The aborted-mid-stream case raced the abort against the child's chunk
delivery across two pipes and lost under full-suite load. Replace it with a
same-pipe ordering probe: the fake streams one text-delta chunk and then
answers the prompt with a malformed (non-accepted) result, so frame order
guarantees the chunk precedes the failure — the accumulated partial text
must survive into the error result. Same code path (collectOutput without a
complete assistant/message), no timing window.
Tianyi Cui
1ad0f26b92