Merge pull request 'Split the README into a user-facing landing page and CONTRIBUTING.md' (#221) from docs/50-readme-landing-page into main

`queueSixAndOpen` filters the queue down to tracks that have an album,
because `explore-link` renders a name it cannot route as plain text and
one test clicks that name. The filter is right and unchanged; the
comment explaining it named the wrong two files.

Since #104 read a WAV's `id3 ` chunk, the two tracks under `Field
Recordings/Test Tones` are tagged, scanned and ordinary. Asked of a
seeded app rather than of the comment, exactly two tracks in the
fixture library have no album: `unsorted/no-tags-at-all.mp3` and
`unsorted/title-only.mp3`.

The clause saying which change made the old names wrong is there so the
next reader does not restore them.

Closes #217

.pi/skills/yellowjacket-dev/SKILL.md

@@ -158,7 +158,7 @@ only climb when it cannot.
 | You changed | Run | Cost |
 |---|---|---|
 | A Lit component, a store, the shortcut service | `make ui-test` | ~2 s, no app |
-| …and it renders differently | `make ui-visual` | + 6 baselines, opt-in |
+| …and it renders differently | `make ui-visual` | + 10 baselines, opt-in, never gates |
 | Any Go code | `make test` | 3 passes, ~2 min |
 | A service that emits events | `make test` — assert on the payload, see `backend/queue/emit_test.go` | in-process, no app |
 | A bound method or a bound struct field | `make bindings` then `make ui-test` | ~1.5 s + 2 s |
@@ -180,6 +180,13 @@ less than it looks.)
 
 Two rules about climbing:
 
+- **If you moved a component's geometry, run `make ui-visual` and
+  refresh that component's baseline in the same commit.** Nothing else
+  will: it is the one tier in this repo no hook and no CI job runs, and
+  it cannot be one — its references are machine-specific, measured in
+  [references/ui-tier.md](references/ui-tier.md). Four of them drifted
+  across three merges before anyone noticed (#196). Read the image;
+  never bless a reference you did not cause.
 - **A component test passing is not the app rendering.** If you touched
   anything in `frontend/src`, verify it in the real app too — start it
   headless, `screenshot --filename=/tmp/shot.png`, and *read the PNG*.

.pi/skills/yellowjacket-dev/references/ui-tier.md

@@ -78,9 +78,58 @@ synchronously.
   Microtasks and not a timer, deliberately: a timer hangs forever under
   the suites that install fake ones.
 
-Visual baselines are font-hinting and compositing sensitive, which is
+## The visual tier does not gate, and that is measured (#196)
-why they are opt-in: they only mean anything on the machine that
+
-recorded them.
+`make ui-visual` is the same suite with nine `toMatchScreenshot`
+baselines switched on. **Nothing runs it but a person**, deliberately,
+and the reason is a number rather than a preference: the committed
+baselines were recorded on Arch, and replayed in a bare `ubuntu:24.04`
+container — CI's `check` image — three of them fail for reasons that
+have nothing to do with any component.
+
+| baseline | Arch | ubuntu:24.04 |
+|---|---|---|
+| `page-header` filtered-by-search | passes | ratio 0.03 differ, against a 0.02 allowance |
+| `track-info` | passes | ratio 0.03 differ |
+| `seek-bar` | 1152×18 | 1152×17 |
+
+The two references that were genuinely stale did not even agree about
+their *new* size — `now-playing` renders 1152×65 on Arch and 1152×64 in
+the container. So moving CI's `check` job from `make ui-test` to
+`make ui-visual` is not a one-line change: it needs a second,
+container-recorded baseline set, which every local run would then fail
+against. That is the same trap the other way round, and a pre-push hook
+is the same fault again — one machine's baselines against everybody
+else's renderer.
+
+So the tier stays local and opt-in, and the rule that replaces the gate
+is:
+
+- **A change that moves a component's geometry refreshes that
+  component's reference in the same commit, having read the image.**
+  Look at the PNG; the dimensions in the failure message are the cheap
+  half of the answer.
+- **Never refresh a reference you did not cause.** #196 exists because
+  four of them drifted across three unrelated merges, and every red run
+  made the next person likelier to stop running the tier than to read
+  it.
+- **State the world the shot is taken in.** The stores are singletons,
+  so a visual case that sets nothing photographs whatever the previous
+  case left behind — which is how the sidebar's baseline came to have
+  Tracks lit and `now-playing`'s to be playing from a dynamic mix.
+- **Record one file with `make ui-visual-update UI_ARGS=<path>`**, and
+  check `git status` before committing either way. That filter is only
+  honoured since #204: the recipe was a bare `--update`, and vitest
+  takes the following positional as the flag's value, so the path was
+  swallowed and *every* baseline was re-recorded — blessing any stale
+  one in silence.
+
+What the tier is worth, for the record: it is a *layout* check, blind to
+colour (the component tier has no `:root`, so it renders the fallbacks —
+`make ui-visual` passed unchanged through a whole palette rewrite,
+twice), and it has caught one thing nothing else could — swapping
+`library-status-indicator`'s `<button>` for a `<span>` lost the UA
+stylesheet's `box-sizing` and grew the badge 36→38px.
 
 ## Bindings
 

.planning/NOTES.md

@@ -4912,3 +4912,169 @@ bridge leaves the wizard up with its "Get Started" button correctly
 disabled — it gates on a directory chosen *in the wizard*, and the
 existing-library check runs once, on mount. A reload clears it. Nothing
 is broken; it cost twenty minutes of believing a tap had been swallowed.
+
+## The sheet's scroll fade, and where a scrim may not go (measured 2026-08-23, headless)
+
+#207's answer. The affordance is two background layers on
+`wa-dialog::part(body)` and the conditionality is
+`background-attachment`, not a scroll listener: a cover of the sheet's
+own colour painted at the end of the *content* (`local`) over a shadow
+pinned to the box (`scroll`), so the cover scrolls up and hides the
+shadow exactly when there is nothing more to see.
+
+Measured at 424x360 (which is where a menu overflows on `main`, since
+`main` does not yet carry #67's eighth item — at 424x439 the track
+list's seven items are `scrollHeight` 364 against `clientHeight` 364,
+fitting exactly). Pixel at x=300, dark ramp, `bgElevated` `#343a40`:
+
+| y | before | more below | at the end of the list |
+|---|---|---|---|
+| 330 | 52,58,64 | 50,56,62 | 52,58,64 |
+| 340 | 52,58,64 | 43,48,53 | 52,58,64 |
+| 350 | 52,58,64 | 33,37,40 | 52,58,64 |
+| 359 | 52,58,64 | 22,24,27 | 52,58,64 |
+
+Three things worth keeping.
+
+**A menu that fits draws nothing**, which is the same measurement: at
+424x439 the sheet is flat 52,58,64 to its bottom edge, because with no
+overflow the `local` layer's positioning area *is* the padding box and
+the cover lands on top of the shadow.
+
+**A scrim over a menu row is that row's text surface**, so the 4.5:1
+rule reaches it and this is why the curve is steep rather than linear.
+A row is 48px with its label centred; 32px of scrim already down to a
+quarter strength at 14px puts about 0.06 at the label. Checked on the
+light ramp (`bgElevated` `#e9ecef`, text `#212529`) by overriding the
+two custom properties on `:root`: background at the label 205,207,210,
+which is **9.9:1**. The first draft — a linear 48px at 0.8 — put ~0.375
+on that label, 5.0:1, passing but visibly greyed. The bottom few pixels
+go to ~2.4:1 in either draft and are deliberately below where any
+label of a *fully visible* row sits; a label that lands there belongs
+to the half-cut row, which is the thing being signalled.
+
+**A dark scrim on a dark surface reads far worse in a shrunk screenshot
+than on screen.** The first two probes (24px/0.45, then 32px/0.75) were
+measurably present — 52,58,64 down to 30,33,37 — and invisible in the
+inline preview. Crop the bottom 70px and scale it up before judging;
+the pixel values are the honest answer either way.
+
+## The phone's context sheet is now longer than the phone (measured 2026-08-23, headless at 424x439)
+
+#67 moves two destinations into every row menu, and the track list's
+menu is where that runs out of screen. Measured against the running
+app at the reference viewport, one row selected:
+
+| menu | items | first item top | last item bottom |
+|---|---|---|---|
+| queue panel | 7 | 95 | 431 |
+| track list | 8 | 86 | **470** |
+
+The viewport is 439. So the track list's last item — "Remove from
+Library" — is below the fold. It is **not unreachable**: the sheet is a
+`wa-dialog` whose body is `overflow-y: auto`, measured `scrollHeight`
+412 against `clientHeight` 373, and scrolling it 39px brings that item
+fully into view (383–431). What it has is no *affordance*: nothing on
+screen says the list continues.
+
+Two things worth knowing before adding a ninth item anywhere.
+
+**The limit was already reached, and this is what crossed it.** Seven
+48px rows in a 373px body is 364px — the queue's menu fits with 8px to
+spare and the track list's fitted exactly. Any item added to any of the
+fourteen menus after #60 was going to be the one that overflowed; the
+first one simply happened to be this.
+
+**The measurement has to be taken with a row selected**, since the
+`Go to` items are drawn for a single selection only, and on the *first*
+track of the fixture library — which has no album (`01 Tone A`,
+`02 Tone B`) — only "Go to Artist" appears. That is the 8 above; an
+ordinary track makes it 9.
+
+Filed as its own issue rather than fixed in #67's diff: it is a
+property of the shared sheet (`components/menu-surface/`), not of the
+items.
+
+## The tap highlight is one inherited declaration (measured 2026-08-24)
+
+`-webkit-tap-highlight-color` is an **inherited** property, and an
+inherited property crosses a shadow boundary — so `html { … :
+transparent }` in `index.css` reaches every shadow root in the app and
+no component needs a rule of its own. Measured in the running app
+(Chromium, `app-sidebar`'s `li button`, which is three shadow roots
+from the document): `rgba(0, 0, 0, 0)` with the rule, and
+`rgba(0, 0, 0, 0.18)` with it removed. That 0.18 grey over the bounding
+rect of whatever was tapped is what #54 reported.
+
+The same argument was already spent once and is worth not
+re-deriving: `index.css`'s first rule is `*, *::before, *::after {
+user-select: none }`, which for the same reason already covers the
+shadow roots — #54's Findings ask for `user-select` on interactive
+surfaces and it has been done since before the issue was filed.
+
+**What the highlight was, on the surfaces that had nothing else, is the
+press feedback.** Measured on a track row with the press rule removed
+and the button held down: `rgba(255, 255, 255, 0.05)` — the *hover*
+tint, arriving because the pointer is over the row, which is a
+synthesised hover on a phone and outlives the press. With the rule:
+0.12 while held, and the neighbouring row unchanged. So the press state
+is part of removing the highlight rather than a separate polish item,
+and the hover tints on those same surfaces moved behind
+`(hover: hover) and (pointer: fine)`, which is #68's gate applied to a
+tint rather than to a revealed control.
+
+**`touch-action: manipulation` was considered and not taken.** The
+Findings offer it for the 300ms tap delay; this app's viewport is
+`width=device-width`, which is what removes that delay in Chrome, so
+the stated benefit is not there to win. What it would change is the
+gesture stack #63 tuned by measurement on the device (`pan-y` plus a
+non-passive `preventDefault`), and that is not measurable from here.
+
+## Art pop-in is measurable in a browser, if you count frames rather than milliseconds (measured 2026-08-24)
+
+#65 is an Android report ("scrolling through albums, the art pops in")
+and the desktop harness can measure it, which was not obvious: the
+first attempt waited 220 ms after each scroll jump and found **zero**
+blank covers on either build. The metric only discriminates at one and
+two animation frames after the jump, which is where a pop-in actually
+lives.
+
+Protocol, on `make dev-headless SEED=bulk` (4 988 albums), ten
+2 400px jumps of `.grid-scroll-container`, counting covers whose rect
+intersects the viewport with `naturalWidth === 0`:
+
+| build | blank at frame 1 | at frame 2 | at 50 ms |
+|---|---|---|---|
+| `main` | 254 / 258 | 214 / 258 | 0 |
+| `main`, second run | 254 / 258 | 190 / 258 | 0 |
+| prefetch | 117 / 258 | 77 / 258 | 0 |
+| prefetch, second run | 118 / 258 | 96 / 258 | 0 |
+
+Two things this protocol gets wrong if repeated carelessly. **A second
+run in the same browser session measures the HTTP cache**, not the
+build — the skill already warns about this for `make perf`, and it
+applies to any image measurement; every row above is a fresh
+`playwright-cli close` + `open`. And **the frontend is embedded**, so
+comparing builds is a `git stash` *and* a rebuild, not a stash.
+
+**The bulk library's covers are 300x300 and ~3.7 kB**, which is why
+both builds are clean by 50 ms here and why the phone's number cannot
+be inferred from this one — same caveat the skill already records
+about full-size artwork.
+
+**`rangeChanged` and `visibilityChanged` are different ranges**, and
+the difference is the whole of this fix's value.
+`@lit-labs/virtualizer` reports `_first`/`_last` (rendered, including
+the ~1000px overhang) on the former and `_firstVisible`/`_lastVisible`
+on the latter. Both grids listen to `visibilityChanged` for scroll
+persistence, which wants the visible range and is correct; a prefetch
+window measured from it lands mostly on cards that already exist.
+Anchored there, the component test could see only one row past the
+last rendered card.
+
+**`_overhang` is not configurable.** It is a `protected` field set to
+1000 in `BaseLayout` and read by every layout; there is no option on
+`grid()`/`flow()` and no property on the element. The issue's Direction
+("ask the virtualizer for a larger overscan") is therefore not
+available without patching a private, which is why the request is
+issued ahead of the element instead.

.planning/plans/completed/019-android-touch-model.md

@@ -0,0 +1,408 @@
+# 019 — The Android touch model
+
+**Issue:** #63 (`Area/Library-UI`, `Kind/Feature`, `Priority/High`)
+**Depends on:** #60 (bottom-sheet menus) — closed, merged as PR #176
+**Relates:** #67 (inline links into the menu), #71 ("More" nav), #54
+(native feel), #5/#8 (selection, drag to queue — the desktop semantics
+being diverged from)
+**Status:** shipped (phases 1-4). Its one deliberate remainder is #200.
+
+#73 puts #60 first in Phase 4 because it is "the presentation every
+other item needs", and this is the next one. The Direction on #63 asks
+for the interaction model to be designed as one piece before any of it
+is built, because it *reassigns an existing gesture* rather than adding
+one — `utils/long-press.ts` currently owns the 500ms hold, and every
+context menu in the app is downstream of it.
+
+This document is that design. Everything below is a measurement, or an
+argument for one of the choices #63 leaves open.
+
+---
+
+## The mapping
+
+| gesture | pointer is a finger | pointer is a mouse |
+|---|---|---|
+| single tap / click | **play the row** | select the row |
+| double | — | play the row |
+| long press (500ms) | **enter selection mode** | — |
+| right-click | — | context menu |
+| swipe right | **add to queue** | — |
+| drag | reorder / drag to playlist | reorder / drag to playlist |
+
+Three of those are #63's report unchanged. Two are decisions it left
+open, and one is a deliberate divergence.
+
+---
+
+## Decision 1 — the predicate is the pointer, not the platform
+
+#63 says "the row component needs a platform-aware interaction layer
+rather than shared handlers". It needs an interaction layer; it should
+not be platform-aware.
+
+**The question a row has to answer is not "am I on Android" or "is the
+viewport under 600px" but "what made this event".** `pointerType ===
+'touch'`, read off the event that is being handled, which is already
+how `long-press.ts` decides (`if (e.pointerType !== 'touch') return`)
+and is the only such test in the frontend today.
+
+This is #64's rule — the predicate is named after the capability, not
+the platform — and it carries #64's warning with it. Keyed on a width:
+
+- an Android **tablet** at 600px or more gets click-selects /
+  double-click-plays on a touchscreen, which is the exact inversion
+  this issue exists to fix, on the platform it exists for;
+- a **touchscreen laptop** cannot be described at all, because both
+  pointers are live in the same session on the same row;
+- and a narrow desktop window gets phone semantics with a mouse.
+
+Per event, all three are right for free, and there is no second
+declaration of what a phone does — the thing CLAUDE.md declines to add
+every time it comes up.
+
+**Measured, so this is not an assumption about the WebView.** On the
+reference device (TLP301, Android 14, WebView Chrome 113, 424x439),
+driving a real tap with `adb shell input tap`:
+
+```
+[["down","touch",78,94],["touchstart","touchstart",0,0],["up","touch",78,94]]
+```
+
+`PointerEvent` exists, `pointerType` is `"touch"`, `maxTouchPoints` is
+5, and `(pointer: coarse)` / `(hover: none)` both match.
+
+---
+
+## Decision 2 — there is no double-tap, and the number is why
+
+#63 asks for *single tap → play* **and** *double tap → context menu*.
+Those two cannot both be honoured. The first tap of a double tap is
+indistinguishable from a single tap until the interval expires, so
+"tap plays" necessarily becomes "tap waits to find out whether you
+meant something else, then plays". The app already owns that constant:
+`utils/explore-link.ts` holds a navigation for `DOUBLE_CLICK_GRACE_MS
+= 250` for precisely this reason.
+
+**What it would be added to, measured on the device.** Six runs, from
+the play command to the backend's `TrackChanged`:
+
+```
+155, 123, 85, 56, 91 ms          median ~100
+```
+
+So the app's primary interaction is ~100ms, and a double-tap
+discriminator makes it ~350 — **3.5x, of which 250ms is spent
+deliberately doing nothing** — paid on every track anyone ever plays,
+in order to reach a menu.
+
+It is also against the platform's convention, which counts for more
+than usual here because this is the phone build and nothing else:
+long-press is *how you select* on Android (Gmail, Files, Photos),
+double-tap is zoom or nothing, and a list's menu is either the
+long-press sheet or a per-row overflow.
+
+**So the menu and the selection action bar become the same surface**,
+which is the convention and removes a concept rather than adding one.
+Long-press selects the row it was made on and raises the action bar;
+the bar's actions *are* the context menu's actions, contextualised to
+whatever is selected — one row or forty. #60's bottom sheet stays
+behind it as the overflow, so `contextMenuStyles`, `MenuKeyboard` and
+`menu-surface` are reused rather than reimplemented.
+
+---
+
+## Decision 3 — tap-to-play and selection mode ship together
+
+The obvious phase order is "tap plays first, it is the smallest
+change". It is wrong, and the reason is a capability that exists today
+and is easy to miss.
+
+**A touch user can already multi-select**: tap selects (the desktop
+semantics, which a finger currently gets), and the long-press menu then
+acts on the selection. Move tap to play without shipping selection mode
+in the same change and there is a window — a release, if it lands — in
+which selecting forty tracks to add to a playlist is impossible on a
+phone. That is a regression dressed as an increment.
+
+So phase 1 is both, or neither.
+
+---
+
+## What the code looks like now
+
+| surface | how it binds | selection |
+|---|---|---|
+| `track-list` | delegated on the virtualizer: `click`, `dblclick`, `contextmenu`, `dragstart` | `SelectionController` |
+| `queue-panel` | delegated, same shape | `SelectionController` |
+| `playlist-details` | per row | `SelectionController` |
+| `smart-playlist-details` | per row | `SelectionController` |
+
+All four already share `SelectionController`, and all four resolve a
+row from an event by `data-index` / `data-file-path` on the row. So the
+gesture layer has one shape to talk to, and "selection mode" is a flag
+on the controller they already have rather than a fifth concept.
+
+`utils/long-press.ts` is one document-capture listener that synthesises
+a `contextmenu` — the seam that needed no component to opt in. **This
+plan keeps that shape and changes what the gesture means**, which is
+why it is a rewrite of that file rather than a second listener set: two
+document listeners both claiming the 500ms hold is the fault the file's
+own header warns about.
+
+---
+
+## Two measurements that decide the implementation
+
+**`touch-action` is `auto` on both the virtualizer and the rows.** With
+`auto` the browser owns panning on both axes, so a horizontal drag can
+be claimed as a scroll and our gesture ends in `pointercancel`
+mid-swipe. A row that wants a horizontal swipe has to declare
+`touch-action: pan-y`: the browser keeps the vertical pan (which is the
+virtualizer's scroll, and must stay native or the list stutters) and
+hands us the horizontal axis. This is the single most likely way for
+swipe-to-queue to "work in Chromium and not on the phone".
+
+**The row is 424x52 on the device**, so a swipe threshold in px is a
+fraction of a row height, not of a screen.
+
+**And the third one was found by building phase 1 and then running it**
+— it is not something any browser tier can report. Chrome 113's Android
+WebView **fires its own `contextmenu` on a long press**. `long-press.ts`
+stood down when a trusted one arrived, which was right while both paths
+ended in the same place; once a hold can mean selection mode they end
+in different places, and standing down means the gesture silently does
+the *old* thing. Measured, before the fix:
+
+```
+{"log":["contextmenu isTrusted=true"],
+ "state":{"bar":null,"menuActive":true,"selected":1}}
+```
+
+`yj-long-press` was never announced at all, the context menu opened,
+and all 26 tests in the component tier passed — dispatched pointer
+events do not make a browser synthesise a `contextmenu`.
+
+So the browser's event is a **trigger, not a competitor**: the gesture
+is announced from it, and only a component that claims it suppresses
+the native menu. Unclaimed, it propagates untouched. That is the same
+"browser wins" outcome, reached by asking instead of assuming — and
+verified both ways on the device, a track row entering selection mode
+and an album card still opening its menu.
+
+The tier could not *find* it and can *hold* it: a test cannot dispatch
+a trusted event, but this module has always told its own apart by
+identity rather than `isTrusted`, so an untrusted one from a test takes
+exactly the browser's path.
+
+---
+
+## A tier note: this one can be driven, not only measured
+
+`adb shell input tap|swipe` reaches the WebView as real pointer events,
+which the log above is evidence of. So for the first time the Android
+tier can *perform* the thing under test rather than describe the page
+afterwards — a long press is `input swipe X Y X Y 600`, a swipe right
+is `input swipe X Y X+N Y 120`.
+
+Device CSS pixels from device pixels, on this phone:
+`css = (device - 59) / 2.564` vertically, `css = device / 2.564`
+horizontally (measured from the tap above: 200,300 arrived as 78,94).
+
+This does not make the device a spec tier — it does not run in CI and
+`make ui-test` still has to carry the assertions. It makes "does the
+gesture actually fire on Chrome 113" answerable in seconds.
+
+---
+
+## Phases
+
+**Phase 1 — the seam, tap-to-play, selection mode.** `utils/
+touch-gestures.ts` replacing `long-press.ts`: pointer-typed
+recognition of tap / long-press / horizontal swipe, dispatched as
+composed custom events so a delegated listener in any shadow root
+still works. `SelectionController` gains a mode. `track-list` acts on
+tap and enters the mode on long press. The action bar.
+
+**Phase 2 — swipe right to queue**, with the `touch-action: pan-y`
+finding above and a reveal-and-snap affordance. **Shipped**; what the
+device said about it is the section below.
+
+**Phase 3 — the other three surfaces**, which is mostly wiring, since
+they already share the controller. **Shipped**, and it was not entirely
+wiring — see below.
+
+**Phase 4 — what this leaves behind.** The inline `explore-link`s in a
+row are a single-click target inside a row whose single tap now plays;
+that conflict is #67's, and this plan should not pre-empt its answer
+beyond making tap-to-play win on touch. **Shipped.**
+
+## Phase 3 was not symmetric, in two places
+
+**A tap on a queue row plays that position**, not the list. Copying
+`track-list`'s tap — which sets the queue to the list the row is in —
+would rebuild the queue *from* the queue, discarding its source, its
+shuffle order and everything a user had inserted by hand. It reads as a
+no-op and is not one.
+
+**The queue panel has no swipe, deliberately.** A right swipe means
+*add to the queue* everywhere else it exists, and a queue row is
+already in the queue; the only thing it could mean there is *remove*,
+which is the same gesture with the opposite effect one screen away —
+the fault `utils/icon-language.ts` exists to have fixed for glyphs.
+Removing a queue row is on the row itself (the ×), on its bottom sheet
+since #60, and on the selection bar this phase gave it. The assertion
+is that its rows do **not** carry `data-swipe`, so a swipe there cannot
+silently become a second meaning for the app's one horizontal gesture.
+
+And the affordance became `utils/swipe-to-queue.ts` rather than being
+copied twice. Three lists want it; three copies of "how far is far
+enough" is three chances for them to disagree, which is what
+`utils/library-status.ts` and `utils/ownership.ts` each exist to have
+stopped happening. The shared stylesheet is keyed on `[data-swipe]`
+rather than on a class name, because the three lists call their rows
+two different things and the `touch-action` half of the device fix has
+to reach all of them.
+
+## Phase 4 was already true, which is why it is asserted
+
+A claimed tap has its click swallowed at document capture, so an
+`explore-link` inside the row never sees one and tap-to-play wins with
+no rule of its own. Nothing in the suite would have failed if that
+stopped covering the link, and the symptom — tapping a track's *title*
+navigating to its album instead of playing it — is one a phone user
+meets constantly and a mouse user never does.
+
+**Its test was vacuous when written**, in the way this file keeps
+finding: the tap helper dispatched `pointerdown` and `pointerup` and no
+`click`, so there was nothing to swallow and the assertion held on any
+build. It sends the trailing click now, which also strengthened phase
+1's "a tap plays and does not also select". The fixture needed an MBID
+for the same reason — without one the link asks the backend for a local
+album first and gives up when nothing answers, so "it did not navigate"
+was true of a working build and a broken one alike.
+
+---
+
+## What phase 2 measured, which was not what phase 2 predicted
+
+The `touch-action` finding above is **half** of the answer, and
+shipping only that half would have been the exact failure it warns
+about. Driving a real finger with `adb shell input swipe` across a
+track row, three values, all three on the device:
+
+```
+touch-action: auto    pointerdown, 1 move,  pointercancel
+touch-action: pan-y   pointerdown, 2 moves, pointercancel
+touch-action: none    pointerdown, 2 moves, pointercancel
+```
+
+`touchmove` kept firing in all three. So **Chrome 113's WebView
+cancels the pointer stream ~16px into any drag whatever `touch-action`
+says**, and a swipe recognised from `pointermove` — which is what the
+rest of this module is built on — is a swipe that dies 16px in.
+
+The other half is a **non-passive `touchmove` calling
+`preventDefault()`**: with it, the same swipe ran to 12 moves and a
+`pointerup` at full travel. And both halves are required, which was
+measured rather than assumed — with the `preventDefault` in place and
+`touch-action` back at `auto`, the gesture died after **one** move.
+The reading is that `auto` lets the browser commit to a horizontal pan
+on the first move past slop, before any threshold of ours can have
+been crossed, while `pan-y` leaves it undecided long enough for the
+second move to claim it.
+
+`none` is the one value to avoid: the list stopped scrolling at all.
+With the shipped pair, a vertical drag still scrolls the virtualizer
+81px on the same run that a horizontal one survives.
+
+**`draggable="true"` is not a competitor**, which is the other thing
+the device was asked. No `dragstart` fires from a touch drag on this
+WebView at all, so the drag-to-playlist attribute on every row needs no
+pointer-type gate.
+
+### And it found a phase 1 defect that no tier can see
+
+The native `contextmenu` arrives in **either** order, and phase 1 only
+handled one of them. `nativeSeen` covers the browser's menu arriving
+*during* the hold. The reverse — our 500ms timer firing first, a
+component claiming it, and Chrome delivering its own `contextmenu`
+50–70ms *later* — was suppressed by nothing, so the context menu
+opened on top of the selection bar. Measured over four holds:
+
+```
+hold 1  yj-long-press, then contextmenu isTrusted=true   menu open
+hold 2  yj-long-press                                    clean
+hold 3  yj-long-press, then contextmenu isTrusted=true   menu open
+hold 4  yj-long-press                                    clean
+```
+
+Two in four, on the one surface #63 exists to have changed, and
+invisible to both browser tiers because neither synthesises a
+`contextmenu` from a dispatched press. A press that has produced its
+outcome now suppresses a late one whichever branch it took; six holds
+on the fixed build, six clean.
+
+### The rules phase 2 settled
+
+- **A swipe is not a selection.** It queues the row it was made on,
+  unless that row is one of several *explicitly* selected — the same
+  rule the context menu answers with, because a bar reading "40
+  selected" beside a gesture that quietly queues one of them is two
+  answers to one question. It never changes the selection, which is
+  where it differs from a right-click.
+- **Rightward only.** Nothing is bound to a leftward swipe and
+  claiming one would take a gesture away to do nothing with it.
+- **The commit threshold is a fraction of the row** (0.3, floor 72px),
+  because the row is 424x52 on this device and a bare pixel count is a
+  fraction of a row height on one screen and a third of the width on
+  the next.
+- **The affordance is not only a colour** (WCAG 1.4.1, the rule the
+  playing-row marker exists for): the pane carries the queue icon and
+  words, the words change at the threshold ("Add to queue" → "Release
+  to add" → "Added"), and the outcome is announced in a live region.
+- **The row does not move; its cells do.** `.track-row` is
+  `contain: strict` with `overflow: hidden`, so a pane held at the
+  row's original position while the row translates is a pane at a
+  negative offset inside a clipping box and is simply not painted.
+  Sliding the cells needs no wrapper element in a row that is already
+  a grid.
+- **The travel is written to the row's own style, not rendered.** One
+  render at the start, one at the threshold, one at the end; a
+  virtualizer re-rendering every visible row per frame of one finger's
+  travel is the thing `perf.m1` is about.
+
+## Open questions
+
+1. **Does selection mode have an escape other than the bar's own
+   close?** *Settled: Escape, here; back, not here.*
+
+   Escape leaves the mode, from `selection-bar` rather than from each
+   of the four hosts — that element exists only while the mode does, so
+   it is the one place a dismissal can be attached and detached with
+   the thing it dismisses. It is the same documented exception the
+   overlaid queue's Escape is: **a dismissal, not a shortcut**, so it
+   is not a panel-scoped binding.
+
+   The back gesture is the half that is *not* done, and deliberately.
+   The obvious version — `selection-bar` pushing a history entry — is
+   precisely the fault `navStack` was deleted for: the shell owns the
+   stack (#6/#55) and is the only thing that calls `pushState`, so that
+   two stacks cannot disagree about what one press means. Four lists
+   each reaching for `history` is four stacks. It is also wrong on its
+   own terms, since a mode is per-component and a user who enters one,
+   navigates away and returns has an entry for a mode that no longer
+   exists. #55 settled the shape for a *place*; a mode is not one,
+   which is why it could not simply inherit that answer.
+
+   What it wants is one shell-owned register of dismissible surfaces,
+   which would retro-fit the queue overlay, the dialogs and this alike
+   rather than adding a fourth private answer. **#200.**
+
+2. **Does a tap on a row's favourite icon still toggle it in normal
+   mode?** *Settled in phase 1: yes.* A control inside the row keeps
+   its own tap — the gesture is simply not claimed there, so the click
+   behind it falls through untouched. It is the same rule the shortcut
+   service has for a focused control that owns a key, and it is what
+   keeps the 44px favourite target (#56) from becoming a 44px play
+   target. The queue row's × is the second instance of it.

