Reaper Daemon

Reaper Daemon

Reaper Daemon is a REAPER MCP server and file bridge for driving REAPER from an AI agent, including mixing your session with Claude or any other agent. No network socket, no port, no extensions.

The agent drops a JSON command file in a folder. A Lua script inside REAPER runs it and writes a JSON result back. That's the whole protocol. It works with Claude Code, Codex, Cursor, or anything else that can read and write files, and an optional stdio MCP server, reaper_mcp.py, exposes the same bridge as tools for Claude Desktop and any other MCP client.

macOS, Windows, Linux. Pure Lua inside REAPER, plain Python 3 outside, no pip packages for the core bridge and MCP server. Audio-to-drum MIDI transcription uses a separate optional model environment. Every change runs inside a REAPER undo block, so Ctrl+Z reverts anything an agent does.

Install

Reaper Daemon has two halves, a Lua bridge that runs inside REAPER and the tools that talk to it. Both come from a clone of this repository on the computer REAPER runs on, so install here first, even if you found it through the Claude plugin directory.

git clone https://github.com/wretcher207/reaper-daemon.git

cd reaper-daemon python3 setup/install.py

Restart REAPER, then check the bridge is alive:

python3 reaperd.py status

Rendering and audio capture are off until you allow them, and every measurement needs them, including verify_change. To do that, run:

python3 setup/install.py --allow-audio-writes

Saving the project, changing REAPER preferences and running Lua scripts have their own switches; see docs/install.md.

Prefer ReaPack, or want to load the bridge by hand? See docs/install.md.

Claude plugin

The repository is also a Claude plugin. It bundles the MCP server with five skills: setup, drum programming, drum humanizing, guitar and bass parts, and MIDI for an existing arrangement. The plugin drives the install above, so if you added it before installing, ask Claude to set up Reaper Daemon. The setup skill finds what's missing, runs the clone and installer with you, asks which disk writes to allow, and checks that REAPER answers.

When you add the plugin, Claude asks for two settings:

• Reaper Daemon folder: where you cloned it. Default ~/reaper-daemon.
• Python command: default python3. On Windows, use python or py if python3 isn't on your PATH.

Cowork doesn't ask, so it uses those defaults. To try the plugin in Claude Code straight from your clone:

claude --plugin-dir /path/to/reaper-daemon

The MCP server runs on your computer, next to REAPER. It works in Claude Code and in Cowork sessions on your machine. Chat on claude.ai loads the skills but can't reach REAPER.

Mix with an AI agent

Point Claude, or any agent talking to Reaper Daemon, at your open REAPER session and ask it to work on the mix. It reads every plugin and parameter with scan_fx, sets FX values in real units like "-2.5 dB", and writes automation. verify_change captures the track before and after a move and reports what changed in the audio, so you are not taking its word for it. Every move sits inside a REAPER undo block, and your ears make the call.

Example prompts:

• "The bass is muddy around 300 Hz, pull it down."
• "Bring the vocal down so it sits with the mix instead of on top."
• "Tune the bass until its LUFS is down 3 dB."
• "What plugins are on the drum bus, and what are they set to?"

See MCP server for setup and Verify for what the measurements do and do not prove.

What it does

The bridge knows nothing about any specific plugin or drum library. Agents discover what a project contains and act on it by name.

Three ways to talk to it

CLI. One Python entry point for everything an agent does.

python3 reaperd.py send commands/examples/get_context.json --wait

python3 reaperd.py shred --track argent-l --bars-file riff.txt --seed 101

MCP server. reaper_mcp.py wraps the bridge as tools over stdio. Ask Claude Desktop to "measure the drums" and it does.

Daemon Console. A chat panel docked inside REAPER, backed by a headless Claude Code session that always knows which track you have selected.

Docs

Agents should read AGENTS.md, CLAUDE.md, and bridge/command_schema.md. Two bundled skills, arrangement-midi and drum-humanize, cover MIDI composition and drum humanization. song-planner plans and drafts whole songs from a brief, a riff or a reference.

Security

Any process that can write to inbox/ can drive REAPER. Keep the bridge folder local and off shared drives. Details in docs/security.md.

What it runs and sends

Everything runs on your machine. The MCP server and CLI are plain Python with no network calls. The bridge is a Lua script inside REAPER. It trades JSON files with the server through the Reaper Daemon folder, which also holds logs and the MIDI files it generates. Renders and captures write audio files only if you turn on audio writes, which are off by default. Nothing leaves your computer.

Three optional pieces do more, and only if you install them:

• Drum transcription downloads its Python packages and model weights during setup, and Demucs downloads its weights on the first separation job. Audio stays local.
• analyze_track and compare_tracks run Post Mortem from your PATH.
• The Daemon Console starts a Claude Code session on your machine, which talks to Anthropic like any Claude Code session.

License

MIT. See LICENSE.

Keyboard performance setup, MIDI/controller tests and template saving are documented in the performance workflow.