next.config.mjs

const isProd = process.env.NODE_ENV === 'production'

// Always-safe security headers (also fine during local dev).
const baseHeaders = [
  { key: 'X-Frame-Options', value: 'SAMEORIGIN' },
  { key: 'X-Content-Type-Options', value: 'nosniff' },
  { key: 'Referrer-Policy', value: 'strict-origin-when-cross-origin' },
  { key: 'Permissions-Policy', value: 'camera=(), microphone=(), geolocation=()' },
  { key: 'X-DNS-Prefetch-Control', value: 'on' },
]

// Stricter headers only in production (would interfere with dev HMR / eval).
const prodHeaders = isProd
  ? [
      { key: 'Strict-Transport-Security', value: 'max-age=63072000; includeSubDomains; preload' },
      {
        key: 'Content-Security-Policy',
        value: [
          "default-src 'self'",
          "script-src 'self' 'unsafe-inline'",
          "style-src 'self' 'unsafe-inline'",
          "img-src 'self' data: blob:",
          "font-src 'self'",
          // Allow Supabase REST/Auth (https) and Realtime (wss)
          "connect-src 'self' https://*.supabase.co wss://*.supabase.co",
          "frame-ancestors 'self'",
          "base-uri 'self'",
          "form-action 'self'",
        ].join('; '),
      },
    ]
  : []

/** @type {import('next').NextConfig} */
const nextConfig = {
  reactStrictMode: true,
  poweredByHeader: false,
  async headers() {
    return [{ source: '/:path*', headers: [...baseHeaders, ...prodHeaders] }]
  },
}

export default nextConfig