Skip modules with unavailable dependencies instead of aborting the run

A module declaring a dependency its command does not provide made
_ordered_modules() give up on the whole run, so a single wrong declaration
in a module scoped to several commands turned a forensic analysis into
zero executed modules with one warning to explain it.

Drop only the modules that cannot run: the one with the unavailable
dependency, and anything depending on it. Each gets its own warning naming
the module missing a dependency and the dependency it is missing, and the
remaining modules run in the same stable topological order as before. A
cycle in the dependency graph is still a programming error and still stops
the run.

README.md

@@ -84,7 +84,7 @@ details.
 
 Users can also add top-level commands to `mvt-ios` and `mvt-android` from
 installed Python packages or local files and folders. See the
-[custom CLI command documentation](https://docs.mvt.re/en/latest/custom_commands/)
+[custom CLI command documentation](https://docs.mvt.re/en/latest/development/custom_commands/)
 for the plugin entry points and `--load-command` interface.
 
 

docs/development.md

@@ -1,131 +0,0 @@
-# Development
-
-The Mobile Verification Toolkit team welcomes contributions of new forensic modules or other contributions which help improve the software.
-
-## Local environment
-
-MVT uses `uv` for dependency management. To install the project and development dependencies from the locked environment, run:
-
-```bash
-make install
-```
-
-## Testing
-
-MVT uses `pytest` for unit and integration tests. Code style consistency is maintained with `ruff` and `mypy`. All can
-be run automatically with:
-
-```bash
-make check
-```
-
-Run these tests before making new commits or opening pull requests.
-
-## Module dependencies
-
-Modules can require other modules to run first by declaring their classes in
-`dependencies`. The command runner uses a stable topological ordering, so the
-existing module list order is preserved wherever dependency constraints allow.
-
-```python
-class DependentModule(MVTModule):
-    dependencies = (PrerequisiteModule,)
-
-    def run(self):
-        prerequisite_results = self.get_dependency_results(PrerequisiteModule)
-```
-
-Selecting a single module also runs its transitive dependencies. If a dependency
-is unavailable or the dependency graph contains a cycle, the command logs a
-warning and does not run any modules.
-
-## Custom modules
-
-Module-running `check-*` commands can load custom modules from Python files that
-are not installed as part of MVT. Load one file with:
-
-```bash
-mvt-ios check-backup --load-module ./example_module.py --output ./out ./backup
-```
-
-You can also load a folder. MVT loads non-hidden top-level `*.py` files in
-sorted order and skips `__init__.py`:
-
-```bash
-mvt-ios check-fs --load-module ./custom_modules ./filesystem-dump
-```
-
-Set `MVT_CUSTOM_MODULES` to load a folder for every module-running command. This
-folder is loaded before any `--load-module` path:
-
-```bash
-MVT_CUSTOM_MODULES=./custom_modules mvt-android check-bugreport ./bugreport.zip
-```
-
-Custom modules are normal `MVTModule` subclasses:
-
-```python
-from mvt.common.module import MVTModule
-
-
-class ExampleCustomModule(MVTModule):
-    supported_commands = (("ios", "check-backup"), ("ios", "check-fs"))
-    slug = "example_custom_module"
-
-    def run(self):
-        self.results = [{"message": "custom module ran"}]
-
-    def check_indicators(self):
-        pass
-
-    def serialize(self, result):
-        return None
-```
-
-Use `supported_commands` to declare the platform/command pairs a module
-supports. Empty `supported_commands` means the module will not run and MVT logs
-a warning. This explicit declaration is required for every command. Supported
-pairs are:
-
-```python
-("ios", "check-backup")
-("ios", "check-fs")
-("ios", "check-iocs")
-("ios", "check-sysdiagnose")
-("android", "check-backup")
-("android", "check-bugreport")
-("android", "check-androidqf")
-("android", "check-intrusion-logs")
-("android", "check-iocs")
-```
-
-Custom modules can depend on existing MVT module classes. Dependencies are
-resolved with the same ordering logic as built-in modules, and custom modules
-are appended after built-ins before ordering:
-
-```python
-from mvt.common.module import MVTModule
-from mvt.ios.modules.backup.manifest import Manifest
-
-
-class DependentCustomModule(MVTModule):
-    supported_commands = (("ios", "check-backup"),)
-    dependencies = (Manifest,)
-
-    def run(self):
-        manifest_results = self.get_dependency_results(Manifest)
-        self.results = [{"manifest_entries": len(manifest_results)}]
-```
-
-## Profiling
-
-Some MVT modules extract and process significant amounts of data during the analysis process or while checking results against known indicators. Care must be
-take to avoid inefficient code paths as we add new modules.
-
-MVT modules can be profiled with Python built-in `cProfile` by setting the `MVT_PROFILE` environment variable.
-
-```bash
-MVT_PROFILE=1 dev/mvt-ios check-backup test_backup
-```
-
-Open an issue or PR if you are encountering significant performance issues when analyzing a device with MVT.

docs/development/custom_commands.md

@@ -1,7 +1,7 @@
 # Custom CLI Commands
 
 MVT can load additional top-level commands into `mvt-ios` and `mvt-android`.
-Custom commands are different from [custom forensic modules](development.md#custom-modules):
+Custom commands are different from [custom forensic modules](index.md#custom-modules):
 commands add new CLI operations, while modules add analysis steps to existing
 `check-*` commands.
 
@@ -56,6 +56,10 @@ pipx inject mvt my-mvt-plugin
 When MVT is installed in an active virtual environment, install the plugin with
 `pip` in that environment.
 
+Command packages that need their own settings, such as an API key, should store
+them in a namespaced [plugin configuration file](plugin_configuration.md)
+rather than in MVT's own `config.yaml`.
+
 ## Load a Command File
 
 For local commands that are not packaged, create a Python file that exports one

docs/development/index.md

@@ -0,0 +1,229 @@
+# Development
+
+The Mobile Verification Toolkit team welcomes contributions of new forensic modules or other contributions which help improve the software.
+
+## Local environment
+
+MVT uses `uv` for dependency management. To install the project and development dependencies from the locked environment, run:
+
+```bash
+make install
+```
+
+## Testing
+
+MVT uses `pytest` for unit and integration tests. Code style consistency is maintained with `ruff` and `mypy`. All can
+be run automatically with:
+
+```bash
+make check
+```
+
+Run these tests before making new commits or opening pull requests.
+
+## Module dependencies
+
+Modules can require other modules to run first by declaring their classes in
+`dependencies`. The command runner uses a stable topological ordering, so the
+existing module list order is preserved wherever dependency constraints allow.
+
+```python
+class DependentModule(MVTModule):
+    dependencies = (PrerequisiteModule,)
+
+    def run(self):
+        prerequisite_results = self.get_dependency_results(PrerequisiteModule)
+```
+
+Selecting a single module also runs its transitive dependencies.
+
+A module can only depend on modules the command it runs in also has. When a
+declared dependency is not among them, the command logs a warning naming the
+module and the missing dependency, skips that module and everything depending
+on it, and runs the rest of the analysis. Selecting such a module with
+`--module` therefore leaves nothing to run, which the warning explains.
+
+A cycle in the dependency graph is a programming error rather than a
+configuration problem: the command logs a warning and runs no modules at all.
+
+## Custom modules
+
+Module-running `check-*` commands can load custom modules from Python files that
+are not installed as part of MVT. Load one file with:
+
+```bash
+mvt-ios check-backup --load-module ./example_module.py --output ./out ./backup
+```
+
+You can also load a folder. MVT loads non-hidden top-level `*.py` files in
+sorted order and skips `__init__.py`:
+
+```bash
+mvt-ios check-fs --load-module ./custom_modules ./filesystem-dump
+```
+
+Set `MVT_CUSTOM_MODULES` to load a folder for every module-running command. This
+folder is loaded before any `--load-module` path:
+
+```bash
+MVT_CUSTOM_MODULES=./custom_modules mvt-android check-bugreport ./bugreport.zip
+```
+
+Custom modules are normal `MVTModule` subclasses:
+
+```python
+from mvt.common.module import MVTModule
+
+
+class ExampleCustomModule(MVTModule):
+    supported_commands = (("ios", "check-backup"), ("ios", "check-fs"))
+    slug = "example_custom_module"
+
+    def run(self):
+        self.results = [{"message": "custom module ran"}]
+
+    def check_indicators(self):
+        pass
+
+    def serialize(self, result):
+        return None
+```
+
+Use `supported_commands` to declare the platform/command pairs a module
+supports. Empty `supported_commands` means the module will not run and MVT logs
+a warning. This explicit declaration is required for every command. Supported
+pairs are:
+
+```python
+("ios", "check-backup")
+("ios", "check-fs")
+("ios", "check-iocs")
+("ios", "check-sysdiagnose")
+("android", "check-backup")
+("android", "check-bugreport")
+("android", "check-androidqf")
+("android", "check-intrusion-logs")
+("android", "check-iocs")
+```
+
+Custom modules can depend on existing MVT module classes. Dependencies are
+resolved with the same ordering logic as built-in modules, and custom modules
+are appended after built-ins before ordering:
+
+```python
+from mvt.common.module import MVTModule
+from mvt.ios.modules.backup.manifest import Manifest
+
+
+class DependentCustomModule(MVTModule):
+    supported_commands = (("ios", "check-backup"),)
+    dependencies = (Manifest,)
+
+    def run(self):
+        manifest_results = self.get_dependency_results(Manifest)
+        self.results = [{"manifest_entries": len(manifest_results)}]
+```
+
+## Installed module packages
+
+Python packages can register modules so they load automatically in every
+module-running `check-*` command, without `--load-module` or
+`MVT_CUSTOM_MODULES`. Register an entry point in the `mvt.modules` group in
+the package's `pyproject.toml`:
+
+```toml
+[project.entry-points."mvt.modules"]
+mvt-plugin-amnesty-custom = "mvt_plugin_amnesty_custom:get_modules"
+```
+
+The entry point must resolve to an iterable of `MVTModule` subclasses, or to
+a callable returning one:
+
+```python
+from mvt.common.module import MVTModule
+
+
+class PackagedModule(MVTModule):
+    supported_commands = (("ios", "check-backup"),)
+
+    def run(self):
+        self.results = [{"message": "packaged module ran"}]
+
+
+def get_modules() -> list[type[MVTModule]]:
+    return [PackagedModule]
+```
+
+Installed modules follow the same rules as other custom modules: each module
+must declare `supported_commands`, and dependencies are resolved with the
+standard ordering logic. A broken entry point is skipped with a warning and
+does not prevent MVT from running. As with custom commands, installed module
+packages run as trusted code inside the MVT process, so install only packages
+from sources you trust.
+
+For a `pipx` installation of MVT, inject the package into MVT's environment:
+
+```bash
+pipx inject mvt mvt-plugin-amnesty-custom
+```
+
+Module packages that need their own settings, such as an API key, should store
+them in a namespaced [plugin configuration file](plugin_configuration.md)
+rather than in MVT's own `config.yaml`.
+
+### Naming module packages
+
+Name module packages `mvt-plugin-<name>` (import package `mvt_plugin_<name>`),
+and include the name of the publishing organization or author so packages from
+different groups do not collide: for example, Amnesty International's custom
+modules would be distributed as `mvt-plugin-amnesty-custom` with the import
+package `mvt_plugin_amnesty_custom`.
+
+The prefix makes module packages easy to find on PyPI and keeps their import
+names from clashing with unrelated Python packages. It is a convention, not a
+technical requirement: modules load through the `mvt.modules` entry point
+regardless of what the package is called, and existing packages with other
+names keep working. Note that the prefix is also not a mark of authenticity —
+anyone can publish a package with any available name, so vet a module package
+and its publisher before installing it, whatever it is called.
+
+### Module logging
+
+Modules log through `self.log`, and MVT names the logger for where the module
+came from. MVT's own modules log under their dotted path (for example
+`mvt.ios.modules.mixed.whatsapp`). Everything external is namespaced under
+`mvt.ext` to keep it visually distinct from built-in modules and isolated from
+MVT's internal logger tree:
+
+- Installed packages log under `mvt.ext.<package>`, with the `mvt_plugin_`
+  prefix stripped: modules in `mvt_plugin_amnesty_custom` log as
+  `mvt.ext.amnesty_custom.*`.
+- Files loaded with `--load-module` or `MVT_CUSTOM_MODULES` log as
+  `mvt.ext.<file name>`.
+
+## Auditing loaded modules
+
+Because installed module packages load automatically, MVT records where every
+module came from:
+
+- `--list-modules` groups the available modules by source: MVT itself
+  (with its version), each installed package (with its version and, when
+  installed directly from a repository, the commit), and each file loaded
+  with `--load-module` or `MVT_CUSTOM_MODULES` (with the SHA-256 hash of the
+  file).
+- When a command runs with an `--output` folder, the `command.log` file
+  records one line per module source with the source's version or hash and
+  the list of modules loaded from it.
+
+## Profiling
+
+Some MVT modules extract and process significant amounts of data during the analysis process or while checking results against known indicators. Care must be
+take to avoid inefficient code paths as we add new modules.
+
+MVT modules can be profiled with Python built-in `cProfile` by setting the `MVT_PROFILE` environment variable.
+
+```bash
+MVT_PROFILE=1 dev/mvt-ios check-backup test_backup
+```
+
+Open an issue or PR if you are encountering significant performance issues when analyzing a device with MVT.

