test(player): assert the desktop bar's size by mechanism, not by pixels

WebKit draws the same button 36x24 where Chromium draws 33x21, so the
literal this pinned failed in CI on a build where nothing was wrong. A
button's box comes from the UA stylesheet when the author sets nothing,
and what each UA sets is its own business.

What must not happen is that *we* set something. So: `min-width` and
`min-height` compute to 0px, the font-size still equals that of a bare
button probed in the same page, and all five boxes are identical --
which is what says the desktop is neither sized context. Checked by
re-introducing the `font-size: inherit` regression, which it catches in
Chromium; the literal form could only be checked by hand.

.planning/NOTES.md

@@ -4429,3 +4429,147 @@ the content starts where the **row above it** ends, which is true with a
 job running and without one. An assertion against an absolute
 coordinate was quietly also asserting "and no background job exists",
 which is not something that spec is about or can arrange.
+
+## The queue was already the right rectangle; what it lacked was an entry (measured 2026-08-21)
+
+#55 asks for the queue to be "a real screen instead of a pop-open
+sidebar", and its Direction asks for a `DETAIL_LOADERS` mount. Measured
+against `880adff` at the reference device's real viewport (424x439),
+with #24's overlay open:
+
+| box | rect |
+|---|---|
+| `.main-panel` | 424 x 318 |
+| `queue-panel` host | 424 x 318 |
+| `.panel-content` | 424 x 318 |
+| `.scrim` | 424 x 318, entirely underneath the panel |
+
+So a detail-view mount would have drawn the same rectangle in the same
+place. Three things were genuinely missing, and none of them is a
+rendering:
+
+- **Back navigated the page underneath and left the queue up.** Opened
+  on Artists, pressed back: `data-active-view` went `artists` ->
+  `albums`, `open` stayed `true`. A press that changes something the
+  user cannot see, and costs them their place.
+- **The scrim has zero reachable pixels at phone width**, because
+  `panel-content` is `width: 100%` there. #24's tap-outside-to-close
+  does not exist on the device.
+- The only pointer route out was a **25x21px** button.
+
+The rule that followed is that the queue is a *place* exactly while it
+is an overlay and a *control* while it is a column, which reuses #24's
+computed mode rather than adding a breakpoint.
+
+**The containment finding is the reason the Direction was not
+followed.** Read off the running app rather than the stylesheet:
+
+| element | computed `contain` |
+|---|---|
+| `queue-panel` (open, overlay) | `layout style` |
+| `.content-area` | `layout style` |
+| `.main-panel` | `content` |
+| `.main-panel > *` (a view) | `content` |
+
+`queue-panel` has a `wa-popup` context menu, and #60's finding is that
+`position: fixed` escapes overflow but not paint containment on
+Chrome 113. Its ancestry today is paint-free to `body`; a
+`DETAIL_LOADERS` mount would have put it under two paint-containing
+ancestors. **No tier here can see that** — CI's Chromium and WebKit
+both have the Popover API — so the spec asserts the mechanism (the
+panel is not under a paint-contained ancestor) rather than the
+symptom. This is the second change in a row where the honest assertion
+was about where an element *is* rather than how it *looks*.
+
+One thing worth knowing about the spec: **three of its nine tests fail
+on the build before the change and the other six cannot.** "The entry
+is not orphaned" and "a docked column is not in the stack" are both
+vacuously true of a build that pushes no entry at all. Reverting the
+source and re-running is what established which were which, and the
+file says so in its header rather than implying all nine reproduce.
+
+## The phone's transport, and three things that only a screenshot or a stash could see (measured 2026-08-21)
+
+#59 and #56 were done as one PR — argued on #73 first — because they are
+the same row of pixels: one removes controls from the phone's bar and
+the other enlarges what is left, and both are one property on
+`player-controls`. Measured at 424x439 before:
+
+| control | before | after |
+|---|---|---|
+| bar: shuffle / prev / play / next / repeat | 33x21 each | prev/next 44, play 56, shuffle+repeat moved |
+| bar: favourite | **18x14** | 44x44 |
+| bar: queue button | 33x29 | gone (#59) |
+| Now Playing: all five | 33x21 each | 44, play 64 |
+| desktop bar: all five | 33x21 | **33x21** |
+
+Four things cost a cycle each and are worth keeping.
+
+**A `<button>` does not inherit its font from its parent.** The UA
+stylesheet gives it one, so `font-size: inherit` on a button is a
+*change*, not a no-op: it took every desktop control from 33x21 to
+36x24 by moving them from 13.3px to the shell's 16px. Nothing failed.
+The only way it surfaced was measuring the baseline by stashing the file
+and re-running.
+
+**And the pixel it was first pinned with was the wrong assertion.** The
+spec asserted the literal `'33x21'`, measured in Chromium — and WebKit
+draws the same button **36x24**, so it failed in CI on a build where
+nothing was wrong. A button's box comes from the UA stylesheet when the
+author sets nothing, and what each UA sets is its own business. What
+must not happen is that *we* set something, so that is what it asserts
+now: `min-width` and `min-height` compute to `0px`, and the font-size
+still equals that of a bare `<button>` probed in the same page. That
+form catches the `font-size: inherit` regression in either engine —
+checked by re-introducing it — and it is the same "assert the
+mechanism" move `queue-as-a-screen.spec.ts` makes about containment.
+
+It is also the second time in two sessions that **CI's WebKit was the
+only tier that could see something**, which is the argument for checking
+that step ran rather than trusting the run's conclusion.
+
+**A rule at the bottom of `index.css` still loses to a nested rule
+above it.** The phone block is last on purpose because a media query
+adds no specificity — but `#queue-button` is written *nested* inside
+`.bottom-bar`, so it builds to a descendant selector one class more
+specific, and a bare `#queue-button { display: none }` in the phone
+block did nothing at all. Silently: the button simply stayed. Nesting
+adds specificity the source does not show.
+
+**Removing a control moved the question of how you reach what is left,
+and ten specs were quietly asserting the old answer.** Hiding the bar's
+queue button failed ten tests in four files about the back stack and
+about layout, every one of which opened the queue by clicking
+`#queue-button`. `openTheQueue` in `e2e/support/fixtures.ts` is the
+route *this viewport* offers, and the fix was to stop hard-coding one.
+
+**And the route it takes did not exist in the state that matters.**
+`now-playing` renders two branches, and the no-track one had no
+`.expand` button — so with nothing loaded there was no way to Now
+Playing, and once the queue button left the bar the queue was
+unreachable outright. The queue is persisted across restarts, so this
+is a state the app launches into, not a corner. It first appeared as a
+*flake* (#168: the long-lived e2e app meant whether a track was loaded
+depended on which spec ran first), which is worth remembering — a leak
+made a deterministic bug look like a race.
+
+## Now Playing does not fit a 439px screen, and #56 makes that visible (measured 2026-08-21)
+
+Two separate things, and only the first is a defect.
+
+**The art overflowed its own box and drew over the header and the
+title.** It is `width: min(100%, 60vh); aspect-ratio: 1`, so its height
+is derived from its width and bounded by nothing — 60vh bounds the
+*viewport*, not the room left over, and those differ by all the chrome
+above and below. `max-height: 100%` is the fix and shipped with #56.
+Pre-existing: screenshotted on `main`. **Found by reading a screenshot,
+which is the only tier that can see it** — nothing fails, the shell does
+not overflow, and every control is still hittable.
+
+**With that fixed, the art is a 39px sliver**, because the transport is
+now 172px of a 439px screen. That is a consequence of #56 rather than a
+fault in it, and it is filed as #172 with the per-element budget. #64
+(no in-app volume on Android) is ~30px of pure gain there and #51 is the
+umbrella; folding shuffle and repeat back onto the primary row was
+considered and rejected — it buys 52px, leaves the art at 91px, and
+costs a third arrangement of the same five buttons.

CLAUDE.md

@@ -1728,6 +1728,55 @@ rather than after the state, because with the slider beside it there is
 nothing left to disclose. It stands down below 600px whatever the
 setting says — that is about the platform rather than preference, and
 is why `mediacontrols`' Android handler implements no volume callback.
+(Only the *bar's* copy: `now-playing-view` renders one and it is
+visible on a phone. #64 asks for it to be gone on Android outright,
+which is a platform question the frontend cannot currently ask.)
+
+**And below 600px that bar carries three controls, not five** (#59).
+Shuffle, repeat and the queue button leave it; what is left is art,
+title/artist, favourite, and prev/play/next. `player-controls` is one
+component in two places and **the context is a property rather than a
+media query**, which is the exception to the rule two paragraphs down:
+on a phone the bar wants three controls and `now-playing-view` wants
+five, larger still, *at the same viewport* — so the host states the
+context and the viewport states the size band, and neither alone can
+express it. Sizes come from `--yj-control-*` custom properties set per
+context; play/pause alone goes above the 44px floor, because a row of
+identical squares says every action is equally likely and that is not
+true of play. Measured before #56: every one of them was **33×21px**,
+and the mini bar's favourite was **18×14**, the smallest control in the
+app.
+
+Four things about it are load-bearing.
+
+**The phone draws three buttons rather than hiding two**, from
+`matchMedia` — `job-band`'s pattern, and the rule that a decision about
+whether an element *exists* is not a stylesheet's to make. A
+`display: none` control is still in the shadow root and still something
+a positional query finds, so "the phone has three controls" would have
+been true of the pixels and false of the element.
+
+**Removing a control is only allowed because it is still reachable.**
+Plan 018's matrix promises no action is unreachable at any supported
+size, and all three are on `now-playing-view`, one tap away through the
+mini player's art. That promise is what `phone-transport.spec.ts`
+asserts — it walks the route — rather than counting buttons.
+
+**So the route to Now Playing must not depend on what is playing**, and
+it did. `now-playing` renders two branches and the no-track one had no
+`.expand` button on its placeholder, so with nothing loaded there was
+no way to the full-screen view — which, once the queue button left the
+bar, made the *queue* unreachable. The queue is persisted across
+restarts, so "tracks queued, nothing playing" is a state the app
+launches into.
+
+**The desktop bar is untouched and a spec says so with a literal.**
+Both issues are `Platform/Android`. The trap is that a `<button>` does
+not inherit its font from its parent — the UA stylesheet gives it one —
+so a generic `font-size: inherit` is not the no-op it reads as: it took
+every desktop button from 33×21 to 36×24, silently. The sizes are
+asserted as `'33x21'` rather than as a range, because the regression
+was three pixels.
 
