feat(M03): add entity presentation facade

src/render/entities/entity_presentation_snapshot.gd

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+class_name EntityPresentationSnapshot
+extends RefCounted
+
+## Immutable renderer input for one session-local world entity visual.
+## Gameplay authority, identity allocation and asset selection remain external.
+
+const CONTRACT_VERSION := 1
+const SCRIPT_PATH := "res://src/render/entities/entity_presentation_snapshot.gd"
+const ENTITY_ID_SCRIPT := preload("res://src/domain/identity/entity_id.gd")
+const GODOT_WORLD_POSITION_SCRIPT := preload("res://src/domain/coordinates/godot_world_position.gd")
+
+var is_valid: bool:
+	get:
+		return _failure_code.is_empty()
+
+var failure_code: StringName:
+	get:
+		return _failure_code
+
+var entity_id: RefCounted:
+	get:
+		return _entity_id
+
+var world_position: RefCounted:
+	get:
+		return _world_position
+
+var visual_scene_path: String:
+	get:
+		return _visual_scene_path
+
+var yaw_radians: float:
+	get:
+		return _yaw_radians
+
+var uniform_scale: float:
+	get:
+		return _uniform_scale
+
+var is_visible: bool:
+	get:
+		return _is_visible
+
+var _failure_code: StringName
+var _entity_id: RefCounted
+var _world_position: RefCounted
+var _visual_scene_path: String
+var _yaw_radians: float
+var _uniform_scale: float
+var _is_visible: bool
+
+
+## Creates a version-1 full visual snapshot. Invalid values remain inspectable and
+## are rejected without scene mutation by the facade/presenter.
+static func create(
+		entity_id_value: RefCounted,
+		world_position_value: RefCounted,
+		visual_scene_path_value: String,
+		yaw_radians_value: float = 0.0,
+		uniform_scale_value: float = 1.0,
+		is_visible_value: bool = true
+) -> RefCounted:
+	return load(SCRIPT_PATH).new(
+		entity_id_value,
+		world_position_value,
+		visual_scene_path_value,
+		yaw_radians_value,
+		uniform_scale_value,
+		is_visible_value
+	)
+
+
+func _init(
+		entity_id_value: RefCounted,
+		world_position_value: RefCounted,
+		visual_scene_path_value: String,
+		yaw_radians_value: float,
+		uniform_scale_value: float,
+		is_visible_value: bool
+) -> void:
+	_entity_id = entity_id_value
+	_world_position = world_position_value
+	_visual_scene_path = visual_scene_path_value.strip_edges()
+	_yaw_radians = yaw_radians_value
+	_uniform_scale = uniform_scale_value
+	_is_visible = is_visible_value
+	_failure_code = _validate()
+
+
+func _validate() -> StringName:
+	if _entity_id == null or _entity_id.get_script() != ENTITY_ID_SCRIPT or not bool(_entity_id.call("is_valid")):
+		return &"entity_presentation_invalid_entity_id"
+	if _world_position == null or _world_position.get_script() != GODOT_WORLD_POSITION_SCRIPT:
+		return &"entity_presentation_invalid_world_position"
+	for coordinate_name in [&"x_units", &"y_units", &"z_units"]:
+		if not is_finite(float(_world_position.get(coordinate_name))):
+			return &"entity_presentation_position_not_finite"
+	if _visual_scene_path.is_empty():
+		return &"entity_presentation_visual_path_empty"
+	if not is_finite(_yaw_radians):
+		return &"entity_presentation_yaw_not_finite"
+	if not is_finite(_uniform_scale) or _uniform_scale <= 0.0:
+		return &"entity_presentation_scale_invalid"
+	return &""

