A tab bar's edge fade that stays hidden until something is off the edge

The local-attached covers were as wide as the scroll shadows and solid for
only 40% of that, so most of each shadow showed at rest -- invisible on Moria,
a grey sliver at both ends of every tab bar on Shire. The covers are now twice
the shadow's width and solid across all of it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -16,6 +16,60 @@ for 1.0.0 have something to be assembled from.
 
 ## Unreleased
 
+## 1.8.5
+
+- **No more grey slivers at the ends of the tab bars.** Tab bars fade at an edge
+  to show there are more tabs to scroll to. The fade was only partly hidden
+  when there was nothing to scroll, so a shadow always showed at both ends. It
+  was invisible on the dark theme and a grey sliver on Shire, on Administration
+  → Prompts, Settings and every other tabbed page. The fade now appears only
+  on the side where tabs are actually hidden.
+
+## 1.8.4
+
+Two things that kept showing up after they should have gone away.
+
+- **"A new version is ready" no longer appears on a page that is already the
+  new version.** After an update the toast showed up on every page, even one just
+  fetched with Ctrl+Shift+R, and reloading never made it go away. It fired
+  whenever a new service worker was waiting. But a page loaded after the update
+  already *is* the update: pages always come from the server, and every
+  stylesheet and script they name carries the release in its address. The
+  worker that waits is nearly always the one from the previous release, still
+  holding the tab, because a reload opens the new page before the old one goes
+  away. The toast now compares the waiting worker's release with the page's
+  own, so it only appears in a tab that was opened before the update. For the
+  same reason, pressing Reload in one tab no longer reloads the other tabs that
+  are already up to date. That matters when one of them has a reply streaming
+  into it.
+
+- **Switching tabs on Administration → Prompts no longer lifts the page.**
+  Choosing any tab but the first pushed the whole window up by the height of
+  the title bar and left a blank strip along the bottom, under the sidebar too.
+  The prompt cards' hidden labels were positioned against the page instead of
+  the panel. That made the page 6,771px tall behind a window that cannot scroll
+  by hand, and the tab switch then scrolled it anyway. Every scrolling area now
+  contains what is inside it, and a tab switch moves only the panel that
+  scrolls. Administration → General on a small phone had the same leak and is
+  fixed with it.
+
+## 1.8.3
+
+The model picker on a phone, which could not be read once a chat was open.
+
+- **The model menu no longer runs off the left of the screen.** Inside a chat
+  the picker sits in the middle of the top bar, with the panel buttons to its
+  right, and its menu opened from the picker's right edge — so on a phone most
+  of it was off the screen and every model's name was cut off. On a narrow
+  screen the menu now hangs from the bar itself, edge to edge, and every name is
+  whole. Wider screens are unchanged.
+
+- **Opening it on a touchscreen no longer raises the keyboard.** With more than
+  eight models the menu has a filter box, and it took the focus on opening — so
+  the keyboard came up and covered half the list you had opened it to choose
+  from. On a touchscreen the chosen model takes the focus instead; the filter is
+  one tap away. With a mouse, typing straight into the filter works as before.
+
 ## 1.8.2
 
 The model lists, made readable. Both printed every capability switch as a tag —

src/lembas/__init__.py

@@ -1,3 +1,3 @@
 """LLeMbas - a Middle-earth themed web UI for OpenAI-compatible LLM endpoints."""
 
-__version__ = "1.8.2"
+__version__ = "1.8.5"

