feat: add hot reload for development mode

package.json

@@ -35,7 +35,8 @@
         "pm2:delete": "pm2 delete process.json",
         "test": "vitest run",
         "test:watch": "vitest",
-        "test:coverage": "vitest run --coverage"
+        "test:coverage": "vitest run --coverage",
+        "dev": "npm run build && node --enable-source-maps dist/watch.js"
     },
     "dependencies": {
         "@discordjs/rest": "^2.6.0",

src/watch.ts

@@ -0,0 +1,117 @@
+import { spawn } from 'node:child_process';
+import { watch } from 'node:fs';
+import { basename } from 'node:path';
+
+const BOT_ENTRY = 'dist/start-bot.js';
+const SRC_DIR = 'src';
+
+// Track running bot process
+let botProcess: ReturnType<typeof spawn> | null = null;
+let isRestarting = false;
+
+function log(message: string): void {
+    console.log(`[Watch] ${message}`);
+}
+
+function startBot(): void {
+    if (botProcess) {
+        log('Restarting bot...');
+        botProcess.kill('SIGTERM');
+        botProcess = null;
+    }
+
+    log('Starting bot...');
+    botProcess = spawn('node', ['--enable-source-maps', BOT_ENTRY], {
+        stdio: 'inherit',
+        shell: true,
+    });
+
+    botProcess.on('exit', (code, signal) => {
+        if (signal === 'SIGTERM' || code === 143) {
+            // Expected termination (our restart)
+            return;
+        }
+        log(`Bot exited with code ${code}, signal ${signal}`);
+        if (!isRestarting) {
+            log('Bot crashed. Fix the error and save a file to restart.');
+        }
+    });
+
+    botProcess.on('error', (err) => {
+        log(`Bot process error: ${err.message}`);
+    });
+}
+
+function buildAndStart(): void {
+    if (isRestarting) return;
+    isRestarting = true;
+
+    log('File change detected, rebuilding...');
+
+    const build = spawn('npm', ['run', 'build'], {
+        stdio: 'inherit',
+        shell: true,
+    });
+
+    build.on('exit', (code) => {
+        if (code === 0) {
+            startBot();
+        } else {
+            log(`Build failed with code ${code}. Waiting for file changes to retry...`);
+        }
+        isRestarting = false;
+    });
+
+    build.on('error', (err) => {
+        log(`Build error: ${err.message}`);
+        isRestarting = false;
+    });
+}
+
+// Watch source directory
+log(`Watching ${SRC_DIR}/ for changes...`);
+
+const watcher = watch(SRC_DIR, { recursive: true }, (eventType, filename) => {
+    if (!filename) return;
+
+    // Ignore non-TypeScript files and generated files
+    const ignored = [
+        '.js.map',
+        '.d.ts',
+        '.d.ts.map',
+    ];
+
+    const ext = filename.split('.').pop();
+    if (ext && !filename.endsWith('.ts') && ext !== 'cts' && ext !== 'mts') {
+        return;
+    }
+
+    for (const ignore of ignored) {
+        if (filename.endsWith(ignore)) return;
+    }
+
+    log(`Change detected in ${filename} (${eventType}), rebuilding...`);
+    buildAndStart();
+});
+
+// Handle graceful shutdown
+process.on('SIGINT', () => {
+    log('Shutting down watcher...');
+    if (botProcess) {
+        botProcess.kill('SIGTERM');
+    }
+    watcher.close();
+    process.exit(0);
+});
+
+process.on('SIGTERM', () => {
+    log('Shutting down watcher...');
+    if (botProcess) {
+        botProcess.kill('SIGTERM');
+    }
+    watcher.close();
+    process.exit(0);
+});
+
+// Start the bot initially
+startBot();