test: embed-concurrent's planted-race control runs until it observes the race - #1107
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…the race The #885 control asserted that a deliberately shared global cross-talks between two threads within a fixed 200 rounds each. That is a bet on the scheduler, and it lost on CI for PR #1106 @ 07a0ac3 (2026-09-06): `control cross-talk: A=0 B=0 over 200 rounds each`, with the file identical on main and the lane green on the previous push. PR #1034 hit the same shape before the start barrier was added. Now each worker runs at least ROUNDS rounds and keeps racing until BOTH sides have observed at least one mismatch or PLANT_BUDGET (200000) rounds elapse; the check requires both sides to have seen it. The property is unchanged — a harness that never interleaves exhausts the budget and FAILS — only the sample size adapts to the scheduler. Measured on the dev box: 3/3 runs stop at the 200-round minimum (A=198/200 B=199/200; 199/198; 188/189). Plant: making the shared global `__thread` (race impossible) gives `A=0/200000 B=0/200000` and EMBED_CONCURRENT_FAIL in 0.37 s, so the budget costs nothing on a failing control either. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Kpzyjv1SaLaqBf45FSFDhB
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The #885 control bet on the scheduler (fixed 200 rounds) and lost on CI for #1106 @ 07a0ac3 with the file identical on main (
A=0 B=0 over 200 rounds each); PR #1034 saw the same shape before the barrier landed. Each worker now races until both sides have observed a mismatch or a 200000-round budget elapses; a never-interleaving harness still fails. Dev box: 3/3 stop at the 200-round minimum; a__threadplant (race impossible) fails in 0.37 s.🤖 Generated with Claude Code
https://claude.ai/code/session_01Kpzyjv1SaLaqBf45FSFDhB