HarnessesCoding agent

Muse Code

Meta's terminal and CI coding agent (the muse CLI), built for Muse Spark, with subagents in isolated worktrees and a replayable event log.

Maker
Meta
Kind
coding agent
Interface
CLI, SDK
Open source
—
GitHub stars
—
Models
Meta Muse models (default muse-spark-1.2; plans include Muse Spark, Muse Wonder, Muse Image)
Pricing
Pay-as-you-go per token with a Meta Model API key, or a flat monthly subscription (Everyday, High, Power and Maximum Usage plans). Plan prices aren't listed on the docs page. (source: official page, checked 2026-10-17)
MCP support
Yes
Subagents
Yes
Headless / scripted mode
Yes muse exec "<prompt>" (JSONL with --json).
Sandboxing
Yes OS sandbox on from the first run. MCP tools and hooks run outside it.
Note
Not the same as Meta's consumer personal agent 'Muse' (launched 2026-09-08), which isn't a developer harness. TypeScript SDK is in developer preview.
Official site
https://dev.meta.ai/docs/muse-code
Sources
dev.meta.ai/docs/muse-code · dev.meta.ai/docs/muse-code/extending · dev.meta.ai/docs/muse-code/subscriptions · dev.meta.ai/resources/blog/muse-code-new-plans-and-features · dev.meta.ai/resources/blog/build-with-muse-code · dev.meta.ai/docs/muse-code/permissions (docs checked 2026-10-17)
Other coding agents
Claude Code, OpenAI Codex CLI, Gemini CLI, OpenCode, goose, Aider, Cline, Roo Code, Kilo Code, OpenHands, Crush, Amp, Cursor CLI, Warp, Qwen Code, Plandex, Pi, Grok Build, Hermes Agent

Every value comes from the official site or docs, or from the GitHub API, on the date shown. A blank (—) means the value isn't stated or wasn't verified. It never means 'no'. Pricing is copied from official pages and changes often. No affiliate links.