Addresses the two class-level review blockers on PR #89750:
1. Bounded hard-exit seam (escort thread). The forensic fire path
(logger.critical, dump record, faulthandler, lifecycle ledger) can
itself wedge — the parked main thread may hold the logging handler
lock, or the disk may be full/hung. _fire() now starts an exit-escort
daemon thread BEFORE any forensics; it is free of log handlers,
filesystem access, module loads and application locks, and hard-exits
with the restart code after _FIRE_EXIT_BOUND_S unless the normal fire
path signals completion. Adversarial tests hold the logging handler
lock / hang the dump write at fire time and assert the exit seam is
still reached.
2. Phase-owned progress leases (report_startup_progress). Process CPU
time proves process activity, not startup progress: an unrelated busy
thread could extend forever while startup sits parked (false
negative), and I/O-bound repair/backup accrues ~zero CPU and would be
killed (false positive). Long synchronous startup phases now declare
authoritative, clamped (_MAX_LEASE_S), renewable progress leases:
state.db _init_schema + the version-gated data-migration chain
(hermes_state_schema) and repair_state_db_schema (hermes_state) are
wired. CPU progress remains only as a bounded fallback, capped at
_MAX_CPU_EXTENSIONS, with leases outranking the cap. Adversarial
tests cover both directions (lease saves zero-CPU legitimate work;
capped CPU noise no longer hides a parked deadlock).
Fire-path dump record now includes lease_count/last_lease_phase for
forensics. gateway/startup_watchdog.py shim re-exports
report_startup_progress.
OOF-298
Shannon Sands
852db61abe