render: extract M2 build dispatch planner

src/render/m2/m2_build_dispatch_planner.gd

@@ -0,0 +1,48 @@
+class_name M2BuildDispatchPlanner
+extends RefCounted
+
+## Selects the next M2 build action from already observed resource state.
+## The planner retains no state or engine-object references.
+
+const ACTION_WAIT_FOR_ANIMATION := &"wait_for_animation"
+const ACTION_MATERIALIZE_ANIMATED := &"materialize_animated"
+const ACTION_WAIT_FOR_STATIC_MESH := &"wait_for_static_mesh"
+const ACTION_MATERIALIZE_STATIC := &"materialize_static"
+const ACTION_ADVANCE_WITHOUT_MATERIALIZATION := &"advance_without_materialization"
+
+
+## Returns a detached action/transition plan for one M2 build operation.
+func plan_step(
+	batch_count: int,
+	animation_request_pending: bool,
+	has_animated_prototype: bool,
+	has_static_mesh: bool,
+	static_model_missing: bool
+) -> Dictionary:
+	if animation_request_pending:
+		return _wait_plan(ACTION_WAIT_FOR_ANIMATION)
+	if batch_count <= 0:
+		return _advance_plan(ACTION_ADVANCE_WITHOUT_MATERIALIZATION, false)
+	if has_animated_prototype:
+		return _advance_plan(ACTION_MATERIALIZE_ANIMATED, true)
+	if has_static_mesh:
+		return _advance_plan(ACTION_MATERIALIZE_STATIC, true)
+	if static_model_missing:
+		return _advance_plan(ACTION_ADVANCE_WITHOUT_MATERIALIZATION, true)
+	return _wait_plan(ACTION_WAIT_FOR_STATIC_MESH)
+
+
+func _wait_plan(action: StringName) -> Dictionary:
+	return {
+		"action": action,
+		"rotate_queue": true,
+		"increment_batch_serial": false,
+	}
+
+
+func _advance_plan(action: StringName, increment_batch_serial: bool) -> Dictionary:
+	return {
+		"action": action,
+		"rotate_queue": false,
+		"increment_batch_serial": increment_batch_serial,
+	}

src/render/m2/m2_build_dispatch_planner.gd.uid

@@ -0,0 +1 @@
+uid://df0bv1x2x4j2x