muse-code-acp adapter for ACP editors

# muse-code-acp

Use [Muse Code](https://dev.meta.ai/docs/muse-code/) through an
[Agent Client Protocol (ACP)](https://agentclientprotocol.com) client, such as
Zed or VS Code with an ACP extension. Available features depend on the client.

> **Unofficial adapter.** Muse Code and Muse Spark are products of Meta
> Platforms, Inc. This community project is not affiliated with, endorsed by,
> or supported by Meta.

## Requirements and compatibility

- **Node.js 22+** for the npm installation.
- **Muse Code 1.1.1-R2514.1**, installed separately, with `muse serve`.
  This is the verified host for adapter **0.5.x**; the latest Muse installer
  may install a different version. Select the verified binary with
  `MUSE_CODE_EXECUTABLE`.
- Muse authentication through browser login or `META_API_KEY`.

**The supported baseline remains Muse 1.1.1-R2514.1.** Adapter **0.5.0** also
verifies SDK-created session load/resume, multi-stage allow/deny,
and HTTP MCP tool calls and startup failures on **1.2.1-R2847.1**. ACP-provided
MCP servers explicitly use required startup mode; authentication, malformed
responses and unreachable endpoints fail the prompt.

One host limitation remains on 1.2.1: legacy `muse exec` sessions saved with
`:auto-review` cannot be resumed in `muse serve`, whose automated reviewer is
unavailable. This affects the legacy-continuation portion of three live tests;
SDK-created session continuation passes. The adapter reports an actionable error
and does not replay the prompt or change the saved permission profile. Start a
new ACP session or continue the old one in Muse with reviewer support.

The launcher updates and removes superseded binaries, so pointing
`MUSE_CODE_EXECUTABLE` at an old launcher cache is not a durable pin. CI's public
1.1.1 artifacts remain downloadable; the exact macOS ARM64 and Linux download
URLs and SHA-256 checks are in [CI](.github/workflows/ci.yml). Keep the verified
binary at a separate path. These fixes are included in **0.5.0**.

The npm adapter and its pinned `@muse-code/sdk@0.1.1` dependency do not include
the Muse executable. Native execution, model access, persistence and sandboxing
remain owned by Muse.

## Quickstart

Install Node.js and the verified Muse host above, then replace the example path:

```sh
export MUSE_CODE_EXECUTABLE="/absolute/path/to/muse-1.1.1"
"$MUSE_CODE_EXECUTABLE" --version
"$MUSE_CODE_EXECUTABLE" ser