HITL improvements

Author: christian-bromann

libs/langchain/src/agents/middlewareAgent/annotation.ts

@@ -37,7 +37,11 @@ export function createAgentAnnotationConditional<
       default: () => [],
     }),
     jumpTo: Annotation<"model_request" | "tools" | undefined>({
-      reducer: (x: any, y: any) => y ?? x,
+      /**
+       * Since `jumpTo` acts as a control command, we only want
+       * to apply it if explicitly set.
+       */
+      reducer: (_x: any, y: any) => y,
       default: () => undefined,
     }),
   };