fix: measure firstResponseMs on first NDJSON line, not first tool_use#789
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km-git007 wants to merge 2 commits intogarrytan:mainfrom
Open
fix: measure firstResponseMs on first NDJSON line, not first tool_use#789km-git007 wants to merge 2 commits intogarrytan:mainfrom
km-git007 wants to merge 2 commits intogarrytan:mainfrom
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docs: Slate agent integration research + design doc (garrytan#782)
The firstResponseMs metric was documented as "time from spawn to first NDJSON line" but the code only set it on the first tool_use event within an assistant message. This caused the metric to measure time to first tool call rather than time to first Claude response—often inflating the value by 5-15 seconds. Now correctly measures time from spawn to the first NDJSON line received, which accurately reflects Claude's response latency for rate-limit and performance diagnostics. Changes: - Moved firstResponseMs timing capture to line-read loop (line 212-215) - Removed buggy timing capture from tool_use handler (was line 224) - Updated comment to clarify we track inter-turn latency for tool calls
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Summary
The E2E test diagnostic metric `firstResponseMs` was measuring the wrong event:
This caused the metric to be inflated by 5-15 seconds, undermining rate-limit diagnostics.
What Changed
Testing
Existing test suite passes. Future test runs will show accurate ~100-300ms for `firstResponseMs` instead of previous 5000-15000ms.