The Promise.withResolvers signal resolved inside the scripted model
response fires before the loop can possibly dispatch the tool, so the
parked-state assertions passed even with parking disabled (verified by
simulation: 20/20 green with waitUntilResumed stubbed out). Resolve the
readiness signal from a test-local wrap of agentPauseGate.waitUntilResumed
instead: deterministic (no wall-clock race with the cold yieldIfDue
timer), immune to sibling restoreAllMocks (manual patch, restored in
finally), and a non-parking regression now hangs the await and fails
the test.