diff --git a/index.ts b/index.ts
index 03b78e5..f9eb8c2 100644
--- a/index.ts
+++ b/index.ts
@@ -1,10 +1,21 @@
-import Koa from 'koa';
+import Koa, {Context, Next} from 'koa';
 import Router from 'koa-router'
 import bodyParser from 'koa-bodyparser';
 import {ChatModelFactory, Model} from "./model";
 
 const app = new Koa();
 const router = new Router();
+const errorHandler = async (ctx: Context, next: Next) => {
+    try {
+        await next();
+    } catch (err:any) {
+        ctx.response.status = err.status || 500;
+        ctx.response.body = {
+            message: err.message,
+        };
+    }
+};
+app.use(errorHandler);
 app.use(bodyParser());
 const chatModel = new ChatModelFactory({proxy: process.env.https_proxy || process.env.http_proxy});
 
@@ -14,7 +25,7 @@ interface AskReq {
 }
 
 router.get('/ask', async (ctx) => {
-    const {prompt, model = Model.Forefront} = ctx.query as unknown as AskReq;
+    const {prompt, model = Model.Forefront, ...options} = ctx.query as unknown as AskReq;
     if (!prompt) {
         ctx.body = 'please input prompt';
         return;
@@ -24,12 +35,12 @@ router.get('/ask', async (ctx) => {
         ctx.body = 'Unsupported  model';
         return;
     }
-    const res = await chat.ask({prompt: prompt as string});
+    const res = await chat.ask({prompt: prompt as string, options});
     ctx.body = res.text;
 });
 
 router.get('/ask/stream', async (ctx) => {
-    const {prompt, model = Model.Forefront} = ctx.query as unknown as AskReq;
+    const {prompt, model = Model.Forefront, ...options} = ctx.query as unknown as AskReq;
     if (!prompt) {
         ctx.body = 'please input prompt';
         return;
@@ -44,12 +55,12 @@ router.get('/ask/stream', async (ctx) => {
         "Cache-Control": "no-cache",
         "Connection": "keep-alive",
     });
-    const res = await chat.askStream({prompt: prompt as string});
+    const res = await chat.askStream({prompt: prompt as string, options});
     ctx.body = res.text;
 })
 
 app.use(router.routes());
 
-app.listen(3000,()=>{
+app.listen(3000, () => {
     console.log("Now listening: 127.0.0.1:3000");
 });
diff --git a/model/base.ts b/model/base.ts
index db40a0f..276fbd9 100644
--- a/model/base.ts
+++ b/model/base.ts
@@ -16,21 +16,14 @@ export interface ResponseStream {
 
 export interface Request {
     prompt: string;
-    history?: HistoryItem[];
     options?: any;
 }
 
-export interface HistoryItem {
-    question?: string;
-    answer?: string;
-}
-
-
 export abstract class Chat {
-    protected proxy: string | undefined;
+    protected options: ChatOptions | undefined;
 
     protected constructor(options?: ChatOptions) {
-        this.proxy = options?.proxy;
+        this.options = options;
     }
 
     public abstract ask(req: Request): Promise<Response>
diff --git a/model/forefront/index.ts b/model/forefront/index.ts
index c3ec144..e5474a3 100644
--- a/model/forefront/index.ts
+++ b/model/forefront/index.ts
@@ -13,9 +13,11 @@ interface ForefrontRequest extends Request {
     options?: {
         chatId?: string;
         prompt?: string;
-        actionType?: string;
+        actionType?: Action;
         defaultPersona?: string;
-        model?: string;
+        gptmodel?: Model;
+        // if set true, auto sign up when gpt4 times use up
+        resignup?: boolean;
     }
 }
 
@@ -48,9 +50,15 @@ export enum Action {
     newGreeting = 'new:greeting',
 }
 
+export enum Model {
+    gpt4 = 'gpt-4',
+    gpt3_5 = 'gpt-3.5-turbo',
+}
+
 export class Forefront extends Chat {
     private client: AxiosInstance | undefined;
     private session: ForefrontSessionInfo | undefined;
+    private keepAliveInterval: NodeJS.Timer | undefined = undefined;
 
     constructor(options?: ChatOptions) {
         super(options);
@@ -87,7 +95,7 @@ export class Forefront extends Chat {
 
