- Changed 'async for' to 'async with' for get_db_session()
- get_db_session() is @asynccontextmanager, requires async with not async for
- Created 5 comprehensive unit tests verifying the fix
- All tests pass, background loading now works correctly
- Created test_dependency_exception_handling.py with 5 comprehensive tests
- Tests verify proper handling of HTTPException in async generator dependencies
- All tests pass, confirming fix for 'generator didn't stop after athrow()' error
- Updated instructions with complete task documentation