src/lembas/web/static/css/admin.css

@@ -167,16 +167,24 @@ a.tabs__tab { text-decoration: none; }
   pinned to the scrollport with `background-attachment: local`, which is the old
   trick and works everywhere -- the `local` layers scroll with the content and
   cover the `scroll` ones exactly when there is nothing more to see.
+
+  ⚠ "Cover" has to mean all of it. The covers used to be as wide as the
+  shadows and solid for only 40% of that width, so the other 60% of every
+  shadow always showed through, with nothing to scroll to. On Moria that is
+  near-black on near-black and nobody saw it. On Shire it was a grey sliver at
+  both ends of every tab bar. Each cover is now twice the shadow's width and
+  solid across the first half, which is the whole shadow. It fades only past
+  the shadow's end, so once content is scrolled the shadow shows as before.
 */
 .tabs__bar {
   background-image:
-    linear-gradient(to right, var(--bg) 40%, transparent),
+    linear-gradient(to right, var(--bg) 50%, transparent),
-    linear-gradient(to left, var(--bg) 40%, transparent),
+    linear-gradient(to left, var(--bg) 50%, transparent),
     linear-gradient(to right, var(--scrim), transparent 1.5rem),
     linear-gradient(to left, var(--scrim), transparent 1.5rem);
   background-position: left center, right center, left center, right center;
   background-repeat: no-repeat;
-  background-size: 1.5rem 100%;
+  background-size: 3rem 100%, 3rem 100%, 1.5rem 100%, 1.5rem 100%;
   background-attachment: local, local, scroll, scroll;
   /* A tab is a destination, so a flick should land on one rather than between
      two. */

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

@@ -452,7 +452,17 @@ input.visually-hidden[type="checkbox"] {
    child will not shrink below its content without it, so a scroller missing it
    grows its parent instead of scrolling inside it. `.thread-scroll` relied on a
    scroll container's automatic minimum size to get away with omitting it, which
-   is true and is not something the next person should have to know. */
+   is true and is not something the next person should have to know.
+
+   `position: relative` makes each scroller the containing block for what is in
+   it, and without it a `.visually-hidden` label is not in it at all. That class
+   is `position: absolute`, so with no positioned ancestor it is placed against
+   the *page*, at its static position -- six thousand pixels down the Tools
+   panel on /admin/prompts -- and the document grew to 6771px behind a root
+   that is `overflow: hidden`. Nobody can scroll that by hand, but
+   `scrollIntoView()` and `focus()` scroll every ancestor that can scroll,
+   and the root can. Switching a tab there lifted the whole shell 56px: the
+   topbar gone off the top and a strip of bare background under everything. */
 .scroll-region,
 .sidebar__scroll,
 .inspector__body,
@@ -460,6 +470,7 @@ input.visually-hidden[type="checkbox"] {
 .thread-scroll,
 .admin-scroll,
 .main > .tabs > .tabs__body {
+  position: relative;
   flex: 1;
   min-height: 0;
   overflow-y: auto;
@@ -1377,6 +1388,23 @@ body.is-resizing .canvas__body { pointer-events: none; }
      which nothing else on the screen tells you -- gets the room back. */
   .topbar__actions .picker__label { display: none; }
 
+  /* And the menu is the bar's, not the picker's. Anchored to the picker it
+     opens `right: 0` of a button that sits mid-bar with the panel buttons to
+     its right, so a 24rem menu ran off the left edge of a 390px phone and cut
+     every name in half. Taking `position` off the picker makes the bar the
+     containing block: the menu spans the bar under it, whatever sits where --
+     up to its usual 24rem, held at the bar's right edge by the auto margin. */
+  .topbar { position: relative; }
+  .topbar__actions .picker { position: static; }
+  .topbar__actions .picker__menu {
+    left: max(var(--sp-2), var(--safe-left));
+    right: max(var(--sp-2), var(--safe-right));
+    width: auto;
+    max-width: 24rem;
+    margin-left: auto;
+  }
+  .topbar__actions .picker__list { max-height: min(22rem, 60dvh); }
+
   .sidebar {
     position: fixed;
     inset: 0 auto 0 0;

