muse-openrouter-shim

Run Meta's muse coding CLI on any OpenRouter API key. No Meta account, no Meta Model API key, any model you want.

muse (unmodified) ──> local shim (port 8399) ──> openrouter.ai/api/v1/responses

Why

Muse Code ships with a single compiled provider that talks to api.meta.ai and only accepts a Meta Model API key. The multi-provider code (OpenRouter, OpenAI, Anthropic) exists in the binary but is feature-gated out of the public build.

It turns out the wire protocol is just the OpenAI Responses API plus one proprietary endpoint, GET /muse-code/models, that muse needs at startup. So a ~180 line local proxy is enough:

• serves a synthetic model catalog at /muse-code/models
• streams POST /responses through to OpenRouter untouched (auth passes through, muse never knows)
• maps muse's extended reasoning efforts (xhigh, ultra) down to high
• swallows telemetry so nothing else phones home

The catalog wire format was recovered by pointing --base-url at a local listener and iterating on the binary's serde decode errors until the schema parsed. Full field layout is documented in shim.py.

Setup

Requires Python 3 (stdlib only, no pip installs) and an installed muse (curl -fsSL https://dev.meta.ai/install.sh | bash).

git clone https://github.com/joymadhu49/muse-openrouter-shim
cd muse-openrouter-shim
cp .env.example .env
# paste your OpenRouter key into .env

Use

./muse-or                 # interactive TUI
./muse-or exec "fix the failing test"
./muse-or --model x-ai/grok-4.3

muse-or starts the shim automatically if it is not already running, injects the base URL and model, and hands your OpenRouter key to muse as META_API_KEY so the shim can pass it through as the Bearer token. Set a default model with MUSE_OR_MODEL in .env.

Model compatibility

Verified working end to end, including tool calls:

Model	Status
meta/muse-spark-1.2	works (Meta's own model, via OpenRouter billing)
openai/gpt-5.1	works (default)
x-ai/grok-4.3	works
google/gemini-2.5-pro	works
deepseek/deepseek-v3.2	works
qwen/qwen3-coder	works
anthropic/*	blocked: the provider returns a Terms of Service 403 for this scaffold
moonshotai/kimi-k2	fails: 131k context is smaller than muse's startup prompt

Anything on openrouter.ai/models with a