run_coroutine_threadsafe refused it and it was never awaited, a RuntimeWarning under pytest 9. The cancel still logs that it could not reach the worker. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WgBfkm4rCmtd1T4vHWjEPx