Fix daily run-ceiling race under concurrent event arrival

[deephazar-eva-ai]

What breaks

AutonomyGovernor.admit_run checked window_count(...) < max_runs_per_day and returned an admitted verdict, but the matching increment (governor.record(subscription_id, kind="run", ...)) only happened in AutonomousEventEngine.process after runtime.run() completed. The check is a read, the increment is a write, and nothing held them together. Two events matching the same subscription that arrive close enough together — two webhook deliveries in one burst, a cron tick racing a retried tick — can both do their read before either does its write: both see the window under the ceiling, both get admitted, and the ceiling is exceeded by however many requests raced it.

This is the concurrent counterpart to a control the codebase already takes seriously in sequence (see test_a_daily_run_ceiling_bounds_an_agent_that_starts_its_own_runs) — the ceiling just never held once two requests could overlap in time, which is exactly the shape of traffic an unattended, event-driven agent actually receives.

The test that shows it breaking

tests/test_run_ceiling_concurrency.py::test_a_daily_run_ceiling_holds_when_events_arrive_concurrently sets max_runs_per_day=1, then fires five events matching the subscription through engine.process() concurrently via asyncio.gather, against a runtime whose run() takes a real (if brief) amount of time.

• Before this fix: assert len(runtime.runs) == 1 fails — assert 5 == 1. All five runs started.
• After this fix: passes. Exactly one run starts; the other four are refused with max_runs_per_day.

The fix

EventStore.try_reserve() checks the ceiling and claims one unit against it inside a single lock acquisition, so admit_run() reserves a run's slot atomically at admission time instead of trusting a separate write after the run finishes. window_record() gains an optional count= parameter (default 1, unchanged for every other caller) so the completion-time record() call can add the run's actual spend without double-counting a slot already claimed at admission. A reservation that turns out not to be used — the slot was claimed but the daily_budget check then refused the run anyway — is given back via release_reservation() rather than silently wasted.

Side effect worth flagging: a run that starts and then raises is now counted (the slot was claimed at admission), where before it wasn't (the count only incremented after runtime.run() returned successfully). A ceiling that bounds attempts rather than only completions is the more defensible reading for a control meant to stop unbounded spend or unbounded action — a run that fails after doing real work still did that work.

Not fixed here, flagged as a follow-up: admit_run's daily_budget check (a spend ceiling, not a count ceiling) has the same shape of race. Closing it precisely means reserving against an unknown final cost rather than a known count of 1 — a bigger change than this bug's scope.

Test plan

• pytest tests/test_run_ceiling_concurrency.py — new regression test, passes
• pytest tests/test_autonomy_governor.py — existing governor/ceiling coverage, still green (11/11)
• pytest -q — full suite green, 356 passed
• ruff check — clean on all changed files

[theschoolofai]

Session 16 — graded

Score: 0.

Duplicate of #3, filed 2026-08-09 against this one's 08-15. Same run-ceiling race under concurrent arrival.

[theschoolofai]

Session 16 — regraded ✅

Score: +100. The verdict below stands: this is a duplicate of an earlier filing (or, for glc_v5 #23, an enhancement rather than a defect), and it is recorded as such.

What has changed is the credit. On review, the work here was genuinely done: the bug was found independently, the reproduction is real and the fix is sound. Losing a race you had no way of seeing is not a reason to earn nothing, so this is credited at the full 100 even though it does not carry the first-to-file claim.

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Original assessment, unchanged:

Duplicate of #3, filed 2026-08-09 against this one's 08-15. Same run-ceiling race under concurrent arrival.