// Copyright (c) 2026 Adin Kwok <adin@adin.dev>
import { readFileSync } from "node:fs";
import { Client, Server, type OSCArg } from "node-osc";
export type { OSCArg };
interface PendingQuery {
resolve: (args: OSCArg[]) => void;
reject: (err: Error) => void;
timer: ReturnType<typeof setTimeout>;
}
function getWSLHostIP(): string {
try {
const resolv = readFileSync("/etc/resolv.conf", "utf-8");
const match = resolv.match(/nameserver\s+(\S+)/);
if (match) return match[1];
} catch {
// Not running in WSL, fall through
}
return "127.0.0.1";
}
export class AbletonOSC {
private client: Client | null = null;
private server: Server | null = null;
private pending = new Map<string, PendingQuery>();
constructor(
private host = getWSLHostIP(),
private sendPort = 11000,
private receivePort = 11001,
private timeoutMs = 5000,
) {}
async connect(): Promise<void> {
this.client = new Client(this.host, this.sendPort);
await new Promise<void>((resolve, reject) => {
this.server = new Server(this.receivePort, "0.0.0.0", () => resolve());
this.server.on("error", reject);
});
this.server!.on("message", (msg: OSCArg[]) => {
const address = msg[0] as string;
const args = msg.slice(1) as OSCArg[];
const pending = this.pending.get(address);
if (pending) {
clearTimeout(pending.timer);
this.pending.delete(address);
pending.resolve(args);
}
});
// Verify AbletonOSC is reachable
try {
await this.query("/live/test");
console.error(`ableton-mcp: connected to AbletonOSC at ${this.host}:${this.sendPort}`);
} catch {
this.disconnect();
throw new Error(
`Could not reach AbletonOSC at ${this.host}:${this.sendPort}. ` +
"Is Ableton Live running with AbletonOSC enabled?",
);
}
}
disconnect(): void {
for (const [, pending] of this.pending) {
clearTimeout(pending.timer);
pending.reject(new Error("OSC client disconnected"));
}
this.pending.clear();
this.client?.close();
this.server?.close();
this.client = null;
this.server = null;
}
query(address: string, ...args: OSCArg[]): Promise<OSCArg[]> {
if (!this.client) throw new Error("OSC client not connected");
return new Promise((resolve, reject) => {
const timer = setTimeout(() => {
this.pending.delete(address);
reject(new Error(`OSC query timed out: ${address}`));
}, this.timeoutMs);
this.pending.set(address, { resolve, reject, timer });
this.client!.send(address, ...args);
});
}
send(address: string, ...args: OSCArg[]): void {
if (!this.client) throw new Error("OSC client not connected");
this.client.send(address, ...args);
}
}
