Agent fails to run if serialized, restored, serialized again, and restored again

[shmuelk]

Describe the bug
A have a simplistic Agent, basically the example examples/agents/first.ts, changed to work with BAM and wrapped with a Web Server, written using Express. At the end of every interaction the agent is serialized and set into the user's session. When requests come in, if the session has a serialized agent in it, it is restored, otherwise the agent is created from scratch.

This works for two iterations. On the third one it fails, with an exception:

undefined:3
return (...args)=>target.invoke(...args)
                         ^

ReferenceError: target is not defined

To Reproduce

1. Add extra dependencies: yarn add express express-session @types/express @types/express-session
2. yarn start <code below>
3. In another terminal session:
   a. curl -X POST --data-binary '{"text": "Who is the president of the USA"}' -H "Content-Type: application/json" --cookie cookiefile --cookie-jar cookiefile http://localhost:3000
   b. curl -X POST --data-binary '{"text": "How old is he?"}' -H "Content-Type: application/json" --cookie cookiefile --cookie-jar cookiefile http://localhost:3000
   c. curl -X POST --data-binary '{"text": "Where was he born?"}' -H "Content-Type: application/json" --cookie cookiefile --cookie-jar cookiefile http://localhost:3000

Expected behavior
It should not fail.

Screenshots
Here is the terminal output of the server when it fails:

(node:52233) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.
(Use `node --trace-deprecation ...` to show where the warning was created)
[server]: Server is running at http://localhost:3000
Creating agent
Agent created
Running agent
Agent ran
Serializing agent
Agent serialized
Restoring agent from session
Agent restored from session
Running agent
Agent ran
Serializing agent
Agent serialized
Restoring agent from session
Agent restored from session
Running agent
undefined:3
return (...args)=>target.invoke(...args)
                         ^

ReferenceError: target is not defined
    at Object.eval [as callback] (eval at <anonymous> (file:///Users/kallner/Projects/ai-agents/bee-agent-framework/src/serializer/serializer.ts:1:11657), <anonymous>:3:26)
    at run (/Users/kallner/Projects/ai-agents/bee-agent-framework/src/emitter/emitter.ts:203:40)
    at _Emitter.invoke (/Users/kallner/Projects/ai-agents/bee-agent-framework/src/emitter/emitter.ts:204:60)
    at Object.on.toBoundedFunction.value (/Users/kallner/Projects/ai-agents/bee-agent-framework/src/emitter/emitter.ts:106:29)
    at run (/Users/kallner/Projects/ai-agents/bee-agent-framework/src/emitter/emitter.ts:203:40)
    at _Emitter.invoke (/Users/kallner/Projects/ai-agents/bee-agent-framework/src/emitter/emitter.ts:204:60)
    at Object.on.toBoundedFunction.value (/Users/kallner/Projects/ai-agents/bee-agent-framework/src/emitter/emitter.ts:106:29)
    at run (/Users/kallner/Projects/ai-agents/bee-agent-framework/src/emitter/emitter.ts:203:40)
    at _Emitter.invoke (/Users/kallner/Projects/ai-agents/bee-agent-framework/src/emitter/emitter.ts:204:60)
    at _Emitter.emit (/Users/kallner/Projects/ai-agents/bee-agent-framework/src/emitter/emitter.ts:189:23)

Code snippets

Here is the code being run above:

import "dotenv/config.js";
import express, {Express, Request, Response } from 'express';
import session from 'express-session';

import { BeeAgent } from "bee-agent-framework/agents/bee/agent";
import { BAMChatLLM } from "bee-agent-framework/adapters/bam/chat";
import { TokenMemory } from "bee-agent-framework/memory/tokenMemory";
import { DuckDuckGoSearchTool } from "bee-agent-framework/tools/search/duckDuckGoSearch";
import { OpenMeteoTool } from "bee-agent-framework/tools/weather/openMeteo";

const app: Express = express();
const port = process.env.PORT || 3000;

app.use(express.json());
app.use(session({
    secret: 'keyboard cat',
    resave: false,
    saveUninitialized: false
}));

declare module 'express-session' {
    interface SessionData {
        agent: string;
    }
}

app.post("/", async (req: Request, res: Response) => {
    var agent: BeeAgent;

    if (req.session && req.session.agent) {
        console.log("Restoring agent from session");
        agent = BeeAgent.fromSerialized(req.session.agent);
        console.log("Agent restored from session");
    } else {
        console.log("Creating agent");
        const llm = BAMChatLLM.fromPreset("meta-llama/llama-3-8b-instruct");
        agent = new BeeAgent({
            llm, // for more explore 'bee-agent-framework/adapters'
            memory: new TokenMemory({ llm }), // for more explore 'bee-agent-framework/memory'
            tools: [new DuckDuckGoSearchTool(), new OpenMeteoTool()], // for more explore 'bee-agent-framework/tools'
        });
        console.log("Agent created");
    }
    console.log("Running agent");
    const response = await agent.run(
        { prompt: req.body.text },
        {
          execution: {
            maxRetriesPerStep: 3,
            totalMaxRetries: 10,
            maxIterations: 20,
          },
        }
    );
    console.log("Agent ran");

    console.log("Serializing agent");
    req.session.agent = agent.serialize();
    console.log("Agent serialized");

    res.send(response.result.text);
});

app.listen(port, () => {
    console.log(`[server]: Server is running at http://localhost:${port}`);
});

Set-up:

• Bee version: [e.g. v0.0.29]
• Model provider [e.g. BAM]

[Tomas2D]

Good catch. Thanks for the report.

Fixed by 58d072f.

[shmuelk]

The fix works. Thanks.

[Tomas2D]

Great. Released in v0.0.30.