 **900 is the worst desktop width, not the 800×600 minimum.** The
 sidebar collapses to icons *below* 900, so the main panel is 843px at
@@ -1775,6 +1824,61 @@ along untouched. Escape closes it and returns focus, and is attached
 only while the overlay is up — it is a dismissal, not a shortcut, which
 is why it is not a panel-scoped binding.
 
+**And an overlaid queue is a place, which is the whole of #55.** The
+pixels were already right: measured at the reference device's 424×439,
+the overlaid panel is 424×318 — `.main-panel`'s rect exactly — so a
+`DETAIL_LOADERS` mount would draw the same rectangle in the same spot.
+What was missing was the navigation model, and the defect was one
+measurement: opening the queue on Artists and pressing back moved the
+page *underneath* to Albums and left the queue up. So opening an
+**overlay** queue dispatches `navigate {view: 'queue'}` and opening a
+**column** sets the attribute as it always did — `utils/open-queue.ts`
+is that one decision, and both routes end at the same `open` attribute
+on the same element.
+
+Five things about it are load-bearing.
+
+**The queue is a screen exactly while it is an overlay**, which is the
+rule above rather than a second one: a column is a thing the user
+docked, so back must not undock it and a navigation must not take it
+away, while an overlay is covering the content and has to answer the
+platform's gesture. That also inherits the *computed, not
+breakpointed* property for free — the panel is drag-resizable, so a
+viewport breakpoint would be wrong by up to 180px.
+
+**It is in neither `VIEW_TAGS` nor `DETAIL_LOADERS`**, because there is
+nothing to mount; the panel is already in the document. That is not
+tidiness. `.main-panel > *` is paint-contained under a `.main-panel`
+that is, and `contain: paint` clips the `position: fixed` a `wa-popup`
+falls back to on the reference device's Chrome 113 (#60) — so the
+detail-view mount asked for in #55's Direction would have broken
+`queue-panel`'s working context menu on the one device the issue is
+about. Measured: the panel's ancestry is `layout style` all the way to
+`body`; a view inside the main panel is `content` under `content`.
+**No tier here can see that consequence** — CI's Chromium and WebKit
+both have the Popover API — so `queue-as-a-screen.spec.ts` asserts the
+*mechanism*, that the panel is not under a paint-contained ancestor.
+
+**A navigation to `queue` deliberately writes neither
+`dataset.activeView` nor `searchStore.setCurrentView`**, because both
+describe what is *in* the main panel and the queue covers that panel
+without replacing it. It publishes itself through `activeViewStore`
+with `isPrimary: false`, so the tab it was opened from stays lit —
+the same rule a detail view gets.
+
+**The entry is unwound from the panel's `open` attribute**, in the
+mutation observer `index.ts` already ran for `aria-expanded`, rather
+than at each of the four ways out. Escape, the scrim, the close button
+and the toggle all take that route, and a fifth added later gets it
+free. Without it the entry is orphaned and the *next* back press is the
+one that closes the queue — the reported defect moved one press later,
+which looks exactly like a press that did nothing.
+
+**And the way out is 44px on a phone.** With the panel spanning the
+whole width the scrim has no uncovered pixels at all, so the close
+button is the only pointer route out of a full-screen surface; it was
+**25×21px**.
+
 What this does **not** fix is `page-header` overflowing on its own:
 at 900×600 "New Smart Playlist" is still clipped to 114 of 162px with
 the queue *closed*. That is #69, and it cannot be fixed in

