Flow Music (fmusic)

flowmusic-cli

Make music with Google Flow Music (Lyria) from your terminal, your scripts, or your AI agent.

fmusic is a command-line client and MCP server for flowmusic.app. You sign in once with your own Google account. After that it works without a browser: you describe a song, and a few minutes later you have a WAV file plus a JSON file with its details.

mcp-name: io.github.JvanLeeuwen4/flowmusic-cli

[!IMPORTANT]

Unofficial project. It is not affiliated with, endorsed by, or supported by Google. It uses the same endpoints as the flowmusic.app website, so it can break when the site changes. You use your own account and credits. Follow the Flow Music terms and the generative AI use policy, and don't use it for spam or mass generation.

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Quick start

uv tool install flowmusic-cli        # 1. install (or: pipx install flowmusic-cli)

fmusic auth login # 2. a browser opens once: sign in with Google fmusic generate "dreamy synthwave, airy female vocals, 100 bpm" # 3. make a song

Example output:

♪ take 1 (audio__create_song) Dreamy synthwave, airy female vocals, lush pads, 100 bpm

queued "Neon Drift" 3e2b2139-… (~35s) ✓ rendered "Neon Drift" ⬇ ~/Music/flowmusic-cli/2026-11-04/neon-drift_3e2b2139.wav Neon Drift 1:44 3e2b2139-2783-4171-a2b4-a51d03bc4504 continue with: fmusic chat 13001945-… "…"

What you need:

• Python 3.10+, via uv or pipx.
• Google Chrome or Edge, for the one-time sign-in.
• A Google account with Flow Music access. A Google AI subscription gives the most credits.

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What you can do

The full reference for every command and flag is in [docs/commands.md](docs/commands.md).

How generation works

Flow Music has an AI co-producer. Your prompt goes to it, and it decides what to make: often one or two *takes*. It rewrites your prompt into a detailed "sound prompt" and may suggest next steps. Each generation belongs to a conversation, and fmusic chat "…" continues that conversation, for example to tweak, extend or remix a take.

If you want exact control without the co-producer, use the experimental --direct mode. Your prompt goes to the song model as-is, and -n sets the number of takes:

fmusic generate "minimal techno, 126 bpm, hypnotic" --direct -n 2 --title "Night Drive"

Game music: seamless loops

Lyria songs have an intro and a real ending, so looping the raw file jumps from the final chord straight back to the start. --loop fixes that:

Listen to 16 seconds around the seam of a 1-minute Lyria jingle: 🔊 raw file, looped · 🔊 fmusic loop. The seam is at 0:08.

uv tool install --force "flowmusic-cli[game]"     # once: adds numpy + soundfile (no ffmpeg needed)

fmusic generate "cozy pixel-art village theme, acoustic guitar, 90 bpm" --instrumental --loop

⬇ ~/Music/flowmusic-cli/2026-11-05/peaceful-village_467c790b.wav

⟳ loop 0:24 → 1:44 (length 80.0s, similarity 0.96 good) ⬇ ~/Music/flowmusic-cli/2026-11-05/peaceful-village_467c790b_loop.ogg

• The prompt gets a short "loopable: steady groove, no intro, no ending" instruction.
• ` _loop.ogg` is cut and crossfaded so it loops cleanly when you turn looping on in any engine (Godot, Unity, web audio). Use --loop-format wav|both for WAV.
• The full WAV keeps its intro and gets the loop points as a smpl chunk. In Godot, import it with *Loop Mode: Detect From WAV* to play the intro once and then loop.
• The JSON gets loop: {start_s, end_s, length_s, start_sample, end_sample, similarity, quality}. When quality is poor, the seam may be audible; try the other take.
• Songs you already have don't cost credits: fmusic loop or fmusic loop theme.wav.

How the loop is found is described in docs/how-it-works.md.

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Install

The package installs two equivalent commands, fmusic and flowmusic.

Sign in

fmusic auth login      # opens Chrome/Edge: sign in with Google; the window closes by itself

fmusic auth status # shows email, subscription tier, credits (exit code 0 = OK) fmusic auth logout

• You sign in once. Tokens refresh automatically, so you won't need to sign in again unless you log out or the session is revoked.
• To use several accounts, add --profile work (or set FMUSIC_PROFILE=work) to any command.
• Can't open a browser (for example on a server)? Sign in on flowmusic.app on another machine. In the browser's DevTools, open the Network tab and copy the Cookie header of any __api request. Then run:

  fmusic auth import "sb-sb-auth-token.0=base64-…; sb-sb-auth-token.1=…"

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Use it from AI agents

fmusic is built to be driven by agents. There are three ways:

1. Claude Code plugin (skill + MCP server)

/plugin marketplace add JvanLeeuwen4/flowmusic-cli

/plugin install fmusic@flowmusic-cli

Then run fmusic auth login once in a terminal. The plugin starts the MCP server through uvx, so you don't need to install anything else.

2. Any MCP client (Claude Desktop, Cursor, VS Code, Codex, …)

Add this to the client's MCP configuration. It only needs uv:

{

"mcpServers": { "fmusic": { "command": "uvx", "args": ["--from", "flowmusic-cli[game]", "fmusic", "mcp", "run"] } } }

If fmusic is already installed, this command writes the config for you:

fmusic mcp setup --target claude-code      # or: claude-desktop, print

The tools and their parameters are listed in [docs/mcp.md](docs/mcp.md).

3. The CLI with --json

Every command accepts --json:

• Results go to stdout as one JSON object: {"status":"ok","data":…} or {"status":"fail","error":{…}}.
• Progress messages go to stderr.
• Exit codes are stable. See docs/troubleshooting.md.

fmusic --json generate "calm piano, 70 bpm" --instrumental | jq '.data.clips[].files'

Agents working *on* this repository should read AGENTS.md.

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Where files go

By default, songs are saved to ~/Music/flowmusic-cli/ /. Use -o DIR to choose a folder; the files then go directly in it. Each clip produces:

neon-drift_3e2b2139.wav     # audio (or .m4a with --format m4a; both with --format both)

neon-drift_3e2b2139.json # title, duration, sound prompt, lyrics, ids, URLs neon-drift_3e2b2139.jpg # cover art (only with --cover)

Configuration

All settings are optional environment variables.

Troubleshooting

The most common issues:

• Uploads with vocals fail with "not available in your region". In some regions, including the EU, Flow Music doesn't allow uploading tracks with vocals or removing vocals from them. Upload instrumentals instead.
• `Session expired` (exit code 3). Run fmusic auth login again.
• Google won't let you sign in. Make sure Chrome or Edge is installed. You can also use fmusic auth import instead.

Everything else is in [docs/troubleshooting.md](docs/troubleshooting.md).

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Documentation

Contributing

Issues and pull requests are welcome. See AGENTS.md for the layout and test commands:

uv run --extra dev pytest

The sign-in approach is inspired by gflow-cli. MIT licensed.