feat(player): centre the transport and show the volume inline

Two issues over one bar, because they are one relayout. #42's own
findings say so: giving wa-slider a label grows it 6px to 14px and
moves the transport, which is #23's subject, so doing them in sequence
means measuring the bar twice and throwing the first set away.

The bar was `320px 1fr auto`, so the transport sat in the middle of
what the metadata and the queue button did not use — its centre was
~140px right of the window's at every width. The outer two tracks are
the same expression now, so the middle is centred by construction.

The side width is the metadata's, capped at a quarter of the bar, and
the cap was measured as a regression before it was a decision:
reserving the full `--now-playing-width` on both sides is perfectly
centred and takes the seek bar's track from 257px to 61px at 800px, and
to 0 at 200% text. The control you drag was paying for the symmetry.
With the cap it is 246, which is parity. It is a `min()` rather than a
breakpoint because that variable is user state — the metadata has a
drag handle — and tying both sides to it is also what keeps dragging
meaningful; a plain `1fr … 1fr` centres just as well and silently makes
the handle a no-op.

The volume moved out of `audio-player` into the bar because the
transport column has to hold the transport and nothing else, and it
joins the queue button in one cell rather than a second column, since
the centring compares columns.

It is a slider by default and a popup by setting. The stored flag names
the *popup*, which is this config's polarity rule — the zero value has
to be the intended answer, so an existing config.toml gets the new
default with no migration. Inline, the icon is the mute toggle and is
named after that action rather than the state, because with the slider
beside it there is nothing to disclose; the component tier now covers
both presentations rather than whichever is default.

Three nested rules in this block began with a bare element selector,
which Chrome 120 relaxed and the phone's Chrome 113 **silently drops** —
including the ellipsis on the bar's own title and artist, which has
therefore never truncated on the device. They are `&`-prefixed now.
Filed as #154 for the class and for a check.

`bottom-bar.spec.ts` pins both halves separately on purpose: an
uncapped build is perfectly centred and fails only the seek-bar width,
so a spec asserting centring alone would have passed the regression
above. Both were verified by mutation.

Closes #23
Closes #42

frontend/src/components/audio-player/audio-player.ts

@@ -3,7 +3,6 @@ import { customElement } from 'lit/decorators.js';
 import '@awesome.me/webawesome/dist/components/icon/icon.js';
 import './controls/player-controls';
 import './seekbar/seek-bar';
-import './volume-control/volume-control';
 import '../notifications/inline-notice';
 import { PlayerRegion } from '@store/player-store';
 import { designTokens } from '../../styles/tokens.css';
@@ -30,6 +29,7 @@ export class AudioPlayer extends LitElement {
 
     .player-main {
       flex: 1;
+      min-width: 0;
     }
 
     /* The phone transport (plan 016 B2): the buttons, and nothing
@@ -37,14 +37,17 @@ export class AudioPlayer extends LitElement {
        viewport, not by the host, so this is the component saying what
        it drops at phone width rather than the shell reaching in.
 
-       Volume goes because the hardware keys own it on a phone --
-       Android routes them to the media stream, which is also why
-       mediacontrols' Android handler implements no volume callback.
        The seek bar goes because a 4px-tall target dragged with a thumb
        is not a seek control; seeking belongs to the full-screen
-       now-playing view, which is the next phase. */
+       now-playing view.
+
+       Volume used to go from here too, and now goes from index.css
+       instead: #42 moved the control out of this component and into
+       the bar, so the shell is what can hide it. The reason is
+       unchanged -- the hardware keys own volume on a phone, which is
+       also why mediacontrols' Android handler implements no volume
+       callback. */
     @media (max-width: 599px) {
-      volume-control,
       seek-bar {
         display: none;
       }
@@ -65,7 +68,6 @@ export class AudioPlayer extends LitElement {
             <seek-bar></seek-bar>
           </div>
         </div>
-        <volume-control></volume-control>
       </div>
     `;
   }

frontend/src/components/audio-player/volume-control/volume-control.ts

@@ -4,6 +4,7 @@ import '@awesome.me/webawesome/dist/components/icon/icon.js';
 import '@awesome.me/webawesome/dist/components/slider/slider.js';
 import type WaSlider from '@awesome.me/webawesome/dist/components/slider/slider.js';
 import { PlayerController } from '@store/controllers/player-controller';
+import { volumeStyleStore } from '@store/volume-style-store';
 import { designTokens } from '../../../styles/tokens.css';
 import { waSliderLabel } from '../../../styles/wa-slider-label.css';
 
