diff --git a/l4d2web/l4d2web/static/js/modal-router.js b/l4d2web/l4d2web/static/js/modal-router.js
new file mode 100644
index 0000000..7450ecd
--- /dev/null
+++ b/l4d2web/l4d2web/static/js/modal-router.js
@@ -0,0 +1,6 @@
+// URL-addressable modal router (see docs/superpowers/specs/2026-05-17-url-addressable-modals-design.md).
+// Implementation lands in subsequent tasks; this stub keeps base.html's
+// script include from 404'ing during the staged rollout.
+(function () {
+  "use strict";
+})();
diff --git a/l4d2web/l4d2web/templates/base.html b/l4d2web/l4d2web/templates/base.html
index 601fdc7..3cdbbb1 100644
--- a/l4d2web/l4d2web/templates/base.html
+++ b/l4d2web/l4d2web/templates/base.html
@@ -37,10 +37,14 @@
     <main class="container">
       {% block content %}{% endblock %}
     </main>
+    <dialog id="modal-container" class="modal modal-wide" aria-labelledby="modal-content-title">
+      <div id="modal-content"></div>
+    </dialog>
     <script src="{{ url_for('static', filename='vendor/htmx.min.js') }}"></script>
     <script src="{{ url_for('static', filename='js/csrf.js') }}"></script>
     <script src="{{ url_for('static', filename='js/sse.js') }}"></script>
     <script src="{{ url_for('static', filename='js/modal.js') }}"></script>
+    <script src="{{ url_for('static', filename='js/modal-router.js') }}"></script>
     <script src="{{ url_for('static', filename='js/file-tree.js') }}"></script>
     <script src="{{ url_for('static', filename='js/password-reveal.js') }}"></script>
     <script defer src="{{ url_for('static', filename='js/console-history.js') }}"></script>