render: extract static M2 build resource observer

src/tools/verify_m2_build_resource_snapshot.gd

@@ -8,6 +8,7 @@ const SNAPSHOT_SCRIPT := preload(
 )
 const SNAPSHOT_PATH := "res://src/render/m2/m2_build_resource_snapshot.gd"
 const DISPATCH_PATH := "res://src/render/m2/m2_build_dispatch_planner.gd"
+const STATIC_OBSERVER_PATH := "res://src/render/m2/m2_static_build_resource_observer.gd"
 const LOADER_PATH := "res://src/scenes/streaming/streaming_world_loader.gd"
 
 
@@ -134,10 +135,10 @@ func _verify_engine_lifetime(failures: Array[String]) -> void:
 func _verify_loader_and_dependency_boundaries(failures: Array[String]) -> void:
 	var loader_source := FileAccess.get_file_as_string(LOADER_PATH)
 	var dispatch_source := FileAccess.get_file_as_string(DISPATCH_PATH)
+	var static_observer_source := FileAccess.get_file_as_string(STATIC_OBSERVER_PATH)
 	var snapshot_source := FileAccess.get_file_as_string(SNAPSHOT_PATH)
 	for delegated_token in [
 		"M2_BUILD_RESOURCE_SNAPSHOT_SCRIPT.new(",
-		"\"adopt_static_observation\"",
 		"resource_snapshot.call(\"animated_prototype\")",
 		"resource_snapshot.call(\"static_mesh\")",
 	]:
@@ -146,6 +147,11 @@ func _verify_loader_and_dependency_boundaries(failures: Array[String]) -> void:
 			"loader uses %s" % delegated_token,
 			failures
 		)
+	_expect_true(
+		static_observer_source.contains("\"adopt_static_observation\""),
+		"static observer adopts snapshot",
+		failures
+	)
 	_expect_true(
 		dispatch_source.contains("resource_snapshot.call(\"animation_request_pending\")")
 		and dispatch_source.contains("resource_snapshot.call(\"has_static_mesh\")"),