When a watchdog (TTFB / stream-idle / stale-call) force-closes a Codex
Responses request, the worker thread can still be draining SSE frames.
`_consume_codex_event_stream` returns `status=terminal_status`, which defaults
to `"completed"`, and its only truncation guard is
`if not saw_terminal and not output`. A mid-stream kill leaves
`saw_terminal=False` but `output`/text non-empty, so the partial text came back
as a `finish_reason=stop` response and got persisted as a finished assistant
turn — a long reply just stops mid-sentence with no error surfaced.
Observed as a long generation dying at `1. Create (6/6)` and never emitting its
end marker, with the truncated text already stored in state.db.
Fix: publish a per-request retirement token so the worker can tell it has been
retired.
- `agent/chat_completion_helpers.py`: `interruptible_api_call` installs
`agent._active_codex_stream_request_token` before handing off to the worker
(codex_responses only) and clears it at all four kill sites plus the worker's
own `finally`. Retirement is cleared BEFORE `_close_request_client_once`,
which can raise — every other call site wraps it in try/except, and a leaked
token would let a later worker mistake itself for the owning attempt. The
request-local `_codex_request_retired` mirror also swallows the transport
error our own force-close causes, so the worker's local error cannot replace
the watchdog's retryable TimeoutError (same split as `_request_cancelled`).
- `agent/codex_runtime.py`: `run_codex_stream` captures the token and raises
`TimeoutError` from `interrupt_check` when it no longer owns the request —
raising rather than breaking, because a break returns the partial `final`.
The four stream callbacks also drop post-retirement frames so an abandoned
attempt cannot stream tokens into the live turn's bubble (the gateway caches
AIAgent instances per session).
`TimeoutError` is not an httpx / ConnectionError / RuntimeError subclass, so it
passes through the four `except` clauses around the consume call untouched.
No token installed (auxiliary callers such as `handle_max_iterations` drive
`_run_codex_stream` directly) means every check passes — behavior unchanged.
Tests: 5 new cases. Retirement raises instead of returning partial output;
post-retirement deltas stop reaching callbacks; the no-token path keeps its
existing terminal-frame tolerance; the watchdog installs and clears the token;
non-codex api_modes install nothing. A `_LazyCreateStream` helper is needed
because `_FakeCreateStream` materializes events in __init__, which would run
the retirement side effect before consumption starts.
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