src/render/entities/entity_presentation_snapshot.gd.uid

@@ -0,0 +1 @@
+uid://djvnorls0yf06

src/render/entities/world_entity_presenter.gd

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+@tool
+class_name WorldEntityPresenter
+extends Node3D
+
+## Main-thread owner of visual subtrees for session-local world entities.
+## The full immutable snapshot is reapplied idempotently by entity identity.
+
+const ENTITY_PRESENTATION_SNAPSHOT_SCRIPT := preload("res://src/render/entities/entity_presentation_snapshot.gd")
+const ENTITY_ID_SCRIPT := preload("res://src/domain/identity/entity_id.gd")
+
+var _presented_entities: Dictionary = {}
+
+
+## Creates or updates one entity visual. A changed visual path is instantiated
+## successfully before the previous subtree is detached, so failed replacement
+## retains the last valid presentation.
+func present_entity(entity_presentation_snapshot: RefCounted) -> bool:
+	if not _is_valid_snapshot(entity_presentation_snapshot):
+		return false
+	var entity_id: RefCounted = entity_presentation_snapshot.get("entity_id")
+	var entity_key := _entity_key(entity_id)
+	var visual_scene_path := String(entity_presentation_snapshot.get("visual_scene_path"))
+	var current_entry: Dictionary = _presented_entities.get(entity_key, {})
+	var visual_root := current_entry.get("visual_root") as Node3D
+	if visual_root == null or not is_instance_valid(visual_root) or String(current_entry.get("visual_scene_path", "")) != visual_scene_path:
+		var replacement_root := _instantiate_visual_root(entity_id, visual_scene_path)
+		if replacement_root == null:
+			return false
+		if visual_root != null and is_instance_valid(visual_root):
+			remove_child(visual_root)
+		add_child(replacement_root)
+		_apply_snapshot_transform(replacement_root, entity_presentation_snapshot)
+		if visual_root != null and is_instance_valid(visual_root):
+			visual_root.queue_free()
+		visual_root = replacement_root
+	else:
+		_apply_snapshot_transform(visual_root, entity_presentation_snapshot)
+	_presented_entities[entity_key] = {
+		"visual_root": visual_root,
+		"visual_scene_path": visual_scene_path,
+		"snapshot": entity_presentation_snapshot,
+	}
+	return true
+
+
+## Removes one owned entity visual. Returns false for an invalid/unknown identity.
+func remove_entity(entity_id: RefCounted) -> bool:
+	if entity_id == null or entity_id.get_script() != ENTITY_ID_SCRIPT or not bool(entity_id.call("is_valid")):
+		return false
+	var entity_key := _entity_key(entity_id)
+	if not _presented_entities.has(entity_key):
+		return false
+	var entry: Dictionary = _presented_entities[entity_key]
+	var visual_root := entry.get("visual_root") as Node3D
+	_presented_entities.erase(entity_key)
+	if visual_root != null and is_instance_valid(visual_root):
+		remove_child(visual_root)
+		visual_root.queue_free()
+	return true
+
+
+## Returns detached scalar diagnostics without exposing owned Nodes or snapshots.
+func entity_presentation_snapshot() -> Dictionary:
+	var entities: Array[Dictionary] = []
+	var sorted_entity_keys: Array = _presented_entities.keys()
+	sorted_entity_keys.sort()
+	for entity_key_variant in sorted_entity_keys:
+		var entity_key := String(entity_key_variant)
+		var entry: Dictionary = _presented_entities[entity_key]
+		var snapshot: RefCounted = entry.get("snapshot")
+		entities.append({
+			"entity_key": entity_key,
+			"visual_scene_path": String(entry.get("visual_scene_path", "")),
+			"visible": bool(snapshot.get("is_visible")),
+		})
+	return {
+		"contract_version": ENTITY_PRESENTATION_SNAPSHOT_SCRIPT.CONTRACT_VERSION,
+		"entity_count": entities.size(),
+		"entities": entities,
+	}
+
+
+func _exit_tree() -> void:
+	_presented_entities.clear()
+
+
+func _is_valid_snapshot(entity_presentation_snapshot: RefCounted) -> bool:
+	return (
+		entity_presentation_snapshot != null
+		and entity_presentation_snapshot.get_script() == ENTITY_PRESENTATION_SNAPSHOT_SCRIPT
+		and bool(entity_presentation_snapshot.get("is_valid"))
+	)
+
+
+func _entity_key(entity_id: RefCounted) -> String:
+	return String(entity_id.call("to_debug_key"))
+
+
+func _instantiate_visual_root(entity_id: RefCounted, visual_scene_path: String) -> Node3D:
+	if not ResourceLoader.exists(visual_scene_path, "PackedScene"):
+		push_warning("WorldEntityPresenter cannot find visual scene: %s" % visual_scene_path)
+		return null
+	var visual_scene := load(visual_scene_path) as PackedScene
+	if visual_scene == null:
+		push_warning("WorldEntityPresenter cannot load visual scene: %s" % visual_scene_path)
+		return null
+	var visual_instance := visual_scene.instantiate()
+	if not (visual_instance is Node3D):
+		visual_instance.free()
+		push_warning("WorldEntityPresenter visual scene root is not Node3D: %s" % visual_scene_path)
+		return null
+	var visual_root := visual_instance as Node3D
+	visual_root.name = "EntityVisual_%020d" % int(entity_id.get("session_sequence"))
+	return visual_root
+
+
+func _apply_snapshot_transform(visual_root: Node3D, entity_presentation_snapshot: RefCounted) -> void:
+	var world_position: RefCounted = entity_presentation_snapshot.get("world_position")
+	var position_units := Vector3(
+		float(world_position.get("x_units")),
+		float(world_position.get("y_units")),
+		float(world_position.get("z_units"))
+	)
+	var uniform_scale := float(entity_presentation_snapshot.get("uniform_scale"))
+	var yaw_radians := float(entity_presentation_snapshot.get("yaw_radians"))
+	visual_root.global_transform = Transform3D(
+		Basis(Vector3.UP, yaw_radians).scaled(Vector3.ONE * uniform_scale),
+		position_units
+	)
+	visual_root.visible = bool(entity_presentation_snapshot.get("is_visible"))

src/render/entities/world_entity_presenter.gd.uid

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+uid://b0keiyi1wuu5i