Phase 2 T44 review noted that scene close still runs when a primary
turn is cancelled mid-stream and asked the implementer to review.
Review finding: the existing behavior is correct, not a bug. The
close-detection branch in post_turn consumes ONLY the user's prose
(fully appended to the event_log BEFORE streaming starts) and the
current container name. It does NOT consume the bot's output. A user
who types "we're done here, fade out" and then hits Stop mid-stream
still meant to close — the cancelled bot beat doesn't invalidate
that intent.
- Document the rationale with an inline comment near the
close-detection branch in chat/web/turns.py.
- Add regression test
test_cancelled_turn_still_closes_scene_when_user_prose_signals_close
that drives a stream raising CancelledError on first iteration and
asserts the scene_closed event still lands.
Joseph Doherty
bfb2ffb6f6