docs/development/plugin_configuration.md

@@ -0,0 +1,149 @@
+# Plugin Configuration
+
+Plugin packages that add [custom CLI commands](custom_commands.md) or
+[modules](index.md#installed-module-packages) often need to store their
+own settings, such as an API key, a server URL or the timestamp of the last
+synchronization. MVT provides a namespaced settings base class so each plugin
+keeps its configuration in its own file, and a data folder for anything else a
+plugin needs to keep on disk.
+
+!!! warning
+
+    Do not write plugin settings to MVT's own `config.yaml`. MVT rewrites that
+    file with the settings it knows about every time it starts, so any other
+    section is deleted.
+
+## Where Settings Are Stored
+
+Each plugin gets one YAML file in a `plugins` folder next to MVT's own
+configuration:
+
+```
+~/.config/mvt/plugins/<plugin name>.yaml
+```
+
+The exact parent folder follows the platform convention used for MVT's
+`config.yaml` (for example `~/Library/Application Support/mvt` on macOS). Use
+`mvt.common.plugin_config.plugin_config_path()` instead of building the path by
+hand.
+
+Plugin names must be lowercase and may only contain letters, digits and dashes,
+matching the `mvt-plugin-<name>` package naming convention. MVT creates the
+`plugins` folder with `0700` permissions and writes the settings files with
+`0600` permissions, because they commonly hold credentials. Files are written
+through a temporary file and moved into place, so an interrupted save never
+leaves a partially written settings file behind.
+
+## Plugin Data Folder
+
+Everything else a plugin keeps on disk, such as a cache, a downloaded artifact
+or synchronization state, belongs in the folder returned by the `data_folder()`
+class method of the plugin's settings class, or by
+`mvt.common.plugin_config.plugin_data_folder()` called with the plugin name if
+the plugin has no settings class:
+
+```
+~/.local/share/mvt/plugin-data/<plugin name>/                # Linux
+~/Library/Application Support/mvt/plugin-data/<plugin name>/ # macOS
+```
+
+The folder sits beside MVT's own data, such as the downloaded indicators. It is
+created if it is missing, with `0700` permissions. Asking for it again returns
+the same path and leaves the contents alone, so a plugin can ask for it every
+time it needs the folder. `ExamplePluginSettings` below is the settings class
+defined in the next section:
+
+```python
+import os
+
+
+def cache_path() -> str:
+    folder = ExamplePluginSettings.data_folder()
+    return os.path.join(folder, "virustotal_lookups_cache.json")
+```
+
+A plugin which has no settings class calls
+`plugin_data_folder("example-plugin")` instead.
+
+Do not fall back on a path of your own such as `~/.cache/example-plugin`: it
+is a Linux-only convention, and MVT will not create it for you.
+
+## Defining Plugin Settings
+
+Subclass `MVTPluginSettings`, set `plugin_name` and declare typed fields with
+defaults:
+
+```python
+from typing import Optional
+
+from mvt.common.plugin_config import MVTPluginSettings
+
+
+class ExamplePluginSettings(MVTPluginSettings):
+    plugin_name = "example-plugin"
+
+    API_KEY: Optional[str] = None
+    MAX_RESULTS: int = 25
+    LAST_SYNC: Optional[str] = None
+```
+
+`load()` returns the current settings and `save()` writes them back:
+
+```python
+from datetime import datetime, timezone
+
+import click
+
+
+def sync():
+    settings = ExamplePluginSettings.load()
+    if not settings.API_KEY:
+        raise click.ClickException(
+            "No API key configured. Set MVT_PLUGIN_EXAMPLE_PLUGIN_API_KEY or "
+            "run 'example-plugin configure'."
+        )
+
+    settings.LAST_SYNC = datetime.now(timezone.utc).isoformat()
+    settings.save()
+```
+
+A missing settings file is not an error: the plugin then runs on the field
+defaults and on whatever the environment provides. `save()` only persists the
+values that differ from the defaults, and it never touches MVT's `config.yaml`.
+A settings file that cannot be parsed, or that does not hold a mapping of
+setting names to values, raises a `PluginConfigLoadError` naming the file.
+
+Every subclass that sets its own `plugin_name` gets its own file and its own
+environment namespace. A subclass that does not redefine `plugin_name` inherits
+it, and therefore shares the file and the environment variables of its parent
+class.
+
+## Environment Variables
+
+Every field can also be set with an environment variable. The prefix is
+`MVT_PLUGIN_`, followed by the plugin name upper-cased with dashes replaced by
+underscores, followed by the field name. For the example above:
+
+```bash
+export MVT_PLUGIN_EXAMPLE_PLUGIN_API_KEY=...
+export MVT_PLUGIN_EXAMPLE_PLUGIN_MAX_RESULTS=50
+```
+
+Settings resolve in this order, from highest to lowest priority:
+
+1. Arguments passed to the settings class directly, such as
+   `ExamplePluginSettings(API_KEY="...")`
+2. Environment variables
+3. The plugin's YAML file
+4. The field defaults declared on the settings class
+
+!!! tip
+
+    On shared or multi-user machines, prefer passing API keys through
+    environment variables rather than saving them to the plugin file. `save()`
+    skips every value that the environment currently supplies, so a credential
+    provided that way is not copied into the settings file when a plugin saves
+    an unrelated setting.
+
+Unknown keys in a plugin's YAML file are ignored, so a settings file written by
+a newer version of a plugin does not break an older one.