@@ -22,6 +23,12 @@ export class VolumeControl extends LitElement {
   @state()
   private showSlider = false;
 
+  /** Whether this is the click-to-open popup rather than a slider. */
+  @state()
+  private popup = volumeStyleStore.popup;
+
+  private unsubscribeStyle?: () => void;
+
   // Locally-tracked volume while the user is actively dragging or scrolling.
   // The store's volume only updates once the backend echoes VolumeChanged
   // (which we debounce), so we track intent here for responsive UI and to let
@@ -86,11 +93,31 @@ export class VolumeControl extends LitElement {
       --thumb-height: 16px;
     }
 
-    wa-slider::part(track) {
+    .volume-popup wa-slider::part(track) {
       background: var(--yj-text-primary, white);
       height: 120px;
     }
 
+    /* The inline slider (#42). It is the default now, so the width is
+       a real layout decision rather than a detail: 5em is wide enough
+       to aim at and narrow enough that the bottom bar's *outer*
+       columns stay equal without squeezing the transport — which is
+       the arrangement #23 depends on.
+
+       flex-shrink: 0 for the reason the top bar's children have it
+       (#143): a control that quietly gets narrower under pressure
+       hides the fact that the bar has run out of room. This one stands
+       down at phone width instead, in index.css, where the shell can
+       see the viewport. */
+    .inline-slider {
+      width: 5em;
+      flex-shrink: 0;
+    }
+
+    .inline-slider::part(track) {
+      background: var(--yj-text-primary, white);
+    }
+
     wa-slider::part(indicator) {
       background: var(--yj-accent, yellow);
     }
@@ -122,8 +149,23 @@ export class VolumeControl extends LitElement {
   // LIFECYCLE
   // ===================================================================
 
+  override connectedCallback() {
+    super.connectedCallback();
+
+    this.unsubscribeStyle = volumeStyleStore.subscribe(() => {
+      this.popup = volumeStyleStore.popup;
+
+      // Switching to the slider while the popup is open would leave the
+      // document listener installed for a popup that no longer renders.
+      if (!this.popup) this.closeSlider();
+    });
+
+    void volumeStyleStore.init();
+  }
+
   override disconnectedCallback() {
     super.disconnectedCallback();
+    this.unsubscribeStyle?.();
     document.removeEventListener('click', this.boundHandleOutsideClick);
     clearTimeout(this.volumeDebounceTimer);
   }
@@ -154,10 +196,12 @@ export class VolumeControl extends LitElement {
   private handleOutsideClick(e: Event) {
     const path = e.composedPath();
 
-    if (!path.includes(this)) {
-      this.showSlider = false;
-      document.removeEventListener('click', this.boundHandleOutsideClick);
-    }
+    if (!path.includes(this)) this.closeSlider();
+  }
+
+  private closeSlider() {
+    this.showSlider = false;
+    document.removeEventListener('click', this.boundHandleOutsideClick);
   }
 
   private handleInput(e: Event) {
@@ -192,18 +236,46 @@ export class VolumeControl extends LitElement {
   override render() {
     const muted = this.player.muted;
 
