How to add HTTP header when using template caching?

[abdus]

I'm guessing since PW skips processing template files and serves directly from /site/cache/, HTTP headers I set inside templates are ignored. Is there a hook that I can use to run code just before cached page is sent to user? Would using /site/finished.php work?

Edit: finished.php is run after page is sent, so it's not working

[abdus]

Second edit: hooking after Page::render works

<?php
wire()->addHookAfter('Page::render', function (HookEvent $e) {
    header('x: test'); // works
});