CLAUDE.md

@@ -6,6 +6,22 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 YellowJacket is a cross-platform desktop music player built with Go (backend) and TypeScript/Lit (frontend), using the Wails framework to bridge them. It supports MP3, FLAC, OGG Vorbis, and WAV playback.
 
+**The three prose documents are split by reader, not by topic** (#50).
+`README.md` is the landing page and answers *a user's* questions only —
+what it does, which channel installs it on which platform, where its
+data lives — with three screenshots in `docs/images/`, captured from the
+fixture library (`make sandbox-seed NAME=default` → `make dev-headless
+SEED=default`) so they can be retaken by anyone. `CONTRIBUTING.md` holds
+what used to be the second half of that README — prerequisites, the
+system libraries, the build and codegen commands, which verification
+tier a change demands, the tracker workflow and the commit grammar. This
+file stays the deep reference both of them point at, and is the only one
+of the three that explains *why* a shape is what it is. A fact that
+belongs to a user goes in one place; the packaging channels keep their
+own documents (`packaging/*/README.md`, `docs/android-release.md`) and
+are linked rather than summarised, because a version-restart note copied
+into the README is a second copy to keep true.
+
 ## Issues
 
 **The tracker is the source of truth for what is wanted and what is
@@ -262,6 +278,26 @@ real store code. A binding carries an **ID**, not a name
 `yellowjacket/backend/home.Service.GetShelves`), so the fake derives
 that map from the generated tree rather than writing it down.
 
+**A test file does not get its own origin, so `setup.ts` clears
+`localStorage` between tests.** `@vitest/browser-playwright` opens one
+BrowserContext per session and runs several files in it one after
+another, so everything a component persists — the track list's sort and
+column widths, the cover size, `now-playing`'s scroll mode — is still
+there when the next file mounts the same component. Which files share a
+tab, and in what order, changes run to run, so the symptom is a spec
+that fails about one test in three and passes every time it is run on
+its own: #138 cost three scheduled runs, one of them a PR whose diff
+held no frontend code at all. Measured on the build before the fix, a
+single full run started **24** tests with storage already set. Two
+things follow. The clear is safe precisely because the leak is
+sequential — files in a session do not overlap, so it cannot wipe
+storage a concurrently-running file is in the middle of using — and it
+belongs in `setup.ts` rather than in the specs that write, because the
+spec that *reads* is never the one that knows. And a spec whose
+assertion depends on an order still **states that order** rather than
+inheriting a default, or the next change to a default is the same
+mystery again.
+
 **`frontend/bindings/` is generated by `wails3`, not `go generate`**, so
 the pre-commit codegen check does not cover it. `make bindings-check`
 (~3.5 s warm, ~20 s on a cold build cache, also a pre-commit hook)
@@ -1093,9 +1129,9 @@ not the fix and cannot be: that function is the `document` listener for
 `navigate`, so it is an infinite loop.
 
 **It is a store rather than an event, because a component that mounts
-after a navigation still has to know.** `bottom-nav`'s "More" drawer
+after a navigation still has to know.** `bottom-nav`'s "More" sheet
 creates its `<app-sidebar>` on open, and that copy had heard no
-`navigate` at all — standing on Albums, the drawer opened highlighting
+`navigate` at all — standing on Albums, it opened highlighting
 Home. An event has no answer for a listener that was not there.
 
 **A detail view is not a view here**, so the destination it was opened
@@ -1196,7 +1232,7 @@ and then vanishing.
 than a general rule about phones.** `PHONE_COLUMN_IDS` is the precedent
 for "what a phone shows is a different question", and it would apply —
 except that `bottom-nav`'s "More" opens the *same* `<app-sidebar>`,
-which filters, so an unfiltered bar would contradict its own drawer one
+which filters, so an unfiltered bar would contradict its own sheet one
 tap away. Which four tabs is still plan 016's committed subset; this
 only removes from it, and "More" is never filtered because it is how
 everything else stays reachable.
@@ -1402,7 +1438,7 @@ descendants. On the reference device the main panel spans 0-318 of a
 items cut off, with no way to reach them. `showModal()` is Chrome 37
 and uses the real top layer, so a dialog is immune by construction.
 
-Six things about it are load-bearing.
+Seven things about it are load-bearing.
 
 **"Dialogs are fine" needed checking, because every other dialog in
 this app is mounted in `index.html`** — outside `.main-panel` — so it
@@ -1431,6 +1467,47 @@ doing nothing, which reads as the gesture breaking. `menu-dismiss` is
 that signal; the three surfaces that do not use `ContextMenuController`
 bind it themselves.
 
+**A sheet that scrolls says so, and `background-attachment` is what
+asks whether it does** (#207). The sheet is capped at 85vh — a surface
+covering the whole screen is a page, not a sheet — so a long menu's
+body scrolls, and for three phases it scrolled *silently*: measured at
+424x439, eight items ended at y=470 with the fold at 439, and where the
+cut lands on a row boundary the sheet ends in a clean edge that reads
+as the end of the list. The fade is two background layers on
+`wa-dialog::part(body)` — a shadow pinned to the box (`scroll`) under a
+cover of the sheet's own colour painted at the end of the *content*
+(`local`), which scrolls up over the shadow exactly when there is
+nothing more to see. So it is absent on a menu that fits, present the
+moment one does not, and gone again at the end of the list, with no
+scroll listener and nothing reaching into `wa-dialog`'s shadow root for
+the scroller. **The curve is steep because the rows under it stay
+live**: a scrim over a menu item is that item's text surface, and the
+4.5:1 rule applies to it — 32px already down to a quarter strength at
+14px spends its weight below the last legible label, measured at 9.9:1
+on the light ramp, whose `bgElevated` is `#e9ecef`.
+
+**And the phone has two sheets, so that rule is one file both read**
+(#210). `bottom-nav`'s "More" is capped at the same 85vh and overflows
+for the same reason — measured at 424x439 with eight destinations,
+`scrollHeight` 412 against `clientHeight` 373, and eleven items at 48px
+would be 528, since #25 makes the count the user's. So the two layers
+live in `styles/sheet-scroll.css.ts` and each host says only what is
+local to it: the colour, handed over as `--yj-sheet-surface` on the same
+box, because the nav sheet paints the sidebar's `--yj-bg-surface` and
+the context sheet the menus' `--yj-bg-elevated` — a shared rule that
+hard-coded either would draw that seam across the other one.
+
+The half that is not the fade is what makes it visible: **nothing inside
+the sheet may repaint the surface**, because these are background layers
+on the scroller and an opaque child covers them. `menu-surface` already
+had it from the other side (`.context-menu-panel[data-sheet]` is
+`background-color: transparent`); `app-sidebar`'s host paints
+`--yj-bg-surface`, which in the shell is its own background and in the
+sheet is a second copy of the sheet's, so `bottom-nav` turns it off.
+Measured at 424x439 with the fade adopted and that rule missing: a flat
+52,58,64 to the bottom edge with 39px still below, which is the defect
+unchanged and every assertion about `background-attachment` passing.
+
 **The playlist submenu is a sheet too, and it had to be.** It is a
 `placement="right-start"` flyout, and making the menu full-width moved
 its anchor — measured at x −182 to 0, entirely off-screen, so "Add to
@@ -1449,18 +1526,112 @@ never opens). **The sweep found two of the fourteen**; twelve were
 converted by hand.
 
 **And a menu opens from a finger, through the event it already has.**
-`utils/long-press.ts` is one document-capture listener installed once
+`utils/touch-gestures.ts` is one document-capture listener installed
-from `index.ts`: a touch that holds still for 500 ms dispatches a
+once from `index.ts` — `utils/long-press.ts` until #63 replaced it,
-synthetic `contextmenu` at the touch point, so all six components that
+rather than adding a second listener claiming the same 500 ms hold. It
-bind one — delegated on a virtualizer, per row, per card — gained the
+**announces** rather than acts: `yj-tap`, `yj-long-press` and
-gesture without changing. The target is `composedPath()[0]` rather than
+`yj-swipe-start` are composed and cancelable, and a component claims
+one with `preventDefault()`. That is what let #63 reassign the hold
+without touching one of the fourteen context menus: an *unclaimed*
+`yj-long-press` still becomes a synthetic `contextmenu`, so all six
+components that bind one — delegated on a virtualizer, per row, per
+card — behave exactly as they did, and only the lists that opt in get
+selection mode. The target is `composedPath()[0]` rather than
 `elementFromPoint`, which stops at the outermost shadow host and so
-reaches a delegated listener and no per-row one; a browser that fires
+reaches a delegated listener and no per-row one; and the click that
-its own long-press `contextmenu` (Chromium does, WebKit and the WebView
+ends a *claimed* gesture is swallowed, keyed on the gesture rather than
-vary) wins, ours being told from theirs by **identity** rather than
+on a time window so the first tap on the menu it opened is not eaten
-`isTrusted`, since no test can dispatch a trusted event; and the click
+too.
-that ends the gesture is swallowed, keyed on the gesture rather than on
+
-a time window so the first tap on the menu it opened is not eaten too.
+Three things about it are load-bearing, and all three were found on the
+device rather than in a tier.
+
+**A browser that fires its own long-press `contextmenu` is a trigger,
+not a competitor.** Chromium does, WebKit and the WebView vary. The old
+rule was to stand down when a trusted one arrived, which was right
+while both paths ended in a context menu and is wrong the moment a hold
+can mean something else — standing down silently does the *old* thing.
+So the gesture is announced from the native event, and only a component
+that claims it suppresses that event. Ours and the browser's are told
+apart by **identity** rather than `isTrusted`, since no test can
+dispatch a trusted event.
+
+**That arrives in either order, and both have to be handled.** The
+native `contextmenu` mid-hold is one case; the other is our own 500 ms
+timer firing first and Chrome delivering its menu **50–70 ms later**,
+which nothing suppressed — measured over four holds on the reference
+phone, two took that order, so the context menu opened over the
+selection bar intermittently, on the one surface #63 changed. A press
+that has produced its outcome therefore suppresses a late
+`contextmenu` whichever branch it took.
+
+**A horizontal swipe runs on touch events, and needs two things that
+look like one.** Chrome 113's WebView cancels the *pointer* stream
+~16 px into any drag — measured at `auto`, `pan-y` and `none` alike,
+one or two `pointermove`s and then `pointercancel`, while `touchmove`
+kept firing throughout. So the recogniser is `touchmove`, the surface
+declares **`touch-action: pan-y`** *and* a claimed swipe calls
+**`preventDefault()`** on a non-passive listener. Neither works alone:
+with the `preventDefault` in place but `touch-action` back at `auto`
+the gesture died after one move, because `auto` lets the browser commit
+to a horizontal pan before any threshold can be crossed. `none` is the
+value to avoid — it takes the list's own vertical scrolling with it.
+**Both are correct in Chromium either way**, which is why this is
+written down rather than tested. The tie breaks toward scrolling, in
+that order: vertical drift past the tolerance vetoes the swipe for the
+rest of the press (a scroll that curves is still a scroll), and a
+gesture that is not *strictly* more horizontal than vertical is the
+scroller's.
+
+**And what a finger *means* on a row is the inversion of what a mouse
+means, decided per event** (#63). A click selects and a double-click
+plays; a tap **plays** and a hold enters **selection mode**, in which a
+tap toggles. The predicate is `pointerType`, never a viewport width and
+never a platform flag — #64's rule, and with #64's warning: keyed on a
+width, an Android tablet over 600px gets desktop semantics on a
+touchscreen, a touchscreen laptop cannot be described at all, and a
+narrow desktop window gets phone semantics with a mouse.
+
+There is deliberately **no double-tap**, which #63 asked for. The first
+tap of one is indistinguishable from a single tap until the interval
+expires, so tapping would have to wait `DOUBLE_CLICK_GRACE_MS` before
+acting — 250ms on top of a measured ~100ms play, 3.5x the app's primary
+interaction, to reach a menu a hold already reaches. So the menu and
+the action bar are the same surface: `components/selection-bar/` is
+presentational (a count and a list of actions, no store, no selection),
+`SelectionController` carries the mode for all four selecting surfaces,
+and #60's bottom sheet is the overflow behind "More" — so
+`contextMenuStyles`, `MenuKeyboard` and `menu-surface` are reused
+rather than reimplemented.
+
+Three things about it are load-bearing. **A control inside a row keeps
+its own tap**: the gesture is simply not claimed there, so the click
+behind it falls through, which is what stops the 44px favourite target
+(#56) becoming a 44px play target — the queue row's × is the second
+instance. **A swipe right queues**, and its affordance is
+`utils/swipe-to-queue.ts` once rather than in each of the three lists
+that draw it: the row does not move, its *children* do (a row here is
+`contain: strict` with `overflow: hidden`, so a pane held at the row's
+original position while the row translates is at a negative offset
+inside a clipping box and is not painted), the travel is written to the
+row's own style rather than rendered, and the threshold is a fraction
+of the row because the row is 424x52 on the reference device. **The
+queue panel takes the tap and the hold and refuses the swipe**, because
+a right swipe means *add to the queue* everywhere it exists and a queue
+row is already in it — the only thing it could mean there is *remove*,
+which is the same gesture with the opposite effect one screen away.
+A tap there plays that *position*, too: setting the queue to the queue
+reads as a no-op and discards its source, its shuffle order and
+anything inserted by hand.
+
+Escape leaves the mode, from `selection-bar` rather than from each
+host, since that element exists only while the mode does — the same
+exception the overlaid queue's Escape is, *a dismissal, not a
+shortcut*. The platform's back gesture deliberately does **not** reach
+it: the shell owns the history stack and four lists each reaching for
+`history` is four stacks, which is the fault `navStack` was deleted
+for. That wants one shell-owned register of dismissible surfaces, which
+is #200.
 
 **A control revealed by `:hover` is gated on the device having hover,
 and which way round depends on whether it is the only route to its
@@ -1498,6 +1669,51 @@ sits inside which media query — and says so; the regression it exists
 for is someone hoisting a rule out of its query as a tidy-up, which
 nothing on a desktop renders differently.
 
+**The web view's own tap highlight is gone, and what replaced it is a
+press state** (#54). `-webkit-tap-highlight-color` is an *inherited*
+property, so one declaration on `html` in `index.css` reaches every
+shadow root in the app and takes away the grey box a phone drew over
+the bounding rect of whatever was tapped — measured at
+`rgba(0, 0, 0, 0.18)` with the rule removed. `user-select` is the same
+argument and was already done: `index.css`'s first rule is `*, *::before,
+*::after { user-select: none }`, which reaches the shadow roots for the
+same reason.
+
+Three things about it are load-bearing.
+
+**Removing the highlight removes the only touch feedback several
+surfaces had**, so the press state is part of the same change rather
+than a later polish item: the four lists' rows, `bottom-nav`'s tabs,
+`app-sidebar`'s destinations (which are also the phone's "More" sheet)
+and the shared `contextMenuStyles` menu item all take
+`--yj-press-overlay` on `:active`. The cards already had one
+(`transform: scale(0.97)`) and are untouched.
+
+**A press selector carries a state class or it does nothing where it
+matters.** A row is `.track-row.selected.active`, so a bare
+`.track-row:active` is one class short of it and the press is invisible
+on exactly the row a phone is most likely to press — the one it has
+just selected. The rule is last and lists `.selected:active` /
+`.active:active` beside the bare form.
+
+**And the hover tints on those same surfaces moved behind
+`(hover: hover) and (pointer: fine)`**, which is #68's gate applied to
+a tint rather than to a revealed control and for the same mechanism: a
+hold synthesises a hover in the WebView, so an ungated tint arrives
+because a finger touched the row and stays there after it has gone —
+measured, since with the press rule removed a held row reads
+`rgba(255, 255, 255, 0.05)`, the hover tint, rather than nothing.
+`touch-action: manipulation` was considered and declined: the 300ms
+delay it is offered for is already absent on a `width=device-width`
+viewport, and what it would really change is the gesture stack #63
+tuned by measurement on a device this session cannot measure.
+
+The split of tiers is `hover-affordance.test.ts`'s: `press-feedback.
+test.ts` reads the parsed stylesheet, because `:active` cannot be
+forced there either, and `native-touch-feel.spec.ts` *measures* — it
+holds the button down on a real row of the real list, and it is the
+only tier that loads `index.css` at all.
+
 Three lists had no focused row to open a menu *from* — the queue panel
 and both playlist detail views — and gained a roving tab stop through
 `utils/roving-rows.ts`. **`track-list` deliberately does not use it**:
@@ -1654,6 +1870,21 @@ is not it.** A `placeholder` is an accname fallback, so an
 Explore's search box — the audit's own `a11y.26` — as clean. A sweep
 for *empty* names cannot see a *weak* one.
 
+**`title` is the same trap one rung lower, and it defeats the obvious
+spec as well as the obvious sweep.** `queue-panel`'s Clear queue and
+Add queue to playlist were named by `title` alone, so
+`getByRole('button', { name: 'Clear queue' })` matched them **before**
+the fix as well as after — a `getByRole` assertion, which is what
+catches every other nameless control in this app, would have been
+green on the broken build. `title` is the *last* fallback in the
+accname order, so content put inside the button later silently
+outranks it, and it is the one name a phone cannot show, having no
+hover. The property is therefore asserted as *the name is not the
+tooltip*: `queue-overlay.spec.ts` removes the `title` attributes and
+asks again, which is 1 and 1 with `aria-label` and was measured at 0
+and 0 without it. The `title`s stay, because on a desktop they are
+also the tooltip for an icon-only control and that is a different job.
+
 **The shell scrolls sideways and not down.** `body` is
 `overflow-x: auto; overflow-y: hidden`, and both halves are measured.
 Vertically there is nothing to fix: the middle grid row is `1fr` and
@@ -1696,7 +1927,7 @@ listing the destinations again — but rendering it unconditionally put a
 second copy of every `data-testid="nav-*"` in the DOM, and 30 existing
 specs failed with "strict mode violation: resolved to 2 elements" on a
 desktop viewport where the element is not even visible. It renders only
-while the drawer is open, and `bottom-nav.test.ts` asserts its absence
+while the sheet is open, and `bottom-nav.test.ts` asserts its absence
 before that.
 
