feat(csp): allow chat UI to be embedded in iframes (#3643)

* feat(csp): allow chat UI to be embedded in iframes

Mirror the existing form embed CSP pattern for chat pages: add
getChatEmbedCSPPolicy() with frame-ancestors *, configure /chat/:path*
headers in next.config.ts without X-Frame-Options, and early-return in
proxy.ts so chat routes skip the strict runtime CSP.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor(csp): extract shared getEmbedCSPPolicy helper

Deduplicate getChatEmbedCSPPolicy and getFormEmbedCSPPolicy into a
shared private helper to prevent future divergence.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

apps/sim/lib/core/security/csp.ts

@@ -202,15 +202,28 @@ export function getWorkflowExecutionCSPPolicy(): string {
 }
 
 /**
- * CSP for embeddable form pages
+ * Shared CSP for embeddable pages (chat, forms)
  * Allows embedding in iframes from any origin while maintaining other security policies
  */
-export function getFormEmbedCSPPolicy(): string {
-  const basePolicy = buildCSPString({
+function getEmbedCSPPolicy(): string {
+  return buildCSPString({
     ...buildTimeCSPDirectives,
     'frame-ancestors': ['*'],
   })
-  return basePolicy
+}
+
+/**
+ * CSP for embeddable chat pages
+ */
+export function getChatEmbedCSPPolicy(): string {
+  return getEmbedCSPPolicy()
+}
+
+/**
+ * CSP for embeddable form pages
+ */
+export function getFormEmbedCSPPolicy(): string {
+  return getEmbedCSPPolicy()
 }
 
 /**

apps/sim/next.config.ts

@@ -2,6 +2,7 @@ import type { NextConfig } from 'next'
 import { env, getEnv, isTruthy } from './lib/core/config/env'
 import { isDev } from './lib/core/config/feature-flags'
 import {
+  getChatEmbedCSPPolicy,
   getFormEmbedCSPPolicy,
   getMainCSPPolicy,
   getWorkflowExecutionCSPPolicy,
@@ -255,6 +256,24 @@ const nextConfig: NextConfig = {
           },
         ],
       },
+      // Chat pages - allow iframe embedding from any origin
+      {
+        source: '/chat/:path*',
+        headers: [
+          {
+            key: 'X-Content-Type-Options',
+            value: 'nosniff',
+          },
+          // No X-Frame-Options to allow iframe embedding
+          {
+            key: 'Content-Security-Policy',
+            value: getChatEmbedCSPPolicy(),
+          },
+          // Permissive CORS for chat requests from embedded chats
+          { key: 'Cross-Origin-Embedder-Policy', value: 'unsafe-none' },
+          { key: 'Cross-Origin-Opener-Policy', value: 'unsafe-none' },
+        ],
+      },
       // Form pages - allow iframe embedding from any origin
       {
         source: '/form/:path*',
@@ -284,10 +303,10 @@ const nextConfig: NextConfig = {
         ],
       },
       // Apply security headers to routes not handled by middleware runtime CSP
-      // Middleware handles: /, /workspace/*, /chat/*
-      // Exclude form routes which have their own permissive headers
+      // Middleware handles: /, /workspace/*
+      // Exclude chat and form routes which have their own permissive embed headers
       {
-        source: '/((?!workspace|chat$|form).*)',
+        source: '/((?!workspace|chat|form).*)',
         headers: [
           {
             key: 'X-Content-Type-Options',

apps/sim/proxy.ts

@@ -155,6 +155,7 @@ export async function proxy(request: NextRequest) {
     return response
   }
 
+  // Chat pages are publicly accessible embeds — CSP is set in next.config.ts headers
   if (url.pathname.startsWith('/chat/')) {
     return NextResponse.next()
   }
@@ -188,11 +189,7 @@ export async function proxy(request: NextRequest) {
   const response = NextResponse.next()
   response.headers.set('Vary', 'User-Agent')
 
-  if (
-    url.pathname.startsWith('/workspace') ||
-    url.pathname.startsWith('/chat') ||
-    url.pathname === '/'
-  ) {
+  if (url.pathname.startsWith('/workspace') || url.pathname === '/') {
     response.headers.set('Content-Security-Policy', generateRuntimeCSP())
   }