src/lembas/web/static/js/app.js

@@ -1099,27 +1099,59 @@
      The worker no longer takes over open pages on its own -- see sw.js -- so
      something has to say that one is waiting, and the reader decides. A toast
      rather than a reload: an application with a reply streaming into it must
-     not be navigated out from under somebody. */
+     not be navigated out from under somebody.
-  function watchForUpdate(registration) {
+
-    function offer(worker) {
+     🚨 "A worker is waiting" is not the same as "this page is out of date",
-      if (!worker || !navigator.serviceWorker.controller) return;
+     and the toast used to treat them as one. After a release it offered a
-      worker.addEventListener("statechange", function () {
+     reload on every page, including one just fetched with Ctrl+Shift+R, and
-        if (worker.state !== "installed") return;
+     reloading could not make it stop. A page is always fetched from the network
+     and every asset it names carries `?v=<release>`, so a page loaded after
+     the update IS the update, whichever worker happens to control it. And the
+     worker that controls it is nearly always the previous one: a reload
+     creates the new page before the old one goes away, so the old worker
+     never runs out of pages and the new one never stops waiting.
+
+     So the question is asked of the page. The worker's release is in its own
+     script URL (`/sw.js?v=`), and the page's is `window.lembasRelease` from
+     base.html. When the two match there is nothing newer to reload into, and
+     the worker is left to take over once the old tabs are closed. */
+  var PAGE_RELEASE = window.lembasRelease || "";
+
+  function releaseOf(worker) {
+    try {
+      return new URL(worker.scriptURL).searchParams.get("v") || "";
+    } catch (error) {
+      return "";
+    }
+  }
+
+  /* Unknown on either side counts as newer: better an extra offer than a
+     release nobody is told about. */
+  function isNewerThanThisPage(worker) {
+    var release = releaseOf(worker);
+    return !PAGE_RELEASE || !release || release !== PAGE_RELEASE;
+  }
+
+  function offerReload(worker) {
     window.lembas.notify(
       "A new version is ready. Reload to use it.",
       { kind: "info", action: { label: "Reload", run: function () {
         worker.postMessage({ type: "SKIP_WAITING" });
       } } }
     );
+  }
+
+  function watchForUpdate(registration) {
+    function offer(worker) {
+      if (!worker || !navigator.serviceWorker.controller) return;
+      worker.addEventListener("statechange", function () {
+        if (worker.state !== "installed") return;
+        if (isNewerThanThisPage(worker)) offerReload(worker);
       });
     }
-    if (registration.waiting && navigator.serviceWorker.controller) {
+    if (registration.waiting && navigator.serviceWorker.controller &&
-      window.lembas.notify(
+        isNewerThanThisPage(registration.waiting)) {
-        "A new version is ready. Reload to use it.",
+      offerReload(registration.waiting);
-        { kind: "info", action: { label: "Reload", run: function () {
-          registration.waiting.postMessage({ type: "SKIP_WAITING" });
-        } } }
-      );
     }
     registration.addEventListener("updatefound", function () {
       offer(registration.installing);
@@ -1130,17 +1162,24 @@
      the right answer to it -- the page is now being served by a worker whose
      cache it did not start from.
 
-     Two guards, and the second is the one that is easy to miss. A flag, because
+     Three guards, and the second is the one that is easy to miss. A flag,
-     `controllerchange` can fire more than once. And `hadController`, because on
+     because `controllerchange` can fire more than once. And `hadController`,
-     a *first* visit there is no worker at all: the one that installs then calls
+     because on a *first* visit there is no worker at all: the one that
-     `clients.claim()`, which fires this event for the first time -- so without
+     installs then calls `clients.claim()`, which fires this event for the
-     it, the very first page anybody loads reloads itself in front of them for
+     first time -- so without it, the very first page anybody loads reloads
-     no reason they could possibly work out. */
+     itself in front of them for no reason they could possibly work out.
+
+     The third is the same question as the toast's. Somebody pressing Reload in
+     one tab activates the worker for all of them, and a tab that was already
+     rendered by that release has nothing to gain from a reload -- and may have
+     a reply streaming into it. */
   var reloading = false;
   if ("serviceWorker" in navigator) {
     var hadController = !!navigator.serviceWorker.controller;
     navigator.serviceWorker.addEventListener("controllerchange", function () {
       if (reloading || !hadController) return;
+      var controller = navigator.serviceWorker.controller;
+      if (controller && !isNewerThanThisPage(controller)) return;
       reloading = true;
       window.location.reload();
     });

