/muse-delegation

name: muse-delegation
description: Delegates tasks to Meta's Muse Code CLI (muse) via delegation-core. Use when delegation-core selects Muse or repository-scale work needs a 1M-token context.
alwaysApply: false
category: delegation-implementation
tags:
- muse
- meta
- cli
- delegation
- large-context
dependencies:
- delegation-core
tools:
- muse
- delegation_executor.py
usage_patterns:
- muse-cli-integration
- repository-scale-analysis
- headless-ci-execution
complexity: intermediate
estimated_tokens: 600
references:
- delegation-core/shared-shell-execution.md

Muse Code Delegation

Overview

Muse Code is Meta's terminal coding agent, released August 2026 and built on Muse Spark 1.2. It runs either as an interactive TUI or as a one-shot headless command, and the headless form is what delegation uses.

The binary is `muse`. Meta publishes no npm or PyPI package for it: the documented install is a script served from Meta's own domain.

When To Use

• `delegation-core` selected `muse` for the task
• Repository-scale reading where Muse Spark 1.2's 1M-token context

helps

• Work that should run unattended, since `muse exec` is designed for

CI

When NOT To Use

• `META_API_KEY` is unset and the run cannot be interactive
• Structured output is required. No output-format flag is documented

for `exec`

Prerequisites

Installation

curl -fsSL https://dev.meta.ai/install.sh | sh

This pipes a remote script into a shell. Read <https://dev.meta.ai/docs/muse-code> before running it. The guided installer offers the same command and shows its source first:

make -C plugins/conjure delegate-setup

Authentication

Meta documents the environment variable as the CI path:

export META_API_KEY="<your-key>"
muse exec "Run the test suite and summarize failures."

A bare `muse` prompts for browser sign-in on first run, which is not usable unattended. There is no `muse auth status` command, so the service declares an empty auth probe and verification checks `META_API_KEY` instead.

Quick Start

Using the shared delegation executor

uv run python scripts/delegation_executor.py muse "Summarize this module" \
  --files src/

Through the Makefile

make -C plugins/conjure delegate-muse PROMPT='Explain this design'

Direct CLI usage

muse exec "Explain the retry logic in this package"

Smart Delegation

`muse` declares the strengths `code_execution` and `large_context`, and ranks behind gemini, qwen, minimax and glm in the candidate order. It declares `muse-spark-1.3` as its default and passes it with `--model`, because Muse Code's own default is `muse-spark-1.2` ([configuration](https://dev.meta.ai/docs/muse-code/configuration)). Meta recommends 1.3 for new work and gives it a 1,048,576-token context ([models](https://dev.meta.ai/docs/models)).

Muse-Specific Details

| Property | Value | |----------|-------| | Binary | `muse` | | Headless form | `muse exec <prompt>` | | Prompt delivery | positional, no flag | | Default model | `muse-spark-1.3` | | Version probe | `muse --version` | | Auth probe | none published | | Auth | `META_API_KEY` | | File context | inlined, no `@path` syntax |

The prompt is positional. A command ending in a flag would consume the prompt as that flag's value, which is why the service config sets `prompt_flag=None` and the War Room expert's command ends at `muse exec`.

Two claims circulating in third-party guides are not in Meta's own documentation and are not relied on here: a `--json` flag streaming JSONL events to stdout, and `muse auth set --api-key-stdin`. The confirmed JSONL reference is to on-disk session logs. Treat both as unverified until Meta documents them.

Exit Criteria

• [ ] `muse` resolves on PATH and `muse --version` answers
• [ ] `META_API_KEY` is set, or the operator accepted an interactive

sign-in

• [ ] The built command is `muse exec <prompt>` with the prompt as the

final argument and no prompt flag before it

• [ ] File context was inlined into the prompt rather than passed as

`@path` references

• [ ] Output saved to `delegations/muse/YYYYMMDD_HHMMSS.md`
• [ ] This skill ran because `delegation-core` selected `muse`, not by

default