New markup over an old stylesheet

Reported from a desktop browser: a stray close button beside the logo, badly
drawn, and a page that would not scroll. None of it was in the code that was
running -- it was the code the browser had not fetched.

The worker caches /static/ under a cache named for the release while the files
in it carried no version, and a page is fetched network-first. That only ever
worked because the worker used to seize every open tab the instant it installed
and wipe the old cache. 1.1.0 stopped it doing that, rightly -- it was swapping
stylesheets out from under a streaming reply -- and a momentary mismatch became
a permanent one: new markup over the previous release's CSS for as long as the
old worker lived. `.sidebar__close` had no rule there, so `.btn--icon` made it
inline-flex: visible everywhere, placed by nothing.

Every /static/ URL carries the release now, written by `templating.asset` and
precached by `sw.js:versioned` -- both halves, because caches.match compares the
query too and precaching the bare path would cache entries nothing requests.
Self-correcting: updating is enough.

The header was also a brand with a button appended and margin-left:auto doing
the placing, which holds exactly while that button is last. Two slots now: a
brand that shrinks and truncates, and a rail on the trailing edge.

Verified before changing anything: with the current stylesheet the button is
display:none at 1280 and, with thirty chats and forty messages, both scrollers
scroll. The first measurement said the thread did not -- that was
scroll-behavior: smooth reporting where it started.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/lembas/__init__.py

@@ -1,3 +1,3 @@
 """LLeMbas - a Middle-earth themed web UI for OpenAI-compatible LLM endpoints."""
 
-__version__ = "1.1.0"
+__version__ = "1.1.1"

src/lembas/web/static/css/app.css

@@ -446,13 +446,40 @@ button, input, textarea, select {
 }
 .sidebar[hidden] { display: none; }
 
+/*
+  Two slots with a gap between them, and neither is positioned against the
+  other. The brand shrinks and truncates because its width is an instance
+  setting nobody here chose; the rail does not, because it is a whole number of
+  `--control-h` boxes and is the thing a hand is going for.
+
+  `gap` rather than `margin-left: auto` on the last child: auto-margin puts the
+  rail on the trailing edge only for as long as it happens to be last, and the
+  moment a second control is added it lands between the brand and the rail
+  instead of in it.
+*/
 .sidebar__header {
   display: flex;
   align-items: center;
+  gap: var(--sp-2);
   height: var(--header-height);
   padding: 0 var(--sp-3);
   flex: none;
 }
+.sidebar__brand-slot {
+  flex: 1 1 auto;
+  min-width: 0;
+  display: flex;
+  align-items: center;
+}
+/* On the trailing edge, whatever the writing direction, and sized by its
+   contents rather than by what is left over. */
+.sidebar__actions-rail {
+  flex: none;
+  display: flex;
+  align-items: center;
+  gap: var(--sp-1);
+  margin-inline-start: auto;
+}
 .sidebar__brand {
   display: flex;
   align-items: center;
@@ -1257,7 +1284,6 @@ body.is-resizing .canvas__body { pointer-events: none; }
 
   .sidebar__close {
     display: inline-flex;
-    margin-left: auto;
   }
 
   /* Dismissible by tapping beside it. Without this the only way out is a

src/lembas/web/static/js/sw.js

@@ -50,6 +50,18 @@ var SHELL = [
   "/static/img/apple-touch-icon-180.png",
 ];
 
+/* The URL a page will actually ask for.
+
+   Every `/static/` link carries `?v=<release>` -- see `templating.asset` -- and
+   `caches.match` compares the whole URL, query included. So precaching the bare
+   path would fill the cache with entries no page ever requests, and every asset
+   would go to the network on every load while looking perfectly cached.
+
+   `/offline` is a route rather than an asset and is left alone. */
+function versioned(path) {
+  return path.indexOf("/static/") === 0 ? path + "?v=" + VERSION : path;
+}
+
 self.addEventListener("install", function (event) {
   event.waitUntil(
     caches.open(CACHE).then(function (cache) {
@@ -57,7 +69,8 @@ self.addEventListener("install", function (event) {
       // and the whole feature silently off, so each entry is added on its own.
       return Promise.all(
         SHELL.map(function (path) {
-          return cache.add(new Request(path, { cache: "reload" })).catch(function () {});
+          return cache.add(new Request(versioned(path), { cache: "reload" }))
+            .catch(function () {});
         })
       );
     })

src/lembas/web/templates/admin/_layout.html

@@ -6,8 +6,8 @@
 #}
 
 {% block head %}
-<link rel="stylesheet" href="{{ url_for('static', path='css/chat.css') }}">
-<link rel="stylesheet" href="{{ url_for('static', path='css/admin.css') }}">
+<link rel="stylesheet" href="{{ asset('css/chat.css') }}">
+<link rel="stylesheet" href="{{ asset('css/admin.css') }}">
 {% endblock %}
 
