Index: src/views/shell.ejs
===================================================================
--- src/views/shell.ejs	(revision ccbd6a67197d7fdb179b5f427667654b00df27ae)
+++ src/views/shell.ejs	(revision a64f642ec61d1349904508f7af00155c05bd3c72)
@@ -238,4 +238,10 @@
 
 <body class="<%= bodyClass || 'on-home' %> has-bottom-tab" data-feed-view="<%= _e(safeSite.feed_view_default || 'timeline') %>" data-grid-cols="3">
+
+<% if (user && user.readonly) { %>
+  <div style="position:sticky;top:0;z-index:50;background:#e8b04b;color:#1a1a1a;text-align:center;font-size:0.85rem;font-weight:600;padding:0.4rem 1rem;">
+    👁️ Demo — alleen-lezen: je kunt alles bekijken, maar niets wijzigen.
+  </div>
+<% } %>
 
 <%# Geen shell-chrome (masthead/profile-header/view-switcher/bottom-tab) op:
