auto-claude: subtask-2-3 - Add IP extraction utility for Next.js requests

src/utils/getClientIp.ts

@@ -0,0 +1,33 @@
+import { NextRequest } from 'next/server';
+
+/**
+ * Extract client IP address from Next.js request headers
+ *
+ * This function handles various proxy and forwarding scenarios:
+ * - Vercel's x-forwarded-for header (may contain multiple IPs)
+ * - x-real-ip header (direct client IP)
+ * - Fallback for development environments
+ *
+ * @param request - Next.js request object
+ * @returns Client IP address as a string, or 'unknown-ip' as fallback
+ */
+export function getClientIp(request: NextRequest): string {
+  // Check Vercel's forwarded IP header first
+  // In production, this is the most reliable source
+  const forwardedFor = request.headers.get('x-forwarded-for');
+  if (forwardedFor) {
+    // x-forwarded-for may contain multiple IPs in format: "client, proxy1, proxy2"
+    // The first IP is the original client IP
+    return forwardedFor.split(',')[0].trim();
+  }
+
+  // Check for real IP header (used by some proxies and load balancers)
+  const realIp = request.headers.get('x-real-ip');
+  if (realIp) {
+    return realIp;
+  }
+
+  // Fallback to a default identifier for development environments
+  // or when headers are not available
+  return 'unknown-ip';
+}