache loads cached registry from disk
+func (s *ExtensionStore) loadDiskCache() {
+	if s.cacheDir == "" {
+		return
+	}
+
+	cachePath := filepath.Join(s.cacheDir, cacheFileName)
+	data, err := os.ReadFile(cachePath)
+	if err != nil {
+		return
+	}
+
+	var cacheData struct {
+		Registry  StoreRegistry `json:"registry"`
+		CacheTime int64         `json:"cache_time"`
+	}
+
+	if err := json.Unmarshal(data, &cacheData); err != nil {
+		return
+	}
+
+	s.cache = &cacheData.Registry
+	s.cacheTime = time.Unix(cacheData.CacheTime, 0)
+	LogDebug("ExtensionStore", "Loaded %d extensions from disk cache", len(s.cache.Extensions))
+}
+
+// saveDiskCache saves registry to disk cache
+func (s *ExtensionStore) saveDiskCache() {
+	if s.cacheDir == "" || s.cache == nil {
+		return
+	}
+
+	cacheData := struct {
+		Registry  StoreRegistry `json:"registry"`
+		CacheTime int64         `json:"cache_time"`
+	}{
+		Registry:  *s.cache,
+		CacheTime: s.cacheTime.Unix(),
+	}
+
+	data, err := json.Marshal(cacheData)
+	if err != nil {
+		return
+	}
+
+	cachePath := filepath.Join(s.cacheDir, cacheFileName)
+	os.WriteFile(cachePath, data, 0644)
+}
+
+// FetchRegistry fetches the extension registry from GitHub
+func (s *ExtensionStore) FetchRegistry(forceRefresh bool) (*StoreRegistry, error) {
+	s.cacheMu.Lock()
+	defer s.cacheMu.Unlock()
+
+	// Return cached if valid and not forcing refresh
+	if !forceRefresh && s.cache != nil && time.Since(s.cacheTime) < s.cacheTTL {
+		LogDebug("ExtensionStore", "Using cached registry (%d extensions)", len(s.cache.Extensions))
+		return s.cache, nil
+	}
+
+	LogInfo("ExtensionStore", "Fetching registry from %s", s.registryURL)
+
+	client := &http.Client{Timeout: 30 * time.Second}
+	resp, err := client.Get(s.registryURL)
+	if err != nil {
+		// Return cached data if available on network error
+		if s.cache != nil {
+			LogWarn("ExtensionStore", "Network error, using cached registry: %v", err)
+			return s.cache, nil
+		}
+		return nil, fmt.Errorf("failed to fetch registry: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		if s.cache != nil {
+			LogWarn("ExtensionStore", "HTTP %d, using cached registry", resp.StatusCode)
+			return s.cache, nil
+		}
+		return nil, fmt.Errorf("registry returned HTTP %d", resp.StatusCode)
+	}
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read registry: %w", err)
+	}
+
+	var registry StoreRegistry
+	if err := json.Unmarshal(body, &registry); err != nil {
+		return nil, fmt.Errorf("failed to parse registry: %w", err)
+	}
+
+	s.cache = &registry
+	s.cacheTime = time.Now()
+	s.saveDiskCache()
+
+	LogInfo("ExtensionStore", "Fetched %d extensions from registry", len(registry.Extensions))
+	return &registry, nil
+}
+
+// GetExtensionsWithStatus returns extensions with installation status
+func (s *ExtensionStore) GetExtensionsWithStatus() ([]StoreExtensionResponse, error) {
+	registry, err := s.FetchRegistry(false)
+	if err != nil {
+		return nil, err
+	}
+
+	manager := GetExtensionManager()
+	installed := make(map[string]string) // id -> version
+
+	if manager != nil {
+		for _, ext := range manager.GetAllExtensions() {
+			installed[ext.ID] = ext.Manifest.Version
+		}
+	}
+
+	result := make([]StoreExtensionResponse, len(registry.Extensions))
+	for i, ext := range registry.Extensions {
+		resp := ext.ToResponse()
+
+		if installedVersion, ok := installed[ext.ID]; ok {
+			resp.IsInstalled = true
+			resp.InstalledVersion = installedVersion
+			resp.HasUpdate = compareVersions(ext.Version, installedVersion) > 0
+		}
+
+		result[i] = resp
+	}
+
+	return result, nil
+}
+
+// DownloadExtension downloads an extension package to the specified path
+func (s *ExtensionStore) DownloadExtension(extensionID string, destPath string) error {
+	registry, err := s.FetchRegistry(false)
+	if err != nil {
+		return err
+	}
+
+	var ext *StoreExtension
+	for _, e := range registry.Extensions {
+		if e.ID == extensionID {
+			ext = &e
+			break
+		}
+	}
+
+	if ext == nil {
+		return fmt.Errorf("extension %s not found in store", extensionID)
+	}
+
+	LogInfo("ExtensionStore", "Downloading %s from %s", ext.getDisplayName(), ext.getDownloadURL())
+
+	client := &http.Client{Timeout: 5 * time.Minute}
+	resp, err := client.Get(ext.getDownloadURL())
+	if err != nil {
+		return fmt.Errorf("failed to download: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("download returned HTTP %d", resp.StatusCode)
+	}
+
+	out, err := os.Create(destPath)
+	if err != nil {
+		return fmt.Errorf("failed to create file: %w", err)
+	}
+	defer out.Close()
+
+	_, err = io.Copy(out, resp.Body)
+	if err != nil {
+		os.Remove(destPath)
+		return fmt.Errorf("failed to write file: %w", err)
+	}
+
+	LogInfo("ExtensionStore", "Downloaded %s to %s", ext.getDisplayName(), destPath)
+	return nil
+}
+
+// GetCategories returns all available categories
+func (s *ExtensionStore) GetCategories() []string {
+	return []string{
+		CategoryMetadata,
+		CategoryDownload,
+		CategoryUtility,
+		CategoryLyrics,
+		CategoryIntegration,
+	}
+}
+
+// SearchExtensions searches extensions by query
+func (s *ExtensionStore) SearchExtensions(query string, category string) ([]StoreExtensionResponse, error) {
+	extensions, err := s.GetExtensionsWithStatus()
+	if err != nil {
+		return nil, err
+	}
+
+	if query == "" && category == "" {
+		return extensions, nil
+	}
+
+	var result []StoreExtensionResponse
+	queryLower := toLower(query)
+
+	for _, ext := range extensions {
+		// Filter by category
+		if category != "" && ext.Category != category {
+			continue
+		}
+
+		// Filter by query
+		if query != "" {
+			if !containsIgnoreCase(ext.Name, queryLower) &&
+				!containsIgnoreCase(ext.DisplayName, queryLower) &&
+				!containsIgnoreCase(ext.Description, queryLower) &&
+				!containsIgnoreCase(ext.Author, queryLower) {
+				// Check tags
+				found := false
+				for _, tag := range ext.Tags {
+					if containsIgnoreCase(tag, queryLower) {
+						found = true
+						break
+					}
+				}
+				if !found {
+					continue
+				}
+			}
+		}
+
+		result = append(result, ext)
+	}
+
+	return result, nil
+}
+
+// ClearCache clears the in-memory and disk cache
+func (s *ExtensionStore) ClearCache() {
+	s.cacheMu.Lock()
+	defer s.cacheMu.Unlock()
+
+	s.cache = nil
+	s.cacheTime = time.Time{}
+
+	if s.cacheDir != "" {
+		cachePath := filepath.Join(s.cacheDir, cacheFileName)
+		os.Remove(cachePath)
+	}
+
+	LogInfo("ExtensionStore", "Cache cleared")
+}
+
+// Helper: case-insensitive contains
+func containsIgnoreCase(s, substr string) bool {
+	return containsStr(toLower(s), substr)
+}
+
+func toLower(s string) string {
+	result := make([]byte, len(s))
+	for i := 0; i < len(s); i++ {
+		c := s[i]
+		if c >= 'A' && c <= 'Z' {
+			c += 'a' - 'A'
+		}
+		result[i] = c
+	}
+	return string(result)
+}
+
+func containsStr(s, substr string) bool {
+	return len(substr) == 0 || (len(s) >= len(substr) && findSubstring(s, substr) >= 0)
+}
+
+func findSubstring(s, substr string) int {
+	for i := 0; i <= len(s)-len(substr); i++ {
+		if s[i:i+len(substr)] == substr {
+			return i
+		}
+	}
+	return -1
+}

go_backend/extension_test.go

@@ -0,0 +1,329 @@
+package gobackend
+
+import (
+	"path/filepath"
+	"testing"
+
+	"github.com/dop251/goja"
+)
+
+func TestParseManifest_Valid(t *testing.T) {
+	validManifest := `{
+		"name": "test-provider",
+		"displayName": "Test Provider",
+		"version": "1.0.0",
+		"author": "Test Author",
+		"description": "A test extension",
+		"type": ["metadata_provider"],
+		"permissions": {
+			"network": ["api.test.com"],
+			"storage": true
+		}
+	}`
+
+	manifest, err := ParseManifest([]byte(validManifest))
+	if err != nil {
+		t.Fatalf("Expected valid manifest to parse, got error: %v", err)
+	}
+
+	if manifest.Name != "test-provider" {
+		t.Errorf("Expected name 'test-provider', got '%s'", manifest.Name)
+	}
+
+	if manifest.Version != "1.0.0" {
+		t.Errorf("Expected version '1.0.0', got '%s'", manifest.Version)
+	}
+
+	if !manifest.IsMetadataProvider() {
+		t.Error("Expected IsMetadataProvider() to return true")
+	}
+
+	if manifest.IsDownloadProvider() {
+		t.Error("Expected IsDownloadProvider() to return false")
+	}
+}
+
+func TestParseManifest_MissingName(t *testing.T) {
+	invalidManifest := `{
+		"version": "1.0.0",
+		"author": "Test Author",
+		"description": "A test extension",
+		"type": ["metadata_provider"]
+	}`
+
+	_, err := ParseManifest([]byte(invalidManifest))
+	if err == nil {
+		t.Fatal("Expected error for missing name")
+	}
+}
+
+func TestParseManifest_MissingType(t *testing.T) {
+	invalidManifest := `{
+		"name": "test-provider",
+		"version": "1.0.0",
+		"author": "Test Author",
+		"description": "A test extension"
+	}`
+
+	_, err := ParseManifest([]byte(invalidManifest))
+	if err == nil {
+		t.Fatal("Expected error for missing type")
+	}
+}
+
+func TestIsDomainAllowed(t *testing.T) {
+	manifest := &ExtensionManifest{
+		Permissions: ExtensionPermissions{
+			Network: []string{"api.test.com", "*.example.com"},
+		},
+	}
+
+	tests := []struct {
+		domain   string
+		expected bool
+	}{
+		{"api.test.com", true},
+		{"api.example.com", true},
+		{"sub.example.com", true},
+		{"notallowed.com", false},
+		{"test.com", false},
+	}
+
+	for _, tt := range tests {
+		result := manifest.IsDomainAllowed(tt.domain)
+		if result != tt.expected {
+			t.Errorf("IsDomainAllowed(%s) = %v, expected %v", tt.domain, result, tt.expected)
+		}
+	}
+}
+
+func TestExtensionRuntime_NetworkSandbox(t *testing.T) {
+	// Create a mock extension with limited network permissions
+	ext := &LoadedExtension{
+		ID: "test-ext",
+		Manifest: &ExtensionManifest{
+			Name: "test-ext",
+			Permissions: ExtensionPermissions{
+				Network: []string{"api.allowed.com", "*.wildcard.com"},
+			},
+		},
+		DataDir: t.TempDir(),
+	}
+
+	runtime := NewExtensionRuntime(ext)
+
+	// Test allowed domains
+	if err := runtime.validateDomain("https://api.allowed.com/path"); err != nil {
+		t.Errorf("Expected api.allowed.com to be allowed, got error: %v", err)
+	}
+
+	if err := runtime.validateDomain("https://sub.wildcard.com/path"); err != nil {
+		t.Errorf("Expected sub.wildcard.com to be allowed (wildcard), got error: %v", err)
+	}
+
+	// Test blocked domains
+	if err := runtime.validateDomain("https://blocked.com/path"); err == nil {
+		t.Error("Expected blocked.com to be denied")
+	}
+
+	if err := runtime.validateDomain("https://notallowed.com/path"); err == nil {
+		t.Error("Expected notallowed.com to be denied")
+	}
+}
+
+func TestExtensionRuntime_FileSandbox(t *testing.T) {
+	tempDir := t.TempDir()
+
+	ext := &LoadedExtension{
+		ID: "test-ext",
+		Manifest: &ExtensionManifest{
+			Name: "test-ext",
+			Permissions: ExtensionPermissions{
+				File: true, // Enable file permission for test
+			},
+		},
+		DataDir: tempDir,
+	}
+
+	runtime := NewExtensionRuntime(ext)
+
+	// Test valid path within sandbox
+	validPath, err := runtime.validatePath("test.txt")
+	if err != nil {
+		t.Errorf("Expected relative path to be valid, got error: %v", err)
+	}
+	if validPath == "" {
+		t.Error("Expected non-empty path")
+	}
+
+	// Test path traversal attack
+	_, err = runtime.validatePath("../../../etc/passwd")
+	if err == nil {
+		t.Error("Expected path traversal to be blocked")
+	}
+
+	// Test nested path within sandbox (should be allowed)
+	nestedPath, err := runtime.validatePath("subdir/file.txt")
+	if err != nil {
+		t.Errorf("Expected nested path to be valid, got error: %v", err)
+	}
+	if nestedPath == "" {
+		t.Error("Expected non-empty nested path")
+	}
+
+	// Test absolute path should be blocked (security fix)
+	// Use platform-appropriate absolute path
+	var absPath string
+	if filepath.IsAbs("C:\\Windows\\System32") {
+		absPath = "C:\\Windows\\System32\\test.txt" // Windows
+	} else {
+		absPath = "/etc/passwd" // Unix
+	}
+	_, err = runtime.validatePath(absPath)
+	if err == nil {
+		t.Error("Expected absolute path to be blocked")
+	}
+
+	// Test that extension without file permission is blocked
+	extNoFile := &LoadedExtension{
+		ID: "test-ext-no-file",
+		Manifest: &ExtensionManifest{
+			Name: "test-ext-no-file",
+			Permissions: ExtensionPermissions{
+				File: false, // No file permission
+			},
+		},
+		DataDir: tempDir,
+	}
+	runtimeNoFile := NewExtensionRuntime(extNoFile)
+	_, err = runtimeNoFile.validatePath("test.txt")
+	if err == nil {
+		t.Error("Expected file access to be denied without file permission")
+	}
+}
+
+func TestExtensionRuntime_UtilityFunctions(t *testing.T) {
+	ext := &LoadedExtension{
+		ID: "test-ext",
+		Manifest: &ExtensionManifest{
+			Name: "test-ext",
+		},
+		DataDir: t.TempDir(),
+	}
+
+	runtime := NewExtensionRuntime(ext)
+	vm := goja.New()
+	runtime.RegisterAPIs(vm)
+
+	// Test base64 encode/decode
+	result, err := vm.RunString(`utils.base64Encode("hello")`)
+	if err != nil {
+		t.Fatalf("base64Encode failed: %v", err)
+	}
+	if result.String() != "aGVsbG8=" {
+		t.Errorf("Expected 'aGVsbG8=', got '%s'", result.String())
+	}
+
+	result, err = vm.RunString(`utils.base64Decode("aGVsbG8=")`)
+	if err != nil {
+		t.Fatalf("base64Decode failed: %v", err)
+	}
+	if result.String() != "hello" {
+		t.Errorf("Expected 'hello', got '%s'", result.String())
+	}
+
+	// Test MD5
+	result, err = vm.RunString(`utils.md5("hello")`)
+	if err != nil {
+		t.Fatalf("md5 failed: %v", err)
+	}
+	if result.String() != "5d41402abc4b2a76b9719d911017c592" {
+		t.Errorf("Expected '5d41402abc4b2a76b9719d911017c592', got '%s'", result.String())
+	}
+
+	// Test JSON parse/stringify
+	result, err = vm.RunString(`utils.stringifyJSON({name: "test", value: 123})`)
+	if err != nil {
+		t.Fatalf("stringifyJSON failed: %v", err)
+	}
+	// JSON output may vary in order, just check it's valid
+	if result.String() == "" {
+		t.Error("Expected non-empty JSON string")
+	}
+}
+
+func TestExtensionRuntime_SSRFProtection(t *testing.T) {
+	// Create extension with limited network permissions
+	ext := &LoadedExtension{
+		ID: "test-ext",
+		Manifest: &ExtensionManifest{
+			Name: "test-ext",
+			Permissions: ExtensionPermissions{
+				Network: []string{"api.example.com"},
+			},
+		},
+		DataDir: t.TempDir(),
+	}
+
+	runtime := NewExtensionRuntime(ext)
+
+	// Test that private IPs are blocked (SSRF protection)
+	privateIPs := []string{
+		"http://localhost/admin",
+		"http://127.0.0.1/admin",
+		"http://192.168.1.1/admin",
+		"http://10.0.0.1/admin",
+		"http://172.16.0.1/admin",
+		"http://169.254.169.254/latest/meta-data/", // AWS metadata
+		"http://router.local/admin",
+	}
+
+	for _, url := range privateIPs {
+		err := runtime.validateDomain(url)
+		if err == nil {
+			t.Errorf("Expected private IP/host '%s' to be blocked", url)
+		}
+	}
+
+	// Test that allowed public domain still works
+	if err := runtime.validateDomain("https://api.example.com/path"); err != nil {
+		t.Errorf("Expected api.example.com to be allowed, got error: %v", err)
+	}
+}
+
+func TestIsPrivateIP(t *testing.T) {
+	tests := []struct {
+		host     string
+		expected bool
+	}{
+		// Private IPs should be blocked
+		{"localhost", true},
+		{"127.0.0.1", true},
+		{"127.0.0.2", true},
+		{"10.0.0.1", true},
+		{"10.255.255.255", true},
+		{"172.16.0.1", true},
+		{"172.31.255.255", true},
+		{"192.168.0.1", true},
+		{"192.168.255.255", true},
+		{"169.254.169.254", true}, // AWS metadata
+		{"router.local", true},
+		{"mydevice.local", true},
+
+		// Public IPs should be allowed
+		{"8.8.8.8", false},
+		{"1.1.1.1", false},
+		{"api.example.com", false},
+		{"google.com", false},
+		{"172.15.0.1", false},  // Just outside 172.16-31 range
+		{"172.32.0.1", false},  // Just outside 172.16-31 range
+		{"192.167.0.1", false}, // Not 192.168.x.x
+	}
+
+	for _, tt := range tests {
+		result := isPrivateIP(tt.host)
+		if result != tt.expected {
+			t.Errorf("isPrivateIP(%s) = %v, expected %v", tt.host, result, tt.expected)
+		}
+	}
+}

go_backend/extension_timeout.go

@@ -0,0 +1,118 @@
+// Package gobackend provides timeout execution for extension JS code
+package gobackend
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/dop251/goja"
+)
+
+// JSExecutionError represents an error during JS execution
+type JSExecutionError struct {
+	Message   string
+	IsTimeout bool
+}
+
+func (e *JSExecutionError) Error() string {
+	return e.Message
+}
+
+// RunWithTimeout executes JavaScript code with a timeout
+// Returns the result value and any error (including timeout)
+func RunWithTimeout(vm *goja.Runtime, script string, timeout time.Duration) (goja.Value, error) {
+	if timeout <= 0 {
+		timeout = DefaultJSTimeout
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+
+	// Channel to receive result
+	type result struct {
+		value goja.Value
+		err   error
+	}
+	resultCh := make(chan result, 1)
+
+	// Track if we've interrupted
+	var interrupted bool
+	var interruptMu sync.Mutex
+
+	// Run script in goroutine
+	go func() {
+		defer func() {
+			if r := recover(); r != nil {
+				// Check if this was our interrupt
+				interruptMu.Lock()
+				wasInterrupted := interrupted
+				interruptMu.Unlock()
+
+				if wasInterrupted {
+					resultCh <- result{nil, &JSExecutionError{
+						Message:   "execution timeout exceeded",
+						IsTimeout: true,
+					}}
+				} else {
+					resultCh <- result{nil, fmt.Errorf("panic during execution: %v", r)}
+				}
+			}
+		}()
+
+		val, err := vm.RunString(script)
+		resultCh <- result{val, err}
+	}()
+
+	// Wait for result or timeout
+	select {
+	case res := <-resultCh:
+		return res.value, res.err
+	case <-ctx.Done():
+		// Timeout - interrupt the VM
+		interruptMu.Lock()
+		interrupted = true
+		interruptMu.Unlock()
+
+		vm.Interrupt("execution timeout")
+
+		// Wait a bit for the goroutine to finish
+		select {
+		case res := <-resultCh:
+			// If we got a result after interrupt, it might be the timeout error
+			if res.err != nil {
+				return nil, res.err
+			}
+			return nil, &JSExecutionError{
+				Message:   "execution timeout exceeded",
+				IsTimeout: true,
+			}
+		case <-time.After(1 * time.Second):
+			// Force return timeout error
+			return nil, &JSExecutionError{
+				Message:   "execution timeout exceeded (force)",
+				IsTimeout: true,
+			}
+		}
+	}
+}
+
+// RunWithTimeoutAndRecover runs JS with timeout and clears interrupt state after
+// This should be used when you want to continue using the VM after a timeout
+func RunWithTimeoutAndRecover(vm *goja.Runtime, script string, timeout time.Duration) (goja.Value, error) {
+	result, err := RunWithTimeout(vm, script, timeout)
+
+	// Clear any interrupt state so VM can be reused
+	vm.ClearInterrupt()
+
+	return result, err
+}
+
+// IsTimeoutError checks if an error is a timeout error
+func IsTimeoutError(err error) bool {
+	if jsErr, ok := err.(*JSExecutionError); ok {
+		return jsErr.IsTimeout
+	}
+	return false
+}

go_backend/filename.go

@@ -6,28 +6,21 @@ import (
 	"strings"
 )
 
-// Invalid filename characters for Android/Windows/Linux
 var invalidChars = regexp.MustCompile(`[<>:"/\\|?*\x00-\x1f]`)
 
-// sanitizeFilename removes invalid characters from filename
 func sanitizeFilename(filename string) string {
-	// Replace invalid characters with underscore
 	sanitized := invalidChars.ReplaceAllString(filename, "_")
 	
-	// Remove leading/trailing spaces and dots
 	sanitized = strings.TrimSpace(sanitized)
 	sanitized = strings.Trim(sanitized, ".")
 	
