test(edge): add genuine EventEngine cooldown primitive test

tests/test_engine.py

@@ -47,3 +47,12 @@ def test_cooldown_suppresses_duplicate():
     _lying_track(tr, 0.7)
     again = eng.process([tr], [], now=0.7)
     assert all(e.event_type != EventType.FALL for e in again)
+
+def test_allow_cooldown_primitive():
+    eng = _engine()  # EngineConfig(camera_id="cam-01", cooldown_s=30.0)
+    key = ("FALL", 1)
+    assert eng._allow(key, now=0.0) is True      # first time allowed
+    assert eng._allow(key, now=5.0) is False     # within cooldown -> suppressed
+    assert eng._allow(key, now=40.0) is True      # after cooldown_s elapsed -> allowed again
+    # a different key is independent
+    assert eng._allow(("FALL", 2), now=5.0) is True