A one-shot grok run that hit an xAI 429 exited without a terminal verb; the
dispatcher then re-spawned the same task every tick (429 -> exit -> respawn), a
container/token/cost loop with no living agent to call i_am_blocked.
- entrypoint: detect a rate-limit signature in the run output and exit 75
(EX_TEMPFAIL); a rate-limited task is NOT substituted — it must be retried.
- _handle_stopped_container: on a grok exit 75, park the provider via the
rate-limit tracker (retry_after window) instead of crash-retrying, and don't
count it as a crash. The existing probe-resume loop clears the park after the
window (unknown-provider time-expiry fallback) and the task is retried.
- spawn_agent: a grok-only, fail-open guard skips the launch while the provider
is parked, so the dispatcher no-ops instead of looping. The Claude path is
untouched.
Targeted gate green (ruff/mypy/xenon + new rate-limit tests; bash -n on the
entrypoint).
