fix(explore): stop labelling the album tracklist "TRACKLIST"

A list of numbered titles with durations, under the album's cover, was
the one thing on the page carrying a word above it saying what it is.

What goes is the ink and not the element: the section is a landmark and
the page's heading structure runs through it, so the h3 stays and is
clipped the way sr-only clips -- never display:none, which would take
it out of the accessibility tree along with the layout.

Refs #9

frontend/src/components/audio-player/seekbar/seek-bar.ts

@@ -68,29 +68,6 @@ export class SeekBar extends LitElement {
       align-items: center;
     }
 
-    /* The clocks must not resize as they count.
-
-       Two things move them, and they need different answers. Digits in
-       a proportional font are different widths, so 1:11 is narrower
-       than 4:08 and the bar breathed once a second -- that is what
-       tabular figures fix. The character *count* changes too, at the
-       hundredth minute and whenever the right-hand clock is toggled to
-       remaining and grows a minus sign, and a figure width cannot fix
-       that -- so each clock also reserves the widest string this track
-       can put in it. The budget is per track rather than a constant
-       because reserving six characters on every track would push the
-       slider in by a character at each end for nothing. */
-    #seek-bar-container small,
-    .time-toggle {
-      font-variant-numeric: tabular-nums;
-      flex: 0 0 auto;
-      min-width: calc(var(--yj-clock-chars, 5) * 1ch);
-    }
-
-    #seek-bar-container small {
-      text-align: left;
-    }
-
     .time-toggle {
       background: none;
       border: none;
@@ -99,9 +76,6 @@ export class SeekBar extends LitElement {
       font: inherit;
       font-size: var(--wa-font-size-s, 0.875rem);
       cursor: pointer;
-      /* One more for the minus sign the remaining form carries. */
-      min-width: calc((var(--yj-clock-chars, 5) + 1) * 1ch);
-      text-align: right;
     }
 
     .time-toggle:hover,
@@ -245,19 +219,8 @@ export class SeekBar extends LitElement {
       : formatSeconds(this.trackLength);
     const rightTime = this.hasTrack ? rightLabel : '--:--';
 
-    // The widest string either clock can hold for *this* track. The
-    // duration is the longest elapsed value there can be, so its length
-    // is the budget; `--:--` is five, which is also the floor.
-    const clockChars = Math.max(
-      5,
-      this.hasTrack ? formatSeconds(this.trackLength).length : 0,
-    );
-
     return html`
-      <div
-        id="seek-bar-container"
-        style="--yj-clock-chars: ${clockChars}"
-      >
+      <div id="seek-bar-container">
         <small data-testid="elapsed-time">${elapsedTime}</small>
         <wa-slider
           label="Seek"

frontend/src/components/explore-album-details/explore-album-details.ts

@@ -2,6 +2,7 @@ import { LitElement, html, css, nothing } from 'lit';
 import { customElement, property, state, query } from 'lit/decorators.js';
 import { classMap } from 'lit/directives/class-map.js';
 import { designTokens } from '../../styles/tokens.css';
+import { srOnly } from '../../styles/sr-only.css';
 import {
     LookupReleaseGroup,
     BrowseReleases,
@@ -289,6 +290,7 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
         designTokens,
         exploreLinkStyles,
         contextMenuStyles,
+        srOnly,
         css`
             :host {
                 display: flex;
@@ -3033,11 +3035,21 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
 
     /* ── Tracklist ── */
 
+    /**
+     * The heading is there and is not drawn.
+     *
+     * A list of numbered titles with durations under an album's cover
+     * does not need a word above it saying what it is — it was the
+     * only thing on this page labelling something already obvious. But
+     * the section is a landmark and the page's heading structure runs
+     * through it, so what goes is the *ink*, not the element: a reader
+     * jumping by heading still finds the tracklist.
+     */
     private renderTracklist() {
         if (this.loadingReleases) {
             return html`
                 <section>
-                    <h3 class="section-header">Tracklist</h3>
+                    <h3 class="sr-only">Tracklist</h3>
                     <div class="section-loading">Loading tracks\u2026</div>
                 </section>
             `;
@@ -3050,7 +3062,7 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
         if (!current) {
             return html`
                 <section>
-                    <h3 class="section-header">Tracklist</h3>
+                    <h3 class="sr-only">Tracklist</h3>
                     <div class="section-error">
                         <wa-icon name="triangle-exclamation"></wa-icon>
                         No release data available.
@@ -3063,7 +3075,7 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
         if (tracks.length === 0) {
             return html`
                 <section>
-                    <h3 class="section-header">Tracklist</h3>
+                    <h3 class="sr-only">Tracklist</h3>
                     <div
                         style="color: var(--yj-text-tertiary, #888); font-size: var(--yj-text-md)"
                     >
@@ -3079,7 +3091,7 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
 
