fix: lag ratio guards only engage when churn latency is actually slow#80
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The p95/avg ratio caps fired repeatedly today on runs whose absolute latency was excellent (churn p95 of 13-17ms against a 35ms cap) because a fast baseline (~6-8ms) makes the ratio hypersensitive to a few ms of runner jitter. Six unrelated PRs burned manual re-runs on this. Ratio enforcement now additionally requires the churn result itself to be slow (p95 >= 20ms, avg >= 14ms by default, env-tunable). Real regressions on fast baselines remain caught by the untouched delta caps (+20ms p95 / +12ms avg) and absolute cap (35ms p95): a genuine 3x regression from a 7ms baseline blows the delta cap regardless.
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What this does
Stops the
tests-build-and-lagjob failing on runs whose typing latency is objectively excellent. Six unrelated PRs today failed on ratio blowups where churn p95 was 13–28ms against a 35ms cap — fast baselines make the ratio explode on a few ms of runner jitter.Summary
PROGRAMA_LAG_MIN_CHURN_*_MS_FOR_RATIO)Test Plan