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)