src/lembas/web/static/js/ui.js

@@ -320,6 +320,11 @@
     if (filter) {
       filter.value = "";
       applyFilter(menu, "");
+    }
+    // Not on a touchscreen: focusing a text field there raises the keyboard,
+    // which covers half the list the finger came to choose from. The filter
+    // is one tap away for whoever wants it.
+    if (filter && !window.matchMedia("(hover: none)").matches) {
       filter.focus();
     } else {
       var selected = menu.querySelector(".picker__option.is-selected") ||
@@ -1128,7 +1133,19 @@ document.addEventListener("lembas:notify", function (event) {
        shrinks the document and scrollTop is clamped to the new maximum, which
        for a short panel is somewhere below everything. */
     var outer = scroller(bar);
-    if (outer && outer !== body) bar.scrollIntoView({ block: "start" });
+    if (!outer || outer === body) return;
+    /* Moved by hand, and only `outer`. `scrollIntoView` scrolls *every*
+       ancestor that can scroll, the document included -- and the document
+       could, by the height of whatever leaked out of the scroller, so a tab
+       switch lifted the whole shell and left a strip of background under it.
+       The containing block in app.css stops the leak; this stops a leak
+       anyone adds later from being turned into a visible one.
+
+       Measured from `.tabs`, not the bar: the bar is sticky, so once the page
+       is scrolled past the lede it reports the scroller's own top and the
+       sum below would come out as nothing to do. */
+    var tabs = bar.parentElement;
+    outer.scrollTop += tabs.getBoundingClientRect().top - outer.getBoundingClientRect().top;
   });
 })();
 

src/lembas/web/templates/base.html

@@ -152,6 +152,9 @@
   what `app.js` turns into a sentence on the settings page.
 #}
 <script>
+  /* The release this page was rendered by, for `app.js` to hold a waiting
+     worker up against -- see "A release that arrived while you were reading". */
+  window.lembasRelease = {{ version | tojson }};
   window.lembasWorker = { state: "unsupported" };
   if (!window.isSecureContext) {
     /* Reported separately from an outright failure: the fix is different. */

tests/test_layout_bounds.py

@@ -208,3 +208,19 @@ def test_the_desktop_minimum_is_still_declared():
     for token in ("--terminal-width-min", "--canvas-width-min"):
         assert f"{token}:" in TOKENS
         assert f"var({token})" in APP_CSS
+
+
+def test_the_topbar_model_menu_belongs_to_the_bar_on_a_phone():
+    """1.8.3. Anchored to the picker, the menu opened `right: 0` of a button that
+    sits mid-bar with the panel buttons to its right, so on a 390px phone a 24rem
+    menu started 132px left of the screen and every model's name was cut off.
+
+    Below the phone breakpoint the picker gives up `position`, which makes the bar
+    the containing block, and the menu is pinned between the bar's two edges."""
+    body = _media_body(APP_CSS, "48rem")
+    assert re.search(r"\.topbar\s*\{\s*position:\s*relative", body)
+    assert re.search(r"\.topbar__actions \.picker\s*\{\s*position:\s*static", body)
+    menu = re.search(r"\.topbar__actions \.picker__menu\s*\{([^}]*)\}", body)
+    assert menu, "the topbar's menu is not placed on a phone"
+    for declaration in ("left:", "right:", "width: auto"):
+        assert declaration in menu.group(1), f"{declaration} missing from the phone menu"

tests/test_model_lists.py

@@ -111,3 +111,22 @@ def test_settings_lists_the_models_with_their_tags_below_the_name(client, models
     assert listing.count("#i-eye") == 1
     assert listing.count('class="model-list__more model-list__tags"') == 2
     assert "tool_fetch" in listing
+
+
+def test_opening_the_picker_on_a_touchscreen_does_not_raise_the_keyboard():
+    """1.8.3. With more than eight models the menu has a filter, and `open()`
+    focused it -- which on a phone raises the keyboard over half the list the
+    finger came to choose from. The focus is gated on `(hover: none)`, the same
+    query the stylesheet uses for touch."""
+    from pathlib import Path
+
+    import lembas
+
+    js = (Path(lembas.__file__).parent / "web/static/js/ui.js").read_text(encoding="utf-8")
+    start = js.index("function open(picker)")
+    body = js[start : js.index("function applyFilter", start)]
+    assert "filter.focus()" in body, "the filter is no longer focused anywhere -- test is blind"
+    gated = r'if \(filter && !window\.matchMedia\("\(hover: none\)"\)\.matches\)\s*\{'
+    assert re.search(gated + r"\s*filter\.focus\(\)", body), (
+        "the filter is focused on open without asking whether this is a touchscreen"
+    )

