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Run the Codex agent loop on Cloudflare Workers

WorkersAgents
View as MarkdownAgent setup

Run the Codex agent loop in a Cloudflare Durable Object with this experimental Agents SDK example ↗︎. Conversations, files, and completed model and tool results persist across restarts, allowing the agent to recover after interruptions.

The example adapts Codex’s Rust turn-processing code ↗︎ to WebAssembly and uses Agents SDK capabilities for storage and recovery.

The harness combines Agents SDK capabilities for durable execution:

  • Tasks journals model calls and tool execution. Completed steps reuse their recorded results after a restart. Interrupted steps can run again.
  • Sessions stores conversation history and compacts the model context.
  • Streams stores ordered events for replay after reconnecting.
  • Workspace provides tools to read and write persistent files.

For example, use OpenAI's GPT-6.1 Sol through AI Gateway. Configure the model with createAI and install the capabilities on a Durable Object:

import { DurableObject } from "cloudflare:workers";
import { Workspace } from "@cloudflare/computer";
import { Lifecycle } from "agents/lifecycle";
import { createAI } from "agents/models/ai-sdk";
import { Sessions } from "agents/sessions";
import { Streams } from "agents/streams";
import { Tasks } from "agents/tasks";
import { CodexHarness } from "./codex-harness";

export class Coder extends DurableObject {
	tasks = new Tasks();
	streams = new Streams();
	sessions = new Sessions();
	workspace = new Workspace({ storage: this.ctx.storage });

	codex = new CodexHarness({
		tasks: this.tasks,
		streams: this.streams,
		sessions: this.sessions,
		workspace: this.workspace,
		model: createAI({ binding: this.env.AI, id: "default" })(
			"openai/gpt-6.1-sol",
		),
	});

	lifecycle = Lifecycle.install(this)
		.use(this.tasks)
		.use(this.streams)
		.use(this.sessions)
		.use(this.codex);
}
import { DurableObject } from "cloudflare:workers";
import { Workspace } from "@cloudflare/computer";
import { Lifecycle } from "agents/lifecycle";
import { createAI } from "agents/models/ai-sdk";
import { Sessions } from "agents/sessions";
import { Streams } from "agents/streams";
import { Tasks } from "agents/tasks";
import { CodexHarness } from "./codex-harness";

export class Coder extends DurableObject<Env> {
	tasks = new Tasks();
	streams = new Streams();
	sessions = new Sessions();
	workspace = new Workspace({ storage: this.ctx.storage });

	codex = new CodexHarness({
		tasks: this.tasks,
		streams: this.streams,
		sessions: this.sessions,
		workspace: this.workspace,
		model: createAI({ binding: this.env.AI, id: "default" })("openai/gpt-6.1-sol"),
	});

	lifecycle = Lifecycle.install(this)
		.use(this.tasks)
		.use(this.streams)
		.use(this.sessions)
		.use(this.codex);
}

To use this model, configure the default gateway with Unified Billing or a stored OpenAI API key.

For setup, models, tools, and recovery behavior, refer to the Codex harness guide.