---
title: "ACP HTTP Client"
description: "Protocol-pure ACP JSON-RPC over streamable HTTP client."
---

`acp-http-client` is a standalone, low-level package for ACP over HTTP (`/v2/rpc`).

Use it when you want strict ACP protocol behavior with no Sandbox-specific metadata or extension adaptation.

## Install

```bash
npm install acp-http-client
```

## Usage

```ts
import { AcpHttpClient } from "acp-http-client";

const client = new AcpHttpClient({
  baseUrl: "http://127.0.0.1:2468",
  token: process.env.SANDBOX_TOKEN,
});

await client.initialize({
  _meta: {
    "sandboxagent.dev": {
      agent: "mock",
    },
  },
});

const session = await client.newSession({
  cwd: "/",
  mcpServers: [],
  _meta: {
    "sandboxagent.dev": {
      agent: "mock",
    },
  },
});

const result = await client.prompt({
  sessionId: session.sessionId,
  prompt: [{ type: "text", text: "hello" }],
});

console.log(result.stopReason);
await client.disconnect();
```

## Scope

- Implements ACP HTTP transport and connection lifecycle.
- Supports ACP requests/notifications and session streaming.
- Does not inject `_meta["sandboxagent.dev"]`.
- Does not wrap `_sandboxagent/*` extension methods/events.

## Transport Contract

- `POST /v2/rpc` is JSON-only. Send `Content-Type: application/json` and `Accept: application/json`.
- `GET /v2/rpc` is SSE-only. Send `Accept: text/event-stream`.
- Keep one active SSE stream per ACP connection id.
- `x-acp-agent` is removed. Provide agent via `_meta["sandboxagent.dev"].agent` on `initialize` and `session/new`.

If you want Sandbox Agent metadata/extensions and higher-level helpers, use `sandbox-agent` and `SandboxAgentClient` instead.