-	// Collapse multiple underscores
 	multiUnderscore := regexp.MustCompile(`_+`)
 	sanitized = multiUnderscore.ReplaceAllString(sanitized, "_")
 	
-	// Limit length (Android has 255 byte limit for filenames)
 	if len(sanitized) > 200 {
 		sanitized = sanitized[:200]
 	}
 	
-	// Ensure not empty
 	if sanitized == "" {
 		sanitized = "untitled"
 	}
@@ -35,7 +28,6 @@ func sanitizeFilename(filename string) string {
 	return sanitized
 }
 
-// buildFilenameFromTemplate builds a filename from template and metadata
 func buildFilenameFromTemplate(template string, metadata map[string]interface{}) string {
 	if template == "" {
 		template = "{artist} - {title}"
@@ -43,7 +35,6 @@ func buildFilenameFromTemplate(template string, metadata map[string]interface{})
 	
 	result := template
 	
-	// Replace placeholders
 	placeholders := map[string]string{
 		"{title}":  getString(metadata, "title"),
 		"{artist}": getString(metadata, "artist"),
@@ -63,7 +54,6 @@ func buildFilenameFromTemplate(template string, metadata map[string]interface{})
 func getString(m map[string]interface{}, key string) string {
 	if v, ok := m[key]; ok {
 		if s, ok := v.(string); ok {
-			// Trim leading/trailing whitespace to prevent filename issues
 			return strings.TrimSpace(s)
 		}
 	}
@@ -98,7 +88,6 @@ func formatDiscNumber(n int) string {
 	return fmt.Sprintf("%d", n)
 }
 
-// extractYear extracts year from date string (YYYY-MM-DD or YYYY)
 func extractYear(date string) string {
 	if len(date) >= 4 {
 		return date[:4]

go_backend/go.mod

@@ -5,14 +5,19 @@ go 1.24.0
 toolchain go1.24.5
 
 require (
+	github.com/dop251/goja v0.0.0-20260106131823-651366fbe6e3
 	github.com/go-flac/flacpicture v0.3.0
 	github.com/go-flac/flacvorbis v0.2.0
 	github.com/go-flac/go-flac v1.0.0
 )
 
 require (
+	github.com/dlclark/regexp2 v1.11.4 // indirect
+	github.com/go-sourcemap/sourcemap v2.1.3+incompatible // indirect
+	github.com/google/pprof v0.0.0-20230207041349-798e818bf904 // indirect
 	golang.org/x/mobile v0.0.0-20251209145715-2553ed8ce294 // indirect
 	golang.org/x/mod v0.31.0 // indirect
 	golang.org/x/sync v0.19.0 // indirect
+	golang.org/x/text v0.3.8 // indirect
 	golang.org/x/tools v0.40.0 // indirect
 )

go_backend/go.sum

@@ -1,14 +1,28 @@
+github.com/Masterminds/semver/v3 v3.2.1 h1:RN9w6+7QoMeJVGyfmbcgs28Br8cvmnucEXnY0rYXWg0=
+github.com/Masterminds/semver/v3 v3.2.1/go.mod h1:qvl/7zhW3nngYb5+80sSMF+FG2BjYrf8m9wsX0PNOMQ=
+github.com/dlclark/regexp2 v1.11.4 h1:rPYF9/LECdNymJufQKmri9gV604RvvABwgOA8un7yAo=
+github.com/dlclark/regexp2 v1.11.4/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
+github.com/dop251/goja v0.0.0-20260106131823-651366fbe6e3 h1:bVp3yUzvSAJzu9GqID+Z96P+eu5TKnIMJSV4QaZMauM=
+github.com/dop251/goja v0.0.0-20260106131823-651366fbe6e3/go.mod h1:MxLav0peU43GgvwVgNbLAj1s/bSGboKkhuULvq/7hx4=
 github.com/go-flac/flacpicture v0.3.0 h1:LkmTxzFLIynwfhHiZsX0s8xcr3/u33MzvV89u+zOT8I=
 github.com/go-flac/flacpicture v0.3.0/go.mod h1:DPbrzVYQ3fJcvSgLFp9HXIrEQEdfdk/+m0nQCzwodZI=
 github.com/go-flac/flacvorbis v0.2.0 h1:KH0xjpkNTXFER4cszH4zeJxYcrHbUobz/RticWGOESs=
 github.com/go-flac/flacvorbis v0.2.0/go.mod h1:uIysHOtuU7OLGoCRG92bvnkg7QEqHx19qKRV6K1pBrI=
 github.com/go-flac/go-flac v1.0.0 h1:6qI9XOVLcO50xpzm3nXvO31BgDgHhnr/p/rER/K/doY=
 github.com/go-flac/go-flac v1.0.0/go.mod h1:WnZhcpmq4u1UdZMNn9LYSoASpWOCMOoxXxcWEHSzkW8=
+github.com/go-sourcemap/sourcemap v2.1.3+incompatible h1:W1iEw64niKVGogNgBN3ePyLFfuisuzeidWPMPWmECqU=
+github.com/go-sourcemap/sourcemap v2.1.3+incompatible/go.mod h1:F8jJfvm2KbVjc5NqelyYJmf/v5J0dwNLS2mL4sNA1Jg=
+github.com/google/pprof v0.0.0-20230207041349-798e818bf904 h1:4/hN5RUoecvl+RmJRE2YxKWtnnQls6rQjjW5oV7qg2U=
+github.com/google/pprof v0.0.0-20230207041349-798e818bf904/go.mod h1:uglQLonpP8qtYCYyzA+8c/9qtqgA3qsXGYqCPKARAFg=
 golang.org/x/mobile v0.0.0-20251209145715-2553ed8ce294 h1:Cr6kbEvA6nqvdHynE4CtVKlqpZB9dS1Jva/6IsHA19g=
 golang.org/x/mobile v0.0.0-20251209145715-2553ed8ce294/go.mod h1:RdZ+3sb4CVgpCFnzv+I4haEpwqFfsfzlLHs3L7ok+e0=
 golang.org/x/mod v0.31.0 h1:HaW9xtz0+kOcWKwli0ZXy79Ix+UW/vOfmWI5QVd2tgI=
 golang.org/x/mod v0.31.0/go.mod h1:43JraMp9cGx1Rx3AqioxrbrhNsLl2l/iNAvuBkrezpg=
 golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
 golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/text v0.3.8 h1:nAL+RVCQ9uMn3vJZbV+MRnydTJFPf8qqY42YiA6MrqY=
+golang.org/x/text v0.3.8/go.mod h1:E6s5w1FMmriuDzIBO73fBruAKo1PCIq6d2Q6DHfQ8WQ=
 golang.org/x/tools v0.40.0 h1:yLkxfA+Qnul4cs9QA3KnlFu0lVmd8JJfoq+E41uSutA=
 golang.org/x/tools v0.40.0/go.mod h1:Ik/tzLRlbscWpqqMRjyWYDisX8bG13FrdXp3o4Sr9lc=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

go_backend/httputil.go

@@ -1,83 +1,46 @@
 package gobackend
 
 import (
+	"crypto/tls"
+	"errors"
 	"fmt"
 	"io"
 	"math/rand"
 	"net"
 	"net/http"
+	"net/url"
 	"strconv"
+	"strings"
+	"syscall"
 	"time"
 )
 
-// HTTP utility functions for consistent request handling across all downloaders
-
 // getRandomUserAgent generates a random Windows Chrome User-Agent string
-// Uses same format as PC version (referensi/backend/spotify_metadata.go) for better API compatibility
+// Uses modern Chrome format with build and patch numbers
+// Windows 11 still reports as "Windows NT 10.0" for compatibility
 func getRandomUserAgent() string {
-	// Windows 10/11 Chrome format - same as PC version for maximum compatibility
+	// Chrome version 120-145 (modern range)
-	// Some APIs may block mobile User-Agents, so we use desktop format
+	chromeVersion := rand.Intn(26) + 120
-	winMajor := rand.Intn(2) + 10  // Windows 10 or 11
+	chromeBuild := rand.Intn(1500) + 6000
-	
+	chromePatch := rand.Intn(200) + 100
-	chromeVersion := rand.Intn(25) + 100 // Chrome 100-124
+
-	chromeBuild := rand.Intn(1500) + 3000 // Build 3000-4500
-	chromePatch := rand.Intn(65) + 60 // Patch 60-125
-	
 	return fmt.Sprintf(
-		"Mozilla/5.0 (Windows NT %d.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%d.0.%d.%d Safari/537.36",
+		"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/%d.0.%d.%d Safari/537.36",
-		winMajor,
 		chromeVersion,
 		chromeBuild,
 		chromePatch,
 	)
 }
 
-// getRandomMacUserAgent generates a random Mac Chrome User-Agent string
-// Alternative format matching referensi/backend/spotify_metadata.go exactly
-func getRandomMacUserAgent() string {
-	macMajor := rand.Intn(4) + 11  // macOS 11-14
-	macMinor := rand.Intn(5) + 4   // Minor 4-8
-	webkitMajor := rand.Intn(7) + 530
-	webkitMinor := rand.Intn(7) + 30
-	chromeMajor := rand.Intn(25) + 80
-	chromeBuild := rand.Intn(1500) + 3000
-	chromePatch := rand.Intn(65) + 60
-	safariMajor := rand.Intn(7) + 530
-	safariMinor := rand.Intn(6) + 30
-
-	return fmt.Sprintf(
-		"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_%d_%d) AppleWebKit/%d.%d (KHTML, like Gecko) Chrome/%d.0.%d.%d Safari/%d.%d",
-		macMajor,
-		macMinor,
-		webkitMajor,
-		webkitMinor,
-		chromeMajor,
-		chromeBuild,
-		chromePatch,
-		safariMajor,
-		safariMinor,
-	)
-}
-
-// getRandomDesktopUserAgent randomly picks between Windows and Mac User-Agent
-func getRandomDesktopUserAgent() string {
-	if rand.Intn(2) == 0 {
-		return getRandomUserAgent() // Windows
-	}
-	return getRandomMacUserAgent() // Mac
-}
-
-// Default timeout values
 const (
-	DefaultTimeout     = 60 * time.Second  // Default HTTP timeout
+	DefaultTimeout    = 60 * time.Second
-	DownloadTimeout    = 120 * time.Second // Timeout for file downloads
+	DownloadTimeout   = 120 * time.Second
-	SongLinkTimeout    = 30 * time.Second  // Timeout for SongLink API
+	SongLinkTimeout   = 30 * time.Second
-	DefaultMaxRetries  = 3                 // Default retry count
+	DefaultMaxRetries = 3
-	DefaultRetryDelay  = 1 * time.Second   // Initial retry delay
+	DefaultRetryDelay = 1 * time.Second
 )
 
 // Shared transport with connection pooling to prevent TCP exhaustion
-// Optimized for large file downloads (FLAC ~30-50MB)
 var sharedTransport = &http.Transport{
 	DialContext: (&net.Dialer{
 		Timeout:   30 * time.Second,
@@ -89,27 +52,23 @@ var sharedTransport = &http.Transport{
 	IdleConnTimeout:       90 * time.Second,
 	TLSHandshakeTimeout:   10 * time.Second,
 	ExpectContinueTimeout: 1 * time.Second,
-	DisableKeepAlives:     false, // Enable keep-alives for connection reuse
+	DisableKeepAlives:     false,
 	ForceAttemptHTTP2:     true,
-	WriteBufferSize:       64 * 1024,  // 64KB write buffer
+	WriteBufferSize:       64 * 1024,
-	ReadBufferSize:        64 * 1024,  // 64KB read buffer
+	ReadBufferSize:        64 * 1024,
-	DisableCompression:    true,       // FLAC is already compressed
+	DisableCompression:    true,
 }
 
-// Shared HTTP client for general requests (reuses connections)
 var sharedClient = &http.Client{
 	Transport: sharedTransport,
 	Timeout:   DefaultTimeout,
 }
 
-// Shared HTTP client for downloads (longer timeout, reuses connections)
 var downloadClient = &http.Client{
 	Transport: sharedTransport,
 	Timeout:   DownloadTimeout,
 }
 
-// NewHTTPClientWithTimeout creates an HTTP client with specified timeout
-// Uses shared transport for connection reuse
 func NewHTTPClientWithTimeout(timeout time.Duration) *http.Client {
 	return &http.Client{
 		Transport: sharedTransport,
@@ -117,26 +76,27 @@ func NewHTTPClientWithTimeout(timeout time.Duration) *http.Client {
 	}
 }
 
-// GetSharedClient returns the shared HTTP client for general requests
 func GetSharedClient() *http.Client {
 	return sharedClient
 }
 
-// GetDownloadClient returns the shared HTTP client for downloads
 func GetDownloadClient() *http.Client {
 	return downloadClient
 }
 
 // CloseIdleConnections closes idle connections in the shared transport
-// Call this periodically during large batch downloads to prevent connection buildup
 func CloseIdleConnections() {
 	sharedTransport.CloseIdleConnections()
 }
 
-// DoRequestWithUserAgent executes an HTTP request with a random User-Agent header
+// Also checks for ISP blocking on errors
 func DoRequestWithUserAgent(client *http.Client, req *http.Request) (*http.Response, error) {
 	req.Header.Set("User-Agent", getRandomUserAgent())
-	return client.Do(req)
+	resp, err := client.Do(req)
+	if err != nil {
+		CheckAndLogISPBlocking(err, req.URL.String(), "HTTP")
+	}
+	return resp, err
 }
 
 // RetryConfig holds configuration for retry logic
@@ -147,7 +107,6 @@ type RetryConfig struct {
 	BackoffFactor float64
 }
 
-// DefaultRetryConfig returns default retry configuration
 func DefaultRetryConfig() RetryConfig {
 	return RetryConfig{
 		MaxRetries:    DefaultMaxRetries,
@@ -159,9 +118,11 @@ func DefaultRetryConfig() RetryConfig {
 
 // DoRequestWithRetry executes an HTTP request with retry logic and exponential backoff
 // Handles 429 (Too Many Requests) responses with Retry-After header
+// Also detects and logs ISP blocking
 func DoRequestWithRetry(client *http.Client, req *http.Request, config RetryConfig) (*http.Response, error) {
 	var lastErr error
 	delay := config.InitialDelay
+	requestURL := req.URL.String()
 
 	for attempt := 0; attempt <= config.MaxRetries; attempt++ {
 		// Clone request for retry (body needs to be re-readable)
@@ -171,7 +132,16 @@ func DoRequestWithRetry(client *http.Client, req *http.Request, config RetryConf
 		resp, err := client.Do(reqCopy)
 		if err != nil {
 			lastErr = err
+
+			// Check for ISP blocking on network errors
+			if CheckAndLogISPBlocking(err, requestURL, "HTTP") {
+				// Don't retry if ISP blocking is detected - it won't help
+				return nil, WrapErrorWithISPCheck(err, requestURL, "HTTP")
+			}
+
 			if attempt < config.MaxRetries {
+				GoLog("[HTTP] Request failed (attempt %d/%d): %v, retrying in %v...\n",
+					attempt+1, config.MaxRetries+1, err, delay)
 				time.Sleep(delay)
 				delay = calculateNextDelay(delay, config)
 			}
@@ -192,17 +162,43 @@ func DoRequestWithRetry(client *http.Client, req *http.Request, config RetryConf
 			}
 			lastErr = fmt.Errorf("rate limited (429)")
 			if attempt < config.MaxRetries {
+				GoLog("[HTTP] Rate limited, waiting %v before retry...\n", delay)
 				time.Sleep(delay)
 				delay = calculateNextDelay(delay, config)
 			}
 			continue
 		}
 
+		// Check for ISP blocking via HTTP status codes
+		// Some ISPs return 403 or 451 when blocking content
+		if resp.StatusCode == 403 || resp.StatusCode == 451 {
+			body, _ := io.ReadAll(resp.Body)
+			resp.Body.Close()
+			bodyStr := strings.ToLower(string(body))
+
+			// Check if response looks like ISP blocking page
+			ispBlockingIndicators := []string{
+				"blocked", "forbidden", "access denied", "not available in your",
+				"restricted", "censored", "unavailable for legal", "blocked by",
+			}
+
+			for _, indicator := range ispBlockingIndicators {
+				if strings.Contains(bodyStr, indicator) {
+					LogError("HTTP", "ISP BLOCKING DETECTED via HTTP %d response", resp.StatusCode)
+					LogError("HTTP", "Domain: %s", req.URL.Host)
+					LogError("HTTP", "Response contains: %s", indicator)
+					LogError("HTTP", "Suggestion: Try using a VPN or changing your DNS to 1.1.1.1 or 8.8.8.8")
+					return nil, fmt.Errorf("ISP blocking detected for %s (HTTP %d) - try using VPN or change DNS", req.URL.Host, resp.StatusCode)
+				}
+			}
+		}
+
 		// Server errors (5xx) - retry
 		if resp.StatusCode >= 500 {
 			resp.Body.Close()
 			lastErr = fmt.Errorf("server error: HTTP %d", resp.StatusCode)
 			if attempt < config.MaxRetries {
+				GoLog("[HTTP] Server error %d, retrying in %v...\n", resp.StatusCode, delay)
 				time.Sleep(delay)
 				delay = calculateNextDelay(delay, config)
 			}
@@ -216,16 +212,11 @@ func DoRequestWithRetry(client *http.Client, req *http.Request, config RetryConf
 	return nil, fmt.Errorf("request failed after %d retries: %w", config.MaxRetries+1, lastErr)
 }
 
-// calculateNextDelay calculates the next delay with exponential backoff
 func calculateNextDelay(currentDelay time.Duration, config RetryConfig) time.Duration {
 	nextDelay := time.Duration(float64(currentDelay) * config.BackoffFactor)
-	if nextDelay > config.MaxDelay {
+	return min(nextDelay, config.MaxDelay)
-		nextDelay = config.MaxDelay
-	}
-	return nextDelay
 }
 
-// getRetryAfterDuration parses Retry-After header and returns duration
 // Returns 60 seconds as default if header is missing or invalid
 func getRetryAfterDuration(resp *http.Response) time.Duration {
 	retryAfter := resp.Header.Get("Retry-After")
@@ -268,7 +259,6 @@ func ReadResponseBody(resp *http.Response) ([]byte, error) {
 	return body, nil
 }
 
-// ValidateResponse checks if response is valid (non-nil, status 2xx)
 func ValidateResponse(resp *http.Response) error {
 	if resp == nil {
 		return fmt.Errorf("response is nil")
@@ -296,3 +286,169 @@ func BuildErrorMessage(apiURL string, statusCode int, responsePreview string) st
 	}
 	return msg
 }
+
+type ISPBlockingError struct {
+	Domain      string
+	Reason      string
+	OriginalErr error
+}
+
+func (e *ISPBlockingError) Error() string {
+	return fmt.Sprintf("ISP blocking detected for %s: %s", e.Domain, e.Reason)
+}
+
+// IsISPBlocking checks if an error is likely caused by ISP blocking
+// Returns the ISPBlockingError if detected, nil otherwise
+func IsISPBlocking(err error, requestURL string) *ISPBlockingError {
+	if err == nil {
+		return nil
+	}
+
+	// Extract domain from URL
+	domain := extractDomain(requestURL)
+	errStr := strings.ToLower(err.Error())
+
+	// Check for DNS resolution failure (common ISP blocking method)
+	var dnsErr *net.DNSError
+	if errors.As(err, &dnsErr) {
+		if dnsErr.IsNotFound || dnsErr.IsTemporary {
+			return &ISPBlockingError{
+				Domain:      domain,
+				Reason:      "DNS resolution failed - domain may be blocked by ISP",
+				OriginalErr: err,
+			}
+		}
+	}
+
+	// Check for connection refused (ISP firewall blocking)
+	var opErr *net.OpError
+	if errors.As(err, &opErr) {
+		if opErr.Op == "dial" {
+			// Check for specific syscall errors
+			var syscallErr syscall.Errno
+			if errors.As(opErr.Err, &syscallErr) {
+				switch syscallErr {
+				case syscall.ECONNREFUSED:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Connection refused - port may be blocked by ISP/firewall",
+						OriginalErr: err,
+					}
+				case syscall.ECONNRESET:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Connection reset - ISP may be intercepting traffic",
+						OriginalErr: err,
+					}
+				case syscall.ETIMEDOUT:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Connection timed out - ISP may be blocking access",
+						OriginalErr: err,
+					}
+				case syscall.ENETUNREACH:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Network unreachable - ISP may be blocking route",
+						OriginalErr: err,
+					}
+				case syscall.EHOSTUNREACH:
+					return &ISPBlockingError{
+						Domain:      domain,
+						Reason:      "Host unreachable - ISP may be blocking destination",
+						OriginalErr: err,
+					}
+				}
+			}
+		}
+	}
+
+	// Check for TLS handshake failure (ISP MITM or blocking HTTPS)
+	var tlsErr *tls.RecordHeaderError
+	if errors.As(err, &tlsErr) {
+		return &ISPBlockingError{
+			Domain:      domain,
+			Reason:      "TLS handshake failed - ISP may be intercepting HTTPS traffic",
+			OriginalErr: err,
+		}
+	}
+
+	// Check error message patterns for common ISP blocking indicators
+	blockingPatterns := []struct {
+		pattern string
+		reason  string
+	}{
+		{"connection reset by peer", "Connection reset - ISP may be intercepting traffic"},
+		{"connection refused", "Connection refused - port may be blocked"},
+		{"no such host", "DNS lookup failed - domain may be blocked by ISP"},
+		{"i/o timeout", "Connection timed out - ISP may be blocking access"},
+		{"network is unreachable", "Network unreachable - ISP may be blocking route"},
+		{"tls: ", "TLS error - ISP may be intercepting HTTPS traffic"},
+		{"certificate", "Certificate error - ISP may be using MITM proxy"},
+		{"eof", "Connection closed unexpectedly - ISP may be blocking"},
+		{"context deadline exceeded", "Request timed out - ISP may be throttling"},
+	}
+
+	for _, bp := range blockingPatterns {
+		if strings.Contains(errStr, bp.pattern) {
+			return &ISPBlockingError{
+				Domain:      domain,
+				Reason:      bp.reason,
+				OriginalErr: err,
+			}
+		}
+	}
+
+	return nil
+}
+
+// Returns true if ISP blocking was detected
+func CheckAndLogISPBlocking(err error, requestURL string, tag string) bool {
+	ispErr := IsISPBlocking(err, requestURL)
+	if ispErr != nil {
+		LogError(tag, "ISP BLOCKING DETECTED: %s", ispErr.Error())
+		LogError(tag, "Domain: %s", ispErr.Domain)
+		LogError(tag, "Reason: %s", ispErr.Reason)
+		LogError(tag, "Original error: %v", ispErr.OriginalErr)
+		LogError(tag, "Suggestion: Try using a VPN or changing your DNS to 1.1.1.1 or 8.8.8.8")
+		return true
+	}
+	return false
+}
+
+// extractDomain extracts the domain from a URL string
+func extractDomain(rawURL string) string {
+	if rawURL == "" {
+		return "unknown"
+	}
+
+	parsed, err := url.Parse(rawURL)
+	if err != nil {
+		// Try to extract domain manually
+		rawURL = strings.TrimPrefix(rawURL, "https://")
+		rawURL = strings.TrimPrefix(rawURL, "http://")
+		if idx := strings.Index(rawURL, "/"); idx > 0 {
+			return rawURL[:idx]
+		}
+		return rawURL
+	}
+
+	if parsed.Host != "" {
+		return parsed.Host
+	}
+	return "unknown"
+}
+
+// If ISP blocking is detected, returns a more descriptive error
+func WrapErrorWithISPCheck(err error, requestURL string, tag string) error {
+	if err == nil {
+		return nil
+	}
+
+	if CheckAndLogISPBlocking(err, requestURL, tag) {
+		domain := extractDomain(requestURL)
+		return fmt.Errorf("ISP blocking detected for %s - try using VPN or change DNS to 1.1.1.1/8.8.8.8: %w", domain, err)
+	}
+
+	return err
+}

