Pre-release Opus review caught three correctness bugs in the original
PR #1350 SSE wiring beyond the snapshot/subscribe race:
A) **Notify-ordering race (MUST-FIX A):** _approval_sse_notify took _lock
only for the subscriber-list snapshot, then released it before
put_nowait. With two parallel submit_pending calls, T2's notify
could fire before T1's, leaving the UI showing pending_count=1 while
the server actually had 2 queued.
C) **Trailing approval lost (MUST-FIX C):** _handle_approval_respond
never called _approval_sse_notify after popping. With parallel
tool-call approvals (#527), a second approval queued behind the one
being responded to was invisible until the next event ever fired —
in practice, the agent thread parked on it would appear hung.
D) **Payload showed tail not head (MUST-FIX D):** payload built from
the just-appended entry instead of queue[0]. /api/approval/pending
returns the head; SSE returned the tail. Diverging contracts.
Fix:
- Split into _approval_sse_notify_locked (caller holds _lock, no
internal locking) and _approval_sse_notify (convenience wrapper).
- submit_pending: call _locked variant inside the queue-mutation lock,
passing queue_list[0] as head.
- _handle_approval_respond: call _locked variant inside the pop lock,
passing the new head (or None/0 if queue is empty).
- Restore fallback poll to 1500ms (was bumped to 3000ms; degraded-mode
parity with v0.50.247 is more important than save 1.5s of polling).
New regression tests in tests/test_pr1350_sse_notify_correctness.py:
- test_second_submit_pending_sends_head_not_tail (D)
- test_respond_to_first_pushes_second_as_new_head (C)
- test_respond_to_only_pending_pushes_empty_state (C edge)
- test_pending_count_is_monotonic_under_contention (A)
Updated test_approval_sse.py to pin the new contract:
- _approval_sse_notify_locked(session_key, head, total)
- 1500ms fallback interval
Total: 3411 tests passing.
Co-authored-by: jasonjcwu <jasonjcwu@users.noreply.github.com>
Replaces the 1.5s HTTP polling loop with a Server-Sent Events endpoint
at /api/approval/stream that pushes approval events to the browser
instantly. The backend uses a thread-safe subscriber registry
(_approval_sse_subscribers) with bounded queues to prevent memory
leaks from slow clients. Frontend uses EventSource with automatic
fallback to 3s HTTP polling on SSE error.
- Backend: subscribe/unsubscribe/notify lifecycle in api/routes.py
- New route: GET /api/approval/stream?session_id=
- submit_pending() now calls _approval_sse_notify() after queue append
- Frontend: EventSource with onerror -> _startApprovalFallbackPoll()
- 30s keepalive comments, _CLIENT_DISCONNECT_ERRORS handling
- 42 new tests (static analysis + unit + concurrency)
Co-authored-by: jasonjcwu <jasonjcwu@users.noreply.github.com>
Rod Boev