feat: add pidfile management for daemon process tracking

packages/daemon/src/__tests__/pidfile.test.ts

@@ -0,0 +1,59 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import os from 'node:os';
+import fs from 'node:fs';
+import path from 'node:path';
+import { writePidfile, readPidfile, cleanPidfile, isProcessAlive } from '../pidfile.js';
+
+describe('pidfile management', () => {
+  let testDir: string;
+
+  beforeEach(() => {
+    testDir = path.join(os.tmpdir(), `visionl-pidfile-test-${Date.now()}-${Math.random().toString(36).slice(2)}`);
+    // clean up before in case previous run left files
+    try { fs.rmSync(testDir, { recursive: true, force: true }); } catch { /* ignore */ }
+    fs.mkdirSync(testDir, { recursive: true });
+  });
+
+  it('writePidfile writes pid and port files, readPidfile reads them back', () => {
+    writePidfile(12345, 9527, testDir);
+
+    const result = readPidfile(testDir);
+    expect(result).toEqual({ pid: 12345, port: 9527 });
+  });
+
+  it('readPidfile returns null when pidfile does not exist', () => {
+    const result = readPidfile(testDir);
+    expect(result).toBeNull();
+  });
+
+  it('readPidfile returns null when pidfile has invalid content', () => {
+    writePidfile(12345, 9527, testDir);
+    // overwrite with invalid data
+    fs.writeFileSync(path.join(testDir, 'daemon.pid'), 'not-a-number');
+
+    const result = readPidfile(testDir);
+    expect(result).toBeNull();
+  });
+
+  it('cleanPidfile removes both pid and port files', () => {
+    writePidfile(12345, 9527, testDir);
+
+    cleanPidfile(testDir);
+
+    expect(fs.existsSync(path.join(testDir, 'daemon.pid'))).toBe(false);
+    expect(fs.existsSync(path.join(testDir, 'daemon.port'))).toBe(false);
+  });
+
+  it('cleanPidfile is safe when files do not exist', () => {
+    // should not throw
+    expect(() => cleanPidfile(testDir)).not.toThrow();
+  });
+
+  it('isProcessAlive returns true for the current process', () => {
+    expect(isProcessAlive(process.pid)).toBe(true);
+  });
+
+  it('isProcessAlive returns false for a non-existent PID', () => {
+    expect(isProcessAlive(99999999)).toBe(false);
+  });
+});

packages/daemon/src/pidfile.ts

@@ -0,0 +1,48 @@
+import fs from 'node:fs';
+import path from 'node:path';
+import os from 'node:os';
+
+const DEFAULT_DIR = path.join(os.homedir(), '.visionl');
+
+function ensureDir(dir: string): void {
+  if (!fs.existsSync(dir)) {
+    fs.mkdirSync(dir, { recursive: true });
+  }
+}
+
+export function writePidfile(pid: number, port: number, dir: string = DEFAULT_DIR): void {
+  ensureDir(dir);
+  fs.writeFileSync(path.join(dir, 'daemon.pid'), String(pid));
+  fs.writeFileSync(path.join(dir, 'daemon.port'), String(port));
+}
+
+export function readPidfile(dir: string = DEFAULT_DIR): { pid: number; port: number } | null {
+  const pidPath = path.join(dir, 'daemon.pid');
+  const portPath = path.join(dir, 'daemon.port');
+  try {
+    const pid = parseInt(fs.readFileSync(pidPath, 'utf-8'), 10);
+    const port = parseInt(fs.readFileSync(portPath, 'utf-8'), 10);
+    if (isNaN(pid) || isNaN(port)) return null;
+    return { pid, port };
+  } catch {
+    return null;
+  }
+}
+
+export function cleanPidfile(dir: string = DEFAULT_DIR): void {
+  try {
+    fs.unlinkSync(path.join(dir, 'daemon.pid'));
+    fs.unlinkSync(path.join(dir, 'daemon.port'));
+  } catch {
+    // Ignore if files don't exist
+  }
+}
+
+export function isProcessAlive(pid: number): boolean {
+  try {
+    process.kill(pid, 0);
+    return true;
+  } catch {
+    return false;
+  }
+}