go_backend/logbuffer.go

@@ -0,0 +1,195 @@
+package gobackend
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+)
+
+type LogEntry struct {
+	Timestamp string `json:"timestamp"`
+	Level     string `json:"level"`
+	Tag       string `json:"tag"`
+	Message   string `json:"message"`
+}
+
+type LogBuffer struct {
+	entries        []LogEntry
+	maxSize        int
+	mu             sync.RWMutex
+	loggingEnabled bool
+}
+
+var (
+	globalLogBuffer *LogBuffer
+	logBufferOnce   sync.Once
+)
+
+// GetLogBuffer returns the singleton log buffer instance
+func GetLogBuffer() *LogBuffer {
+	logBufferOnce.Do(func() {
+		globalLogBuffer = &LogBuffer{
+			entries:        make([]LogEntry, 0, 1000),
+			maxSize:        1000,
+			loggingEnabled: false, // Default: disabled for performance (user can enable in settings)
+		}
+	})
+	return globalLogBuffer
+}
+
+func (lb *LogBuffer) SetLoggingEnabled(enabled bool) {
+	lb.mu.Lock()
+	defer lb.mu.Unlock()
+	lb.loggingEnabled = enabled
+}
+
+// IsLoggingEnabled returns whether logging is enabled
+func (lb *LogBuffer) IsLoggingEnabled() bool {
+	lb.mu.RLock()
+	defer lb.mu.RUnlock()
+	return lb.loggingEnabled
+}
+
+func (lb *LogBuffer) Add(level, tag, message string) {
+	lb.mu.Lock()
+	defer lb.mu.Unlock()
+
+	if !lb.loggingEnabled && level != "ERROR" && level != "FATAL" {
+		return
+	}
+
+	entry := LogEntry{
+		Timestamp: time.Now().Format("15:04:05.000"),
+		Level:     level,
+		Tag:       tag,
+		Message:   message,
+	}
+
+	if len(lb.entries) >= lb.maxSize {
+		lb.entries = lb.entries[1:]
+	}
+	lb.entries = append(lb.entries, entry)
+
+	fmt.Printf("[%s] %s\n", tag, message)
+}
+
+// GetAll returns all log entries as JSON
+func (lb *LogBuffer) GetAll() string {
+	lb.mu.RLock()
+	defer lb.mu.RUnlock()
+
+	jsonBytes, _ := json.Marshal(lb.entries)
+	return string(jsonBytes)
+}
+
+func (lb *LogBuffer) getSince(index int) ([]LogEntry, int) {
+	lb.mu.RLock()
+	defer lb.mu.RUnlock()
+
+	if index < 0 {
+		index = 0
+	}
+	if index >= len(lb.entries) {
+		return []LogEntry{}, len(lb.entries)
+	}
+
+	entries := lb.entries[index:]
+	return entries, len(lb.entries)
+}
+
+// Clear clears all log entries
+func (lb *LogBuffer) Clear() {
+	lb.mu.Lock()
+	defer lb.mu.Unlock()
+	lb.entries = lb.entries[:0]
+}
+
+// Count returns the number of log entries
+func (lb *LogBuffer) Count() int {
+	lb.mu.RLock()
+	defer lb.mu.RUnlock()
+	return len(lb.entries)
+}
+
+// Helper functions for logging with different levels
+func LogDebug(tag, format string, args ...interface{}) {
+	GetLogBuffer().Add("DEBUG", tag, fmt.Sprintf(format, args...))
+}
+
+func LogInfo(tag, format string, args ...interface{}) {
+	GetLogBuffer().Add("INFO", tag, fmt.Sprintf(format, args...))
+}
+
+func LogWarn(tag, format string, args ...interface{}) {
+	GetLogBuffer().Add("WARN", tag, fmt.Sprintf(format, args...))
+}
+
+func LogError(tag, format string, args ...interface{}) {
+	GetLogBuffer().Add("ERROR", tag, fmt.Sprintf(format, args...))
+}
+
+// GoLog is a drop-in replacement for fmt.Printf that also logs to buffer
+// It parses the tag from the format string if it starts with [Tag]
+func GoLog(format string, args ...interface{}) {
+	message := fmt.Sprintf(format, args...)
+	message = strings.TrimSuffix(message, "\n")
+
+	// Extract tag from message if present (e.g., "[Tidal] message")
+	tag := "Go"
+	level := "INFO"
+
+	if strings.HasPrefix(message, "[") {
+		endBracket := strings.Index(message, "]")
+		if endBracket > 1 {
+			tag = message[1:endBracket]
+			message = strings.TrimSpace(message[endBracket+1:])
+		}
+	}
+
+	// Determine level from message content
+	msgLower := strings.ToLower(message)
+	if strings.Contains(msgLower, "error") || strings.Contains(msgLower, "failed") || strings.HasPrefix(message, "✗") {
+		level = "ERROR"
+	} else if strings.Contains(msgLower, "warning") || strings.Contains(msgLower, "warn") {
+		level = "WARN"
+	} else if strings.HasPrefix(message, "✓") || strings.Contains(msgLower, "success") || strings.Contains(msgLower, "match found") {
+		level = "INFO"
+	} else if strings.Contains(msgLower, "searching") || strings.Contains(msgLower, "trying") || strings.Contains(msgLower, "found") {
+		level = "DEBUG"
+	}
+
+	GetLogBuffer().Add(level, tag, message)
+}
+
+// Exported functions for Flutter
+
+// GetLogs returns all logs as JSON array
+func GetLogs() string {
+	return GetLogBuffer().GetAll()
+}
+
+// GetLogsSince returns logs since the given index
+// Returns JSON: {"logs": [...], "next_index": N}
+func GetLogsSince(index int) string {
+	entries, nextIndex := GetLogBuffer().getSince(index)
+	logsJson, _ := json.Marshal(entries)
+	result := fmt.Sprintf(`{"logs":%s,"next_index":%d}`, string(logsJson), nextIndex)
+	return result
+}
+
+// ClearLogs clears all logs
+func ClearLogs() {
+	GetLogBuffer().Clear()
+}
+
+// GetLogCount returns the number of log entries
+func GetLogCount() int {
+	return GetLogBuffer().Count()
+}
+
+// SetLoggingEnabled enables or disables logging from Flutter
+func SetLoggingEnabled(enabled bool) {
+	GetLogBuffer().SetLoggingEnabled(enabled)
+}

go_backend/lyrics.go

@@ -3,14 +3,93 @@ package gobackend
 import (
 	"encoding/json"
 	"fmt"
+	"math"
 	"net/http"
 	"net/url"
+	"os"
+	"path/filepath"
 	"regexp"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 )
 
+const (
+	lyricsCacheTTL       = 24 * time.Hour
+	durationToleranceSec = 10.0
+)
+
+type lyricsCacheEntry struct {
+	response  *LyricsResponse
+	expiresAt time.Time
+}
+
+type lyricsCache struct {
+	mu    sync.RWMutex
+	cache map[string]*lyricsCacheEntry
+}
+
+var globalLyricsCache = &lyricsCache{
+	cache: make(map[string]*lyricsCacheEntry),
+}
+
+func (c *lyricsCache) generateKey(artist, track string, durationSec float64) string {
+	normalizedArtist := strings.ToLower(strings.TrimSpace(artist))
+	normalizedTrack := strings.ToLower(strings.TrimSpace(track))
+	roundedDuration := math.Round(durationSec/10) * 10
+	return fmt.Sprintf("%s|%s|%.0f", normalizedArtist, normalizedTrack, roundedDuration)
+}
+
+func (c *lyricsCache) Get(artist, track string, durationSec float64) (*LyricsResponse, bool) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	key := c.generateKey(artist, track, durationSec)
+	entry, exists := c.cache[key]
+	if !exists {
+		return nil, false
+	}
+
+	if time.Now().After(entry.expiresAt) {
+		return nil, false
+	}
+
+	return entry.response, true
+}
+
+func (c *lyricsCache) Set(artist, track string, durationSec float64, response *LyricsResponse) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	key := c.generateKey(artist, track, durationSec)
+	c.cache[key] = &lyricsCacheEntry{
+		response:  response,
+		expiresAt: time.Now().Add(lyricsCacheTTL),
+	}
+}
+
+func (c *lyricsCache) CleanExpired() int {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	now := time.Now()
+	cleaned := 0
+	for key, entry := range c.cache {
+		if now.After(entry.expiresAt) {
+			delete(c.cache, key)
+			cleaned++
+		}
+	}
+	return cleaned
+}
+
+func (c *lyricsCache) Size() int {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	return len(c.cache)
+}
+
 type LRCLibResponse struct {
 	ID           int     `json:"id"`
 	Name         string  `json:"name"`
@@ -44,9 +123,7 @@ type LyricsClient struct {
 
 func NewLyricsClient() *LyricsClient {
 	return &LyricsClient{
-		httpClient: &http.Client{
+		httpClient: NewHTTPClientWithTimeout(15 * time.Second),
-			Timeout: 15 * time.Second,
-		},
 	}
 }
 
@@ -86,7 +163,7 @@ func (c *LyricsClient) FetchLyricsWithMetadata(artist, track string) (*LyricsRes
 	return c.parseLRCLibResponse(&lrcResp), nil
 }
 
-func (c *LyricsClient) FetchLyricsFromLRCLibSearch(query string) (*LyricsResponse, error) {
+func (c *LyricsClient) FetchLyricsFromLRCLibSearch(query string, durationSec float64) (*LyricsResponse, error) {
 	baseURL := "https://lrclib.net/api/search"
 	params := url.Values{}
 	params.Set("q", query)
@@ -118,6 +195,11 @@ func (c *LyricsClient) FetchLyricsFromLRCLibSearch(query string) (*LyricsRespons
 		return nil, fmt.Errorf("no lyrics found")
 	}
 
+	bestMatch := c.findBestMatch(results, durationSec)
+	if bestMatch != nil {
+		return c.parseLRCLibResponse(bestMatch), nil
+	}
+
 	for _, result := range results {
 		if result.SyncedLyrics != "" {
 			return c.parseLRCLibResponse(&result), nil
@@ -127,38 +209,83 @@ func (c *LyricsClient) FetchLyricsFromLRCLibSearch(query string) (*LyricsRespons
 	return c.parseLRCLibResponse(&results[0]), nil
 }
 
-func (c *LyricsClient) FetchLyricsAllSources(spotifyID, trackName, artistName string) (*LyricsResponse, error) {
+func (c *LyricsClient) findBestMatch(results []LRCLibResponse, targetDurationSec float64) *LRCLibResponse {
-	// Strategy 1: Direct match with artist and track name
+	var bestSynced *LRCLibResponse
-	lyrics, err := c.FetchLyricsWithMetadata(artistName, trackName)
+	var bestPlain *LRCLibResponse
+
+	for i := range results {
+		result := &results[i]
+
+		durationMatches := targetDurationSec == 0 || c.durationMatches(result.Duration, targetDurationSec)
+
+		if durationMatches {
+			if result.SyncedLyrics != "" && bestSynced == nil {
+				bestSynced = result
+			} else if result.PlainLyrics != "" && bestPlain == nil {
+				bestPlain = result
+			}
+		}
+	}
+
+	if bestSynced != nil {
+		return bestSynced
+	}
+	return bestPlain
+}
+
+func (c *LyricsClient) durationMatches(lrcDuration, targetDuration float64) bool {
+	diff := math.Abs(lrcDuration - targetDuration)
+	return diff <= durationToleranceSec
+}
+
+// durationSec: track duration in seconds for matching, use 0 to skip duration matching
+func (c *LyricsClient) FetchLyricsAllSources(spotifyID, trackName, artistName string, durationSec float64) (*LyricsResponse, error) {
+	// Check cache first
+	if cached, found := globalLyricsCache.Get(artistName, trackName, durationSec); found {
+		fmt.Printf("[Lyrics] Cache hit for: %s - %s\n", artistName, trackName)
+		cachedCopy := *cached
+		cachedCopy.Source = cached.Source + " (cached)"
+		return &cachedCopy, nil
+	}
+
+	var lyrics *LyricsResponse
+	var err error
+
+	// Try exact match first
+	lyrics, err = c.FetchLyricsWithMetadata(artistName, trackName)
 	if err == nil && lyrics != nil && len(lyrics.Lines) > 0 {
 		lyrics.Source = "LRCLIB"
+		globalLyricsCache.Set(artistName, trackName, durationSec, lyrics)
 		return lyrics, nil
 	}
 
-	// Strategy 2: Try with simplified track name
+	// Try with simplified track name
 	simplifiedTrack := simplifyTrackName(trackName)
 	if simplifiedTrack != trackName {
 		lyrics, err = c.FetchLyricsWithMetadata(artistName, simplifiedTrack)
 		if err == nil && lyrics != nil && len(lyrics.Lines) > 0 {
 			lyrics.Source = "LRCLIB (simplified)"
+			globalLyricsCache.Set(artistName, trackName, durationSec, lyrics)
 			return lyrics, nil
 		}
 	}
 
-	// Strategy 3: Search with full query
+	// Search with duration matching
 	query := artistName + " " + trackName
-	lyrics, err = c.FetchLyricsFromLRCLibSearch(query)
+	lyrics, err = c.FetchLyricsFromLRCLibSearch(query, durationSec)
 	if err == nil && lyrics != nil && len(lyrics.Lines) > 0 {
 		lyrics.Source = "LRCLIB Search"
+		globalLyricsCache.Set(artistName, trackName, durationSec, lyrics)
 		return lyrics, nil
 	}
 
-	// Strategy 4: Search with simplified query
+	// Search with simplified name and duration matching
 	if simplifiedTrack != trackName {
 		query = artistName + " " + simplifiedTrack
-		lyrics, err = c.FetchLyricsFromLRCLibSearch(query)
+		lyrics, err = c.FetchLyricsFromLRCLibSearch(query, durationSec)
 		if err == nil && lyrics != nil && len(lyrics.Lines) > 0 {
 			lyrics.Source = "LRCLIB Search (simplified)"
+			globalLyricsCache.Set(artistName, trackName, durationSec, lyrics)
 			return lyrics, nil
 		}
 	}
@@ -248,34 +375,32 @@ func msToLRCTimestamp(ms int64) string {
 	return fmt.Sprintf("[%02d:%02d.%02d]", minutes, seconds, centiseconds)
 }
 
-// convertToLRC converts lyrics to LRC format string (without metadata headers)
 // Use convertToLRCWithMetadata for full LRC with headers
-func convertToLRC(lyrics *LyricsResponse) string {
+// Kept for potential future use
-	if lyrics == nil || len(lyrics.Lines) == 0 {
+// func convertToLRC(lyrics *LyricsResponse) string {
-		return ""
+// 	if lyrics == nil || len(lyrics.Lines) == 0 {
-	}
+// 		return ""
+// 	}
+//
+// 	var builder strings.Builder
+//
+// 	if lyrics.SyncType == "LINE_SYNCED" {
+// 		for _, line := range lyrics.Lines {
+// 			timestamp := msToLRCTimestamp(line.StartTimeMs)
+// 			builder.WriteString(timestamp)
+// 			builder.WriteString(line.Words)
+// 			builder.WriteString("\n")
+// 		}
+// 	} else {
+// 		for _, line := range lyrics.Lines {
+// 			builder.WriteString(line.Words)
+// 			builder.WriteString("\n")
+// 		}
+// 	}
+//
+// 	return builder.String()
+// }
 
-	var builder strings.Builder
-
-	if lyrics.SyncType == "LINE_SYNCED" {
-		for _, line := range lyrics.Lines {
-			timestamp := msToLRCTimestamp(line.StartTimeMs)
-			builder.WriteString(timestamp)
-			builder.WriteString(line.Words)
-			builder.WriteString("\n")
-		}
-	} else {
-		for _, line := range lyrics.Lines {
-			builder.WriteString(line.Words)
-			builder.WriteString("\n")
-		}
-	}
-
-	return builder.String()
-}
-
-// convertToLRCWithMetadata converts lyrics to LRC format with metadata headers
-// Includes [ti:], [ar:], [by:] headers
 func convertToLRCWithMetadata(lyrics *LyricsResponse, trackName, artistName string) string {
 	if lyrics == nil || len(lyrics.Lines) == 0 {
 		return ""
@@ -283,13 +408,11 @@ func convertToLRCWithMetadata(lyrics *LyricsResponse, trackName, artistName stri
 
 	var builder strings.Builder
 
-	// Add metadata headers
 	builder.WriteString(fmt.Sprintf("[ti:%s]\n", trackName))
 	builder.WriteString(fmt.Sprintf("[ar:%s]\n", artistName))
 	builder.WriteString("[by:SpotiFLAC-Mobile]\n")
 	builder.WriteString("\n")
 
-	// Add lyrics lines
 	if lyrics.SyncType == "LINE_SYNCED" {
 		for _, line := range lyrics.Lines {
 			if line.Words == "" {
@@ -338,3 +461,22 @@ func simplifyTrackName(name string) string {
 
 	return strings.TrimSpace(result)
 }
+
+func SaveLRCFile(audioFilePath, lrcContent string) (string, error) {
+	if lrcContent == "" {
+		return "", fmt.Errorf("empty LRC content")
+	}
+
+	dir := filepath.Dir(audioFilePath)
+	ext := filepath.Ext(audioFilePath)
+	baseName := strings.TrimSuffix(filepath.Base(audioFilePath), ext)
+
+	lrcFilePath := filepath.Join(dir, baseName+".lrc")
+
+	if err := os.WriteFile(lrcFilePath, []byte(lrcContent), 0644); err != nil {
+		return "", fmt.Errorf("failed to write LRC file: %w", err)
+	}
+
+	GoLog("[Lyrics] Saved LRC file: %s\n", lrcFilePath)
+	return lrcFilePath, nil
+}

go_backend/parallel.go

@@ -6,11 +6,6 @@ import (
 	"time"
 )
 
-// ========================================
-// ISRC to Track ID Cache
-// ========================================
-
-// TrackIDCacheEntry holds cached track ID with metadata
 type TrackIDCacheEntry struct {
 	TidalTrackID  int64
 	QobuzTrackID  int64
@@ -18,7 +13,6 @@ type TrackIDCacheEntry struct {
 	ExpiresAt     time.Time
 }
 
-// TrackIDCache caches ISRC to track ID mappings
 type TrackIDCache struct {
 	cache map[string]*TrackIDCacheEntry
 	mu    sync.RWMutex
@@ -30,18 +24,16 @@ var (
 	trackIDCacheOnce   sync.Once
 )
 
-// GetTrackIDCache returns the global track ID cache
 func GetTrackIDCache() *TrackIDCache {
 	trackIDCacheOnce.Do(func() {
 		globalTrackIDCache = &TrackIDCache{
 			cache: make(map[string]*TrackIDCacheEntry),
-			ttl:   30 * time.Minute, // Cache for 30 minutes
+			ttl:   30 * time.Minute,
 		}
 	})
 	return globalTrackIDCache
 }
 
-// Get retrieves a cached entry by ISRC
 func (c *TrackIDCache) Get(isrc string) *TrackIDCacheEntry {
 	c.mu.RLock()
 	defer c.mu.RUnlock()
@@ -53,7 +45,6 @@ func (c *TrackIDCache) Get(isrc string) *TrackIDCacheEntry {
 	return entry
 }
 
-// SetTidal caches Tidal track ID for an ISRC
 func (c *TrackIDCache) SetTidal(isrc string, trackID int64) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
@@ -67,7 +58,6 @@ func (c *TrackIDCache) SetTidal(isrc string, trackID int64) {
 	entry.ExpiresAt = time.Now().Add(c.ttl)
 }
 
-// SetQobuz caches Qobuz track ID for an ISRC
 func (c *TrackIDCache) SetQobuz(isrc string, trackID int64) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
@@ -81,7 +71,6 @@ func (c *TrackIDCache) SetQobuz(isrc string, trackID int64) {
 	entry.ExpiresAt = time.Now().Add(c.ttl)
 }
 
-// SetAmazon caches Amazon track ID for an ISRC
 func (c *TrackIDCache) SetAmazon(isrc string, trackID string) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
@@ -95,24 +84,18 @@ func (c *TrackIDCache) SetAmazon(isrc string, trackID string) {
 	entry.ExpiresAt = time.Now().Add(c.ttl)
 }
 
-// Clear removes all cached entries
 func (c *TrackIDCache) Clear() {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 	c.cache = make(map[string]*TrackIDCacheEntry)
 }
 
-// Size returns the number of cached entries
 func (c *TrackIDCache) Size() int {
 	c.mu.RLock()
 	defer c.mu.RUnlock()
 	return len(c.cache)
 }
 
-// ========================================
-// Parallel Download Helper
-// ========================================
-
 // ParallelDownloadResult holds results from parallel operations
 type ParallelDownloadResult struct {
 	CoverData  []byte
@@ -122,8 +105,6 @@ type ParallelDownloadResult struct {
 	LyricsErr  error
 }
 
-// FetchCoverAndLyricsParallel downloads cover and fetches lyrics in parallel
-// This runs while the main audio download is happening
 func FetchCoverAndLyricsParallel(
 	coverURL string,
 	maxQualityCover bool,
@@ -131,11 +112,11 @@ func FetchCoverAndLyricsParallel(
 	trackName string,
 	artistName string,
 	embedLyrics bool,
+	durationMs int64,
 ) *ParallelDownloadResult {
 	result := &ParallelDownloadResult{}
 	var wg sync.WaitGroup
 
-	// Download cover in parallel
 	if coverURL != "" {
 		wg.Add(1)
 		go func() {
@@ -152,20 +133,19 @@ func FetchCoverAndLyricsParallel(
 		}()
 	}
 
-	// Fetch lyrics in parallel
 	if embedLyrics {
 		wg.Add(1)
 		go func() {
 			defer wg.Done()
 			fmt.Println("[Parallel] Starting lyrics fetch...")
 			client := NewLyricsClient()
-			lyrics, err := client.FetchLyricsAllSources(spotifyID, trackName, artistName)
+			durationSec := float64(durationMs) / 1000.0
+			lyrics, err := client.FetchLyricsAllSources(spotifyID, trackName, artistName, durationSec)
 			if err != nil {
 				result.LyricsErr = err
 				fmt.Printf("[Parallel] Lyrics fetch failed: %v\n", err)
 			} else if lyrics != nil && len(lyrics.Lines) > 0 {
 				result.LyricsData = lyrics
-				// Use LRC with metadata headers (like PC version)
 				result.LyricsLRC = convertToLRCWithMetadata(lyrics, trackName, artistName)
 				fmt.Printf("[Parallel] Lyrics fetched: %d lines\n", len(lyrics.Lines))
 			} else {
@@ -179,11 +159,6 @@ func FetchCoverAndLyricsParallel(
 	return result
 }
 
-// ========================================
-// Pre-warm Cache for Album/Playlist
-// ========================================
-
-// PreWarmCacheRequest represents a track to pre-warm cache for
 type PreWarmCacheRequest struct {
 	ISRC       string
 	TrackName  string
@@ -192,8 +167,6 @@ type PreWarmCacheRequest struct {
 	Service    string // "tidal", "qobuz", "amazon"
 }
 
-// PreWarmTrackCache pre-fetches track IDs for multiple tracks (for album/playlist)
-// This runs in background while user is viewing the track list
 func PreWarmTrackCache(requests []PreWarmCacheRequest) {
 	if len(requests) == 0 {
 		return
@@ -202,12 +175,10 @@ func PreWarmTrackCache(requests []PreWarmCacheRequest) {
 	fmt.Printf("[Cache] Pre-warming cache for %d tracks...\n", len(requests))
 	cache := GetTrackIDCache()
 
-	// Limit concurrent pre-warm requests
+	semaphore := make(chan struct{}, 3)
-	semaphore := make(chan struct{}, 3) // Max 3 concurrent
 	var wg sync.WaitGroup
 
 	for _, req := range requests {
-		// Skip if already cached
 		if cached := cache.Get(req.ISRC); cached != nil {
 			continue
 		}
@@ -215,8 +186,8 @@ func PreWarmTrackCache(requests []PreWarmCacheRequest) {
 		wg.Add(1)
 		go func(r PreWarmCacheRequest) {
 			defer wg.Done()
-			semaphore <- struct{}{}        // Acquire
+			semaphore <- struct{}{}
-			defer func() { <-semaphore }() // Release
+			defer func() { <-semaphore }()
 
 			switch r.Service {
 			case "tidal":
@@ -233,7 +204,7 @@ func PreWarmTrackCache(requests []PreWarmCacheRequest) {
 	fmt.Printf("[Cache] Pre-warm complete. Cache size: %d\n", cache.Size())
 }
 
