The per-chunk timeout exists so a bad chunk fails loudly 'rather than
silently burn the job's wall-clock budget until the CI runner cancels the
whole job' (run-tests.cjs:633-637). The control flow defeated that: after a
timeout kill the loop fell through to the next chunk. Since the timeout
(600000ms) is half the 20m job cap and a healthy Windows full pass is
~11m42s, continuing after a timeout can essentially never finish.
Observed on run 29749380190 (windows shard 2/3): chunk 1/5 was killed at
exactly 600s, the loop pressed on through chunks 2-4, and the job was
cancelled mid-chunk-5 at the 20m wall. The failure surfaced as
'##[error]The operation was canceled.' — the timeout diagnostic ended up
~38,000 log lines from the end and 'gh run view --log-failed' returned
nothing, making the real cause very hard to find.
Abort the remaining chunks on a timeout so the diagnostic survives as the
visible failure. Ordinary test failures still run every chunk, so the
operator keeps seeing all failures in one pass.
Fixes#2455
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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