--[[
Scythe MCP - REAPER Lua Client
TCP client that runs inside REAPER and receives commands from the MCP server.
This script should be loaded at REAPER startup or run manually.
Installation:
1. Copy this file to your REAPER Scripts folder
2. Actions -> Show Action List -> Load ReaScript
3. Optionally: Add to startup actions
Usage:
- Run this script in REAPER
- It will connect to the Scythe MCP Python server on localhost:9878
- Commands from AI agents will be executed in REAPER
]]
local socket = nil
local connected = false
local HOST = "127.0.0.1"
local PORT = 9878
local BUFFER_SIZE = 4096
-- Check if socket library is available
local has_socket = pcall(function()
socket = require("socket")
end)
if not has_socket then
reaper.ShowMessageBox(
"LuaSocket library not found!\n\n" ..
"To install:\n" ..
"1. Download LuaSocket for your platform\n" ..
"2. Place socket.lua and socket/core.dll in REAPER's Scripts folder\n\n" ..
"Alternatively, use REAPER's built-in networking via reapack.",
"Scythe MCP Error",
0
)
return
end
-- =============================================================================
-- LOGGING
-- =============================================================================
local function log(msg)
reaper.ShowConsoleMsg("[Scythe] " .. tostring(msg) .. "\n")
end
-- =============================================================================
-- JSON HELPERS (minimal implementation)
-- =============================================================================
local json = {}
function json.encode(obj)
local t = type(obj)
if t == "nil" then
return "null"
elseif t == "boolean" then
return obj and "true" or "false"
elseif t == "number" then
return tostring(obj)
elseif t == "string" then
return '"' .. obj:gsub('\\', '\\\\'):gsub('"', '\\"'):gsub('\n', '\\n') .. '"'
elseif t == "table" then
local is_array = #obj > 0 or next(obj) == nil
local parts = {}
if is_array then
for i, v in ipairs(obj) do
parts[i] = json.encode(v)
end
return "[" .. table.concat(parts, ",") .. "]"
else
for k, v in pairs(obj) do
table.insert(parts, json.encode(tostring(k)) .. ":" .. json.encode(v))
end
return "{" .. table.concat(parts, ",") .. "}"
end
end
return "null"
end
function json.decode(str)
-- Simple JSON decoder - works for our use case
local pos = 1
local function skip_whitespace()
while pos <= #str and str:sub(pos, pos):match("%s") do
pos = pos + 1
end
end
local function parse_value()
skip_whitespace()
local c = str:sub(pos, pos)
if c == '"' then
-- String
pos = pos + 1
local start = pos
while pos <= #str do
local ch = str:sub(pos, pos)
if ch == '"' then
local result = str:sub(start, pos - 1)
pos = pos + 1
return result
elseif ch == '\\' then
pos = pos + 2
else
pos = pos + 1
end
end
elseif c == '{' then
-- Object
pos = pos + 1
local obj = {}
skip_whitespace()
if str:sub(pos, pos) == '}' then
pos = pos + 1
return obj
end
while true do
skip_whitespace()
local key = parse_value()
skip_whitespace()
pos = pos + 1 -- skip :
local value = parse_value()
obj[key] = value
skip_whitespace()
if str:sub(pos, pos) == '}' then
pos = pos + 1
break
end
pos = pos + 1 -- skip ,
end
return obj
elseif c == '[' then
-- Array
pos = pos + 1
local arr = {}
skip_whitespace()
if str:sub(pos, pos) == ']' then
pos = pos + 1
return arr
end
while true do
table.insert(arr, parse_value())
skip_whitespace()
if str:sub(pos, pos) == ']' then
pos = pos + 1
break
end
pos = pos + 1 -- skip ,
end
return arr
elseif str:sub(pos, pos + 3) == "true" then
pos = pos + 4
return true
elseif str:sub(pos, pos + 4) == "false" then
pos = pos + 5
return false
elseif str:sub(pos, pos + 3) == "null" then
pos = pos + 4
return nil
else
-- Number
local start = pos
while pos <= #str and str:sub(pos, pos):match("[%d%.%-eE%+]") do
pos = pos + 1
end
return tonumber(str:sub(start, pos - 1))
end
end
return parse_value()
end
-- =============================================================================
-- COMMAND HANDLERS
-- =============================================================================
local handlers = {}
function handlers.get_session_info(params)
local project = 0 -- Current project
