security: harden API authentication system

- Use crypto.timingSafeEqual() for API key validation (prevents timing attacks)
- Make WebSocket tokens single-use (invalidated after first validation)
- Add AUTOMAKER_HIDE_API_KEY env var to suppress API key banner in logs
- Add rate limiting to login endpoint (5 attempts/minute/IP)
- Update client to fetch short-lived wsToken for WebSocket auth
  (session tokens no longer exposed in URLs)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/server/src/lib/auth.ts

@@ -127,8 +127,9 @@ function ensureApiKey(): string {
 // API key - always generated/loaded on startup for CSRF protection
 const API_KEY = ensureApiKey();
 
-// Print API key to console for web mode users
-console.log(`
+// Print API key to console for web mode users (unless suppressed for production logging)
+if (process.env.AUTOMAKER_HIDE_API_KEY !== 'true') {
+  console.log(`
 ╔═══════════════════════════════════════════════════════════════════════╗
 ║  🔐 API Key for Web Mode Authentication                               ║
 ╠═══════════════════════════════════════════════════════════════════════╣
@@ -140,6 +141,9 @@ console.log(`
 ║  In Electron mode, authentication is handled automatically.          ║
 ╚═══════════════════════════════════════════════════════════════════════╝
 `);
+} else {
+  console.log('[Auth] API key banner hidden (AUTOMAKER_HIDE_API_KEY=true)');
+}
 
 /**
  * Generate a cryptographically secure session token
@@ -205,13 +209,17 @@ export function createWsConnectionToken(): string {
 /**
  * Validate a WebSocket connection token
  * These tokens are single-use and short-lived (5 minutes)
+ * Token is invalidated immediately after first successful use
  */
 export function validateWsConnectionToken(token: string): boolean {
   const tokenData = wsConnectionTokens.get(token);
   if (!tokenData) return false;
 
+  // Always delete the token (single-use)
+  wsConnectionTokens.delete(token);
+
+  // Check if expired
   if (Date.now() > tokenData.expiresAt) {
-    wsConnectionTokens.delete(token);
     return false;
   }
 
@@ -219,10 +227,23 @@ export function validateWsConnectionToken(token: string): boolean {
 }
 
 /**
- * Validate the API key
+ * Validate the API key using timing-safe comparison
+ * Prevents timing attacks that could leak information about the key
  */
 export function validateApiKey(key: string): boolean {
-  return key === API_KEY;
+  if (!key || typeof key !== 'string') return false;
+
+  // Both buffers must be the same length for timingSafeEqual
+  const keyBuffer = Buffer.from(key);
+  const apiKeyBuffer = Buffer.from(API_KEY);
+
+  // If lengths differ, compare against a dummy to maintain constant time
+  if (keyBuffer.length !== apiKeyBuffer.length) {
+    crypto.timingSafeEqual(apiKeyBuffer, apiKeyBuffer);
+    return false;
+  }
+
+  return crypto.timingSafeEqual(keyBuffer, apiKeyBuffer);
 }
 
 /**
@@ -270,7 +291,7 @@ function checkAuthentication(
   // Check for API key in header (Electron mode)
   const headerKey = headers['x-api-key'] as string | undefined;
   if (headerKey) {
-    if (headerKey === API_KEY) {
+    if (validateApiKey(headerKey)) {
       return { authenticated: true };
     }
     return { authenticated: false, errorType: 'invalid_api_key' };
@@ -288,7 +309,7 @@ function checkAuthentication(
   // Check for API key in query parameter (fallback)
   const queryKey = query.apiKey;
   if (queryKey) {
-    if (queryKey === API_KEY) {
+    if (validateApiKey(queryKey)) {
       return { authenticated: true };
     }
     return { authenticated: false, errorType: 'invalid_api_key' };

apps/server/src/routes/auth/index.ts

@@ -13,6 +13,7 @@
  */
 
 import { Router } from 'express';
+import type { Request } from 'express';
 import {
   validateApiKey,
   createSession,
@@ -23,6 +24,83 @@ import {
   createWsConnectionToken,
 } from '../../lib/auth.js';
 