 **The tab bar is four destinations and a way to the rest.** Three to
@@ -1705,6 +1936,33 @@ is 32px each. Which four is plan 016's committed subset, and everything
 else — Settings included, because a phone still needs it — is behind
 "More".
 
+**And "More" rises from the bottom, on #60's sheet rather than a
+second one** (#71). It was a `wa-drawer placement="start"`: a 200px
+column of a 424px screen, opening away from the thumb that asked for
+it, with the rest of its 400px band empty. It is the *same element*
+with `placement="bottom"` and `without-header`, which is what keeps
+the change to where it comes from — `wa-drawer` renders a native
+`<dialog>` and opens it with `showModal()`, so #60's containment
+finding carries over with nothing new to prove, and the focus trap,
+Escape, tap-outside and `wa-after-hide` all come along. Measured at
+424x439: 424 wide, 373 tall (85vh, so there is an outside to tap),
+48px rows.
+
+Three things about it are load-bearing. **The sidebar is mounted
+rather than re-listed as data**, which the issue offers as the
+alternative: the shell's own `<app-sidebar>` is `display: none` below
+600px rather than removed, so a second list drawing `nav-*` handles is
+the duplication above, and it would be a second place to add the next
+view to. **There is one scroller, and it is the sheet's body** — the
+reported "only part of the screen scrolls under my finger" is three
+nested ones (the dialog, its body, and the sidebar's own
+`overflow-y: auto` host), so which box a drag moves depends on where
+the finger landed; `overscroll-behavior: contain` is the other half.
+And **`expanded` means the host owns the box, not just the labels**:
+`app-sidebar` writes an *inline* width and caps itself at 400px, which
+beats any rule the host could write, so the width, the scrolling and
+the mouse-only resize handle all follow that attribute.
+
 **There are three supported size bands, and the queue is part of the
 promise.** Plan 018 (#24) wrote them down: **Phone** below 600 (bottom
 nav, reflows, fits 320px exactly), **Compact** 600–899 (icon sidebar),
@@ -2242,6 +2500,31 @@ a list or a detail view:
   and dropped if a second click arrives, because the title is the
   widest thing in a row and double-clicking a row plays it. Rows do
   not need to know links exist.
+
+  **Below 600px a name is not a link, and the row's menu is where it
+  went** (#67). Every sentence above is a *desktop* compromise: the
+  double-click grace means nothing on touch, a few characters of text
+  is not a touch target, and since #63 a claimed `yj-tap` has its click
+  swallowed, so the link was unreachable as well as fiddly. The rule is
+  in the utility rather than at twenty call sites, and
+  `utils/go-to-menu.ts` is the other half — "Go to Artist" / "Go to
+  Album", drawn under exactly the condition the link is not, from
+  `explore-link`'s own exported routing so an untagged artist reaches
+  the library page by the same lookup.
+
+  Three things about it are load-bearing. **Suppressing a link without
+  a menu behind it is not a smaller affordance**, it is a destination
+  the phone cannot reach — so `keepOnPhone` is the documented exception
+  for the three surfaces with no row menu (`now-playing-view`,
+  `explore-album-details`' header credit, `top-results-row`), and
+  nothing else may pass it. **One row or none**: the items are the Play
+  item's rule one step on, since "go to the album" of five different
+  albums means nothing. And **there is no "Go to Genre"**, because
+  there is no genre link anywhere to lose — that would be new
+  navigation rather than a replacement, and belongs in its own issue.
+  `track-list` is the one list that gains rather than moves: its phone
+  column set stacks title over artist as plain text already, so those
+  names have never been links there.
 - **`<catalog-scope-notice>`** is how a detail page admits what it is
   showing: catalog data (silent), a library stand-in while a fetch is
   in flight, library-only because the entity has no MBID, or a failed/
@@ -2455,11 +2738,38 @@ Five things about it are load-bearing, and four of them fail silently:
   correctly. Confidently wrong is worse than absent here, which is the
   same rule `Known` exists for.
 
-One gap this did not close, and it is older: **`dhowden/tag` has no
+One gap this did not close and #104 did: **`dhowden/tag` has no RIFF
-RIFF reader**, so nothing the tag writer puts in a WAV's `id3 ` chunk
+reader**, so nothing the tag writer put in a WAV's `id3 ` chunk was
-is visible to `metadata.ExtractTags` — not the totals and not the title
+visible to `metadata.ExtractTags` — not the totals and not the title
-either. `wav_test.go` reads that chunk itself, which is why no test
+either, on files the app itself had just tagged. `wav_test.go` read
-ever noticed.
+that chunk itself, which is why no test noticed: a round trip asserted
+through the writer's own parser is a test of the writer.
+
+`backend/riff` is where the container is now read, and it is its own
+package because the alternative is an import cycle — `tagwriter`
+imports `metadata`, so `metadata` cannot reach back for `parseRIFF`.
+`backend/tagtotals` is the precedent.
+
+Three things about it are load-bearing. **The two readers are
+deliberately different**: `Parse` holds every chunk in memory, which is
+what rewriting a file needs, and a WAV's audio *is* a chunk — so the
+scan path uses `ID3Chunk`, which seeks over what it is not looking for.
+**The container decides, before `tag.ReadFrom` rather than after it
+fails**, because that library's last resort is an ID3v1 trailer and a
+WAV carrying both would otherwise be read by the wrong one. And **an
+untagged WAV is a file with no tags, not a file with a problem**: no
+chunk, an RF64 container or a tag holding no frames all read as empty
+metadata with no `TagReadWarning`, since the scanner's filename
+fallback is the right answer and a warning would put a fault on a file
+that has none.
+
+The gap was pinned by a test that said so, which failed the moment the
+reader learned and carried the instructions for what to update in its
+own comment. So it is deleted, `TestFixturesMatchManifest` no longer
+skips `wav`, and `totals_test.go`'s WAV case goes through
+`metadata.ExtractTags` like the other three formats. The fixture
+library's two WAV tracks scan with their tags and their cover now,
+which is a change to what every seeded tier sees.
 
 **The absence is what gets marked, not the presence.** The tracklist
 put a green tick against every owned track and a legend underneath
@@ -3146,6 +3456,46 @@ rather than searching it — the store replaces that array when its
 contents change and shares the unchanged members, which is the same
 signal `track-list`'s memoized caches key on.
 
+**And the right tier arriving late still reads as no art at all**, so
+the two grids ask for it before the card exists (#65).
+`utils/image-prefetch.ts` warms the images a scroll is about to reach,
+from `cover-grid`'s and `artists-view`'s virtualizers. Measured on the
+50 000-track bulk seed over ten 2 400px jumps: of 258 covers arriving
+in view, **254 were still blank one frame later and 214 two frames
+later**; with the prefetch, 117 and 77. Both builds are clean by 50 ms
+on a desktop with 3.7 kB fixture covers, which is where the reference
+device's slower engine and 27 kB covers spend their pop-in.
+
+Four things about it are load-bearing.
+
+**The overscan the obvious fix asks for does not exist.**
+`@lit-labs/virtualizer`'s `_overhang` is a hard-coded 1000px
+`protected` field on `BaseLayout` with no configuration surface, so
+raising it means monkey-patching a private. 1000px is about two
+screens on a 439px viewport, and the *image* cannot be requested until
+the card it lives in is rendered — which is what this asks for
+instead.
+
+**It hangs off `rangeChanged`, not `visibilityChanged`.** Those report
+different ranges: visibility is what is on screen, and the virtualizer
+has already rendered that 1000px past it. Anchored to the visible
+range the window is spent on cards that already exist and have already
+asked for their own art — measured as the difference between the
+prefetch reaching one row past the last card and reaching a full
+window past it.
+
+**It is not the `LRUMap` path, and saying so is the bound.** That
+ceiling holds Explore's base64 data URLs in JS; a library cover is a
+plain URL under `Cache-Control: immutable` (the filenames are content
+hashes), so what retains the bytes is the browser's own cache. What
+this module retains is the *set of URLs already asked for*, capped at
+512 and reported to `window.__yjCacheStats()` — 497 entries and 15 407
+chars after the run above.
+
+**The prefetch asks for what the card will draw.** `artists-view`'s
+tier ladder moved into `artistAvatarURL()` so the two cannot disagree;
+a second copy would be a warm cache for a tier nothing renders.
+
 **The same rule, on the selection path, was the worst stall in the
 app.** Five components turned selected file paths back into tracks with
 `filePaths.map(fp => tracks.find(…))`, so "Select all → Edit tags" at
@@ -3330,6 +3680,25 @@ Pre-commit hooks verify generated code is fresh — always run `make generate` a
 Tests use `database.NewTestDB(t)` for in-memory SQLite, built by the same
 `applySchema` production uses so the two cannot diverge. Test audio fixtures live in `test_data/music_library_test/`. Table-driven tests are the norm.
 
+**`make ui-visual` is the one tier nothing but a person runs, and it
+cannot become one.** Its ten `toMatchScreenshot` baselines were recorded
+on a developer's Arch box; replayed in a bare `ubuntu:24.04` container
+— CI's `check` image — three of them fail on font metrics and
+compositing alone (`track-info` and one `page-header` shot at a 0.03
+mismatch ratio against a 0.02 allowance, `seek-bar` one pixel shorter),
+and two components disagree about their own height between the two
+machines. So CI keeps running `make ui-test`, which is the same suite
+with the comparisons off, and a pre-push hook would be the same fault
+with the machines swapped. What replaces the gate is a rule, in
+`.pi/skills/yellowjacket-dev/references/ui-tier.md`: **a change that
+moves a component's geometry refreshes that component's baseline in the
+same commit, having read the image, and never one it did not cause**.
+That is #196, which was four stale references accumulated across three
+unrelated merges — a red tier nobody could read, which is how it stayed
+red. A visual case must also **state the world it photographs**, since
+the stores are singletons and a case that sets nothing records whatever
+the previous one left in them.
+
 ## Git Workflow
 
 Feature branches and PRs are the only way in: **`main` is a protected

CONTRIBUTING.md

@@ -0,0 +1,173 @@
+# Contributing to YellowJacket
+
+This is the contributor's half of the [README](README.md): how to build it, how
+to check a change, and how a change gets in. [`CLAUDE.md`](CLAUDE.md) is the
+deep reference — the architecture, and the reasons behind the shape of it —
+and is worth reading before a change of any size, because most of this
+codebase's traps are written down there and nowhere else.
+
+## Building from source
+
+YellowJacket is [Go](https://go.dev/) with a [Lit](https://lit.dev/)/TypeScript
+frontend, bridged by [Wails v3](https://wails.io/).
+
+| Tool | Version |
+|------|---------|
+| Go | 1.25+ |
+| Node.js | 22+ |
+| pnpm | 10+ |
+| Wails CLI | v3 — vendored, no install needed (`go tool wails3`) |
+
+The Wails v3 CLI resolves from the `tool` block in `go.mod`, so there is nothing
+to install globally; `make setup` fetches it with the rest of the tooling.
+
+On Linux, install the system libraries Wails needs. v3 builds against GTK4 +
+WebKitGTK 6.0 by default:
+
+```bash
+sudo apt-get install libasound2-dev libgtk-4-dev libwebkitgtk-6.0-dev   # Debian/Ubuntu
+sudo pacman -S alsa-lib gtk4 webkitgtk-6.0                              # Arch
+```
+
+A machine without `webkitgtk-6.0` can still build with `-tags gtk3` against the
+older WebKit2GTK 4.1 stack, but that is an escape hatch, not what CI or a
+release builds. macOS and Windows need no extra system packages. Run
+`go tool wails3 doctor` to check your environment.
+
+```bash
+make setup        # install tooling, frontend packages and the git hooks
+make dev          # run with hot-reload
+make build-dev    # debug build with symbols
+make build-prod   # production build (stripped and trimmed)
+make android      # the arm64 APK, into bin/
+```
+
+The `Makefile` is the front door and carries a one-line description against
+each target; `Taskfile.yml` and `build/<platform>/Taskfile.yml` are the build
+implementation behind it and are not called directly.
+
+## Generated code
+
+Two generators run from `go generate ./...`, which `make generate` wraps:
+**sqlc** turns `backend/database/sql/queries/` into Go in
+`backend/database/sql/sqlcgen/`, and **templ** turns `.templ` files into
+`*_templ.go` beside them. Never edit either output by hand — run
+`make generate` after touching a `.sql` or a `.templ` file.
+
+The TypeScript bindings in `frontend/bindings/` are generated by `wails3`
+rather than by `go generate`, so they are a separate step: `make bindings`
+regenerates them and `make bindings-check` fails if they are stale.
+`frontend/src/events.ts` is generated too, from `backend/events/events.go`.
+
+A pre-commit hook checks that all of this is fresh, so the usual way to meet it
+is a failing commit rather than a bug.
+
+## Checking a change
+
+Run the tier the change actually demands, not the cheapest one.
+
+| Change | Command |
+|---|---|
+| Go | `make lint` and `make test` — both cover all three build configurations |
+| A frontend component or store | `make ui-test` (Vitest in a real Chromium, no backend) |
+| A user-visible flow | `make e2e`, against a running `make dev-headless` |
+| CSS | `make css-check` — see the Chrome 113 note below |
+| Anything cosmetic | look at a screenshot; several bugs here were invisible to every assertion and obvious in an image |
+
+`make test` needs the fixture library, which is generated rather than
+committed — it runs `make testdata` itself (about a second).
+
+The end-to-end tier drives the real app with no display at all: `make
+dev-headless` starts it in the background on `:34115` (add `SEED=<name>` for a
+seeded library, built by `make sandbox-seed NAME=<name>`), `make dev-logs` tails
+it and `make dev-stop` stops it. **Check the port before starting one** — if
+`:34115` is already answering, someone else's app is there, and a green result
+about their build is worse than no result.
+
+Two smaller checks exist because the failure they catch is silent:
+`make bindings-check` (stale generated bindings) and `make css-check`, which is
+two passes — one fails on a `css` literal ended early by a backtick inside a
+comment, the other on a nested CSS rule that begins with a bare element
+selector. Chrome 113 is what the reference Android device renders with, and it
+drops such a rule without a word.
+
+`make vulncheck` runs govulncheck over the module.
+
+## The issue tracker is the source of truth
+
+Work is described by issues before it is described by branches, and the tracker
+is shared with people who cannot see your terminal.
+
+- **Search before starting**, closed issues included: `./scripts/issue.sh search
+  <terms>`. "That was fixed three weeks ago" is the cheapest possible answer.
+- **Claim before the first edit**, not before the commit:
+  `./scripts/issue.sh claim <n>` sets the assignee, applies `Status/In Progress`
+  and comments with the branch, so the work is visibly taken *while it is being
+  done*. It refuses if somebody else holds it — talk to them rather than working
+  around it.
+- **If no issue covers the work, open one first** (`./scripts/issue.sh new`).
+- **Findings get filed.** A bug tripped over on the way to something else is an
+  issue with a reproduction, not a wider diff and not a sentence in a chat log.
+- **#73 is the roadmap** and states the order the backlog should be worked in.
+
+`scripts/issue.sh` is the whole interface (`list`, `mine`, `search`, `show`,
+`new`, `claim`, `unclaim`, `comment`, `close`, `label`, `depends`, `labels`) and
+wants a `GITEA_TOKEN` with `write:issue`. The labels are a taxonomy rather than
+tags: `Kind/*`, `Area/*`, `Priority/*`, `Platform/*`, plus `Reviewed/*` and
+`Status/*`, of which the last two are exclusive scopes.
+
+## Commits and pull requests
+
+`main` is protected, so a branch and a PR are the only way in. Branch from
+`origin/main`, and name the branch after the issue (`fix/140-…`, `feat/25-…`).
+
+Commit subjects are [Conventional Commits](https://www.conventionalcommits.org/)
+— `type(scope): subject`, imperative, ≤72 characters — and are enforced by a
+`commit-msg` hook and by CI (`make commit-check`). This is load-bearing rather
+than decorative: semantic-release reads the **type** to decide the next version,
+so a CI-only change is `ci:` and never `fix(ci):`, which would ship a patch
+release. `make release-dry` prints what a release would cut right now.
+
+**The closing keyword goes in the commit body**, one issue per line, because
+Gitea parses commit messages that reach `main` and does not parse the PR body:
+
+```
+docs: rewrite the README as a landing page
+
+<why>
+
+Closes #50
+```
+
+A PR body carries a commit-to-issue table, the verification you actually ran
+(with results), and a `Closes` list for whoever reads it.
+
+## Style
+
+- **Go** — golangci-lint v2, strict: `err113` (static errors), `nlreturn`,
+  `wsl_v5`, `godot`, `sloglint`, `perfsprint`, and imports grouped stdlib →
+  third-party → `yellowjacket/…` by gci.
+- **TypeScript** — strict mode, no implicit `any`, no unused locals or
+  parameters.
+- Match the surrounding code. Where `CLAUDE.md` explains why something is shaped
+  the way it is, that shape is load-bearing and there is usually a test pinning
+  it.
+
+Hooks do most of the enforcing (`lefthook.yml`, installed by `make setup`):
+pre-commit runs vet, lint, the codegen checks, the frontend typecheck and the
+two CSS checks in parallel; pre-push runs the Go suite and the UI tier,
+deliberately one after the other rather than together.
+
+## Where the rest of the documentation is
+
+- [`CLAUDE.md`](CLAUDE.md) — architecture and constraints, in depth.
+- [`docs/PROFILING.md`](docs/PROFILING.md) — Go pprof and frontend profiling.
+- [`docs/android-release.md`](docs/android-release.md) — the APK, its signing
+  key, and what the release workflow checks.
+- [`docs/index-cache.md`](docs/index-cache.md) — the search-index build cache
+  and why it has a snapshot.
+- [`packaging/arch/README.md`](packaging/arch/README.md),
+  [`packaging/homebrew/README.md`](packaging/homebrew/README.md) — the two
+  package channels.
+- `.planning/` — design documents and measured history, not a queue. The queue
+  is the tracker.

Makefile

@@ -160,8 +160,11 @@ ui-watch: ## Same suite, in watch mode
 ui-visual: ## Run the suite including screenshot comparisons
 	@cd frontend && YJ_VISUAL=1 npx vitest run $(UI_ARGS)
 
-ui-visual-update: ## Re-record the screenshot baselines
+# `--update=true`, never a bare `--update`: vitest takes the following
-	@cd frontend && YJ_VISUAL=1 npx vitest run --update $(UI_ARGS)
+# positional as the flag's value, so `--update <path>` swallows the path
+# and re-records every baseline in the repo instead of the one named.
+ui-visual-update: ## Re-record the screenshot baselines (UI_ARGS=<path> to filter)
+	@cd frontend && YJ_VISUAL=1 npx vitest run --update=true $(UI_ARGS)
 
 ui-setup: ## Install the Vitest browser provider's own Chromium (once)
 	@cd frontend && pnpm install && npx playwright install chromium

README.md

@@ -2,112 +2,139 @@
 
 *Music how it was meant to bee.*
 
-YellowJacket is a fast, cross-platform desktop music player for your local
+YellowJacket plays the music you already own. Point it at your folders and it
-collection. It plays your files, keeps your library tidy, and helps you discover
+scans them, reads the tags and the cover art, and gives you a library you can
-and organize your music — all in a clean, responsive interface. No accounts, no
+browse, search, queue and tidy up — on your own machine, with no account, no
-streaming, no telemetry: just your music on your machine.
+streaming service and no telemetry.
 
-Runs on **Linux**, **macOS**, and **Windows**.
+It plays **MP3**, **FLAC**, **OGG Vorbis** and **WAV**, on **Linux** and
+**Android**, and builds from source on **macOS**.
 
-## Features
+![The track list, with something playing](docs/images/library.png)
 
-### Play your music
+## What it does
-- Plays **MP3, FLAC, OGG Vorbis, and WAV**
-- Play, pause, seek, and volume control with a mute toggle
-- Gapless, glitch-free seeking backed by a read-ahead buffer
-- A queue you can add to, reorder, and shuffle, with play-next support
-- Shuffle and repeat (off / all / one)
-- Picks up right where you left off — remembers your track, position, and volume between sessions
-- Media-key and MPRIS support on Linux, so your desktop's playback controls just work
 
-### Keep your library organized
+**Plays your files.** Play, pause, seek and volume with a mute toggle; a
-- Point it at your music folders and it scans them automatically
+read-ahead buffer so seeking is instant rather than gappy; a queue you can add
-- Reads tags and embedded cover art, and de-duplicates artwork so it isn't stored twice
+to, reorder and shuffle, with play-next; shuffle and repeat (off / all / one).
-- Incremental sync — only new or changed files get reprocessed, and deleted files are cleaned up
+It remembers the track, the position and the queue between sessions, and it
-- Browse by **album**, **artist**, or **genre**, or search across everything
+answers your desktop's media keys — MPRIS on Linux, a media notification and
-- Mark favorites and see what you've been listening to with play history
+lock-screen controls on Android.
-- Edit track tags directly when something's off
 
-### Playlists
+**Keeps the library tidy.** It scans the folders you give it and rescans only
-- Create playlists, drag tracks in, and reorder them
+what changed, so a big library costs its full scan once. It de-duplicates
-- **Smart playlists** that build themselves from rules (by genre, rating, play count, and more)
+embedded cover art rather than storing the same image a hundred times, notices
-- Pin a default playlist and spot duplicate tracks at a glance
+files that have gone away, and spots duplicate tracks. Browse by album, artist
+or genre, search across everything, mark favourites, and see what you have been
+playing.
 
-### Discover and clean up (powered by MusicBrainz)
+**Playlists, and playlists that write themselves.** Drag tracks in and reorder
-- **Explore** — browse artists, releases, and genres from the MusicBrainz catalog, not just what's already in your library
+them, or describe what you want — genre, play count, how long since you played
-- **Auto-tag** — match your files against MusicBrainz to fill in correct artist, album, and track metadata, with a review step before anything is written
+it — and let a smart playlist keep itself up to date.
-- **Lyrics search** — find a track by a line you remember
+
+**Explore and auto-tag, from the MusicBrainz catalog.** Explore browses artists,
+releases and genres from the catalog rather than only from what you own, so an
+album page can tell you that you have nine of its twelve tracks. Auto-tag
+matches your files against MusicBrainz and fills in the metadata that is
+missing, with a review step before anything is written to disk. Lyrics search
+finds a track from a line you remember.
+
+Explore needs its catalog, which is a one-off ~0.6 GB download from
+**Settings → Search Index**. It asks first on a metered connection, and
+everything else in the app works without it.
 
 ## Install
 
-Download the latest build for your platform from the
+Every download comes from the
 [releases page](https://git.ljones.me/yonlu/yellowjacket/releases).
 
-| Platform | Download |
+### Linux
-|----------|----------|
-| Linux | `yellowjacket-linux-amd64` |
-| macOS | `yellowjacket-darwin-universal.app.zip` (Apple Silicon + Intel) |
-| Windows | `yellowjacket-windows-amd64.exe` |
 
-Prefer to build it yourself? See [Building from source](#building-from-source).
+Download `yellowjacket-<version>-linux-amd64.tar.gz` from the latest release and
+unpack it. It holds the binary, a `.desktop` entry and an icon.
 
-## Getting started
+On **Arch**, install it from the package registry instead and get updates with
+the rest of your system — the one-time key import and `pacman.conf` block are in
+[`packaging/arch/README.md`](packaging/arch/README.md):
+
+```bash
+sudo pacman -Sy yellowjacket
+```
+
+### Android
+
+Install the APK from the release page, or from the URL below, which always
+points at the newest build:
+
+```
+https://git.ljones.me/api/packages/yonlu/generic/yellowjacket-android/latest/yellowjacket.apk
+```
+
+That URL needs no credentials, so [Obtainium](https://obtainium.imranr.dev/) can
+poll it directly and keep the app up to date. The build is `arm64-v8a` only, and
+[`docs/android-release.md`](docs/android-release.md) says why.
+
+### macOS
+
+Homebrew builds it from source on your own Mac — there is no prebuilt `.app`,
+because a signed macOS bundle needs a macOS machine to produce it and the
+release runner is a Linux container.
+
+```bash
+brew install shadow-puppet/yellowjacket/yellowjacket
+```
+
+See [`packaging/homebrew/README.md`](packaging/homebrew/README.md).
+
+### Windows
+
+Not published. It cross-compiles cleanly, but no Windows build of this app has
+ever been *run*, and nothing here can exercise one — so shipping it would be a
+promise that cannot be kept. You can still build it yourself: see
+[`CONTRIBUTING.md`](CONTRIBUTING.md).
+
+### Coming from a 1.x install?
+
+Versions restarted at **0.0.1** when releases became automatic, which every
+package manager reads as a downgrade. It costs one reinstall, once — the details
+are with each channel: [Homebrew](packaging/homebrew/README.md#upgrading-from-1x-needs-a-reinstall-once),
+[Android](docs/android-release.md#the-1x-installs-cannot-be-upgraded-to-00x).
+
+## First run
 
 1. Launch YellowJacket.
-2. Open **Settings** and add the folder(s) where your music lives.
+2. Add the folder your music lives in — the first-run wizard asks, and
-3. Let the initial scan finish — you'll see progress as it works.
+   **Settings → Libraries** is where you add more later.
-4. Browse by album, artist, or genre, queue something up, and press play.
+3. Watch the scan finish. It reports progress, and you can browse while it runs.
+4. Queue something and press play.
 