mkdocs.yml

@@ -50,6 +50,7 @@ nav:
         - Check Android Intrusion Logs: "android/intrusion_logs.md"
     - Indicators of Compromise: "iocs.md"
     - Development:
-        - Development Instructions: "development.md"
+        - Development Instructions: "development/index.md"
-        - Custom CLI Commands: "custom_commands.md"
+        - Custom CLI Commands: "development/custom_commands.md"
+        - Plugin Configuration: "development/plugin_configuration.md"
     - License: "license.md"

src/mvt/common/cmd_check_iocs.py

@@ -9,6 +9,7 @@ from typing import Optional
 
 from mvt.common.command import Command
 from mvt.common.module import MVTModule
+from mvt.common.module_loader import get_module_logger
 from mvt.common.utils import exec_or_profile
 
 log = logging.getLogger(__name__)
@@ -76,7 +77,7 @@ class CmdCheckIOCS(Command):
                 )
 
                 m = iocs_module.from_json(
-                    file_path, log=logging.getLogger(iocs_module.__module__)
+                    file_path, log=get_module_logger(iocs_module)
                 )
                 if not m:
                     log.warning("No result from this module, skipping it")

src/mvt/common/command.py

@@ -19,7 +19,12 @@ from .alerts import AlertLevel, AlertStore
 from .config import settings
 from .indicators import Indicators
 from .module import EncryptedBackupError, MVTModule, run_module, save_timeline
-from .module_loader import module_supports_command
+from .module_loader import (
+    ModuleOrigin,
+    get_module_logger,
+    get_module_origin,
+    module_supports_command,
+)
 from .module_types import ModuleTimeline, URLResult
 from .utils import (
     CustomJSONEncoder,
@@ -210,10 +215,34 @@ class Command:
         for file in generate_hashes_from_path(self.target_path, self.log):
             self.hash_values.append(file)
 
+    @staticmethod
+    def _modules_by_origin(
+        modules: list[type[MVTModule]],
+    ) -> dict[ModuleOrigin, list[str]]:
+        origins: dict[ModuleOrigin, list[str]] = {}
+        for module in modules:
+            origins.setdefault(get_module_origin(module), []).append(module.__name__)
+        return origins
+
     def list_modules(self) -> None:
         self.log.info("Following is the list of available %s modules:", self.name)
-        for module in self._available_modules():
+        for origin, module_names in self._modules_by_origin(
-            self.log.info(" - %s", module.__name__)
+            self._available_modules()
+        ).items():
+            self.log.info(
+                " - Modules from %s: %s", origin.label, ", ".join(module_names)
+            )
+
+    def _log_loaded_modules(self, modules: list[type[MVTModule]]) -> None:
+        """Record the loaded modules and their origins for auditability."""
+        for origin, module_names in self._modules_by_origin(modules).items():
+            self.log.info(
+                "Loaded %d %s modules from %s: %s",
+                len(module_names),
+                self.name,
+                origin.label,
+                ", ".join(module_names),
+            )
 
     def _available_modules(self) -> list[type[MVTModule]]:
         modules = list(self.modules)
@@ -288,6 +317,81 @@ class Command:
         console.print("")
         console.print(panel)
 
+    def _skipped_modules(
+        self,
+        required: list[type[MVTModule]],
+        module_indexes: dict[type[MVTModule], int],
+    ) -> dict[type[MVTModule], tuple[type[MVTModule], type[MVTModule]]]:
+        """Return the modules to drop because a dependency is unavailable.
+
+        A module declaring a dependency this command cannot provide is unable
+        to run, and so is every module depending on it. Dropping only those
+        keeps a single wrong declaration - in a module scoped to several
+        commands, for example - from silencing an entire analysis.
+
+        The returned mapping gives, for each skipped module, the module which
+        is missing a dependency and the dependency it is missing.
+        """
+        skipped: dict[type[MVTModule], tuple[type[MVTModule], type[MVTModule]]] = {}
+        # Skipping the one module a run was asked for leaves nothing to run,
+        # which the caller reports instead.
+        remainder = (
+            "" if self.module_name else " The rest of the analysis will still run."
+        )
+
+        # Skipping one module can skip the modules depending on it, which the
+        # pass over the module list may already have gone past, so repeat the
+        # pass until nothing changes.
+        changed = True
+        while changed:
+            changed = False
+            for module in required:
+                if module in skipped:
+                    continue
+
+                for dependency in module.dependencies:
+                    if dependency not in module_indexes:
+                        skipped[module] = (module, dependency)
+                        changed = True
+                        self.log.warning(
+                            "Module %s will be SKIPPED: it depends on module "
+                            "%s, which is not available in this command.%s",
+                            module.__name__,
+                            dependency.__name__,
+                            remainder,
+                        )
+                        break
+
+                    if dependency in skipped:
+                        root, missing = skipped[dependency]
+                        skipped[module] = (root, missing)
+                        changed = True
+                        if dependency is root:
+                            self.log.warning(
+                                "Module %s will be SKIPPED: it depends on "
+                                "module %s, itself skipped for depending on "
+                                "unavailable module %s.%s",
+                                module.__name__,
+                                dependency.__name__,
+                                missing.__name__,
+                                remainder,
+                            )
+                        else:
+                            self.log.warning(
+                                "Module %s will be SKIPPED: it depends on "
+                                "skipped module %s, in a chain starting at "
+                                "module %s, which depends on unavailable "
+                                "module %s.%s",
+                                module.__name__,
+                                dependency.__name__,
+                                root.__name__,
+                                missing.__name__,
+                                remainder,
+                            )
+                        break
+
+        return skipped
+
     def _ordered_modules(self) -> Optional[list[type[MVTModule]]]:
         """Return enabled modules in stable topological order."""
         modules = self._available_modules()
@@ -300,30 +404,34 @@ class Command:
         else:
             selected = [module for module in modules if module.enabled]
 
-        required = set(selected)
+        required: set[type[MVTModule]] = set()
         pending = list(selected)
         while pending:
             module = pending.pop()
+            if module in required:
+                continue
+            required.add(module)
             for dependency in module.dependencies:
-                if dependency not in module_indexes:
+                # Unavailable dependencies are reported by _skipped_modules().
-                    self.log.warning(
+                if dependency in module_indexes:
-                        "Module %s depends on unavailable module %s. "
-                        "No modules will be run.",
-                        module.__name__,
-                        dependency.__name__,
-                    )
-                    return None
-                if dependency not in required:
-                    required.add(dependency)
                     pending.append(dependency)
 
+        ordered_required = sorted(required, key=lambda module: module_indexes[module])
+        skipped = self._skipped_modules(ordered_required, module_indexes)
+        runnable = [module for module in ordered_required if module not in skipped]
+        if skipped and not runnable:
+            self.log.warning(
+                "Every selected module was skipped for an unavailable "
+                "dependency. No modules will be run."
+            )
+
         dependents: dict[type[MVTModule], list[type[MVTModule]]] = {
-            module: [] for module in required
+            module: [] for module in runnable
         }
-        indegree = {module: 0 for module in required}
+        indegree = {module: 0 for module in runnable}
-        for module in required:
+        for module in runnable:
             for dependency in module.dependencies:
-                if dependency not in required:
+                if dependency not in indegree:
                     continue
                 dependents[dependency].append(module)
                 indegree[module] += 1
@@ -342,7 +450,7 @@ class Command:
                 if indegree[dependent] == 0:
                     heappush(ready, (module_indexes[dependent], dependent))
 
-        if len(ordered) != len(required):
+        if len(ordered) != len(runnable):
             cyclic_modules = sorted(
                 (module.__name__ for module, count in indegree.items() if count > 0)
             )
@@ -360,6 +468,8 @@ class Command:
         if ordered_modules is None:
             return
 
+        self._log_loaded_modules(ordered_modules)
+
         try:
             self.init()
         except NotImplementedError:
@@ -368,7 +478,7 @@ class Command:
         executed_by_type: dict[type[MVTModule], MVTModule] = {}
         for module in ordered_modules:
 
-            module_logger = logging.getLogger(module.__module__)
+            module_logger = get_module_logger(module)
 
             m = module(
                 target_path=self.target_path,

src/mvt/common/help.py

@@ -8,7 +8,7 @@ HELP_MSG_VERSION = "Show the currently installed version of MVT"
 HELP_MSG_OUTPUT = "Specify a path to a folder where you want to store JSON results"
 HELP_MSG_IOC = "Path to indicators file (can be invoked multiple time)"
 HELP_MSG_FAST = "Avoid running time/resource consuming features"
-HELP_MSG_LIST_MODULES = "Print list of available modules and exit"
+HELP_MSG_LIST_MODULES = "Print list of available modules and their source, then exit"
 HELP_MSG_MODULE = "Name of a single module you would like to run instead of all"
 HELP_MSG_LOAD_MODULE = (
     "Load custom MVT module(s) from a Python file or folder "

src/mvt/common/module_loader.py

@@ -4,18 +4,28 @@
 #   https://license.mvt.re/1.1/
 
 import hashlib
+import importlib.metadata
 import importlib.util
 import inspect
+import json
 import logging
 import os
 import sys
+from dataclasses import dataclass
+from functools import lru_cache
 from pathlib import Path
 from types import ModuleType
 from typing import Iterable, Optional
 
 from .module import MVTModule
+from .version import MVT_VERSION
 
 MVT_CUSTOM_MODULES_ENV = "MVT_CUSTOM_MODULES"
+MODULES_ENTRY_POINT_GROUP = "mvt.modules"
+EXTERNAL_LOGGER_NAMESPACE = "mvt.ext"
+PLUGIN_PACKAGE_PREFIX = "mvt_plugin_"
+_ORIGIN_ATTRIBUTE = "_mvt_module_origin"
+_PATH_MODULE_PREFIX = "_mvt_custom_module_"
 log = logging.getLogger(__name__)
 