e2e/specs/phone-transport.spec.ts

@@ -0,0 +1,315 @@
+import { test, expect } from '../support/fixtures.js';
+
+/**
+ * The phone's transport (#59, #56).
+ *
+ * #56 reports that "the playback controls are the most important thing
+ * in the mobile app and they are tiny". Measured at the reference
+ * device's 424x439 before this, every one of them was **33x21px**, and
+ * the favourite beside them — which #59 keeps on the bar — was
+ * **18x14px**, the smallest control in the app.
+ *
+ * #59 is what makes the sizes affordable: five controls plus a queue
+ * button at 44px does not fit 424 CSS px, so the bar carries three and
+ * the rest are on the full-screen view.
+ *
+ * **The assertion that matters is not the pixel count.** Plan 018's
+ * matrix promises that *no action is ever unreachable at any supported
+ * size*, and #59 removes three controls from the phone's bar — so the
+ * first thing this file checks is that all three are still reachable,
+ * by walking the route a user would. A spec that only measured the
+ * survivors would be green on a build that had made shuffle
+ * unreachable, which is the failure mode this pair of issues is one
+ * mistake away from.
+ */
+type Page = import('@playwright/test').Page;
+
+/** The reference device's real viewport. */
+const DEVICE = { width: 424, height: 439 };
+const PHONE = { width: 390, height: 780 };
+const DESKTOP = { width: 1280, height: 800 };
+
+/**
+ * The touch-target floor. 44px is what #56's Findings name and what
+ * #55's queue header was sized to, so the app has one number.
+ */
+const TARGET = 44;
+
+/** The play button is named for its action, not its identity. */
+const PLAY_PAUSE = /^(Play|Pause)$/;
+
+const barControls = (page: Page) =>
+  page.locator('audio-player player-controls');
+
+/**
+ * `name` may be a regex, and for play/pause it must be: that button is
+ * named for the *action*, so it is "Pause" while a track runs and
+ * "Play" when it stops. An exact 'Play' made these tests wait out a
+ * fixture track (11.1s each, passing by luck) and would have failed
+ * outright against `LONG_TRACK`. A test about a control's size does not
+ * care what the transport is doing.
+ */
+async function sizeOf(
+  page: Page,
+  name: string | RegExp,
+): Promise<[number, number]> {
+  const box = await page
+    .getByRole('button', { name, exact: typeof name === 'string' })
+    .boundingBox();
+
+  expect(box, `no button named ${name}`).not.toBeNull();
+
+  return [box!.width, box!.height];
+}
+
+/** Put something in the queue, so the transport has a track to act on. */
+async function stageATrack(page: Page): Promise<void> {
+  await page.evaluate(async () => {
+    const tracks = (await window.__yjEvents.call(
+      'library.Library.GetTracks',
+      [0],
+      10_000,
+    )) as { FilePath: string }[];
+
+    await window.__yjEvents.call(
+      'queue.Queue.SetQueue',
+      [tracks.slice(0, 4).map((t) => t.FilePath), 0, false, { type: '', id: 0, label: '' }],
+      10_000,
+    );
+  });
+}
+
+test.describe('the phone bar carries three controls', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(DEVICE);
+    await stageATrack(app);
+  });
+
+  test('drops shuffle, repeat and the queue from the bar', async ({ app }) => {
+    const bar = barControls(app);
+
+    await expect(bar.getByRole('button', { name: 'Previous track' })).toBeVisible();
+    await expect(bar.getByRole('button', { name: 'Next track' })).toBeVisible();
+
+    // Not in the bar's own subtree. Asserted against the bar rather
+    // than the page, because the whole point is that they moved rather
+    // than went away -- a page-wide `not.toBeVisible()` would fail the
+    // moment Now Playing is open and would be asserting the wrong
+    // thing besides.
+    await expect(bar.getByRole('button', { name: 'Shuffle' })).toHaveCount(0);
+    await expect(bar.getByRole('button', { name: /^Repeat/ })).toHaveCount(0);
+    await expect(app.locator('#queue-button')).toBeHidden();
+  });
+
+  /**
+   * The promise, walked. Every control #59 takes off the bar is
+   * reachable from the mini player's art in one tap.
+   */
+  test('leaves every removed control reachable from Now Playing', async ({
+    app,
+  }) => {
+    await app.getByTestId('open-now-playing').click();
+
+    await expect(app.getByTestId('main-content')).toHaveAttribute(
+      'data-active-view',
+      'now-playing',
+    );
+
+    await expect(app.getByRole('button', { name: 'Shuffle' })).toBeVisible();
+    await expect(app.getByRole('button', { name: /^Repeat/ })).toBeVisible();
+    await expect(app.getByRole('button', { name: 'Show the queue' })).toBeVisible();
+  });
+
+  test('sizes what is left for a thumb', async ({ app }) => {
+    for (const name of ['Previous track', 'Next track']) {
+      const [w, h] = await sizeOf(app, name);
+
+      expect(w, `${name} width`).toBeGreaterThanOrEqual(TARGET);
+      expect(h, `${name} height`).toBeGreaterThanOrEqual(TARGET);
+    }
+
+    // Play is deliberately bigger than its neighbours: a row of
+    // identical squares says every action is equally likely, which is
+    // not true of play.
+    const [pw, ph] = await sizeOf(app, PLAY_PAUSE);
+    const [nw] = await sizeOf(app, 'Next track');
+
+    expect(ph).toBeGreaterThanOrEqual(TARGET);
+    expect(pw).toBeGreaterThan(nw);
+  });
+
+  /**
+   * The favourite was 18x14 and is one of the three controls #59
+   * keeps, so it is part of this issue rather than a nicety.
+   */
+  test('sizes the favourite, which was the smallest control in the app', async ({
+    app,
+  }) => {
+    const fav = app
+      .locator('now-playing')
+      .getByRole('button', { name: /Favorites$/ });
+
+    const box = await fav.boundingBox();
+
+    expect(box).not.toBeNull();
+    expect(box!.width).toBeGreaterThanOrEqual(TARGET);
+    expect(box!.height).toBeGreaterThanOrEqual(TARGET);
+  });
+
+  /**
+   * **The route to the queue must not depend on what is playing.**
+   *
+   * `now-playing` renders two branches, and the no-track one had no
+   * `.expand` button on its placeholder — so with nothing loaded there
+   * was no way to Now Playing, and once #59 takes the queue button off
+   * the bar that makes the *queue* unreachable. The queue is persisted
+   * across restarts, so "tracks queued, nothing playing" is a state the
+   * app launches into.
+   *
+   * This is asserted with the queue explicitly emptied rather than by
+   * relying on the app not having played anything: `make e2e` runs one
+   * long-lived app across every spec file (#168), so "no track loaded"
+   * is otherwise whatever the file before this one left behind — which
+   * is how the underlying fault first showed up as a flake in a spec
+   * about something else.
+   */
+  test('reaches the queue with nothing playing', async ({ app }) => {
+    await app.evaluate(async () => {
+      await window.__yjEvents.call('queue.Queue.Clear', [], 10_000);
+    });
+
+    await expect(app.getByTestId('open-now-playing')).toBeVisible();
+
+    await app.getByTestId('open-now-playing').click();
+    await app.getByTestId('npv-queue').click();
+
+    await expect(app.locator('#queue-panel')).toHaveAttribute('open', '');
+  });
+
+  test('still fits, with nothing to scroll sideways to', async ({ app }) => {
+    const fit = await app.evaluate(() => ({
+      scroll: document.body.scrollWidth,
+      client: document.body.clientWidth,
+    }));
+
+    expect(fit.scroll).toBe(fit.client);
+  });
+});
+
+test.describe('the full-screen transport is the page', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(DEVICE);
+    await stageATrack(app);
+    await app.getByTestId('open-now-playing').click();
+  });
+
+  test('draws all five, larger than the bar draws any', async ({ app }) => {
+    const [pw, ph] = await sizeOf(app, PLAY_PAUSE);
+
+    expect(pw).toBeGreaterThanOrEqual(56);
+    expect(ph).toBeGreaterThanOrEqual(56);
+
+    for (const name of ['Shuffle', 'Previous track', 'Next track']) {
+      const [w, h] = await sizeOf(app, name);
+
+      expect(w, `${name} width`).toBeGreaterThanOrEqual(TARGET);
+      expect(h, `${name} height`).toBeGreaterThanOrEqual(TARGET);
+    }
+  });
+
+  test('fits at both phone widths', async ({ app }) => {
+    for (const size of [DEVICE, PHONE]) {
+      await app.setViewportSize(size);
+
+      const fit = await app.evaluate(() => ({
+        scroll: document.body.scrollWidth,
+        client: document.body.clientWidth,
+      }));
+
+      expect(fit.scroll, `${size.width}px`).toBe(fit.client);
+    }
+  });
+});
+
+/**
+ * **The desktop bar is not what either issue is about, and must not
+ * move.** Both are `Platform/Android`; this is the guard that says so
+ * in a way a build can check.
+ *
+ * It caught a real regression while it was being written: a generic
+ * `font-size` on the buttons took them from the UA stylesheet's 13.3px
+ * to the shell's 16px and grew every one from 33x21 to 36x24 — a
+ * change nobody asked for, invisible to every other assertion here.
+ */
+test.describe('the desktop bar is untouched', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(DESKTOP);
+    await stageATrack(app);
+  });
+
+  test('keeps all five controls and the queue button', async ({ app }) => {
+    const bar = barControls(app);
+
+    for (const name of ['Shuffle', 'Previous track', 'Next track']) {
+      await expect(bar.getByRole('button', { name })).toBeVisible();
+    }
+
+    await expect(bar.getByRole('button', { name: /^Repeat/ })).toBeVisible();
+    await expect(app.locator('#queue-button')).toBeVisible();
+  });
+
+  /**
+   * **The mechanism, because the pixels are the engine's.**
+   *
+   * The first version of this asserted the literal `'33x21'`, measured
+   * on `main` in Chromium — and WebKit draws the same button **36x24**,
+   * so it failed in CI on a build where nothing was wrong. A button's
+   * box comes from the UA stylesheet when the author sets nothing, and
+   * what each UA sets is its own business.
+   *
+   * What this PR must not do is *set* anything here, so that is what is
+   * asserted: our two box properties are unset, and the font is still
+   * the UA's rather than the shell's. That is precisely the regression
+   * this caught the first time — a generic `font-size: inherit` took
+   * these from the UA's default to 16px — and it catches it in either
+   * engine.
+   */
+  test('sets no size of its own on the desktop bar', async ({ app }) => {
+    const measured = await barControls(app).evaluate((el) => {
+      // A bare button with no author styles: whatever this engine
+      // gives one is what the bar's buttons must still be.
+      const probe = document.createElement('button');
+
+      document.body.appendChild(probe);
+
+      const uaFontSize = getComputedStyle(probe).fontSize;
+
+      probe.remove();
+
+      return [...el.shadowRoot!.querySelectorAll('button')].map((b) => {
+        const cs = getComputedStyle(b);
+        const r = b.getBoundingClientRect();
+
+        return {
+          minWidth: cs.minWidth,
+          minHeight: cs.minHeight,
+          usesUaFont: cs.fontSize === uaFontSize,
+          size: `${Math.round(r.width)}x${Math.round(r.height)}`,
+        };
+      });
+    });
+
+    expect(measured).toHaveLength(5);
+
+    for (const m of measured) {
+      expect(m.minWidth, 'min-width').toBe('0px');
+      expect(m.minHeight, 'min-height').toBe('0px');
+      expect(m.usesUaFont, 'font-size is still the UA default').toBe(true);
+    }
+
+    // And all five are the same box: `.play` takes a larger size in
+    // both sized contexts, so this is what says the desktop is neither
+    // of them.
+    expect(new Set(measured.map((m) => m.size)).size).toBe(1);
+  });
+});

