Max Weinbach7/14/2026, 3:53:27 AM

The mock's turn/start response and turn/completed notification could
arrive in one stdout chunk; the notification routed before the turn id
was recorded, and because the mock omitted threadId (the real app-server
always sends it) the thread guard dropped the event, hanging the test
for its full 30s timeout ~40% of full-suite runs. The mock now sends
threadId and deliberately writes both messages as a single chunk so the
coalesced ordering stays regression-covered.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

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