Opus stage-360 review caught that the docstring at api/streaming.py:40-43
said 'around the entire agent run' which is no longer accurate after the
narrow-lock refactor. The lock is now held only briefly for the env-mutation
critical section; the agent runs outside the lock and the finally block
re-acquires to atomically restore env vars.
Docstring now points to both narrow-lock implementations as references:
- _run_agent_streaming at line ~2719 (the original pattern)
- profile_env_for_background_worker at api/profiles.py:715 (added stage-360)
#2299 added test_env_lock_importable_from_streaming asserting reentrance,
which contradicts the architectural invariant enforced by QA
test_env_lock_is_non_reentrant. The QA test wins because the non-reentrant
property is what makes _ENV_LOCK catch deadlock bugs early.
Updated the new test to assert NON-reentrance to match the actual lock
type (threading.Lock) and the QA invariant.
#2299 introduced profile_env_for_background_worker() in api/profiles.py and
changed _ENV_LOCK from threading.Lock() to threading.RLock(). Both changes
were incorrect:
1. RLock masked rather than fixed the underlying deadlock. The QA
test_env_lock_is_non_reentrant test exists precisely to enforce
non-reentrance — RLock would let a single thread hold _ENV_LOCK across
nested critical sections, which hides bugs while still allowing
different-thread races.
2. The original context manager held _ENV_LOCK for the ENTIRE 'yield'
duration, meaning the lock was held for the full background worker's
runtime (title generation, compression, update summary — possibly
many seconds). That blocked ALL other sessions on _ENV_LOCK, which
the QA test_third_message_completes runtime test caught as a timeout
on the third sequential message.
Fix: mirror the narrow-lock pattern from _run_agent_streaming:
- Acquire _ENV_LOCK only for env mutation (set runtime_env + patch
skill modules)
- Release immediately, yield to worker (no lock held)
- Reacquire in finally to restore env + skill modules
Restored _ENV_LOCK back to threading.Lock(). All 20 QA tests now pass,
including test_third_message_completes (was timing out, now 35s).
- Remove duplicate mobile-close-btn from HTML
- Remove dead .mobile-close-btn CSS rules; unhide .close-preview at all viewports
- Change btnClearPreview tooltip from 'Hide workspace panel' to 'Close'
- Update tests across test_sprint41.py, test_sprint44.py, test_issue781.py,
and test_mobile_layout.py to match new single-button model
Hermes Agent