[QA] ✅ VERIFICATION PASSED - All 288 backend tests pass including 7 new progress tracking tests. Implementation correctly adds database fields (progress_stage, progress_message, progress_percentage), CRUD operations, and API endpoint. Progress stages follow specification exactly: queued(10%) → searching(30%) → analyzing(60%) → synthesizing(80%) → completed(100%). Database persistence works with in-memory fallback for performance. Full QA report available at /tmp/qa-PPLX-62.md. Ready for deployment.

## Implementation Complete ### Changes Made **Models (backend/models.py:295-300):** - Added progress_stage field (default: 'queued') - Added progress_message field (default: 'Query queued for processing') - Added progress_percentage field (default: 10) - Added check constraint for valid progress stages **Database Migration (f3a4b5c6d7e8):** - Created migration to add the three progress tracking columns - Includes proper defaults for existing records **CRUD Operations (backend/crud.py:704-734):** - Added update_async_query_progress() function to update all progress fields atomically **Async Queries Router (backend/routers/async_queries.py):** - Updated stage percentages per spec: queued=10%, searching=30%, analyzing=60%, synthesizing=80%, complete=100% - Updated update_async_query_progress(), complete_async_query(), and fail_async_query() to persist to database - Updated process_async_query() background task to pass db_session_factory to progress helpers - Updated GET progress endpoint to read from database with in-memory fallback for real-time updates **Tests (backend/tests/test_async_queries.py):** - Added 7 new tests for database progress tracking - All 288 backend tests pass ### How to Verify 1. Create an async research query via POST /api/queries/async 2. Poll GET /api/queries/async/{request_id}/progress 3. Verify percentage updates through stages: 10% -> 30% -> 60% -> 80% -> 100% 4. Check database for persisted progress values