-Your library and settings are stored locally:
+Your library and settings stay on your machine:
 
 | | Linux / macOS | Windows |
 |---|---|---|
 | Config | `~/.config/yellowjacket/` | `%LOCALAPPDATA%\yellowjacket\config` |
 | Library data | `~/.local/share/yellowjacket/` | `%LOCALAPPDATA%\yellowjacket\data` |
 
-## Building from source
+Setting `YJ_HOME` moves both, which is how you keep a second library separate.
 
-YellowJacket is built with [Go](https://go.dev/) and a
+## More screenshots
-[Lit](https://lit.dev/)/TypeScript frontend, bridged by the
-[Wails](https://wails.io/) framework.
 
-**Prerequisites**
+An album page knows what you own, and says so:
 
-| Tool | Version |
+![An album page, with two discs and the transport playing](docs/images/album.png)
-|------|---------|
-| Go | 1.25+ |
-| Node.js | 22+ |
-| pnpm | 10+ |
-| Wails CLI | v3 — vendored, no install needed (`go tool wails3`) |
 
-The Wails v3 CLI resolves from the `tool` block in `go.mod`, so there is nothing
+The home page suggests somewhere to start rather than opening on a wall of
-to install globally; `make setup` fetches it with the rest of the tooling.
+everything:
 
-On Linux, install the system libraries Wails needs. v3 builds against GTK4 +
+![The home page's shelves](docs/images/home.png)
-WebKitGTK 6.0 by default:
 
-```bash
+## Contributing, and the rest of the documentation
-sudo apt-get install libasound2-dev libgtk-4-dev libwebkitgtk-6.0-dev   # Debian/Ubuntu
-sudo pacman -S alsa-lib gtk4 webkitgtk-6.0                              # Arch
-```
 
-A machine without `webkitgtk-6.0` can still build with `-tags gtk3` against the
+- [`CONTRIBUTING.md`](CONTRIBUTING.md) — build it from source, run the tests,
-older WebKit2GTK 4.1 stack, but that is an escape hatch, not what CI or a
+  and how a change gets in.
-release builds.
+- [`CLAUDE.md`](CLAUDE.md) — the deep reference: the architecture and the reasons
-
+  behind the shape of it.
-macOS and Windows need no extra system packages. Run `go tool wails3 doctor` to
+- [The issue tracker](https://git.ljones.me/yonlu/yellowjacket/issues) is what
-check your environment.
+  is wanted and what is being worked on; **#73** is the roadmap.
-
+- [Releases](https://git.ljones.me/yonlu/yellowjacket/releases) double as the
-**Build**
+  changelog — every one is generated from the commits it contains.
-
-```bash
-make setup        # install tooling and git hooks
-make dev          # run with hot-reload
-make build-prod   # produce a release binary
-```
-
-More detail for contributors lives in [`CLAUDE.md`](./CLAUDE.md) — the
-architecture, the conventions and the reasons behind them. What is
-being worked on is [the issue
-tracker](https://git.ljones.me/yonlu/yellowjacket/issues); #73 is the
-roadmap.

backend/metadata/tags.go

@@ -74,6 +74,14 @@ func ExtractTags(path string) (*TrackMetadata, error) {
 
 // ExtractTagsFromReader reads metadata from an io.ReadSeeker.
 func ExtractTagsFromReader(r io.ReadSeeker) (*TrackMetadata, error) {
+	// The container decides, so this is asked before tag.ReadFrom and
+	// not after its failure: a WAV's tags live in a RIFF chunk that
+	// dhowden/tag cannot see, and its fallback -- an ID3v1 trailer --
+	// would otherwise outrank them.
+	if meta, ok := wavTags(r); ok {
+		return meta, nil
+	}
+
 	m, err := tag.ReadFrom(r)
 	if err != nil {
 		// No tags found is not necessarily an error - return empty metadata

backend/metadata/tags_wav.go

@@ -0,0 +1,68 @@
+package metadata
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+
+	"yellowjacket/backend/riff"
+)
+
+// wavTags reads the ID3v2 tag a WAV carries in its RIFF "id3 " chunk,
+// which is where backend/tagwriter puts it and where dhowden/tag --
+// having no RIFF reader at all -- cannot look.  Without this a WAV
+// scans as an untagged file however carefully it was tagged.
+//
+// ok is false when r is not a RIFF/WAVE container, and the read
+// position is restored either way so the caller can carry on.
+func wavTags(r io.ReadSeeker) (*TrackMetadata, bool) {
+	start, err := r.Seek(0, io.SeekCurrent)
+	if err != nil {
+		return nil, false
+	}
+
+	id3Data, chunkErr := riff.ID3Chunk(r)
+
+	if _, err := r.Seek(start, io.SeekStart); err != nil {
+		return nil, false
+	}
+
+	switch {
+	case chunkErr == nil:
+		return wavTagsFrom(id3Data), true
+
+	// Not ours to read: let the ordinary dispatch have the file.
+	case errors.Is(chunkErr, riff.ErrNotRIFF), errors.Is(chunkErr, riff.ErrNotWAVE):
+		return nil, false
+
+	// A RIFF container we cannot get a tag out of -- no chunk, an RF64
+	// file, a truncated header.  That is a file with no readable tags,
+	// which is what the scanner's filename fallback is for.
+	default:
+		return &TrackMetadata{}, true
+	}
+}
+
+// wavTagsFrom parses the bytes of a WAV's ID3v2 chunk.
+func wavTagsFrom(id3Data []byte) *TrackMetadata {
+	meta, err := extractID3v2Lenient(bytes.NewReader(id3Data))
+	if err != nil {
+		// A tag holding no frames is not a damaged tag: writing every
+		// field back out empty leaves one, and warning about it would
+		// put a fault on a file that has none.
+		if errors.Is(err, ErrTagsUnreadable) {
+			return &TrackMetadata{}
+		}
+
+		return &TrackMetadata{
+			TagReadWarning: fmt.Errorf("%w: %w", ErrTagsUnreadable, err),
+		}
+	}
+
+	// extractID3v2Lenient names MP3, being the recovery path for one.
+	meta.FileFormat = strings.ToUpper(strings.TrimPrefix(string(WAV), "."))
+
+	return meta
+}

backend/riff/riff.go

@@ -0,0 +1,186 @@
+// Package riff reads the chunk layout of a RIFF/WAVE container.
+//
+// It exists because both halves of WAV tagging need it and neither can
+// import the other: backend/tagwriter writes a WAV's tags into a RIFF
+// "id3 " chunk and already imports backend/metadata, which is what has
+// to read them back out.  backend/tagtotals is the precedent.
+//
+// The two readers here are deliberately different.  Parse holds every
+// chunk's data in memory, which is what rewriting a file needs; a WAV's
+// audio *is* the "data" chunk, so doing that on the scan path would
+// read every library file in full.  ID3Chunk seeks over what it is not
+// looking for instead.  Both walk the same headers.
+package riff
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+)
+
+// Sentinel errors describing a container this package will not read.
+var (
+	ErrRF64NotSupported = errors.New("RF64 files are not yet supported")
+	ErrNotRIFF          = errors.New("not a RIFF file")
+	ErrNotWAVE          = errors.New("not a WAVE file")
+	ErrNoID3Chunk       = errors.New("no ID3 chunk in RIFF file")
+)
+
+// Chunk holds a single RIFF sub-chunk (ID + raw data).
+type Chunk struct {
+	ID   [4]byte
+	Data []byte
+}
+
+// IsID3 reports whether id is that of an ID3v2 RIFF chunk.  Both
+// lowercase "id3 " and uppercase "ID3 " are accepted.
+func IsID3(id [4]byte) bool {
+	return strings.ToLower(string(id[:3])) == "id3"
+}
+
+// Parse reads every RIFF sub-chunk from r, in order, starting at the
+// reader's current position.  It rejects RF64 files and non-WAVE
+// containers with descriptive errors.  The parser is lenient: it
+// tolerates a missing final padding byte and ignores the declared
+// RIFF size.
+func Parse(r io.Reader) ([]Chunk, error) {
+	if err := readContainer(r); err != nil {
+		return nil, err
+	}
+
+	var chunks []Chunk
+
+	for {
+		id, size, err := nextHeader(r)
+		if errors.Is(err, io.EOF) {
+			break
+		}
+
+		if err != nil {
+			return nil, err
+		}
+
+		// Copied rather than allocated up front, as ID3Chunk does: the
+		// size is four bytes off the file, so a truncated one is free to
+		// declare a chunk larger than the whole of itself.
+		var data bytes.Buffer
+		if _, err := io.CopyN(&data, r, int64(size)); err != nil {
+			return nil, fmt.Errorf("read chunk data for %q: %w", id, err)
+		}
+
+		chunks = append(chunks, Chunk{ID: id, Data: data.Bytes()})
+
+		// Odd-length chunks have a padding byte.  Lenient: if the
+		// read fails (e.g. EOF), just break rather than error.
+		if size%2 != 0 {
+			var pad [1]byte
+
+			if _, err := r.Read(pad[:]); err != nil {
+				break
+			}
+		}
+	}
+
+	return chunks, nil
+}
+
+// ID3Chunk returns the payload of the ID3v2 chunk of the RIFF/WAVE
+// container at the reader's current position, seeking over every other
+// chunk rather than reading it.  It returns ErrNoID3Chunk when the
+// container carries no such chunk, and leaves the read position
+// unspecified either way.
+func ID3Chunk(r io.ReadSeeker) ([]byte, error) {
+	if err := readContainer(r); err != nil {
+		return nil, err
+	}
+
+	for {
+		id, size, err := nextHeader(r)
+		if errors.Is(err, io.EOF) {
+			return nil, ErrNoID3Chunk
+		}
+
+		if err != nil {
+			return nil, err
+		}
+
+		if !IsID3(id) {
+			// Odd-length chunks carry a padding byte.  Seeking past
+			// the end of the file is not an error; the next header
+			// read is what reports the end.
+			if _, err := r.Seek(int64(size)+int64(size%2), io.SeekCurrent); err != nil {
+				return nil, fmt.Errorf("skip chunk %q: %w", id, err)
+			}
+
+			continue
+		}
+
+		// Copied rather than allocated up front: a truncated file is
+		// free to declare a chunk larger than the whole of itself.
+		var data bytes.Buffer
+		if _, err := io.CopyN(&data, r, int64(size)); err != nil {
+			return nil, fmt.Errorf("read chunk data for %q: %w", id, err)
+		}
+
+		return data.Bytes(), nil
+	}
+}
+
+// readContainer consumes the 12-byte RIFF/WAVE header at the reader's
+// current position.
+func readContainer(r io.Reader) error {
+	var magic [4]byte
+	if _, err := io.ReadFull(r, magic[:]); err != nil {
+		return fmt.Errorf("read RIFF magic: %w", err)
+	}
+
+	if string(magic[:]) == "RF64" {
+		return ErrRF64NotSupported
+	}
+
+	if string(magic[:]) != "RIFF" {
+		return fmt.Errorf("%w: got %q", ErrNotRIFF, magic)
+	}
+
+	// Read (and discard) RIFF size — lenient, do not enforce.
+	var riffSize uint32
+	if err := binary.Read(r, binary.LittleEndian, &riffSize); err != nil {
+		return fmt.Errorf("read RIFF size: %w", err)
+	}
+
+	var form [4]byte
+	if _, err := io.ReadFull(r, form[:]); err != nil {
+		return fmt.Errorf("read WAVE form type: %w", err)
+	}
+
+	if string(form[:]) != "WAVE" {
+		return fmt.Errorf("%w: got %q", ErrNotWAVE, form)
+	}
+
+	return nil
+}
+
+// nextHeader reads one sub-chunk header.  It returns io.EOF once the
+// chunks are exhausted, including for a header cut short.
+func nextHeader(r io.Reader) ([4]byte, uint32, error) {
+	var id [4]byte
+
+	_, err := io.ReadFull(r, id[:])
+	if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
+		return id, 0, io.EOF
+	}
+
+	if err != nil {
+		return id, 0, fmt.Errorf("read chunk ID: %w", err)
+	}
+
+	var size uint32
+	if err := binary.Read(r, binary.LittleEndian, &size); err != nil {
+		return id, 0, fmt.Errorf("read chunk size for %q: %w", id, err)
+	}
+
+	return id, size, nil
+}

backend/riff/riff_test.go

@@ -0,0 +1,254 @@
+package riff_test
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"runtime"
+	"testing"
+
+	"yellowjacket/backend/riff"
+)
+
+// chunk is one sub-chunk to put in a test container.
+type chunk struct {
+	id   string
+	data []byte
+}
+
+// buildRIFF assembles a container from magic, form type and chunks,
+// padding odd-length chunks the way a writer must.
+func buildRIFF(magic, form string, chunks []chunk) []byte {
+	var body bytes.Buffer
+
+	body.WriteString(form)
+
+	for _, c := range chunks {
+		body.WriteString(c.id)
+		_ = binary.Write(&body, binary.LittleEndian, uint32(len(c.data)))
+		body.Write(c.data)
+
+		if len(c.data)%2 != 0 {
+			body.WriteByte(0)
+		}
+	}
+
+	var out bytes.Buffer
+
+	out.WriteString(magic)
+	_ = binary.Write(&out, binary.LittleEndian, uint32(body.Len()))
+	out.Write(body.Bytes())
+
+	return out.Bytes()
+}
+
+func TestID3Chunk_FindsTheTagPastTheAudio(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name   string
+		chunks []chunk
+		want   string
+	}{
+		{
+			name: "after an odd-length chunk",
+			chunks: []chunk{
+				{id: "fmt ", data: make([]byte, 16)},
+				{id: "LIST", data: []byte("INFOodd")},
+				{id: "data", data: make([]byte, 200)},
+				{id: "id3 ", data: []byte("ID3vTAG")},
+			},
+			want: "ID3vTAG",
+		},
+		{
+			// The chunk ID is written both ways in the wild, and the
+			// writer accepts either, so the reader must too.
+			name: "uppercase ID3",
+			chunks: []chunk{
+				{id: "data", data: make([]byte, 8)},
+				{id: "ID3 ", data: []byte("upper")},
+			},
+			want: "upper",
+		},
+		{
+			name: "first chunk",
+			chunks: []chunk{
+				{id: "id3 ", data: []byte("first")},
+				{id: "data", data: make([]byte, 8)},
+			},
+			want: "first",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			r := bytes.NewReader(buildRIFF("RIFF", "WAVE", tc.chunks))
+
+			got, err := riff.ID3Chunk(r)
+			if err != nil {
+				t.Fatalf("ID3Chunk: %v", err)
+			}
+
+			if string(got) != tc.want {
+				t.Errorf("chunk data: got %q, want %q", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestID3Chunk_RejectsWhatItCannotRead(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name  string
+		bytes []byte
+		want  error
+	}{
+		{
+			name:  "no ID3 chunk",
+			bytes: buildRIFF("RIFF", "WAVE", []chunk{{id: "data", data: []byte{1, 2}}}),
+			want:  riff.ErrNoID3Chunk,
+		},
+		{
+			name:  "no chunks at all",
+			bytes: buildRIFF("RIFF", "WAVE", nil),
+			want:  riff.ErrNoID3Chunk,
+		},
+		{
+			name:  "not RIFF",
+			bytes: []byte("ID3\x03\x00\x00\x00\x00\x00\x00\x00\x00"),
+			want:  riff.ErrNotRIFF,
+		},
+		{
+			name:  "not WAVE",
+			bytes: buildRIFF("RIFF", "AVI ", []chunk{{id: "id3 ", data: []byte("x")}}),
+			want:  riff.ErrNotWAVE,
+		},
+		{
+			name:  "RF64",
+			bytes: buildRIFF("RF64", "WAVE", []chunk{{id: "id3 ", data: []byte("x")}}),
+			want:  riff.ErrRF64NotSupported,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := riff.ID3Chunk(bytes.NewReader(tc.bytes))
+			if !errors.Is(err, tc.want) {
+				t.Errorf("ID3Chunk error: got %v, want %v", err, tc.want)
+			}
+		})
+	}
+}
+
+// A file cut short mid-chunk is a file with no tag, not a reason to
+// allocate the size it claims: the declared size is four bytes any
+// truncation can leave saying 4 GB.
+func TestID3Chunk_ToleratesATruncatedFile(t *testing.T) {
+	t.Parallel()
+
+	full := buildRIFF("RIFF", "WAVE", []chunk{
+		{id: "data", data: make([]byte, 64)},
+		{id: "id3 ", data: []byte("tag")},
+	})
+
+	t.Run("cut inside the audio", func(t *testing.T) {
+		t.Parallel()
+
+		_, err := riff.ID3Chunk(bytes.NewReader(full[:32]))
+		if !errors.Is(err, riff.ErrNoID3Chunk) {
+			t.Errorf("ID3Chunk error: got %v, want %v", err, riff.ErrNoID3Chunk)
+		}
+	})
+
+	t.Run("cut inside the tag", func(t *testing.T) {
+		t.Parallel()
+
+		if _, err := riff.ID3Chunk(bytes.NewReader(full[:len(full)-2])); err == nil {
+			t.Error("ID3Chunk: got nil error for a truncated tag chunk")
+		}
+	})
+}
+
+// Parse is the writer's half and reads every chunk into memory, which
+// is what preserving them needs.
+func TestParse_ReadsEveryChunkInOrder(t *testing.T) {
+	t.Parallel()
+
+	raw := buildRIFF("RIFF", "WAVE", []chunk{
+		{id: "fmt ", data: make([]byte, 16)},
+		{id: "LIST", data: []byte("INFOodd")},
+		{id: "id3 ", data: []byte("tag")},
+	})
+
+	chunks, err := riff.Parse(bytes.NewReader(raw))
+	if err != nil {
+		t.Fatalf("Parse: %v", err)
+	}
+
+	want := []string{"fmt ", "LIST", "id3 "}
+	if len(chunks) != len(want) {
+		t.Fatalf("chunk count: got %d, want %d", len(chunks), len(want))
+	}
+
+	for i, id := range want {
+		if got := string(chunks[i].ID[:]); got != id {
+			t.Errorf("chunk %d: got %q, want %q", i, got, id)
+		}
+	}
+
+	if !riff.IsID3(chunks[2].ID) || string(chunks[2].Data) != "tag" {
+		t.Errorf("id3 chunk: got %q", chunks[2].Data)
+	}
+
+	// The padding byte after an odd chunk is not part of its data.
+	if string(chunks[1].Data) != "INFOodd" {
+		t.Errorf("odd chunk data: got %q, want %q", chunks[1].Data, "INFOodd")
+	}
+}
+
+// A chunk size is four bytes read off the file, so a truncated or
+// malformed WAV is free to declare a chunk larger than the whole of
+// itself.  Parse must grow with what arrives rather than with what was
+// claimed.
+//
+// This measures the allocation instead of the error because the error
+// is the same either way: a build sizing its buffer from the header
+// reports the truncation correctly, having asked the allocator for a
+// gigabyte on the way.  Deliberately not parallel — TotalAlloc is
+// process-wide, and a test paused beside another one is measuring it
+// too.
+func TestParse_DoesNotAllocateWhatAChunkClaims(t *testing.T) {
+	// Large enough that a header-sized buffer is unmistakable, in a
+	// container of a few dozen bytes.
+	const declared = 1 << 30
+
+	var raw bytes.Buffer
+
+	raw.WriteString("RIFF")
+	_ = binary.Write(&raw, binary.LittleEndian, uint32(declared+12))
+	raw.WriteString("WAVE")
+	raw.WriteString("data")
+	_ = binary.Write(&raw, binary.LittleEndian, uint32(declared))
+	raw.WriteString("and then the file ends")
+
+	var before, after runtime.MemStats
+
+	runtime.GC()
+	runtime.ReadMemStats(&before)
+
+	if _, err := riff.Parse(bytes.NewReader(raw.Bytes())); err == nil {
+		t.Fatal("Parse: got nil error for a chunk larger than the file holding it")
+	}
+
+	runtime.ReadMemStats(&after)
+
+	if grew := after.TotalAlloc - before.TotalAlloc; grew > 1<<20 {
+		t.Errorf("Parse allocated %d bytes reading a %d-byte file whose chunk header claimed %d",
+			grew, raw.Len(), declared)
+	}
+}

backend/tagwriter/totals_test.go

@@ -13,9 +13,10 @@ import (
 // indistinguishable from never having written one.  So these assert the
 // round trip through the *reader the scan uses*, not the bytes.
 //
-// WAV is the exception and it is not this change's: dhowden/tag has no
+// WAV was the exception until #104 -- dhowden/tag has no RIFF reader,
-// RIFF reader at all, so metadata.ExtractTags cannot see a WAV's ID3
+// so metadata.ExtractTags could not see a WAV's ID3 chunk and this
-// chunk -- which is why every other test here reads that chunk itself.
+// case read the chunk itself, which is a test of the writer wearing
+// the shape of a round trip.  All four go through the scanner now.
 func TestWriteTotals_RoundTripsInEveryFormat(t *testing.T) {
 	t.Parallel()
 
@@ -91,7 +92,7 @@ func TestWriteTotals_RoundTripsInEveryFormat(t *testing.T) {
 		},
 		{
 			name: "wav",
-			read: readWavID3Tags,
+			read: viaScanner,
 			write: func(t *testing.T, dir string) string {
 				t.Helper()
 

backend/tagwriter/wav.go

@@ -8,116 +8,22 @@ import (
 	"io"
 	"log/slog"
 	"os"
-	"strings"
 
 	id3v2 "github.com/bogem/id3v2/v2"
 
 	"yellowjacket/backend/fileutil"
+	"yellowjacket/backend/riff"
 )
 
-// Sentinel errors for WAV RIFF operations.
+// errFileTooLargeForWAV is the one RIFF error that belongs to the
-var (
+// writer; reading rejects a container in backend/riff.
-	errRF64NotSupported   = errors.New("RF64 files are not yet supported")
+var errFileTooLargeForWAV = errors.New("file too large for WAV format (>4GB)")
-	errNotRIFF            = errors.New("not a RIFF file")
-	errNotWAVE            = errors.New("not a WAVE file")
-	errFileTooLargeForWAV = errors.New("file too large for WAV format (>4GB)")
-)
-
-// riffChunk holds a single RIFF sub-chunk (ID + raw data).
-type riffChunk struct {
-	id   [4]byte
-	data []byte
-}
-
-// parseRIFF reads all RIFF sub-chunks from r.  It rejects RF64 files
-// and non-WAVE containers with descriptive errors.  The parser is
-// lenient on read: it tolerates missing padding bytes and ignores
-// the declared RIFF size.
-func parseRIFF(r io.ReadSeeker) ([]riffChunk, error) {
-	// Read 4-byte container magic.
-	var magic [4]byte
-	if _, err := io.ReadFull(r, magic[:]); err != nil {
-		return nil, fmt.Errorf("read RIFF magic: %w", err)
-	}
-
-	if string(magic[:]) == "RF64" {
-		return nil, errRF64NotSupported
-	}
-
-	if string(magic[:]) != "RIFF" {
-		return nil, fmt.Errorf("%w: got %q", errNotRIFF, magic)
-	}
-
-	// Read (and discard) RIFF size — lenient, do not enforce.
-	var riffSize uint32
-	if err := binary.Read(r, binary.LittleEndian, &riffSize); err != nil {
-		return nil, fmt.Errorf("read RIFF size: %w", err)
-	}
-
-	// Read 4-byte form type.
-	var form [4]byte
-	if _, err := io.ReadFull(r, form[:]); err != nil {
-		return nil, fmt.Errorf("read WAVE form type: %w", err)
-	}
-
-	if string(form[:]) != "WAVE" {
-		return nil, fmt.Errorf("%w: got %q", errNotWAVE, form)
-	}
-
-	// Read sub-chunks until EOF.
-	var chunks []riffChunk
-
-	for {
-		var chunkID [4]byte
-
-		_, err := io.ReadFull(r, chunkID[:])
-		if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
-			break
-		}
-
-		if err != nil {
-			return nil, fmt.Errorf("read chunk ID: %w", err)
-		}
-
-		var chunkSize uint32
-		if err := binary.Read(r, binary.LittleEndian, &chunkSize); err != nil {
-			return nil, fmt.Errorf("read chunk size for %q: %w", chunkID, err)
-		}
-
-		data := make([]byte, chunkSize)
-		if _, err := io.ReadFull(r, data); err != nil {
-			return nil, fmt.Errorf("read chunk data for %q: %w", chunkID, err)
-		}
-
-		chunks = append(chunks, riffChunk{id: chunkID, data: data})
-
-		// Odd-length chunks have a padding byte.  Lenient: if the
-		// read fails (e.g. EOF), just break rather than error.
-		if chunkSize%2 != 0 {
-			var pad [1]byte
-
-			if _, err := r.Read(pad[:]); err != nil {
-				break
-			}
-		}
-	}
-
-	return chunks, nil
-}
-
-// isID3ChunkID returns true if id represents an ID3v2 RIFF chunk.
-// Both lowercase "id3 " and uppercase "ID3 " are accepted.
-func isID3ChunkID(id [4]byte) bool {
-	s := strings.ToLower(string(id[:3]))
-
-	return s == "id3"
-}
 
