By: Michael Lynch <git@mtlynch.io>
Prefetch adjacent images via JS to fix Firefox CSP compatibility <link rel="prefetch"> CSP behaviour varies by browser: Chrome 112+ uses the type-based img-src directive (so it worked), while Firefox falls back to default-src, which only allows 'self' and therefore blocked cross-origin S3/CDN prefetch requests. prefetch-src is not implemented in Firefox, so adding that directive to the CSP has no effect there. Replace the <link rel="prefetch"> tags with new Image() calls in JS. Image() loads are governed by img-src in all browsers, which already includes the media origin. The adjacent-image URLs are rendered as data attributes on the content element (per the project convention of not embedding Go template conditionals in JavaScript) and the JS reads them after DOMContentLoaded. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>