 {% block body_attrs %} data-authenticated="true"{% endblock %}

src/lembas/web/templates/agents/_layout.html

@@ -9,8 +9,8 @@
 #}
 
 {% block head %}
-<link rel="stylesheet" href="{{ url_for('static', path='css/chat.css') }}">
-<link rel="stylesheet" href="{{ url_for('static', path='css/admin.css') }}">
+<link rel="stylesheet" href="{{ asset('css/chat.css') }}">
+<link rel="stylesheet" href="{{ asset('css/admin.css') }}">
 {% endblock %}
 
 {% block body_attrs %} data-authenticated="true"{% endblock %}

src/lembas/web/templates/base.html

@@ -34,7 +34,7 @@
 {% elif brand.icon_paths.favicon %}
 <link rel="icon" href="/branding/{{ brand.icon_paths.favicon }}">
 {% else %}
-<link rel="icon" href="{{ url_for('static', path='img/favicon.svg') }}" type="image/svg+xml">
+<link rel="icon" href="{{ asset('img/favicon.svg') }}" type="image/svg+xml">
 {% endif %}
 
 {#
@@ -57,15 +57,15 @@
 {% if brand.icon_paths['apple-touch'] %}
 <link rel="apple-touch-icon" href="/branding/{{ brand.icon_paths['apple-touch'] }}">
 {% else %}
-<link rel="apple-touch-icon" href="{{ url_for('static', path='img/apple-touch-icon-180.png') }}">
+<link rel="apple-touch-icon" href="{{ asset('img/apple-touch-icon-180.png') }}">
 {% endif %}
 <meta name="apple-mobile-web-app-capable" content="yes">
 <meta name="mobile-web-app-capable" content="yes">
 <meta name="apple-mobile-web-app-title" content="{{ brand.name }}">
 <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
 
-<link rel="stylesheet" href="{{ url_for('static', path='css/tokens.css') }}">
-<link rel="stylesheet" href="{{ url_for('static', path='css/app.css') }}">
+<link rel="stylesheet" href="{{ asset('css/tokens.css') }}">
+<link rel="stylesheet" href="{{ asset('css/app.css') }}">
 {#
   Last, so an administrator's rules win, and before {% block head %} so a page's
   own stylesheet still comes after it. The query string is a hash of everything
@@ -128,16 +128,16 @@
 
 {% block body %}{% endblock %}
 
-<script src="{{ url_for('static', path='vendor/htmx.min.js') }}" defer></script>
-<script src="{{ url_for('static', path='vendor/htmx-ext-sse.js') }}" defer></script>
-<script src="{{ url_for('static', path='vendor/alpine.min.js') }}" defer></script>
-<script src="{{ url_for('static', path='js/app.js') }}" defer></script>
-<script src="{{ url_for('static', path='js/ui.js') }}" defer></script>
+<script src="{{ asset('vendor/htmx.min.js') }}" defer></script>
+<script src="{{ asset('vendor/htmx-ext-sse.js') }}" defer></script>
+<script src="{{ asset('vendor/alpine.min.js') }}" defer></script>
+<script src="{{ asset('js/app.js') }}" defer></script>
+<script src="{{ asset('js/ui.js') }}" defer></script>
 {# commands.js before composer.js: the second reads the first's table to draw
    the `/` menu, and both are deferred so the order here is the run order. #}
-<script src="{{ url_for('static', path='js/commands.js') }}" defer></script>
-<script src="{{ url_for('static', path='js/composer.js') }}" defer></script>
-<script src="{{ url_for('static', path='js/audio.js') }}" defer></script>
+<script src="{{ asset('js/commands.js') }}" defer></script>
+<script src="{{ asset('js/composer.js') }}" defer></script>
+<script src="{{ asset('js/audio.js') }}" defer></script>
 
 {#
   The version in the query string is what versions the worker's cache, so a

src/lembas/web/templates/chat/index.html

@@ -4,9 +4,9 @@
 {% block title %}{{ chat.title if chat else "New chat" }} - {{ brand.name }}{% endblock %}
 
 {% block head %}
-<link rel="stylesheet" href="{{ url_for('static', path='css/chat.css') }}">
+<link rel="stylesheet" href="{{ asset('css/chat.css') }}">
 {% if terminal_enabled %}
-<link rel="stylesheet" href="{{ url_for('static', path='vendor/xterm.css') }}">
+<link rel="stylesheet" href="{{ asset('vendor/xterm.css') }}">
 {% endif %}
 {% endblock %}
 