 // writeRIFF writes a complete RIFF/WAVE container to w, preserving
 // the given chunks in order and appending the id3Data as the final
 // "id3 " chunk.  Returns errFileTooLargeForWAV if the result would
 // exceed the 4 GB RIFF limit.
-func writeRIFF(w io.Writer, chunks []riffChunk, id3Data []byte) error {
+func writeRIFF(w io.Writer, chunks []riff.Chunk, id3Data []byte) error {
 	// Calculate total RIFF payload size:
 	//   4 bytes (WAVE form type)
 	// + for each preserved chunk: 8 (header) + len(data) + padding
@@ -125,7 +31,7 @@ func writeRIFF(w io.Writer, chunks []riffChunk, id3Data []byte) error {
 	riffPayload := uint64(4)
 
 	for _, c := range chunks {
-		sz := uint64(len(c.data))
+		sz := uint64(len(c.Data))
 		riffPayload += 8 + sz
 
 		if sz%2 != 0 {
@@ -162,7 +68,7 @@ func writeRIFF(w io.Writer, chunks []riffChunk, id3Data []byte) error {
 
 	// Write each preserved chunk.
 	for _, c := range chunks {
-		if err := writeChunk(w, c.id, c.data); err != nil {
+		if err := writeChunk(w, c.ID, c.Data); err != nil {
 			return err
 		}
 	}
@@ -225,7 +131,7 @@ func writeWavTags(
 		return fmt.Errorf("open wav for reading: %w", err)
 	}
 
-	allChunks, err := parseRIFF(f)
+	allChunks, err := riff.Parse(f)
 
 	// Close immediately — we need the handle released before
 	// AtomicWrite creates the replacement file.
@@ -237,13 +143,13 @@ func writeWavTags(
 
 	// Separate preserved chunks from existing ID3 data.
 	var (
-		preserved   []riffChunk
+		preserved   []riff.Chunk
 		existingID3 []byte
 	)
 
 	for _, c := range allChunks {
-		if isID3ChunkID(c.id) {
+		if riff.IsID3(c.ID) {
-			existingID3 = c.data
+			existingID3 = c.Data
 		} else {
 			preserved = append(preserved, c)
 		}

backend/tagwriter/wav_test.go

@@ -12,6 +12,7 @@ import (
 	id3v2 "github.com/bogem/id3v2/v2"
 
 	"yellowjacket/backend/metadata"
+	"yellowjacket/backend/riff"
 )
 
 // createTestWAV builds a minimal valid WAV file with an optional
@@ -270,6 +271,88 @@ func TestWriteWavTags_PartialUpdate(t *testing.T) {
 	assertStrField(t, "Composer", meta.Composer, "Original Composer")
 }
 
+// The writer has always been correct and the reader could not see it:
+// a WAV tagged by this app scanned as an untagged file, so editing
+// tags, autotagging a folder or importing a WAV download all appeared
+// to work and changed nothing the library could show (#104).  So this
+// asserts the write through metadata.ExtractTags -- the reader the
+// scan uses -- rather than through the id3 chunk.
+func TestWriteWavTags_ReadBackByTheScanner(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	path := createTestWAV(t, dir, "scanner.wav", nil)
+	art := tinyJPEG(t)
+
+	changes := TagChanges{
+		FieldTitle:       "Some Song",
+		FieldArtist:      "Some Artist",
+		FieldAlbum:       "Some Album",
+		FieldAlbumArtist: "Some Album Artist",
+		FieldGenre:       "Rock",
+		FieldYear:        2024,
+		FieldTrackNumber: 3,
+		FieldComposer:    "Some Composer",
+		FieldCoverArt:    art,
+	}
+
+	if err := writeWavTags(testLogger(), path, changes); err != nil {
+		t.Fatalf("writeWavTags: %v", err)
+	}
+
+	meta, err := metadata.ExtractTags(path)
+	if err != nil {
+		t.Fatalf("ExtractTags: %v", err)
+	}
+
+	if meta.TagReadWarning != nil {
+		t.Errorf("TagReadWarning: %v", meta.TagReadWarning)
+	}
+
+	assertStrField(t, "Title", meta.Title, "Some Song")
+	assertStrField(t, "Artist", meta.Artist, "Some Artist")
+	assertStrField(t, "Album", meta.Album, "Some Album")
+	assertStrField(t, "AlbumArtist", meta.AlbumArtist, "Some Album Artist")
+	assertStrField(t, "Genre", meta.Genre, "Rock")
+	assertStrField(t, "Composer", meta.Composer, "Some Composer")
+	assertStrField(t, "FileFormat", meta.FileFormat, "WAV")
+	assertIntField(t, "Year", meta.Year, 2024)
+	assertIntField(t, "TrackNumber", meta.TrackNumber, 3)
+
+	if !strings.HasPrefix(meta.TagFormat, "ID3v2") {
+		t.Errorf("TagFormat: got %q, want an ID3v2 version", meta.TagFormat)
+	}
+
+	if meta.Picture == nil {
+		t.Fatal("expected cover art, got nil")
+	}
+
+	if !bytes.Equal(meta.Picture.Data, art) {
+		t.Errorf("picture data mismatch: got %d bytes, want %d",
+			len(meta.Picture.Data), len(art))
+	}
+}
+
+// An untagged WAV is a file with no tags, not a file with a problem:
+// the scanner falls back to the filename and must not be handed a
+// warning to surface about it.
+func TestUntaggedWav_ReadsAsEmptyWithoutAWarning(t *testing.T) {
+	t.Parallel()
+
+	path := createTestWAV(t, t.TempDir(), "bare.wav", nil)
+
+	meta, err := metadata.ExtractTags(path)
+	if err != nil {
+		t.Fatalf("ExtractTags: %v", err)
+	}
+
+	if meta.TagReadWarning != nil {
+		t.Errorf("TagReadWarning: %v", meta.TagReadWarning)
+	}
+
+	assertStrField(t, "Title", meta.Title, "")
+}
+
 func TestWriteWavTags_ChunkPreservation(t *testing.T) {
 	t.Parallel()
 
@@ -282,7 +365,7 @@ func TestWriteWavTags_ChunkPreservation(t *testing.T) {
 		t.Fatalf("open original: %v", err)
 	}
 
-	origChunks, err := parseRIFF(origFile)
+	origChunks, err := riff.Parse(origFile)
 	_ = origFile.Close()
 
 	if err != nil {
@@ -292,7 +375,7 @@ func TestWriteWavTags_ChunkPreservation(t *testing.T) {
 	// Record original chunk data by ID string.
 	origData := map[string][]byte{}
 	for _, c := range origChunks {
-		origData[string(c.id[:])] = c.data
+		origData[string(c.ID[:])] = c.Data
 	}
 
 	// Write a tag to trigger RIFF rewrite.
@@ -309,7 +392,7 @@ func TestWriteWavTags_ChunkPreservation(t *testing.T) {
 		t.Fatalf("open after write: %v", err)
 	}
 
-	newChunks, err := parseRIFF(newFile)
+	newChunks, err := riff.Parse(newFile)
 	_ = newFile.Close()
 
 	if err != nil {
@@ -320,7 +403,7 @@ func TestWriteWavTags_ChunkPreservation(t *testing.T) {
 	origNonID3 := 0
 
 	for _, c := range origChunks {
-		if !isID3ChunkID(c.id) {
+		if !riff.IsID3(c.ID) {
 			origNonID3++
 		}
 	}
@@ -328,7 +411,7 @@ func TestWriteWavTags_ChunkPreservation(t *testing.T) {
 	newNonID3 := 0
 
 	for _, c := range newChunks {
-		if !isID3ChunkID(c.id) {
+		if !riff.IsID3(c.ID) {
 			newNonID3++
 		}
 	}
@@ -359,17 +442,17 @@ func TestWriteWavTags_ChunkPreservation(t *testing.T) {
 // in chunks and its data matches want byte-for-byte.
 func checkChunkPreserved(
 	t *testing.T,
-	chunks []riffChunk,
+	chunks []riff.Chunk,
 	idStr string,
 	want []byte,
 ) {
 	t.Helper()
 
 	for _, c := range chunks {
-		if string(c.id[:]) == idStr {
+		if string(c.ID[:]) == idStr {
-			if !bytes.Equal(c.data, want) {
+			if !bytes.Equal(c.Data, want) {
 				t.Errorf("chunk %q data changed: got %d bytes, want %d",
-					idStr, len(c.data), len(want))
+					idStr, len(c.Data), len(want))
 			}
 
 			return
@@ -430,7 +513,7 @@ func TestWriteWavTags_RejectsRF64(t *testing.T) {
 	buf.WriteString("WAVE")
 
 	// Minimal ds64 chunk (required for RF64 but we just need
-	// enough bytes for parseRIFF to hit the RF64 rejection).
+	// enough bytes for riff.Parse to hit the RF64 rejection).
 	buf.WriteString("ds64")
 	_ = binary.Write(&buf, binary.LittleEndian, uint32(28)) //nolint:mnd
 	buf.Write(make([]byte, 28))                             //nolint:mnd
@@ -454,9 +537,12 @@ func TestWriteWavTags_RejectsRF64(t *testing.T) {
 
 // readWavID3Tags extracts ID3v2 metadata from a WAV file by parsing
 // the RIFF structure and reading the id3 chunk with bogem/id3v2.
-// dhowden/tag's ReadFrom does not support WAV files, and its
+//
-// ReadID3v2Tags fails on empty tags (after clearing all frames).
+// metadata.ExtractTags reads a WAV since #104 and is what the round
-// Using bogem/id3v2.ParseReader handles all cases correctly.
+// trips assert through.  This stays for the two cases that are about
+// the bytes rather than about the scan: a tag with every frame
+// cleared, which no reader reports as anything, and the chunk
+// preservation test, which is already parsing the container itself.
 func readWavID3Tags(
 	t *testing.T,
 	path string,
@@ -470,17 +556,17 @@ func readWavID3Tags(
 
 	defer func() { _ = f.Close() }()
 
-	chunks, err := parseRIFF(f)
+	chunks, err := riff.Parse(f)
 	if err != nil {
-		t.Fatalf("parseRIFF: %v", err)
+		t.Fatalf("riff.Parse: %v", err)
 	}
 
 	// Find the id3 chunk.
 	var id3Data []byte
 
 	for _, c := range chunks {
-		if isID3ChunkID(c.id) {
+		if riff.IsID3(c.ID) {
-			id3Data = c.data
+			id3Data = c.Data
 
 			break
 		}

e2e/specs/long-press.spec.ts

@@ -1,127 +0,0 @@
-import { test, expect } from '../support/fixtures.js';
-
-/**
- * Long-press is the touch route to a context menu (plan 016 B2 phase 3).
- *
- * The component tier proves the gesture in isolation, against markup it
- * built itself. What it cannot prove is the half that made this one
- * listener instead of six: that the synthetic event reaches the handler
- * a *real* component bound — `track-list` delegates its `contextmenu`
- * on the `lit-virtualizer` rather than binding one per row — and that
- * the real `wa-popup` menu opens from it, which is a path with its own
- * history of opening and then refusing to work (see
- * `menu-keyboard.spec.ts`).
- *
- * The pointer events are dispatched rather than performed: this project
- * runs Desktop Chrome and Desktop Safari, neither of which has touch,
- * and a device tier does not exist. So this is honest about what it
- * checks — the app's own listeners, on the app's own DOM, from the
- * events a touch would produce — and not about a real finger.
- */
-
-/** A common small phone, as in `phone-shell.spec.ts`. */
-const PHONE = { width: 390, height: 844 };
-
-/** Comfortably past the module's 500ms hold. */
-const HELD = 900;
-
-type Page = import('@playwright/test').Page;
-
-/** The track list's menu panel, or null while it is not rendered. */
-const panel = (page: Page) =>
-  page.evaluate(() => {
-    const el = document
-      .querySelector('track-list')
-      ?.shadowRoot?.querySelector('.context-menu-panel');
-
-    if (!el) return null;
-
-    return {
-      role: el.getAttribute('role'),
-      label: el.getAttribute('aria-label'),
-      items: el.querySelectorAll('[role="menuitem"]').length,
-    };
-  });
-
-/**
- * Press the first track row, optionally dragging partway through — the
- * shape of a scroll that begins on a row, which must not open a menu.
- */
-async function pressFirstRow(
-  page: Page,
-  opts: { driftY?: number } = {},
-): Promise<void> {
-  await page.evaluate((drift) => {
-    // `.track-row`, not `[role="row"]`: the column header is a row too,
-    // and it is the *first* one -- a press on it is correctly ignored,
-    // which reads exactly like the gesture not working.
-    const row = document
-      .querySelector('track-list')
-      ?.shadowRoot?.querySelector('.track-row');
-
-    if (!row) throw new Error('no track row to press');
-
-    const box = row.getBoundingClientRect();
-    const x = Math.round(box.left + box.width / 2);
-    const y = Math.round(box.top + box.height / 2);
-    const send = (type: string, dy = 0) =>
-      row.dispatchEvent(
-        new PointerEvent(type, {
-          bubbles: true,
-          composed: true,
-          cancelable: true,
-          pointerType: 'touch',
-          isPrimary: true,
-          clientX: x,
-          clientY: y + dy,
-        }),
-      );
-
-    send('pointerdown');
-
-    if (drift) send('pointermove', drift);
-  }, opts.driftY ?? 0);
-}
-
-test.describe('long-press opens the track menu', () => {
-  test.beforeEach(async ({ app }) => {
-    await app.setViewportSize(PHONE);
-    await app.getByTestId('tab-tracks').click();
-    await expect(app.getByTestId('main-content')).toHaveAttribute(
-      'data-active-view',
-      'tracks',
-    );
-  });
-
-  test.afterEach(async ({ app }) => {
-    // Every other spec file runs against a desktop, and the viewport
-    // belongs to the shared context rather than to this file.
-    await app.setViewportSize({ width: 1440, height: 900 });
-  });
-
-  test('reaches the delegated handler and opens the real menu', async ({
-    app,
-  }) => {
-    await expect.poll(() => panel(app)).toBeNull();
-
-    await pressFirstRow(app);
-
-    await expect
-      .poll(() => panel(app), { timeout: HELD + 2000 })
-      .toMatchObject({ role: 'menu', label: 'Track actions' });
-
-    // The same panel Shift+F10 opens, items and all -- not an empty
-    // popup that happened to become visible.
-    expect((await panel(app))?.items).toBeGreaterThan(0);
-  });
-
-  test('does not open one for a press that turns into a scroll', async ({
-    app,
-  }) => {
-    await pressFirstRow(app, { driftY: 40 });
-
-    await app.waitForTimeout(HELD);
-
-    expect(await panel(app)).toBeNull();
-  });
-});

e2e/specs/native-touch-feel.spec.ts

@@ -0,0 +1,140 @@
+import { test, expect } from '../support/fixtures.js';
+
+/**
+ * The web view's own tap highlight, and what replaced it (#54).
+ *
+ * Two halves, and each is here because no other tier can see it.
+ *
+ * **The highlight is killed by one declaration on `html`**, which
+ * reaches the app's shadow roots because `-webkit-tap-highlight-color`
+ * is inherited and inheritance crosses a shadow boundary. That is a
+ * property of `index.css`, and `index.css` is loaded by the real app
+ * and by nothing else — the component tier mounts a component with no
+ * page stylesheet at all, which is the same reason the theme's ramps
+ * are invisible to it.
+ *
+ * **The press state is measured rather than read.** The component tier
+ * asserts the shape of the stylesheet (which rule is inside which
+ * query, and that the press selector carries a state class), because
+ * `:active` cannot be forced there. Here there is a real pointer: hold
+ * the button down on a real row of the real list and read what the row
+ * became. That is the assertion that would fail if the rule were
+ * hoisted, renamed, or lost to `.selected`.
+ *
+ * What neither half is, is the device. Chrome 113's WebView is where
+ * the grey box was reported and where a finger is; the numbers from it
+ * are on the PR.
+ */
+type Page = import('@playwright/test').Page;
+
+/** The phone this work was measured against, in CSS pixels. */
+const DEVICE = { width: 424, height: 439 };
+
+/** The computed tap-highlight colour of a node inside a shadow root. */
+const tapHighlight = (page: Page, host: string, inner: string) =>
+  page.evaluate(
+    ([hostSel, innerSel]) => {
+      const el = document
+        .querySelector(hostSel!)
+        ?.shadowRoot?.querySelector(innerSel!);
+
+      if (!el) return null;
+
+      return getComputedStyle(el).getPropertyValue(
+        '-webkit-tap-highlight-color',
+      );
+    },
+    [host, inner],
+  );
+
+test.describe('the tap highlight', () => {
+  test('is transparent inside a shadow root, from one rule on html', async ({
+    app,
+    browserName,
+  }) => {
+    await app.getByTestId('nav-tracks').click();
+    await expect(app.getByTestId('main-content')).toHaveAttribute(
+      'data-active-view',
+      'tracks',
+    );
+
+    const row = await tapHighlight(app, 'track-list', '.track-row');
+
+    expect(row).not.toBeNull();
+
+    // The property is a WebKit extension that only iOS honours, so an
+    // engine is free not to report one at all. Chromium always does —
+    // measured at rgba(0, 0, 0, 0.18) with the rule removed, which is
+    // the grey box the report describes — so the assertion is not
+    // skippable there, and nothing this app can do makes the property
+    // disappear on an engine that has it.
+    test.skip(
+      row === '',
+      `${browserName} reports no -webkit-tap-highlight-color to read`,
+    );
+
+    expect(row).toBe('rgba(0, 0, 0, 0)');
+  });
+});
+
+test.describe('the press state that replaced it', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(DEVICE);
+    await app.getByTestId('tab-tracks').click();
+    await expect(app.getByTestId('main-content')).toHaveAttribute(
+      'data-active-view',
+      'tracks',
+    );
+    await expect(app.locator('track-list').first()).toBeVisible();
+  });
+
+  test.afterEach(async ({ app }) => {
+    await app.mouse.up();
+    await app.setViewportSize({ width: 1440, height: 900 });
+  });
+
+  test('shows on the row being pressed, and on that row only', async ({
+    app,
+  }) => {
+    const rows = await app.evaluate(() => {
+      const found = document
+        .querySelector('track-list')
+        ?.shadowRoot?.querySelectorAll('.track-row');
+
+      if (!found || found.length < 2) return null;
+
+      const rect = found[1]!.getBoundingClientRect();
+
+      return {
+        x: Math.round(rect.x + rect.width / 2),
+        y: Math.round(rect.y + rect.height / 2),
+      };
+    });
+
+    expect(rows).not.toBeNull();
+
+    const backgrounds = () =>
+      app.evaluate(() => {
+        const found = document
+          .querySelector('track-list')!
+          .shadowRoot!.querySelectorAll('.track-row');
+
+        return {
+          pressed: getComputedStyle(found[1]!).backgroundColor,
+          neighbour: getComputedStyle(found[2]!).backgroundColor,
+        };
+      });
+
+    await app.mouse.move(rows!.x, rows!.y);
+    await app.mouse.down();
+
+    const held = await backgrounds();
+
+    // The press overlay, from the theme rather than from a literal in
+    // a component: rgba(255, 255, 255, 0.12) on both dark ramps.
+    expect(held.pressed).toBe('rgba(255, 255, 255, 0.12)');
+    expect(held.neighbour).not.toBe(held.pressed);
+
+    await app.mouse.up();
+  });
+});

e2e/specs/phone-entity-links.spec.ts

@@ -0,0 +1,135 @@
+import {
+  test,
+  expect,
+  callBinding,
+  openTheQueue,
+  NO_QUEUE_SOURCE,
+} from '../support/fixtures.js';
+import type { Page } from '@playwright/test';
+
+/**
+ * #67 — a name is not a link on a phone, and the menu is where it went.
+ *
+ * The queue panel is the surface this is visible on: its rows draw a
+ * track title and an artist credit as `explore-link`s at every width,
+ * unlike `track-list`, whose phone column set stacks title over artist
+ * as plain text already.
+ *
+ * **The pair is what makes either assertion mean anything.** A link
+ * that is gone and a menu item that never arrived is not a smaller
+ * affordance — it is a destination the phone cannot reach, which is
+ * what plan 018's "no action is unreachable at any supported size"
+ * refuses. So each test asserts the phone and the desktop in the same
+ * breath: text *and* an item here, a link *and* no item there.
+ *
+ * The desktop half is also the regression guard for the change: menus
+ * above the breakpoint must be exactly what they were, because the name
+ * beside them is still a link and a menu that repeats the row is
+ * furniture.
+ */
+
+/** The reference device's real viewport, not a resized desktop. */
+const DEVICE = { width: 424, height: 439 };
+
+/** Wide enough that the queue is a column beside the content. */
+const DESKTOP = { width: 1280, height: 800 };
+
+const row = (app: Page, index: number) =>
+  app.locator(`queue-panel .track-item[data-index="${index}"]`);
+
+/** The queue panel's own context menu, as a list of item labels. */
+async function menuLabels(app: Page): Promise<string[]> {
+  return app.evaluate(() =>
+    [
+      ...document
+        .querySelector('queue-panel')!
+        .shadowRoot!.querySelectorAll('wa-dropdown-item'),
+    ].map((item) => item.textContent?.replace(/\s+/g, ' ').trim() ?? ''),
+  );
+}
+
+/**
+ * Queue three tracks that have an album, for the reason
+ * `queue-selection.spec.ts` states at length: `explore-link` routes a
+ * title to its *album's* page and renders plain text where it cannot
+ * route, so a track with no album answers this file's question with
+ * the wrong "no link".
+ */
+async function queueThree(app: Page): Promise<void> {
+  const paths = await app.evaluate(async () => {
+    const tracks = (await window.__yjEvents.call(
+      'library.Library.GetTracks',
+      [0],
+      10_000,
+    )) as { FilePath: string; Album: string; ArtistName: string }[];
+
+    return tracks
+      .filter((t) => t.Album !== '' && t.ArtistName !== '')
+      .slice(0, 3)
+      .map((t) => t.FilePath);
+  });
+
+  await callBinding(app, 'queue.Queue.SetQueue', [
+    paths,
+    0,
+    false,
+    NO_QUEUE_SOURCE,
+  ]);
+}
+
+/** Open the row's context menu and read the items back. */
+async function openRowMenu(app: Page, index: number): Promise<string[]> {
+  await row(app, index).click({ button: 'right' });
+  await expect
+    .poll(async () => (await menuLabels(app)).length)
+    .toBeGreaterThan(0);
+
+  return menuLabels(app);
+}
+
+test.describe('an inline name and the menu that replaces it', () => {
+  test.afterEach(async ({ app }) => {
+    await app.keyboard.press('Escape');
+    await callBinding(app, 'queue.Queue.Clear').catch(() => {
+      /* an empty queue is the state we were asking for */
+    });
+    await app.setViewportSize(DESKTOP);
+  });
+
+  test('a queue row is plain text on a phone and carries the destination', async ({
+    app,
+  }) => {
+    await app.setViewportSize(DEVICE);
+    await queueThree(app);
+    await openTheQueue(app);
+    await expect(row(app, 0)).toBeVisible();
+
+    // The name is text: nothing in the row is a link at all.
+    await expect(app.locator('queue-panel .track-item .explore-link')).toHaveCount(
+      0,
+    );
+
+    const labels = await openRowMenu(app, 0);
+
+    expect(labels).toContain('Go to Artist');
+    expect(labels).toContain('Go to Album');
+  });
+
+  test('the same row on a desktop is a link, and its menu is untouched', async ({
+    app,
+  }) => {
+    await app.setViewportSize(DESKTOP);
+    await queueThree(app);
+    await openTheQueue(app);
+    await expect(row(app, 0)).toBeVisible();
+
+    await expect(
+      row(app, 0).locator('.track-title .explore-link'),
+    ).toHaveCount(1);
+
+    const labels = await openRowMenu(app, 0);
+
+    expect(labels).not.toContain('Go to Artist');
+    expect(labels).not.toContain('Go to Album');
+  });
+});

e2e/specs/phone-shell.spec.ts

@@ -98,6 +98,58 @@ test.describe('the shell on a phone', () => {
     ).toBeVisible();
   });
 