e2e/specs/queue-as-a-screen.spec.ts

@@ -0,0 +1,346 @@
+import { test, expect, openTheQueue } from '../support/fixtures.js';
+
+/**
+ * #55 — the queue is a *place* while it covers the content, and a
+ * *control* while it sits beside it.
+ *
+ * #24 already made the pixels right: measured at the reference device's
+ * 424×439, the overlaid panel is 424×318, which is `.main-panel`'s rect
+ * exactly. What was missing was the navigation model, and the defect was
+ * measurable in one line — opening the queue on Artists and pressing
+ * back moved the page *underneath* to Albums and left the queue up. A
+ * back press that changes something the user cannot see, and costs them
+ * their place, is the whole of "it does not flow".
+ *
+ * **These assert the entry, not the attribute.** The temptation is to
+ * check `#queue-button[aria-expanded]` and stop, which is the shell's
+ * own bookkeeping and was right throughout the bug: what has to be true
+ * is that *one* back press closes the queue and the *next* one
+ * navigates. Asserting only the first would pass on a build that
+ * orphans the entry, which is the defect moved one press later — the
+ * same trap `back-navigation.spec.ts` documents about `data-active-view`
+ * and `layout-overflow.spec.ts` set for #69.
+ *
+ * **Three of these nine fail on the build before #55**, and the other
+ * six cannot, which is worth knowing before trusting them: "the entry
+ * is not orphaned" and "the column is not in the stack" are both
+ * vacuously true of a build that pushes no entry at all, and the
+ * containment assertion pins the mount that was *not* taken. They guard
+ * the next change rather than reproducing this one — the three that
+ * reproduce it are the two back-press tests and the touch target.
+ */
+type Page = import('@playwright/test').Page;
+
+/** The reference device's real viewport, not a resized desktop. */
+const DEVICE = { width: 424, height: 439 };
+
+/** Wide enough that the queue is a column: 1280 − 200 − 320 ≥ 480. */
+const DESKTOP = { width: 1280, height: 800 };
+
+/**
+ * The Compact band, where the queue is a *screen* (644 − 320 < 480) and
+ * the bottom bar still carries its button.
+ *
+ * Two of these tests need both facts at once and only this band has
+ * them: below 600px #59 takes the button off the bar, so there is no
+ * toggle to re-press and the queue is opened from Now Playing — which
+ * is itself a detail view, so "the destination stays lit" is vacuously
+ * true there rather than tested.
+ */
+const COMPACT = { width: 700, height: 600 };
+
+const activeView = (page: Page) => page.getByTestId('main-content');
+const queue = (page: Page) => page.locator('#queue-panel');
+const toggle = (page: Page) => page.locator('#queue-button');
+
+/**
+ * Whether the queue is up.
+ *
+ * The panel's own attribute rather than the toggle's `aria-expanded`,
+ * because below 600px there is no toggle to ask (#59) — and the panel
+ * is the one fact both of them reflect anyway.
+ */
+async function expectQueue(page: Page, open: boolean): Promise<void> {
+  const panel = queue(page);
+
+  if (open) {
+    await expect(panel).toHaveAttribute('open', '');
+  } else {
+    await expect(panel).not.toHaveAttribute('open', '');
+  }
+}
+
+test.describe('the queue is a screen where it covers the content', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(DEVICE);
+    await app.getByTestId('tab-albums').click();
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
+  });
+
+  // On a phone the queue is opened from Now Playing (#59), so the page
+  // *underneath* it is `now-playing` and the journey is two entries
+  // deep: albums -> now-playing -> queue. That is the real route a user
+  // takes, which is why these do not reach for the shortcut.
+
+  test('back closes the queue and leaves the page where it was', async ({
+    app,
+  }) => {
+    await expect(queue(app)).toHaveAttribute('overlay', '');
+
+    await openTheQueue(app);
+    await expectQueue(app, true);
+
+    await app.goBack();
+
+    await expectQueue(app, false);
+    // The page underneath is untouched. Before #55 this was the
+    // *previous* view, because the queue was not in the stack at all
+    // and back spent an entry navigating something nobody could see.
+    await expect(activeView(app)).toHaveAttribute(
+      'data-active-view',
+      'now-playing',
+    );
+  });
+
+  test('costs exactly one entry, so the next press navigates', async ({
+    app,
+  }) => {
+    await openTheQueue(app);
+    await expectQueue(app, true);
+
+    await app.goBack();
+    await expectQueue(app, false);
+    await expect(activeView(app)).toHaveAttribute(
+      'data-active-view',
+      'now-playing',
+    );
+
+    await app.goBack();
+
+    // Exactly one entry each: the second press leaves Now Playing for
+    // the page it was opened from, rather than being swallowed by a
+    // queue that had already closed.
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
+  });
+
+  /**
+   * Every route out unwinds the entry, and they do it through the
+   * panel's own `open` attribute rather than each knowing about
+   * history — which is why a fourth route added later gets this free.
+   *
+   * The failure this pins is silent: close by button, and if the entry
+   * is orphaned the app looks correct until the next back press does
+   * nothing at all. It is a guard rather than a reproduction — a build
+   * with no entry to orphan passes it — and it is paired with the two
+   * above, which do reproduce.
+   */
+  for (const [name, dismiss] of [
+    [
+      'the close button',
+      async (app: Page) => {
+        await app.getByRole('button', { name: 'Close queue' }).click();
+      },
+    ],
+    [
+      'Escape',
+      async (app: Page) => {
+        await app.keyboard.press('Escape');
+      },
+    ],
+  ] as Array<[string, (app: Page) => Promise<void>]>) {
+    test(`${name} leaves no entry behind`, async ({ app }) => {
+      await openTheQueue(app);
+      await expectQueue(app, true);
+
+      await dismiss(app);
+      await expectQueue(app, false);
+
+      await app.goBack();
+
+      // One press, one screen: Now Playing is what the queue was opened
+      // from, so leaving it lands on Albums. An orphaned entry would
+      // have spent this press on nothing and left it here.
+      await expect(activeView(app)).toHaveAttribute(
+        'data-active-view',
+        'albums',
+      );
+    });
+  }
+
+  /**
+   * A detail view leaves the destination it was opened from lit
+   * (`active-view-store`, #72), and the queue inherits that — it is
+   * published with `isPrimary: false`, so `isActive('albums')` is still
+   * true underneath it.
+   *
+   * `aria-current` rather than a class, for the reason
+   * `back-navigation.spec.ts` gives: the class was right throughout the
+   * bug that rule exists for.
+   */
+
+  /**
+   * With the panel spanning the whole width the scrim has no uncovered
+   * pixels, so the close button is the only pointer route out of a
+   * full-screen surface. Measured at 424×439 before #55: **25×21px**.
+   */
+  test('offers a way out a thumb can hit', async ({ app }) => {
+    await openTheQueue(app);
+
+    const box = await app
+      .getByRole('button', { name: 'Close queue' })
+      .boundingBox();
+
+    expect(box).not.toBeNull();
+    expect(box!.width).toBeGreaterThanOrEqual(44);
+    expect(box!.height).toBeGreaterThanOrEqual(44);
+  });
+});
+
+/**
+ * **The mechanism, because no tier here can see the consequence.**
+ *
+ * #55's Direction asked for a `DETAIL_LOADERS` mount, which would put
+ * the panel inside `.main-panel > *`. That box is paint-contained under
+ * a `.main-panel` that is too, and `contain: paint` makes an element a
+ * containing block for fixed descendants *and clips them* — which is
+ * what a `wa-popup` falls back to on the reference device's Chrome 113,
+ * where the Popover API does not exist (#60, `.planning/NOTES.md`).
+ * `queue-panel` has a context menu, so that mount would have broken a
+ * working menu on the one device this issue is about.
+ *
+ * CI's Chromium and WebKit both *have* the Popover API, so the menu is
+ * top-layered and correct here either way: a spec asserting "the menu is
+ * not clipped" is green on the broken build. What a browser can answer
+ * honestly is where the element is, so that is what this asks.
+ */
+test('the panel stays out of the paint-contained region', async ({ app }) => {
+  await app.setViewportSize(DEVICE);
+
+  // Open, because that is the only state in which a menu can be opened
+  // from it — and because the host drops `paint` from its own
+  // containment deliberately in overlay mode, so a closed panel answers
+  // a different question.
+  await openTheQueue(app);
+  await expectQueue(app, true);
+
+  const ancestry = await app.evaluate(() => {
+    const chain: Array<{ tag: string; contain: string }> = [];
+
+    for (
+      let el = document.getElementById('queue-panel');
+      el && el !== document.documentElement;
+      el = el.parentElement
+    ) {
+      chain.push({
+        tag: el.tagName.toLowerCase(),
+        contain: getComputedStyle(el).contain,
+      });
+    }
+
+    return chain;
+  });
+
+  expect(ancestry.length).toBeGreaterThan(1);
+  expect(ancestry.some((a) => a.tag === 'main')).toBe(false);
+
+  for (const { tag, contain } of ancestry) {
+    expect(
+      `${tag}: ${contain}`,
+      'a paint-contained ancestor clips a fixed-positioned popup on Chrome 113',
+    ).not.toMatch(/paint|content|strict/);
+  }
+});
+
+/**
+ * Two properties need the queue to be a *screen* and the bar to still
+ * have its button, and only the Compact band has both — below 600px #59
+ * takes the button off the bar.
+ */
+test.describe('a screen opened from the bar', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(COMPACT);
+    await app.getByTestId('nav-albums').click();
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
+    await expect(queue(app)).toHaveAttribute('overlay', '');
+  });
+
+  /**
+   * A detail view leaves the destination it was opened from lit
+   * (`active-view-store`, #72), and the queue inherits that — it is
+   * published with `isPrimary: false`, so `isActive('albums')` is still
+   * true underneath it.
+   *
+   * `aria-current` rather than a class, for the reason
+   * `back-navigation.spec.ts` gives: the class was right throughout the
+   * bug that rule exists for.
+   */
+  test('leaves the destination it was opened from highlighted', async ({
+    app,
+  }) => {
+    // By testid, not by role: at 700px the sidebar is in icon mode, so
+    // what the item is *named* is a different question from which item
+    // it is. The assertion is still `aria-current`, which is the
+    // accessible fact.
+    const albums = app.getByTestId('nav-albums');
+
+    await expect(albums).toHaveAttribute('aria-current', 'page');
+
+    await toggle(app).click();
+    await expectQueue(app, true);
+
+    await expect(albums).toHaveAttribute('aria-current', 'page');
+  });
+
+  /** The toggle is a fourth way out, and it unwinds the entry like the
+   *  other three — through the panel's attribute, not its own handler. */
+  test('closes from the same toggle, leaving no entry behind', async ({
+    app,
+  }) => {
+    await toggle(app).click();
+    await expectQueue(app, true);
+
+    await toggle(app).click();
+    await expectQueue(app, false);
+
+    await app.goBack();
+
+    await expect(activeView(app)).not.toHaveAttribute(
+      'data-active-view',
+      'albums',
+    );
+  });
+});
+
+/**
+ * The column is not a place. Somebody docked it; back must not undock
+ * it, and navigating to another view must not take it away.
+ *
+ * This is the half a viewport breakpoint would get wrong: the mode is
+ * computed from the panel's own drag-resizable width, so the queue
+ * becomes a screen exactly when it stops being affordable as a column.
+ */
+test.describe('a docked queue is not in the back stack', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(DESKTOP);
+  });
+
+  test('survives a navigation, and back navigates the page', async ({
+    app,
+  }) => {
+    await app.getByTestId('nav-albums').click();
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
+
+    await toggle(app).click();
+    await expectQueue(app, true);
+    await expect(queue(app)).not.toHaveAttribute('overlay', '');
+
+    await app.getByTestId('nav-artists').click();
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'artists');
+    await expectQueue(app, true);
+
+    await app.goBack();
+
+    await expect(activeView(app)).toHaveAttribute('data-active-view', 'albums');
+    await expectQueue(app, true);
+  });
+});

e2e/specs/queue-overlay.spec.ts

@@ -1,4 +1,4 @@
-import { test, expect } from '../support/fixtures.js';
+import { test, expect, openTheQueue } from '../support/fixtures.js';
 
 /**
  * #24 — the queue panel does not take the page's width away from it.
@@ -54,15 +54,15 @@ const shellGeometry = (page: import('@playwright/test').Page) =>
     };
   });
 
