fix(transcript_mirror): handle CancelledError in eager-flush done callback#931
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ashwin-ant merged 1 commit intoMay 14, 2026
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…lback The ``add_done_callback`` lambda on the eager-flush ``_flush_task`` called ``t.exception()`` unconditionally. In Python 3.8+, ``Task.exception()`` raises ``CancelledError`` for cancelled tasks, and the raise from inside a done-callback surfaces as a noisy "Exception in callback" log every time the SDK shuts down with pending eager flushes (visible in anthropics#928's failing-test traceback). Replace the lambda with a module-level ``_swallow_done_exception`` helper that no-ops on cancelled tasks and otherwise retrieves the exception so asyncio doesn't warn about an unretrieved exception on a fire-and-forget task. Closes anthropics#930 Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
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…ic wait (#933) ## Summary Fixes #928. The two eager-flush tests assumed 2 `await asyncio.sleep(0)` yields between consecutive `enqueue` calls were enough for each drain to complete and append. Under lock contention between drains the path from `enqueue` to `store.append` needs ~4 turns (drain releases lock → next drain acquires it → `wait_for(store.append)` schedules its inner task → record). Both tests fail 5/5 locally on Python 3.11.14 / macOS arm64; CI got lucky on event-loop scheduling at merge time of #905. See #928 for the full probe and yield-count sweep. ## Changes ### Unit-level test (`test_eager_mode_flushes_per_frame`) Replace fixed `sleep(0)` count with a new `_wait_until(predicate, timeout=1.0)` helper that yields until `len(store.append_calls)` reaches the expected value, with a 1-second deadline. Deterministic — works regardless of Python / pytest-asyncio / OS scheduling differences. ### Integration-level test (`test_eager_flush_mode_appends_per_frame_before_result`) Convert `_make_mock_transport`'s `yield_between: bool` to `yields_between: int` (default `0`) and pass `yields_between=10` for this test, so the mock yields the loop enough times between frames for each eager flush to drain before the next frame arrives. Robust headroom — 4 was the observed minimum, 10 leaves room for slower environments. The signature change touches only one caller (this same test); other callers omit the parameter and behave identically to before. ## Test plan - [x] `for i in 1 2 3 4 5; do uv run pytest <both tests> -q; done` → 5/5 passed (was 5/5 failed before) - [x] `uv run pytest tests/test_transcript_mirror.py` → 42/42 passed - [x] `ruff check / ruff format` clean ## Related issues / PRs - Filed alongside two other fixes from the same audit pass: #929 (stderr callback swallow → PR #932), #930 (cancellation log noise → PR #931). Independent of those. Co-authored-by: Xian Zheng <xian.zheng@challenger.gauntletai.com> Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
Fixes #930.
The
add_done_callbacklambda on the eager-flush_flush_taskcalledt.exception()unconditionally. In Python 3.8+,Task.exception()raisesCancelledErrorfor cancelled tasks, and the raise from inside a done-callback surfaces as a noisyException in callbacklog every time the SDK shuts down with pending eager flushes — visible in #928's failing-testCaptured log teardownblock.Changes
src/claude_agent_sdk/_internal/transcript_mirror_batcher.py: replacelambda t: t.exception()with a module-level_swallow_done_exceptionhelper that no-ops on cancelled tasks and otherwise retrieves the exception so asyncio doesn't warn.tests/test_transcript_mirror.py: addTestSwallowDoneExceptionwith three cases — cancelled task (must not raise), failed task (retrieves exception, doesn't re-raise), successful task (no-op).Test plan
uv run pytest tests/test_transcript_mirror.py::TestSwallowDoneException— 3 passeduv run mypy src/— cleanruff check / ruff format— cleanNotes
The fix is intentionally narrow — same call site, same intent (silence "Task exception was never retrieved" warnings), just cancellation-safe. No behavior change on the happy path.