+  test('draws "More" as a sheet on the bottom edge (#71)', async ({ app }) => {
+    await app.getByTestId('tab-more').click();
+    await expect(app.getByTestId('nav-drawer').locator('app-sidebar'))
+      .toBeVisible();
+
+    // What the report is about is geometry, and geometry is what no
+    // other assertion here can see: the side drawer was a 200px column
+    // opening away from the thumb that asked for it, with the rest of
+    // its 400px band empty. Measured rather than screenshotted, since
+    // the failure is a number.
+    //
+    // Polled, because a sheet *arrives*: the drawer's show animation
+    // translates it a full height below the fold, so a measurement
+    // taken the moment its content is visible reports a box hanging
+    // 412px off the bottom of the screen. Asking for the settled
+    // number is the assertion; asking once is a race.
+    const measure = () => app.evaluate(() => {
+      const nav = document.querySelector('bottom-nav');
+      const drawer = nav?.shadowRoot?.querySelector('wa-drawer');
+      const dialog = drawer?.shadowRoot?.querySelector('[part~="dialog"]');
+      const sidebar = nav?.shadowRoot?.querySelector('app-sidebar');
+      const row = sidebar?.shadowRoot?.querySelector('li button');
+      const box = dialog?.getBoundingClientRect();
+
+      return {
+        left: Math.round(box?.left ?? -1),
+        right: Math.round(box?.right ?? -1),
+        bottom: Math.round(box?.bottom ?? -1),
+        height: Math.round(box?.height ?? -1),
+        row: Math.round(row?.getBoundingClientRect().height ?? -1),
+        viewport: [window.innerWidth, window.innerHeight],
+      };
+    });
+
+    await expect
+      .poll(async () => (await measure()).bottom)
+      .toBe(PHONE.height);
+
+    const sheet = await measure();
+
+    expect(sheet.left).toBe(0);
+    expect(sheet.right).toBe(sheet.viewport[0]);
+
+    // A surface covering the whole screen is a page, not a sheet --
+    // which is also what leaves an outside to tap on, the only pointer
+    // route out of it (#171 is the same question one surface over).
+    expect(sheet.height).toBeLessThan(sheet.viewport[1]);
+
+    // 48px rows, from #186's touch floor and #60's context sheet.
+    expect(sheet.row).toBeGreaterThanOrEqual(48);
+  });
+
   for (const vp of [PHONE, SMALL_PHONE]) {
     test(`does not scroll sideways at ${vp.width}×${vp.height}`, async ({ app }) => {
       await app.setViewportSize(vp);

e2e/specs/queue-overlay.spec.ts

@@ -157,6 +157,62 @@ test.describe('an overlaid queue says it is over the content', () => {
   });
 });
 
+/**
+ * #170 — the other two buttons in that same row.
+ *
+ * Clear queue and Add queue to playlist predate the close button and
+ * were named by a `title` attribute and nothing else. Unlike the
+ * sliders in `control-names.spec.ts`, that is not a *missing* name:
+ * `title` is the last fallback in the accname order, so
+ * `getByRole('button', { name: 'Clear queue' })` matched them before
+ * this fix as well as after it — measured, 1 and 1. A sweep for empty
+ * names cannot see a weak one, which is `a11y.26`'s complaint and the
+ * reason this file could have grown a green test that proved nothing.
+ *
+ * So the name is asserted twice, and the second assertion is the one
+ * that fails on the broken build. Taking the tooltip away and asking
+ * again is the property in words: **the name is not the tooltip**. It
+ * is what makes the button survive content being put inside it later,
+ * and it is the only one of the two a phone has — there is no hover on
+ * the surface #55 turned into a full screen. Measured on `main` before
+ * the fix: 0 and 0.
+ *
+ * Both buttons are disabled here, because the queue starts empty and
+ * naming is not enablement. A disabled button is still in the
+ * accessibility tree, which is exactly where the complaint was.
+ */
+test.describe('the queue header says what its actions do', () => {
+  const ACTIONS = ['Clear queue', 'Add queue to playlist'];
+
+  test('names both of the older actions', async ({ app }) => {
+    await openQueue(app);
+
+    for (const name of ACTIONS) {
+      await expect(
+        app.getByRole('button', { name, exact: true }),
+      ).toHaveCount(1);
+    }
+  });
+
+  test('and the names do not come from the tooltip', async ({ app }) => {
+    await openQueue(app);
+
+    await app.locator('#queue-panel').evaluate((el) => {
+      for (const button of el.shadowRoot!.querySelectorAll(
+        '.header-action-button',
+      )) {
+        button.removeAttribute('title');
+      }
+    });
+
+    for (const name of ACTIONS) {
+      await expect(
+        app.getByRole('button', { name, exact: true }),
+      ).toHaveCount(1);
+    }
+  });
+});
+
 /**
  * The inline panel is the mode that already worked, and the one every
  * other queue spec is written against. It keeps its resize handle and

e2e/specs/queue-selection.spec.ts

@@ -103,12 +103,17 @@ async function queueSixAndOpen(app: Page): Promise<void> {
      *
      * `explore-link` routes a track name to its *album's* page, so a
      * track with no album renders a name that navigates nowhere — and
-     * the fixture library deliberately contains two (`01 Tone A`,
+     * the fixture library deliberately contains two,
-     * `02 Tone B`). Which tracks arrive first is `audio_files.id`
+     * `unsorted/no-tags-at-all.mp3` and `unsorted/title-only.mp3`.
-     * order, i.e. the order the **scan** inserted them, which depends
+     * (It contained four until #104: the two WAVs under `Field
-     * on concurrency and directory traversal: locally the first eight
+     * Recordings/Test Tones` had been tagged on disk all along and
-     * all had albums and the spec passed twice over, and CI rebuilds
+     * scan in with their album now, so they are ordinary tracks and
-     * its seed with a real scan and got a different eight.
+     * not examples of this.) Which tracks arrive first is
+     * `audio_files.id` order, i.e. the order the **scan** inserted
+     * them, which depends on concurrency and directory traversal:
+     * locally the first eight all had albums and the spec passed twice
+     * over, and CI rebuilds its seed with a real scan and got a
+     * different eight.
      *
      * Asking for what the test needs is the fix. It is not a
      * narrowing: every assertion here wants an ordinary track, and

e2e/specs/touch-gestures.spec.ts

@@ -0,0 +1,311 @@
+import { test, expect, callBinding } from '../support/fixtures.js';
+
+/**
+ * The touch gestures against the real app (plan 019, #63; long-press
+ * from plan 016 B2).
+ *
+ * The component tier proves the gestures in isolation, against markup
+ * it built itself. What it cannot prove is the half that made this one
+ * document listener instead of six: that the announced gesture reaches
+ * the handler a *real* component bound — `track-list` delegates on the
+ * `lit-virtualizer` rather than binding per row — and that the real
+ * menu opens from it, a path with its own history of opening and then
+ * refusing to work (see `menu-keyboard.spec.ts`).
+ *
+ * **Both halves of the reassignment are here, and the second is the
+ * one that matters.** #63 makes a hold on a *track row* mean selection
+ * mode; every other surface in the app keeps the context menu it has
+ * had, because an unclaimed `yj-long-press` still becomes a
+ * `contextmenu`. A spec that only checked the row would pass on a
+ * build that had silently broken the other thirteen menus.
+ *
+ * The pointer events are dispatched rather than performed: this
+ * project runs Desktop Chrome and Desktop Safari, neither of which has
+ * touch. So this is honest about what it checks — the app's own
+ * listeners, on the app's own DOM, from the events a touch would
+ * produce — and not about a real finger. The finger is the Android
+ * tier, and it found something this cannot see: Chrome 113's WebView
+ * fires its own `contextmenu` on a long press, which is why the module
+ * announces the gesture from a native event rather than standing down.
+ */
+
+/** A common small phone, as in `phone-shell.spec.ts`. */
+const PHONE = { width: 390, height: 844 };
+
+/** Comfortably past the module's 500ms hold. */
+const HELD = 900;
+
+type Page = import('@playwright/test').Page;
+
+/** A component's menu panel, or null while it is not rendered. */
+const panel = (page: Page, host: string) =>
+  page.evaluate((tag) => {
+    const el = document
+      .querySelector(tag)
+      ?.shadowRoot?.querySelector('.context-menu-panel');
+
+    if (!el) return null;
+
+    return {
+      role: el.getAttribute('role'),
+      label: el.getAttribute('aria-label'),
+      items: el.querySelectorAll('[role="menuitem"]').length,
+    };
+  }, host);
+
+/** How many tracks the selection bar says are selected, or null. */
+const selectionCount = (page: Page) =>
+  page.evaluate(() => {
+    const bar = document
+      .querySelector('track-list')
+      ?.shadowRoot?.querySelector('selection-bar');
+
+    return bar ? (bar as unknown as { count: number }).count : null;
+  });
+
+/**
+ * Press an element, optionally dragging partway through — the shape of
+ * a scroll that begins on a row, which must be neither gesture — and
+ * optionally lifting, which is what makes it a tap rather than a hold.
+ */
+async function press(
+  page: Page,
+  selector: { host: string; inner: string },
+  opts: { driftY?: number; lift?: boolean } = {},
+): Promise<void> {
+  await page.evaluate(
+    ({ host, inner, drift, lift }) => {
+      const el = document
+        .querySelector(host)
+        ?.shadowRoot?.querySelector(inner);
+
+      if (!el) throw new Error(`no ${inner} in ${host} to press`);
+
+      const box = el.getBoundingClientRect();
+      const x = Math.round(box.left + box.width / 2);
+      const y = Math.round(box.top + box.height / 2);
+      const send = (type: string, dy = 0) =>
+        el.dispatchEvent(
+          new PointerEvent(type, {
+            bubbles: true,
+            composed: true,
+            cancelable: true,
+            pointerType: 'touch',
+            isPrimary: true,
+            clientX: x,
+            clientY: y + dy,
+          }),
+        );
+
+      send('pointerdown');
+
+      if (drift) send('pointermove', drift);
+      if (lift) send('pointerup');
+    },
+    {
+      host: selector.host,
+      inner: selector.inner,
+      drift: opts.driftY ?? 0,
+      lift: opts.lift ?? false,
+    },
+  );
+}
+
+// `.track-row`, not `[role="row"]`: the column header is a row too, and
+// it is the *first* one — a press on it is correctly ignored, which
+// reads exactly like the gesture not working.
+const TRACK_ROW = { host: 'track-list', inner: '.track-row' };
+
+test.describe('a hold on a track row selects it', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(PHONE);
+    await app.getByTestId('tab-tracks').click();
+    await expect(app.getByTestId('main-content')).toHaveAttribute(
+      'data-active-view',
+      'tracks',
+    );
+  });
+
+  test.afterEach(async ({ app }) => {
+    // Every other spec file runs against a desktop, and the viewport
+    // belongs to the shared context rather than to this file.
+    await app.setViewportSize({ width: 1440, height: 900 });
+  });
+
+  test('raises the selection bar rather than the context menu', async ({
+    app,
+  }) => {
+    await expect.poll(() => selectionCount(app)).toBeNull();
+
+    await press(app, TRACK_ROW);
+
+    await expect
+      .poll(() => selectionCount(app), { timeout: HELD + 2000 })
+      .toBe(1);
+
+    // The gesture is claimed, so the menu this hold used to open must
+    // not also be up -- on a phone that would be a sheet over the bar.
+    expect(await panel(app, 'track-list')).toBeNull();
+  });
+
+  test('is neither gesture when the press turns into a scroll', async ({
+    app,
+  }) => {
+    await press(app, TRACK_ROW, { driftY: 40 });
+    await app.waitForTimeout(HELD);
+
+    expect(await selectionCount(app)).toBeNull();
+    expect(await panel(app, 'track-list')).toBeNull();
+  });
+});
+
+test.describe('a hold anywhere else still opens the menu', () => {
+  test.beforeEach(async ({ app }) => {
+    await app.setViewportSize(PHONE);
+    await app.getByTestId('tab-albums').click();
+    await expect(app.getByTestId('main-content')).toHaveAttribute(
+      'data-active-view',
+      'albums',
+    );
+  });
+
+  test.afterEach(async ({ app }) => {
+    await app.setViewportSize({ width: 1440, height: 900 });
+  });
+
+  test('reaches the delegated handler and opens the real menu', async ({
+    app,
+  }) => {
+    // The property that let #63 reassign the hold without touching one
+    // of the fourteen context menus: unclaimed, it is what it was.
+    // Without this half, breaking all of them passes the suite.
+    await expect.poll(() => panel(app, 'cover-grid')).toBeNull();
+
+    await press(app, { host: 'cover-grid', inner: '[role="option"]' });
+
+    await expect
+      .poll(() => panel(app, 'cover-grid'), { timeout: HELD + 2000 })
+      .toMatchObject({ role: 'menu' });
+
+    // The same panel Shift+F10 opens, items and all -- not an empty
+    // popup that happened to become visible.
+    expect((await panel(app, 'cover-grid'))?.items).toBeGreaterThan(0);
+  });
+});
+
+/**
+ * Swipe right on a track row to queue it (plan 019 phase 2, #63).
+ *
+ * The component tier has the rule this obeys — one row is a position,
+ * several are a choice — against a queue that is a fake. What is only
+ * true here is that the gesture reaches the *real* queue: `AddTracks`
+ * is a Go method, the queue is persisted, and "the row was added"
+ * is a question only the backend can answer.
+ *
+ * **It is Chromium-only, and that is a property of the browser rather
+ * than a gap.** The gesture runs on touch events, because Chrome 113's
+ * WebView cancels the pointer stream ~16px into any drag whatever
+ * `touch-action` says. Desktop WebKit implements no `TouchEvent`
+ * constructor at all — touch events are a mobile-Safari surface — so
+ * the events this needs cannot be built there. Skipping loudly is
+ * better than a spec that quietly asserts nothing on half the matrix,
+ * which is what `layout-overflow.spec.ts` and `back-navigation.spec.ts`
+ * were each doing when they were green on a broken build.
+ */
+test.describe('a swipe right on a track row queues it', () => {
+  test.beforeEach(async ({ app, browserName }) => {
+    test.skip(
+      browserName !== 'chromium',
+      'desktop WebKit has no TouchEvent constructor to build the gesture from',
+    );
+
+    await app.setViewportSize(PHONE);
+    await app.getByTestId('tab-tracks').click();
+    await expect(app.getByTestId('main-content')).toHaveAttribute(
+      'data-active-view',
+      'tracks',
+    );
+  });
+
+  test.afterEach(async ({ app }) => {
+    await app.setViewportSize({ width: 1440, height: 900 });
+  });
+
+  /**
+   * Drag the first row sideways by a fraction of its own width and
+   * lift. `fraction` is against the row, because the commit threshold
+   * is — a number of pixels here would be a second declaration of it,
+   * right on one viewport and wrong on the next.
+   */
+  const swipeFirstRow = (page: Page, fraction: number) =>
+    page.evaluate((f) => {
+      const row = document
+        .querySelector('track-list')
+        ?.shadowRoot?.querySelector('.track-row');
+
+      if (!row) throw new Error('no track row to swipe');
+
+      const box = row.getBoundingClientRect();
+      const y = box.top + box.height / 2;
+      const at = (x: number) =>
+        new Touch({
+          identifier: 1,
+          target: row,
+          clientX: box.left + x,
+          clientY: y,
+        });
+      const send = (type: string, points: Touch[]) =>
+        row.dispatchEvent(
+          new TouchEvent(type, {
+            bubbles: true,
+            composed: true,
+            cancelable: true,
+            touches: points,
+            changedTouches: points.length > 0 ? points : [at(0)],
+          }),
+        );
+
+      send('touchstart', [at(0)]);
+
+      for (const step of [0.25, 0.5, 0.75, 1]) {
+        send('touchmove', [at(box.width * f * step)]);
+      }
+
+      send('touchend', []);
+    }, fraction);
+
+  /** How many tracks the backend says are in the queue. */
+  const queueLength = async (page: Page) => {
+    const state = await callBinding<{ tracks: unknown[] }>(
+      page,
+      'queue.Queue.GetState',
+    );
+
+    return state.tracks?.length ?? 0;
+  };
+
+  test('adds exactly one track to the real queue', async ({ app }) => {
+    const before = await queueLength(app);
+
+    await swipeFirstRow(app, 0.6);
+
+    await expect.poll(() => queueLength(app)).toBe(before + 1);
+
+    // Queued, not played: a swipe is not a tap, and the difference is
+    // what is on screen afterwards.
+    expect(
+      await app.getByTestId('main-content').getAttribute('data-active-view'),
+    ).toBe('tracks');
+  });
+
+  test('does nothing when the finger did not get far enough', async ({
+    app,
+  }) => {
+    const before = await queueLength(app);
+
+    await swipeFirstRow(app, 0.1);
+    await app.waitForTimeout(400);
+
+    expect(await queueLength(app)).toBe(before);
+  });
+});

frontend/index.css

@@ -7,6 +7,26 @@
 
 html {
     height: 100%;
+
+    /* #54.  The web view's own tap highlight -- the grey box a phone
+       draws over the bounding rect of whatever was tapped -- gone in
+       one declaration, because `-webkit-tap-highlight-color` is an
+       *inherited* property and an inherited property crosses a shadow
+       boundary.  So this reaches every one of the app's shadow roots
+       without a rule in any of them; before it, exactly one component
+       (`library-status-indicator`) set it and the box appeared
+       everywhere else.
+
+       What it costs is the only touch feedback several surfaces had,
+       which is why the rows, the tab bar and the shared menu items
+       grew a `:active` state in the same change: removing the wrong
+       feedback and leaving none is not an improvement.  The cards
+       already had one (`transform: scale(0.97)`).
+
+       `user-select` is the same argument one rule up and was already
+       done: the `*` rule at the top of this file is inherited into the
+       shadow roots too. */
+    -webkit-tap-highlight-color: transparent;
 }
 
 body {

frontend/index.ts

@@ -70,7 +70,7 @@ import '@store/theme-store';
 // registers the document keydown listener for global shortcuts.
 import './src/services/keyboard-shortcut-service';
 import { activateView, deactivateView } from '@utils/view-lifecycle';
-import { installLongPressContextMenu } from '@utils/long-press';
+import { installTouchGestures } from '@utils/touch-gestures';
 import { openQueue, queuePanelElement } from '@utils/open-queue';
 import { installTopBarFit } from './src/services/top-bar-fit';
 import {
@@ -87,10 +87,13 @@ setBasePath('/dist/webawesome');
 // the session.
 registerBundledIcons();
 
-// The touch equivalent of a right-click, installed once for every menu
+// Every touch gesture in the app, installed once rather than per
-// in the app rather than per component. Harmless on a desktop: it acts
+// component (plan 019). Harmless on a desktop: it acts on
-// on `pointerType === 'touch'` only.
+// `pointerType === 'touch'` only, per event, so a mouse on a
-installLongPressContextMenu();
+// touchscreen keeps click-selects / double-click-plays on the very
+// same row. An unclaimed long press still becomes a `contextmenu`,
+// which is what leaves all fourteen menus untouched by #63.
+installTouchGestures();
 
 // The top bar decides what it can afford to show (#143). Here rather
 // than in a component because the bar is light DOM in index.html and

frontend/src/components/artists-view/artists-view.ts

@@ -7,6 +7,7 @@ import {
 import '@lit-labs/virtualizer';
 import type {
     LitVirtualizer,
+    RangeChangedEvent,
     VisibilityChangedEvent,
 } from '@lit-labs/virtualizer';
 import { grid } from '@lit-labs/virtualizer/layouts/grid.js';
@@ -30,6 +31,7 @@ import type { ContextMenuHost, MenuTarget } from '@utils/context-menu-controller
 import { FavoritesController } from '@store/controllers/favorites-controller';
 import { ViewLifecycleMixin } from '@utils/view-lifecycle';
 import { RovingGridController } from '@utils/roving-grid';
+import { prefetchImageWindow } from '@utils/image-prefetch';
 
 import '@awesome.me/webawesome/dist/components/icon/icon.js';
 import '@awesome.me/webawesome/dist/components/popup/popup.js';
@@ -582,6 +584,26 @@ export class ArtistsView
      * Scroll position persistence
      * ================================================================ */
 
+    /**
+     * Warm the avatars just past the rendered range (#65).
+     *
+     * `rangeChanged` is the rendered range and `visibilityChanged` is
+     * what is on screen; the virtualizer has already drawn about
+     * 1000px past the latter, so that is the wrong anchor to measure a
+     * prefetch window from. It is deliberately outside the
+     * `restoringScroll` guard below: a restored scroll lands in the
+     * middle of the grid, which is exactly when nothing around it is
+     * cached.
+     */
+    private onRangeChanged = (e: RangeChangedEvent) => {
+        prefetchImageWindow(
+            this.cachedGridEntries,
+            e.first,
+            e.last,
+            (entry) => this.artistAvatarURL(entry.artist),
+        );
+    };
+
     /**
      * Save the first visible item index on scroll.
      */
@@ -1145,7 +1167,16 @@ export class ArtistsView
      * Helpers
      * ================================================================ */
 
-    private renderArtistAvatar(artist: library.Artist) {
+    /**
+     * The image this artist's card will draw, or `''` for the initial
+     * placeholder.
+     *
+     * Split out of `renderArtistAvatar` so the prefetch (#65) asks for
+     * exactly what the card is going to ask for — a second copy of the
+     * tier ladder would be a second thing to keep in step, and warming
+     * the wrong tier is a download that buys nothing.
+     */
+    private artistAvatarURL(artist: library.Artist): string {
         const needed = (this.imageSize ?? 176) * window.devicePixelRatio;
         let imageURL = '';
 