+// Rate limiting configuration
+const RATE_LIMIT_WINDOW_MS = 60 * 1000; // 1 minute window
+const RATE_LIMIT_MAX_ATTEMPTS = 5; // Max 5 attempts per window
+
+// In-memory rate limit tracking (resets on server restart)
+const loginAttempts = new Map<string, { count: number; windowStart: number }>();
+
+// Clean up old rate limit entries periodically (every 5 minutes)
+setInterval(
+  () => {
+    const now = Date.now();
+    loginAttempts.forEach((data, ip) => {
+      if (now - data.windowStart > RATE_LIMIT_WINDOW_MS * 2) {
+        loginAttempts.delete(ip);
+      }
+    });
+  },
+  5 * 60 * 1000
+);
+
+/**
+ * Get client IP address from request
+ * Handles X-Forwarded-For header for reverse proxy setups
+ */
+function getClientIp(req: Request): string {
+  const forwarded = req.headers['x-forwarded-for'];
+  if (forwarded) {
+    // X-Forwarded-For can be a comma-separated list; take the first (original client)
+    const forwardedIp = Array.isArray(forwarded) ? forwarded[0] : forwarded.split(',')[0];
+    return forwardedIp.trim();
+  }
+  return req.ip || req.socket.remoteAddress || 'unknown';
+}
+
+/**
+ * Check if an IP is rate limited
+ * Returns { limited: boolean, retryAfter?: number }
+ */
+function checkRateLimit(ip: string): { limited: boolean; retryAfter?: number } {
+  const now = Date.now();
+  const attempt = loginAttempts.get(ip);
+
+  if (!attempt) {
+    return { limited: false };
+  }
+
+  // Check if window has expired
+  if (now - attempt.windowStart > RATE_LIMIT_WINDOW_MS) {
+    loginAttempts.delete(ip);
+    return { limited: false };
+  }
+
+  // Check if over limit
+  if (attempt.count >= RATE_LIMIT_MAX_ATTEMPTS) {
+    const retryAfter = Math.ceil((RATE_LIMIT_WINDOW_MS - (now - attempt.windowStart)) / 1000);
+    return { limited: true, retryAfter };
+  }
+
+  return { limited: false };
+}
+
+/**
+ * Record a login attempt for rate limiting
+ */
+function recordLoginAttempt(ip: string): void {
+  const now = Date.now();
+  const attempt = loginAttempts.get(ip);
+
+  if (!attempt || now - attempt.windowStart > RATE_LIMIT_WINDOW_MS) {
+    // Start new window
+    loginAttempts.set(ip, { count: 1, windowStart: now });
+  } else {
+    // Increment existing window
+    attempt.count++;
+  }
+}
+
 /**
  * Create auth routes
  *
@@ -51,8 +129,23 @@ export function createAuthRoutes(): Router {
    *
    * Validates the API key and sets a session cookie.
    * Body: { apiKey: string }
+   *
+   * Rate limited to 5 attempts per minute per IP to prevent brute force attacks.
    */
   router.post('/login', async (req, res) => {
+    const clientIp = getClientIp(req);
+
+    // Check rate limit before processing
+    const rateLimit = checkRateLimit(clientIp);
+    if (rateLimit.limited) {
+      res.status(429).json({
+        success: false,
+        error: 'Too many login attempts. Please try again later.',
+        retryAfter: rateLimit.retryAfter,
+      });
+      return;
+    }
+
     const { apiKey } = req.body as { apiKey?: string };
 
     if (!apiKey) {
@@ -63,6 +156,9 @@ export function createAuthRoutes(): Router {
       return;
     }
 
+    // Record this attempt (only for actual API key validation attempts)
+    recordLoginAttempt(clientIp);
+
     if (!validateApiKey(apiKey)) {
       res.status(401).json({
         success: false,