Keep chat stream alive during long runs

frontend/app/app/api/chat/route.ts

@@ -13,6 +13,7 @@ import {
 } from "@/lib/claw-auth";
 
 export const runtime = "nodejs";
+export const maxDuration = 300;
 
 type ClawChatResponse = {
 	final_output?: string;
@@ -92,9 +93,19 @@ export async function POST(req: Request) {
 	const stream = createUIMessageStream({
 		execute: async ({ writer }) => {
 			const streamState = { textStarted: false, textStreamed: false };
+			let heartbeatCount = 0;
+			const heartbeat = setInterval(() => {
+				heartbeatCount += 1;
+				writer.write({
+					type: "reasoning-delta",
+					id: "reasoning-1",
+					delta: `\n仍在处理请求，已等待 ${formatDuration(heartbeatCount * 15000)}。`,
+				});
+			}, 15000);
 			writer.write({ type: "start" });
 			writer.write({ type: "start-step" });
 
+			try {
 				const startedAt = Date.now();
 				writer.write({ type: "reasoning-start", id: "reasoning-1" });
 				writer.write({
@@ -141,6 +152,9 @@ export async function POST(req: Request) {
 						usage: payload.usage,
 					},
 				});
+			} finally {
+				clearInterval(heartbeat);
+			}
 		},
 	});