Joseph Doherty
84dbf20a43
A WriteAsync/WriteBatchAsync caller cancelled after the draining lock-holder claimed its frame unwinds without awaiting that frame's completion; the same holds for a frame already faulted by a concurrent FailAllQueued, where TrySetCanceled loses. A later wire-write failure then lands TrySetException on a task with no awaiter and surfaces as TaskScheduler.UnobservedTaskException. The tombstone helpers now attach a fault-observing continuation to every frame in the cancelled call (a cancelled task never fires OnlyOnFaulted, so unconditional attach is safe), outside _gate because an already-faulted task runs the continuation inline. NEXT-05 is resolved as a documented decision, not a code change: tombstoned entries keep their lazy DequeueNext purge — any subsequent write drains both queues to empty and the heartbeat loop bounds residency to one interval, while eager Queue<T> rebuilds under _gate would add ordering-invariant surface for no gain. Rationale recorded in docs/WorkerFrameProtocol.md alongside the WRK-22 residual-window contract. New regression test drives the exact abandonment: gated stream holds writer A mid-write, the queued event frame is claimed and blocked mid-write, its caller is cancelled, the write then faults with a marker exception, and the test asserts the marker never reaches UnobservedTaskException after a forced GC. net48 x86 build/test runs on windev with the rest of this batch.