mcp-windows/src/shell.ts

#!/usr/bin/env node
/* Copyright (C) 2026 Moko Consulting <hello@mokoconsulting.tech>
 * SPDX-License-Identifier: GPL-3.0-or-later
 */

import { execFile, spawn, ChildProcess } from 'node:child_process';
import { promisify } from 'node:util';

const execFileAsync = promisify(execFile);

export interface ShellResult {
	stdout: string;
	stderr: string;
	exitCode: number;
}

const POWERSHELL = 'powershell.exe';
const DEFAULT_TIMEOUT = 30_000;

/**
 * Run a PowerShell command and return stdout/stderr/exitCode.
 * Commands are wrapped with -NoProfile -NonInteractive for speed and safety.
 */
export async function runPowerShell(
	command: string,
	options: { timeout?: number; cwd?: string } = {},
): Promise<ShellResult> {
	const timeout = options.timeout ?? DEFAULT_TIMEOUT;
	try {
		const { stdout, stderr } = await execFileAsync(POWERSHELL, [
			'-NoProfile',
			'-NonInteractive',
			'-Command',
			command,
		], {
			timeout,
			cwd: options.cwd,
			maxBuffer: 10 * 1024 * 1024,
			windowsHide: true,
		});
		return { stdout: stdout.trimEnd(), stderr: stderr.trimEnd(), exitCode: 0 };
	} catch (err: unknown) {
		const e = err as { stdout?: string; stderr?: string; code?: number | string; killed?: boolean };
		if (e.killed) {
			return {
				stdout: e.stdout?.trimEnd() ?? '',
				stderr: `Command timed out after ${timeout}ms`,
				exitCode: -1,
			};
		}
		return {
			stdout: e.stdout?.trimEnd() ?? '',
			stderr: e.stderr?.trimEnd() ?? String(err),
			exitCode: typeof e.code === 'number' ? e.code : 1,
		};
	}
}

/**
 * Run a PowerShell command that returns JSON. Wraps output with ConvertTo-Json
 * and parses the result.
 */
export async function runPowerShellJson<T = unknown>(
	command: string,
	options: { timeout?: number; cwd?: string } = {},
): Promise<T> {
	const wrapped = `${command} | ConvertTo-Json -Depth 10 -Compress`;
	const result = await runPowerShell(wrapped, options);
	if (result.exitCode !== 0) {
		throw new Error(result.stderr || `PowerShell exited with code ${result.exitCode}`);
	}
	if (!result.stdout) {
		return [] as unknown as T;
	}
	return JSON.parse(result.stdout) as T;
}

/**
 * Run a generic shell command (cmd, bash, pwsh).
 */
export async function runShell(
	command: string,
	options: {
		shell?: 'pwsh' | 'cmd' | 'bash';
		timeout?: number;
		cwd?: string;
	} = {},
): Promise<ShellResult> {
	const shell = options.shell ?? 'pwsh';
	const timeout = options.timeout ?? DEFAULT_TIMEOUT;

	let executable: string;
	let args: string[];

	switch (shell) {
		case 'cmd':
			executable = 'cmd.exe';
			args = ['/c', command];
			break;
		case 'bash':
			executable = 'bash';
			args = ['-c', command];
			break;
		case 'pwsh':
		default:
			executable = POWERSHELL;
			args = ['-NoProfile', '-NonInteractive', '-Command', command];
			break;
	}

	try {
		const { stdout, stderr } = await execFileAsync(executable, args, {
			timeout,
			cwd: options.cwd,
			maxBuffer: 10 * 1024 * 1024,
			windowsHide: true,
		});
		return { stdout: stdout.trimEnd(), stderr: stderr.trimEnd(), exitCode: 0 };
	} catch (err: unknown) {
		const e = err as { stdout?: string; stderr?: string; code?: number | string; killed?: boolean };
		if (e.killed) {
			return {
				stdout: e.stdout?.trimEnd() ?? '',
				stderr: `Command timed out after ${timeout}ms`,
				exitCode: -1,
			};
		}
		return {
			stdout: e.stdout?.trimEnd() ?? '',
			stderr: e.stderr?.trimEnd() ?? String(err),
			exitCode: typeof e.code === 'number' ? e.code : 1,
		};
	}
}


// ── Persistent Terminal Sessions ─────────────────────────────────────────

export interface TerminalSession {
	pid: number;
	shell: string;
	process: ChildProcess;
	output: string[];
	startedAt: Date;
}

const sessions = new Map<number, TerminalSession>();
const MAX_OUTPUT_LINES = 5000;

export function startSession(shell: 'pwsh' | 'cmd' | 'bash' | 'python' | 'node' | 'wsl' = 'pwsh'): TerminalSession {
	let executable: string;
	let args: string[];

	switch (shell) {
		case 'cmd':
			executable = 'cmd.exe';
			args = [];
			break;
		case 'bash':
			executable = 'bash';
			args = [];
			break;
		case 'python':
			executable = 'python';
			args = ['-i'];
			break;
		case 'node':
			executable = 'node';
			args = [];
			break;
		case 'wsl':
			executable = 'wsl.exe';
			args = [];
			break;
		case 'pwsh':
		default:
			executable = POWERSHELL;
			args = ['-NoProfile', '-NoLogo'];
			break;
	}

	const proc = spawn(executable, args, {
		stdio: ['pipe', 'pipe', 'pipe'],
		windowsHide: true,
		detached: false,
	});
	// Don't let terminal sessions prevent the MCP server from exiting
	proc.unref();
	(proc.stdout as any)?.unref?.();
	(proc.stderr as any)?.unref?.();
	(proc.stdin as any)?.unref?.();

	const session: TerminalSession = {
		pid: proc.pid!,
		shell,
		process: proc,
		output: [],
		startedAt: new Date(),
	};

	const pushLine = (line: string) => {
		session.output.push(line);
		if (session.output.length > MAX_OUTPUT_LINES) {
			session.output.splice(0, session.output.length - MAX_OUTPUT_LINES);
		}
	};

	proc.stdout?.on('data', (data: Buffer) => {
		data.toString().split('\n').forEach(pushLine);
	});
	proc.stderr?.on('data', (data: Buffer) => {
		data.toString().split('\n').forEach(l => pushLine(`[stderr] ${l}`));
	});
	proc.on('exit', () => {
		pushLine(`[session ended]`);
	});

	sessions.set(proc.pid!, session);
	return session;
}

export function sendToSession(pid: number, input: string): void {
	const session = sessions.get(pid);
	if (!session) throw new Error(`No session with PID ${pid}`);
	if (session.process.exitCode !== null) throw new Error(`Session ${pid} has ended`);
	session.process.stdin?.write(input + '\n');
}

export function readSessionOutput(pid: number, offset = 0, length?: number): string[] {
	const session = sessions.get(pid);
	if (!session) throw new Error(`No session with PID ${pid}`);
	const start = offset < 0 ? Math.max(0, session.output.length + offset) : offset;
	const end = length !== undefined ? start + length : undefined;
	return session.output.slice(start, end);
}

export function listSessions(): Array<{ pid: number; shell: string; running: boolean; lines: number; startedAt: string }> {
	return Array.from(sessions.values()).map(s => ({
		pid: s.pid,
		shell: s.shell,
		running: s.process.exitCode === null,
		lines: s.output.length,
		startedAt: s.startedAt.toISOString(),
	}));
}

export function terminateSession(pid: number): boolean {
	const session = sessions.get(pid);
	if (!session) return false;
	session.process.kill();
	sessions.delete(pid);
	return true;
}