@@ -1172,6 +1203,12 @@ export class ArtistsView
             ) ?? '';
         }
 
+        return imageURL;
+    }
+
+    private renderArtistAvatar(artist: library.Artist) {
+        const imageURL = this.artistAvatarURL(artist);
+
         if (imageURL) {
             return html`<img
                 class="avatar-image"
@@ -1531,6 +1568,7 @@ export class ArtistsView
                     .keyFunction=${(entry: ArtistEntry) => entry.artist.ID}
                     .layout=${this.gridLayout}
                     @visibilityChanged=${this.onVisibilityChanged}
+                    @rangeChanged=${this.onRangeChanged}
                 ></lit-virtualizer>
             </div>
             ${this.renderContextMenu()}

frontend/src/components/bottom-nav/bottom-nav.ts

@@ -4,6 +4,7 @@ import '@awesome.me/webawesome/dist/components/icon/icon.js';
 import '@awesome.me/webawesome/dist/components/drawer/drawer.js';
 import type WaDrawer from '@awesome.me/webawesome/dist/components/drawer/drawer.js';
 import { designTokens } from '../../styles/tokens.css';
+import { sheetScrollFade } from '../../styles/sheet-scroll.css';
 import '../sidebar/app-sidebar.js';
 import { nameDialog } from '@utils/name-dialog';
 import { ICON_PLAYLIST } from '@utils/icon-language';
@@ -27,15 +28,43 @@ interface Tab {
  * three to five items before the targets stop being thumb-sized —
  * 360 px over eleven sidebar entries is 32 px each — so the four here
  * are the ones plan 016's subset says a phone is *for*, and "More"
- * opens the existing `<app-sidebar>` in a drawer. That is deliberately
+ * opens the existing `<app-sidebar>` in a sheet. That is deliberately
  * a reuse rather than a second nav: two lists of destinations is two
  * places to add the next view to, and the sidebar already carries the
  * drag-to-navigate behaviour, the active state and the labels.
  *
+ * **"More" rises from the bottom, and it is the same sheet a context
+ * menu is** (#71). It was a `wa-drawer` sliding in from the side: a
+ * 200px column of a 424px screen, opening away from the thumb that
+ * asked for it, with three nested scrollers in it — the dialog, its
+ * body, and the sidebar's own `overflow-y: auto` host — which is the
+ * "only part of the screen scrolls under my finger" in the report.
+ *
+ * Three things about the replacement are load-bearing.
+ *
+ * **It is the same element with another `placement`, not a new
+ * surface.** `wa-drawer` renders a native `<dialog>` and opens it with
+ * `showModal()`, which is exactly what `menu-surface`'s sheet relies
+ * on — Chrome 37, the real top layer — so #60's containment finding
+ * carries over with nothing new to prove, and the focus trap, Escape,
+ * tap-outside and `wa-after-hide` all come along unchanged.
+ *
+ * **The body is the only scroller**, with `overscroll-behavior:
+ * contain`, and the sidebar is told to stop being one. Nesting them is
+ * what makes a drag scroll the wrong box.
+ *
+ * **The sidebar is still mounted rather than re-listed as data**,
+ * which the issue offers as an alternative. Its `data-testid` per
+ * destination is the reason: the shell's own sidebar is `display:
+ * none` below 600px rather than removed, so a second list drawing
+ * `nav-*` handles is the duplication this component already renders
+ * conditionally to avoid — and it would be a second place to add the
+ * next view to, with its own copy of #25's visibility filter.
+ *
  * It emits the same bubbling, composed `navigate` event the sidebar
  * does, so `index.ts` needs no knowledge of it, and it listens for that
  * event globally for the same reason the sidebar does: a navigation it
- * did not send (a card click, a detail view, the drawer) still has to
+ * did not send (a card click, a detail view, the sheet) still has to
  * move the highlight.
  */
 @customElement('bottom-nav')
@@ -89,6 +118,17 @@ export class BottomNav extends LitElement {
             color: var(--yj-accent, #ffd43b);
         }
 
+        /* The press state (#54). This bar is the phone's primary
+           navigation and had no feedback of its own at all -- what a
+           tap produced was the web view's tap highlight, a grey box
+           over the whole 48px cell, which index.css has now taken
+           away. The .active rule above is which tab you are *on*; this
+           is the tab being pressed, so they are a colour and a
+           background rather than two colours. */
+        button:active {
+            background-color: var(--yj-press-overlay, rgba(255, 255, 255, 0.12));
+        }
+
         button:focus-visible {
             outline: 2px solid var(--yj-accent, #ffd43b);
             outline-offset: -2px;
@@ -104,15 +144,76 @@ export class BottomNav extends LitElement {
             white-space: nowrap;
         }
 
-        wa-drawer::part(body) {
+        /* The sheet. --size is the drawer's own API for the axis its
-            padding: 0;
+           placement uses, so auto is what makes it hug its content
+           instead of being a fixed 25rem band; the rest is the shape
+           the menu-surface context sheet already has, so a phone meets
+           one sheet rather than two. 85vh for its reason too: a surface
+           covering the whole screen is a page, not a sheet. */
+        wa-drawer {
+            --size: auto;
         }
 
+        wa-drawer::part(dialog) {
+            max-height: 85vh;
+            border-radius: 12px 12px 0 0;
+            /* The sidebar paints its own surface, so the sheet takes
+               that colour rather than the menus' elevated one: two
+               greys in one sheet is a seam across the middle of it. */
+            background-color: var(--yj-bg-surface, #212529);
+            /* One scroller, and it is the body below. The dialog's own
+               overflow: auto is what let the sheet scroll as well as
+               its content, and it is also what would square off the
+               corners this rule just rounded. */
+            overflow: hidden;
+        }
+
+        /* And this list does not fit (#210): measured at 424x439 with
+           the seed's eight destinations, the body is scrollHeight 412
+           against clientHeight 373, and eleven items at 48px would be
+           528 -- the count is the user's since #25. So the sheet says
+           where the fold is, with styles/sheet-scroll.css's two layers
+           rather than a second answer to the question #207 settled for
+           the context sheet. The colour is the local half: the sidebar
+           paints --yj-bg-surface, so the cover does too, or the fade
+           draws the menus' grey across the bottom of this one. */
+        wa-drawer::part(body) {
+            padding: 0;
+            /* A scroll that reaches the end of this list must not
+               become a scroll of the page underneath it. */
+            overscroll-behavior: contain;
+            /* The sheet sits on the bottom edge, so the last
+               destination would otherwise be under the home indicator
+               on a gesture-navigation phone -- the same allowance the
+               bar itself makes above. */
+            padding-bottom: env(safe-area-inset-bottom, 0);
+            --yj-sheet-surface: var(--yj-bg-surface, #212529);
+            ${sheetScrollFade}
+        }
+
+        /* And the sheet paints that surface once. The sidebar's host
+           paints the same grey -- which in the shell is the sidebar's
+           own background and here is a second, opaque copy of the
+           sheet's, drawn *over* the body's layers. So the fade was
+           painted and then covered: measured at 424x439 before this
+           rule, the last 32px read a flat 52,58,64 with 39px still
+           below. menu-surface meets the same requirement from the
+           other side, where .context-menu-panel[data-sheet] is
+           background-color: transparent; nothing changes visually
+           here, because the colour underneath is the one being
+           removed. */
         app-sidebar {
-            /* The sidebar sizes itself inline and collapses to icons
+            background-color: transparent;
-               below 900px, which is every phone.  In the drawer there
+        }
-               is room for the labels, so it is told not to. */
+
-            height: 100%;
+        /* A sheet is dragged at with a thumb, so it says where its top
+           edge is. Decorative: the destinations are below it. */
+        .grip {
+            width: 36px;
+            height: 4px;
+            margin: 8px auto 4px;
+            border-radius: 2px;
+            background: var(--yj-text-tertiary, #888);
         }
     `];
 
@@ -147,7 +248,7 @@ export class BottomNav extends LitElement {
     private visibilityCtrl = new ViewVisibilityController(this);
 
     /**
-     * Whether the drawer has been asked for.
+     * Whether the sheet has been asked for.
      *
      * The sidebar inside it is rendered only while this is true, and
      * that is not an optimisation. `app-sidebar` carries a
@@ -189,15 +290,17 @@ export class BottomNav extends LitElement {
 
     override updated() {
         // Web Awesome renders its heading into its own shadow root and
-        // never points aria-labelledby at it, so the drawer would
+        // never points aria-labelledby at it, so the sheet would
         // otherwise be announced unnamed -- the same fix, and the same
         // reason, as every wa-dialog in the app. A drawer's shadow root
-        // has the same shape, so the helper needs no change.
+        // has the same shape, so the helper needs no change; under
+        // `without-header` there is no heading to point at, which is
+        // that helper's documented `aria-label` path.
         nameDialog(this.drawer);
     }
 
     private onGlobalNavigate = () => {
-        // A navigation from inside the drawer is the drawer's job done.
+        // A navigation from inside the sheet is the sheet's job done.
         // The highlight is not this listener's business any more.
         this.drawerOpen = false;
     };
@@ -263,12 +366,14 @@ export class BottomNav extends LitElement {
             </nav>
 
             <wa-drawer
-                placement="start"
+                placement="bottom"
+                without-header
                 label="All views"
                 data-testid="nav-drawer"
                 ?open=${this.drawerOpen}
                 @wa-after-hide=${this.onDrawerHide}
             >
+                <div class="grip"></div>
                 ${this.drawerOpen
                     ? html`<app-sidebar expanded></app-sidebar>`
                     : nothing}

frontend/src/components/cover-grid/cover-grid.ts

@@ -8,6 +8,7 @@ import {
 import '@lit-labs/virtualizer';
 import type {
     LitVirtualizer,
+    RangeChangedEvent,
     VisibilityChangedEvent,
 } from '@lit-labs/virtualizer';
 import { grid } from '@lit-labs/virtualizer/layouts/grid.js';
@@ -30,6 +31,7 @@ import '@awesome.me/webawesome/dist/components/icon/icon.js';
 import '@components/playlist-picker/playlist-picker.js';
 import { loadTrackDetails } from '@utils/lazy-track-details.js';
 import { tracksByFilePath, tracksForPaths } from '@utils/track-index.js';
+import { prefetchImageWindow } from '@utils/image-prefetch.js';
 import type { TrackDetails } from '@components/track-details/track-details.js';
 import type { CoverArtUrls } from '@components/track-details/track-details.js';
 import { AlbumSelectionManager } from './album-selection.js';
@@ -55,6 +57,8 @@ import {
 import type { ContextMenuHost, MenuTarget } from '@utils/context-menu-controller.js';
 import { FavoritesController } from '@store/controllers/favorites-controller';
 import { creditLink, exploreLinkStyles } from '../../utils/explore-link';
+import { goToMenuItems } from '../../utils/go-to-menu';
+import type { GoToTarget } from '../../utils/go-to-menu';
 import { creditStore } from '@store/credit-store';
 import {
     createAlbumArtDragImage,
@@ -908,6 +912,31 @@ export class CoverGrid
         );
     };
 
+    /**
+     * Warm the covers just past the rendered range (#65).
+     *
+     * `rangeChanged` rather than `visibilityChanged`, because the two
+     * report different ranges and only one of them is the right
+     * anchor: visibility is what is on screen, and the virtualizer has
+     * already rendered about 1000px past that. Measured from the
+     * visible range this would spend most of its window on cards that
+     * already exist and have already asked for their own art.
+     *
+     * The entry lists are memoized, so asking for one here costs a
+     * reference compare.
+     */
+    private onRangeChanged = (e: RangeChangedEvent) => {
+        const entries = this.splitMode
+            ? this.getBeforeEntries()
+            : this.buildGridEntries();
+
+        prefetchImageWindow(entries, e.first, e.last, (entry) =>
+            entry.album.CoverArtPath
+                ? this.getCoverUrl(entry.album)
+                : '',
+        );
+    };
+
     /* ====================================================================
      * Virtualizer items
      * ==================================================================== */
@@ -2001,6 +2030,7 @@ export class CoverGrid
                 @keydown=${this.onGridAlbumKeydown}
                 @contextmenu=${this.onGridAlbumContextMenu}
                 @visibilityChanged=${this.onVisibilityChanged}
+                @rangeChanged=${this.onRangeChanged}
             ></lit-virtualizer>
         `;
     }
@@ -2035,6 +2065,7 @@ export class CoverGrid
                 @keydown=${this.onGridAlbumKeydown}
                 @contextmenu=${this.onGridAlbumContextMenu}
                 @visibilityChanged=${this.onVisibilityChanged}
+                @rangeChanged=${this.onRangeChanged}
             ></lit-virtualizer>
 
             <album-dropdown
@@ -2084,6 +2115,30 @@ export class CoverGrid
         );
     }
 
+    /**
+     * The artist an album card's menu can navigate to — the card's own
+     * credit line, which stops being a link below the phone breakpoint
+     * (#67).
+     *
+     * A *track* target gets nothing: the dropdown's rows carry no
+     * links of their own, and the album they sit under is the card
+     * that opened them.
+     */
+    private get goToTarget(): GoToTarget | undefined {
+        if (this.contextMenuTarget.kind !== 'album') return undefined;
+
+        const album = this.albums.find(
+            (a) => a.ID === this.contextMenuAlbumId,
+        );
+
+        if (!album) return undefined;
+
+        return {
+            artistName: album.ArtistName,
+            artistMBID: album.ArtistMBID,
+        };
+    }
+
     private renderContextMenu() {
         const { ctxMenu } = this;
 
@@ -2199,6 +2254,11 @@ export class CoverGrid
                                         </wa-dropdown-item>
                                     `
                                   : nothing}
+                              ${goToMenuItems(this.goToTarget, {
+                                  onSelect: () => ctxMenu.close(),
+                                  onHover: () =>
+                                      ctxMenu.closePlaylistSubmenu(),
+                              })}
                           </div>
                       `
                 : nothing}

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

@@ -3191,10 +3191,14 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
         return html`
             ${artist
                 ? html`<div class="album-artist">
+                      <!-- keepOnPhone: the page header is not a row and
+                           has no menu of its own, so this credit is the
+                           only route from an album to its artist (#67). -->
                       ${creditLink(
                           creditStore.credits(this.releaseGroupMBID),
                           artist,
                           artistMbid,
+                          { keepOnPhone: true },
                       )}
                   </div>`
                 : nothing}

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

@@ -30,6 +30,7 @@ import { libraryStore } from '../../store/library-store';
 import { downloadStore } from '../../store/download-store';
 import '@awesome.me/webawesome/dist/components/button/button.js';
 import { trackLink, exploreLinkStyles } from '../../utils/explore-link';
+import { goToMenuItems } from '../../utils/go-to-menu';
 import { describeError } from '../../utils/describe-error';
 import {
     GetAlbumsByArtist,
@@ -2705,6 +2706,16 @@ export class ExploreArtistDetails extends LitElement implements ContextMenuHost
                 <wa-icon slot="icon" name="globe"></wa-icon>
                 View on MusicBrainz
             </wa-dropdown-item>
+            <!-- The track title links to its album, and below the phone
+                 breakpoint it is plain text (#67). The artist is this
+                 page, so there is nothing to go to. -->
+            ${goToMenuItems(
+                { albumName: track.releaseName, albumMBID: track.releaseGroupMbid ?? '' },
+                {
+                    onSelect: () => this.ctxMenu.close(),
+                    onHover: () => this.ctxMenu.closePlaylistSubmenu(),
+                },
+            )}
         `;
     }
 

frontend/src/components/explore-view/explore-view.ts

@@ -23,6 +23,8 @@ import { queueStore } from '../../store/queue-store';
 import { notificationStore } from '../../store/notification-store';
 import '../notifications/inline-notice';
 import { creditLink, trackLink, exploreLinkStyles } from '../../utils/explore-link';
+import { goToMenuItems } from '../../utils/go-to-menu';
+import type { GoToTarget } from '../../utils/go-to-menu';
 import { creditStore } from '@store/credit-store';
 import { describeError } from '../../utils/describe-error';
 import '@awesome.me/webawesome/dist/components/icon/icon.js';
@@ -54,10 +56,28 @@ export const ExploreRegion = 'explore';
  * is present only when owned — that's what gates the playback items,
  * while `mbid` (always present) is what "View on MusicBrainz" uses, so
  * a catalog-only card still gets a menu with somewhere useful to go.
+ *
+ * `goTo` is the names the card draws -- an artist credit, and for a
+ * recording row the release its title links to. Below the phone
+ * breakpoint those are plain text, so the menu is where they went
+ * (#67); an album card carries no album of its own, because tapping
+ * the card is already that.
  */
 type ExploreMenuTarget =
-    | { kind: 'album'; mbid: string; localId?: number; title: string }
+    | {
-    | { kind: 'recording'; mbid: string; localId?: number; title: string };
+          kind: 'album';
+          mbid: string;
+          localId?: number;
+          title: string;
+          goTo?: GoToTarget;
+      }
+    | {
+          kind: 'recording';
+          mbid: string;
+          localId?: number;
+          title: string;
+          goTo?: GoToTarget;
+      };
 type ThumbnailRequest = explore.ThumbnailRequest;
 type MBSearchResult = explore.MBSearchResult;
 type LyricsResult = explore.LyricsResult;
@@ -1386,6 +1406,9 @@ export class ExploreView extends ViewLifecycleMixin(LitElement) implements Conte
                                   <wa-icon slot="icon" name="globe"></wa-icon>
                                   View on MusicBrainz
                               </wa-dropdown-item>
+                              ${goToMenuItems(target.goTo, {
+                                  onSelect: () => this.ctxMenu.close(),
+                              })}
                           </div>
                       `
                     : nothing}
@@ -2188,6 +2211,10 @@ export class ExploreView extends ViewLifecycleMixin(LitElement) implements Conte
                                         mbid: rg.mbid,
                                         localId: rg.localId,
                                         title: rg.title,
+                                        goTo: {
+                                            artistName: rg.artistCredit,
+                                            artistMBID: rg.artistMbid ?? '',
+                                        },
                                     })}
                                 role="button"
                                 tabindex="0"
@@ -2200,6 +2227,10 @@ export class ExploreView extends ViewLifecycleMixin(LitElement) implements Conte
                                             mbid: rg.mbid,
                                             localId: rg.localId,
                                             title: rg.title,
+                                            goTo: {
+                                                artistName: rg.artistCredit,
+                                                artistMBID: rg.artistMbid ?? '',
+                                            },
                                         },
                                     )}
                             >
@@ -2278,6 +2309,12 @@ export class ExploreView extends ViewLifecycleMixin(LitElement) implements Conte
                                         mbid: r.mbid,
                                         localId: r.localId,
                                         title: r.title,
+                                        goTo: {
+                                            artistName: r.artistCredit,
+                                            artistMBID: r.artistMbid ?? '',
+                                            albumName: r.releaseName ?? '',
+                                            albumMBID: r.releaseGroupMbid ?? '',
+                                        },
                                     })}
                                 @keydown=${(e: KeyboardEvent) =>
                                     this.onCardKeydown(
@@ -2288,6 +2325,12 @@ export class ExploreView extends ViewLifecycleMixin(LitElement) implements Conte
                                             mbid: r.mbid,
                                             localId: r.localId,
                                             title: r.title,
+                                            goTo: {
+                                                artistName: r.artistCredit,
+                                                artistMBID: r.artistMbid ?? '',
+                                                albumName: r.releaseName ?? '',
+                                                albumMBID: r.releaseGroupMbid ?? '',
+                                            },
                                         },
                                     )}
                             >

frontend/src/components/home-view/home-view.ts

@@ -166,7 +166,7 @@ export class HomeView extends ViewLifecycleMixin(LitElement) {
              * gated on the device having hover rather than on width.  A
              * touch long-press synthesises a hover state in the WebView,
              * so on a phone it flashed into view during the 500ms hold
-             * that utils/long-press.ts is measuring for a context menu —
+             * that utils/touch-gestures.ts is measuring for a long press —
              * a control appearing because you were reaching for a
              * different one.  A phone user taps the album and plays from
              * the detail view, so there is nothing to replace it with.

frontend/src/components/menu-surface/menu-surface.ts

@@ -65,6 +65,7 @@ import '@awesome.me/webawesome/dist/components/popup/popup.js';
 import '@awesome.me/webawesome/dist/components/dialog/dialog.js';
 import type WaPopup from '@awesome.me/webawesome/dist/components/popup/popup.js';
 
+import { sheetScrollFade } from '../../styles/sheet-scroll.css';
 import { PHONE_QUERY } from '@utils/breakpoints';
 import { nameDialogsIn } from '@utils/name-dialog';
 
@@ -155,10 +156,26 @@ export class MenuSurface extends LitElement {
            bottom was at y=452 on a 439px screen -- the one row a
            destructive action is most likely to be. The cap has to stay
            (a sheet covering the whole screen is a page, not a sheet),
-           so the body is what gives. */
+           so the body is what gives.
+
+           **And a body that scrolls says so** (#207). Scrolling was the
+           whole of the fix above, which left the last item reachable
+           and nothing on screen admitting it was there -- measured at
+           424x439, eight items ending at y=470 with the fold at 439,
+           and worse when the cut lands on a row boundary, where the
+           sheet ends in a clean edge that reads as the end of the list.
+
+           The two layers that say it live in styles/sheet-scroll.css
+           (#210), because the phone has a second sheet -- bottom-nav's
+           "More" -- which overflows for the same reason and must not
+           arrive at its own answer for what a fold looks like. What is
+           local to this sheet is the colour the cover is painted in:
+           the menus' elevated grey, handed over as --yj-sheet-surface
+           on the same box. */
         wa-dialog::part(body) {
             padding: 0;
-            overflow-y: auto;
+            --yj-sheet-surface: var(--yj-bg-elevated, #343a40);
+            ${sheetScrollFade}
         }
 
         /* A sheet is dragged at with a thumb, so it says where its top

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

@@ -420,11 +420,20 @@ export class NowPlayingView extends LitElement {
                         <h2 class="title" data-testid="npv-title">
                             ${track.title || track.fileName}
                         </h2>
+                        <!-- keepOnPhone: this screen is the phone's,
+                             and it has no context menu to carry the
+                             destination the way a row does (#67).
+                             Suppressing these takes the artist and the
+                             album away rather than moving them, and
+                             they are two lines of their own here
+                             rather than a few characters inside a
+                             row. -->
                         <p class="artist">
                             ${creditLink(
                                 creditStore.credits(track.recordingMbid),
                                 track.artist,
                                 track.artistMbid,
+                                { keepOnPhone: true },
                             )}
                         </p>
                         ${track.album
@@ -434,6 +443,7 @@ export class NowPlayingView extends LitElement {
                                       track.releaseGroupMbid,
                                       undefined,
                                       track.artist,
+                                      { keepOnPhone: true },
                                   )}
                               </p>`
                             : nothing}

frontend/src/components/playlist-details/playlist-details.ts

@@ -38,6 +38,10 @@ import {
 } from '@utils/context-menu-controller.js';
 import type { ContextMenuHost, MenuTarget } from '@utils/context-menu-controller.js';
 import { focusRovingRow, nextRovingIndex } from '@utils/roving-rows';
+import type { GestureEvent } from '@utils/touch-gestures';
+import { SwipeToQueue, swipeRevealStyles } from '@utils/swipe-to-queue';
+import '@components/selection-bar/selection-bar';
+import type { SelectionAction } from '@components/selection-bar/selection-bar';
 import { FavoritesController } from '@store/controllers/favorites-controller';
 import { notificationStore } from '@store/notification-store';
 import { describeError } from '@utils/describe-error';
@@ -70,12 +74,17 @@ import {
     trackLink,
     exploreLinkStyles,
 } from '@utils/explore-link';
+import { goToMenuItems } from '@utils/go-to-menu';
+import type { GoToTarget } from '@utils/go-to-menu';
 import { designTokens } from '../../styles/tokens.css';
+import { srOnly } from '../../styles/sr-only.css';
 import { backButton } from '../../styles/back-button.css';
 import { list } from '@utils/binding';
 import {
+    ICON_PLAY,
     ICON_PLAYLIST,
     ICON_QUEUE,
+    ICON_REMOVE,
 } from '@utils/icon-language';
 
 /** One playlist row: the track and its position in the *playlist*,
@@ -422,6 +431,127 @@ export class PlaylistDetails
         queueStore.setQueue(filePaths, trackIndex, false, { type: 'playlist', id: this.playlistId, label: this.playlistName });
     }
 
