refactor: clarify thread execution failure notices

tests/single-thread-message-execution.test.ts

@@ -255,7 +255,7 @@ test("POST /api/v1/master-agent/tasks/[taskId]/complete blocks leaked thread env
   assert.equal(leakedReply, undefined);
 
   const opsNotice = updatedProject?.messages.find((message) =>
-    message.body.includes("线程返回了内部环境提示，已拦截"),
+    message.body.includes("线程环境异常，请重新绑定到正确项目或工作目录后再试。"),
   );
   assert.ok(opsNotice, "expected a user-facing system notice instead of raw environment diagnostics");
 });