muse-shim

muse-shim is an unofficial local model-provider shim that lets Meta Muse Code use OpenAI-compatible Responses APIs (including OpenRouter), OpenAI Codex OAuth, and the official Claude Code CLI—without changing Muse itself.

It is a loopback protocol shim. Start it with Muse, then switch between Codex and Claude from Muse's built-in /model menu. Codex uses the native Responses API; Claude uses the installed official CLI's non-interactive claude -p mode by default. Direct Anthropic Messages/API-key mode remains available as an explicit option.

Python 3.10+, standard library only (no runtime pip dependencies).

Provider matrix

Mode	Auth	Upstream wire format	What the shim does
auto (default)	Codex OAuth + Claude Code login	Codex Responses + Claude CLI print mode	Advertises both catalogs to Muse; routes each request from the /model selection
generic / http	API key (MUSE_SHIM_API_KEY or Muse’s bearer)	OpenAI Responses (POST …/responses)	Flattens Muse namespace tools; optional portable field stripping; streams JSON/SSE through
codex	Codex OAuth (CLI auth.json or env token)	Codex Responses backend	Loads/refreshes OAuth; preflights request; streams Responses events back to Muse
claude	Claude Code's existing login	Official claude -p structured output	Sends each turn on stdin and maps text/tool calls back to Responses for Muse

Default listen address: http://127.0.0.1:8787 (loopback only unless you explicitly opt out).

Prerequisites

• Python 3.10+
• Meta Muse Code CLI (muse) installed and runnable on your machine
• For generic mode: an upstream that implements OpenAI Responses (POST /responses with SSE/streaming and function tools as needed). Chat Completions-only servers need a separate adapter (e.g. LiteLLM) in front.
• For codex mode: Codex CLI logged in (codex login) so ~/.codex/auth.json (or CODEX_HOME) exists, or access/refresh tokens in the environment
• For claude mode: the official Claude Code CLI (claude) installed and logged in. Run claude login (or your normal Claude Code authentication flow) first.

Install

Clone and run from source (no install required):

git clone https://github.com/lu