-async function openQueue(page: import('@playwright/test').Page) {
-  const toggle = page.locator('#queue-button');
-
-  if ((await toggle.getAttribute('aria-expanded')) !== 'true') {
-    await toggle.click();
-  }
-
-  await expect(toggle).toHaveAttribute('aria-expanded', 'true');
-}
+/**
+ * Opening the queue is `openTheQueue`, which takes the route this
+ * viewport offers. It used to be a local helper that clicked
+ * `#queue-button` unconditionally, and #59 hid that button below
+ * 600px -- so the two phone bands here failed on a build where the
+ * queue was working perfectly, having been asserting *how* it opens as
+ * much as what it does.
+ */
+const openQueue = openTheQueue;
 
 test.describe('an open queue leaves the content its width', () => {
   for (const band of BANDS) {

e2e/support/fixtures.ts

@@ -140,6 +140,50 @@ export async function navigateTo(page: Page, view: string): Promise<void> {
     .waitFor({ state: 'attached' });
 }
 
+/**
+ * Open the queue the way a user at this viewport would.
+ *
+ * **The route differs by width and that is the feature, not an
+ * inconvenience.** Above 600px the bottom bar carries a queue button.
+ * Below it that button is gone (#59) and the queue is reached from the
+ * full-screen Now Playing view, which the mini player's art opens —
+ * "reachable only from Now Playing", which is what the issue asks for.
+ *
+ * It is here rather than in one spec because four files need it, and
+ * because a spec that hard-codes `#queue-button` is quietly asserting
+ * *which* route exists as well as what the queue does. Four of them
+ * were, which is how hiding one button failed ten tests about
+ * something else.
+ *
+ * The width is read from the page rather than passed, so a caller that
+ * resizes and then opens does not have to say so twice.
+ */
+export async function openTheQueue(page: Page): Promise<void> {
+  const toggle = page.locator('#queue-button');
+
+  if (await toggle.isVisible()) {
+    if ((await toggle.getAttribute('aria-expanded')) !== 'true') {
+      await toggle.click();
+    }
+
+    await expect(toggle).toHaveAttribute('aria-expanded', 'true');
+
+    return;
+  }
+
+  // The phone: through Now Playing. `open-now-playing` is the mini
+  // player's art, which is a button only below 600px.
+  if (
+    (await page.getByTestId('main-content').getAttribute('data-active-view')) !==
+    'now-playing'
+  ) {
+    await page.getByTestId('open-now-playing').click();
+  }
+
+  await page.getByTestId('npv-queue').click();
+  await expect(page.locator('#queue-panel')).toHaveAttribute('open', '');
+}
+
 /** Thin client for the dev-only /__test/ surface (backend/testctl). */
 export class TestCtl {
   constructor(private readonly baseURL: string) {}

frontend/index.css

@@ -535,6 +535,30 @@ body div.sidebar {
     .bottom-bar volume-control {
         display: none;
     }
+
+    /* The queue leaves the phone's bar (#59), because #55 made it a
+       screen with an entry in the back stack and Now Playing already
+       carries its own button for it. The route is the mini player's
+       art -> Now Playing -> the queue, which is the "reachable only
+       from Now Playing" this issue asks for.
+
+       This is allowed to remove a control only because the control is
+       still reachable: plan 018's matrix promises that no action is
+       ever unreachable at any supported size, and that promise is what
+       `phone-transport.spec.ts` asserts rather than the button count.
+
+       **`.bottom-bar #queue-button`, not `#queue-button`**, and that is
+       not decoration. The rule this overrides is written *nested*
+       inside `.bottom-bar`, so it builds to a descendant selector one
+       class more specific than it looks in the source -- and a bare
+       `#queue-button` here loses to it, media query or not. Being last
+       in the file is not enough when the thing above is more specific,
+       which is the same lesson as this section's own header one level
+       down: nesting adds specificity the source does not show, and the
+       failure is silent (the button simply stayed). */
+    .bottom-bar #queue-button {
+        display: none;
+    }
 }
 
 /* Out of the desktop grid entirely.  `job-band` renders nothing above

frontend/index.ts

@@ -67,6 +67,7 @@ import '@store/theme-store';
 import './src/services/keyboard-shortcut-service';
 import { activateView, deactivateView } from '@utils/view-lifecycle';
 import { installLongPressContextMenu } from '@utils/long-press';
+import { openQueue, queuePanelElement } from '@utils/open-queue';
 import { installTopBarFit } from './src/services/top-bar-fit';
 import {
     hasTrackPayload,
@@ -336,6 +337,33 @@ window.addEventListener('popstate', (e: PopStateEvent) => {
     void handleNavigate({ ...nav, _isBack: true });
 });
 
+/**
+ * The queue, while it is a screen (#55).
+ *
+ * It is *not* in `VIEW_TAGS` and *not* in `DETAIL_LOADERS`: there is
+ * nothing to mount, because the panel is already in the document and,
+ * as an overlay, already occupies `.main-panel`'s rect exactly. What a
+ * navigation adds is the two things that make a screen a screen — a
+ * history entry, so the platform's back gesture answers it, and a
+ * destination to leave, so navigating anywhere else takes it away.
+ *
+ * Keeping it out of both tables is what keeps its context menu working
+ * on the reference device: `.main-panel > *` is paint-contained and a
+ * `wa-popup` falls back to `position: fixed` on Chrome 113, which
+ * escapes overflow but not containment (#60). The panel stays in
+ * `.content-area`, which is not paint-contained, exactly as it is
+ * today.
+ */
+const QUEUE_VIEW = 'queue';
+
+/** Close a queue that is being navigated away from. A *column* is not
+ *  a place, so it survives a navigation the way the sidebar does. */
+function dismissQueueScreen(): void {
+    const panel = queuePanelElement();
+
+    if (panel?.hasAttribute('overlay')) panel.removeAttribute('open');
+}
+
 async function handleNavigate(
     detail: { view: string; [key: string]: any },
 ): Promise<void> {
@@ -347,6 +375,25 @@ async function handleNavigate(
 
     if (!detail._isBack) recordNavigation(detail);
 
+    if (view === QUEUE_VIEW) {
+        // The shell says where the user is; `false` because the queue is
+        // not a primary view, so nothing in either nav lights while it
+        // is up -- the same rule a detail view gets, and the reason the
+        // tab the queue was opened from stays lit.
+        activeViewStore.setView(view, false);
+        queuePanelElement()?.setAttribute('open', '');
+
+        // Deliberately not `searchStore.setCurrentView` and not
+        // `dataset.activeView`: both describe what is *in the main
+        // panel*, and the queue covers that panel without replacing it.
+        // Overwriting either would disable the search box belonging to
+        // the page underneath and make every `data-active-view`
+        // selector in the suite disagree with the element it names.
+        return;
+    }
+
+    dismissQueueScreen();
+
     // Bookkeeping stays synchronous with the click: the search box's
     // scope and the active-view attribute describe the navigation that
     // was *asked for*, and are what the rest of the app and the e2e
@@ -631,13 +678,17 @@ const queuePanel = document.getElementById('queue-panel') as HTMLElement | null;
 
 if (queueButton && queuePanel) {
     queueButton.addEventListener('click', () => {
-        const isOpen = queuePanel.hasAttribute('open');
-
-        if (isOpen) {
+        if (queuePanel.hasAttribute('open')) {
+            // Closing goes through the panel either way; where the queue
+            // is a screen the observer below is what unwinds its history
+            // entry, so this button, Escape, the scrim and the close
+            // button all take the same route out.
             queuePanel.removeAttribute('open');
-        } else {
-            queuePanel.setAttribute('open', '');
+
+            return;
         }
+
+        openQueue();
     });
 
     // The button says whether the panel is open, and it learns that
@@ -655,7 +706,39 @@ if (queueButton && queuePanel) {
         );
     };
 
-    new MutationObserver(reflectQueueState).observe(queuePanel, {
+    /**
+     * Keep the back stack honest about a queue that closed itself.
+     *
+     * Where the queue is a screen its `open` attribute and the current
+     * history entry are two statements of one fact, and the panel can
+     * change its half on its own -- Escape, the scrim, the close button,
+     * and anything added later. Reconciling here rather than at each of
+     * those is the same reason this observer already exists for
+     * `aria-expanded`: the attribute is the one fact, and a state kept
+     * beside a click is right until something else changes it.
+     *
+     * Without this the entry is orphaned and the *next* back press is
+     * the one that closes the queue -- a press that appears to do
+     * nothing, which is the defect this issue is about, moved one press
+     * later.
+     *
+     * `history.back()` rather than a stack of our own, for the reason
+     * `navigate-back` does: two stacks is how a component's own way out
+     * and the phone's gesture come to disagree about what one press
+     * means.
+     */
+    const reconcileQueueHistory = () => {
+        if (queuePanel.hasAttribute('open')) return;
+
+        const state = history.state as NavState | null;
+
+        if (state?.yjNav?.view === QUEUE_VIEW) history.back();
+    };
+
+    new MutationObserver(() => {
+        reflectQueueState();
+        reconcileQueueHistory();
+    }).observe(queuePanel, {
         attributes: true,
         attributeFilter: ['open'],
     });

