Hello World: a durable notebook

The smallest useful Agent Application can return to work it saved during an earlier run. A one-shot task runner cannot. This example is a notebook agent for one user. It saves notes in its workspace and maintains a short briefing that the user can open without reading through the conversation.

durable-notebook/
|-- instructions.md
|-- tools/
|   `-- save-note.ts
`-- agentapplication.yaml

The program

instructions.md contains the behavior written in natural language:

You maintain a research notebook for one user.

When the user asks you to remember something, append it to notes.md with the
date and source. When asked for a briefing, read notes.md and update briefing.md.
Never remove an earlier note unless the user asks you to.

save-note.ts provides the deterministic file operation:

import { appendFile } from "node:fs/promises";

export async function saveNote(text: string) {
  await appendFile("notes.md", `- ${new Date().toISOString()}: ${text}\n`);
  return { saved: "notes.md" };
}

The deployment declaration asks for a persistent workspace and uses the user ID as the instance key:

apiVersion: agentapplication.io/v0alpha1
kind: AgentApplication

metadata:
  name: durable-notebook

instance:
  key: user.id

workspace:
  durability: required
  isolation: per-instance

artifacts:
  - path: briefing.md

This is the portable contract proposed by the paper. A framework can express the same requirements in its own format.

Two runs, one continuing instance

On Monday, Ada says, “Remember that the launch moved to September 18.” The platform routes the request to Ada’s notebook instance. The agent writes the fact to notes.md, then the runtime suspends. On Friday, Ada asks for a launch briefing. The platform wakes the same instance and restores its workspace. The agent reads Monday’s note and writes briefing.md. Ada can open that file directly, share it, or return next week and ask the agent to revise it.

Defining property	Where it appears
Persistent agent instance	Ada’s stable instance key selects the same notebook on every run and keeps it separate from other users
Durable computational workspace	`notes.md`, `briefing.md`, and the agent’s instructions survive suspension
Durable work	The notes and briefing outlive the conversations that created them

Overview

Concepts

About the paper

Hello World Agent Application

Hello World: a durable notebook

The program

Two runs, one continuing instance

​Hello World: a durable notebook

​The program

​Two runs, one continuing instance

Hello World: a durable notebook

The program

Two runs, one continuing instance