Durable Object Facets

import { DurableObject } from "cloudflare:workers";

// In production, this code would come from an AI agent, a database,
// or user input — not a static string.
const AGENT_CODE = `
  import { DurableObject } from "cloudflare:workers";

  export class App extends DurableObject {
    fetch(request) {
      // Note: storage.kv provides simple KV storage backed by SQLite,
			// but you can also use SQL directly via storage.sql. See:
			// https://developers.cloudflare.com/durable-objects/api/sqlite-storage-api/

			let counter = this.ctx.storage.kv.get("counter") || 0;
      ++counter;
      this.ctx.storage.kv.put("counter", counter);

      return new Response("You have made " + counter + " requests.\\n");
    }
  }
`;

// AppRunner is your supervisor. Each instance manages one
// dynamically-loaded application.
export class AppRunner extends DurableObject {
	async fetch(request) {
		// Get a stub pointing to the "app" facet. If the facet has not
		// started yet (or has hibernated), the callback runs to tell the
		// runtime what code to load.
		const facet = this.ctx.facets.get("app", async () => {
			const worker = this.#loadDynamicWorker();

			// Extract the Durable Object class named "App" from the
			// dynamic Worker's exports.
			const appClass = worker.getDurableObjectClass("App");

			return { class: appClass };
		});

		// Forward the request to the facet.
		// You can also call RPC methods on the stub.
		return await facet.fetch(request);
	}

	#loadDynamicWorker() {
		// Use get() so the Worker stays warm across requests.
		// Each unique code version needs a unique ID.
		const codeId = "agent-code-v1";

		return this.env.LOADER.get(codeId, async () => {
			return {
				compatibilityDate: "2026-04-01",
				mainModule: "worker.js",
				modules: { "worker.js": AGENT_CODE },
				globalOutbound: null, // block network access
			};
		});
	}
}

export default {
	async fetch(request, env, ctx) {
		// Look up the AppRunner instance named "my-app".
		const obj = ctx.exports.AppRunner.getByName("my-app");

		// Forward the request to it.
		return await obj.fetch(request);
	},
};

import { DurableObject } from "cloudflare:workers";

// In production, this code would come from an AI agent, a database,
// or user input — not a static string.
const AGENT_CODE = `
  import { DurableObject } from "cloudflare:workers";

  export class App extends DurableObject {
    fetch(request) {
      // Note: storage.kv provides simple KV storage backed by SQLite,
			// but you can also use SQL directly via storage.sql. See:
			// https://developers.cloudflare.com/durable-objects/api/sqlite-storage-api/

			let counter = this.ctx.storage.kv.get("counter") || 0;
      ++counter;
      this.ctx.storage.kv.put("counter", counter);

      return new Response("You have made " + counter + " requests.\\n");
    }
  }
`;

// AppRunner is your supervisor. Each instance manages one
// dynamically-loaded application.
export class AppRunner extends DurableObject<Env> {
	async fetch(request: Request): Promise<Response> {
		// Get a stub pointing to the "app" facet. If the facet has not
		// started yet (or has hibernated), the callback runs to tell the
		// runtime what code to load.
		const facet = this.ctx.facets.get("app", async () => {
			const worker = this.#loadDynamicWorker();

			// Extract the Durable Object class named "App" from the
			// dynamic Worker's exports.
			const appClass = worker.getDurableObjectClass("App");

			return { class: appClass };
		});

		// Forward the request to the facet.
		// You can also call RPC methods on the stub.
		return await facet.fetch(request);
	}

	#loadDynamicWorker() {
		// Use get() so the Worker stays warm across requests.
		// Each unique code version needs a unique ID.
		const codeId = "agent-code-v1";

		return this.env.LOADER.get(codeId, async () => {
			return {
				compatibilityDate: "2026-04-01",
				mainModule: "worker.js",
				modules: { "worker.js": AGENT_CODE },
				globalOutbound: null, // block network access
			};
		});
	}
}

export default {
	async fetch(
		request: Request,
		env: Env,
		ctx: ExecutionContext,
	): Promise<Response> {
		// Look up the AppRunner instance named "my-app".
		const obj = ctx.exports.AppRunner.getByName("my-app");

		// Forward the request to it.
		return await obj.fetch(request);
	},
};