fix(agent): align investigation waits and interruption messages

Separate waiting-stage reports from final recovery closure and route resumed runs through the actual handling phase. Keep superseded runs distinct from expired leases and transport failures, with focused heartbeat response coverage.

src/routes/chatStreamRoute.ts

@@ -46,6 +46,7 @@ import {
   operationalTaskClient,
   releaseOperationalTaskCredential,
   createScadaPresentationContinuation,
+  taskRunInterruptionMessage,
 } from "../product/operational-task-client.js";
 import { type SessionTranscriptStore } from "../sessions/transcriptStore.js";
 import { type SessionUiStateStore } from "../sessions/uiStateStore.js";
@@ -840,7 +841,7 @@ export const registerChatStreamRoute = (
         } else if (taskLeaseFailure) {
           publish("error", {
             session_id: clientSessionId,
-            message: "工况任务租约已失效，本次执行已停止，等待任务重新领取。",
+            message: taskRunInterruptionMessage(taskLeaseFailure),
             detail: taskLeaseFailure.message,
           });
         } else if (streamResult.failed && sessionPurpose === "task_execution" && activeSessionRecord.taskId) {