The WithCancelCause+timer rewrite made MaxRuntime surface as Canceled (not
DeadlineExceeded), so statusFor's context.Cause(DeadlineExceeded) check could
relabel (a) a genuine run error as 'timeout' and (b) a caller cancel/deadline as
'timeout' (was 'cancelled'). Convergent gadfly finding (glm-5.2 + cluster).
Fix: keep MaxRuntime as WithTimeout (its DeadlineExceeded propagates → 'timeout',
preserving own-timeout vs caller-cancel), add a NESTED WithCancelCause layer only
for the kill. statusFor consults context.Cause ONLY for ErrCriticKill; everything
else is classified by the run error itself. Tests: generic-error-not-relabeled +
caller-cancel-stays-cancelled.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
steve
be4bbbcad5