inspiration:
perishablepress.com/better-default-directory-views-with-htaccess/

apache-conf:

IndexOptions SuppressHTMLPreamble FancyIndexing
HeaderName /dirlist-header.html

shell vscode remote:

code /etc/apache2/sites-enabled/000-default-le-ssl.conf
apachectl restart

php (disabled):
[php $dir = explode('?', $_SERVER['REQUEST_URI']) [0]; ]
[= $dir ]
/dirlist-header.html contents: [[
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <?php $dir = explode('?', $_SERVER['REQUEST_URI']) [0]; ?>
    <title>
        <?= $dir ?> dir-list
    </title>
    <link rel="stylesheet" href="/sitewide.css">
</head>

<body>

    <?php require("search.html"); ?>

    <a href="/coder.html">author</a>

    <a href="/"> beginning </a> <a href="javascript:history.back()"> go back </a>

    <h1>
        <?= $dir ?> dir-list
    </h1>
]]