     }
 
-    public async askStream(req: Request): Promise<ResponseStream> {
+    public async askStream(req: ForefrontRequest): Promise<ResponseStream> {
         if (!this.client) {
             await this.initClient();
         }
@@ -96,9 +104,9 @@ export class Forefront extends Chat {
         }
         const {
             chatId = v4(),
-            actionType = 'new',
+            actionType = Action.new,
             defaultPersona = '607e41fe-95be-497e-8e97-010a59b2e2c0',
-            model = 'gpt-4',
+            gptmodel = Model.gpt4,
         } = req.options || {};
         const jsonData = {
             text: req.prompt,
@@ -106,7 +114,7 @@ export class Forefront extends Chat {
             parentId: chatId,
             workspaceId: chatId,
             messagePersona: defaultPersona,
-            model: model,
+            model: gptmodel,
         };
         const base64Data = Buffer.from(this.session.userID + defaultPersona + chatId).toString('base64');
         const encryptedSignature = encryptWithAes256Cbc(base64Data, this.session.sessionID);
@@ -115,11 +123,21 @@ export class Forefront extends Chat {
             const response = await this.client?.post(
                 'https://streaming.tenant-forefront-default.knative.chi.coreweave.com/chat', jsonData,
                 {
-                    responseType: 'stream', headers: {'x-signature': encryptedSignature}
+                    responseType: 'stream', headers: {
+                        'x-signature': encryptedSignature, 'authorization': 'Bearer ' + this.session.token,
+                    }
                 } as AxiosRequestConfig
             );
             return {text: response.data};
-        } catch (e) {// session will expire very fast, I cannot know what reason
+        } catch (e: any) {// session will expire very fast, I cannot know what reason
+            if (e.response.status === 401) {
+                if (req.options?.resignup) {
+                    this.client = undefined;
+                    // do not retry auto, avoid loss control
+                    throw new Error('retry again, will sign up again');
+                }
+                throw new Error('try change model to gpt-3.5-turbo or set resignup = true')
+            }
             throw e;
         }
     }
@@ -132,7 +150,6 @@ export class Forefront extends Chat {
                 'authority': 'chat-server.tenant-forefront-default.knative.chi.coreweave.com',
                 'accept': '*/*',
                 'accept-language': 'en,fr-FR;q=0.9,fr;q=0.8,es-ES;q=0.7,es;q=0.6,en-US;q=0.5,am;q=0.4,de;q=0.3',
-                'authorization': 'Bearer ' + hisSession.token,
                 'cache-control': 'no-cache',
                 'content-type': 'application/json',
                 'origin': 'https://chat.forefront.ai',
@@ -158,8 +175,8 @@ export class Forefront extends Chat {
             origin: 'https://accounts.forefront.ai',
             'user-agent': agent, // Replace with actual random user agent
         }
-        if (this.proxy) {
-            session.proxy = this.proxy;
+        if (this.options?.proxy) {
+            session.proxy = this.options.proxy;
         }
         const signEmailRes = await session.post('https://clerk.forefront.ai/v1/client/sign_ups?_clerk_js_version=4.38.4',
             {data: {'email_address': mailAddress}});
@@ -193,6 +210,16 @@ export class Forefront extends Chat {
         const token = (loginRes.data as any).response.sessions[0].last_active_token.jwt;
         const sessionID = (loginRes.data as any).response.sessions[0].id
         const userID = (loginRes.data as any).response.sessions[0].user.id
+        this.keepAliveInterval = setInterval(async () => {
+            try {
+                const keepAliveRes = await session.post(`https://clerk.forefront.ai/v1/client/sessions/${sessionID}/tokens?_clerk_js_version=4.39.0`);
+                if (this.session) {
+                    this.session.token = (keepAliveRes.data as any).jwt as string;
+                }
+            } catch (e) {
+                console.error(e);
+            }
+        }, 30 * 1000);
         return {token, agent, sessionID, userID};
     }
 }
diff --git a/model/you/index.ts b/model/you/index.ts
index ceb3407..2c58e50 100644
--- a/model/you/index.ts
+++ b/model/you/index.ts
@@ -69,8 +69,8 @@ export class You extends Chat {
         super(props);
         this.session = new tlsClient.Session({clientIdentifier: 'chrome_108'});
         this.session.headers = this.getHeaders();
-        if (this.proxy) {
-            this.session.proxy = this.proxy;
+        if (this.options?.proxy) {
+            this.session.proxy = this.options.proxy;
         }
     }