feat: add helmet for security headers in agent0 and todo0 applications

Author: iamspathan

packages/agent0/package.json

@@ -11,12 +11,14 @@
   "dependencies": {
     "@anthropic-ai/sdk": "^0.32.0",
     "@aws-sdk/client-bedrock-runtime": "^3.709.0",
+
     "@modelcontextprotocol/sdk": "^1.19.1",
     "axios": "^1.12.2",
     "cookie-parser": "^1.4.7",
     "dotenv": "^17.2.3",
     "express": "4.18.2",
     "express-session": "1.17.3",
+    "helmet": "^8.0.0",
     "jose": "^6.1.0",
     "jsonwebtoken": "^9.0.2",
     "openid-client": "^5.7.1",

packages/agent0/src/app.ts

@@ -2,6 +2,7 @@
 import express, { Request, Response } from 'express';
 import * as path from 'path';
 import cookieParser from 'cookie-parser';
+import helmet from 'helmet';
 import { getAgentForSession } from './agent.js';
 import { OktaAuthHelper, OktaConfig, createSessionMiddleware } from './auth/okta-auth.js';
 
@@ -155,6 +156,18 @@ export class AppServer {
   // ============================================================================
 
   private setupMiddleware(): void {
+    // Security headers via helmet (uses secure defaults, we only override CSP)
+    this.app.use(helmet({
+      contentSecurityPolicy: {
+        directives: {
+          defaultSrc: ["'self'"],
+          scriptSrc: ["'self'", "https://cdn.jsdelivr.net"],
+          styleSrc: ["'self'", "'unsafe-inline'"],
+          connectSrc: ["'self'", "http://localhost:3000", "http://127.0.0.1:3000"],
+        },
+      },
+    }));
+
     this.app.use(express.json());
     this.app.use(cookieParser());
     this.app.use(createSessionMiddleware(this.config.sessionSecret));

packages/todo0/package.json

@@ -25,6 +25,7 @@
     "ejs": "^3.1.10",
     "express": "^5.1.0",
     "express-session": "^1.18.2",
+    "helmet": "^8.0.0",
     "openid-client": "^5.7.1",
     "prisma": "^6.16.3",
     "zod": "^3.22.4"

packages/todo0/src/app-server.ts

@@ -2,6 +2,7 @@ import express from 'express';
 import path from 'path';
 import bodyParser from 'body-parser';
 import session from 'express-session';
+import helmet from 'helmet';
 import { randomUUID } from 'crypto';
 import * as dotenv from 'dotenv';
 import { createRequireAuth } from './middleware/requireAuth';
@@ -125,7 +126,18 @@ const app = express();
 app.set('view engine', 'ejs');
 app.set('views', path.join(__dirname, '../views'));
 
-// Logging middleware - must come first
+// Security headers via helmet (uses secure defaults, we only override CSP for inline scripts/styles)
+app.use(helmet({
+  contentSecurityPolicy: {
+    directives: {
+      defaultSrc: ["'self'"],
+      scriptSrc: ["'self'", "'unsafe-inline'"],
+      styleSrc: ["'self'", "'unsafe-inline'"],
+    },
+  },
+}));
+
+// Logging middleware
 app.use((req, _res, next) => {
   console.log(`[REQUEST] ${req.method} ${req.url}`);
   console.log(`[REQUEST] Path: ${req.path}`);

packages/todo0/src/mcp-server.ts

@@ -2,6 +2,7 @@
 import { z } from 'zod';
 import { randomUUID } from 'node:crypto';
 import express from 'express';
+import helmet from 'helmet';
 import * as dotenv from 'dotenv';
 import * as path from 'path';
 import { mcpAuthMetadataRouter, getOAuthProtectedResourceMetadataUrl } from '@modelcontextprotocol/sdk/server/auth/router.js';
@@ -341,6 +342,11 @@ async function bootstrap(): Promise<void> {
 
   const app = express();
 
+  // Security headers via helmet (API server - restrictive CSP since no HTML served)
+  app.use(helmet({
+    contentSecurityPolicy: { directives: { defaultSrc: ["'none'"] } },
+  }));
+
   // Map to store transports by session ID
   const transports: Record<string, StreamableHTTPServerTransport> = {};
   // Map to store auth claims by session ID