-func preWarmTidalCache(isrc, trackName, artistName string) {
+func preWarmTidalCache(isrc, _, _ string) {
 	downloader := NewTidalDownloader()
 	track, err := downloader.SearchTrackByISRC(isrc)
 	if err == nil && track != nil {
@@ -252,38 +223,26 @@ func preWarmQobuzCache(isrc string) {
 }
 
 func preWarmAmazonCache(isrc, spotifyID string) {
-	// Amazon uses SongLink to get URL, so we pre-warm by checking availability
 	client := NewSongLinkClient()
 	availability, err := client.CheckTrackAvailability(spotifyID, isrc)
 	if err == nil && availability != nil && availability.Amazon {
-		// Store Amazon URL in cache (using ISRC as key)
 		GetTrackIDCache().SetAmazon(isrc, availability.AmazonURL)
 		fmt.Printf("[Cache] Cached Amazon URL for ISRC %s\n", isrc)
 	}
 }
 
-// ========================================
-// Exported Functions for Flutter
-// ========================================
-
-// PreWarmCache is called from Flutter to pre-warm cache for album/playlist tracks
-// tracksJSON is a JSON array of {isrc, track_name, artist_name, service}
 func PreWarmCache(tracksJSON string) error {
 	var requests []PreWarmCacheRequest
-	// Parse JSON (simplified - in production use proper JSON parsing)
+
-	// For now, this is called from exports.go with proper parsing
+	go PreWarmTrackCache(requests)
-	
-	go PreWarmTrackCache(requests) // Run in background
 	return nil
 }
 
-// ClearTrackCache clears the track ID cache
 func ClearTrackCache() {
 	GetTrackIDCache().Clear()
 	fmt.Println("[Cache] Track ID cache cleared")
 }
 
-// GetCacheSize returns the current cache size
 func GetCacheSize() int {
 	return GetTrackIDCache().Size()
 }

go_backend/progress.go

@@ -6,8 +6,6 @@ import (
 	"time"
 )
 
-// DownloadProgress represents current download progress
-// Now unified - returns data from multi-progress system
 type DownloadProgress struct {
 	CurrentFile   string  `json:"current_file"`
 	Progress      float64 `json:"progress"`
@@ -15,21 +13,19 @@ type DownloadProgress struct {
 	BytesTotal    int64   `json:"bytes_total"`
 	BytesReceived int64   `json:"bytes_received"`
 	IsDownloading bool    `json:"is_downloading"`
-	Status        string  `json:"status"` // "downloading", "finalizing", "completed"
+	Status        string  `json:"status"`
 }
 
-// ItemProgress represents progress for a single download item
 type ItemProgress struct {
 	ItemID        string  `json:"item_id"`
 	BytesTotal    int64   `json:"bytes_total"`
 	BytesReceived int64   `json:"bytes_received"`
-	Progress      float64 `json:"progress"` // 0.0 to 1.0
+	Progress      float64 `json:"progress"`
-	SpeedMBps     float64 `json:"speed_mbps"` // Download speed in MB/s
+	SpeedMBps     float64 `json:"speed_mbps"`
 	IsDownloading bool    `json:"is_downloading"`
-	Status        string  `json:"status"` // "downloading", "finalizing", "completed"
+	Status        string  `json:"status"`
 }
 
-// MultiProgress holds progress for multiple concurrent downloads
 type MultiProgress struct {
 	Items map[string]*ItemProgress `json:"items"`
 }
@@ -38,22 +34,18 @@ var (
 	downloadDir   string
 	downloadDirMu sync.RWMutex
 
-	// Multi-download progress tracking (unified system)
 	multiProgress = MultiProgress{Items: make(map[string]*ItemProgress)}
 	multiMu       sync.RWMutex
 )
 
-// getProgress returns current download progress from multi-progress system
-// Returns first active item's progress for backward compatibility
 func getProgress() DownloadProgress {
 	multiMu.RLock()
 	defer multiMu.RUnlock()
 
-	// Find first active item
 	for _, item := range multiProgress.Items {
 		return DownloadProgress{
 			CurrentFile:   item.ItemID,
-			Progress:      item.Progress * 100, // Convert to percentage
+			Progress:      item.Progress * 100,
 			BytesTotal:    item.BytesTotal,
 			BytesReceived: item.BytesReceived,
 			IsDownloading: item.IsDownloading,
@@ -64,7 +56,6 @@ func getProgress() DownloadProgress {
 	return DownloadProgress{}
 }
 
-// GetMultiProgress returns progress for all active downloads as JSON
 func GetMultiProgress() string {
 	multiMu.RLock()
 	defer multiMu.RUnlock()
@@ -76,7 +67,6 @@ func GetMultiProgress() string {
 	return string(jsonBytes)
 }
 
-// GetItemProgress returns progress for a specific item as JSON
 func GetItemProgress(itemID string) string {
 	multiMu.RLock()
 	defer multiMu.RUnlock()
@@ -203,13 +193,6 @@ func setDownloadDir(path string) error {
 	return nil
 }
 
-// getDownloadDir returns the default download directory
-func getDownloadDir() string {
-	downloadDirMu.RLock()
-	defer downloadDirMu.RUnlock()
-	return downloadDir
-}
-
 // ItemProgressWriter wraps io.Writer to track download progress for a specific item
 type ItemProgressWriter struct {
 	writer       interface{ Write([]byte) (int, error) }
@@ -239,16 +222,16 @@ func NewItemProgressWriter(w interface{ Write([]byte) (int, error) }, itemID str
 
 // Write implements io.Writer with threshold-based progress updates and speed tracking
 func (pw *ItemProgressWriter) Write(p []byte) (int, error) {
+	if pw.itemID != "" && isDownloadCancelled(pw.itemID) {
+		return 0, ErrDownloadCancelled
+	}
 	n, err := pw.writer.Write(p)
 	if err != nil {
 		return n, err
 	}
 	pw.current += int64(n)
 
-	// Update progress when we've received at least 64KB since last update
-	// Also update on first write to show download has started
 	if pw.lastReported == 0 || pw.current-pw.lastReported >= progressUpdateThreshold {
-		// Calculate speed (MB/s) based on bytes received since last update
 		now := time.Now()
 		elapsed := now.Sub(pw.lastTime).Seconds()
 		var speedMBps float64
@@ -256,7 +239,7 @@ func (pw *ItemProgressWriter) Write(p []byte) (int, error) {
 			bytesInInterval := pw.current - pw.lastBytes
 			speedMBps = float64(bytesInInterval) / (1024 * 1024) / elapsed
 		}
-		
+
 		SetItemBytesReceivedWithSpeed(pw.itemID, pw.current, speedMBps)
 		pw.lastReported = pw.current
 		pw.lastTime = now

go_backend/ratelimit.go

@@ -5,7 +5,6 @@ import (
 	"time"
 )
 
-// RateLimiter implements a sliding window rate limiter
 type RateLimiter struct {
 	mu          sync.Mutex
 	maxRequests int
@@ -13,7 +12,6 @@ type RateLimiter struct {
 	timestamps  []time.Time
 }
 
-// NewRateLimiter creates a new rate limiter with specified max requests per window
 func NewRateLimiter(maxRequests int, window time.Duration) *RateLimiter {
 	return &RateLimiter{
 		maxRequests: maxRequests,
@@ -22,39 +20,31 @@ func NewRateLimiter(maxRequests int, window time.Duration) *RateLimiter {
 	}
 }
 
-// WaitForSlot blocks until a request is allowed under the rate limit
-// Returns immediately if under the limit, otherwise waits until a slot is available
 func (r *RateLimiter) WaitForSlot() {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 
 	now := time.Now()
 
-	// Remove timestamps outside the window
 	r.cleanOldTimestamps(now)
 
-	// If under limit, record and return immediately
 	if len(r.timestamps) < r.maxRequests {
 		r.timestamps = append(r.timestamps, now)
 		return
 	}
 
-	// Calculate wait time until oldest timestamp expires
 	oldestTimestamp := r.timestamps[0]
 	waitUntil := oldestTimestamp.Add(r.window)
 	waitDuration := waitUntil.Sub(now)
 
 	if waitDuration > 0 {
-		// Release lock while waiting
 		r.mu.Unlock()
 		time.Sleep(waitDuration)
 		r.mu.Lock()
 
-		// Clean again after waiting
 		r.cleanOldTimestamps(time.Now())
 	}
 
-	// Record this request
 	r.timestamps = append(r.timestamps, time.Now())
 }
 
@@ -76,8 +66,6 @@ func (r *RateLimiter) cleanOldTimestamps(now time.Time) {
 	}
 }
 
-// TryAcquire attempts to acquire a slot without blocking
-// Returns true if successful, false if rate limit would be exceeded
 func (r *RateLimiter) TryAcquire() bool {
 	r.mu.Lock()
 	defer r.mu.Unlock()
@@ -93,7 +81,6 @@ func (r *RateLimiter) TryAcquire() bool {
 	return false
 }
 
-// Available returns the number of requests available in the current window
 func (r *RateLimiter) Available() int {
 	r.mu.Lock()
 	defer r.mu.Unlock()
@@ -105,7 +92,6 @@ func (r *RateLimiter) Available() int {
 // Global SongLink rate limiter - 9 requests per minute (to be safe, limit is 10)
 var songLinkRateLimiter = NewRateLimiter(9, time.Minute)
 
-// GetSongLinkRateLimiter returns the global SongLink rate limiter
 func GetSongLinkRateLimiter() *RateLimiter {
 	return songLinkRateLimiter
 }

go_backend/romaji.go

@@ -5,7 +5,6 @@ import (
 	"unicode"
 )
 
-// Hiragana to Romaji mapping
 var hiraganaToRomaji = map[rune]string{
 	'あ': "a", 'い': "i", 'う': "u", 'え': "e", 'お': "o",
 	'か': "ka", 'き': "ki", 'く': "ku", 'け': "ke", 'こ': "ko",
@@ -30,7 +29,6 @@ var hiraganaToRomaji = map[rune]string{
 	'ぁ': "a", 'ぃ': "i", 'ぅ': "u", 'ぇ': "e", 'ぉ': "o",
 }
 
-// Katakana to Romaji mapping
 var katakanaToRomaji = map[rune]string{
 	'ア': "a", 'イ': "i", 'ウ': "u", 'エ': "e", 'オ': "o",
 	'カ': "ka", 'キ': "ki", 'ク': "ku", 'ケ': "ke", 'コ': "ko",
@@ -58,7 +56,6 @@ var katakanaToRomaji = map[rune]string{
 	'ヴ': "vu",
 }
 
-// Combination mappings for きゃ, しゃ, etc.
 var combinationHiragana = map[string]string{
 	"きゃ": "kya", "きゅ": "kyu", "きょ": "kyo",
 	"しゃ": "sha", "しゅ": "shu", "しょ": "sho",
@@ -91,7 +88,6 @@ var combinationKatakana = map[string]string{
 	"ウィ": "wi", "ウェ": "we", "ウォ": "wo",
 }
 
-// ContainsJapanese checks if a string contains Japanese characters
 func ContainsJapanese(s string) bool {
 	for _, r := range s {
 		if isHiragana(r) || isKatakana(r) || isKanji(r) {
@@ -114,8 +110,6 @@ func isKanji(r rune) bool {
 		(r >= 0x3400 && r <= 0x4DBF) // CJK Unified Ideographs Extension A
 }
 
-// JapaneseToRomaji converts Japanese text (hiragana/katakana) to romaji
-// Note: Kanji cannot be converted without a dictionary, so they are kept as-is
 func JapaneseToRomaji(text string) string {
 	if !ContainsJapanese(text) {
 		return text
@@ -175,8 +169,6 @@ func JapaneseToRomaji(text string) string {
 	return result.String()
 }
 
-// BuildSearchQuery creates a search query from track name and artist
-// Converts Japanese to romaji if present
 func BuildSearchQuery(trackName, artistName string) string {
 	// Convert Japanese to romaji
 	trackRomaji := JapaneseToRomaji(trackName)
@@ -189,7 +181,6 @@ func BuildSearchQuery(trackName, artistName string) string {
 	return strings.TrimSpace(artistClean + " " + trackClean)
 }
 
-// cleanSearchQuery removes special characters that might interfere with search
 func cleanSearchQuery(s string) string {
 	var result strings.Builder
 	for _, r := range s {
@@ -202,8 +193,6 @@ func cleanSearchQuery(s string) string {
 	return strings.TrimSpace(result.String())
 }
 
-// CleanToASCII removes all non-ASCII characters and keeps only letters, numbers, spaces
-// This is useful for creating search queries that work better with Tidal's search
 func CleanToASCII(s string) string {
 	var result strings.Builder
 	for _, r := range s {

go_backend/songlink.go

@@ -11,12 +11,10 @@ import (
 	"time"
 )
 
-// SongLinkClient handles song.link API interactions
 type SongLinkClient struct {
 	client *http.Client
 }
 
-// TrackAvailability represents track availability on different platforms
 type TrackAvailability struct {
 	SpotifyID string `json:"spotify_id"`
 	Tidal     bool   `json:"tidal"`
@@ -31,32 +29,26 @@ type TrackAvailability struct {
 }
 
 var (
-	// Global SongLink client instance for connection reuse
 	globalSongLinkClient *SongLinkClient
 	songLinkClientOnce   sync.Once
 )
 
-// NewSongLinkClient creates a new SongLink client (returns singleton for connection reuse)
 func NewSongLinkClient() *SongLinkClient {
 	songLinkClientOnce.Do(func() {
 		globalSongLinkClient = &SongLinkClient{
-			client: NewHTTPClientWithTimeout(SongLinkTimeout), // 30s timeout
+			client: NewHTTPClientWithTimeout(SongLinkTimeout),
 		}
 	})
 	return globalSongLinkClient
 }
 
-// CheckTrackAvailability checks track availability on streaming platforms
 func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc string) (*TrackAvailability, error) {
-	// Validate Spotify ID format (should be 22 characters alphanumeric)
 	if spotifyTrackID == "" {
 		return nil, fmt.Errorf("spotify track ID is empty")
 	}
 	
-	// Use global rate limiter - blocks until request is allowed
 	songLinkRateLimiter.WaitForSlot()
 
-	// Build API URL
 	spotifyBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9vcGVuLnNwb3RpZnkuY29tL3RyYWNrLw==")
 	spotifyURL := fmt.Sprintf("%s%s", string(spotifyBase), spotifyTrackID)
 
@@ -68,7 +60,6 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 		return nil, fmt.Errorf("failed to create request: %w", err)
 	}
 
-	// Use retry logic with User-Agent
 	retryConfig := DefaultRetryConfig()
 	resp, err := DoRequestWithRetry(s.client, req, retryConfig)
 	if err != nil {
@@ -76,7 +67,6 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 	}
 	defer resp.Body.Close()
 
-	// Handle specific error codes
 	if resp.StatusCode == 400 {
 		return nil, fmt.Errorf("track not found on SongLink (invalid Spotify ID or track unavailable)")
 	}
@@ -109,27 +99,22 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 		SpotifyID: spotifyTrackID,
 	}
 
-	// Check Tidal
 	if tidalLink, ok := songLinkResp.LinksByPlatform["tidal"]; ok && tidalLink.URL != "" {
 		availability.Tidal = true
 		availability.TidalURL = tidalLink.URL
 	}
 
-	// Check Amazon
 	if amazonLink, ok := songLinkResp.LinksByPlatform["amazonMusic"]; ok && amazonLink.URL != "" {
 		availability.Amazon = true
 		availability.AmazonURL = amazonLink.URL
 	}
 
-	// Check Deezer
 	if deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]; ok && deezerLink.URL != "" {
 		availability.Deezer = true
 		availability.DeezerURL = deezerLink.URL
-		// Extract Deezer ID from URL (e.g., https://www.deezer.com/track/123456)
 		availability.DeezerID = extractDeezerIDFromURL(deezerLink.URL)
 	}
 
-	// Check Qobuz using ISRC (SongLink doesn't support Qobuz directly)
 	if isrc != "" {
 		availability.Qobuz = checkQobuzAvailability(isrc)
 	}
@@ -137,7 +122,6 @@ func (s *SongLinkClient) CheckTrackAvailability(spotifyTrackID string, isrc stri
 	return availability, nil
 }
 
-// GetStreamingURLs gets streaming URLs for a Spotify track
 func (s *SongLinkClient) GetStreamingURLs(spotifyTrackID string) (map[string]string, error) {
 	availability, err := s.CheckTrackAvailability(spotifyTrackID, "")
 	if err != nil {
@@ -191,12 +175,9 @@ func checkQobuzAvailability(isrc string) bool {
 
 // extractDeezerIDFromURL extracts Deezer track/album/artist ID from URL
 func extractDeezerIDFromURL(deezerURL string) string {
-	// URL format: https://www.deezer.com/track/123456 or https://www.deezer.com/en/track/123456
 	parts := strings.Split(deezerURL, "/")
 	if len(parts) > 0 {
-		// Get the last part which should be the ID
 		lastPart := parts[len(parts)-1]
-		// Remove any query parameters
 		if idx := strings.Index(lastPart, "?"); idx > 0 {
 			lastPart = lastPart[:idx]
 		}
@@ -205,7 +186,6 @@ func extractDeezerIDFromURL(deezerURL string) string {
 	return ""
 }
 
-// GetDeezerIDFromSpotify converts a Spotify track ID to Deezer track ID using SongLink
 func (s *SongLinkClient) GetDeezerIDFromSpotify(spotifyTrackID string) (string, error) {
 	availability, err := s.CheckTrackAvailability(spotifyTrackID, "")
 	if err != nil {
@@ -227,7 +207,6 @@ type AlbumAvailability struct {
 	DeezerID  string `json:"deezer_id,omitempty"`
 }
 
-// CheckAlbumAvailability checks album availability on streaming platforms using SongLink
 func (s *SongLinkClient) CheckAlbumAvailability(spotifyAlbumID string) (*AlbumAvailability, error) {
 	// Use global rate limiter
 	songLinkRateLimiter.WaitForSlot()
@@ -274,7 +253,6 @@ func (s *SongLinkClient) CheckAlbumAvailability(spotifyAlbumID string) (*AlbumAv
 		SpotifyID: spotifyAlbumID,
 	}
 
-	// Check Deezer
 	if deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]; ok && deezerLink.URL != "" {
 		availability.Deezer = true
 		availability.DeezerURL = deezerLink.URL
@@ -298,24 +276,16 @@ func (s *SongLinkClient) GetDeezerAlbumIDFromSpotify(spotifyAlbumID string) (str
 	return availability.DeezerID, nil
 }
 
-// ========================================
-// Deezer ID Support - Query SongLink using Deezer as source
-// ========================================
-
-// CheckAvailabilityFromDeezer checks track availability using Deezer track ID as source
 // This is useful when we have Deezer metadata and want to find the track on other platforms
 func (s *SongLinkClient) CheckAvailabilityFromDeezer(deezerTrackID string) (*TrackAvailability, error) {
 	if deezerTrackID == "" {
 		return nil, fmt.Errorf("deezer track ID is empty")
 	}
 	
-	// Use global rate limiter
 	songLinkRateLimiter.WaitForSlot()
 
-	// Build Deezer URL
 	deezerURL := fmt.Sprintf("https://www.deezer.com/track/%s", deezerTrackID)
 
-	// Build API URL using Deezer URL as source
 	apiBase, _ := base64.StdEncoding.DecodeString("aHR0cHM6Ly9hcGkuc29uZy5saW5rL3YxLWFscGhhLjEvbGlua3M/dXJsPQ==")
 	apiURL := fmt.Sprintf("%s%s&userCountry=US", string(apiBase), url.QueryEscape(deezerURL))
 
@@ -371,25 +341,20 @@ func (s *SongLinkClient) CheckAvailabilityFromDeezer(deezerTrackID string) (*Tra
 		DeezerID: deezerTrackID,
 	}
 
-	// Check Spotify
 	if spotifyLink, ok := songLinkResp.LinksByPlatform["spotify"]; ok && spotifyLink.URL != "" {
-		// Extract Spotify ID from URL
 		availability.SpotifyID = extractSpotifyIDFromURL(spotifyLink.URL)
 	}
 
-	// Check Tidal
 	if tidalLink, ok := songLinkResp.LinksByPlatform["tidal"]; ok && tidalLink.URL != "" {
 		availability.Tidal = true
 		availability.TidalURL = tidalLink.URL
 	}
 
-	// Check Amazon
 	if amazonLink, ok := songLinkResp.LinksByPlatform["amazonMusic"]; ok && amazonLink.URL != "" {
 		availability.Amazon = true
 		availability.AmazonURL = amazonLink.URL
 	}
 
-	// Check Deezer URL
 	if deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]; ok && deezerLink.URL != "" {
 		availability.DeezerURL = deezerLink.URL
 	}
@@ -397,7 +362,6 @@ func (s *SongLinkClient) CheckAvailabilityFromDeezer(deezerTrackID string) (*Tra
 	return availability, nil
 }
 
-// CheckAvailabilityByPlatform checks track availability using any supported platform
 // platform: "spotify", "deezer", "tidal", "amazonMusic", "appleMusic", "youtube", etc.
 // entityType: "song" or "album"
 // entityID: the ID on that platform
@@ -459,24 +423,20 @@ func (s *SongLinkClient) CheckAvailabilityByPlatform(platform, entityType, entit
 
 	availability := &TrackAvailability{}
 
-	// Check Spotify
 	if spotifyLink, ok := songLinkResp.LinksByPlatform["spotify"]; ok && spotifyLink.URL != "" {
 		availability.SpotifyID = extractSpotifyIDFromURL(spotifyLink.URL)
 	}
 
-	// Check Tidal
 	if tidalLink, ok := songLinkResp.LinksByPlatform["tidal"]; ok && tidalLink.URL != "" {
 		availability.Tidal = true
 		availability.TidalURL = tidalLink.URL
 	}
 
-	// Check Amazon
 	if amazonLink, ok := songLinkResp.LinksByPlatform["amazonMusic"]; ok && amazonLink.URL != "" {
 		availability.Amazon = true
 		availability.AmazonURL = amazonLink.URL
 	}
 
-	// Check Deezer
 	if deezerLink, ok := songLinkResp.LinksByPlatform["deezer"]; ok && deezerLink.URL != "" {
 		availability.Deezer = true
 		availability.DeezerURL = deezerLink.URL
@@ -488,10 +448,8 @@ func (s *SongLinkClient) CheckAvailabilityByPlatform(platform, entityType, entit
 
 // extractSpotifyIDFromURL extracts Spotify track ID from URL
 func extractSpotifyIDFromURL(spotifyURL string) string {
-	// URL format: https://open.spotify.com/track/0Jcij1eWd5bDMU5iPbxe2i
 	parts := strings.Split(spotifyURL, "/track/")
 	if len(parts) > 1 {
-		// Get the ID part and remove any query parameters
 		idPart := parts[1]
 		if idx := strings.Index(idPart, "?"); idx > 0 {
 			idPart = idPart[:idx]
@@ -501,7 +459,6 @@ func extractSpotifyIDFromURL(spotifyURL string) string {
 	return ""
 }
 
