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Code Mode Example

This example shows how to use the @cloudflare/codemode ↗ library with the Agents SDK ↗ to build an agent where the LLM writes code to orchestrate tool calls, instead of calling them one at a time. This approach, called Code Mode ↗, reduces tokens spent by up to 80%, returns better results, and avoids bloating the context window.

This example shows you how to:

• Define tools as plain functions with Zod schemas
• Use createCodeTool to expose your tools to the LLM as a single "write code" tool
• Use DynamicWorkerExecutor to safely run LLM-generated code
• Wire it all together with AIChatAgent to handle chat over WebSockets

The agent uses three components from the @cloudflare/codemode ↗ library and the Agents SDK ↗:

• AIChatAgent (@cloudflare/ai-chat), your agent's base class. Handles chat over WebSockets, persists messages, and calls the LLM.
• createCodeTool (@cloudflare/codemode/ai), wraps your tools into a single codemode tool that accepts { code: string }.
• DynamicWorkerExecutor (@cloudflare/codemode), runs the LLM-generated code in an isolated Dynamic Worker.

The flow:

1. User sends a message over WebSocket.
2. AIChatAgent passes it to the LLM with a single tool available: codemode.
3. The LLM writes JavaScript, for example const projects = await codemode.listProjects(), instead of making individual tool calls.
4. DynamicWorkerExecutor spins up an isolated Worker and runs the code. Inside the sandbox, codemode.listProjects() calls your real listProjects implementation.
5. The result, any console output, and errors are returned to the LLM.
6. The LLM uses the result to respond to the user, or writes more code if it needs to.

DynamicWorkerExecutor is part of the @cloudflare/codemode library. When the LLM writes code that orchestrates your tools, that code needs to run somewhere safe. DynamicWorkerExecutor spins up an isolated Dynamic Worker for each execution using the Worker Loader binding. Inside the sandbox:

• A codemode proxy object routes calls like codemode.createTask(...) back to your real tool implementations over Workers RPC
• Setting globalOutbound to null blocks fetch(), so the code can only reach the outside world through your tools
• console.log output is captured and returned alongside the result
• Each execution gets its own Worker instance with a 30-second timeout

import { DynamicWorkerExecutor } from "@cloudflare/codemode";

const executor = new DynamicWorkerExecutor({
	loader: env.LOADER, // WorkerLoader binding from wrangler.jsonc
	timeout: 30000, // default: 30s
	globalOutbound: null, // null = fetch blocked
});

import { DynamicWorkerExecutor } from "@cloudflare/codemode";

const executor = new DynamicWorkerExecutor({
	loader: env.LOADER, // WorkerLoader binding from wrangler.jsonc
	timeout: 30000, // default: 30s
	globalOutbound: null, // null = fetch blocked
});

createCodeTool is part of @cloudflare/codemode. It takes your tools and an executor, and returns a single AI SDK tool(). It:

• Generates TypeScript type declarations from your tools' Zod schemas, so the LLM knows what is available and what the argument shapes look like.
• Puts those types in the tool's description, so the LLM sees a single tool with parameter { code: string } and a description that includes the full typed API surface.
• On execution, normalizes the LLM's code (strips markdown fences, wraps bare statements in async functions, auto-returns the last expression), then passes it to the executor.

import { createCodeTool } from "@cloudflare/codemode/ai";

const codemode = createCodeTool({
	tools: myTools, // Record<string, tool()> with Zod schemas
	executor, // DynamicWorkerExecutor
});

// The LLM sees: one tool called "codemode" with input { code: string }
// The description includes TypeScript types for all your tools

import { createCodeTool } from "@cloudflare/codemode/ai";

const codemode = createCodeTool({
	tools: myTools, // Record<string, tool()> with Zod schemas
	executor, // DynamicWorkerExecutor
});

// The LLM sees: one tool called "codemode" with input { code: string }
// The description includes TypeScript types for all your tools

The LLM writes an async arrow function. createCodeTool normalizes it and hands it to the executor. The executor builds a Worker module with a codemode proxy, runs the code, and returns { code, result, logs }.