ScriptRunGuard counts a run on StartedRunCount and InFlightCount together the
moment it is admitted, but releases InFlightCount only in the run's finally.
The runaway test waited on StartedRunCount >= 6 and then asserted
InFlightCount == 1, so the healthy sibling's 4th-push run - admitted but still
executing - was counted alongside the runaway orphan (2). Test race, not an
engine defect: widening only the healthy run reproduced it 5/5.
- wait until StartedRunCount == 6 AND InFlightCount == 1
- healthy predicate spins ~100 ms so the window is open on every run
- positive controls: the final push must be refused once more (the in-flight
run is the orphan) and the quality-once absence check runs only after the
healthy Activated event from the later pass has been delivered
Under 28 busy-loops on 14 cores: before 2/60 failed, after 0/60.
Joseph Doherty
f1da809f3c