fix: defer message_end until all content blocks are closed#37
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The assistant SDK event can arrive before all content_block_stop events have fired, especially with streaming-input mode. When message_end was emitted immediately on assistant, finishCurrent() froze in-flight blocks with done=false, empty toolInput, and no toolResult — tool pills showed "Running..." permanently and text blocks got orphaned. Track openBlockCount (incremented on content_block_start, decremented on content_block_stop). When assistant arrives, stash the message_end payload and only flush it once openBlockCount reaches zero. This guarantees every block receives its block_end before the message is finalized. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> Made-with: Cursor
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Summary
The
assistantSDK event can fire before allcontent_block_stopevents, especially with streaming-input mode. This caused two bugs:message_endtriggeredfinishCurrent()which froze in-flight blocks withdone=false, emptytoolInput, notoolResult. Tool pills showed "Running..." permanently and text blocks got orphaned.toolInputanddoneonly arrive onblock_end. Ifblock_endraces aftermessage_end, the pill never updates.Both bugs are one fix: track
openBlockCount(incremented oncontent_block_start, decremented oncontent_block_stop). Whenassistantarrives, stash themessage_endpayload and only flush onceopenBlockCounthits zero.Diagnosed collaboratively — the Mitzo phone agent identified the root cause during a live debugging session.
Test plan
block_endprecedesmessage_endwhenassistantfires early)tsc --noEmitclean, pre-commit hooks passmessage_endMade with Cursor