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

@@ -1,22 +1,77 @@
-import { LitElement, html, css } from 'lit';
-import { customElement, state } from 'lit/decorators.js';
+import { LitElement, html, css, nothing } from 'lit';
+import { customElement, property, state } from 'lit/decorators.js';
 import '@awesome.me/webawesome/dist/components/icon/icon.js';
 import { PlayerController } from '@store/controllers/player-controller';
 import { queueStore } from '@store/queue-store';
 import type { RepeatMode } from '@store/queue-store';
 import { designTokens } from '../../../styles/tokens.css';
+import { PHONE_QUERY } from '../../../utils/breakpoints';
+
+/**
+ * The transport, in the two places it appears.
+ *
+ * **The context is a property and cannot be a media query**, which is
+ * the whole reason this exists (#56). Everywhere else in this app a
+ * component states what it drops at phone width itself, because a media
+ * query inside a shadow root is answered by the viewport and that is
+ * the honest signal. Here the two hosts want *different* answers at the
+ * *same* viewport: on a phone the bottom bar wants three controls sized
+ * for a thumb, and `now-playing-view` wants five, larger still. So the
+ * host says which context and the viewport says which size band, and
+ * neither one alone can express it.
+ *
+ * Measured at the reference device's 424x439 before this: every button
+ * here was **33x21px**, in both places, which is what #56 reports as
+ * "the most important thing in the mobile app and they are tiny".
+ */
+export type ControlsContext = 'bar' | 'full';
 
 @customElement('player-controls')
 export class PlayerControls extends LitElement {
   private player = new PlayerController(this);
   private unsubscribeQueue?: () => void;
 
+  /**
+   * Where these controls are drawn. `bar` is the bottom bar in both
+   * bands; `full` is the full-screen transport.
+   *
+   * Reflected so a spec can read it and so the stylesheet keys off one
+   * fact rather than a class the host has to remember to set.
+   */
+  @property({ type: String, reflect: true })
+  context: ControlsContext = 'bar';
+
   @state() private shuffleMode = false;
   @state() private repeatMode: RepeatMode = 'off';
 
+  /**
+   * Phone width, from `matchMedia` rather than from a media query,
+   * because what it decides is whether shuffle and repeat *exist* here
+   * — and a stylesheet can only decide whether they are painted.
+   * `job-band` and `search-trigger` are the same pattern for the same
+   * reason.
+   */
+  @state() private phone = false;
+
+  private media?: MediaQueryList;
+
+  private onMedia = (e: MediaQueryListEvent) => {
+    this.phone = e.matches;
+  };
+
+  /** Whether this is the phone's bottom bar, which carries three
+   *  controls rather than five. */
+  private get slim(): boolean {
+    return this.context === 'bar' && this.phone;
+  }
+
   override connectedCallback(): void {
     super.connectedCallback();
 
+    this.media = window.matchMedia(PHONE_QUERY);
+    this.phone = this.media.matches;
+    this.media.addEventListener('change', this.onMedia);
+
     const s = queueStore.getState();
     this.shuffleMode = s.shuffleMode;
     this.repeatMode = s.repeatMode;
@@ -37,6 +92,7 @@ export class PlayerControls extends LitElement {
   override disconnectedCallback(): void {
     super.disconnectedCallback();
     this.unsubscribeQueue?.();
+    this.media?.removeEventListener('change', this.onMedia);
   }
 
   static override styles = [designTokens, css`
@@ -58,6 +114,99 @@ export class PlayerControls extends LitElement {
       justify-content: center;
     }
 
+    /* ---------------------------------------------------------------
+       Sizes (#56).
+
+       44px is the floor everything here is sized to, and play/pause
+       alone goes above it -- "large play/pause, adequate prev/next" is
+       the Direction, and it is the one control the report calls "front
+       and centre".
+
+       They are stated as custom properties rather than on each button
+       so a context sets two numbers instead of five rules, and so the
+       icon scales with its target: a 44px box around a 16px glyph is a
+       big hit area that still looks tiny, which is half of what the
+       report is about.
+
+       **The desktop bar sets none of them and must not change at all.**
+       #56 is an Android issue; the desktop's buttons are 33x21 before
+       this and are 33x21 after it.
+
+       That is why the box rules take a zero fallback and the *font-size*
+       rules are scoped to the two contexts instead of sharing them. A
+       button does not inherit its font from its parent -- the UA
+       stylesheet gives it one -- so a generic font-size: inherit is
+       not the no-op it reads as: it moved the desktop's buttons from
+       33x21 to 36x24, silently, by taking them from the UA's 13.3px to
+       the shell's 16px. Measured before and after by stashing this
+       file, which is the only way that particular 3px shows up.
+       --------------------------------------------------------------- */
+    button {
+      min-width: var(--yj-control-target, 0);
+      min-height: var(--yj-control-target, 0);
+    }
+
+    button.play {
+      min-width: var(--yj-control-play-target, 0);
+      min-height: var(--yj-control-play-target, 0);
+    }
+
+    /* The phone's bottom bar: three controls, sized for a thumb.
+       Shuffle and repeat are not here -- see the render method, which
+       does not draw them rather than hiding them, because a control
+       that is display:none is still a thing the component claims to
+       have. They are on the full-screen view, which is one tap away
+       through the mini player's art (#59). */
+    @media (max-width: 599px) {
+      :host([context='bar']) {
+        --yj-control-target: 44px;
+        --yj-control-icon: 18px;
+        --yj-control-play-target: 56px;
+        --yj-control-play-icon: 24px;
+      }
+
+      :host([context='bar']) button {
+        font-size: var(--yj-control-icon);
+      }
+
+      :host([context='bar']) button.play {
+        font-size: var(--yj-control-play-icon);
+      }
+    }
+
+    /* The full-screen transport, at every width: this view *is* the
+       player, so the controls are the page rather than a strip of it. */
+    :host([context='full']) {
+      --yj-control-target: 44px;
+      --yj-control-icon: 20px;
+      --yj-control-play-target: 64px;
+      --yj-control-play-icon: 28px;
+    }
+
+    :host([context='full']) button {
+      font-size: var(--yj-control-icon);
+    }
+
+    :host([context='full']) button.play {
+      font-size: var(--yj-control-play-icon);
+    }
+
+    :host([context='full']) #player-control-buttons {
+      gap: 12px;
+    }
+
+    /* Secondary controls sit below the primary row rather than beside
+       it, which is the Direction's shape and is why this is a second
+       group in the DOM instead of a CSS order property: visual order
+       and focus order have to agree. */
+    .secondary {
+      display: flex;
+      justify-content: center;
+      align-items: center;
+      gap: 24px;
+      margin-top: 8px;
+    }
+
     button:hover {
       color: var(--yj-accent-text, #ffd43b);
     }
@@ -104,46 +253,107 @@ export class PlayerControls extends LitElement {
     queueStore.cycleRepeat();
   };
 
-  override render() {
-    const playOrPauseIcon = this.player.isPlaying ? 'pause' : 'play';
-    const playOrPauseHandler = this.player.isPlaying
-      ? this.handlePauseClick
-      : this.handlePlayClick;
+  /** Shuffle. Secondary: it changes how the queue behaves rather than
+   *  what is playing now. */
+  private renderShuffle() {
+    return html`
+      <button
+        class=${this.shuffleMode ? 'active' : ''}
+        aria-label="Shuffle"
+        aria-pressed=${this.shuffleMode}
+        @click=${this.handleShuffleClick}
+      >
+        <wa-icon name="shuffle"></wa-icon>
+      </button>
+    `;
+  }
 
-    const shuffleClass = this.shuffleMode ? 'active' : '';
+  /** Repeat, whose label spells the mode out because one icon covers
+   *  three states. */
+  private renderRepeat() {
     const repeatMode = this.repeatMode;
     const repeatClasses = [
       repeatMode !== 'off' ? 'active' : '',
       repeatMode === 'one' ? 'repeat-one' : '',
     ].filter(Boolean).join(' ');
 
+    return html`
+      <button
+        class=${repeatClasses}
+        aria-label=${`Repeat: ${repeatMode}`}
+        aria-pressed=${repeatMode !== 'off'}
+        @click=${this.handleRepeatClick}
+      >
+        <wa-icon name="repeat"></wa-icon>
+      </button>
+    `;
+  }
+
+  /** Previous, play/pause, next — the three that are always drawn, in
+   *  every context and at every width. Only play/pause takes the large
+   *  size: the Direction asks for "large play/pause, adequate
+   *  prev/next", and a row of identical squares says every action here
+   *  is equally likely, which is not true of play. */
+  private renderPrimary() {
+    const playOrPauseIcon = this.player.isPlaying ? 'pause' : 'play';
+    const playOrPauseHandler = this.player.isPlaying
+      ? this.handlePauseClick
+      : this.handlePlayClick;
+
+    return html`
+      <button
+        aria-label="Previous track"
+        @click=${this.handlePreviousClick}
+      >
+        <wa-icon name="backward-step"></wa-icon>
+      </button>
+      <button
+        class="play"
+        aria-label=${this.player.isPlaying ? 'Pause' : 'Play'}
+        @click="${playOrPauseHandler}"
+      >
+        <wa-icon name=${playOrPauseIcon}></wa-icon>
+      </button>
+      <button
+        aria-label="Next track"
+        @click=${this.handleNextClick}
+      >
+        <wa-icon name="forward-step"></wa-icon>
+      </button>
+    `;
+  }
+
+  /**
+   * Two arrangements, not two components.
+   *
+   * `bar` keeps the order it has always had — shuffle, prev, play,
+   * next, repeat, one row — so nothing about the desktop bar moves.
+   * `full` puts the primary three on their own row with the secondary
+   * pair beneath, which the Direction asks for.
+   *
+   * **The phone's bar draws three buttons rather than hiding two.** A
+   * `display: none` control is still in the component's shadow root,
+   * still in the accessibility tree's markup, and still something a
+   * `shadowAll('button')[4]` finds — so "the phone has three controls"
+   * would be true of the pixels and false of the element. They are
+   * reachable on the full-screen view, which the mini player's art
+   * opens, and through the global shortcuts.
+   */
+  override render() {
+    if (this.context === 'full') {
+      return html`
+        <div id="player-control-buttons">${this.renderPrimary()}</div>
+        <div class="secondary">
+          ${this.renderShuffle()}${this.renderRepeat()}
+        </div>
+      `;
+    }
+
     return html`
       <div id="player-control-buttons">
-        <button
-          class=${shuffleClass}
-          aria-label="Shuffle"
-          aria-pressed=${this.shuffleMode}
-          @click=${this.handleShuffleClick}
-        >
-          <wa-icon name="shuffle"></wa-icon>
-        </button>
-        <button aria-label="Previous track" @click=${this.handlePreviousClick}>
-          <wa-icon name="backward-step"></wa-icon>
-        </button>
-        <button aria-label=${this.player.isPlaying ? 'Pause' : 'Play'} @click="${playOrPauseHandler}">
-          <wa-icon name=${playOrPauseIcon}></wa-icon>
-        </button>
-        <button aria-label="Next track" @click=${this.handleNextClick}>
-          <wa-icon name="forward-step"></wa-icon>
-        </button>
-        <button
-          class=${repeatClasses}
-          aria-label=${`Repeat: ${repeatMode}`}
-          aria-pressed=${repeatMode !== 'off'}
-          @click=${this.handleRepeatClick}
-        >
-          <wa-icon name="repeat"></wa-icon>
-        </button>
+        ${this.slim ? nothing : this.renderShuffle()}
+        ${this.renderPrimary()}
+        ${this.slim ? nothing : this.renderRepeat()}
       </div>
     `;
   }