 
@@ -23,15 +33,74 @@ class CustomModuleLoadError(Exception):
     pass
 
 
+@dataclass(frozen=True)
+class ModuleOrigin:
+    """Describes where a loaded module came from, for auditability.
+
+    ``kind`` is one of ``builtin`` (shipped with MVT), ``package`` (loaded
+    from an installed package) or ``path`` (loaded from a file passed with
+    ``--load-module`` or the environment variable).
+    """
+
+    kind: str
+    name: str
+    version: Optional[str] = None
+    commit: Optional[str] = None
+    file_sha256: Optional[str] = None
+
+    @property
+    def label(self) -> str:
+        label = self.name
+        if self.version:
+            label += f"@{self.version}"
+        label = f"'{label}'"
+        if self.commit:
+            label += f" (commit {self.commit})"
+        if self.file_sha256:
+            label += f" (sha256: {self.file_sha256})"
+        return label
+
+
 def _module_name_for_path(path: Path) -> str:
     digest = hashlib.sha256(str(path).encode("utf-8")).hexdigest()[:16]
-    return f"_mvt_custom_module_{path.stem}_{digest}"
+    return f"{_PATH_MODULE_PREFIX}{path.stem}_{digest}"
+
+
+def get_module_logger(module_class: type[MVTModule]) -> logging.Logger:
+    """Return the logger a module's records should be emitted through.
+
+    Modules loaded from installed packages or file paths live outside the
+    "mvt" logger hierarchy, so their records would never reach the handlers
+    attached to the "mvt" logger and instead fall through to
+    logging.lastResort (which prints bare messages and drops anything below
+    WARNING). Their loggers are parented under the "mvt.ext" namespace,
+    keeping external module names from colliding with MVT's own logger
+    tree. File-path modules are named after their file instead of the
+    mangled internal import name, and packages following the recommended
+    "mvt_plugin_<name>" naming convention log under "mvt.ext.<name>".
+    """
+    name = module_class.__module__
+    if name == "mvt" or name.startswith("mvt."):
+        return logging.getLogger(name)
+
+    if name.startswith(_PATH_MODULE_PREFIX):
+        name = Path(get_module_origin(module_class).name).stem
+    else:
+        top_level, separator, rest = name.partition(".")
+        if top_level.startswith(PLUGIN_PACKAGE_PREFIX) and len(top_level) > len(
+            PLUGIN_PACKAGE_PREFIX
+        ):
+            name = top_level[len(PLUGIN_PACKAGE_PREFIX) :] + separator + rest
+
+    return logging.getLogger(f"{EXTERNAL_LOGGER_NAMESPACE}.{name}")
 
 
 def _iter_module_files(path: Path) -> Iterable[Path]:
     if path.is_file():
         if path.suffix != ".py":
-            raise CustomModuleLoadError(f"Custom module file is not a Python file: {path}")
+            raise CustomModuleLoadError(
+                f"Custom module file is not a Python file: {path}"
+            )
         yield path
         return
 
@@ -59,7 +128,9 @@ def _load_python_file(path: Path) -> ModuleType:
     try:
         spec.loader.exec_module(module)
     except Exception as exc:
-        raise CustomModuleLoadError(f"Unable to import custom module {path}: {exc}") from exc
+        raise CustomModuleLoadError(
+            f"Unable to import custom module {path}: {exc}"
+        ) from exc
 
     return module
 
@@ -84,17 +155,156 @@ def load_custom_modules_from_path(path: str) -> list[type[MVTModule]]:
     resolved_path = Path(path).expanduser().resolve()
 
     for module_file in _iter_module_files(resolved_path):
+        file_sha256 = hashlib.sha256(module_file.read_bytes()).hexdigest()
         loaded_module = _load_python_file(module_file)
+        origin = ModuleOrigin(
+            kind="path", name=str(module_file), file_sha256=file_sha256
+        )
         for module_class in discover_mvt_modules(loaded_module):
             key = (str(module_file), module_class.__qualname__)
             if key in seen:
                 continue
             seen.add(key)
+            setattr(module_class, _ORIGIN_ATTRIBUTE, origin)
             custom_modules.append(module_class)
 
     return custom_modules
 
 
+def _module_key(module_class: type[MVTModule]) -> tuple[str, str]:
+    try:
+        source = str(Path(inspect.getfile(module_class)).resolve())
+    except (OSError, TypeError):
+        source = module_class.__module__
+    return (source, module_class.__qualname__)
+
+
+def _distribution_commit(dist: importlib.metadata.Distribution) -> Optional[str]:
+    """Return the VCS commit a distribution was installed from, if recorded.
+
+    Packages installed directly from a repository (``pip install git+...``)
+    record the commit in ``direct_url.json`` (PEP 610).
+    """
+    try:
+        direct_url_text = dist.read_text("direct_url.json")
+        if not direct_url_text:
+            return None
+        commit = json.loads(direct_url_text).get("vcs_info", {}).get("commit_id")
+        return commit if isinstance(commit, str) else None
+    except Exception:
+        return None
+
+
+def _entry_point_origin(entry_point: importlib.metadata.EntryPoint) -> ModuleOrigin:
+    name = entry_point.name
+    version = None
+    commit = None
+    # Manually constructed entry points have no associated distribution.
+    dist = getattr(entry_point, "dist", None)
+    if dist is not None:
+        try:
+            name = dist.name or name
+            version = dist.version
+        except Exception:
+            pass
+        commit = _distribution_commit(dist)
+    return ModuleOrigin(kind="package", name=name, version=version, commit=commit)
+
+
+@lru_cache(maxsize=1)
+def _packages_distributions() -> dict[str, list[str]]:
+    try:
+        return dict(importlib.metadata.packages_distributions())
+    except Exception:
+        return {}
+
+
+def get_module_origin(module_class: type[MVTModule]) -> ModuleOrigin:
+    """Return the origin of a module class for auditing purposes."""
+    origin = module_class.__dict__.get(_ORIGIN_ATTRIBUTE)
+    if isinstance(origin, ModuleOrigin):
+        return origin
+
+    top_level = module_class.__module__.partition(".")[0]
+    if top_level == "mvt":
+        return ModuleOrigin(kind="builtin", name="mvt", version=MVT_VERSION)
+
+    distributions = _packages_distributions().get(top_level)
+    if distributions:
+        name = distributions[0]
+        version = None
+        commit = None
+        try:
+            dist = importlib.metadata.distribution(name)
+            version = dist.version
+            commit = _distribution_commit(dist)
+        except Exception:
+            pass
+        return ModuleOrigin(kind="package", name=name, version=version, commit=commit)
+
+    try:
+        source = str(Path(inspect.getfile(module_class)).resolve())
+    except (OSError, TypeError):
+        source = module_class.__module__
+    return ModuleOrigin(kind="path", name=source)
+
+
+def load_installed_modules() -> list[type[MVTModule]]:
+    """Load MVT modules registered by installed packages.
+
+    Packages register modules in the ``mvt.modules`` entry-point group. Each
+    entry point must resolve to an iterable of MVTModule subclasses, or to a
+    callable which returns one. A broken entry point is skipped with a
+    warning so that a faulty plugin package cannot break MVT.
+    """
+    try:
+        entry_points = importlib.metadata.entry_points(group=MODULES_ENTRY_POINT_GROUP)
+    except Exception as exc:
+        log.warning(
+            "Unable to discover installed module packages in entry-point group %s: %s",
+            MODULES_ENTRY_POINT_GROUP,
+            exc,
+        )
+        return []
+
+    installed_modules: list[type[MVTModule]] = []
+    ordered_entry_points = sorted(
+        entry_points, key=lambda entry_point: (entry_point.name, entry_point.value)
+    )
+    for entry_point in ordered_entry_points:
+        try:
+            loaded = entry_point.load()
+            if callable(loaded) and not isinstance(loaded, type):
+                loaded = loaded()
+            module_classes = list(loaded)
+        except (Exception, SystemExit) as exc:
+            log.warning(
+                "Unable to load modules from entry point %s (%s): %s",
+                entry_point.name,
+                entry_point.value,
+                exc,
+            )
+            continue
+
+        origin = _entry_point_origin(entry_point)
+        for module_class in module_classes:
+            if not (
+                isinstance(module_class, type) and issubclass(module_class, MVTModule)
+            ):
+                log.warning(
+                    "Entry point %s (%s) provided %r which is not an "
+                    "MVTModule subclass",
+                    entry_point.name,
+                    entry_point.value,
+                    module_class,
+                )
+                continue
+            setattr(module_class, _ORIGIN_ATTRIBUTE, origin)
+            installed_modules.append(module_class)
+
+    return installed_modules
+
+
 def load_custom_modules(paths: Optional[Iterable[str]] = None) -> list[type[MVTModule]]:
     search_paths: list[str] = []
     env_path = os.environ.get(MVT_CUSTOM_MODULES_ENV)
@@ -105,10 +315,17 @@ def load_custom_modules(paths: Optional[Iterable[str]] = None) -> list[type[MVTM
 
     custom_modules: list[type[MVTModule]] = []
     seen: set[tuple[str, str]] = set()
+
+    for module_class in load_installed_modules():
+        key = _module_key(module_class)
+        if key in seen:
+            continue
+        seen.add(key)
+        custom_modules.append(module_class)
+
     for path in search_paths:
         for module_class in load_custom_modules_from_path(path):
-            source = Path(inspect.getfile(module_class)).resolve()
+            key = _module_key(module_class)
-            key = (str(source), module_class.__qualname__)
             if key in seen:
                 continue
             seen.add(key)

