deflock-app/UPLOAD_REFACTOR_SUMMARY.md

Upload System Refactor - v1.5.3

Overview

Refactored the upload queue processing and OSM submission logic to properly handle the three distinct phases of OSM node operations, fixing the core issue where step 2 failures (node operations) weren't handled correctly.

Problem Analysis

The previous implementation incorrectly treated OSM interaction as a 2-step process:

1. Open changeset + submit node (conflated)
2. Close changeset

But OSM actually requires 3 distinct steps:

1. Create changeset
2. Perform node operation (create/modify/delete)
3. Close changeset

Issues Fixed:

• Step 2 failure handling: Node operation failures now properly close orphaned changesets and retry appropriately
• State confusion: Users now see exactly which of the 3 stages is happening or failed
• Error tracking: Each stage has appropriate retry logic and error messages
• UI clarity: Displays "Creating changeset...", "Uploading...", "Closing changeset..." with progress info

Changes Made

1. Uploader Service (lib/services/uploader.dart)

• Simplified UploadResult: Replaced complex boolean flags with simple success/failure pattern
• Three explicit methods:
  • createChangeset(PendingUpload) → Returns changeset ID
  • performNodeOperation(PendingUpload, changesetId) → Returns node ID
  • closeChangeset(changesetId) → Returns success/failure
• Legacy compatibility: upload() method still exists for simulate mode
• Better error context: Each method provides specific error messages for its stage

2. Upload Queue State (lib/state/upload_queue_state.dart)

• Three processing methods:
  • _processCreateChangeset() - Stage 1
  • _processNodeOperation() - Stage 2
  • _processChangesetClose() - Stage 3
• Proper state transitions: Clear progression through pending → creatingChangeset → uploading → closingChangeset → complete
• Stage-specific retry logic:
  • Stage 1 failure: Simple retry (no cleanup)
  • Stage 2 failure: Close orphaned changeset, retry from stage 1
  • Stage 3 failure: Exponential backoff up to 59 minutes
• Simulate mode support: All three stages work in simulate mode

3. Upload Queue UI (lib/screens/upload_queue_screen.dart)

• Enhanced status display: Shows retry attempts and time remaining (only when changeset close has failed)
• Better error visibility: Tap error icon to see detailed failure messages
• Stage progression: Clear visual feedback for each of the 3 stages
• Cleaner progress display: Time countdown only shows when there have been changeset close issues

4. Cache Cleanup (lib/state/upload_queue_state.dart, lib/services/node_cache.dart)

• Fixed orphaned pending nodes: Removing or clearing queue items now properly cleans up temporary cache markers
• Operation-specific cleanup:
  • Creates: Remove temporary nodes with _pending_upload markers
  • Edits: Remove temp nodes + _pending_edit markers from originals
  • Deletes: Remove _pending_deletion markers from originals
  • Extracts: Remove temp extracted nodes (leave originals unchanged)
• Added NodeCache methods: removePendingDeletionMarker() for deletion cancellation cleanup

5. Documentation Updates

• DEVELOPER.md: Added detailed explanation of three-stage architecture
• Changelog: Updated v1.5.3 release notes to highlight the fix
• Code comments: Improved throughout for clarity

Architecture Benefits

Brutalist Code Principles Applied:

1. Explicit over implicit: Three methods instead of one complex method
2. Simple error handling: Success/failure instead of multiple boolean flags
3. Clear responsibilities: Each method does exactly one thing
4. Minimal state complexity: Straightforward state machine progression

User Experience Improvements:

• Transparent progress: Users see exactly what stage is happening
• Better error messages: Specific context about which stage failed
• Proper retry behavior: Stage 2 failures no longer leave orphaned changesets
• Time awareness: Countdown shows when OSM will auto-close changesets

Maintainability Gains:

• Easier debugging: Each stage can be tested independently
• Clear failure points: No confusion about which step failed
• Simpler testing: Individual stages are unit-testable
• Future extensibility: Easy to add new upload operations or modify stages

Refined Retry Logic (Post-Testing Updates)

After initial testing feedback, the retry logic was refined to properly handle the 59-minute changeset window:

Three-Phase Retry Strategy:

• Phase 1 (Create Changeset): Up to 3 attempts with 20s delays → Error state (user retry required)
• Phase 2 (Submit Node): Unlimited attempts within 59-minute window → Error if time expires
• Phase 3 (Close Changeset): Unlimited attempts within 59-minute window → Auto-complete if time expires (trust OSM auto-close)

Key Behavioral Changes:

• 59-minute timer starts when changeset creation succeeds (not when node operation completes)
• Node submission failures retry indefinitely within the 59-minute window
• Changeset close failures retry indefinitely but never error out (always eventually complete)
• UI countdown only shows when there have been failures in phases 2 or 3
• Proper error messages: "Failed to create changeset after 3 attempts" vs "Could not submit node within 59 minutes"

Testing Recommendations

When testing this refactor:

1. Normal uploads: Verify all three stages show proper progression
2. Network interruption:
   • Test failure at each stage individually
   • Verify orphaned changesets are properly closed
   • Check retry logic works appropriately
3. Error handling:
   • Tap error icons to see detailed messages
   • Verify different error types show stage-specific context
4. Simulate mode: Confirm all three stages work in simulate mode
5. Queue management: Verify queue continues processing when individual items fail
6. Changeset closing: Test that changeset close retries work with exponential backoff

Rollback Plan

If issues are discovered, the legacy upload() method can be restored by:

1. Reverting _processCreateChangeset() to call up.upload(item) directly
2. Removing _processNodeOperation() and _processChangesetClose() calls
3. This would restore the old 2-stage behavior while keeping the UI improvements

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The core fix addresses the main issue you identified: step 2 failures (node operations) are now properly tracked and handled with appropriate cleanup and retry logic.