feat(agent): improve investigation contracts and runtime readiness

src/routes/chatStream.ts

@@ -332,7 +332,7 @@ export const streamPromptResponse = async ({
         emittedText = true;
         done = true;
       }
-    } else await runtime.prompt(sessionId, message, toRuntimeModel(model));
+    } else await runtime.prompt(sessionId, message, toRuntimeModel(model), undefined, signal);
     onPromptDispatched?.();
   })
     .then(() => {
@@ -1048,7 +1048,7 @@ export const streamPromptResponse = async ({
           // the same managed session/lease, never create another task run.
           finalAnswer = undefined;
           sawResponseActivity = false;
-          await runtime.prompt(sessionId, typeof idleDecision === "string" ? idleDecision : "请处理收信箱中新到达的调查协作消息，按需回复，然后完成本轮工作。", toRuntimeModel(model));
+          await runtime.prompt(sessionId, typeof idleDecision === "string" ? idleDecision : "请处理收信箱中新到达的调查协作消息，按需回复，然后完成本轮工作。", toRuntimeModel(model), undefined, signal);
           continue;
         }
         if (waitForUserInput && await waitForUserInput()) {