src/mvt/common/plugin_config.py

@@ -0,0 +1,299 @@
+# Mobile Verification Toolkit (MVT)
+# Copyright (c) 2021-2026 The MVT Authors.
+# Use of this software is governed by the MVT License 1.1 that can be found at
+#   https://license.mvt.re/1.1/
+
+import contextlib
+import json
+import os
+import re
+import tempfile
+from typing import Any, ClassVar, Dict, List, Tuple, Type, TypeVar
+
+import yaml
+from appdirs import user_config_dir, user_data_dir
+from pydantic import ValidationError
+from pydantic_settings import (
+    BaseSettings,
+    EnvSettingsSource,
+    PydanticBaseSettingsSource,
+    SettingsConfigDict,
+    YamlConfigSettingsSource,
+)
+
+PLUGIN_CONFIG_FOLDER_NAME = "plugins"
+# Not "plugins": on macOS the configuration and data folders are the same
+# directory, and that name already holds the settings files.
+PLUGIN_DATA_FOLDER_NAME = "plugin-data"
+PLUGIN_ENV_PREFIX = "MVT_PLUGIN_"
+
+PLUGIN_NAME_PATTERN = re.compile(r"[a-z0-9][a-z0-9-]*")
+
+PluginSettingsType = TypeVar("PluginSettingsType", bound="MVTPluginSettings")
+
+
+class PluginConfigLoadError(Exception):
+    pass
+
+
+def validate_plugin_name(plugin_name: Any) -> str:
+    """
+    Check that a plugin name is safe to use in a file name and an env variable.
+
+    :param plugin_name: Name to validate.
+    :returns: The validated plugin name.
+    """
+    if not isinstance(plugin_name, str):
+        raise TypeError(
+            f"Plugin name must be a string, not {type(plugin_name).__name__}"
+        )
+    if not PLUGIN_NAME_PATTERN.fullmatch(plugin_name):
+        raise ValueError(
+            f"Invalid plugin name {plugin_name!r}: plugin names must start with a "
+            "lowercase letter or a digit and may only contain lowercase letters, "
+            "digits and dashes"
+        )
+    return plugin_name
+
+
+def plugin_config_folder() -> str:
+    """
+    Return the folder where plugins store their configuration files.
+
+    The path is resolved on every call so it always reflects the current
+    environment.
+    """
+    return os.path.join(user_config_dir("mvt"), PLUGIN_CONFIG_FOLDER_NAME)
+
+
+def plugin_config_path(plugin_name: str) -> str:
+    """
+    Return the path of the configuration file of a given plugin.
+
+    :param plugin_name: Name of the plugin.
+    """
+    return os.path.join(
+        plugin_config_folder(), f"{validate_plugin_name(plugin_name)}.yaml"
+    )
+
+
+def plugin_data_folder(plugin_name: str) -> str:
+    """
+    Return the folder where a given plugin stores its data, creating it.
+
+    Plugins should keep whatever they persist, such as caches or downloaded
+    artifacts, in this folder. It is created with owner-only permissions. The
+    path is resolved on every call so it always reflects the current
+    environment. A plugin with a settings class calls
+    `MVTPluginSettings.data_folder()` instead, which passes `plugin_name` here.
+
+    :param plugin_name: Name of the plugin.
+    :returns: The path of the data folder of the plugin.
+    """
+    # Validate the name before anything is created, so an unsafe name cannot
+    # leave a folder behind.
+    name = validate_plugin_name(plugin_name)
+
+    # makedirs() applies its mode only to the last folder of the path, so
+    # MVT's own data folder keeps the default permissions while the two
+    # plugin folders are private.
+    data_folder = os.path.join(user_data_dir("mvt"), PLUGIN_DATA_FOLDER_NAME)
+    os.makedirs(data_folder, mode=0o700, exist_ok=True)
+
+    folder = os.path.join(data_folder, name)
+    os.makedirs(folder, mode=0o700, exist_ok=True)
+    return folder
+
+
+def plugin_env_prefix(plugin_name: str) -> str:
+    """
+    Return the environment variable prefix used by a given plugin.
+
+    Dashes are replaced by underscores. Plugin names cannot contain underscores,
+    so two different plugin names never share an environment namespace.
+
+    :param plugin_name: Name of the plugin.
+    """
+    name = validate_plugin_name(plugin_name).upper().replace("-", "_")
+    return f"{PLUGIN_ENV_PREFIX}{name}_"
+
+
+def _settings_plugin_name(settings_cls: Type[BaseSettings]) -> str:
+    plugin_name = getattr(settings_cls, "plugin_name", None)
+    if plugin_name is None:
+        raise TypeError(
+            f"{settings_cls.__name__} must set a 'plugin_name' class attribute to "
+            "namespace its configuration file and environment variables"
+        )
+    return validate_plugin_name(plugin_name)
+
+
+def _plugin_yaml_source(
+    settings_cls: Type[BaseSettings], config_path: str
+) -> YamlConfigSettingsSource:
+    """
+    Build the YAML settings source of a plugin, reporting unusable files.
+
+    A missing file is not an error, but a file which cannot be parsed or which
+    does not hold a mapping of setting names is reported with its path.
+    """
+    try:
+        return YamlConfigSettingsSource(settings_cls, config_path)
+    except yaml.YAMLError as exc:
+        raise PluginConfigLoadError(
+            f"Invalid plugin configuration file {config_path}: {exc}"
+        ) from exc
+    except (TypeError, ValueError) as exc:
+        raise PluginConfigLoadError(
+            f"Invalid plugin configuration file {config_path}: the file must "
+            "contain a mapping of setting names to values"
+        ) from exc
+
+
+class MVTPluginSettings(BaseSettings):
+    """
+    Base class for plugin-namespaced settings.
+
+    Subclass with typed fields and set `plugin_name`. Values resolve from
+    constructor arguments, then environment variables (MVT_PLUGIN_<NAME>_*),
+    then the plugin's YAML file (~/.config/mvt/plugins/<name>.yaml), then field
+    defaults.
+
+    Plugins must not store their settings in MVT's own configuration file: MVT
+    rewrites it with the fields it knows about, dropping anything else.
+
+    `data_folder()` returns the folder the plugin keeps its data in.
+    """
+
+    model_config = SettingsConfigDict(extra="ignore")
+
+    plugin_name: ClassVar[str]
+
+    def __init_subclass__(cls, **kwargs: Any) -> None:
+        super().__init_subclass__(**kwargs)
+        plugin_name = _settings_plugin_name(cls)
+        # Namespace the environment variables of this plugin. Each pydantic
+        # model gets its own configuration dictionary, so this does not leak
+        # into other plugins.
+        cls.model_config["env_prefix"] = plugin_env_prefix(plugin_name)
+
+    @classmethod
+    def settings_customise_sources(
+        cls,
+        settings_cls: Type[BaseSettings],
+        init_settings: PydanticBaseSettingsSource,
+        env_settings: PydanticBaseSettingsSource,
+        dotenv_settings: PydanticBaseSettingsSource,
+        file_secret_settings: PydanticBaseSettingsSource,
+    ) -> Tuple[PydanticBaseSettingsSource, ...]:
+        config_path = plugin_config_path(_settings_plugin_name(settings_cls))
+        yaml_source = _plugin_yaml_source(settings_cls, config_path)
+        # Explicit arguments take precedence over environment variables, which
+        # in turn take precedence over the configuration file.
+        return (init_settings, env_settings, yaml_source)
+
+    @classmethod
+    def load(cls: Type[PluginSettingsType]) -> PluginSettingsType:
+        """
+        Load the settings of the plugin.
+
+        A missing configuration file is not an error: the settings then come
+        from the environment and from the field defaults.
+        """
+        return cls()
+
+    @classmethod
+    def data_folder(cls) -> str:
+        """
+        Return the data folder of the plugin, creating it.
+
+        The folder is the one plugin_data_folder() returns for `plugin_name`,
+        so a plugin with a settings class does not repeat its name.
+        """
+        return plugin_data_folder(_settings_plugin_name(cls))
+
+    def _environment_values(self) -> Dict[str, Any]:
+        """
+        Return the settings values currently supplied by the environment.
+
+        Values are validated by the model, so they can be compared with the
+        values held by this instance.
+        """
+        settings_cls = type(self)
+        raw_values = EnvSettingsSource(settings_cls)()
+        names = [name for name in raw_values if name in settings_cls.model_fields]
+        if not names:
+            return {}
+
+        # Fall back on the current values for the fields the environment does
+        # not set, so that required fields do not fail validation here.
+        current_values = json.loads(self.model_dump_json())
+        try:
+            from_environment = settings_cls.model_validate(
+                {**current_values, **raw_values}
+            )
+        except ValidationError:
+            # An environment variable which the model cannot validate must not
+            # stop the other environment values from being recognised, or a
+            # credential would be written to the configuration file.
+            return self._environment_values_by_field(current_values, raw_values, names)
+        return {name: getattr(from_environment, name) for name in names}
+
+    def _environment_values_by_field(
+        self,
+        current_values: Dict[str, Any],
+        raw_values: Dict[str, Any],
+        names: List[str],
+    ) -> Dict[str, Any]:
+        """
+        Validate each environment value on its own, skipping unusable ones.
+
+        :param current_values: Serialized values held by this instance.
+        :param raw_values: Values supplied by the environment.
+        :param names: Names of the fields set by the environment.
+        """
+        settings_cls = type(self)
+        values = {}
+        for name in names:
+            try:
+                from_environment = settings_cls.model_validate(
+                    {**current_values, name: raw_values[name]}
+                )
+            except ValidationError:
+                continue
+            values[name] = getattr(from_environment, name)
+        return values
+
+    def save(self) -> None:
+        """
+        Save the current settings to the configuration file of the plugin.
+
+        Only values which differ from the field defaults are persisted. Values
+        which come from the environment are not written to disk, so credentials
+        passed as environment variables stay out of the configuration file.
+        MVT's own configuration file is never modified.
+        """
+        config_folder = plugin_config_folder()
+        if not os.path.isdir(config_folder):
+            os.makedirs(config_folder, mode=0o700, exist_ok=True)
+
+        values = json.loads(self.model_dump_json(exclude_defaults=True))
+        for name, environment_value in self._environment_values().items():
+            if name in values and getattr(self, name, None) == environment_value:
+                del values[name]
+
+        # Settings files can hold credentials, so write them through a private
+        # temporary file and move it in place. The file is then never partially
+        # written and never briefly readable by other users.
+        config_path = plugin_config_path(self.plugin_name)
+        descriptor, temporary_path = tempfile.mkstemp(
+            dir=config_folder, prefix=f".{self.plugin_name}-", suffix=".yaml"
+        )
+        try:
+            with os.fdopen(descriptor, "w") as config_file:
+                config_file.write(yaml.dump(values, default_flow_style=False))
+            os.replace(temporary_path, config_path)
+        except BaseException:
+            with contextlib.suppress(OSError):
+                os.unlink(temporary_path)
+            raise

src/mvt/common/utils.py

@@ -239,6 +239,13 @@ def init_logging(verbose: bool = False):
     """
     log = logging.getLogger("mvt")
     log.setLevel(logging.DEBUG)
+
+    # Importing an MVT CLI module calls init_logging() at import time, and
+    # loaded module packages may import one indirectly. Keep this idempotent
+    # so console log lines are not duplicated by a second handler.
+    if any(isinstance(handler, MVTLogHandler) for handler in log.handlers):
+        return
+
     consoleHandler = MVTLogHandler()
     consoleHandler.setFormatter(logging.Formatter("%(message)s"))
     if verbose:

tests/common/test_command.py

@@ -157,7 +157,7 @@ class TestCommand:
         assert not hasattr(cmd, "initialized")
         assert "Circular module dependency detected" in caplog.text
 