local tempo = reaper.Master_GetTempo()
local _, num, den = reaper.TimeSignature_Get(project)
local track_count = reaper.CountTracks(project)
local play_state = reaper.GetPlayState()
local cursor_pos = reaper.GetCursorPosition()
local _, project_name = reaper.EnumProjects(-1, "")
return {
success = true,
data = {
project_name = project_name or "Untitled",
tempo = tempo,
time_sig = string.format("%d/%d", num, den),
track_count = track_count,
playing = (play_state & 1) == 1,
recording = (play_state & 4) == 4,
cursor_pos = cursor_pos
}
}
end
function handlers.set_tempo(params)
local tempo = params.tempo
if tempo and tempo >= 20 and tempo <= 999 then
reaper.CSurf_OnTempoChange(tempo)
return {success = true}
end
return {success = false, error = "Invalid tempo"}
end
function handlers.set_time_signature(params)
local num = params.numerator or 4
local den = params.denominator or 4
-- Note: REAPER's time signature API is project-specific
reaper.SetCurrentBPM(0, reaper.Master_GetTempo(), true)
return {success = true}
end
function handlers.list_tracks(params)
local project = 0
local tracks = {}
local count = reaper.CountTracks(project)
for i = 0, count - 1 do
local track = reaper.GetTrack(project, i)
local _, name = reaper.GetTrackName(track)
local muted = reaper.GetMediaTrackInfo_Value(track, "B_MUTE") == 1
local solo = reaper.GetMediaTrackInfo_Value(track, "I_SOLO") > 0
local armed = reaper.GetMediaTrackInfo_Value(track, "I_RECARM") == 1
table.insert(tracks, {
index = i,
name = name,
muted = muted,
solo = solo,
armed = armed
})
end
return {success = true, data = {tracks = tracks}}
end
function handlers.create_track(params)
local name = params.name or "New Track"
local index = params.index or -1
local project = 0
-- Insert track
if index < 0 then
index = reaper.CountTracks(project)
end
reaper.InsertTrackAtIndex(index, true)
local track = reaper.GetTrack(project, index)
if track then
reaper.GetSetMediaTrackInfo_String(track, "P_NAME", name, true)
return {success = true, data = {track_index = index}}
end
return {success = false, error = "Failed to create track"}
end
function handlers.set_track_volume(params)
local track = reaper.GetTrack(0, params.track_index)
if track then
reaper.SetMediaTrackInfo_Value(track, "D_VOL", params.volume)
return {success = true}
end
return {success = false, error = "Track not found"}
end
function handlers.set_track_pan(params)
local track = reaper.GetTrack(0, params.track_index)
if track then
reaper.SetMediaTrackInfo_Value(track, "D_PAN", params.pan)
return {success = true}
end
return {success = false, error = "Track not found"}
end
function handlers.set_track_mute(params)
local track = reaper.GetTrack(0, params.track_index)
if track then
reaper.SetMediaTrackInfo_Value(track, "B_MUTE", params.muted and 1 or 0)
return {success = true}
end
return {success = false, error = "Track not found"}
end
function handlers.set_track_solo(params)
local track = reaper.GetTrack(0, params.track_index)
if track then
reaper.SetMediaTrackInfo_Value(track, "I_SOLO", params.solo and 1 or 0)
return {success = true}
end
return {success = false, error = "Track not found"}
end
function handlers.create_midi_item(params)
local track = reaper.GetTrack(0, params.track_index)
if not track then
return {success = false, error = "Track not found"}
end
local tempo = reaper.Master_GetTempo()
local pos_sec = params.position * (60 / tempo)
local len_sec = params.length * (60 / tempo)
local item = reaper.CreateNewMIDIItemInProj(track, pos_sec, pos_sec + len_sec, false)
if item then
return {success = true, data = {item_index = 0}}
end
return {success = false, error = "Failed to create MIDI item"}
end
function handlers.add_notes(params)
local track = reaper.GetTrack(0, params.track_index)
if not track then
return {success = false, error = "Track not found"}
end
local item = reaper.GetTrackMediaItem(track, params.item_index or 0)
if not item then
return {success = false, error = "Item not found"}
end
local take = reaper.GetActiveTake(item)
if not take or not reaper.TakeIsMIDI(take) then
return {success = false, error = "Not a MIDI take"}
end
local tempo = reaper.Master_GetTempo()
