(new): expand runtime APIs

(fix): harden concurrent lifecycle
(tests): add regression coverage
(doc): update v1.2 guidance

scene_locks.go

@@ -68,13 +68,3 @@ func uniqueSortedStrings(values []string) []string {
 	}
 	return result
 }
-
-func sceneKeysForContext(ctx *MessageContext) []string {
-	keys := make([]string, 0, 3)
-	for _, scope := range []SceneScope{SceneScopeUserChat, SceneScopeChat, SceneScopeUser} {
-		if key, ok := buildSceneKey(scope, ctx); ok {
-			keys = append(keys, key)
-		}
-	}
-	return keys
-}