frontend/src/components/now-playing-view/now-playing-view.ts

@@ -15,6 +15,7 @@ import { FavoritesController } from '@store/controllers/favorites-controller';
 import { designTokens } from '../../styles/tokens.css';
 import { srOnly } from '../../styles/sr-only.css';
 import { ICON_QUEUE } from '@utils/icon-language';
+import { openQueue as showQueue } from '@utils/open-queue';
 
 /**
  * What is playing, at the size a phone has room for (plan 016 B2,
@@ -116,8 +117,27 @@ export class NowPlayingView extends LitElement {
         .art .placeholder {
             /* Square, and never taller than the room left over: the
                art is the one thing here that would happily push the
-               transport off the bottom of a short phone. */
+               transport off the bottom of a short phone.
+
+               **max-height is what actually keeps that promise**, and
+               it was missing. With a definite width and
+               a 1:1 aspect-ratio the height is *derived from the width*
+               and is bounded by nothing: at the reference device's
+               424x439 that is a 263px square (60vh) in a box with far
+               less than 263px left, so the art overflowed its own
+               centred flex item and drew over the header above and the
+               title below it. The comment claimed this was handled;
+               60vh is a bound on the *viewport*, not on the room left
+               over, and those differ by however much chrome is above
+               and below.
+
+               Pre-existing -- screenshotted on main -- and made acute
+               by #56, which gives the transport 95px more than it had.
+               Found by reading a screenshot, which is the only tier
+               that can see it: nothing fails, nothing overflows the
+               *shell*, and every control is still hittable. */
             width: min(100%, 60vh);
+            max-height: 100%;
             aspect-ratio: 1;
             object-fit: cover;
             border-radius: 12px;
@@ -226,13 +246,15 @@ export class NowPlayingView extends LitElement {
      *
      * This view hides the bottom bar (index.css), and the bar is where
      * the queue button lives -- so without this, going full-screen
-     * would take the queue away. It toggles the same `open` attribute
+     * would take the queue away. It goes through the same helper
      * `index.ts` does, because the panel's state is an attribute on one
      * element and a second mechanism for it is a second thing to keep
-     * in step.
+     * in step -- which is exactly what this button was: it set `open`
+     * directly, so on a phone it produced a queue with no history entry
+     * behind it and back moved the page underneath instead (#55).
      */
     private openQueue() {
-        document.getElementById('queue-panel')?.setAttribute('open', '');
+        showQueue();
     }
 
     private toggleFavorite() {
@@ -314,7 +336,13 @@ export class NowPlayingView extends LitElement {
 
             <div class="transport">
                 <seek-bar></seek-bar>
-                <player-controls></player-controls>
+                <!-- context="full": this view *is* the player, so the
+                     transport is the page rather than a strip of it --
+                     primary controls large, shuffle and repeat beneath
+                     at normal size (#56). It is a property rather than
+                     a media query because the bottom bar wants a
+                     different answer at this same viewport. -->
+                <player-controls context="full"></player-controls>
                 <volume-control></volume-control>
             </div>
         `;

frontend/src/components/now-playing/now-playing.ts

@@ -215,6 +215,17 @@ export class NowPlaying extends LitElement {
         outline: 2px solid var(--yj-accent, #ffd43b);
         outline-offset: 2px;
       }
+
+      /* The favourite is one of the three controls #59 keeps on the
+         phone's bar, and it was the **smallest control in the app**:
+         measured at 424x439, 18x14px, against the 48x48 art beside it.
+         Zero padding around an icon-sized glyph is a reasonable mouse
+         target and is not a thumb target at all. */
+      .fav-btn {
+        min-width: 44px;
+        min-height: 44px;
+        font-size: var(--yj-icon-md);
+      }
     }
 
     .cover-preview-panel {
@@ -446,8 +457,30 @@ export class NowPlaying extends LitElement {
             return html`
         <div class="sr-only" role="status" aria-live="polite">${announcement}</div>
         <div class="now-playing">
-          <div class="cover-art">
-            <div class="cover-placeholder"><wa-icon name="music"></wa-icon></div>
+          <!-- **The way to Now Playing does not depend on what is
+               playing.** This branch used to render the placeholder
+               with no button on it, so on a phone there was no route to
+               the full-screen view while nothing was loaded -- and once
+               #59 took the queue button off the bar, that made the
+               queue itself unreachable, because Now Playing is where it
+               is reached from. The queue is persisted across restarts,
+               so "a queue with tracks in it and nothing playing" is an
+               ordinary state to launch into, not a corner.
+
+               Plan 018's matrix promises no action is unreachable at
+               any supported size, and the promise is what makes #59
+               allowed to remove a control at all. -->
+          <div class="cover-art-wrapper">
+            <button
+              type="button"
+              class="expand"
+              data-testid="open-now-playing"
+              aria-label="Open now playing"
+              @click=${this.openNowPlaying}
+            ></button>
+            <div class="cover-art">
+              <div class="cover-placeholder"><wa-icon name="music"></wa-icon></div>
+            </div>
           </div>
         </div>
         <div

frontend/src/components/queue-panel/queue-panel.ts

@@ -410,6 +410,22 @@ export class QueuePanel
             :host([overlay]) .panel-content {
                 width: 100%;
             }
+
+            /* A screen's way out has to be hittable with a thumb.
+               Measured at 424x439 before #55: these were **25x21px**,
+               and with the panel spanning the whole width the scrim
+               underneath has no uncovered pixels at all -- so it was
+               the only pointer route out of a full-screen surface.
+               Back answers it now as well, which is the other half.
+
+               Sized only in overlay mode: inline these sit in a 320px
+               column beside the content, where a mouse is what reaches
+               them and 44px of header is 44px the queue does not get. */
+            :host([overlay]) .header-action-button {
+                min-width: 44px;
+                min-height: 44px;
+                justify-content: center;
+            }
         }
 
         .resize-handle {

frontend/src/utils/open-queue.ts

@@ -0,0 +1,54 @@
+/**
+ * Opening the queue, from the two buttons that do it.
+ *
+ * **The queue is a place while it is covering the content, and a
+ * control while it sits beside it** (#55). Those are not two components
+ * and not two mount points — they are the two presentations #24 already
+ * computes, and this is the one line that turns that measurement into a
+ * navigation decision.
+ *
+ * A column is a thing the user docked: back must not undock it, and
+ * navigating to Albums must not take it away. An overlay is a screen —
+ * at the reference device's 424x439 it is 424x318, which is
+ * `.main-panel`'s rect exactly — so it needs the two things a screen
+ * has and this one did not: an entry in the back stack, and a way out
+ * that answers the platform's own gesture. Measured before this existed:
+ * opening the queue on Artists and pressing back moved the page
+ * *underneath* to Albums and left the queue up.
+ *
+ * The mode is read off the panel rather than from a viewport width, for
+ * the reason `queue-panel.overlay` is computed at all: the panel is
+ * drag-resizable between 200 and 500px and persisted, so a breakpoint
+ * is wrong by up to 180px in the direction that hurts.
+ */
+export function queuePanelElement(): HTMLElement | null {
+    return document.getElementById('queue-panel');
+}
+
+/** Whether the queue is currently a screen rather than a column. */
+export function queueIsAScreen(): boolean {
+    return queuePanelElement()?.hasAttribute('overlay') ?? false;
+}
+
+/**
+ * Show the queue: a navigation where it is a screen, an attribute where
+ * it is a column.
+ *
+ * Both routes end at the same `open` attribute on the same element —
+ * `index.ts` handles `navigate {view: 'queue'}` by setting it — because
+ * the panel's state is one fact and a second mechanism for it is a
+ * second thing to keep in step.
+ */
+export function openQueue(): void {
+    if (queueIsAScreen()) {
+        document.dispatchEvent(new CustomEvent('navigate', {
+            bubbles: true,
+            composed: true,
+            detail: { view: 'queue' },
+        }));
+
+        return;
+    }
+
+    queuePanelElement()?.setAttribute('open', '');
+}

