feat(studio,stacking,animations,collections): M16 ModBison Studio, object stacking, model animations, and poly collections for MVP 2

scripts/smoke_test_studio_playtest.gd

@@ -0,0 +1,105 @@
+extends SceneTree
+## Headless smoke test for Studio simulation harness, playtest transition,
+## avatar spawn, and clean edit mode restoration (Task f77bf388e8b4).
+
+var _failures: int = 0
+var _checks: int = 0
+
+const StudioSimulationManagerClass = preload("res://scripts/studio/studio_simulation_manager.gd")
+const ObjectMotionComponentClass = preload("res://scripts/components/object_motion_component.gd")
+
+func _init() -> void:
+	print("--- Running Smoke Test: Studio Simulation Harness & Playtest ---")
+	test_playtest_lifecycle()
+	test_state_rollback_on_stop()
+
+	if _failures == 0:
+		print("--- PASS: All %d studio playtest checks passed! ---" % _checks)
+		quit(0)
+	else:
+		printerr("--- FAIL: %d failures out of %d checks ---" % [_failures, _checks])
+		quit(1)
+
+
+func _check(desc: String, cond: bool) -> void:
+	_checks += 1
+	if cond:
+		print("  ✓ %s" % desc)
+	else:
+		_failures += 1
+		printerr("  ✗ FAIL: %s" % desc)
+
+
+func _make_mock_core() -> EditorCore:
+	var payload := ChunkDataDecoder.ChunkPayload.new()
+	var layer := ChunkDataDecoder.TileLayerData.new()
+	layer.name = "ground"
+	layer.layer_id = 0
+	layer.width = 16
+	layer.height = 16
+	layer.depth = 1
+	layer.tiles = PackedInt32Array()
+	layer.tiles.resize(16 * 16)
+	payload.tile_layers.append(layer)
+
+	var model := ChunkEditorModel.new(payload)
+	var catalog := EditorObjectCatalog.new()
+	catalog.load_catalog()
+	return EditorCore.new(model, catalog)
+
+
+func test_playtest_lifecycle() -> void:
+	print("Testing Simulation transition (Edit -> Play -> Stop)...")
+	var core := _make_mock_core()
+	var world := Node3D.new()
+	root.add_child(world)
+
+	var sim := StudioSimulationManagerClass.new()
+	world.add_child(sim)
+	sim.setup(core, world)
+
+	_check("Initial state is EDIT mode", sim.is_editing())
+	_check("is_playing returns false", not sim.is_playing())
+
+	# Start Play
+	sim.start_play(true)
+	_check("State transitioned to PLAYING", sim.is_playing())
+	_check("Test avatar spawned in world", sim._spawned_avatar != null)
+
+	# Stop Play
+	sim.stop_simulation()
+	_check("State restored to EDIT mode", sim.is_editing())
+	_check("Test avatar despawned cleanly", sim._spawned_avatar == null)
+
+	world.queue_free()
+
+
+func test_state_rollback_on_stop() -> void:
+	print("Testing world object transform snapshot and clean rollback...")
+	var core := _make_mock_core()
+	var world := Node3D.new()
+	root.add_child(world)
+
+	# Place an initial object at (5, 5, 0)
+	var obj_id := core.place_object("crate_small", Vector3(5, 5, 0))
+	_check("Placed initial crate at (5, 5, 0)", obj_id != "")
+
+	var sim := StudioSimulationManagerClass.new()
+	world.add_child(sim)
+	sim.setup(core, world)
+
+	# Start Play (takes snapshot of (5, 5, 0))
+	sim.start_play(false)
+
+	# Simulate movement during gameplay (e.g. physics push or script motion to (20, 30, 10))
+	var obj = core.model.find_object(obj_id)
+	obj.position = Vector3(20, 30, 10)
+	_check("Object moved during gameplay to (20, 30, 10)", obj.position.is_equal_approx(Vector3(20, 30, 10)))
+
+	# Stop Play -> triggers snapshot rollback
+	sim.stop_simulation()
+
+	_check("Object restored exactly to pre-play position (5, 5, 0)",
+		obj.position.is_equal_approx(Vector3(5, 5, 0)))
+
+	world.queue_free()