-// GetSpotifyIDFromDeezer converts a Deezer track ID to Spotify track ID using SongLink
 func (s *SongLinkClient) GetSpotifyIDFromDeezer(deezerTrackID string) (string, error) {
 	availability, err := s.CheckAvailabilityFromDeezer(deezerTrackID)
 	if err != nil {
@@ -529,7 +486,6 @@ func (s *SongLinkClient) GetTidalURLFromDeezer(deezerTrackID string) (string, er
 	return availability.TidalURL, nil
 }
 
-// GetAmazonURLFromDeezer converts a Deezer track ID to Amazon Music URL using SongLink
 func (s *SongLinkClient) GetAmazonURLFromDeezer(deezerTrackID string) (string, error) {
 	availability, err := s.CheckAvailabilityFromDeezer(deezerTrackID)
 	if err != nil {

go_backend/spotify.go

@@ -2,7 +2,6 @@ package gobackend
 
 import (
 	"context"
-	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -17,15 +16,14 @@ import (
 )
 
 const (
-	spotifyTokenURL     = "https://accounts.spotify.com/api/token"
+	spotifyTokenURL = "https://accounts.spotify.com/api/token"
-	playlistBaseURL     = "https://api.spotify.com/v1/playlists/%s"
+	playlistBaseURL = "https://api.spotify.com/v1/playlists/%s"
-	albumBaseURL        = "https://api.spotify.com/v1/albums/%s"
+	albumBaseURL    = "https://api.spotify.com/v1/albums/%s"
-	trackBaseURL        = "https://api.spotify.com/v1/tracks/%s"
+	trackBaseURL    = "https://api.spotify.com/v1/tracks/%s"
-	artistBaseURL       = "https://api.spotify.com/v1/artists/%s"
+	artistBaseURL   = "https://api.spotify.com/v1/artists/%s"
-	artistAlbumsURL     = "https://api.spotify.com/v1/artists/%s/albums"
+	artistAlbumsURL = "https://api.spotify.com/v1/artists/%s/albums"
-	searchBaseURL       = "https://api.spotify.com/v1/search"
+	searchBaseURL   = "https://api.spotify.com/v1/search"
-	
+
-	// Cache TTL settings
 	artistCacheTTL = 10 * time.Minute
 	searchCacheTTL = 5 * time.Minute
 	albumCacheTTL  = 10 * time.Minute
@@ -33,7 +31,6 @@ const (
 
 var errInvalidSpotifyURL = errors.New("invalid or unsupported Spotify URL")
 
-// cacheEntry holds cached data with expiration
 type cacheEntry struct {
 	data      interface{}
 	expiresAt time.Time
@@ -43,34 +40,33 @@ func (e *cacheEntry) isExpired() bool {
 	return time.Now().After(e.expiresAt)
 }
 
-// SpotifyMetadataClient handles Spotify API interactions
 type SpotifyMetadataClient struct {
 	httpClient     *http.Client
 	clientID       string
 	clientSecret   string
 	cachedToken    string
 	tokenExpiresAt time.Time
-	tokenMu        sync.Mutex // Protects token cache for concurrent access
+	tokenMu        sync.Mutex
 	rng            *rand.Rand
 	rngMu          sync.Mutex
 	userAgent      string
-	
+
-	// Caches to reduce API calls
+	artistCache map[string]*cacheEntry
-	artistCache map[string]*cacheEntry // key: artistID
+	searchCache map[string]*cacheEntry
-	searchCache map[string]*cacheEntry // key: query+type
+	albumCache  map[string]*cacheEntry
-	albumCache  map[string]*cacheEntry // key: albumID
 	cacheMu     sync.RWMutex
 }
 
-// Custom credentials storage (set from Flutter)
 var (
 	customClientID     string
 	customClientSecret string
 	credentialsMu      sync.RWMutex
 )
 
+// ErrNoSpotifyCredentials is returned when Spotify credentials are not configured
+var ErrNoSpotifyCredentials = errors.New("Spotify credentials not configured. Please set your own Client ID and Secret in Settings, or use Deezer as metadata source (free, no credentials required)")
+
 // SetSpotifyCredentials sets custom Spotify API credentials
-// Pass empty strings to use default credentials
 func SetSpotifyCredentials(clientID, clientSecret string) {
 	credentialsMu.Lock()
 	defer credentialsMu.Unlock()
@@ -78,42 +74,50 @@ func SetSpotifyCredentials(clientID, clientSecret string) {
 	customClientSecret = clientSecret
 }
 
-// getCredentials returns the current credentials (custom or default)
+func HasSpotifyCredentials() bool {
-func getCredentials() (string, string) {
 	credentialsMu.RLock()
 	defer credentialsMu.RUnlock()
-	
+
 	if customClientID != "" && customClientSecret != "" {
-		return customClientID, customClientSecret
+		return true
-	}
-	
-	// Fall back to default credentials
-	clientID := os.Getenv("SPOTIFY_CLIENT_ID")
-	if clientID == "" {
-		if decoded, err := base64.StdEncoding.DecodeString("NWY1NzNjOTYyMDQ5NGJhZTg3ODkwYzBmMDhhNjAyOTM="); err == nil {
-			clientID = string(decoded)
-		}
 	}
 
-	clientSecret := os.Getenv("SPOTIFY_CLIENT_SECRET")
+	if os.Getenv("SPOTIFY_CLIENT_ID") != "" && os.Getenv("SPOTIFY_CLIENT_SECRET") != "" {
-	if clientSecret == "" {
+		return true
-		if decoded, err := base64.StdEncoding.DecodeString("MjEyNDc2ZDliMGYzNDcyZWFhNzYyZDkwYjE5YjBiYTg="); err == nil {
-			clientSecret = string(decoded)
-		}
 	}
-	
+
-	return clientID, clientSecret
+	return false
 }
 
-// NewSpotifyMetadataClient creates a new Spotify client
+// getCredentials returns the current credentials or error if not configured
-func NewSpotifyMetadataClient() *SpotifyMetadataClient {
+func getCredentials() (string, string, error) {
+	credentialsMu.RLock()
+	defer credentialsMu.RUnlock()
+
+	if customClientID != "" && customClientSecret != "" {
+		return customClientID, customClientSecret, nil
+	}
+
+	clientID := os.Getenv("SPOTIFY_CLIENT_ID")
+	clientSecret := os.Getenv("SPOTIFY_CLIENT_SECRET")
+
+	if clientID != "" && clientSecret != "" {
+		return clientID, clientSecret, nil
+	}
+
+	return "", "", ErrNoSpotifyCredentials
+}
+
+func NewSpotifyMetadataClient() (*SpotifyMetadataClient, error) {
+	clientID, clientSecret, err := getCredentials()
+	if err != nil {
+		return nil, err
+	}
+
 	src := rand.NewSource(time.Now().UnixNano())
 
-	// Get credentials (custom or default)
-	clientID, clientSecret := getCredentials()
-
 	c := &SpotifyMetadataClient{
-		httpClient:   NewHTTPClientWithTimeout(15 * time.Second), // Use shared transport for connection pooling
+		httpClient:   NewHTTPClientWithTimeout(15 * time.Second),
 		clientID:     clientID,
 		clientSecret: clientSecret,
 		rng:          rand.New(src),
@@ -122,10 +126,9 @@ func NewSpotifyMetadataClient() *SpotifyMetadataClient {
 		albumCache:   make(map[string]*cacheEntry),
 	}
 	c.userAgent = c.randomUserAgent()
-	return c
+	return c, nil
 }
 
-// TrackMetadata represents track information
 type TrackMetadata struct {
 	SpotifyID   string `json:"spotify_id,omitempty"`
 	Artists     string `json:"artists"`
@@ -140,9 +143,9 @@ type TrackMetadata struct {
 	DiscNumber  int    `json:"disc_number,omitempty"`
 	ExternalURL string `json:"external_urls"`
 	ISRC        string `json:"isrc"`
+	AlbumType   string `json:"album_type,omitempty"` // album, single, ep, compilation
 }
 
-// AlbumTrackMetadata holds per-track info for album/playlist
 type AlbumTrackMetadata struct {
 	SpotifyID   string `json:"spotify_id,omitempty"`
 	Artists     string `json:"artists"`
@@ -159,24 +162,25 @@ type AlbumTrackMetadata struct {
 	ISRC        string `json:"isrc"`
 	AlbumID     string `json:"album_id,omitempty"`
 	AlbumURL    string `json:"album_url,omitempty"`
+	AlbumType   string `json:"album_type,omitempty"`
 }
 
-// AlbumInfoMetadata holds album information
 type AlbumInfoMetadata struct {
 	TotalTracks int    `json:"total_tracks"`
 	Name        string `json:"name"`
 	ReleaseDate string `json:"release_date"`
 	Artists     string `json:"artists"`
 	Images      string `json:"images"`
+	Genre       string `json:"genre,omitempty"`
+	Label       string `json:"label,omitempty"`
+	Copyright   string `json:"copyright,omitempty"`
 }
 
-// AlbumResponsePayload is the response for album requests
 type AlbumResponsePayload struct {
 	AlbumInfo AlbumInfoMetadata    `json:"album_info"`
 	TrackList []AlbumTrackMetadata `json:"track_list"`
 }
 
-// PlaylistInfoMetadata holds playlist information
 type PlaylistInfoMetadata struct {
 	Tracks struct {
 		Total int `json:"total"`
@@ -188,13 +192,11 @@ type PlaylistInfoMetadata struct {
 	} `json:"owner"`
 }
 
-// PlaylistResponsePayload is the response for playlist requests
 type PlaylistResponsePayload struct {
 	PlaylistInfo PlaylistInfoMetadata `json:"playlist_info"`
 	TrackList    []AlbumTrackMetadata `json:"track_list"`
 }
 
-// ArtistInfoMetadata holds artist information
 type ArtistInfoMetadata struct {
 	ID         string `json:"id"`
 	Name       string `json:"name"`
@@ -203,7 +205,6 @@ type ArtistInfoMetadata struct {
 	Popularity int    `json:"popularity"`
 }
 
-// ArtistAlbumMetadata holds album info for artist discography
 type ArtistAlbumMetadata struct {
 	ID          string `json:"id"`
 	Name        string `json:"name"`
@@ -214,24 +215,20 @@ type ArtistAlbumMetadata struct {
 	Artists     string `json:"artists"`
 }
 
-// ArtistResponsePayload is the response for artist requests
 type ArtistResponsePayload struct {
 	ArtistInfo ArtistInfoMetadata    `json:"artist_info"`
 	Albums     []ArtistAlbumMetadata `json:"albums"`
 }
 
-// TrackResponse is the response for single track requests
 type TrackResponse struct {
 	Track TrackMetadata `json:"track"`
 }
 
-// SearchResult represents search results
 type SearchResult struct {
 	Tracks []TrackMetadata `json:"tracks"`
 	Total  int             `json:"total"`
 }
 
-// SearchArtistResult represents an artist in search results
 type SearchArtistResult struct {
 	ID         string `json:"id"`
 	Name       string `json:"name"`
@@ -240,7 +237,6 @@ type SearchArtistResult struct {
 	Popularity int    `json:"popularity"`
 }
 
-// SearchAllResult represents combined search results for tracks and artists
 type SearchAllResult struct {
 	Tracks  []TrackMetadata      `json:"tracks"`
 	Artists []SearchArtistResult `json:"artists"`
@@ -257,7 +253,6 @@ type accessTokenResponse struct {
 	TokenType   string      `json:"token_type"`
 }
 
-// Internal API response types
 type image struct {
 	URL string `json:"url"`
 }
@@ -283,6 +278,7 @@ type albumSimplified struct {
 	Images      []image     `json:"images"`
 	ExternalURL externalURL `json:"external_urls"`
 	Artists     []artist    `json:"artists"`
+	AlbumType   string      `json:"album_type"`
 }
 
 type trackFull struct {
@@ -297,7 +293,6 @@ type trackFull struct {
 	Artists     []artist        `json:"artists"`
 }
 
-// GetFilteredData fetches and formats Spotify data
 func (c *SpotifyMetadataClient) GetFilteredData(ctx context.Context, spotifyURL string, batch bool, delay time.Duration) (interface{}, error) {
 	parsed, err := parseSpotifyURI(spotifyURL)
 	if err != nil {
@@ -323,7 +318,6 @@ func (c *SpotifyMetadataClient) GetFilteredData(ctx context.Context, spotifyURL
 	}
 }
 
-// SearchTracks searches for tracks on Spotify
 func (c *SpotifyMetadataClient) SearchTracks(ctx context.Context, query string, limit int) (*SearchResult, error) {
 	token, err := c.getAccessToken(ctx)
 	if err != nil {
@@ -331,14 +325,14 @@ func (c *SpotifyMetadataClient) SearchTracks(ctx context.Context, query string,
 	}
 
 	searchURL := fmt.Sprintf("%s?q=%s&type=track&limit=%d", searchBaseURL, url.QueryEscape(query), limit)
-	
+
 	var response struct {
 		Tracks struct {
 			Items []trackFull `json:"items"`
 			Total int         `json:"total"`
 		} `json:"tracks"`
 	}
-	
+
 	if err := c.getJSON(ctx, searchURL, token, &response); err != nil {
 		return nil, err
 	}
@@ -363,18 +357,16 @@ func (c *SpotifyMetadataClient) SearchTracks(ctx context.Context, query string,
 			DiscNumber:  track.DiscNumber,
 			ExternalURL: track.ExternalURL.Spotify,
 			ISRC:        track.ExternalID.ISRC,
+			AlbumType:   track.Album.AlbumType,
 		})
 	}
 
 	return result, nil
 }
 
-// SearchAll searches for tracks and artists on Spotify
 func (c *SpotifyMetadataClient) SearchAll(ctx context.Context, query string, trackLimit, artistLimit int) (*SearchAllResult, error) {
-	// Create cache key
 	cacheKey := fmt.Sprintf("all:%s:%d:%d", query, trackLimit, artistLimit)
-	
+
-	// Check cache first
 	c.cacheMu.RLock()
 	if entry, ok := c.searchCache[cacheKey]; ok && !entry.isExpired() {
 		c.cacheMu.RUnlock()
@@ -388,24 +380,24 @@ func (c *SpotifyMetadataClient) SearchAll(ctx context.Context, query string, tra
 	}
 
 	searchURL := fmt.Sprintf("%s?q=%s&type=track,artist&limit=%d", searchBaseURL, url.QueryEscape(query), trackLimit)
-	
+
 	var response struct {
 		Tracks struct {
 			Items []trackFull `json:"items"`
 		} `json:"tracks"`
 		Artists struct {
 			Items []struct {
-				ID         string  `json:"id"`
+				ID        string  `json:"id"`
-				Name       string  `json:"name"`
+				Name      string  `json:"name"`
-				Images     []image `json:"images"`
+				Images    []image `json:"images"`
-				Followers  struct {
+				Followers struct {
 					Total int `json:"total"`
 				} `json:"followers"`
 				Popularity int `json:"popularity"`
 			} `json:"items"`
 		} `json:"artists"`
 	}
-	
+
 	if err := c.getJSON(ctx, searchURL, token, &response); err != nil {
 		return nil, err
 	}
@@ -430,15 +422,15 @@ func (c *SpotifyMetadataClient) SearchAll(ctx context.Context, query string, tra
 			DiscNumber:  track.DiscNumber,
 			ExternalURL: track.ExternalURL.Spotify,
 			ISRC:        track.ExternalID.ISRC,
+			AlbumType:   track.Album.AlbumType,
 		})
 	}
 
-	// Limit artists to artistLimit
 	artistCount := len(response.Artists.Items)
 	if artistCount > artistLimit {
 		artistCount = artistLimit
 	}
-	
+
 	for i := 0; i < artistCount; i++ {
 		artist := response.Artists.Items[i]
 		result.Artists = append(result.Artists, SearchArtistResult{
@@ -450,7 +442,6 @@ func (c *SpotifyMetadataClient) SearchAll(ctx context.Context, query string, tra
 		})
 	}
 
-	// Store in cache
 	c.cacheMu.Lock()
 	c.searchCache[cacheKey] = &cacheEntry{
 		data:      result,
@@ -487,7 +478,6 @@ func (c *SpotifyMetadataClient) fetchTrack(ctx context.Context, trackID, token s
 }
 
 func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token string) (*AlbumResponsePayload, error) {
-	// Check cache first
 	c.cacheMu.RLock()
 	if entry, ok := c.albumCache[albumID]; ok && !entry.isExpired() {
 		c.cacheMu.RUnlock()
@@ -495,7 +485,6 @@ func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token s
 	}
 	c.cacheMu.RUnlock()
 
-	// Track item structure for pagination
 	type trackItem struct {
 		ID          string      `json:"id"`
 		Name        string      `json:"name"`
@@ -531,11 +520,9 @@ func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token s
 		Images:      albumImage,
 	}
 
-	// Collect all tracks (including paginated)
 	allTrackItems := data.Tracks.Items
 	nextURL := data.Tracks.Next
-	
+
-	// Fetch remaining tracks using pagination (no limit)
 	for nextURL != "" {
 		var pageData struct {
 			Items []trackItem `json:"items"`
@@ -557,13 +544,12 @@ func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token s
 		trackIDs[i] = item.ID
 	}
 
-	// Fetch ISRCs in parallel for ALL tracks (like Deezer implementation)
 	isrcMap := c.fetchISRCsParallel(ctx, trackIDs, token)
 
 	tracks := make([]AlbumTrackMetadata, 0, len(allTrackItems))
 	for _, item := range allTrackItems {
 		isrc := isrcMap[item.ID]
-		
+
 		tracks = append(tracks, AlbumTrackMetadata{
 			SpotifyID:   item.ID,
 			Artists:     joinArtists(item.Artists),
@@ -587,7 +573,6 @@ func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token s
 		TrackList: tracks,
 	}
 
-	// Store in cache
 	c.cacheMu.Lock()
 	c.albumCache[albumID] = &cacheEntry{
 		data:      result,
@@ -598,49 +583,44 @@ func (c *SpotifyMetadataClient) fetchAlbum(ctx context.Context, albumID, token s
 	return result, nil
 }
 
-// fetchISRCsParallel fetches ISRCs for multiple tracks in parallel
-// Similar to Deezer implementation for consistency
 func (c *SpotifyMetadataClient) fetchISRCsParallel(ctx context.Context, trackIDs []string, token string) map[string]string {
-	const maxParallelISRC = 10 // Max concurrent ISRC fetches
+	const maxParallelISRC = 10
-	
+
 	result := make(map[string]string)
 	var resultMu sync.Mutex
-	
+
 	if len(trackIDs) == 0 {
 		return result
 	}
-	
+
-	// Use semaphore to limit concurrent requests
 	sem := make(chan struct{}, maxParallelISRC)
 	var wg sync.WaitGroup
-	
+
 	for _, trackID := range trackIDs {
 		wg.Add(1)
 		go func(id string) {
 			defer wg.Done()
-			
+
-			// Acquire semaphore
 			select {
 			case sem <- struct{}{}:
 				defer func() { <-sem }()
 			case <-ctx.Done():
 				return
 			}
-			
+
 			isrc := c.fetchTrackISRC(ctx, id, token)
-			
+
 			resultMu.Lock()
 			result[id] = isrc
 			resultMu.Unlock()
 		}(trackID)
 	}
-	
+
 	wg.Wait()
 	return result
 }
 
 func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, token string) (*PlaylistResponsePayload, error) {
-	// First request to get playlist info and first batch of tracks
 	var data struct {
 		Name   string  `json:"name"`
 		Images []image `json:"images"`
@@ -666,10 +646,8 @@ func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, t
 	info.Owner.Name = data.Name
 	info.Owner.Images = firstImageURL(data.Images)
 
-	// Pre-allocate with expected capacity
 	tracks := make([]AlbumTrackMetadata, 0, data.Tracks.Total)
-	
+
-	// Add first batch of tracks
 	for _, item := range data.Tracks.Items {
 		if item.Track == nil {
 			continue
@@ -693,9 +671,8 @@ func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, t
 		})
 	}
 
-	// Fetch remaining tracks using pagination (NO LIMIT - fetch all tracks)
 	nextURL := data.Tracks.Next
-	
+
 	for nextURL != "" {
 		var pageData struct {
 			Items []struct {
@@ -705,7 +682,6 @@ func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, t
 		}
 
 		if err := c.getJSON(ctx, nextURL, token, &pageData); err != nil {
-			// Log error but return what we have so far
 			fmt.Printf("[Spotify] Warning: failed to fetch page, returning %d tracks: %v\n", len(tracks), err)
 			break
 		}
@@ -745,7 +721,6 @@ func (c *SpotifyMetadataClient) fetchPlaylist(ctx context.Context, playlistID, t
 }
 
 func (c *SpotifyMetadataClient) fetchArtist(ctx context.Context, artistID, token string) (*ArtistResponsePayload, error) {
-	// Check cache first
 	c.cacheMu.RLock()
 	if entry, ok := c.artistCache[artistID]; ok && !entry.isExpired() {
 		c.cacheMu.RUnlock()
@@ -753,12 +728,11 @@ func (c *SpotifyMetadataClient) fetchArtist(ctx context.Context, artistID, token
 	}
 	c.cacheMu.RUnlock()
 
-	// Fetch artist info
 	var artistData struct {
-		ID         string  `json:"id"`
+		ID        string  `json:"id"`
-		Name       string  `json:"name"`
+		Name      string  `json:"name"`
-		Images     []image `json:"images"`
+		Images    []image `json:"images"`
-		Followers  struct {
+		Followers struct {
 			Total int `json:"total"`
 		} `json:"followers"`
 		Popularity int `json:"popularity"`
@@ -776,7 +750,6 @@ func (c *SpotifyMetadataClient) fetchArtist(ctx context.Context, artistID, token
 		Popularity: artistData.Popularity,
 	}
 
-	// Fetch artist albums (all types: album, single, compilation)
 	albums := make([]ArtistAlbumMetadata, 0)
 	offset := 0
 	limit := 50
@@ -816,13 +789,11 @@ func (c *SpotifyMetadataClient) fetchArtist(ctx context.Context, artistID, token
 			})
 		}
 
-		// Check if there are more albums
 		if albumsData.Next == "" || len(albumsData.Items) < limit {
 			break
 		}
 		offset += limit
 
-		// Safety limit to prevent infinite loops
 		if offset > 500 {
 			break
 		}
@@ -833,7 +804,6 @@ func (c *SpotifyMetadataClient) fetchArtist(ctx context.Context, artistID, token
 		Albums:     albums,
 	}
 
-	// Store in cache
 	c.cacheMu.Lock()
 	c.artistCache[artistID] = &cacheEntry{
 		data:      result,
@@ -904,7 +874,6 @@ func (c *SpotifyMetadataClient) getJSON(ctx context.Context, endpoint, token str
 		return err
 	}
 
-	// Set headers (same as PC version baseHeaders)
 	req.Header.Set("User-Agent", c.userAgent)
 	req.Header.Set("Accept", "application/json")
 	req.Header.Set("Accept-Language", "en-US,en;q=0.9")
@@ -940,16 +909,15 @@ func (c *SpotifyMetadataClient) randomUserAgent() string {
 	c.rngMu.Lock()
 	defer c.rngMu.Unlock()
 