frontend/test/components/transport-context.test.ts

@@ -0,0 +1,181 @@
+/**
+ * The transport in its two contexts (#59, #56).
+ *
+ * `player-controls` is one component in two places, and what each place
+ * wants differs *at the same viewport*: on a phone the bottom bar wants
+ * three controls sized for a thumb, and `now-playing-view` wants five,
+ * larger still. So the host states the context and the viewport states
+ * the size band, and this file pins the half a media query cannot
+ * express.
+ *
+ * **What this tier can and cannot see.** It can see which buttons
+ * exist, because that is `matchMedia` and a render — and existence is
+ * the whole of #59. It cannot see the *sizes*: those come from the
+ * context's custom properties, and a component-tier render has no shell
+ * around it, so the measurements live in `e2e/specs/phone-transport.spec.ts`
+ * where there is a real bar in a real viewport. Asserting a pixel here
+ * would be asserting the fallbacks, which is `ui-visual`'s documented
+ * blind spot one tier over.
+ */
+import { describe, expect, it, beforeEach, afterEach } from 'vitest';
+
+import '@components/audio-player/controls/player-controls';
+import { Events } from '../../src/events';
+import { emit, flush, calls } from '@test/support/harness';
+import { fixture, shadowAll, click } from '@test/support/render';
+
+/** Reset the backend-owned state the component reads from. */
+function idle(): void {
+  emit(Events.TrackChanged, null);
+  emit(Events.PlaybackStateChanged, { state: 'stopped' });
+  emit(Events.QueueModeChanged, { shuffleMode: false, repeatMode: 'off' });
+}
+
+const names = (el: Element): Array<string | null> =>
+  shadowAll(el, 'button').map((b) => b.getAttribute('aria-label'));
+
+/**
+ * Answer `matchMedia` for the phone query, since the test runner's own
+ * window is whatever size the browser provider gives it.
+ *
+ * It is stubbed rather than resized because what is under test is the
+ * component's *reaction* to the answer, and a resize would additionally
+ * be asserting that this runner's viewport can get below 600px.
+ */
+const realMatchMedia = window.matchMedia;
+
+function pretendPhone(phone: boolean): void {
+  window.matchMedia = ((query: string) => ({
+    matches: phone && query.includes('599'),
+    media: query,
+    addEventListener: () => {},
+    removeEventListener: () => {},
+  })) as unknown as typeof window.matchMedia;
+}
+
+afterEach(() => {
+  window.matchMedia = realMatchMedia;
+});
+
+describe('<player-controls> in the bar', () => {
+  beforeEach(() => {
+    idle();
+  });
+
+  it('keeps all five on a desktop, in the order it always had', async () => {
+    pretendPhone(false);
+
+    const el = await fixture('player-controls');
+
+    // Unchanged from before #59, deliberately: this is the desktop bar
+    // and nothing about it was reported.
+    expect(names(el)).toEqual([
+      'Shuffle',
+      'Previous track',
+      'Play',
+      'Next track',
+      'Repeat: off',
+    ]);
+  });
+
+  it('draws three on a phone, and does not merely hide the other two', async () => {
+    pretendPhone(true);
+
+    const el = await fixture('player-controls');
+
+    expect(names(el)).toEqual(['Previous track', 'Play', 'Next track']);
+
+    // The distinction this asserts is the point. A `display: none`
+    // control is still in the shadow root, still something a positional
+    // query finds, and still a thing the component claims to have --
+    // so "the phone has three controls" would have been true of the
+    // pixels and false of the element.
+    expect(shadowAll(el, 'button')).toHaveLength(3);
+  });
+
+  it('follows the viewport when it changes, not just at construction', async () => {
+    pretendPhone(false);
+
+    const el = await fixture('player-controls');
+
+    expect(names(el)).toHaveLength(5);
+
+    // A desktop window dragged narrow is the phone layout, per plan
+    // 018's decision 4 -- so this is a real transition and not a
+    // hypothetical.
+    (el as unknown as { phone: boolean }).phone = true;
+    await flush();
+    await el.updateComplete;
+
+    expect(names(el)).toEqual(['Previous track', 'Play', 'Next track']);
+  });
+});
+
+describe('<player-controls> full-screen', () => {
+  beforeEach(() => {
+    idle();
+  });
+
+  it('keeps all five on a phone, where the bar keeps three', async () => {
+    pretendPhone(true);
+
+    const el = await fixture('player-controls');
+
+    el.setAttribute('context', 'full');
+    await el.updateComplete;
+
+    // The same viewport, the other answer: this is why the context is a
+    // property and cannot be a media query.
+    expect(names(el)).toHaveLength(5);
+  });
+
+  it('puts the secondary pair after the primary three, in the DOM', async () => {
+    pretendPhone(true);
+
+    const el = await fixture('player-controls');
+
+    el.setAttribute('context', 'full');
+    await el.updateComplete;
+
+    // Order, not just membership: the secondary controls are drawn on a
+    // second row, and this is asserted in the DOM because visual order
+    // and focus order have to agree. A CSS `order` property would move
+    // them on screen and leave Tab walking the old sequence.
+    expect(names(el)).toEqual([
+      'Previous track',
+      'Play',
+      'Next track',
+      'Shuffle',
+      'Repeat: off',
+    ]);
+  });
+
+  it('still routes every button to the backend', async () => {
+    pretendPhone(true);
+
+    const el = await fixture('player-controls');
+
+    el.setAttribute('context', 'full');
+    await el.updateComplete;
+
+    // Two arrangements, one set of handlers. The regression this
+    // guards is the reason a second *component* was refused: a second
+    // template renders buttons wired to nothing, which looks perfect
+    // in a screenshot and does nothing at all.
+    for (const name of [
+      'Previous track',
+      'Next track',
+      'Shuffle',
+      'Repeat: off',
+    ]) {
+      await click(el, `button[aria-label="${name}"]`);
+    }
+
+    expect(calls().map((c) => c.path)).toEqual([
+      'queue.Queue.Previous',
+      'queue.Queue.Next',
+      'queue.Queue.ToggleShuffle',
+      'queue.Queue.CycleRepeat',
+    ]);
+  });
+});

frontend/test/utils/open-queue.test.ts

@@ -0,0 +1,101 @@
+/**
+ * Opening the queue is a *navigation* where the queue is a screen, and
+ * an *attribute* where it is a column (#55).
+ *
+ * This is the one decision in that change, so it is pinned at the tier
+ * that can state it without a shell: the mode is read off the panel's
+ * own `overlay` attribute — which #24 computes from the measured widths
+ * — and never from a viewport breakpoint. A breakpoint would silently
+ * assume the default 320px panel and be wrong by up to 180px for a user
+ * who has dragged it wide, in the direction that hurts.
+ *
+ * What this tier cannot see is the other half: that the entry is
+ * unwound when the panel closes, which lives in the shell's mutation
+ * observer. `e2e/specs/queue-as-a-screen.spec.ts` is where that is
+ * asserted, and it is asserted as *two* back presses rather than one.
+ */
+import { afterEach, describe, expect, it } from 'vitest';
+
+import { openQueue, queueIsAScreen } from '@utils/open-queue';
+
+function panel(overlay: boolean): HTMLElement {
+    const el = document.createElement('div');
+
+    el.id = 'queue-panel';
+    if (overlay) el.setAttribute('overlay', '');
+    document.body.appendChild(el);
+
+    return el;
+}
+
+function recordNavigations(): string[] {
+    const seen: string[] = [];
+    const listener = (e: Event) => {
+        seen.push((e as CustomEvent).detail.view);
+    };
+
+    document.addEventListener('navigate', listener);
+    cleanup.push(() => document.removeEventListener('navigate', listener));
+
+    return seen;
+}
+
+const cleanup: Array<() => void> = [];
+
+afterEach(() => {
+    while (cleanup.length) cleanup.pop()!();
+    document.getElementById('queue-panel')?.remove();
+});
+
+describe('opening the queue', () => {
+    it('navigates where the queue covers the content', () => {
+        const el = panel(true);
+        const seen = recordNavigations();
+
+        expect(queueIsAScreen()).toBe(true);
+
+        openQueue();
+
+        expect(seen).toEqual(['queue']);
+        // The shell answers the navigation by setting the attribute, so
+        // the helper deliberately does *not* set it as well: two
+        // mechanisms for one fact is two things to keep in step, which
+        // is what `now-playing-view`'s copy of this button was.
+        expect(el.hasAttribute('open')).toBe(false);
+    });
+
+    it('sets the attribute where the queue is a column', () => {
+        const el = panel(false);
+        const seen = recordNavigations();
+
+        expect(queueIsAScreen()).toBe(false);
+
+        openQueue();
+
+        // A column is a thing the user docked. Back must not undock it,
+        // so it is not a history entry and therefore not a navigation.
+        expect(seen).toEqual([]);
+        expect(el.hasAttribute('open')).toBe(true);
+    });
+
+    it('follows the panel rather than the viewport', () => {
+        const el = panel(false);
+        const seen = recordNavigations();
+
+        openQueue();
+        expect(seen).toEqual([]);
+
+        // Nothing about the window changed; the panel got wider, which
+        // is exactly the case a media query cannot express.
+        el.removeAttribute('open');
+        el.setAttribute('overlay', '');
+
+        openQueue();
+        expect(seen).toEqual(['queue']);
+    });
+
+    it('says the queue is not a screen when there is no panel at all', () => {
+        expect(queueIsAScreen()).toBe(false);
+        expect(() => openQueue()).not.toThrow();
+    });
+});