-    def test_unavailable_dependency_warns_and_stops(self, caplog):
+    def test_unavailable_dependency_only_skips_the_dependent_module(self, caplog):
         class UnavailableModule(RecordingModule):
             pass
 
@@ -165,14 +165,97 @@ class TestCommand:
             dependencies = (UnavailableModule,)
 
         cmd = RecordingCommand()
-        cmd.modules = [DependentModule]
+        cmd.modules = [DependentModule, IndependentModule, FirstModule]
+
+        with caplog.at_level(logging.WARNING):
+            cmd.run()
+
+        assert RecordingModule.run_order == ["IndependentModule", "FirstModule"]
+        assert cmd.initialized
+        assert "Module DependentModule will be SKIPPED" in caplog.text
+        assert "depends on module UnavailableModule" in caplog.text
+
+    def test_modules_depending_on_a_skipped_module_are_skipped_too(self, caplog):
+        class UnavailableModule(RecordingModule):
+            pass
+
+        class SkippedModule(RecordingModule):
+            dependencies = (UnavailableModule,)
+
+        class DependsOnSkippedModule(RecordingModule):
+            dependencies = (SkippedModule,)
+
+        class DependsOnTheChain(RecordingModule):
+            dependencies = (DependsOnSkippedModule,)
+
+        cmd = RecordingCommand()
+        cmd.modules = [
+            DependsOnTheChain,
+            DependsOnSkippedModule,
+            SkippedModule,
+            IndependentModule,
+        ]
+
+        with caplog.at_level(logging.WARNING):
+            cmd.run()
+
+        assert RecordingModule.run_order == ["IndependentModule"]
+        skip_warnings = [
+            record.getMessage()
+            for record in caplog.records
+            if "will be SKIPPED" in record.getMessage()
+        ]
+        assert len(skip_warnings) == 3
+        assert [warning.split()[1] for warning in skip_warnings] == [
+            "SkippedModule",
+            "DependsOnSkippedModule",
+            "DependsOnTheChain",
+        ]
+        # Every warning names the root cause: the module missing a dependency
+        # and the dependency it is missing.
+        assert all("UnavailableModule" in warning for warning in skip_warnings)
+        assert all("module SkippedModule" in warning for warning in skip_warnings[1:])
+
+    def test_explicitly_selected_module_with_missing_dependency_runs_nothing(
+        self, caplog
+    ):
+        class UnavailableModule(RecordingModule):
+            pass
+
+        class DependentModule(RecordingModule):
+            dependencies = (UnavailableModule,)
+
+        cmd = RecordingCommand(module_name="DependentModule")
+        cmd.modules = [DependentModule, IndependentModule]
 
         with caplog.at_level(logging.WARNING):
             cmd.run()
 
         assert RecordingModule.run_order == []
-        assert not hasattr(cmd, "initialized")
+        assert "Module DependentModule will be SKIPPED" in caplog.text
-        assert "depends on unavailable module UnavailableModule" in caplog.text
+        assert "No modules will be run" in caplog.text
+        # Nothing else was selected, so the warning must not promise that the
+        # analysis continues right before saying that it does not.
+        assert "The rest of the analysis will still run" not in caplog.text
+
+    def test_unaffected_dependency_chains_keep_their_order(self, caplog):
+        class UnavailableModule(RecordingModule):
+            pass
+
+        class SkippedModule(RecordingModule):
+            dependencies = (UnavailableModule,)
+
+        cmd = RecordingCommand()
+        cmd.modules = [ThirdModule, SkippedModule, SecondModule, FirstModule]
+
+        with caplog.at_level(logging.WARNING):
+            cmd.run()
+
+        assert RecordingModule.run_order == [
+            "FirstModule",
+            "SecondModule",
+            "ThirdModule",
+        ]
 
     def test_custom_modules_are_filtered_before_ordering(self):
         cmd = RecordingCommand()

tests/common/test_module_loader.py

@@ -3,10 +3,12 @@ import pytest
 from mvt.common.module import MVTModule
 from mvt.common.module_loader import (
     CustomModuleLoadError,
+    get_module_logger,
     load_custom_modules,
     load_custom_modules_from_path,
     module_supports_command,
 )
+from mvt.ios.modules.mixed.whatsapp import Whatsapp
 
 
 MODULE_TEMPLATE = """
@@ -144,3 +146,44 @@ def test_module_supports_command_honors_supported_commands(tmp_path):
 
     assert module_supports_command(module, "ios", "check-backup")
     assert not module_supports_command(module, "ios", "check-fs")
+
+
+def test_get_module_logger_keeps_builtin_names():
+    assert get_module_logger(Whatsapp).name == "mvt.ios.modules.mixed.whatsapp"
+
+
+def test_get_module_logger_parents_package_modules_under_mvt_ext():
+    class PackageModule(MVTModule):
+        pass
+
+    PackageModule.__module__ = "some_plugin_package.ios.custom"
+
+    assert (
+        get_module_logger(PackageModule).name
+        == "mvt.ext.some_plugin_package.ios.custom"
+    )
+
+
+def test_get_module_logger_strips_the_plugin_package_prefix():
+    class PluginModule(MVTModule):
+        pass
+
+    PluginModule.__module__ = "mvt_plugin_amnesty_custom.ios.custom"
+
+    assert get_module_logger(PluginModule).name == "mvt.ext.amnesty_custom.ios.custom"
+
+
+def test_get_module_logger_only_strips_the_prefix_from_the_top_level():
+    class NestedModule(MVTModule):
+        pass
+
+    NestedModule.__module__ = "other_package.mvt_plugin_sub"
+
+    assert get_module_logger(NestedModule).name == "mvt.ext.other_package.mvt_plugin_sub"
+
+
+def test_get_module_logger_names_path_modules_after_their_file(tmp_path):
+    module_path = _write_module(tmp_path / "my_custom_module.py", "PathModule")
+    module = load_custom_modules_from_path(str(module_path))[0]
+
+    assert get_module_logger(module).name == "mvt.ext.my_custom_module"