+    // Inline, the icon is the mute toggle rather than a disclosure:
+    // there is nothing left to disclose, and a button that opens a
+    // popup containing the slider already beside it would be a control
+    // whose only effect is to duplicate its neighbour.
+    const iconAction = this.popup
+      ? this.toggleSlider
+      : () => this.player.toggleMute();
+    const iconLabel = this.popup
+      ? muted
+        ? 'Muted'
+        : `Volume ${this.currentVolume}%`
+      : muted
+        ? 'Unmute'
+        : 'Mute';
+
     return html`
       <button
         class=${muted ? 'muted' : ''}
         title=${muted ? 'Muted — click for volume' : 'Volume'}
-        aria-label=${muted ? 'Muted' : `Volume ${this.currentVolume}%`}
+        aria-label=${iconLabel}
         data-muted=${muted ? 'true' : 'false'}
-        @click="${this.toggleSlider}"
+        @click="${iconAction}"
         @wheel="${this.handleWheel}"
       >
         <wa-icon name=${this.volumeIcon}></wa-icon>
       </button>
-      ${this.showSlider
+      ${!this.popup
+        ? html`
+            <wa-slider
+              class="inline-slider ${muted ? 'muted' : ''}"
+              label="Volume"
+              min="0"
+              max="100"
+              .value="${this.currentVolume}"
+              @input="${this.handleInput}"
+              @wheel="${this.handleWheel}"
+            ></wa-slider>
+          `
+        : ''}
+      ${this.popup && this.showSlider
         ? html`
             <div
               class="volume-popup ${muted ? 'muted' : ''}"

frontend/src/components/config-page/config-page.ts

@@ -25,6 +25,8 @@ import {
     SetQueueFallback,
     GetAllowMeteredCatalogDownload,
     SetAllowMeteredCatalogDownload,
+    GetPopupVolume,
+    SetPopupVolume,
 } from '@go/config/config.js';
 import { GetIndexStatus } from '@go/explore/service.js';
 import { notificationStore } from '@store/notification-store';
@@ -125,6 +127,8 @@ export class ConfigPage extends ViewLifecycleMixin(LitElement) {
     @state() private concurrencyMode = 'auto';
     @state() private defaultPage = 'home';
     @state() private queueFallback = 'favorites';
+
+    @state() private popupVolume = false;
     @state() private indexStatus: explore.IndexStatus | null = null;
     /** Three states, not one: the panel used to say "Loading status…"
      *  for the entire session, because the only thing that ever set
@@ -938,20 +942,28 @@ export class ConfigPage extends ViewLifecycleMixin(LitElement) {
 
     private async loadLibraries(): Promise<void> {
         try {
-            const [libs, mode, defaultPage, queueFallback, allowMetered] =
-                await Promise.all([
-                    GetAllLibrariesWithTrackCounts(),
-                    GetScanConcurrency(),
-                    GetDefaultPage(),
-                    GetQueueFallback(),
-                    GetAllowMeteredCatalogDownload(),
-                ]);
+            const [
+                libs,
+                mode,
+                defaultPage,
+                queueFallback,
+                allowMetered,
+                popupVolume,
+            ] = await Promise.all([
+                GetAllLibrariesWithTrackCounts(),
+                GetScanConcurrency(),
+                GetDefaultPage(),
+                GetQueueFallback(),
+                GetAllowMeteredCatalogDownload(),
+                GetPopupVolume(),
+            ]);
 
             this.libraries = libs ?? [];
             this.concurrencyMode = mode;
             this.defaultPage = defaultPage;
             this.queueFallback = queueFallback;
             this.allowMeteredCatalogDownload = allowMetered;
+            this.popupVolume = popupVolume;
 
         } catch (err) {
             console.error(
@@ -1858,10 +1870,51 @@ export class ConfigPage extends ViewLifecycleMixin(LitElement) {
                     .value=${this.queueFallback}
                     @config-change=${this.handleQueueFallbackChange}
                 ></config-field>
+                <config-field
+                    .schema=${{
+                        key: 'popupVolume',
+                        label: 'Volume opens in a popup',
+                        description:
+                            'Off, the volume slider is always visible in the '
+                            + 'player bar. On, it hides behind the speaker '
+                            + 'icon. The slider stands down on a phone either '
+                            + 'way, where the hardware keys own volume.',
+                        type: 'toggle' as const,
+                    }}
+                    .value=${this.popupVolume}
+                    @config-change=${this.handlePopupVolumeChange}
+                ></config-field>
             </config-section>
         `;
     }
 
