import { getAgentByName, Agent } from "agents"; interface Env { PARENT: DurableObjectNamespace; } function json(data: unknown, init: ResponseInit = {}): Response { return new Response(JSON.stringify(data, null, 2), { ...init, headers: { "content-type": "application/json; charset=utf-8", ...init.headers } }); } function errorPayload(error: unknown): Record { return { name: error instanceof Error ? error.name : typeof error, message: error instanceof Error ? error.message : String(error), stack: error instanceof Error ? error.stack : undefined }; } function parentNameFrom(url: URL): string { return url.searchParams.get("parent") ?? "demo-parent"; } export class ParentAgent extends Agent { async onMessage( connection: { send(message: string): void }, message: string | ArrayBuffer ): Promise { const task = typeof message === "string" ? message : new TextDecoder().decode(message); connection.send( JSON.stringify({ ok: true, phase: "before-subAgent", parent: this.describe(), task }) ); const result = await this.spawnChild(task); connection.send( JSON.stringify({ ok: true, phase: "after-subAgent", result }) ); } async spawnChild(task = "spawn child"): Promise { const childName = `child-${crypto.randomUUID()}`; try { const child = await this.subAgent(ChildAgent, childName); const childResult = await child.ping(task); return { ok: true, parent: this.describe(), childName, child: childResult }; } catch (error) { return { ok: false, parent: this.describe(), childName, error: errorPayload(error) }; } finally { try { this.deleteSubAgent(ChildAgent, childName); } catch { // Best-effort cleanup only. } } } describe(): Record { return { className: this.constructor.name, name: this.name, idName: this.ctx.id.name, parentPath: this.parentPath, selfPath: this.selfPath }; } } export class ChildAgent extends Agent { async ping(task: string): Promise { await this.ctx.storage.put("lastPing", { task, at: Date.now() }); return { className: this.constructor.name, name: this.name, idName: this.ctx.id.name, parentPath: this.parentPath, selfPath: this.selfPath, lastPing: await this.ctx.storage.get("lastPing") }; } } export default { async fetch(request: Request, env: Env): Promise { const url = new URL(request.url); const parent = await getAgentByName(env.PARENT, parentNameFrom(url)); if (url.pathname === "/") { return json({ name: "cf-sub-agent-io-demo", description: "Minimal public repro for spawning an agents subAgent from a WebSocket message handler.", routes: { "GET /http-spawn": "Control path: calls parent.spawnChild() over RPC.", "WS /ws": "Repro path: send any message; onMessage calls parent.spawnChild()." } }); } if (url.pathname === "/http-spawn") { return json( await parent.spawnChild("spawned from HTTP/RPC control path") ); } if (url.pathname === "/ws") { return parent.fetch(request); } return json({ ok: false, error: "Not found" }, { status: 404 }); } } satisfies ExportedHandler;