feat(snap-receiver): implement snap detection, position snapping, and pose animation trigger

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

test/unit/test_snap_receiver.gd

@@ -0,0 +1,82 @@
+## Tests for SnapReceiver — snap detection when Character is released near a SnapPoint.
+extends GutTest
+
+var _char: Character
+var _snap: SnapPoint
+
+
+func before_each() -> void:
+	_char = preload("res://scenes/characters/Character.tscn").instantiate() as Character
+	add_child_autofree(_char)
+	_snap = SnapPoint.new()
+	_snap.pose = "sitting"
+	add_child_autofree(_snap)
+
+
+func _get_receiver() -> SnapReceiver:
+	return _char.get_node("SnapReceiver") as SnapReceiver
+
+
+func test_snap_receiver_exists_on_character() -> void:
+	assert_not_null(_get_receiver())
+
+
+func test_no_current_snap_initially() -> void:
+	assert_null(_get_receiver().get_current_snap())
+
+
+func test_snap_detected_when_character_released_within_radius() -> void:
+	_snap.global_position = Vector2(0.0, 0.0)
+	_char.global_position = Vector2(50.0, 0.0)
+	_get_receiver()._on_drag_released(Vector2(50.0, 0.0))
+	assert_eq(_get_receiver().get_current_snap(), _snap)
+
+
+func test_no_snap_when_released_outside_radius() -> void:
+	_snap.global_position = Vector2(0.0, 0.0)
+	_char.global_position = Vector2(200.0, 0.0)
+	_get_receiver()._on_drag_released(Vector2(200.0, 0.0))
+	assert_null(_get_receiver().get_current_snap())
+
+
+func test_character_position_set_to_snap_point_on_snap() -> void:
+	_snap.global_position = Vector2(100.0, 100.0)
+	_char.global_position = Vector2(120.0, 100.0)
+	_get_receiver()._on_drag_released(Vector2(120.0, 100.0))
+	assert_eq(_char.global_position, Vector2(100.0, 100.0))
+
+
+func test_character_animation_set_to_snap_pose_on_snap() -> void:
+	_snap.global_position = Vector2(0.0, 0.0)
+	_snap.pose = "lying"
+	_char.global_position = Vector2(50.0, 0.0)
+	_get_receiver()._on_drag_released(Vector2(50.0, 0.0))
+	assert_eq(_char.get_animation_state(), "lying")
+
+
+func test_pickup_clears_current_snap() -> void:
+	_snap.global_position = Vector2(0.0, 0.0)
+	_char.global_position = Vector2(50.0, 0.0)
+	_get_receiver()._on_drag_released(Vector2(50.0, 0.0))
+	_get_receiver()._on_drag_picked_up(Vector2(50.0, 0.0))
+	assert_null(_get_receiver().get_current_snap())
+
+
+func test_pickup_frees_snap_point() -> void:
+	_snap.global_position = Vector2(0.0, 0.0)
+	_char.global_position = Vector2(50.0, 0.0)
+	_get_receiver()._on_drag_released(Vector2(50.0, 0.0))
+	_get_receiver()._on_drag_picked_up(Vector2(50.0, 0.0))
+	assert_true(_snap.is_free())
+
+
+func test_second_character_cannot_snap_to_occupied_point() -> void:
+	_snap.global_position = Vector2(0.0, 0.0)
+	_char.global_position = Vector2(50.0, 0.0)
+	_get_receiver()._on_drag_released(Vector2(50.0, 0.0))
+	var char2: Character = preload("res://scenes/characters/Character.tscn").instantiate() as Character
+	add_child_autofree(char2)
+	char2.global_position = Vector2(60.0, 0.0)
+	var recv2: SnapReceiver = char2.get_node("SnapReceiver") as SnapReceiver
+	recv2._on_drag_released(Vector2(60.0, 0.0))
+	assert_null(recv2.get_current_snap())