-	// Use Mac User-Agent format (same as PC version)
+	macMajor := c.rng.Intn(4) + 11
-	macMajor := c.rng.Intn(4) + 11    // 11-14
+	macMinor := c.rng.Intn(5) + 4          // 4-8
-	macMinor := c.rng.Intn(5) + 4     // 4-8
+	webkitMajor := c.rng.Intn(7) + 530     // 530-536
-	webkitMajor := c.rng.Intn(7) + 530 // 530-536
+	webkitMinor := c.rng.Intn(7) + 30      // 30-36
-	webkitMinor := c.rng.Intn(7) + 30  // 30-36
+	chromeMajor := c.rng.Intn(25) + 80     // 80-104
-	chromeMajor := c.rng.Intn(25) + 80 // 80-104
 	chromeBuild := c.rng.Intn(1500) + 3000 // 3000-4499
-	chromePatch := c.rng.Intn(65) + 60 // 60-124
+	chromePatch := c.rng.Intn(65) + 60     // 60-124
-	safariMajor := c.rng.Intn(7) + 530 // 530-536
+	safariMajor := c.rng.Intn(7) + 530     // 530-536
-	safariMinor := c.rng.Intn(6) + 30  // 30-35
+	safariMinor := c.rng.Intn(6) + 30      // 30-35
 
 	return fmt.Sprintf(
 		"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_%d_%d) AppleWebKit/%d.%d (KHTML, like Gecko) Chrome/%d.0.%d.%d Safari/%d.%d",
@@ -966,7 +934,6 @@ func parseSpotifyURI(input string) (spotifyURI, error) {
 		return spotifyURI{}, errInvalidSpotifyURL
 	}
 
-	// Handle spotify: URI format
 	if strings.HasPrefix(trimmed, "spotify:") {
 		parts := strings.Split(trimmed, ":")
 		if len(parts) == 3 {
@@ -977,13 +944,11 @@ func parseSpotifyURI(input string) (spotifyURI, error) {
 		}
 	}
 
-	// Handle URL format
 	parsed, err := url.Parse(trimmed)
 	if err != nil {
 		return spotifyURI{}, err
 	}
 
-	// Handle embed.spotify.com URLs
 	if parsed.Host == "embed.spotify.com" {
 		if parsed.RawQuery == "" {
 			return spotifyURI{}, errInvalidSpotifyURL
@@ -996,7 +961,6 @@ func parseSpotifyURI(input string) (spotifyURI, error) {
 		return parseSpotifyURI(embedded)
 	}
 
-	// Handle plain ID (no scheme/host) - defaults to playlist
 	if parsed.Scheme == "" && parsed.Host == "" {
 		id := strings.Trim(strings.TrimSpace(parsed.Path), "/")
 		if id == "" {
@@ -1022,7 +986,6 @@ func parseSpotifyURI(input string) (spotifyURI, error) {
 		return spotifyURI{}, errInvalidSpotifyURL
 	}
 
-	// Skip intl- prefix if present
 	if strings.HasPrefix(parts[0], "intl-") {
 		parts = parts[1:]
 	}
@@ -1030,7 +993,6 @@ func parseSpotifyURI(input string) (spotifyURI, error) {
 		return spotifyURI{}, errInvalidSpotifyURL
 	}
 
-	// Handle standard URLs: /album/{id}, /track/{id}, /playlist/{id}, /artist/{id}
 	if len(parts) == 2 {
 		switch parts[0] {
 		case "album", "track", "playlist", "artist":
@@ -1038,7 +1000,6 @@ func parseSpotifyURI(input string) (spotifyURI, error) {
 		}
 	}
 
-	// Handle nested playlist URLs: /user/{user}/playlist/{id}
 	if len(parts) == 4 && parts[2] == "playlist" {
 		return spotifyURI{Type: "playlist", ID: parts[3]}, nil
 	}

ios/Runner/AppDelegate.swift

@@ -120,6 +120,12 @@ import Gobackend  // Import Go framework
             let itemId = args["item_id"] as! String
             GobackendClearItemProgress(itemId)
             return nil
+
+        case "cancelDownload":
+            let args = call.arguments as! [String: Any]
+            let itemId = args["item_id"] as! String
+            GobackendCancelDownload(itemId)
+            return nil
             
         case "setDownloadDirectory":
             let args = call.arguments as! [String: Any]
@@ -155,7 +161,8 @@ import Gobackend  // Import Go framework
             let spotifyId = args["spotify_id"] as! String
             let trackName = args["track_name"] as! String
             let artistName = args["artist_name"] as! String
-            let response = GobackendFetchLyrics(spotifyId, trackName, artistName, &error)
+            let durationMs = args["duration_ms"] as? Int64 ?? 0
+            let response = GobackendFetchLyrics(spotifyId, trackName, artistName, durationMs, &error)
             if let error = error { throw error }
             return response
             
@@ -165,7 +172,8 @@ import Gobackend  // Import Go framework
             let trackName = args["track_name"] as! String
             let artistName = args["artist_name"] as! String
             let filePath = args["file_path"] as? String ?? ""
-            let response = GobackendGetLyricsLRC(spotifyId, trackName, artistName, filePath, &error)
+            let durationMs = args["duration_ms"] as? Int64 ?? 0
+            let response = GobackendGetLyricsLRC(spotifyId, trackName, artistName, filePath, durationMs, &error)
             if let error = error { throw error }
             return response
             
@@ -219,6 +227,13 @@ import Gobackend  // Import Go framework
             if let error = error { throw error }
             return response
 
+        case "getDeezerExtendedMetadata":
+            let args = call.arguments as! [String: Any]
+            let trackId = args["track_id"] as! String
+            let response = GobackendGetDeezerExtendedMetadata(trackId, &error)
+            if let error = error { throw error }
+            return response
+
         case "convertSpotifyToDeezer":
             let args = call.arguments as! [String: Any]
             let resourceType = args["resource_type"] as! String
@@ -249,6 +264,347 @@ import Gobackend  // Import Go framework
             GobackendClearTrackCache()
             return nil
             
+        case "setSpotifyCredentials":
+            let args = call.arguments as! [String: Any]
+            let clientId = args["client_id"] as! String
+            let clientSecret = args["client_secret"] as! String
+            GobackendSetSpotifyAPICredentials(clientId, clientSecret)
+            return nil
+            
+        case "hasSpotifyCredentials":
+            let hasCredentials = GobackendCheckSpotifyCredentials()
+            return hasCredentials
+            
+        // Log methods
+        case "getLogs":
+            let response = GobackendGetLogs()
+            return response
+            
+        case "getLogsSince":
+            let args = call.arguments as! [String: Any]
+            let index = args["index"] as? Int ?? 0
+            let response = GobackendGetLogsSince(Int(index))
+            return response
+            
+        case "clearLogs":
+            GobackendClearLogs()
+            return nil
+            
+        case "getLogCount":
+            let response = GobackendGetLogCount()
+            return response
+            
+        case "setLoggingEnabled":
+            let args = call.arguments as! [String: Any]
+            let enabled = args["enabled"] as? Bool ?? false
+            GobackendSetLoggingEnabled(enabled)
+            return nil
+            
+        // Extension System methods
+        case "initExtensionSystem":
+            let args = call.arguments as! [String: Any]
+            let extensionsDir = args["extensions_dir"] as! String
+            let dataDir = args["data_dir"] as! String
+            GobackendInitExtensionSystem(extensionsDir, dataDir, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "loadExtensionsFromDir":
+            let args = call.arguments as! [String: Any]
+            let dirPath = args["dir_path"] as! String
+            let response = GobackendLoadExtensionsFromDir(dirPath, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "loadExtensionFromPath":
+            let args = call.arguments as! [String: Any]
+            let filePath = args["file_path"] as! String
+            let response = GobackendLoadExtensionFromPath(filePath, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "unloadExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            GobackendUnloadExtensionByID(extensionId, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "getInstalledExtensions":
+            let response = GobackendGetInstalledExtensions(&error)
+            if let error = error { throw error }
+            return response
+            
+        case "setExtensionEnabled":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let enabled = args["enabled"] as? Bool ?? false
+            GobackendSetExtensionEnabledByID(extensionId, enabled, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "setProviderPriority":
+            let args = call.arguments as! [String: Any]
+            let priorityJson = args["priority"] as! String
+            GobackendSetProviderPriorityJSON(priorityJson, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "getProviderPriority":
+            let response = GobackendGetProviderPriorityJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        case "setMetadataProviderPriority":
+            let args = call.arguments as! [String: Any]
+            let priorityJson = args["priority"] as! String
+            GobackendSetMetadataProviderPriorityJSON(priorityJson, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "getMetadataProviderPriority":
+            let response = GobackendGetMetadataProviderPriorityJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        case "getExtensionSettings":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let response = GobackendGetExtensionSettingsJSON(extensionId, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "setExtensionSettings":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let settingsJson = args["settings"] as! String
+            GobackendSetExtensionSettingsJSON(extensionId, settingsJson, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "invokeExtensionAction":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let actionName = args["action"] as! String
+            let response = GobackendInvokeExtensionActionJSON(extensionId, actionName, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "searchTracksWithExtensions":
+            let args = call.arguments as! [String: Any]
+            let query = args["query"] as! String
+            let limit = args["limit"] as? Int ?? 20
+            let response = GobackendSearchTracksWithExtensionsJSON(query, Int(limit), &error)
+            if let error = error { throw error }
+            return response
+            
+        case "downloadWithExtensions":
+            let requestJson = call.arguments as! String
+            let response = GobackendDownloadWithExtensionsJSON(requestJson, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "removeExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            GobackendRemoveExtensionByID(extensionId, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "upgradeExtension":
+            let args = call.arguments as! [String: Any]
+            let filePath = args["file_path"] as! String
+            let response = GobackendUpgradeExtensionFromPath(filePath, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "checkExtensionUpgrade":
+            let args = call.arguments as! [String: Any]
+            let filePath = args["file_path"] as! String
+            let response = GobackendCheckExtensionUpgradeFromPath(filePath, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "cleanupExtensions":
+            GobackendCleanupExtensions()
+            return nil
+            
+        // Extension Auth API
+        case "getExtensionPendingAuth":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let response = GobackendGetExtensionPendingAuthJSON(extensionId, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "setExtensionAuthCode":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let authCode = args["auth_code"] as! String
+            GobackendSetExtensionAuthCodeByID(extensionId, authCode)
+            return nil
+            
+        case "setExtensionTokens":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let accessToken = args["access_token"] as! String
+            let refreshToken = args["refresh_token"] as? String ?? ""
+            let expiresIn = args["expires_in"] as? Int ?? 0
+            GobackendSetExtensionTokensByID(extensionId, accessToken, refreshToken, Int(expiresIn))
+            return nil
+            
+        case "clearExtensionPendingAuth":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            GobackendClearExtensionPendingAuthByID(extensionId)
+            return nil
+            
+        case "isExtensionAuthenticated":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let response = GobackendIsExtensionAuthenticatedByID(extensionId)
+            return response
+            
+        case "getAllPendingAuthRequests":
+            let response = GobackendGetAllPendingAuthRequestsJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        // Extension FFmpeg API
+        case "getPendingFFmpegCommand":
+            let args = call.arguments as! [String: Any]
+            let commandId = args["command_id"] as! String
+            let response = GobackendGetPendingFFmpegCommandJSON(commandId, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "setFFmpegCommandResult":
+            let args = call.arguments as! [String: Any]
+            let commandId = args["command_id"] as! String
+            let success = args["success"] as? Bool ?? false
+            let output = args["output"] as? String ?? ""
+            let errorMsg = args["error"] as? String ?? ""
+            GobackendSetFFmpegCommandResult(commandId, success, output, errorMsg)
+            return nil
+            
+        case "getAllPendingFFmpegCommands":
+            let response = GobackendGetAllPendingFFmpegCommandsJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        // Extension Custom Search API
+        case "customSearchWithExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let query = args["query"] as! String
+            let optionsJson = args["options"] as? String ?? ""
+            let response = GobackendCustomSearchWithExtensionJSON(extensionId, query, optionsJson, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "getSearchProviders":
+            let response = GobackendGetSearchProvidersJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        // Extension URL Handler API
+        case "handleURLWithExtension":
+            let args = call.arguments as! [String: Any]
+            let url = args["url"] as! String
+            let response = GobackendHandleURLWithExtensionJSON(url, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "findURLHandler":
+            let args = call.arguments as! [String: Any]
+            let url = args["url"] as! String
+            let response = GobackendFindURLHandlerJSON(url)
+            return response
+            
+        case "getURLHandlers":
+            let response = GobackendGetURLHandlersJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        case "getAlbumWithExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let albumId = args["album_id"] as! String
+            let response = GobackendGetAlbumWithExtensionJSON(extensionId, albumId, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "getPlaylistWithExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let playlistId = args["playlist_id"] as! String
+            let response = GobackendGetPlaylistWithExtensionJSON(extensionId, playlistId, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "getArtistWithExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let artistId = args["artist_id"] as! String
+            let response = GobackendGetArtistWithExtensionJSON(extensionId, artistId, &error)
+            if let error = error { throw error }
+            return response
+            
+        // Extension Post-Processing API
+        case "runPostProcessing":
+            let args = call.arguments as! [String: Any]
+            let filePath = args["file_path"] as! String
+            let metadataJson = args["metadata"] as? String ?? ""
+            let response = GobackendRunPostProcessingJSON(filePath, metadataJson, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "getPostProcessingProviders":
+            let response = GobackendGetPostProcessingProvidersJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        // Extension Store
+        case "initExtensionStore":
+            let args = call.arguments as! [String: Any]
+            let cacheDir = args["cache_dir"] as! String
+            GobackendInitExtensionStoreJSON(cacheDir, &error)
+            if let error = error { throw error }
+            return nil
+            
+        case "getStoreExtensions":
+            let args = call.arguments as! [String: Any]
+            let forceRefresh = args["force_refresh"] as? Bool ?? false
+            let response = GobackendGetStoreExtensionsJSON(forceRefresh, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "searchStoreExtensions":
+            let args = call.arguments as! [String: Any]
+            let query = args["query"] as? String ?? ""
+            let category = args["category"] as? String ?? ""
+            let response = GobackendSearchStoreExtensionsJSON(query, category, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "getStoreCategories":
+            let response = GobackendGetStoreCategoriesJSON(&error)
+            if let error = error { throw error }
+            return response
+            
+        case "downloadStoreExtension":
+            let args = call.arguments as! [String: Any]
+            let extensionId = args["extension_id"] as! String
+            let destDir = args["dest_dir"] as! String
+            let response = GobackendDownloadStoreExtensionJSON(extensionId, destDir, &error)
+            if let error = error { throw error }
+            return response
+            
+        case "clearStoreCache":
+            GobackendClearStoreCacheJSON(&error)
+            if let error = error { throw error }
+            return nil
+            
         default:
             throw NSError(
                 domain: "SpotiFLAC",

ios/Runner/Info.plist

@@ -4,6 +4,23 @@
 <dict>
 	<key>CFBundleDevelopmentRegion</key>
 	<string>$(DEVELOPMENT_LANGUAGE)</string>
+	<key>CFBundleLocalizations</key>
+	<array>
+		<string>en</string>
+		<string>de</string>
+		<string>es</string>
+		<string>fr</string>
+		<string>hi</string>
+		<string>id</string>
+		<string>ja</string>
+		<string>ko</string>
+		<string>nl</string>
+		<string>pt</string>
+		<string>ru</string>
+		<string>zh</string>
+		<string>zh-Hans</string>
+		<string>zh-Hant</string>
+	</array>
 	<key>CFBundleDisplayName</key>
 	<string>SpotiFLAC</string>
 	<key>CFBundleExecutable</key>

l10n.yaml

@@ -0,0 +1,6 @@
+arb-dir: lib/l10n/arb
+template-arb-file: app_en.arb
+output-localization-file: app_localizations.dart
+output-class: AppLocalizations
+output-dir: lib/l10n
+nullable-getter: false

lib/app.dart

@@ -1,13 +1,14 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:go_router/go_router.dart';
 import 'package:spotiflac_android/screens/main_shell.dart';
 import 'package:spotiflac_android/screens/setup_screen.dart';
 import 'package:spotiflac_android/providers/settings_provider.dart';
 import 'package:spotiflac_android/theme/dynamic_color_wrapper.dart';
+import 'package:spotiflac_android/l10n/app_localizations.dart';
 
 final _routerProvider = Provider<GoRouter>((ref) {
-  // Only watch isFirstLaunch to prevent router rebuild on other settings changes
   final isFirstLaunch = ref.watch(settingsProvider.select((s) => s.isFirstLaunch));
   
   return GoRouter(
@@ -31,6 +32,17 @@ class SpotiFLACApp extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final router = ref.watch(_routerProvider);
+    final localeString = ref.watch(settingsProvider.select((s) => s.locale));
+    
+    Locale? locale;
+    if (localeString != 'system') {
+      if (localeString.contains('_')) {
+        final parts = localeString.split('_');
+        locale = Locale(parts[0], parts[1]);
+      } else {
+        locale = Locale(localeString);
+      }
+    }
     
     return DynamicColorWrapper(
       builder: (lightTheme, darkTheme, themeMode) {
@@ -43,6 +55,14 @@ class SpotiFLACApp extends ConsumerWidget {
           themeAnimationDuration: const Duration(milliseconds: 300),
           themeAnimationCurve: Curves.easeInOut,
           routerConfig: router,
+          locale: locale,
+          localizationsDelegates: const [
+            AppLocalizations.delegate,
+            GlobalMaterialLocalizations.delegate,
+            GlobalWidgetsLocalizations.delegate,
+            GlobalCupertinoLocalizations.delegate,
+          ],
+          supportedLocales: AppLocalizations.supportedLocales,
         );
       },
     );

lib/constants/app_info.dart

@@ -1,8 +1,8 @@
 /// App version and info constants
 /// Update version here only - all other files will reference this
 class AppInfo {
-  static const String version = '2.2.0';
+  static const String version = '3.1.3';
-  static const String buildNumber = '46';
+  static const String buildNumber = '62';
   static const String fullVersion = '$version+$buildNumber';
   
   

