feat: add dynamic user-agent version updater

- Add user-agent-updater.js to automatically fetch latest factory-cli version
- Fetch version from https://downloads.factory.ai/factory-cli/LATEST on startup
- Automatically refresh version every hour
- Implement retry mechanism: max 3 retries with 1-minute intervals on failure
- Use user_agent from config.json as fallback value
- Update config.js to use dynamic user-agent
- Initialize updater in server.js startup sequence

config.js

@@ -2,6 +2,7 @@ import fs from 'fs';
 import path from 'path';
 import { fileURLToPath } from 'url';
 import { logInfo } from './logger.js';
+import { getCurrentUserAgent } from './user-agent-updater.js';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
@@ -64,8 +65,7 @@ export function getModelReasoning(modelId) {
 }
 
 export function getUserAgent() {
-  const cfg = getConfig();
-  return cfg.user_agent || 'factory-cli/0.19.3';
+  return getCurrentUserAgent();
 }
 
 export function getProxyConfigs() {

server.js

@@ -3,6 +3,7 @@ import { loadConfig, isDevMode, getPort } from './config.js';
 import { logInfo, logError } from './logger.js';
 import router from './routes.js';
 import { initializeAuth } from './auth.js';
+import { initializeUserAgentUpdater } from './user-agent-updater.js';
 
 const app = express();
 
@@ -112,6 +113,9 @@ app.use((err, req, res, next) => {
     logInfo('Configuration loaded successfully');
     logInfo(`Dev mode: ${isDevMode()}`);
     
+    // Initialize User-Agent version updater
+    initializeUserAgentUpdater();
+    
     // Initialize auth system (load and setup API key if needed)
     // This won't throw error if no auth config is found - will use client auth
     await initializeAuth();

user-agent-updater.js

@@ -0,0 +1,114 @@
+import https from 'https';
+import { logInfo, logError } from './logger.js';
+import { getConfig } from './config.js';
+
+const VERSION_URL = 'https://downloads.factory.ai/factory-cli/LATEST';
+const USER_AGENT_PREFIX = 'factory-cli';
+const CHECK_INTERVAL = 60 * 60 * 1000; // 1 hour
+const RETRY_INTERVAL = 60 * 1000; // 1 minute
+const MAX_RETRIES = 3;
+
+let currentVersion = null;
+let isUpdating = false;
+
+function getDefaultVersion() {
+  const cfg = getConfig();
+  const userAgent = cfg.user_agent || 'factory-cli/0.19.3';
+  const match = userAgent.match(/\/(\d+\.\d+\.\d+)/);
+  return match ? match[1] : '0.19.3';
+}
+
+function initializeVersion() {
+  if (currentVersion === null) {
+    currentVersion = getDefaultVersion();
+  }
+}
+
+export function getCurrentUserAgent() {
+  initializeVersion();
+  return `${USER_AGENT_PREFIX}/${currentVersion}`;
+}
+
+function fetchLatestVersion() {
+  return new Promise((resolve, reject) => {
+    const request = https.get(VERSION_URL, (res) => {
+      let data = '';
+
+      if (res.statusCode !== 200) {
+        reject(new Error(`HTTP ${res.statusCode}`));
+        return;
+      }
+
+      res.on('data', (chunk) => {
+        data += chunk;
+      });
+
+      res.on('end', () => {
+        const version = data.trim();
+        if (version && /^\d+\.\d+\.\d+/.test(version)) {
+          resolve(version);
+        } else {
+          reject(new Error(`Invalid version format: ${version}`));
+        }
+      });
+    });
+
+    request.on('error', (err) => {
+      reject(err);
+    });
+
+    request.setTimeout(10000, () => {
+      request.destroy();
+      reject(new Error('Request timeout'));
+    });
+  });
+}
+
+async function updateVersionWithRetry(retryCount = 0) {
+  if (isUpdating) {
+    return;
+  }
+
+  isUpdating = true;
+
+  try {
+    const version = await fetchLatestVersion();
+    if (version !== currentVersion) {
+      const oldVersion = currentVersion;
+      currentVersion = version;
+      logInfo(`User-Agent version updated: ${oldVersion} -> ${currentVersion}`);
+    } else {
+      logInfo(`User-Agent version is up to date: ${currentVersion}`);
+    }
+    isUpdating = false;
+  } catch (error) {
+    logError(`Failed to fetch latest version (attempt ${retryCount + 1}/${MAX_RETRIES})`, error);
+
+    if (retryCount < MAX_RETRIES - 1) {
+      logInfo(`Retrying in 1 minute...`);
+      setTimeout(() => {
+        updateVersionWithRetry(retryCount + 1);
+      }, RETRY_INTERVAL);
+    } else {
+      logError(`Max retries reached. Will try again in next hourly check.`);
+      isUpdating = false;
+    }
+  }
+}
+
+export function initializeUserAgentUpdater() {
+  initializeVersion();
+  logInfo('Initializing User-Agent version updater...');
+  logInfo(`Default User-Agent from config: ${USER_AGENT_PREFIX}/${currentVersion}`);
+
+  // Fetch immediately on startup
+  updateVersionWithRetry();
+
+  // Schedule hourly checks
+  setInterval(() => {
+    logInfo('Running scheduled User-Agent version check...');
+    updateVersionWithRetry();
+  }, CHECK_INTERVAL);
+
+  logInfo(`User-Agent updater initialized. Will check every hour.`);
+}