register_hook("pre_template", function(md_path, html_body)
    -- Check if the current markdown path is for test.md
    if md_path and md_path:match("test%.md$") then
        local banner = "<div class='plugin-banner' style='padding:10px;background:white;border:1px solid #f99;margin-bottom:12px;color:black;'>Note: served via Lua plugin banner</div>"
        return banner .. html_body
    end
    -- For other pages, return the original HTML body unchanged
    return html_body
end)