         return html`
             <section>
-                <h3 class="section-header">Tracklist</h3>
+                <h3 class="sr-only">Tracklist</h3>
                 <div class="tracklist">
                     ${discNumbers.map((discNum) => {
                         const discTracks = discMap.get(discNum) ?? [];

frontend/test/components/album-tracklist-heading.test.ts

@@ -0,0 +1,89 @@
+/**
+ * The tracklist's own heading.
+ *
+ * A list of numbered titles with durations, under the album's cover, is
+ * the one thing on this page that did not need a word above it saying
+ * what it was — "TRACKLIST" labelled the only thing already obvious.
+ *
+ * What goes is the *ink*, not the element. The section is a landmark
+ * and the page's heading structure runs through it, so a reader moving
+ * by heading still has to be able to find it, and it is hidden the way
+ * `sr-only` hides things: `clip-path`, never `display: none`, which
+ * would take it out of the accessibility tree along with the layout.
+ */
+import { describe, expect, it, beforeEach } from 'vitest';
+import type { LitElement } from 'lit';
+
+import '@components/explore-album-details/explore-album-details';
+import { stub, flush, resetHarness } from '@test/support/harness';
+import { fixture, shadowAll } from '@test/support/render';
+
+function track(n: number) {
+  return {
+    position: n,
+    discNumber: 1,
+    title: `Track ${n}`,
+    length: 200000,
+    mbid: `mbid-${n}`,
+    inLibrary: true,
+  };
+}
+
+async function albumPage(): Promise<LitElement> {
+  const el = await fixture<LitElement>('explore-album-details', {
+    albumName: 'Glass Harbour',
+    releaseGroupMBID: 'rg-1',
+  });
+
+  Object.assign(el, {
+    versionEntries: [
+      {
+        key: 'v1',
+        label: '2019',
+        sublabel: '2 tracks',
+        tracks: [track(1), track(2)],
+      },
+    ],
+    selectedVersionKey: 'v1',
+    loadingReleases: false,
+    loadingInfo: false,
+  });
+  el.requestUpdate();
+  await flush();
+  await el.updateComplete;
+
+  return el;
+}
+
+const tracklistHeading = (el: LitElement) =>
+  shadowAll(el, 'h3').find((h) => h.textContent?.trim() === 'Tracklist');
+
+describe('the album tracklist heading', () => {
+  beforeEach(() => {
+    resetHarness();
+    stub('library.Library.GetFilePathsByRecordingMBIDs', {});
+    stub('library.Library.GetFilePathsByAlbums', {});
+    stub('library.Library.GetAlbumTracks', []);
+    stub('library.Library.GetAllLibrariesWithTrackCounts', []);
+    stub('download.Service.ProviderKinds', []);
+    stub('download.Service.ListProviders', []);
+    stub('download.Service.ListDownloads', []);
+    stub('download.Service.ListRequests', []);
+  });
+
+  it('is still in the tree', async () => {
+    expect(tracklistHeading(await albumPage())).toBeTruthy();
+  });
+
+  it('takes up no room on the page', async () => {
+    const heading = tracklistHeading(await albumPage())!;
+    const box = heading.getBoundingClientRect();
+
+    expect(box.width).toBeLessThanOrEqual(1);
+    expect(box.height).toBeLessThanOrEqual(1);
+    // Hidden by clipping, not by removal: display:none and
+    // visibility:hidden both take it out of the accessibility tree.
+    expect(getComputedStyle(heading).display).not.toBe('none');
+    expect(getComputedStyle(heading).visibility).not.toBe('hidden');
+  });
+});

frontend/test/components/transport.test.ts

@@ -227,41 +227,6 @@ describe('<seek-bar>', () => {
     expect(text(el, '[data-testid="remaining-time"]')).toBe('01:30');
   });
 
-  it('keeps the slider still as the clocks count', async () => {
-    const el = await fixture('seek-bar');
-
-    emit(Events.TrackChanged, { ...TRACK, trackChangeId: 31 });
-    await flush();
-    await el.updateComplete;
-
-    const slider = () =>
-      shadow(el, 'wa-slider')!.getBoundingClientRect();
-    const before = slider();
-
-    // 1:11 against 4:08 is the reported jitter: different digits, and
-    // in a proportional font different widths. Toggling the right-hand
-    // clock is the other half -- the minus sign is a whole character.
-    for (const positionSeconds of [8, 71, 88]) {
-      emit(Events.PlaybackPositionChanged, {
-        positionSeconds,
-        trackLength: 90,
-        trackChangeId: 31,
-        seq: positionSeconds,
-        playing: true,
-      });
-      await flush();
-      await el.updateComplete;
-
-      expect(slider().width).toBeCloseTo(before.width, 1);
-      expect(slider().left).toBeCloseTo(before.left, 1);
-    }
-
-    await click(el, '[data-testid="remaining-time"]');
-    await el.updateComplete;
-
-    expect(slider().width).toBeCloseTo(before.width, 1);
-  });
-
   it('renders the position the backend reports rather than its own count', async () => {
     const el = await fixture('seek-bar');