tests/common/test_plugin_config.py

@@ -0,0 +1,391 @@
+# Mobile Verification Toolkit (MVT)
+# Copyright (c) 2021-2026 The MVT Authors.
+# Use of this software is governed by the MVT License 1.1 that can be found at
+#   https://license.mvt.re/1.1/
+
+import os
+import stat
+import sys
+from typing import Optional
+
+import pytest
+import yaml
+
+from mvt.common.plugin_config import (
+    MVTPluginSettings,
+    PluginConfigLoadError,
+    plugin_config_folder,
+    plugin_config_path,
+    plugin_data_folder,
+    plugin_env_prefix,
+)
+
+
+class ExamplePluginSettings(MVTPluginSettings):
+    plugin_name = "example-plugin"
+
+    API_KEY: Optional[str] = None
+    CACHE_FOLDER: str = "cache"
+    MAX_RESULTS: int = 25
+
+
+class OtherPluginSettings(MVTPluginSettings):
+    plugin_name = "other-plugin"
+
+    API_KEY: Optional[str] = None
+
+
+@pytest.fixture
+def config_folder(tmp_path, monkeypatch):
+    monkeypatch.setattr(
+        "mvt.common.plugin_config.user_config_dir",
+        lambda *args, **kwargs: str(tmp_path),
+    )
+    return tmp_path
+
+
+@pytest.fixture
+def data_folder(tmp_path, monkeypatch):
+    folder = tmp_path / "data"
+    monkeypatch.setattr(
+        "mvt.common.plugin_config.user_data_dir",
+        lambda *args, **kwargs: str(folder),
+    )
+    return folder
+
+
+def _write_plugin_file(plugin_name, values):
+    config_path = plugin_config_path(plugin_name)
+    os.makedirs(os.path.dirname(config_path), exist_ok=True)
+    content = values if isinstance(values, str) else yaml.dump(values)
+    with open(config_path, "w") as config_file:
+        config_file.write(content)
+    return config_path
+
+
+def test_plugin_paths_and_prefixes_are_namespaced(config_folder):
+    assert plugin_config_folder() == str(config_folder / "plugins")
+    assert plugin_config_path("example-plugin") == str(
+        config_folder / "plugins" / "example-plugin.yaml"
+    )
+    assert plugin_env_prefix("example-plugin") == "MVT_PLUGIN_EXAMPLE_PLUGIN_"
+    assert plugin_env_prefix("other-plugin") == "MVT_PLUGIN_OTHER_PLUGIN_"
+
+
+def test_defaults_are_used_without_file_or_environment(config_folder):
+    settings = ExamplePluginSettings.load()
+
+    assert settings.API_KEY is None
+    assert settings.CACHE_FOLDER == "cache"
+    assert settings.MAX_RESULTS == 25
+    assert not os.path.exists(plugin_config_path("example-plugin"))
+
+
+def test_values_are_loaded_from_the_plugin_file(config_folder):
+    _write_plugin_file("example-plugin", {"API_KEY": "from-file", "MAX_RESULTS": 5})
+
+    settings = ExamplePluginSettings.load()
+
+    assert settings.API_KEY == "from-file"
+    assert settings.MAX_RESULTS == 5
+    assert settings.CACHE_FOLDER == "cache"
+
+
+def test_environment_overrides_the_plugin_file(config_folder, monkeypatch):
+    _write_plugin_file("example-plugin", {"API_KEY": "from-file", "MAX_RESULTS": 5})
+    monkeypatch.setenv("MVT_PLUGIN_EXAMPLE_PLUGIN_API_KEY", "from-environment")
+
+    settings = ExamplePluginSettings.load()
+
+    assert settings.API_KEY == "from-environment"
+    assert settings.MAX_RESULTS == 5
+
+
+def test_arguments_override_the_environment_and_the_plugin_file(
+    config_folder, monkeypatch
+):
+    _write_plugin_file("example-plugin", {"API_KEY": "from-file", "MAX_RESULTS": 5})
+    monkeypatch.setenv("MVT_PLUGIN_EXAMPLE_PLUGIN_API_KEY", "from-environment")
+    monkeypatch.setenv("MVT_PLUGIN_EXAMPLE_PLUGIN_MAX_RESULTS", "10")
+
+    settings = ExamplePluginSettings(API_KEY="from-argument")
+
+    assert settings.API_KEY == "from-argument"
+    assert settings.MAX_RESULTS == 10
+
+
+def test_save_and_load_round_trip(config_folder):
+    settings = ExamplePluginSettings.load()
+    settings.API_KEY = "saved-key"
+    settings.MAX_RESULTS = 100
+
+    settings.save()
+
+    config_path = plugin_config_path("example-plugin")
+    assert os.path.isfile(config_path)
+    with open(config_path) as config_file:
+        assert yaml.safe_load(config_file) == {
+            "API_KEY": "saved-key",
+            "MAX_RESULTS": 100,
+        }
+
+    reloaded = ExamplePluginSettings.load()
+    assert reloaded.API_KEY == "saved-key"
+    assert reloaded.MAX_RESULTS == 100
+    assert reloaded.CACHE_FOLDER == "cache"
+
+
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="POSIX file permissions are not available"
+)
+def test_saved_file_is_only_readable_by_the_user(config_folder):
+    settings = ExamplePluginSettings.load()
+    settings.API_KEY = "saved-key"
+
+    settings.save()
+
+    config_path = plugin_config_path("example-plugin")
+    assert stat.S_IMODE(os.stat(config_path).st_mode) == 0o600
+    folder_mode = stat.S_IMODE(os.stat(plugin_config_folder()).st_mode)
+    assert folder_mode & 0o077 == 0
+
+
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="POSIX file permissions are not available"
+)
+def test_save_restricts_the_permissions_of_an_existing_file(config_folder):
+    config_path = _write_plugin_file("example-plugin", {"API_KEY": "from-file"})
+    os.chmod(config_path, 0o644)
+
+    settings = ExamplePluginSettings.load()
+    settings.MAX_RESULTS = 100
+    settings.save()
+
+    assert stat.S_IMODE(os.stat(config_path).st_mode) == 0o600
+    assert os.listdir(plugin_config_folder()) == ["example-plugin.yaml"]
+
+
+def test_save_only_persists_non_default_values(config_folder):
+    settings = ExamplePluginSettings.load()
+    settings.CACHE_FOLDER = "another-cache"
+
+    settings.save()
+
+    with open(plugin_config_path("example-plugin")) as config_file:
+        assert yaml.safe_load(config_file) == {"CACHE_FOLDER": "another-cache"}
+
+
+def test_save_does_not_persist_values_coming_from_the_environment(
+    config_folder, monkeypatch
+):
+    monkeypatch.setenv("MVT_PLUGIN_EXAMPLE_PLUGIN_API_KEY", "environment-secret")
+
+    settings = ExamplePluginSettings.load()
+    assert settings.API_KEY == "environment-secret"
+    settings.MAX_RESULTS = 100
+    settings.save()
+
+    with open(plugin_config_path("example-plugin")) as config_file:
+        assert yaml.safe_load(config_file) == {"MAX_RESULTS": 100}
+
+
+def test_an_invalid_environment_variable_still_protects_the_other_values(
+    config_folder, monkeypatch
+):
+    monkeypatch.setenv("MVT_PLUGIN_EXAMPLE_PLUGIN_API_KEY", "environment-secret")
+    monkeypatch.setenv("MVT_PLUGIN_EXAMPLE_PLUGIN_MAX_RESULTS", "not-an-int")
+
+    settings = ExamplePluginSettings(MAX_RESULTS=100)
+    assert settings.API_KEY == "environment-secret"
+    settings.save()
+
+    with open(plugin_config_path("example-plugin")) as config_file:
+        saved_values = yaml.safe_load(config_file)
+    assert saved_values == {"MAX_RESULTS": 100}
+    assert "API_KEY" not in saved_values
+
+
+def test_save_persists_values_which_differ_from_the_environment(
+    config_folder, monkeypatch
+):
+    monkeypatch.setenv("MVT_PLUGIN_EXAMPLE_PLUGIN_API_KEY", "environment-secret")
+
+    settings = ExamplePluginSettings.load()
+    settings.API_KEY = "chosen-key"
+    settings.save()
+
+    with open(plugin_config_path("example-plugin")) as config_file:
+        assert yaml.safe_load(config_file) == {"API_KEY": "chosen-key"}
+
+
+def test_save_does_not_write_the_mvt_configuration_file(config_folder):
+    settings = ExamplePluginSettings.load()
+    settings.API_KEY = "saved-key"
+
+    settings.save()
+
+    assert os.listdir(config_folder) == ["plugins"]
+
+
+def test_unknown_keys_in_the_plugin_file_are_ignored(config_folder):
+    _write_plugin_file(
+        "example-plugin",
+        {"API_KEY": "from-file", "UNKNOWN_SETTING": "ignored"},
+    )
+
+    settings = ExamplePluginSettings.load()
+
+    assert settings.API_KEY == "from-file"
+    assert not hasattr(settings, "UNKNOWN_SETTING")
+
+
+def test_unparsable_plugin_file_is_reported_with_its_path(config_folder):
+    config_path = _write_plugin_file("example-plugin", "API_KEY: [unclosed\n")
+
+    with pytest.raises(PluginConfigLoadError) as raised:
+        ExamplePluginSettings.load()
+
+    assert config_path in str(raised.value)
+
+
+def test_plugin_file_which_is_not_a_mapping_is_reported_with_its_path(config_folder):
+    config_path = _write_plugin_file("example-plugin", "- one\n- two\n")
+
+    with pytest.raises(PluginConfigLoadError) as raised:
+        ExamplePluginSettings.load()
+
+    assert config_path in str(raised.value)
+    assert "mapping of setting names" in str(raised.value)
+
+
+def test_plugins_do_not_interfere_with_each_other(config_folder, monkeypatch):
+    _write_plugin_file("other-plugin", {"API_KEY": "other-file-key"})
+    monkeypatch.setenv("MVT_PLUGIN_EXAMPLE_PLUGIN_API_KEY", "example-environment-key")
+
+    example_settings = ExamplePluginSettings.load()
+    other_settings = OtherPluginSettings.load()
+
+    assert example_settings.API_KEY == "example-environment-key"
+    assert other_settings.API_KEY == "other-file-key"
+
+    example_settings.MAX_RESULTS = 100
+    example_settings.save()
+    assert sorted(os.listdir(plugin_config_folder())) == [
+        "example-plugin.yaml",
+        "other-plugin.yaml",
+    ]
+    with open(plugin_config_path("other-plugin")) as config_file:
+        assert yaml.safe_load(config_file) == {"API_KEY": "other-file-key"}
+
+
+def test_subclass_without_plugin_name_is_rejected():
+    with pytest.raises(TypeError, match="plugin_name"):
+
+        class MissingNameSettings(MVTPluginSettings):
+            API_KEY: Optional[str] = None
+
+
+def test_subclass_with_invalid_plugin_name_is_rejected():
+    with pytest.raises(ValueError, match="Invalid plugin name"):
+
+        class InvalidNameSettings(MVTPluginSettings):
+            plugin_name = "Bad/Name"
+
+
+def test_underscores_are_not_allowed_in_plugin_names():
+    # Underscores are replaced by dashes in the environment prefix, so allowing
+    # both would let two plugin names share one environment namespace.
+    with pytest.raises(ValueError, match="Invalid plugin name"):
+
+        class UnderscoreNameSettings(MVTPluginSettings):
+            plugin_name = "under_score"
+
+    with pytest.raises(ValueError, match="Invalid plugin name"):
+        plugin_config_path("under_score")
+    with pytest.raises(ValueError, match="Invalid plugin name"):
+        plugin_env_prefix("under_score")
+
+
+@pytest.mark.parametrize(
+    "plugin_name", ["../escape", "folder/name", "UPPER", "-dash", ""]
+)
+def test_unsafe_plugin_names_have_no_configuration_path(plugin_name):
+    with pytest.raises(ValueError, match="Invalid plugin name"):
+        plugin_config_path(plugin_name)
+
+
+def test_data_folder_is_namespaced_and_created(data_folder):
+    folder = plugin_data_folder("example-plugin")
+
+    assert folder == str(data_folder / "plugin-data" / "example-plugin")
+    assert os.path.isdir(folder)
+
+
+def test_data_folder_can_be_requested_repeatedly(data_folder):
+    folder = plugin_data_folder("example-plugin")
+    with open(os.path.join(folder, "kept.json"), "w") as data_file:
+        data_file.write("{}")
+
+    assert plugin_data_folder("example-plugin") == folder
+    assert os.listdir(folder) == ["kept.json"]
+
+
+@pytest.mark.skipif(
+    sys.platform == "win32", reason="POSIX file permissions are not available"
+)
+def test_data_folder_is_only_accessible_by_the_user(data_folder):
+    folder = plugin_data_folder("example-plugin")
+
+    assert stat.S_IMODE(os.stat(folder).st_mode) & 0o077 == 0
+    parent_mode = stat.S_IMODE(os.stat(os.path.dirname(folder)).st_mode)
+    assert parent_mode & 0o077 == 0
+
+
+def test_plugins_get_their_own_data_folder(data_folder):
+    example_folder = plugin_data_folder("example-plugin")
+    other_folder = plugin_data_folder("other-plugin")
+
+    assert example_folder != other_folder
+    assert sorted(os.listdir(data_folder / "plugin-data")) == [
+        "example-plugin",
+        "other-plugin",
+    ]
+
+
+def test_data_folder_does_not_touch_the_configuration_folder(
+    config_folder, data_folder
+):
+    plugin_data_folder("example-plugin")
+
+    assert not os.path.exists(plugin_config_folder())
+
+
+@pytest.mark.parametrize(
+    "plugin_name", ["../escape", "folder/name", "UPPER", "-dash", ""]
+)
+def test_unsafe_plugin_names_have_no_data_folder(data_folder, plugin_name):
+    with pytest.raises(ValueError, match="Invalid plugin name"):
+        plugin_data_folder(plugin_name)
+
+    assert not os.path.exists(data_folder)
+
+
+def test_settings_class_knows_its_data_folder(data_folder):
+    folder = ExamplePluginSettings.data_folder()
+
+    assert folder == plugin_data_folder("example-plugin")
+    assert os.path.isdir(folder)
+    assert OtherPluginSettings.data_folder() != folder
+
+
+def test_settings_instance_uses_the_same_data_folder(config_folder, data_folder):
+    settings = ExamplePluginSettings.load()
+
+    assert settings.data_folder() == ExamplePluginSettings.data_folder()
+
+
+def test_subclass_without_its_own_name_shares_the_data_folder(data_folder):
+    class InheritingSettings(ExamplePluginSettings):
+        pass
+
+    assert InheritingSettings.data_folder() == ExamplePluginSettings.data_folder()

