Independent review of the initial startup-liveness watchdog surfaced two
P1s and three P2s. All are addressed here.
P1 — legitimate slow startups (large state.db schema migrations inside
SessionDB.__init__, which run synchronously before the loop starts) could
exceed the fixed 300s deadline and restart-loop. The watchdog now checks
process CPU time (time.process_time(), process-wide) when the deadline
expires: continuous CPU consumption means a live migration, so the deadline
is extended (with a warning log per extension). The OOF-298 deadlock class
parks every thread in futex waits and accrues ~zero CPU, so it still fires
on schedule. Documented limitation: a spinning busy-wait deadlock reads as
progress and won't fire — the observed incident class is parked threads.
P1 — import-time deadlocks were outside coverage. The implementation moved
to a stdlib-only top-level module (hermes_startup_watchdog), and
hermes_cli/main.py arms it via an argv fast-path ("gateway" + "run" in
argv) BEFORE the heavy module-level import graph. gateway/startup_watchdog
remains as a re-export shim so the intuitive import path keeps working for
the disarm site, tests, and REPL use. Import-lightness is a correctness
property, tested via AST inspection: at fire time the wedged main thread
may hold the import lock, so the fire path performs no imports on its own
thread — the lifecycle-ledger write runs on a bounded-join helper thread
and os._exit happens regardless.
P2 — disarm/fire race: the handle now has an explicit state machine
(armed → disarmed | firing) guarded by a lock; whichever transition takes
the lock first wins, so a disarm landing after deadline expiry but before
the fire transition is honored. Regression test forces the exact
interleaving by blocking inside the CPU probe.
P2 — uncovered entry points: cli.py --gateway and scripts/hermes-gateway
run_gateway() now arm the watchdog before importing the gateway graph.
hermes_cli/gateway.py run_gateway() keeps an idempotent backstop arm for
programmatic callers.
P2 — respawn-storm backoff interaction: the storm breaker's intentional
backoff sleep (up to minutes, ~zero CPU — indistinguishable from a parked
deadlock) now calls kick_startup_watchdog(extra_s=backoff) so the deadline
is pushed past the sleep instead of firing mid-backoff.
Also: the faulthandler stack dump is now additionally written to
logs/gateway-startup-watchdog.log (stderr may be absent on detached/
windowless runs); the disarm site in gateway/run.py moved inside the
loop-confirmed branch (if the loop is NOT live, the milestone was not
reached and the watchdog must stay armed); hermes_startup_watchdog added
to pyproject py-modules so sealed venvs ship it; SERVICE_RESTART_EXIT_CODE
is duplicated in the stdlib-only module with a parity test against
gateway.restart.
Tests: 38 in tests/gateway/test_startup_watchdog.py (contracts incl.
stdlib-only AST check and shim re-export identity, config resolution,
arm/disarm/kick, CPU-progress extension vs no-progress fire, probe-failure
fails toward firing, disarm-vs-fire race, dump record + file stacks,
lifecycle ledger, custom exit code).
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