@@ -393,21 +393,21 @@
 {% block scripts %}
 {# Unconditional: every chat has a transcript, and this is what keeps a block
    somebody opened open across the swaps that arrive twelve times a second. #}
-<script src="{{ url_for('static', path='js/steps.js') }}" defer></script>
+<script src="{{ asset('js/steps.js') }}" defer></script>
 {% if not chat and (canvas_enabled or terminal_enabled) %}
 {# Only where there is no chat yet. It points both panels at a draft id for
    whatever the composer has selected, and does nothing at all once a chat
    exists -- which is every other page this block renders on. #}
-<script src="{{ url_for('static', path='js/draft.js') }}" defer></script>
+<script src="{{ asset('js/draft.js') }}" defer></script>
 {% endif %}
 {% if canvas_enabled %}
-<script src="{{ url_for('static', path='js/canvas.js') }}" defer></script>
+<script src="{{ asset('js/canvas.js') }}" defer></script>
 {% endif %}
 {% if terminal_enabled %}
 {# Only where it can be used. xterm is nearly three times everything else
    vendored, so a plain chat must never load it. #}
-<script src="{{ url_for('static', path='vendor/xterm.js') }}" defer></script>
-<script src="{{ url_for('static', path='vendor/xterm-addon-fit.js') }}" defer></script>
-<script src="{{ url_for('static', path='js/terminal.js') }}" defer></script>
+<script src="{{ asset('vendor/xterm.js') }}" defer></script>
+<script src="{{ asset('vendor/xterm-addon-fit.js') }}" defer></script>
+<script src="{{ asset('js/terminal.js') }}" defer></script>
 {% endif %}
 {% endblock %}

src/lembas/web/templates/folders/edit.html

@@ -17,8 +17,8 @@
 {% block title %}{{ folder.name }} - {{ brand.name }}{% endblock %}
 
 {% block head %}
-<link rel="stylesheet" href="{{ url_for('static', path='css/chat.css') }}">
-<link rel="stylesheet" href="{{ url_for('static', path='css/admin.css') }}">
+<link rel="stylesheet" href="{{ asset('css/chat.css') }}">
+<link rel="stylesheet" href="{{ asset('css/admin.css') }}">
 {% endblock %}
 
 {% block body_attrs %} data-authenticated="true"{% endblock %}

src/lembas/web/templates/library/_layout.html

@@ -9,8 +9,8 @@
 #}
 
 {% block head %}
-<link rel="stylesheet" href="{{ url_for('static', path='css/chat.css') }}">
-<link rel="stylesheet" href="{{ url_for('static', path='css/admin.css') }}">
+<link rel="stylesheet" href="{{ asset('css/chat.css') }}">
+<link rel="stylesheet" href="{{ asset('css/admin.css') }}">
 {% endblock %}
 
 {% block body_attrs %} data-authenticated="true"{% endblock %}

src/lembas/web/templates/messages/index.html

@@ -13,7 +13,7 @@
 {% block title %}Messages - {{ brand.name }}{% endblock %}
 
 {% block head %}
-<link rel="stylesheet" href="{{ url_for('static', path='css/chat.css') }}">
+<link rel="stylesheet" href="{{ asset('css/chat.css') }}">
 {% endblock %}
 
 {% block body_attrs %} data-authenticated="true"{% endblock %}
@@ -124,5 +124,5 @@
   DOM stub, which is the rule the working notes set out and the reason it does.
 #}
 {% block scripts %}
-<script src="{{ url_for('static', path='js/steps.js') }}" defer></script>
+<script src="{{ asset('js/steps.js') }}" defer></script>
 {% endblock %}

src/lembas/web/templates/partials/sidebar.html

@@ -7,8 +7,26 @@
   nothing behind.
 #}
 <aside class="sidebar" id="sidebar">
-  <div class="sidebar__header">
-    {{ brandlink(uid="side") }}
+  {#
+    The header is two slots, not a brand with something appended to it.
+
+    `__brand` holds the identity and is the only part allowed to shrink;
+    `__actions` is a fixed-width rail on the trailing edge that anything
+    belonging to the drawer itself hangs off. It is a rail rather than one
+    button because a second one -- pin the sidebar open, a search -- would
+    otherwise be appended to the brand again, and the alignment would be a
+    coincidence for the third time.
+
+    This is the standing rule about rows applied to a row that got it wrong:
+    the two parts have a known width (a rail of `--control-h` boxes) and an
+    unknown one (a name somebody chose), so the unknown one is the one that
+    gives, and the rail is `flex: none`.
+  #}
+  <header class="sidebar__header">
+    <div class="sidebar__brand-slot">
+      {{ brandlink(uid="side") }}
+    </div>
+
     {#
       The way out, and the reason it is *inside* the drawer.
 
