[scriptogre]

Problem

htmx 4 sends HX-Request-Type: full when hx-target is <body>, or when hx-select is used.

Otherwise, it sends HX-Request-Type: partial.

hx-boost makes an htmx request with an implicit hx-target="body", and thus it sends HX-Request-Type: full.

FastHTML sees HX-Request and treats this as a fragment request. It renders <head> children directly alongside body content:

<title>Settings</title>
<link rel="stylesheet" href="/settings.css">
<main>...</main>

Instead of placing them inside <head> in a complete <html> document:

<html>
 <head>
   <title>Settings</title>
   <link rel="stylesheet" href="/settings.css">
 </head>
 <body>
   <main>...</main>
 </body>
</html>

Fix

Render the full <html> when HX-Request-Type: full header is present.

Also add HX-Request-Type to Vary so caches separate full-page and fragment responses.