@agentcompose/sdk

TypeScript SDK for AgentCompose — define configurable agent components once, and run them in-process, as a local subprocess, or (soon) over HTTP.

Version: 0.1.0 · License: Apache-2.0 · Requires: Node ≥ 18.19

This SDK is the first runnable implementation of the AgentCompose contract. It covers the single-agent core: configuration, the task lifecycle, and the in-process + stdio transports. Composition (typed capability I/O, sessions) is deferred to a later release, in step with the spec.

📋 What works today. See STATUS.md for the exact feature matrix, the known gaps (HTTP transport, auth enforcement, typed capability I/O), and readiness by use case before you build on it.

💡 Writing an agent? Read the spec's Authoring Agents — Design Guidance first — agents are best built as thin adapters over existing tools, at the right level of abstraction.

Install

npm install @agentcompose/sdk

The published package ships compiled JavaScript + type declarations (dist/), so it runs on Node ≥ 18.19 with no build step on your side. (This repo is authored in strip-mode TypeScript; npm run build emits the dist/ that gets published.)

Define an agent (a reusable, configurable component)

import { defineAgent } from "@agentcompose/sdk";

export const research = defineAgent({
  descriptor: {
    agentcomposeVersion: "0.1.0",
    id: "dev.example.research",
    name: "Research Agent",
    version: "1.0.0",
    capabilities: [{ id: "research", description: "Summarize a topic." }],
    // Declared, typed configuration surface — run on defaults or override.
    configSchema: {
      type: "object",
      additionalProperties: false,
      properties: { depth: { type: "string", enum: ["shallow", "deep"], default: "shallow" } },
    },
  },
  async handle(goal, ctx) {
    ctx.progress(10, "working");
    ctx.message({ kind: "text", text: "…" });        // stream tokens
    return [{ kind: "text", text: `(${ctx.config.depth}) done` }];
  },
});

Run it three ways — same client interface

import { inProcess, serveStdio, spawnStdio } from "@agentcompose/sdk";

// 1. In-process (zero wire) — add the agent as a dependency.
const client = inProcess(research);

// 2. Host it as a stdio process:  node my-agent.ts
serveStdio(research);

// 3. Drive a subprocess agent from an orchestrator:
const client2 = spawnStdio("node", { args: ["./my-agent.ts"] });

await client.configure({ depth: "deep" });
const task = await client.submit([{ kind: "text", text: "agent standards" }]);
for await (const ev of client.events(task.id)) {
  if (ev.type === "message" && ev.delta.kind === "text") process.stdout.write(ev.delta.text);
}

Try the demos

npm run demo "AI agent interoperability"   # full driver: progress, streaming, artifact
npm run demo "?"                            # vague topic → input-required clarification loop
npm run demo:advanced                        # errors, cancellation, idempotency

The orchestrator spawns the reference agent as a subprocess, configures it, submits a goal, and reacts to every event type over stdio.

Lifecycle, events & errors

An agent is a task protocol, not a single request/response. Each task moves through a state machine and emits a typed event stream.

Task states: submitted → working → (input-required ⇄ working) → completed | failed | canceled

Event stream (for await (const ev of client.events(taskId))):

ev.type	Meaning	Builder emits via
status	state changed	automatic / ctx.status()
progress	percent + message	ctx.progress(50, "writing")
message	streamed output delta	ctx.message({ kind, text })
artifact	produced file/data	ctx.artifact(parts, name)
result	final payload	return [...]
error	structured failure	throw new AgentError(code, msg)

Errors carry a reserved code (ErrorCodes): TaskNotFound (-32000), CapabilityNotSupported (-32001), InvalidGoal (-32002), AuthRequired (-32003), RateLimited (-32004), InvalidState (-32005), UnsupportedVersion (-32006), InvalidConfiguration (-32007). Synchronous calls (e.g. configure) reject with an AgentError; task failures surface as an error event and a failed state.

Operational verbs: client.cancel(id) (aborts ctx.signal), requestInput() ⇄ provideInput() (pause/resume), and submit(goal, { idempotencyKey }) (dedupe retries).

API surface

Export	Purpose
defineAgent(def)	Declare an agent component (descriptor + handler).
inProcess(def)	Client backed by a direct, in-process runtime.
serveStdio(def)	Serve an agent over the stdio binding (NDJSON).
spawnStdio(cmd, opts)	Host-side client that spawns + drives a subprocess agent.
validateWireParams(name, params)	Validate inbound JSON-RPC params against the canonical @agentcompose/spec schemas (used at the stdio boundary; reusable for other transports).
AgentRuntime	The transport-neutral core (advanced use).

AgentClient (uniform across transports): describe, configure, submit, get, cancel, provideInput, events, close.

The handler ctx provides: config (effective, secrets resolved from env), status / message / progress / artifact emitters, requestInput() for the input-required flow, signal for cancellation, and taskId.

Test

npm test        # in-process + end-to-end stdio
npm run typecheck

License

Apache-2.0