+    /**
+     * The volume control's presentation (#42).
+     *
+     * In General rather than beside the theme because it is about the
+     * transport's behaviour rather than its colours, and next to "When
+     * the Queue Ends" because both are answers to "how should the
+     * player behave".
+     */
+    private handlePopupVolumeChange = (
+        e: CustomEvent<ConfigFieldChangeEvent>,
+    ): void => {
+        const popup = Boolean(e.detail.value);
+        const previous = this.popupVolume;
+
+        this.popupVolume = popup;
+
+        void SetPopupVolume(popup).catch((err: unknown) => {
+            console.error('failed to save the volume control setting', err);
+            this.popupVolume = previous;
+            notificationStore.transient({
+                key: 'popup-volume-setting',
+                title: 'Setting not saved',
+                text: describeError(err, 'That setting could not be saved.'),
+            });
+        });
+    };
+
     // --- Navigation section ---
 
     /**

frontend/src/store/volume-style-store.ts

@@ -0,0 +1,85 @@
+import { EventsOn } from '@runtime/runtime';
+import { GetPopupVolume } from '@go/config/config.js';
+import { Events } from '../events';
+
+type Subscriber = () => void;
+
+/**
+ * Whether the volume control is a click-to-open popup (#42).
+ *
+ * The popup was the only option, and "click open, drag, click closed"
+ * is three gestures for a control a bottom bar has room to just show.
+ * So an inline slider is the default and the popup is a setting.
+ *
+ * **The stored flag names the popup, not the slider**, which is the
+ * polarity rule `backend/config` states for every option it has: the
+ * zero value has to be the intended answer. An `InlineVolume bool`
+ * would default to false, hand the popup to every existing install, and
+ * need a migration to say what the default already says.
+ *
+ * It is a store rather than a field on the component because two
+ * components render `<volume-control>` — the bottom bar and the phone's
+ * full-screen now-playing view — and a setting that only reached
+ * whichever one happened to mount after it changed is the fault
+ * `active-view-store` exists to prevent, one surface over.
+ *
+ * The initial value is the *default* rather than a pending answer, so
+ * the first paint is the inline slider and not an empty gap that
+ * becomes one. An install that has chosen the popup sees it swap once
+ * on load, which is the cheaper of the two wrong first frames: the
+ * inline slider occupies the space the popup's button would have.
+ */
+class VolumeStyleStore {
+    private value = false;
+
+    private loaded = false;
+
+    private subscribers = new Set<Subscriber>();
+
+    constructor() {
+        EventsOn(Events.GeneralConfigChanged, () => {
+            void this.refresh();
+        });
+    }
+
+    /** Whether to draw the popup. Safe to read before `init()`. */
+    get popup(): boolean {
+        return this.value;
+    }
+
+    /** Reads the setting once. Safe to call from every mount. */
+    async init(): Promise<void> {
+        if (this.loaded) return;
+
+        this.loaded = true;
+
+        await this.refresh();
+    }
+
+    subscribe(fn: Subscriber): () => void {
+        this.subscribers.add(fn);
+
+        return () => this.subscribers.delete(fn);
+    }
+
+    private async refresh(): Promise<void> {
+        try {
+            const popup = await GetPopupVolume();
+
+            if (popup === this.value) return;
+
+            this.value = popup;
+            this.notify();
+        } catch (err) {
+            // Nothing to tell the user: the control renders in its
+            // default presentation, which is a working volume control.
+            console.error('failed to read the volume control setting', err);
+        }
+    }
+
+    private notify(): void {
+        for (const fn of this.subscribers) fn();
+    }
+}
+
+export const volumeStyleStore = new VolumeStyleStore();