@@ -19,13 +37,18 @@
       sidebar there was no such control at all, and no way back.
 
       Hidden above that breakpoint, where the sidebar is an ordinary column and
-      the topbar's toggle is perfectly visible.
+      the topbar's toggle is perfectly visible. It shipped *visible* on the
+      desktop in 1.1.0 -- not because this rule was wrong, but because the
+      browser was still drawing the page with the previous release's
+      stylesheet; see `templating.asset`.
     #}
-    <button class="btn btn--icon sidebar__close" type="button"
-            aria-label="Close sidebar" data-toggle="#sidebar">
-      {{ icon("x") }}
-    </button>
-  </div>
+    <div class="sidebar__actions-rail">
+      <button class="btn btn--icon sidebar__close" type="button"
+              aria-label="Close sidebar" data-toggle="#sidebar">
+        {{ icon("x") }}
+      </button>
+    </div>
+  </header>
 
   {% include "partials/_sidebar_actions.html" %}
 

src/lembas/web/templates/reports/_layout.html

@@ -15,8 +15,8 @@
 #}
 
 {% block head %}
-<link rel="stylesheet" href="{{ url_for('static', path='css/chat.css') }}">
-<link rel="stylesheet" href="{{ url_for('static', path='css/admin.css') }}">
+<link rel="stylesheet" href="{{ asset('css/chat.css') }}">
+<link rel="stylesheet" href="{{ asset('css/admin.css') }}">
 {% endblock %}
 
 {% block body_attrs %} data-authenticated="true"{% endblock %}

src/lembas/web/templates/schedules/_layout.html

@@ -8,8 +8,8 @@
 #}
 
 {% block head %}
-<link rel="stylesheet" href="{{ url_for('static', path='css/chat.css') }}">
-<link rel="stylesheet" href="{{ url_for('static', path='css/admin.css') }}">
+<link rel="stylesheet" href="{{ asset('css/chat.css') }}">
+<link rel="stylesheet" href="{{ asset('css/admin.css') }}">
 {% endblock %}
 
 {% block body_attrs %} data-authenticated="true"{% endblock %}

src/lembas/web/templates/settings.html

@@ -4,8 +4,8 @@
 {% block title %}Your settings - {{ brand.name }}{% endblock %}
 
 {% block head %}
-<link rel="stylesheet" href="{{ url_for('static', path='css/chat.css') }}">
-<link rel="stylesheet" href="{{ url_for('static', path='css/admin.css') }}">
+<link rel="stylesheet" href="{{ asset('css/chat.css') }}">
+<link rel="stylesheet" href="{{ asset('css/admin.css') }}">
 {% endblock %}
 
 {% block body_attrs %} data-authenticated="true"{% endblock %}

src/lembas/web/templating.py

@@ -61,6 +61,34 @@ templates.env.filters["tokens"] = highlight_tokens
 templates.env.globals["tool_label"] = tool_labels.label_for
 templates.env.globals["tool_icon"] = tool_labels.icon_for
 
+def asset(path: str) -> str:
+    """A static asset's URL, with the release stamped into it.
+
+    🚨 This is not cache politeness, it is what stops a release drawing itself
+    from two versions at once.
+
+    The service worker caches `/static/...` under a cache named for the
+    release, and a *page* is fetched network-first while its assets come from
+    that cache. So the moment the worker stops taking over open tabs the
+    instant it installs -- which it must, or it swaps the stylesheets under
+    somebody mid-reply -- the new HTML and the old CSS are served together and
+    the interface is subtly wrong until the worker is replaced. That shipped in
+    1.1.0: a close button intended for a phone drawer appeared, unstyled, on
+    every desktop, because the markup knew about it and the stylesheet did not.
+
+    A version in the URL settles it without anybody having to be careful: the
+    new HTML asks for a URL the old cache has never heard of, so it goes to the
+    network. The two can no longer disagree, whichever worker is in charge.
+
+    Not a hash of the file: `__version__` is the one thing that already moves
+    with every release, and a hash would mean reading every asset on every
+    render or a build step, and there is deliberately no build step here.
+    """
+    return f"/static/{path.lstrip('/')}?v={__version__}"
+
+
+templates.env.globals["asset"] = asset
+
 # A finished reply as the sequence of steps it was. A global for exactly the
 # reason the two above are, and it is why turning the bubble into a sequence
 # needed no change in `pages.py`, `post_message`, `regenerate` or the `done`