lib/l10n/arb/app_id.arb

@@ -0,0 +1,687 @@
+{
+  "@@locale": "id",
+  "@@last_modified": "2026-01-16",
+
+  "appName": "SpotiFLAC",
+  "appDescription": "Unduh lagu Spotify dalam kualitas lossless dari Tidal, Qobuz, dan Amazon Music.",
+
+  "navHome": "Beranda",
+  "navHistory": "Riwayat",
+  "navSettings": "Pengaturan",
+  "navStore": "Toko",
+
+  "homeTitle": "Beranda",
+  "homeSearchHint": "Tempel URL Spotify atau cari...",
+  "homeSearchHintExtension": "Cari dengan {extensionName}...",
+  "homeSubtitle": "Tempel link Spotify atau cari berdasarkan nama",
+  "homeSupports": "Mendukung: URL Track, Album, Playlist, Artis",
+  "homeRecent": "Terbaru",
+
+  "historyTitle": "Riwayat",
+  "historyDownloading": "Mengunduh ({count})",
+  "historyDownloaded": "Terunduh",
+  "historyFilterAll": "Semua",
+  "historyFilterAlbums": "Album",
+  "historyFilterSingles": "Single",
+  "historyTracksCount": "{count, plural, =1{1 lagu} other{{count} lagu}}",
+  "historyAlbumsCount": "{count, plural, =1{1 album} other{{count} album}}",
+  "historyNoDownloads": "Tidak ada riwayat unduhan",
+  "historyNoDownloadsSubtitle": "Lagu yang diunduh akan muncul di sini",
+  "historyNoAlbums": "Tidak ada unduhan album",
+  "historyNoAlbumsSubtitle": "Unduh beberapa lagu dari album untuk melihatnya di sini",
+  "historyNoSingles": "Tidak ada unduhan single",
+  "historyNoSinglesSubtitle": "Unduhan lagu satuan akan muncul di sini",
+
+  "settingsTitle": "Pengaturan",
+  "settingsDownload": "Unduhan",
+  "settingsAppearance": "Tampilan",
+  "settingsOptions": "Opsi",
+  "settingsExtensions": "Ekstensi",
+  "settingsAbout": "Tentang",
+
+  "downloadTitle": "Unduhan",
+  "downloadLocation": "Lokasi Unduhan",
+  "downloadLocationSubtitle": "Pilih tempat menyimpan file",
+  "downloadLocationDefault": "Lokasi default",
+  "downloadDefaultService": "Layanan Default",
+  "downloadDefaultServiceSubtitle": "Layanan yang digunakan untuk unduhan",
+  "downloadDefaultQuality": "Kualitas Default",
+  "downloadAskQuality": "Tanya Kualitas Sebelum Unduh",
+  "downloadAskQualitySubtitle": "Tampilkan pemilih kualitas untuk setiap unduhan",
+  "downloadFilenameFormat": "Format Nama File",
+  "downloadFolderOrganization": "Organisasi Folder",
+  "downloadSeparateSingles": "Pisahkan Single",
+  "downloadSeparateSinglesSubtitle": "Letakkan lagu satuan di folder terpisah",
+
+  "qualityBest": "Terbaik",
+  "qualityFlac": "FLAC",
+  "quality320": "320 kbps",
+  "quality128": "128 kbps",
+
+  "appearanceTitle": "Tampilan",
+  "appearanceTheme": "Tema",
+  "appearanceThemeSystem": "Sistem",
+  "appearanceThemeLight": "Terang",
+  "appearanceThemeDark": "Gelap",
+  "appearanceDynamicColor": "Warna Dinamis",
+  "appearanceDynamicColorSubtitle": "Gunakan warna dari wallpaper Anda",
+  "appearanceAccentColor": "Warna Aksen",
+  "appearanceHistoryView": "Tampilan Riwayat",
+  "appearanceHistoryViewList": "Daftar",
+  "appearanceHistoryViewGrid": "Grid",
+
+  "optionsTitle": "Opsi",
+  "optionsSearchSource": "Sumber Pencarian",
+  "optionsPrimaryProvider": "Provider Utama",
+  "optionsPrimaryProviderSubtitle": "Layanan yang digunakan saat mencari berdasarkan nama lagu.",
+  "optionsUsingExtension": "Menggunakan ekstensi: {extensionName}",
+  "optionsSwitchBack": "Ketuk Deezer atau Spotify untuk beralih dari ekstensi",
+  "optionsAutoFallback": "Auto Fallback",
+  "optionsAutoFallbackSubtitle": "Coba layanan lain jika unduhan gagal",
+  "optionsUseExtensionProviders": "Gunakan Provider Ekstensi",
+  "optionsUseExtensionProvidersOn": "Ekstensi akan dicoba terlebih dahulu",
+  "optionsUseExtensionProvidersOff": "Hanya menggunakan provider bawaan",
+  "optionsEmbedLyrics": "Sematkan Lirik",
+  "optionsEmbedLyricsSubtitle": "Sematkan lirik sinkron ke file FLAC",
+  "optionsMaxQualityCover": "Cover Kualitas Maksimal",
+  "optionsMaxQualityCoverSubtitle": "Unduh cover art resolusi tertinggi",
+  "optionsConcurrentDownloads": "Unduhan Bersamaan",
+  "optionsConcurrentSequential": "Berurutan (1 per waktu)",
+  "optionsConcurrentParallel": "{count} unduhan paralel",
+  "optionsConcurrentWarning": "Unduhan paralel dapat memicu pembatasan rate",
+  "optionsExtensionStore": "Toko Ekstensi",
+  "optionsExtensionStoreSubtitle": "Tampilkan tab Toko di navigasi",
+  "optionsCheckUpdates": "Periksa Pembaruan",
+  "optionsCheckUpdatesSubtitle": "Beritahu saat versi baru tersedia",
+  "optionsUpdateChannel": "Saluran Pembaruan",
+  "optionsUpdateChannelStable": "Hanya rilis stabil",
+  "optionsUpdateChannelPreview": "Dapatkan rilis preview",
+  "optionsUpdateChannelWarning": "Preview mungkin mengandung bug atau fitur belum lengkap",
+  "optionsClearHistory": "Hapus Riwayat Unduhan",
+  "optionsClearHistorySubtitle": "Hapus semua lagu dari riwayat",
+  "optionsDetailedLogging": "Log Detail",
+  "optionsDetailedLoggingOn": "Log detail sedang direkam",
+  "optionsDetailedLoggingOff": "Aktifkan untuk laporan bug",
+  "optionsSpotifyCredentials": "Kredensial Spotify",
+  "optionsSpotifyCredentialsConfigured": "Client ID: {clientId}...",
+  "optionsSpotifyCredentialsRequired": "Diperlukan - ketuk untuk mengatur",
+  "optionsSpotifyWarning": "Spotify memerlukan kredensial API Anda sendiri. Dapatkan gratis dari developer.spotify.com",
+
+  "extensionsTitle": "Ekstensi",
+  "extensionsInstalled": "Ekstensi Terpasang",
+  "extensionsNone": "Tidak ada ekstensi terpasang",
+  "extensionsNoneSubtitle": "Pasang ekstensi dari tab Toko",
+  "extensionsEnabled": "Aktif",
+  "extensionsDisabled": "Nonaktif",
+  "extensionsVersion": "Versi {version}",
+  "extensionsAuthor": "oleh {author}",
+  "extensionsUninstall": "Copot",
+  "extensionsSetAsSearch": "Jadikan Provider Pencarian",
+
+  "storeTitle": "Toko Ekstensi",
+  "storeSearch": "Cari ekstensi...",
+  "storeInstall": "Pasang",
+  "storeInstalled": "Terpasang",
+  "storeUpdate": "Perbarui",
+
+  "aboutTitle": "Tentang",
+  "aboutContributors": "Kontributor",
+  "aboutMobileDeveloper": "Pengembang versi mobile",
+  "aboutOriginalCreator": "Pencipta SpotiFLAC asli",
+  "aboutLogoArtist": "Seniman berbakat yang membuat logo aplikasi kami yang indah!",
+  "aboutSpecialThanks": "Terima Kasih Khusus",
+  "aboutLinks": "Tautan",
+  "aboutMobileSource": "Kode sumber mobile",
+  "aboutPCSource": "Kode sumber PC",
+  "aboutReportIssue": "Laporkan masalah",
+  "aboutReportIssueSubtitle": "Laporkan masalah yang Anda temui",
+  "aboutFeatureRequest": "Permintaan fitur",
+  "aboutFeatureRequestSubtitle": "Sarankan fitur baru untuk aplikasi",
+  "aboutSupport": "Dukungan",
+  "aboutBuyMeCoffee": "Traktir saya kopi",
+  "aboutBuyMeCoffeeSubtitle": "Dukung pengembangan di Ko-fi",
+  "aboutApp": "Aplikasi",
+  "aboutVersion": "Versi",
+
+  "albumTitle": "Album",
+  "albumTracks": "{count, plural, =1{1 lagu} other{{count} lagu}}",
+  "albumDownloadAll": "Unduh Semua",
+  "albumDownloadRemaining": "Unduh Sisanya",
+
+  "playlistTitle": "Playlist",
+  "artistTitle": "Artis",
+  "artistAlbums": "Album",
+  "artistSingles": "Single & EP",
+
+  "trackMetadataTitle": "Info Lagu",
+  "trackMetadataArtist": "Artis",
+  "trackMetadataAlbum": "Album",
+  "trackMetadataDuration": "Durasi",
+  "trackMetadataQuality": "Kualitas",
+  "trackMetadataPath": "Lokasi File",
+  "trackMetadataDownloadedAt": "Diunduh",
+  "trackMetadataService": "Layanan",
+  "trackMetadataPlay": "Putar",
+  "trackMetadataShare": "Bagikan",
+  "trackMetadataDelete": "Hapus",
+  "trackMetadataRedownload": "Unduh ulang",
+  "trackMetadataOpenFolder": "Buka Folder",
+
+  "setupTitle": "Selamat Datang di SpotiFLAC",
+  "setupSubtitle": "Mari mulai pengaturan",
+  "setupStoragePermission": "Izin Penyimpanan",
+  "setupStoragePermissionSubtitle": "Diperlukan untuk menyimpan file unduhan",
+  "setupStoragePermissionGranted": "Izin diberikan",
+  "setupStoragePermissionDenied": "Izin ditolak",
+  "setupGrantPermission": "Berikan Izin",
+  "setupDownloadLocation": "Lokasi Unduhan",
+  "setupChooseFolder": "Pilih Folder",
+  "setupContinue": "Lanjutkan",
+  "setupSkip": "Lewati untuk sekarang",
+
+  "dialogCancel": "Batal",
+  "dialogOk": "OK",
+  "dialogSave": "Simpan",
+  "dialogDelete": "Hapus",
+  "dialogRetry": "Coba Lagi",
+  "dialogClose": "Tutup",
+  "dialogYes": "Ya",
+  "dialogNo": "Tidak",
+  "dialogClear": "Hapus",
+  "dialogConfirm": "Konfirmasi",
+  "dialogDone": "Selesai",
+
+  "dialogClearHistoryTitle": "Hapus Riwayat",
+  "dialogClearHistoryMessage": "Apakah Anda yakin ingin menghapus semua riwayat unduhan? Ini tidak dapat dibatalkan.",
+  "dialogDeleteSelectedTitle": "Hapus yang Dipilih",
+  "dialogDeleteSelectedMessage": "Hapus {count} {count, plural, =1{lagu} other{lagu}} dari riwayat?\n\nIni juga akan menghapus file dari penyimpanan.",
+  "dialogImportPlaylistTitle": "Impor Playlist",
+  "dialogImportPlaylistMessage": "Ditemukan {count} lagu di CSV. Tambahkan ke antrian unduhan?",
+
+  "snackbarAddedToQueue": "Menambahkan \"{trackName}\" ke antrian",
+  "snackbarAddedTracksToQueue": "Menambahkan {count} lagu ke antrian",
+  "snackbarAlreadyDownloaded": "\"{trackName}\" sudah diunduh",
+  "snackbarHistoryCleared": "Riwayat dihapus",
+  "snackbarCredentialsSaved": "Kredensial disimpan",
+  "snackbarCredentialsCleared": "Kredensial dihapus",
+  "snackbarDeletedTracks": "Menghapus {count} {count, plural, =1{lagu} other{lagu}}",
+  "snackbarCannotOpenFile": "Tidak dapat membuka file: {error}",
+  "snackbarFillAllFields": "Harap isi semua field",
+  "snackbarViewQueue": "Lihat Antrian",
+
+  "errorRateLimited": "Dibatasi",
+  "errorRateLimitedMessage": "Terlalu banyak permintaan. Harap tunggu sebentar sebelum mencari lagi.",
+  "errorFailedToLoad": "Gagal memuat {item}",
+  "errorNoTracksFound": "Tidak ada lagu ditemukan",
+  "errorMissingExtensionSource": "Tidak dapat memuat {item}: sumber ekstensi tidak ada",
+
+  "statusQueued": "Mengantri",
+  "statusDownloading": "Mengunduh",
+  "statusFinalizing": "Menyelesaikan",
+  "statusCompleted": "Selesai",
+  "statusFailed": "Gagal",
+  "statusSkipped": "Dilewati",
+  "statusPaused": "Dijeda",
+
+  "actionPause": "Jeda",
+  "actionResume": "Lanjutkan",
+  "actionCancel": "Batal",
+  "actionStop": "Hentikan",
+  "actionSelect": "Pilih",
+  "actionSelectAll": "Pilih Semua",
+  "actionDeselect": "Batal Pilih",
+  "actionPaste": "Tempel",
+  "actionImportCsv": "Impor CSV",
+  "actionRemoveCredentials": "Hapus Kredensial",
+  "actionSaveCredentials": "Simpan Kredensial",
+
+  "selectionSelected": "{count} dipilih",
+  "selectionAllSelected": "Semua lagu dipilih",
+  "selectionTapToSelect": "Ketuk lagu untuk memilih",
+  "selectionDeleteTracks": "Hapus {count} {count, plural, =1{lagu} other{lagu}}",
+  "selectionSelectToDelete": "Pilih lagu untuk dihapus",
+
+  "progressFetchingMetadata": "Mengambil metadata... {current}/{total}",
+  "progressReadingCsv": "Membaca CSV...",
+
+  "searchSongs": "Lagu",
+  "searchArtists": "Artis",
+  "searchAlbums": "Album",
+  "searchPlaylists": "Playlist",
+
+  "tooltipPlay": "Putar",
+  "tooltipCancel": "Batal",
+  "tooltipStop": "Hentikan",
+  "tooltipRetry": "Coba Lagi",
+  "tooltipRemove": "Hapus",
+  "tooltipClear": "Hapus",
+  "tooltipPaste": "Tempel",
+
+  "filenameFormat": "Format Nama File",
+  "filenameFormatPreview": "Pratinjau: {preview}",
+  "folderOrganization": "Organisasi Folder",
+  "folderOrganizationNone": "Tanpa organisasi",
+  "folderOrganizationByArtist": "Berdasarkan Artis",
+  "folderOrganizationByAlbum": "Berdasarkan Album",
+  "folderOrganizationByArtistAlbum": "Artis/Album",
+
+  "updateAvailable": "Pembaruan Tersedia",
+  "updateNewVersion": "Versi {version} tersedia",
+  "updateDownload": "Unduh",
+  "updateLater": "Nanti",
+  "updateChangelog": "Log Perubahan",
+
+  "providerPriority": "Prioritas Provider",
+  "providerPrioritySubtitle": "Seret untuk mengatur ulang provider unduhan",
+  "metadataProviderPriority": "Prioritas Provider Metadata",
+  "metadataProviderPrioritySubtitle": "Urutan yang digunakan saat mengambil metadata lagu",
+
+  "logTitle": "Log",
+  "logCopy": "Salin Log",
+  "logClear": "Hapus Log",
+  "logShare": "Bagikan Log",
+  "logEmpty": "Belum ada log",
+  "logCopied": "Log disalin ke clipboard",
+
+  "credentialsTitle": "Kredensial Spotify",
+  "credentialsDescription": "Masukkan Client ID dan Secret Anda untuk menggunakan kuota aplikasi Spotify Anda sendiri.",
+  "credentialsClientId": "Client ID",
+  "credentialsClientIdHint": "Tempel Client ID",
+  "credentialsClientSecret": "Client Secret",
+  "credentialsClientSecretHint": "Tempel Client Secret",
+
+  "channelStable": "Stabil",
+  "channelPreview": "Preview",
+
+  "sectionSearchSource": "Sumber Pencarian",
+  "sectionDownload": "Unduhan",
+  "sectionPerformance": "Performa",
+  "sectionApp": "Aplikasi",
+  "sectionData": "Data",
+  "sectionDebug": "Debug",
+  "sectionService": "Layanan",
+  "sectionAudioQuality": "Kualitas Audio",
+  "sectionFileSettings": "Pengaturan File",
+  "sectionColor": "Warna",
+  "sectionTheme": "Tema",
+  "sectionLayout": "Tata Letak",
+  "sectionLanguage": "Bahasa",
+
+  "appearanceLanguage": "Bahasa Aplikasi",
+  "appearanceLanguageSubtitle": "Pilih bahasa yang kamu inginkan",
+  "languageSystem": "Bawaan Sistem",
+  "languageEnglish": "English",
+  "languageIndonesian": "Bahasa Indonesia",
+
+  "settingsAppearanceSubtitle": "Tema, warna, tampilan",
+  "settingsDownloadSubtitle": "Layanan, kualitas, format nama file",
+  "settingsOptionsSubtitle": "Fallback, lirik, cover art, pembaruan",
+  "settingsExtensionsSubtitle": "Kelola provider unduhan",
+  "settingsLogsSubtitle": "Lihat log aplikasi untuk debugging",
+
+  "loadingSharedLink": "Memuat link yang dibagikan...",
+  "pressBackAgainToExit": "Tekan kembali sekali lagi untuk keluar",
+
+  "artistReleases": "{count, plural, =1{1 rilis} other{{count} rilis}}",
+  "artistCompilations": "Kompilasi",
+  "artistPopular": "Populer",
+  "artistMonthlyListeners": "{count} pendengar bulanan",
+
+  "tracksHeader": "Lagu",
+  "downloadAllCount": "Unduh Semua ({count})",
+  "tracksCount": "{count, plural, =1{1 lagu} other{{count} lagu}}",
+
+  "setupStorageAccessRequired": "Akses Penyimpanan Diperlukan",
+  "setupStorageAccessMessage": "SpotiFLAC membutuhkan izin \"Akses semua file\" untuk menyimpan file musik ke folder pilihan Anda.",
+  "setupStorageAccessMessageAndroid11": "Android 11+ memerlukan izin \"Akses semua file\" untuk menyimpan file ke folder unduhan pilihan Anda.",
+  "setupOpenSettings": "Buka Pengaturan",
+  "setupPermissionDeniedMessage": "Izin ditolak. Harap berikan semua izin untuk melanjutkan.",
+  "setupPermissionRequired": "Izin {permissionType} Diperlukan",
+  "setupPermissionRequiredMessage": "Izin {permissionType} diperlukan untuk pengalaman terbaik. Anda dapat mengubahnya nanti di Pengaturan.",
+  "setupSelectDownloadFolder": "Pilih Folder Unduhan",
+  "setupUseDefaultFolder": "Gunakan Folder Default?",
+  "setupNoFolderSelected": "Tidak ada folder dipilih. Apakah Anda ingin menggunakan folder Musik default?",
+  "setupUseDefault": "Gunakan Default",
+  "setupDownloadLocationTitle": "Lokasi Unduhan",
+  "setupDownloadLocationIosMessage": "Di iOS, unduhan disimpan ke folder Documents aplikasi. Anda dapat mengaksesnya melalui aplikasi Files.",
+  "setupAppDocumentsFolder": "Folder Documents Aplikasi",
+  "setupAppDocumentsFolderSubtitle": "Direkomendasikan - dapat diakses via aplikasi Files",
+  "setupChooseFromFiles": "Pilih dari Files",
+  "setupChooseFromFilesSubtitle": "Pilih lokasi iCloud atau lainnya",
+  "setupIosEmptyFolderWarning": "Batasan iOS: Folder kosong tidak dapat dipilih. Pilih folder dengan minimal satu file.",
+  "setupDownloadInFlac": "Unduh lagu Spotify dalam format FLAC",
+  "setupStepStorage": "Penyimpanan",
+  "setupStepNotification": "Notifikasi",
+  "setupStepFolder": "Folder",
+  "setupStepSpotify": "Spotify",
+  "setupStepPermission": "Izin",
+  "setupStorageGranted": "Izin Penyimpanan Diberikan!",
+  "setupStorageRequired": "Izin Penyimpanan Diperlukan",
+  "setupStorageDescription": "SpotiFLAC membutuhkan izin penyimpanan untuk menyimpan file musik yang diunduh.",
+  "setupNotificationGranted": "Izin Notifikasi Diberikan!",
+  "setupNotificationEnable": "Aktifkan Notifikasi",
+  "setupNotificationDescription": "Dapatkan pemberitahuan saat unduhan selesai atau membutuhkan perhatian.",
+  "setupFolderSelected": "Folder Unduhan Dipilih!",
+  "setupFolderChoose": "Pilih Folder Unduhan",
+  "setupFolderDescription": "Pilih folder tempat musik yang diunduh akan disimpan.",
+  "setupChangeFolder": "Ubah Folder",
+  "setupSelectFolder": "Pilih Folder",
+  "setupSpotifyApiOptional": "Spotify API (Opsional)",
+  "setupSpotifyApiDescription": "Tambahkan kredensial Spotify API untuk hasil pencarian lebih baik dan akses ke konten eksklusif Spotify.",
+  "setupUseSpotifyApi": "Gunakan Spotify API",
+  "setupEnterCredentialsBelow": "Masukkan kredensial Anda di bawah",
+  "setupUsingDeezer": "Menggunakan Deezer (tidak perlu akun)",
+  "setupEnterClientId": "Masukkan Spotify Client ID",
+  "setupEnterClientSecret": "Masukkan Spotify Client Secret",
+  "setupGetFreeCredentials": "Dapatkan kredensial API gratis dari Spotify Developer Dashboard.",
+  "setupEnableNotifications": "Aktifkan Notifikasi",
+
+  "dialogImport": "Impor",
+  "dialogDiscard": "Buang",
+  "dialogRemove": "Hapus",
+  "dialogUninstall": "Copot",
+  "dialogDiscardChanges": "Buang Perubahan?",
+  "dialogUnsavedChanges": "Anda memiliki perubahan yang belum disimpan. Apakah Anda ingin membuangnya?",
+  "dialogDownloadFailed": "Unduhan Gagal",
+  "dialogTrackLabel": "Lagu:",
+  "dialogArtistLabel": "Artis:",
+  "dialogErrorLabel": "Error:",
+  "dialogClearAll": "Hapus Semua",
+  "dialogClearAllDownloads": "Apakah Anda yakin ingin menghapus semua unduhan?",
+  "dialogRemoveFromDevice": "Hapus dari perangkat?",
+  "dialogRemoveExtension": "Hapus Ekstensi",
+  "dialogRemoveExtensionMessage": "Apakah Anda yakin ingin menghapus ekstensi ini? Tindakan ini tidak dapat dibatalkan.",
+  "dialogUninstallExtension": "Copot Ekstensi?",
+  "dialogUninstallExtensionMessage": "Apakah Anda yakin ingin menghapus {extensionName}?",
+
+  "snackbarFailedToLoad": "Gagal memuat: {error}",
+  "snackbarUrlCopied": "URL {platform} disalin ke clipboard",
+  "snackbarFileNotFound": "File tidak ditemukan",
+  "snackbarSelectExtFile": "Harap pilih file .spotiflac-ext",
+  "snackbarProviderPrioritySaved": "Prioritas provider disimpan",
+  "snackbarMetadataProviderSaved": "Prioritas provider metadata disimpan",
+  "snackbarExtensionInstalled": "{extensionName} terpasang.",
+  "snackbarExtensionUpdated": "{extensionName} diperbarui.",
+  "snackbarFailedToInstall": "Gagal memasang ekstensi",
+  "snackbarFailedToUpdate": "Gagal memperbarui ekstensi",
+
+  "storeFilterAll": "Semua",
+  "storeFilterMetadata": "Metadata",
+  "storeFilterDownload": "Unduhan",
+  "storeFilterUtility": "Utilitas",
+  "storeFilterLyrics": "Lirik",
+  "storeFilterIntegration": "Integrasi",
+  "storeClearFilters": "Hapus filter",
+  "storeNoResults": "Tidak ada ekstensi ditemukan",
+
+  "extensionProviderPriority": "Prioritas Provider",
+  "extensionInstallButton": "Pasang Ekstensi",
+  "extensionDefaultProvider": "Default (Deezer/Spotify)",
+  "extensionDefaultProviderSubtitle": "Gunakan pencarian bawaan",
+  "extensionAuthor": "Pembuat",
+  "extensionId": "ID",
+  "extensionError": "Error",
+  "extensionCapabilities": "Kemampuan",
+  "extensionMetadataProvider": "Provider Metadata",
+  "extensionDownloadProvider": "Provider Unduhan",
+  "extensionLyricsProvider": "Provider Lirik",
+  "extensionUrlHandler": "Penanganan URL",
+  "extensionQualityOptions": "Opsi Kualitas",
+  "extensionPostProcessingHooks": "Hook Pasca-Pemrosesan",
+  "extensionPermissions": "Izin",
+  "extensionSettings": "Pengaturan",
+  "extensionRemoveButton": "Hapus Ekstensi",
+  "extensionUpdated": "Diperbarui",
+  "extensionMinAppVersion": "Versi App Minimum",
+
+  "qualityFlacLossless": "FLAC Lossless",
+  "qualityFlacLosslessSubtitle": "16-bit / 44.1kHz",
+  "qualityHiResFlac": "Hi-Res FLAC",
+  "qualityHiResFlacSubtitle": "24-bit / hingga 96kHz",
+  "qualityHiResFlacMax": "Hi-Res FLAC Max",
+  "qualityHiResFlacMaxSubtitle": "24-bit / hingga 192kHz",
+  "qualityMp3": "MP3",
+  "qualityMp3Subtitle": "320kbps (konversi dari FLAC)",
+  "enableMp3Option": "Aktifkan Opsi MP3",
+  "enableMp3OptionSubtitleOn": "Opsi kualitas MP3 tersedia",
+  "enableMp3OptionSubtitleOff": "Unduh FLAC lalu konversi ke MP3 320kbps",
+  "qualityNote": "Kualitas sebenarnya tergantung ketersediaan lagu dari layanan",
+
+  "downloadAskBeforeDownload": "Tanya Sebelum Unduh",
+  "downloadDirectory": "Direktori Unduhan",
+  "downloadSeparateSinglesFolder": "Folder Singles Terpisah",
+  "downloadAlbumFolderStructure": "Struktur Folder Album",
+  "downloadSaveFormat": "Simpan Format",
+  "downloadSelectService": "Pilih Layanan",
+  "downloadSelectQuality": "Pilih Kualitas",
+  "downloadFrom": "Unduh Dari",
+  "downloadDefaultQualityLabel": "Kualitas Default",
+  "downloadBestAvailable": "Terbaik tersedia",
+
+  "folderNone": "Tidak ada",
+  "folderNoneSubtitle": "Simpan semua file langsung ke folder unduhan",
+  "folderArtist": "Artis",
+  "folderArtistSubtitle": "Nama Artis/namafile",
+  "folderAlbum": "Album",
+  "folderAlbumSubtitle": "Nama Album/namafile",
+  "folderArtistAlbum": "Artis/Album",
+  "folderArtistAlbumSubtitle": "Nama Artis/Nama Album/namafile",
+
+  "serviceTidal": "Tidal",
+  "serviceQobuz": "Qobuz",
+  "serviceAmazon": "Amazon",
+  "serviceDeezer": "Deezer",
+  "serviceSpotify": "Spotify",
+
+  "logSearchHint": "Cari log...",
+  "logFilterLevel": "Level",
+  "logFilterSection": "Filter",
+  "logShareLogs": "Bagikan log",
+  "logClearLogs": "Hapus log",
+  "logClearLogsTitle": "Hapus Log",
+  "logClearLogsMessage": "Apakah Anda yakin ingin menghapus semua log?",
+  "logIspBlocking": "PEMBLOKIRAN ISP TERDETEKSI",
+  "logRateLimited": "DIBATASI",
+  "logNetworkError": "ERROR JARINGAN",
+  "logTrackNotFound": "LAGU TIDAK DITEMUKAN",
+
+  "appearanceAmoledDark": "AMOLED Gelap",
+  "appearanceAmoledDarkSubtitle": "Latar belakang hitam murni",
+  "appearanceChooseAccentColor": "Pilih Warna Aksen",
+  "appearanceChooseTheme": "Mode Tema",
+
+  "updateStartingDownload": "Memulai unduhan...",
+  "updateDownloadFailed": "Unduhan gagal",
+  "updateFailedMessage": "Gagal mengunduh pembaruan",
+  "updateNewVersionReady": "Versi baru sudah siap",
+  "updateCurrent": "Saat ini",
+  "updateNew": "Baru",
+  "updateDownloading": "Mengunduh...",
+  "updateWhatsNew": "Yang Baru",
+  "updateDownloadInstall": "Unduh & Pasang",
+  "updateDontRemind": "Jangan ingatkan",
+
+  "trackCopyFilePath": "Salin lokasi file",
+  "trackRemoveFromDevice": "Hapus dari perangkat",
+  "trackLoadLyrics": "Muat Lirik",
+
+  "dateToday": "Hari ini",
+  "dateYesterday": "Kemarin",
+  "dateDaysAgo": "{count} hari lalu",
+  "dateWeeksAgo": "{count} minggu lalu",
+  "dateMonthsAgo": "{count} bulan lalu",
+
+  "concurrentSequential": "Berurutan",
+  "concurrentParallel2": "2 Paralel",
+  "concurrentParallel3": "3 Paralel",
+
+  "filenameAvailablePlaceholders": "Placeholder yang tersedia:",
+  "filenameHint": "{artist} - {title}",
+
+  "tapToSeeError": "Ketuk untuk melihat detail error",
+
+  "setupProceedToNextStep": "Anda dapat melanjutkan ke langkah berikutnya.",
+  "setupNotificationProgressDescription": "Anda akan menerima notifikasi progres unduhan.",
+  "setupNotificationBackgroundDescription": "Dapatkan notifikasi tentang progres dan penyelesaian unduhan. Ini membantu Anda melacak unduhan saat aplikasi di latar belakang.",
+  "setupSkipForNow": "Lewati untuk sekarang",
+  "setupBack": "Kembali",
+  "setupNext": "Lanjut",
+  "setupGetStarted": "Mulai",
+  "setupSkipAndStart": "Lewati & Mulai",
+  "setupAllowAccessToManageFiles": "Harap aktifkan \"Izinkan akses untuk mengelola semua file\" di layar berikutnya.",
+  "setupGetCredentialsFromSpotify": "Dapatkan kredensial dari developer.spotify.com",
+
+  "trackMetadata": "Metadata",
+  "trackFileInfo": "Info File",
+  "trackLyrics": "Lirik",
+  "trackFileNotFound": "File tidak ditemukan",
+  "trackOpenInDeezer": "Buka di Deezer",
+  "trackOpenInSpotify": "Buka di Spotify",
+  "trackTrackName": "Nama lagu",
+  "trackArtist": "Artis",
+  "trackAlbumArtist": "Artis album",
+  "trackAlbum": "Album",
+  "trackTrackNumber": "Nomor lagu",
+  "trackDiscNumber": "Nomor disc",
+  "trackDuration": "Durasi",
+  "trackAudioQuality": "Kualitas audio",
+  "trackReleaseDate": "Tanggal rilis",
+  "trackDownloaded": "Diunduh",
+  "trackCopyLyrics": "Salin lirik",
+  "trackLyricsNotAvailable": "Lirik tidak tersedia untuk lagu ini",
+  "trackLyricsTimeout": "Permintaan timeout. Coba lagi nanti.",
+  "trackLyricsLoadFailed": "Gagal memuat lirik",
+  "trackCopiedToClipboard": "Disalin ke clipboard",
+  "trackDeleteConfirmTitle": "Hapus dari perangkat?",
+  "trackDeleteConfirmMessage": "Ini akan menghapus file unduhan secara permanen dan menghapusnya dari riwayat Anda.",
+  "trackCannotOpen": "Tidak dapat membuka: {message}",
+
+  "logFilterBySeverity": "Filter log berdasarkan tingkat keparahan",
+  "logNoLogsYet": "Belum ada log",
+  "logNoLogsYetSubtitle": "Log akan muncul di sini saat Anda menggunakan aplikasi",
+  "logIssueSummary": "Ringkasan Masalah",
+  "logIspBlockingDescription": "ISP Anda mungkin memblokir akses ke layanan unduhan",
+  "logIspBlockingSuggestion": "Coba gunakan VPN atau ubah DNS ke 1.1.1.1 atau 8.8.8.8",
+  "logRateLimitedDescription": "Terlalu banyak permintaan ke layanan",
+  "logRateLimitedSuggestion": "Tunggu beberapa menit sebelum mencoba lagi",
+  "logNetworkErrorDescription": "Masalah koneksi terdeteksi",
+  "logNetworkErrorSuggestion": "Periksa koneksi internet Anda",
+  "logTrackNotFoundDescription": "Beberapa lagu tidak dapat ditemukan di layanan unduhan",
+  "logTrackNotFoundSuggestion": "Lagu mungkin tidak tersedia dalam kualitas lossless",
+  "logTotalErrors": "Total error: {count}",
+  "logAffected": "Terpengaruh: {domains}",
+  "logEntriesFiltered": "Entri ({count} difilter)",
+  "logEntries": "Entri ({count})",
+
+  "extensionsProviderPrioritySection": "Prioritas Provider",
+  "extensionsInstalledSection": "Ekstensi Terpasang",
+  "extensionsNoExtensions": "Tidak ada ekstensi terpasang",
+  "extensionsNoExtensionsSubtitle": "Pasang file .spotiflac-ext untuk menambahkan provider baru",
+  "extensionsInstallButton": "Pasang Ekstensi",
+  "extensionsInfoTip": "Ekstensi dapat menambahkan provider metadata dan unduhan baru. Hanya pasang ekstensi dari sumber terpercaya.",
+  "extensionsInstalledSuccess": "Ekstensi berhasil dipasang",
+  "extensionsDownloadPriority": "Prioritas Unduhan",
+  "extensionsDownloadPrioritySubtitle": "Atur urutan layanan unduhan",
+  "extensionsNoDownloadProvider": "Tidak ada ekstensi dengan provider unduhan",
+  "extensionsMetadataPriority": "Prioritas Metadata",
+  "extensionsMetadataPrioritySubtitle": "Atur urutan sumber pencarian & metadata",
+  "extensionsNoMetadataProvider": "Tidak ada ekstensi dengan provider metadata",
+  "extensionsSearchProvider": "Provider Pencarian",
+  "extensionsNoCustomSearch": "Tidak ada ekstensi dengan pencarian kustom",
+  "extensionsSearchProviderDescription": "Pilih layanan yang digunakan untuk mencari lagu",
+  "extensionsCustomSearch": "Pencarian kustom",
+  "extensionsErrorLoading": "Error memuat ekstensi",
+
+  "extensionCustomTrackMatching": "Pencocokan Lagu Kustom",
+  "extensionPostProcessing": "Pasca-Pemrosesan",
+  "extensionHooksAvailable": "{count} hook tersedia",
+  "extensionPatternsCount": "{count} pola",
+  "extensionStrategy": "Strategi: {strategy}",
+
+  "aboutDoubleDouble": "DoubleDouble",
+  "aboutDoubleDoubleDesc": "API luar biasa untuk unduhan Amazon Music. Terima kasih sudah membuatnya gratis!",
+  "aboutDabMusic": "DAB Music",
+  "aboutDabMusicDesc": "API streaming Qobuz terbaik. Unduhan Hi-Res tidak akan mungkin tanpa ini!",
+
+  "queueTitle": "Antrian Unduhan",
+  "queueClearAll": "Hapus Semua",
+  "queueClearAllMessage": "Apakah Anda yakin ingin menghapus semua unduhan?",
+
+  "albumFolderArtistAlbum": "Artis / Album",
+  "albumFolderArtistAlbumSubtitle": "Albums/Nama Artis/Nama Album/",
+  "albumFolderArtistYearAlbum": "Artis / [Tahun] Album",
+  "albumFolderArtistYearAlbumSubtitle": "Albums/Nama Artis/[2005] Nama Album/",
+  "albumFolderAlbumOnly": "Album Saja",
+  "albumFolderAlbumOnlySubtitle": "Albums/Nama Album/",
+  "albumFolderYearAlbum": "[Tahun] Album",
+  "albumFolderYearAlbumSubtitle": "Albums/[2005] Nama Album/",
+
+  "downloadedAlbumDeleteSelected": "Hapus yang Dipilih",
+  "downloadedAlbumDeleteMessage": "Hapus {count} {count, plural, =1{lagu} other{lagu}} dari album ini?\n\nIni juga akan menghapus file dari penyimpanan.",
+
+  "utilityFunctions": "Fungsi Utilitas",
+
+  "aboutMobileDeveloper": "Pengembang versi mobile",
+  "aboutOriginalCreator": "Pembuat SpotiFLAC asli",
+  "aboutLogoArtist": "Seniman berbakat yang membuat logo aplikasi kita yang indah!",
+  "aboutBinimumDesc": "Pembuat QQDL & HiFi API. Tanpa API ini, unduhan Tidal tidak akan ada!",
+  "aboutSachinsenalDesc": "Pembuat proyek HiFi asli. Fondasi dari integrasi Tidal!",
+  "aboutMobileSource": "Kode sumber mobile",
+  "aboutPCSource": "Kode sumber PC",
+  "aboutReportIssue": "Laporkan masalah",
+  "aboutReportIssueSubtitle": "Laporkan masalah yang Anda temui",
+  "aboutFeatureRequest": "Permintaan fitur",
+  "aboutFeatureRequestSubtitle": "Sarankan fitur baru untuk aplikasi",
+  "aboutBuyMeCoffee": "Belikan saya kopi",
+  "aboutBuyMeCoffeeSubtitle": "Dukung pengembangan di Ko-fi",
+  "aboutVersion": "Versi",
+  "aboutAppDescription": "Unduh lagu Spotify dalam kualitas lossless dari Tidal, Qobuz, dan Amazon Music.",
+
+  "providerPriorityTitle": "Prioritas Provider",
+  "providerPriorityDescription": "Seret untuk mengatur ulang urutan provider unduhan. Aplikasi akan mencoba provider dari atas ke bawah saat mengunduh lagu.",
+  "providerPriorityInfo": "Jika lagu tidak tersedia di provider pertama, aplikasi akan otomatis mencoba yang berikutnya.",
+  "providerBuiltIn": "Bawaan",
+  "providerExtension": "Ekstensi",
+
+  "metadataProviderPriorityTitle": "Prioritas Metadata",
+  "metadataProviderPriorityDescription": "Seret untuk mengatur ulang urutan provider metadata. Aplikasi akan mencoba provider dari atas ke bawah saat mencari lagu dan mengambil metadata.",
+  "metadataProviderPriorityInfo": "Deezer tidak memiliki batas rate dan direkomendasikan sebagai utama. Spotify mungkin membatasi rate setelah banyak permintaan.",
+  "metadataNoRateLimits": "Tidak ada batas rate",
+  "metadataMayRateLimit": "Mungkin dibatasi rate",
+
+  "queueEmpty": "Tidak ada unduhan dalam antrian",
+  "queueEmptySubtitle": "Tambahkan lagu dari layar beranda",
+  "queueClearCompleted": "Hapus yang selesai",
+  "queueDownloadFailed": "Unduhan Gagal",
+  "queueTrackLabel": "Lagu:",
+  "queueArtistLabel": "Artis:",
+  "queueErrorLabel": "Error:",
+  "queueUnknownError": "Error tidak diketahui",
+
+  "downloadedAlbumTracksHeader": "Lagu",
+  "downloadedAlbumDownloadedCount": "{count} diunduh",
+  "downloadedAlbumSelectedCount": "{count} dipilih",
+  "downloadedAlbumAllSelected": "Semua lagu dipilih",
+  "downloadedAlbumTapToSelect": "Ketuk lagu untuk memilih",
+  "downloadedAlbumDeleteCount": "Hapus {count} {count, plural, =1{lagu} other{lagu}}",
+  "downloadedAlbumSelectToDelete": "Pilih lagu untuk dihapus",
+  "downloadedAlbumDiscHeader": "Disc {discNumber}",
+
+  "folderOrganizationDescription": "Atur file yang diunduh ke dalam folder",
+  "folderOrganizationNone": "Tidak ada",
+  "folderOrganizationNoneSubtitle": "Semua file di folder unduhan",
+  "folderOrganizationByArtist": "Berdasarkan Artis",
+  "folderOrganizationByArtistSubtitle": "Folder terpisah untuk setiap artis",
+  "folderOrganizationByAlbum": "Berdasarkan Album",
+  "folderOrganizationByAlbumSubtitle": "Folder terpisah untuk setiap album",
+  "folderOrganizationByArtistAlbum": "Berdasarkan Artis & Album",
+  "folderOrganizationByArtistAlbumSubtitle": "Folder bersarang untuk artis dan album",
+
+  "recentTypeArtist": "Artis",
+  "recentTypeAlbum": "Album",
+  "recentTypeSong": "Lagu",
+  "recentTypePlaylist": "Playlist",
+
+  "recentPlaylistInfo": "Playlist: {name}",
+  "errorGeneric": "Error: {message}"
+}