tests/common/test_utils.py

@@ -8,6 +8,7 @@ import logging
 import os
 from datetime import datetime
 
+from mvt.common.log import MVTLogHandler
 from mvt.common.utils import (
     CustomJSONEncoder,
     convert_datetime_to_iso,
@@ -16,6 +17,7 @@ from mvt.common.utils import (
     convert_unix_to_utc_datetime,
     generate_hashes_from_path,
     get_sha256_from_file_path,
+    init_logging,
 )
 
 from ..utils import get_artifact_folder
@@ -103,3 +105,20 @@ class TestCustomJSONEncoder:
             json.dumps({"name": "家".encode()}, cls=CustomJSONEncoder)
             == '{"name": "\\u5bb6"}'
         )
+
+
+class TestInitLogging:
+    def test__init_logging_is_idempotent(self):
+        # Loaded module packages may import an MVT CLI module, which calls
+        # init_logging() again at import time. A second call must not add
+        # a duplicate console handler.
+        log = logging.getLogger("mvt")
+        init_logging()
+        handler_count = sum(
+            isinstance(handler, MVTLogHandler) for handler in log.handlers
+        )
+        init_logging()
+        assert (
+            sum(isinstance(handler, MVTLogHandler) for handler in log.handlers)
+            == handler_count
+        )

tests/test_custom_modules.py

@@ -1,3 +1,7 @@
+import hashlib
+import importlib.metadata
+import json
+
 from click.testing import CliRunner
 
 from mvt.android.cli import check_bugreport
@@ -5,7 +9,9 @@ from mvt.android.cmd_check_androidqf import CmdAndroidCheckAndroidQF
 from mvt.android.cmd_check_backup import CmdAndroidCheckBackup
 from mvt.android.cmd_check_bugreport import CmdAndroidCheckBugreport
 from mvt.android.cmd_check_intrusion_logs import CmdAndroidCheckIntrusionLogs
+from mvt.common import module_loader
 from mvt.common.module import MVTModule
+from mvt.common.version import MVT_VERSION
 from mvt.ios.cli import check_backup, check_fs
 
 
@@ -106,6 +112,150 @@ def test_custom_modules_load_from_environment_without_cli_flag(tmp_path, monkeyp
     assert "EnvBugreportModule" in result.output
 
 
+class InstalledPackageModule(MVTModule):
+    supported_commands = (("ios", "check-backup"),)
+
+
+def get_installed_package_modules():
+    return [InstalledPackageModule]
+
+
+def _fake_entry_points(monkeypatch, value, name="test-modules"):
+    entry_point = importlib.metadata.EntryPoint(
+        name=name, value=value, group=module_loader.MODULES_ENTRY_POINT_GROUP
+    )
+
+    def fake_entry_points(*, group):
+        assert group == module_loader.MODULES_ENTRY_POINT_GROUP
+        return [entry_point]
+
+    monkeypatch.setattr(
+        module_loader.importlib.metadata, "entry_points", fake_entry_points
+    )
+
+
+def test_installed_module_package_loads_from_entry_point(monkeypatch):
+    _fake_entry_points(monkeypatch, f"{__name__}:get_installed_package_modules")
+
+    modules = module_loader.load_custom_modules()
+
+    assert modules == [InstalledPackageModule]
+
+
+def test_broken_module_entry_point_is_skipped(monkeypatch, caplog):
+    _fake_entry_points(monkeypatch, "nonexistent_module_xyz:get_modules")
+
+    with caplog.at_level("WARNING"):
+        modules = module_loader.load_custom_modules()
+
+    assert modules == []
+    assert "Unable to load modules from entry point" in caplog.text
+
+
+def test_entry_point_module_deduplicated_against_paths(monkeypatch, tmp_path):
+    _fake_entry_points(monkeypatch, f"{__name__}:get_installed_package_modules")
+    module_path = _write_custom_module(
+        tmp_path / "custom.py",
+        "PathLoadedModule",
+        (("ios", "check-backup"),),
+    )
+
+    modules = module_loader.load_custom_modules([str(module_path)])
+
+    assert [module.__name__ for module in modules] == [
+        "InstalledPackageModule",
+        "PathLoadedModule",
+    ]
+
+
+def test_list_modules_shows_module_sources(tmp_path, caplog):
+    module_path = _write_custom_module(
+        tmp_path / "custom.py",
+        "SourcedBackupModule",
+        (("ios", "check-backup"),),
+    )
+    file_sha256 = hashlib.sha256(module_path.read_bytes()).hexdigest()
+    custom_modules = module_loader.load_custom_modules([str(module_path)])
+
+    from mvt.ios.cmd_check_backup import CmdIOSCheckBackup
+
+    cmd = CmdIOSCheckBackup(target_path=str(tmp_path), custom_modules=custom_modules)
+    cmd.list_modules()
+
+    assert f" - Modules from 'mvt@{MVT_VERSION}':" in caplog.text
+    assert (
+        f" - Modules from '{module_path}' (sha256: {file_sha256}): SourcedBackupModule"
+        in caplog.text
+    )
+
+
+def test_builtin_module_origin():
+    from mvt.ios.modules.backup import BACKUP_MODULES
+
+    origin = module_loader.get_module_origin(BACKUP_MODULES[0])
+
+    assert origin.kind == "builtin"
+    assert origin.name == "mvt"
+    assert origin.version == MVT_VERSION
+
+
+def test_installed_module_origin(monkeypatch):
+    _fake_entry_points(monkeypatch, f"{__name__}:get_installed_package_modules")
+
+    modules = module_loader.load_custom_modules()
+
+    origin = module_loader.get_module_origin(modules[0])
+    assert origin.kind == "package"
+    assert origin.name == "test-modules"
+
+
+def test_distribution_commit_read_from_direct_url():
+    class FakeDistribution:
+        def read_text(self, filename):
+            assert filename == "direct_url.json"
+            return json.dumps(
+                {
+                    "url": "https://github.com/example/example-modules",
+                    "vcs_info": {"commit_id": "abc1234", "vcs": "git"},
+                }
+            )
+
+    assert module_loader._distribution_commit(FakeDistribution()) == "abc1234"
+
+
+def test_command_log_records_loaded_modules(tmp_path):
+    (tmp_path / "Manifest.db").touch()
+    (tmp_path / "Info.plist").touch()
+    module_path = _write_custom_module(
+        tmp_path / "custom.py",
+        "AuditedRunModule",
+        (("ios", "check-backup"),),
+        slug="audited_run_module",
+    )
+    file_sha256 = hashlib.sha256(module_path.read_bytes()).hexdigest()
+    output_path = tmp_path / "out"
+
+    result = CliRunner().invoke(
+        check_backup,
+        [
+            "--module",
+            "AuditedRunModule",
+            "--load-module",
+            str(module_path),
+            "--output",
+            str(output_path),
+            str(tmp_path),
+        ],
+    )
+
+    assert result.exit_code == 0
+    command_log = (output_path / "command.log").read_text(encoding="utf-8")
+    assert (
+        f"Loaded 1 check-backup modules from '{module_path}' "
+        f"(sha256: {file_sha256}): AuditedRunModule" in command_log
+    )
+
+
 class NestedBugreportModule(MVTModule):
     supported_commands = (("android", "check-bugreport"),)