fix(playable): close release validation lifecycle gaps

project/playable_harness_test.gd

@@ -203,10 +203,24 @@ func valid_config() -> Dictionary:
 		"resolution": [1280, 720], "loops": 1, "timeout_seconds": 900,
 	}
 
+func test_probe_releases_old_registries() -> void:
+	var observer := Probe.new()
+	for i in range(30):
+		var registry := FakeFx.new()
+		var reference: WeakRef = weakref(registry)
+		observer.watch_local(registry, "fx_spawned", "fx_spawned")
+		observer.watch_local(registry, "fx_finished", "fx_finished")
+		check(observer.bound_count() == 2, "probe prunes old scene bindings")
+		registry = null
+		check(reference.get_ref() == null, "probe does not retain the old scene's effect registry")
+	observer.disconnect_all()
+	observer.free()
+
 func run() -> void:
 	MapCoord.set_base(Vector2.ZERO)
 	test_config_contract()
 	test_report_contract()
+	test_probe_releases_old_registries()
 	test_happy_path()
 	test_gameplay_not_allowed()
 	test_absent_slot_fails_without_select()

project/testing/playable_probe.gd

@@ -77,7 +77,7 @@ func snapshot() -> Dictionary:
 
 func disconnect_all() -> void:
 	for entry in _connections:
-		var source: Object = entry.source
+		var source: Object = entry.source.get_ref()
 		var signal_name: String = entry.signal
 		var callback: Callable = entry.callback
 		if source != null and is_instance_valid(source) and source.has_signal(signal_name) \
@@ -86,15 +86,24 @@ func disconnect_all() -> void:
 	_connections.clear()
 
 func bound_count() -> int:
+	_prune_connections()
 	return _connections.size()
 
+func _prune_connections() -> void:
+	for i in range(_connections.size() - 1, -1, -1):
+		if _connections[i].source.get_ref() == null:
+			_connections.remove_at(i)
+
 func _exit_tree() -> void:
 	disconnect_all()
 
 func _bind(source: Object, signal_name: String, callback: Callable) -> void:
+	# Registries are RefCounted and own parsed effect caches. Observing a scene
+	# must not keep it alive after reconnect; discard dead bindings on rebind.
+	_prune_connections()
 	if source.has_signal(signal_name) and not source.is_connected(signal_name, callback):
 		source.connect(signal_name, callback)
-		_connections.append({"source": source, "signal": signal_name, "callback": callback})
+		_connections.append({"source": weakref(source), "signal": signal_name, "callback": callback})
 
 func _emit(kind: String, payload := {}, actor_vid := 0, target_vid := 0) -> void:
 	var data: Dictionary = payload.duplicate(true)