lib/l10n/l10n.dart

@@ -0,0 +1,11 @@
+import 'package:flutter/material.dart';
+import 'package:spotiflac_android/l10n/app_localizations.dart';
+
+export 'package:spotiflac_android/l10n/app_localizations.dart';
+
+/// Extension to easily access AppLocalizations from BuildContext
+extension AppLocalizationsX on BuildContext {
+  /// Get the AppLocalizations instance
+  /// Usage: context.l10n.navHome
+  AppLocalizations get l10n => AppLocalizations.of(this);
+}

lib/l10n/supported_locales.dart

@@ -0,0 +1,30 @@
+// GENERATED FILE - DO NOT EDIT
+// Generated by: dart run tool/check_translations.dart 70
+// Only languages with >= 70% translation completion are included.
+// Translation is measured by comparing VALUES (not just key existence).
+//
+// To regenerate, run: dart run tool/check_translations.dart 70
+
+import 'package:flutter/widgets.dart';
+
+/// Minimum translation completion threshold used to filter languages.
+const int translationThreshold = 70;
+
+/// List of locales that meet the translation threshold.
+/// Only these languages will be available in the app.
+const List<Locale> filteredSupportedLocales = <Locale>[
+  Locale('en'),
+  Locale('ru'),
+  Locale('es', 'ES'),
+  Locale('id'),
+  Locale('pt', 'PT'),
+];
+
+/// Set of locale codes for quick lookup.
+const Set<String> filteredLocaleCodes = <String>{
+  'en',
+  'ru',
+  'es_ES',
+  'id',
+  'pt_PT',
+};

lib/main.dart

@@ -1,18 +1,24 @@
+import 'dart:io';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:path_provider/path_provider.dart';
 import 'package:spotiflac_android/app.dart';
 import 'package:spotiflac_android/providers/download_queue_provider.dart';
+import 'package:spotiflac_android/providers/extension_provider.dart';
 import 'package:spotiflac_android/services/notification_service.dart';
 import 'package:spotiflac_android/services/share_intent_service.dart';
+import 'package:spotiflac_android/services/cover_cache_manager.dart';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
   
-  // Initialize notification service
+  await CoverCacheManager.initialize();
-  await NotificationService().initialize();
+  debugPrint('CoverCacheManager initialized: ${CoverCacheManager.isInitialized}');
   
-  // Initialize share intent service
+  await Future.wait([
-  await ShareIntentService().initialize();
+    NotificationService().initialize(),
+    ShareIntentService().initialize(),
+  ]);
   
   runApp(
     ProviderScope(
@@ -24,14 +30,39 @@ void main() async {
 }
 
 /// Widget to eagerly initialize providers that need to load data on startup
-class _EagerInitialization extends ConsumerWidget {
+class _EagerInitialization extends ConsumerStatefulWidget {
   const _EagerInitialization({required this.child});
   final Widget child;
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  ConsumerState<_EagerInitialization> createState() => _EagerInitializationState();
-    // Eagerly initialize download history provider to load from storage
+}
+
+class _EagerInitializationState extends ConsumerState<_EagerInitialization> {
+  @override
+  void initState() {
+    super.initState();
+    _initializeExtensions();
+  }
+
+  Future<void> _initializeExtensions() async {
+    try {
+      final appDir = await getApplicationDocumentsDirectory();
+      final extensionsDir = '${appDir.path}/extensions';
+      final dataDir = '${appDir.path}/extension_data';
+      
+      await Directory(extensionsDir).create(recursive: true);
+      await Directory(dataDir).create(recursive: true);
+      
+      await ref.read(extensionProvider.notifier).initialize(extensionsDir, dataDir);
+    } catch (e) {
+      debugPrint('Failed to initialize extensions: $e');
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
     ref.watch(downloadHistoryProvider);
-    return child;
+    return widget.child;
   }
 }

lib/models/download_item.dart

@@ -3,22 +3,21 @@ import 'package:spotiflac_android/models/track.dart';
 
 part 'download_item.g.dart';
 
-/// Download status enum
 enum DownloadStatus {
   queued,
   downloading,
-  finalizing, // Embedding metadata, cover, lyrics
+  finalizing,
   completed,
   failed,
   skipped,
 }
 
-/// Error type enum for better error handling
 enum DownloadErrorType {
   unknown,
-  notFound,    // Track not found on any service
+  notFound,
-  rateLimit,   // Rate limited by service
+  rateLimit,
-  network,     // Network/connection error
+  network,
+  permission,
 }
 
 @JsonSerializable()
@@ -28,7 +27,7 @@ class DownloadItem {
   final String service;
   final DownloadStatus status;
   final double progress;
-  final double speedMBps; // Download speed in MB/s
+  final double speedMBps;
   final String? filePath;
   final String? error;
   final DownloadErrorType? errorType;
@@ -77,7 +76,6 @@ class DownloadItem {
     );
   }
 
-  /// Get user-friendly error message based on error type
   String get errorMessage {
     if (error == null) return '';
     
@@ -88,6 +86,8 @@ class DownloadItem {
         return 'Rate limit reached, try again later';
       case DownloadErrorType.network:
         return 'Connection failed, check your internet';
+      case DownloadErrorType.permission:
+        return 'Cannot write to folder, check storage permission';
       default:
         return error ?? 'An error occurred';
     }

lib/models/download_item.g.dart

@@ -51,4 +51,5 @@ const _$DownloadErrorTypeEnumMap = {
   DownloadErrorType.notFound: 'notFound',
   DownloadErrorType.rateLimit: 'rateLimit',
   DownloadErrorType.network: 'network',
+  DownloadErrorType.permission: 'permission',
 };

lib/models/settings.dart

@@ -12,17 +12,27 @@ class AppSettings {
   final bool embedLyrics;
   final bool maxQualityCover;
   final bool isFirstLaunch;
-  final int concurrentDownloads; // 1 = sequential (default), max 3
+  final int concurrentDownloads;
-  final bool checkForUpdates; // Check for updates on app start
+  final bool checkForUpdates;
-  final String updateChannel; // stable, preview
+  final String updateChannel;
-  final bool hasSearchedBefore; // Hide helper text after first search
+  final bool hasSearchedBefore;
-  final String folderOrganization; // none, artist, album, artist_album
+  final String folderOrganization;
-  final String historyViewMode; // list, grid
+  final String historyViewMode;
-  final bool askQualityBeforeDownload; // Show quality picker before each download
+  final String historyFilterMode;
-  final String spotifyClientId; // Custom Spotify client ID (empty = use default)
+  final bool askQualityBeforeDownload;
-  final String spotifyClientSecret; // Custom Spotify client secret (empty = use default)
+  final String spotifyClientId;
-  final bool useCustomSpotifyCredentials; // Whether to use custom credentials (if set)
+  final String spotifyClientSecret;
-  final String metadataSource; // spotify, deezer - source for search and metadata
+  final bool useCustomSpotifyCredentials;
+  final String metadataSource;
+  final bool enableLogging;
+  final bool useExtensionProviders;
+  final String? searchProvider;
+  final bool separateSingles;
+  final String albumFolderStructure;
+  final bool showExtensionStore;
+  final String locale;
+  final bool enableMp3Option;
+  final String lyricsMode;
 
   const AppSettings({
     this.defaultService = 'tidal',
@@ -33,17 +43,27 @@ class AppSettings {
     this.embedLyrics = true,
     this.maxQualityCover = true,
     this.isFirstLaunch = true,
-    this.concurrentDownloads = 1, // Default: sequential (off)
+    this.concurrentDownloads = 1,
-    this.checkForUpdates = true, // Default: enabled
+    this.checkForUpdates = true,
-    this.updateChannel = 'stable', // Default: stable releases only
+    this.updateChannel = 'stable',
-    this.hasSearchedBefore = false, // Default: show helper text
+    this.hasSearchedBefore = false,
-    this.folderOrganization = 'none', // Default: no folder organization
+    this.folderOrganization = 'none',
-    this.historyViewMode = 'grid', // Default: grid view
+    this.historyViewMode = 'grid',
-    this.askQualityBeforeDownload = true, // Default: ask quality before download
+    this.historyFilterMode = 'all',
-    this.spotifyClientId = '', // Default: use built-in credentials
+    this.askQualityBeforeDownload = true,
-    this.spotifyClientSecret = '', // Default: use built-in credentials
+    this.spotifyClientId = '',
-    this.useCustomSpotifyCredentials = true, // Default: use custom if set
+    this.spotifyClientSecret = '',
-    this.metadataSource = 'deezer', // Default: Deezer (no rate limit)
+    this.useCustomSpotifyCredentials = true,
+    this.metadataSource = 'deezer',
+    this.enableLogging = false,
+    this.useExtensionProviders = true,
+    this.searchProvider,
+    this.separateSingles = false,
+    this.albumFolderStructure = 'artist_album',
+    this.showExtensionStore = true,
+    this.locale = 'system',
+    this.enableMp3Option = false,
+    this.lyricsMode = 'embed',
   });
 
   AppSettings copyWith({
@@ -61,11 +81,22 @@ class AppSettings {
     bool? hasSearchedBefore,
     String? folderOrganization,
     String? historyViewMode,
+    String? historyFilterMode,
     bool? askQualityBeforeDownload,
     String? spotifyClientId,
     String? spotifyClientSecret,
     bool? useCustomSpotifyCredentials,
     String? metadataSource,
+    bool? enableLogging,
+    bool? useExtensionProviders,
+    String? searchProvider,
+    bool clearSearchProvider = false,
+    bool? separateSingles,
+    String? albumFolderStructure,
+    bool? showExtensionStore,
+    String? locale,
+    bool? enableMp3Option,
+    String? lyricsMode,
   }) {
     return AppSettings(
       defaultService: defaultService ?? this.defaultService,
@@ -82,11 +113,21 @@ class AppSettings {
       hasSearchedBefore: hasSearchedBefore ?? this.hasSearchedBefore,
       folderOrganization: folderOrganization ?? this.folderOrganization,
       historyViewMode: historyViewMode ?? this.historyViewMode,
+      historyFilterMode: historyFilterMode ?? this.historyFilterMode,
       askQualityBeforeDownload: askQualityBeforeDownload ?? this.askQualityBeforeDownload,
       spotifyClientId: spotifyClientId ?? this.spotifyClientId,
       spotifyClientSecret: spotifyClientSecret ?? this.spotifyClientSecret,
       useCustomSpotifyCredentials: useCustomSpotifyCredentials ?? this.useCustomSpotifyCredentials,
       metadataSource: metadataSource ?? this.metadataSource,
+      enableLogging: enableLogging ?? this.enableLogging,
+      useExtensionProviders: useExtensionProviders ?? this.useExtensionProviders,
+      searchProvider: clearSearchProvider ? null : (searchProvider ?? this.searchProvider),
+      separateSingles: separateSingles ?? this.separateSingles,
+      albumFolderStructure: albumFolderStructure ?? this.albumFolderStructure,
+      showExtensionStore: showExtensionStore ?? this.showExtensionStore,
+      locale: locale ?? this.locale,
+      enableMp3Option: enableMp3Option ?? this.enableMp3Option,
+      lyricsMode: lyricsMode ?? this.lyricsMode,
     );
   }