Port t_3778a491's in-flight stale-claim guard, absent from origin/main.
_submit_with_guard adds a job id to _running_job_ids before the future
that owns its release exists. Anything that hangs or dies between the
add and pool.submit (EAGAIN thread exhaustion on a substrate spike, or a
wedged SessionDB.__init__ on a stale sqlite flock) leaks the claim; every
later tick short-circuits with 'already running - skipping' silently - no
execution row, no last_error, no counter - until the gateway process
restarts. This wedged 4 recurring no_agent router/watchdog jobs (verdict-
router, wake-scanner, auto-review-router, blocked-task-notifier) for ~1h47m
on 2026-08-14 (t_20e23f84), cleared only by manual force-run.
- Record claim timestamp + pending-future sentinel in the same critical
section as the add; replace sentinel with the owning future after submit.
- sweep_stale_inflight() runs every tick (even idle) and force-releases
claims older than max(2*interval, 30m floor) with no live future: WARNING
cron.inflight.forced_release, get_inflight_guard_stats() counter, JSONL
record, and mark_job_run(success=False) so the wedge surfaces as last_error.
- Wrap the pre-future init (create_execution/copy_context) so an exception
there releases the claim immediately instead of leaking it.
- Finite-repeat jobs are released without mark_job_run so a forced release
never consumes a one-shot budget.
Scheduler-internal only: no provider/model routing, no credentials, no
spend, no guardrail weakening, no cron permission widening.
Tests: tests/cron/test_inflight_stale_guard.py (18), plus regression tests
for the recurring EAGAIN re-dispatch and the create_execution/pool-submit
leak paths. Full tests/cron/: 616 passed.
Teknium