tests/test_pwa.py

@@ -311,3 +311,33 @@ def test_the_worker_precaches_what_a_page_will_ask_for():
     source = (STATIC_DIR / "js" / "sw.js").read_text()
     assert 'path + "?v=" + VERSION' in source
     assert "versioned(path)" in source
+
+
+def test_the_update_offer_asks_whether_this_page_is_older(client: TestClient, registered):
+    """After a release the toast offered a reload on every page, including one
+    just fetched with Ctrl+Shift+R, and reloading never made it go away. It
+    fired whenever a worker was waiting. But a page loaded after the update
+    already IS the update: it comes from the network, and every asset it names
+    carries `?v=`. The worker that waits is nearly always the previous one,
+    still holding the tab, because a reload never lets it run out of pages.
+
+    So the offer, and the automatic reload when another tab accepts it, compare
+    the worker's release with the page's own. Driven under Node against stubs
+    before committing: 1.8.3 offered a reload to a current page and to a page
+    that another tab's Reload had just made current. This does neither, and
+    still offers it to a page from an older release.
+    """
+    import re
+
+    import lembas
+
+    page = client.get("/chat").text
+    assert f"window.lembasRelease = \"{lembas.__version__}\";" in page
+
+    source = (STATIC_DIR / "js" / "app.js").read_text()
+    code = re.sub(r"/\*.*?\*/", "", source, flags=re.S)
+    start = code.index("function watchForUpdate")
+    block = code[start : code.index("navigator.serviceWorker.ready.then(watchForUpdate)")]
+    # Both ways a waiting worker is found, and the controllerchange reload.
+    assert block.count("isNewerThanThisPage(") == 3
+    assert 'searchParams.get("v")' in code

tests/test_ui_js.py

@@ -177,6 +177,48 @@ def test_the_tab_reset_finds_the_container_that_actually_scrolls():
     assert "scrollHeight > " in SOURCE
 
 
+def test_a_tab_switch_moves_only_the_container_that_scrolls():
+    """Switching a tab on /admin/prompts lifted the whole shell 56px, with the
+    topbar gone off the top and a strip of bare background under everything.
+
+    Two halves, and either one alone is enough to bring it back. The prompt
+    cards' `.visually-hidden` labels are `position: absolute`. With no
+    positioned ancestor they were placed against the page and stretched the
+    document to 6771px behind an `overflow: hidden` root. And the handler used
+    `scrollIntoView`, which scrolls every ancestor that can scroll, the root
+    included. Measured in headless Chromium at 1640x930 before and after.
+    """
+    app = (ROOT / "web/static/css/app.css").read_text(encoding="utf-8")
+    start = app.index(".scroll-region,")
+    rule = app[start : app.index("}", start)]
+    assert ".admin-scroll" in rule
+    assert "position: relative" in rule
+
+    code = re.sub(r"/\*.*?\*/", "", SOURCE, flags=re.S)
+    start = code.index('closest(".tabs__bar")')
+    handler = code[start : code.index("})();", start)]
+    assert "scrollIntoView" not in handler
+    assert "outer.scrollTop" in handler
+
+
+def test_the_tab_bar_edge_fade_is_covered_when_nothing_overflows():
+    """The covers were as wide as the shadows and solid for only 40% of that,
+    so 60% of each shadow showed through with nothing to scroll to. On Shire
+    that was a grey sliver at both ends of every tab bar. A cover has to be
+    solid across the whole shadow. Measured in headless Chromium on
+    /admin/prompts and /settings in both themes before and after.
+    """
+    admin = (ROOT / "web/static/css/admin.css").read_text(encoding="utf-8")
+    start = admin.index("background-attachment: local, local, scroll, scroll")
+    block = admin[admin.rindex(".tabs__bar {", 0, start) : start]
+    cover = re.search(r"linear-gradient\(to right, var\(--bg\) (\d+)%, transparent\)", block)
+    shadow = re.search(r"var\(--scrim\), transparent ([\d.]+)rem", block)
+    sizes = re.search(r"background-size: ([\d.]+)rem 100%, [\d.]+rem 100%, ([\d.]+)rem 100%", block)
+    assert cover and shadow and sizes, "the edge-fade rule changed shape; re-check it by eye"
+    solid = float(sizes.group(1)) * int(cover.group(1)) / 100
+    assert solid >= float(shadow.group(1)) == float(sizes.group(2))
+
+
 def test_the_two_ends_of_the_shell_stay_level():
     """The sidebar footer and the composer sit either side of the same vertical
     edge and are both content-sized, so without a common floor they end at