Fix booting slots stuck due when cooldown blocks termination

agent/nix_builder_autoscaler/tests/test_reconciler.py

@@ -228,3 +228,26 @@ def test_termination_cooldown_spaces_terminations() -> None:
     assert slot is not None
     assert slot["state"] == SlotState.TERMINATING.value
     assert runtime.terminate_calls == ["i-6", "i-7"]
+
+
+def test_booting_terminal_state_bypasses_termination_cooldown() -> None:
+    db, runtime, reconciler, clock = _make_env(termination_cooldown=30)
+
+    # Start cooldown by triggering one termination.
+    runtime.instances["i-8"] = _Instance(state="running", slot_id="slot001")
+    db.update_slot_state("slot001", SlotState.DRAINING, instance_id="i-8", lease_count=0)
+    reconciler.tick()
+    assert runtime.terminate_calls == ["i-8"]
+
+    # During cooldown, a booting slot whose instance is already terminated
+    # should be emptied immediately without waiting for cooldown expiry.
+    runtime.instances["i-9"] = _Instance(state="terminated", slot_id="slot001")
+    db.update_slot_state("slot001", SlotState.BOOTING, instance_id="i-9")
+    clock.advance(1)
+    reconciler.tick()
+
+    slot = db.get_slot("slot001")
+    assert slot is not None
+    assert slot["state"] == SlotState.EMPTY.value
+    assert slot["instance_id"] is None
+    assert runtime.terminate_calls == ["i-8"]