CRITICAL FIX: Background tasks (especially blocklist_import) crashed mid-execution,
leaving partial state. On retry, the same bans were applied again, causing duplicates.
Solution: Content-hash based operation tracking for blocklist imports:
- Added import_runs table (migration 6) to track operations by source + content hash
- Before banning, check if this exact content has already been imported
- If completed: skip banning (already done), optionally re-warm cache
- If new or failed: proceed with ban and mark as completed or failed
Changes:
- Database: Migration 6 adds import_runs table with operation state tracking
- Model: Added ImportRunEntry for import run records
- Repository: New import_run_repo module with CRUD operations
- Workflow: Updated blocklist_import_workflow to check operation history before banning
- Dependencies: Registered import_run_repo for dependency injection
- Tests: Added test_import_source_idempotent_on_retry and test_import_source_different_content_not_reused
- Documentation: Added Task Idempotency section to Backend-Development.md
Verification:
- All 7 import tests pass (5 existing + 2 new idempotency tests)
- Type checking: mypy --strict ✅
- Linting: ruff ✅
- No API changes, backwards compatible via automatic migration
Fixes: Background tasks not idempotent #CRITICAL
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Replace fire-and-forget reschedule pattern with proper async/await:
- Changed reschedule() from fire-and-forget to awaitable async function
- Errors are now properly propagated instead of silently failing
- Added structured logging for reschedule start and completion
- Schedule updates are now deterministic and observable to callers
Changes:
- app/tasks/blocklist_import.py: Convert reschedule to async, remove asyncio.ensure_future
- tests/test_tasks/test_blocklist_import.py: Add tests for error propagation and logging
- Docs/Features.md: Document scheduling reliability guarantees
All 15 blocklist_import tests pass with 100% coverage.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
