🛡️ Sentinel: [HIGH] Add Rate Limiting & Security Headers

next.config.ts

@@ -1,7 +1,31 @@
 import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
-  /* config options here */
+  async headers() {
+    return [
+      {
+        source: '/(.*)',
+        headers: [
+          {
+            key: 'X-Content-Type-Options',
+            value: 'nosniff',
+          },
+          {
+            key: 'X-Frame-Options',
+            value: 'DENY',
+          },
+          {
+            key: 'X-XSS-Protection',
+            value: '1; mode=block',
+          },
+          {
+            key: 'Referrer-Policy',
+            value: 'strict-origin-when-cross-origin',
+          },
+        ],
+      },
+    ];
+  },
 };
 
 export default nextConfig;

src/app/api/architect/chat/route.ts

@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import { z } from "zod";
 import { callOpenRouter, parseJSONResponse } from "@/lib/api/openrouter";
+import { rateLimit } from "@/lib/rate-limit";
 
 // Schema for input validation
 const ChatRequestSchema = z.object({
@@ -64,6 +65,16 @@ IMPORTANT:
 
 export async function POST(req: Request) {
   try {
+    // 1. Rate Limiting Check
+    const ip = req.headers.get("x-forwarded-for") ?? "127.0.0.1";
+    const { success } = rateLimit(ip, 10, 60000); // 10 reqs per min
+    if (!success) {
+      return NextResponse.json(
+        { error: "Too many requests. Please try again later." },
+        { status: 429 }
+      );
+    }
+
     const body = await req.json();
 
     // Validate request body

src/app/api/architect/plan/route.ts

@@ -3,6 +3,7 @@ import { z } from "zod";
 import { callOpenRouter, parseJSONResponse } from "@/lib/api/openrouter";
 import toolsDB from "@/data/tools_database.json";
 import bestPractices from "@/data/best_practices.json";
+import { rateLimit } from "@/lib/rate-limit";
 
 // Input: The User Request + The Tool ID they selected
 const PlanRequestSchema = z.object({
@@ -34,6 +35,15 @@ const PlanResponseSchema = z.object({
 
 export async function POST(req: Request) {
   try {
+    const ip = req.headers.get("x-forwarded-for") ?? "127.0.0.1";
+    const { success } = rateLimit(ip, 5, 60000); // 5 reqs per min (heavier operation)
+    if (!success) {
+      return NextResponse.json(
+        { error: "Too many requests. Please try again later." },
+        { status: 429 }
+      );
+    }
+
     const body = await req.json();
     const { userRequest, selectedToolId } = PlanRequestSchema.parse(body);
 

src/app/api/architect/select/route.ts

@@ -2,11 +2,21 @@ import { NextResponse } from "next/server";
 import { callOpenRouter, parseJSONResponse } from "@/lib/api/openrouter";
 import { SelectionRequestSchema } from "@/types/selection";
 import { filterCandidates } from "@/lib/selection/hard-filter";
+import { rateLimit } from "@/lib/rate-limit";
 
 const InputSchema = SelectionRequestSchema;
 
 export async function POST(req: Request) {
   try {
+    const ip = req.headers.get("x-forwarded-for") ?? "127.0.0.1";
+    const { success } = rateLimit(ip, 5, 60000); // 5 reqs per min (heavy logic)
+    if (!success) {
+      return NextResponse.json(
+        { error: "Too many requests. Please try again later." },
+        { status: 429 }
+      );
+    }
+
     // A. Parse Body
     const body = await req.json();
     const parsedBody = InputSchema.parse(body);

src/lib/rate-limit.ts

@@ -0,0 +1,39 @@
+
+const trackers = new Map<string, { count: number; expiresAt: number }>();
+
+/**
+ * Basic in-memory rate limiter for Next.js API routes.
+ * Note: In a serverless environment, this state is per-lambda instance.
+ * For distributed rate limiting, use Redis or a similar external store.
+ */
+export function rateLimit(ip: string, limit: number = 10, windowMs: number = 60000) {
+  const now = Date.now();
+
+  // Prevent memory leaks / DoS on memory
+  if (trackers.size > 10000) {
+    const cleanupTime = now;
+    for (const [key, data] of trackers.entries()) {
+      if (data.expiresAt < cleanupTime) {
+        trackers.delete(key);
+      }
+    }
+    // If still too big, hard reset to fail open/safe
+    if (trackers.size > 10000) {
+        trackers.clear();
+    }
+  }
+
+  const record = trackers.get(ip);
+
+  if (!record || now > record.expiresAt) {
+    trackers.set(ip, { count: 1, expiresAt: now + windowMs });
+    return { success: true };
+  }
+
+  if (record.count >= limit) {
+    return { success: false };
+  }
+
+  record.count++;
+  return { success: true };
+}