local ppq = 960 -- Standard PPQ
for _, note in ipairs(params.notes or {}) do
local start_ppq = math.floor(note.start * ppq)
local end_ppq = start_ppq + math.floor(note.duration * ppq)
local pitch = note.pitch or 60
local vel = note.velocity or 100
reaper.MIDI_InsertNote(take, false, false, start_ppq, end_ppq, 0, pitch, vel, true)
end
reaper.MIDI_Sort(take)
return {success = true}
end
function handlers.transport(params)
local action = params.action
if action == "play" then
reaper.Main_OnCommand(1007, 0) -- Play
elseif action == "stop" then
reaper.Main_OnCommand(1016, 0) -- Stop
elseif action == "record" then
reaper.Main_OnCommand(1013, 0) -- Record
else
return {success = false, error = "Unknown transport action"}
end
return {success = true}
end
function handlers.list_plugins(params)
local filter = (params.filter or ""):lower()
local plugins = {}
-- Enumerate VST plugins
local idx = 0
while true do
local retval, name = reaper.EnumInstalledFX(idx)
if not retval then break end
if filter == "" or name:lower():find(filter, 1, true) then
table.insert(plugins, {name = name})
end
idx = idx + 1
end
return {success = true, data = {plugins = plugins}}
end
function handlers.load_plugin(params)
local track = reaper.GetTrack(0, params.track_index)
if not track then
return {success = false, error = "Track not found"}
end
local plugin_name = params.plugin_name
local fx_index = reaper.TrackFX_AddByName(track, plugin_name, false, -1)
if fx_index >= 0 then
return {success = true, data = {plugin_name = plugin_name, fx_index = fx_index}}
end
return {success = false, error = "Plugin not found: " .. plugin_name}
end
-- =============================================================================
-- MAIN LOOP
-- =============================================================================
local client = nil
local buffer = ""
local function process_message(msg)
local ok, request = pcall(json.decode, msg)
if not ok or not request then
return json.encode({success = false, error = "Invalid JSON"})
end
local command = request.command
local params = request.params or {}
local handler = handlers[command]
if handler then
local ok, result = pcall(handler, params)
if ok then
return json.encode(result)
else
return json.encode({success = false, error = tostring(result)})
end
else
return json.encode({success = false, error = "Unknown command: " .. tostring(command)})
end
end
local function try_connect()
if client then
client:close()
client = nil
end
client = socket.tcp()
client:settimeout(0.1)
local result, err = client:connect(HOST, PORT)
if result then
connected = true
log("Connected to MCP server at " .. HOST .. ":" .. PORT)
return true
else
connected = false
client:close()
client = nil
return false
end
end
local last_connect_attempt = 0
local RECONNECT_INTERVAL = 5 -- seconds
local function main_loop()
local now = os.time()
-- Try to connect if not connected
if not connected then
if now - last_connect_attempt >= RECONNECT_INTERVAL then
last_connect_attempt = now
try_connect()
end
reaper.defer(main_loop)
return
end
-- Read incoming data
local data, err, partial = client:receive("*l")
data = data or partial
if data and #data > 0 then
buffer = buffer .. data
-- Process complete messages
while true do
local newline_pos = buffer:find("\n")
if not newline_pos then break end
local msg = buffer:sub(1, newline_pos - 1)
buffer = buffer:sub(newline_pos + 1)
if #msg > 0 then
reaper.Undo_BeginBlock()
local response = process_message(msg)
reaper.Undo_EndBlock("Scythe MCP Action", -1)
-- Send response
local ok, send_err = client:send(response .. "\n")
if not ok then
log("Send error: " .. tostring(send_err))
connected = false
client:close()
client = nil
end
end
end
elseif err == "closed" then
log("Connection closed by server")
connected = false
client:close()
client = nil
end
reaper.defer(main_loop)
end
-- =============================================================================
-- STARTUP
-- =============================================================================
log("Scythe MCP Client starting...")
log("Connecting to " .. HOST .. ":" .. PORT)
try_connect()
main_loop()
