CRITICAL: #1951 PENDING_GOAL_CONTINUATION race
Removes `PENDING_GOAL_CONTINUATION.discard(session_id)` from the
streaming worker's `finally` cleanup block. The marker is set inside
the SAME function call (line ~3328 on `goal_continue`) and the discard
in the `finally` (line ~3553) almost always raced ahead of the
frontend's SSE-receive → POST /api/chat/start round-trip, erasing
the marker before the consumer in routes.py could read it. The
consumer (`_start_chat_stream_for_session` in routes.py:6522) already
discards atomically when consuming, so removing the streaming-side
discard preserves single-use semantics and unblocks the
goal-continuation chain.
Adds tests/test_stage326_pending_goal_continuation_race.py with 5
regression guards:
1. streaming.py's finally must NOT discard PENDING_GOAL_CONTINUATION
2. routes.py consumer must check + set + discard atomically
3. PENDING_GOAL_CONTINUATION must be a set (GIL-safe single-op)
4. STREAM_GOAL_RELATED.pop must be keyed by stream_id, not session_id
5. PENDING_GOAL_CONTINUATION.add must precede the goal_continue SSE
emission in source ordering
HARDENING: #1956 composer-draft input validation
Per Opus, the POST /api/session/draft handler accepted unbounded /
arbitrary-typed text and files inputs. With the 400ms debounced
auto-save firing on every keystroke, a misbehaving client could
persist multi-MB strings into the session JSON. Adds:
- text: coerced to str if not already; clamped to 50_000 chars
- files: coerced to list if not already; clamped to 50 entries
Validation runs BEFORE the session lock acquire / save.
Adds tests/test_stage326_composer_draft_validation.py with 5 guards.
Verdict from Opus advisor on stage-326: SHIP-WITH-FIXES.
This commit applies the required + recommended fixes; #1957 hardening
fixed in a prior stage commit.
8782fd2675