Your first agent

Create the project

bunx ayjnt new counter-demo
cd counter-demo
bun install

You'll see a counter-demo/agents/chat/agent.ts that the minimal template created. Delete chat/ — we're going to write our own:

rm -rf agents/chat
mkdir -p agents/counter

Write the agent

Create agents/counter/agent.ts with this content:

import { Agent } from "agents";
import type { GeneratedEnv } from "@ayjnt/env";

type State = { count: number };

export default class CounterAgent extends Agent<GeneratedEnv, State> {
  override initialState: State = { count: 0 };

  override async onRequest(request: Request): Promise<Response> {
    if (request.method === "POST") {
      const { by } = (await request.json()) as { by?: number };
      const next = this.state.count + (by ?? 1);
      this.setState({ count: next });
      return Response.json({ count: next, instance: this.name });
    }
    return Response.json({ count: this.state.count, instance: this.name });
  }
}

Four things are worth naming:

1. extends Agent<GeneratedEnv, State> — the first type parameter is the worker's env (DO bindings + any KV/R2/vars you declare). GeneratedEnv is regenerated by ayjnt on every build and contains exactly the DO bindings for every agent in your tree. The second is your state shape.
2. override initialState — the value this.state starts at when a new DO instance boots for the first time. Required because the base class declares an initialState field.
3. override async onRequest — the HTTP entrypoint. Return a Response. Called per request; the DO is the same instance across calls.
4. this.setState — persists new state and broadcasts it to any connected WebSocket clients. Don't mutate this.state directly — it's the durable shape and ayjnt/Cloudflare both key behavior off setState being the only writer.

Run it

bun run dev
# ✓ ayjnt: 1 agent(s) → .ayjnt/dist/wrangler.jsonc
# ⎔ Listening on http://localhost:8787

In another terminal:

# Read — no POST body, count starts at 0
curl http://localhost:8787/counter/demo
# → {"count":0,"instance":"demo"}

# Increment by 1
curl -X POST http://localhost:8787/counter/demo \
  -H "content-type: application/json" -d '{}'
# → {"count":1,"instance":"demo"}

# Increment by 7
curl -X POST http://localhost:8787/counter/demo \
  -d '{"by":7}' -H "content-type: application/json"
# → {"count":8,"instance":"demo"}

# Different instance — isolated state
curl http://localhost:8787/counter/another
# → {"count":0,"instance":"another"}

Add a method callable from another agent

The real power of agents shows up when they call each other. Add a reset method to the class:

export default class CounterAgent extends Agent<GeneratedEnv, State> {
  override initialState: State = { count: 0 };

  /** Public method — callable across the DO boundary via getAgent<T>. */
  async reset(): Promise<void> {
    this.setState({ count: 0 });
  }

  override async onRequest(request: Request): Promise<Response> {
    if (request.method === "DELETE") {
      await this.reset();
      return Response.json({ ok: true });
    }
    // ...rest unchanged
  }
}

Wrangler picks up the change via HMR, the DO reloads (in dev), and you can curl -X DELETE http://localhost:8787/counter/demo to reset. From inside another agent, (await getAgent<CounterAgent>(env.COUNTER_AGENT, "demo")).reset() would invoke the same method over Workers RPC with full type inference.

Deploy

Commit what you have, then:

git add -A && git commit -m "first counter agent"
git push
bun run deploy

ayjnt checks that your tree is clean and in sync with origin, writes the pending migration into .ayjnt/migrations.json, and then hands off to wrangler deploy. The first deploy will prompt you to wrangler login.

What you just did

• Created one Durable Object class (CounterAgent), bound at /counter/:instance.
• Registered it as a DO binding in the generated wrangler.jsonc, with an automatic migration entry in the lockfile.
• Exercised state persistence — each /counter/<x> is a separate DO.
• Added a public method that's both HTTP-accessible via onRequest and RPC-accessible via getAgent.
• Deployed it to production behind a git-safety check.

Next: Project anatomy walks you through the .ayjnt/ directory so you know which files you own and which the framework regenerates.