+    // =================================================================
+    // A finger on a playlist row (plan 019 phase 3, #63)
+    // =================================================================
+
+    /** The row an announced gesture is on, with its track. */
+    private rowFromGesture(
+        e: Event,
+    ): { index: number; track: playlist.Track } | null {
+        const row = (e.target as HTMLElement).closest(
+            '.track-item',
+        ) as HTMLElement | null;
+
+        if (!row) return null;
+
+        const index = Number(row.dataset.index);
+        const track = this.tracks[index];
+
+        if (Number.isNaN(index) || !track) return null;
+
+        return { index, track };
+    }
+
+    /**
+     * A tap plays the playlist from that row.
+     *
+     * The same thing a double-click does, which is the rule the whole
+     * app follows: activating one row plays the list the row is in,
+     * from that row, rather than a queue of one that stops when the
+     * song ends.
+     */
+    private onRowTap = (e: GestureEvent) => {
+        const hit = this.rowFromGesture(e);
+
+        if (!hit) return;
+
+        if (this.selection.selectionMode) {
+            e.preventDefault();
+            this.focusedIndex = hit.index;
+            this.selection.toggleInMode(String(hit.index), hit.index);
+            this.virtualizer?.requestUpdate();
+
+            return;
+        }
+
+        // A missing file has nothing to play, so the tap is left
+        // unclaimed and falls through to the click that selects it --
+        // which is what a mouse does here and the only useful thing a
+        // phantom row can answer.
+        if (hit.track.Phantom) return;
+
+        e.preventDefault();
+        this.focusedIndex = hit.index;
+        this.handleTrackDblClick(hit.index);
+    };
+
+    private onRowLongPress = (e: GestureEvent) => {
+        const hit = this.rowFromGesture(e);
+
+        if (!hit) return;
+
+        e.preventDefault();
+        this.focusedIndex = hit.index;
+        this.selection.enterSelectionMode(String(hit.index), hit.index);
+        this.virtualizer?.requestUpdate();
+    };
+
+    /**
+     * Swipe a row right to queue it.
+     *
+     * `track-list`'s rule, one list over: one row is a position and
+     * several rows are an explicit choice, and a swipe never changes
+     * the selection it reads.
+     */
+    private swipe = new SwipeToQueue(this, {
+        resolve: (e) => {
+            const hit = this.rowFromGesture(e);
+
+            // A phantom has no file to queue, so there is nothing for
+            // the reveal to promise.
+            if (!hit || hit.track.Phantom) return null;
+
+            const selected = this.selection.getSelectedIndices();
+            const many =
+                selected.length > 1 && selected.includes(hit.index);
+            const filePaths = many
+                ? this.getSelectedFilePaths()
+                : [hit.track.FilePath];
+
+            return { index: hit.index, filePaths, label: hit.track.Title };
+        },
+        repaint: () => this.virtualizer?.requestUpdate(),
+    });
+
+    /** The three worth a thumb; the sheet behind "More" is the rest. */
+    private static readonly SELECTION_ACTIONS: SelectionAction[] = [
+        { id: 'play', label: 'Play', icon: ICON_PLAY },
+        { id: 'add-to-queue', label: 'Add to queue', icon: ICON_QUEUE },
+        { id: 'remove', label: 'Remove', icon: ICON_REMOVE, danger: true },
+    ];
+
+    private renderSelectionBar() {
+        if (!this.selection.selectionMode) return nothing;
+
+        return html`
+            <selection-bar
+                .count=${this.selection.selectionCount}
+                .actions=${PlaylistDetails.SELECTION_ACTIONS}
+                @selection-exit=${this.onSelectionExit}
+                @selection-action=${(e: CustomEvent<{ id: string }>) =>
+                this.onContextMenuAction(e.detail.id)}
+                @selection-more=${(e: CustomEvent<{ x: number; y: number }>) =>
+                this.ctxMenu.openAt(e.detail.x, e.detail.y)}
+            ></selection-bar>
+        `;
+    }
+
+    private onSelectionExit = () => {
+        this.selection.exitSelectionMode();
+        this.virtualizer?.requestUpdate();
+    };
+
     private handleTrackContextMenu(
         e: MouseEvent,
         trackIndex: number,
@@ -461,6 +591,28 @@ export class PlaylistDetails
             .map((i) => this.tracks[i]!.FilePath);
     }
 
+    /**
+     * The row "Go to Artist" / "Go to Album" navigate from — one row
+     * or none, and only below the phone breakpoint, where the row's
+     * own names stopped being links (#67).
+     */
+    private get goToTarget(): GoToTarget | undefined {
+        const indices = this.selection.getSelectedIndices();
+
+        if (indices.length !== 1) return undefined;
+
+        const track = this.tracks[indices[0]!];
+
+        if (!track) return undefined;
+
+        return {
+            artistName: track.Artist,
+            artistMBID: track.ArtistMBID,
+            albumName: track.Album,
+            albumMBID: track.ReleaseGroupMBID,
+        };
+    }
+
     // =================================================================
     // Context menu actions
     // =================================================================
@@ -955,9 +1107,11 @@ export class PlaylistDetails
 
     static override styles = [
         designTokens,
+        srOnly,
         backButton,
         contextMenuStyles,
         exploreLinkStyles,
+        swipeRevealStyles,
         css`
         :host {
             display: flex;
@@ -1136,6 +1290,9 @@ export class PlaylistDetails
         .track-item {
             width: 100%;
             box-sizing: border-box;
+            /* The swipe reveal is absolute inside the row. */
+            position: relative;
+            overflow: hidden;
         }
 
         .track-header {
@@ -1200,8 +1357,14 @@ export class PlaylistDetails
             user-select: none;
         }
 
-        .track-item:hover {
+        /* A hover tint is for a device that hovers (#54). A hold
-            background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+           synthesises a hover in the WebView, so ungated this arrives
+           because a finger touched the row and stays after it has
+           gone; the press state below is what a tap gets instead. */
+        @media (hover: hover) and (pointer: fine) {
+            .track-item:hover {
+                background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+            }
         }
 
         .track-item.selected {
@@ -1221,11 +1384,13 @@ export class PlaylistDetails
             cursor: pointer;
         }
 
-        .track-item.phantom:hover {
+        @media (hover: hover) and (pointer: fine) {
-            background-color: var(
+            .track-item.phantom:hover {
-                --yj-hover-overlay,
+                background-color: var(
-                rgba(255, 255, 255, 0.05)
+                    --yj-hover-overlay,
-            );
+                    rgba(255, 255, 255, 0.05)
+                );
+            }
         }
 
         .track-item.phantom.selected {
@@ -1235,6 +1400,19 @@ export class PlaylistDetails
             );
         }
 
+        /* The press state (#54): the feedback a tap has now that the
+           web view's own highlight box is gone (index.css). Last, and
+           carrying a class, because a selected or playing row is two
+           classes deep and a bare :active would lose to it. */
+        .track-item.selected:active,
+        .track-item.active:active,
+        .track-item:active {
+            background-color: var(
+                --yj-press-overlay,
+                rgba(255, 255, 255, 0.12)
+            );
+        }
+
         .phantom-row {
             grid-column: 1 / -1;
             display: flex;
@@ -1433,6 +1611,9 @@ export class PlaylistDetails
                 <div class="header-cell col-album">Album</div>
                 <div class="header-cell col-duration">Duration</div>
             </div>
+            <div class="sr-only" role="status" aria-live="polite">
+                ${this.swipe.announcement}
+            </div>
             <lit-virtualizer
                 class="track-scroller"
                 role="listbox"
@@ -1442,7 +1623,13 @@ export class PlaylistDetails
                 .renderItem=${this.renderRow}
                 .keyFunction=${this.rowKey}
                 .layout=${this.flowLayout}
+                @yj-tap=${this.onRowTap}
+                @yj-long-press=${this.onRowLongPress}
+                @yj-swipe-start=${this.swipe.onSwipeStart}
+                @yj-swipe-move=${this.swipe.onSwipeMove}
+                @yj-swipe-end=${this.swipe.onSwipeEnd}
             ></lit-virtualizer>
+            ${this.renderSelectionBar()}
         `;
     }
 
@@ -1464,6 +1651,7 @@ export class PlaylistDetails
                         active ? 'active' : '',
                         selected ? 'selected' : '',
                         isPhantom ? 'phantom' : '',
+                        this.swipe.isSwiping(trackIndex) ? 'swiping' : '',
                     ]
                         .filter(Boolean)
                         .join(' ');
@@ -1474,6 +1662,7 @@ export class PlaylistDetails
                             role="option"
                             aria-selected=${selected}
                             data-index=${trackIndex}
+                            data-swipe
                             tabindex=${trackIndex === this.focusedIndex ? 0 : -1}
                             @keydown=${(e: KeyboardEvent) =>
                                 this.onRowKeydown(e, trackIndex)}
@@ -1520,6 +1709,7 @@ export class PlaylistDetails
                                 ? nothing
                                 : this.onTrackDragEnd}
                         >
+                            ${this.swipe.renderReveal(trackIndex)}
                             ${isPhantom
                                 ? html`<div
                                       class="phantom-row"
@@ -1755,6 +1945,14 @@ export class PlaylistDetails
                                       Track
                                       Details
                                   </wa-dropdown-item>
+                                  ${goToMenuItems(this.goToTarget, {
+                                      onSelect: () => {
+                                          this.selection.clear();
+                                          this.ctxMenu.close();
+                                      },
+                                      onHover: () =>
+                                          this.ctxMenu.closePlaylistSubmenu(),
+                                  })}
                               </div>
                           `
                     : nothing}

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

@@ -62,11 +62,18 @@ import {
     trackLink,
     exploreLinkStyles,
 } from '@utils/explore-link';
+import { goToMenuItems } from '@utils/go-to-menu';
+import type { GoToTarget } from '@utils/go-to-menu';
 import {
     ICON_NEW,
+    ICON_PLAY,
     ICON_PLAYLIST,
     ICON_QUEUE,
+    ICON_REMOVE,
 } from '@utils/icon-language';
+import type { GestureEvent } from '@utils/touch-gestures';
+import '@components/selection-bar/selection-bar';
+import type { SelectionAction } from '@components/selection-bar/selection-bar';
 /** Above this many tracks, clearing the queue asks first. */
 const CLEAR_CONFIRM_THRESHOLD = 20;
 
@@ -574,8 +581,14 @@ export class QueuePanel
             contain: strict;
         }
 
-        .track-item:hover {
+        /* A hover tint is for a device that hovers (#54). A hold
-            background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+           synthesises a hover in the WebView, so ungated this arrives
+           because a finger touched the row and stays after it has
+           gone; the press state below is what a tap gets instead. */
+        @media (hover: hover) and (pointer: fine) {
+            .track-item:hover {
+                background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+            }
         }
 
         .track-item.selected {
@@ -590,6 +603,19 @@ export class QueuePanel
             background-color: var(--yj-selection-bg, rgba(100, 160, 255, 0.15));
         }
 
+        /* The press state (#54): the feedback a tap has now that the
+           web view's own highlight box is gone (index.css). Last, and
+           carrying a class, because a selected or playing row is two
+           classes deep and a bare :active would lose to it. */
+        .track-item.selected:active,
+        .track-item.active:active,
+        .track-item:active {
+            background-color: var(
+                --yj-press-overlay,
+                rgba(255, 255, 255, 0.12)
+            );
+        }
+
         .track-position {
             font-size: var(--yj-text-sm);
             color: var(--yj-text-tertiary, #888);
@@ -844,6 +870,8 @@ export class QueuePanel
         virtEl.addEventListener('dragstart', this.onDelegatedDragStart);
         virtEl.addEventListener('dragend', this.onTrackDragEnd);
         virtEl.addEventListener('keydown', this.onDelegatedKeydown);
+        virtEl.addEventListener('yj-tap', this.onRowTap);
+        virtEl.addEventListener('yj-long-press', this.onRowLongPress);
         this.delegationAttached = true;
     }
 
@@ -962,6 +990,8 @@ export class QueuePanel
             virtEl.removeEventListener('dragstart', this.onDelegatedDragStart);
             virtEl.removeEventListener('dragend', this.onTrackDragEnd);
             virtEl.removeEventListener('keydown', this.onDelegatedKeydown);
+            virtEl.removeEventListener('yj-tap', this.onRowTap);
+            virtEl.removeEventListener('yj-long-press', this.onRowLongPress);
         }
         this.delegationAttached = false;
     }
@@ -1247,6 +1277,92 @@ export class QueuePanel
         this.queue.playAtIndex(index);
     }
 
+    // =================================================================
+    // A finger on a queue row (plan 019 phase 3, #63)
+    // =================================================================
+
+    /**
+     * A tap plays this position in the queue.
+     *
+     * `track-list`'s tap sets the queue to the list it was made in;
+     * copying that here would rebuild the queue from the queue, which
+     * is not the no-op it looks like -- it would discard the queue's
+     * source, its shuffle order and everything a user had inserted by
+     * hand. `playAtIndex` is what a double-click already does, and it
+     * is what a tap means.
+     */
+    private onRowTap = (e: GestureEvent) => {
+        const idx = this.resolveTrackIndexFromEvent(e);
+
+        if (idx === null) return;
+
+        // A control inside the row owns its own tap -- the same rule
+        // the shortcut service has for a focused control that owns a
+        // key. The remove button is the one here.
+        if ((e.target as HTMLElement).closest('.remove-button')) return;
+
+        e.preventDefault();
+
+        // The roving tab stop follows the finger, or Tab returns to
+        // wherever the arrows last were rather than to the row that was
+        // just touched.
+        this.focusedIndex = idx;
+
+        if (this.selection.selectionMode) {
+            this.selection.toggleInMode(String(idx), idx);
+            this.virtualizer?.requestUpdate();
+
+            return;
+        }
+
+        this.selection.clear();
+        this.queue.playAtIndex(idx);
+    };
+
+    private onRowLongPress = (e: GestureEvent) => {
+        const idx = this.resolveTrackIndexFromEvent(e);
+
+        if (idx === null) return;
+
+        e.preventDefault();
+        this.focusedIndex = idx;
+        this.selection.enterSelectionMode(String(idx), idx);
+        this.virtualizer?.requestUpdate();
+    };
+
+    /**
+     * The two worth a thumb, and "More" for the rest.
+     *
+     * Remove is here rather than left to the overflow because it is
+     * what a selection in a *queue* is most often made for, and it is
+     * the action the row's own × offers one row at a time.
+     */
+    private static readonly SELECTION_ACTIONS: SelectionAction[] = [
+        { id: 'play', label: 'Play', icon: ICON_PLAY },
+        { id: 'remove', label: 'Remove', icon: ICON_REMOVE, danger: true },
+    ];
+
+    private renderSelectionBar() {
+        if (!this.selection.selectionMode) return nothing;
+
+        return html`
+            <selection-bar
+                .count=${this.selection.selectionCount}
+                .actions=${QueuePanel.SELECTION_ACTIONS}
+                @selection-exit=${this.onSelectionExit}
+                @selection-action=${(e: CustomEvent<{ id: string }>) =>
+                this.onContextMenuAction(e.detail.id)}
+                @selection-more=${(e: CustomEvent<{ x: number; y: number }>) =>
+                this.ctxMenu.openAt(e.detail.x, e.detail.y)}
+            ></selection-bar>
+        `;
+    }
+
+    private onSelectionExit = () => {
+        this.selection.exitSelectionMode();
+        this.virtualizer?.requestUpdate();
+    };
+
     private handleTrackContextMenu(
         e: MouseEvent,
         index: number,
@@ -1529,6 +1645,29 @@ export class QueuePanel
             .map((i) => tracks[i]!.filePath);
     }
 
+    /**
+     * The row "Go to Artist" / "Go to Album" navigate from, which is
+     * one row or none — the rule the Play item already follows.  Both
+     * items are drawn only below the phone breakpoint, where the row's
+     * own names stopped being links (#67).
+     */
+    private get goToTarget(): GoToTarget | undefined {
+        const indices = this.selection.getSelectedIndices();
+
+        if (indices.length !== 1) return undefined;
+
+        const track = this.queue.tracks[indices[0]!];
+
+        if (!track) return undefined;
+
+        return {
+            artistName: track.artist,
+            artistMBID: track.artistMbid,
+            albumName: track.album,
+            albumMBID: track.releaseGroupMbid,
+        };
+    }
+
     // =================================================================
     // Drop target (tracks dropped into queue)
     // =================================================================
@@ -2062,11 +2201,25 @@ export class QueuePanel
                             `
                             : nothing}
                     </div>
+                    <!-- **Every action here is named by aria-label**, like
+                         the close button #24 added beside them (#170). A
+                         title alone *is* a name, which is why a sweep for
+                         empty names reports these clean and why an
+                         assertion by role and name is green either way --
+                         but it is the weakest one: title is the last
+                         fallback in the accname order, so any content put
+                         inside the button later silently outranks it, and
+                         a phone has no hover to show it as a tooltip.
+
+                         The titles stay. On a desktop they are the tooltip
+                         for an icon-only control, which is a different job
+                         from naming it, and aria-label does not do it. -->
                     <div class="header-actions">
                         <button
                             class="header-action-button"
                             @click=${() => void this.handleClearQueue()}
                             ?disabled=${tracks.length === 0}
+                            aria-label="Clear queue"
                             title="Clear queue"
                         >
                             <wa-icon
@@ -2077,6 +2230,7 @@ export class QueuePanel
                             class="header-action-button add-to-playlist-button"
                             @click=${this.handleAddToPlaylist}
                             ?disabled=${tracks.length === 0}
+                            aria-label="Add queue to playlist"
                             title="Add queue to playlist"
                         >
                             <wa-icon
@@ -2157,6 +2311,7 @@ export class QueuePanel
                               ></lit-virtualizer>
                           `}
                 </div>
+                ${this.renderSelectionBar()}
             </div>
 
             <menu-surface
@@ -2245,6 +2400,14 @@ export class QueuePanel
                                   Track
                                   Details
                               </wa-dropdown-item>
+                              ${goToMenuItems(this.goToTarget, {
+                                  onSelect: () => {
+                                      this.selection.clear();
+                                      this.ctxMenu.close();
+                                  },
+                                  onHover: () =>
+                                      this.ctxMenu.closePlaylistSubmenu(),
+                              })}
                           </div>
                       `
                     : nothing}

frontend/src/components/selection-bar/selection-bar.ts

@@ -0,0 +1,218 @@
+import { LitElement, html, css, nothing } from 'lit';
+import { customElement, property } from 'lit/decorators.js';
+import '@awesome.me/webawesome/dist/components/icon/icon.js';
+import { designTokens } from '../../styles/tokens.css';
+import { ICON_MORE_ACTIONS } from '@utils/icon-language';
+
+/**
+ * What a selection can have done to it, while a finger is holding one.
+ *
+ * This is the context menu (plan 019, #63). Not a second surface
+ * beside it — the same actions, contextualised to whatever is
+ * selected, in the shape Android puts them in.
+ *
+ * #63 asked for a double tap to open the menu instead. That mapping
+ * costs the app's primary interaction 250ms on every play, because the
+ * first tap of a double tap is indistinguishable from a single tap
+ * until the interval expires, and playing a track is ~100ms end to end
+ * on the reference device. So there is no double tap: a long press
+ * selects, this says what can be done, and the sheet behind "More" is
+ * the same `menu-surface` every other menu in the app opens.
+ *
+ * Four things about it are load-bearing.
+ *
+ * **It is presentational.** It takes a count and a list of actions and
+ * emits `selection-action` / `selection-exit`; it holds no selection
+ * and calls no store. The host already owns a `SelectionController`
+ * and an action handler, and a bar that reached for either would be a
+ * second definition of what "play the selection" means — the fault
+ * `utils/library-status.ts` exists to have fixed one feature over.
+ *
+ * **The bar is only what fits, and "More" is the rest.** A context
+ * menu can be nine items because it is a sheet; a bar is one row on a
+ * 424px screen. So the host passes the two or three worth a thumb and
+ * the overflow opens the menu it already renders, which is what keeps
+ * every action reachable at every size — plan 018's promise, and the
+ * reason this cannot simply drop the long tail.
+ *
+ * **Its controls are 44px** (#56, #186), and the count is a live
+ * region: the number changes under the user's finger as they tap rows,
+ * and nothing else on screen announces it.
+ *
+ * **Escape leaves the mode, from here rather than from each host.**
+ * This element exists only while the mode does, so it is the one place
+ * a dismissal can be attached and detached with the thing it
+ * dismisses. It is the same exception the overlaid queue's Escape is.
+ *
+ * **It renders nothing at zero.** The mode ends when the last row is
+ * deselected — `SelectionController.toggleInMode` is where that is
+ * decided — so a bar with a count of none is a state this should never
+ * be asked to draw, and drawing it anyway would hide the fact that it
+ * has been.
+ */
+export interface SelectionAction {
+    id: string;
+    label: string;
+    icon: string;
+    danger?: boolean;
+}
+
+@customElement('selection-bar')
+export class SelectionBar extends LitElement {
+    static override styles = [
+        designTokens,
+        css`
+            :host {
+                display: block;
+            }
+
+            .bar {
+                display: flex;
+                align-items: center;
+                gap: 0.25em;
+                padding: 0.25em 0.5em;
+                background: var(--yj-bg-elevated, #343a40);
+                border-top: 1px solid var(--yj-border-subtle, #333);
+            }
+
+            .count {
+                flex: 1;
+                min-width: 0;
+                font-size: var(--yj-text-md);
+                font-weight: 600;
+                color: var(--yj-text-primary, #fff);
+                white-space: nowrap;
+                overflow: hidden;
+                text-overflow: ellipsis;
+            }
+
+            /* 44px, from #56 and #186 -- this is a bar a thumb uses. */
+            button {
+                display: flex;
+                align-items: center;
+                justify-content: center;
+                min-inline-size: 44px;
+                min-block-size: 44px;
+                padding: 0 0.5em;
+                border: none;
+                border-radius: 4px;
+                background: none;
+                color: var(--yj-text-primary, #fff);
+                font-family: inherit;
+                font-size: var(--yj-text-md);
+                cursor: pointer;
+            }
+
+            button:hover {
+                background: var(--yj-bg-overlay, #495057);
+            }
+
+            button.danger {
+                color: var(--yj-error-text, #ff8787);
+            }
+        `,
+    ];
+
+    /** How many items are selected. Zero renders nothing. */
+    @property({ type: Number }) count = 0;
+
+    /** The actions worth a thumb. The rest live behind "More". */
+    @property({ attribute: false }) actions: SelectionAction[] = [];
+
+    private emit(name: string, detail?: unknown) {
+        this.dispatchEvent(
+            new CustomEvent(name, { detail, bubbles: true, composed: true }),
+        );
+    }
+
+    /**
+     * Escape leaves the mode.
+     *
+     * A mode changes what a tap means, so it has to have an exit that
+     * is not "find the ×" -- and this is the documented exception to
+     * the app's one-keyboard-authority rule, on exactly the grounds
+     * the overlaid queue's Escape is: **it is a dismissal, not a
+     * shortcut**, so it is not a panel-scoped binding and it is
+     * attached only while there is something to dismiss. Putting it
+     * here rather than in each host is what gives all four surfaces
+     * the same answer, since this element exists only while the mode
+     * does.
+     *
+     * The platform's own back gesture is the other half of that and is
+     * deliberately *not* here: the shell owns the history stack
+     * (#6/#55), and a component reaching for `history` itself is how
+     * two stacks come to disagree about what one press means -- the
+     * fault that deleted `navStack`. See #200.
+     */
+    private onKeydown = (e: KeyboardEvent) => {
+        if (e.key !== 'Escape' || this.count <= 0) return;
+
+        e.preventDefault();
+        e.stopPropagation();
+        this.emit('selection-exit');
+    };
+
+    override connectedCallback() {
+        super.connectedCallback();
+        document.addEventListener('keydown', this.onKeydown, true);
+    }
+
+    override disconnectedCallback() {
+        super.disconnectedCallback();
+        document.removeEventListener('keydown', this.onKeydown, true);
+    }
+
+    override render() {
+        if (this.count <= 0) return nothing;
+
+        const noun = this.count === 1 ? 'track' : 'tracks';
+
+        return html`
+            <div class="bar" role="toolbar" aria-label="Selection actions">
+                <button
+                    aria-label="Leave selection"
+                    @click=${() => this.emit('selection-exit')}
+                >
+                    <wa-icon name="xmark"></wa-icon>
+                </button>
+                <span class="count" role="status" aria-live="polite">
+                    ${this.count.toLocaleString()} ${noun} selected
+                </span>
+                ${this.actions.map(
+                    (action) => html`
+                        <button
+                            class=${action.danger ? 'danger' : ''}
+                            aria-label=${action.label}
+                            title=${action.label}
+                            @click=${() =>
+                                this.emit('selection-action', { id: action.id })}
+                        >
+                            <wa-icon name=${action.icon}></wa-icon>
+                        </button>
+                    `,
+                )}
+                <button
+                    aria-label="More actions"
+                    @click=${(e: MouseEvent) => {
+                        const box = (
+                            e.currentTarget as HTMLElement
+                        ).getBoundingClientRect();
+
+                        this.emit('selection-more', {
+                            x: box.left,
+                            y: box.top,
+                        });
+                    }}
+                >
+                    <wa-icon name=${ICON_MORE_ACTIONS}></wa-icon>
+                </button>
+            </div>
+        `;
+    }
+}
+
+declare global {
+    interface HTMLElementTagNameMap {
+        'selection-bar': SelectionBar;
+    }
+}

frontend/src/components/sidebar/app-sidebar.ts

@@ -42,6 +42,26 @@ export class AppSidebar extends LitElement {
             scrollbar-width: thin;
         }
 
+        /* A host that has made room owns the box, not just the labels
+           (#71). The bottom-nav sheet is the width of the screen and
+           provides the one scroll container it needs; left to itself
+           the sidebar is a 200px column with a second scroller inside
+           it, which is what a nested scroll region feels like under a
+           thumb -- part of the surface moves and part of it does not. */
+        :host([expanded]) {
+            max-width: none;
+            height: auto;
+            overflow: visible;
+        }
+
+        /* And the width is not draggable there. It is a mouse
+           affordance (mousedown, col-resize) sitting on the right edge
+           of a touch surface, where the compatibility mouse events a
+           tap synthesises can start a resize nobody asked for. */
+        :host([expanded]) .resize-handle {
+            display: none;
+        }
+
         .resize-handle {
             position: absolute;
             top: 0;
@@ -95,8 +115,15 @@ export class AppSidebar extends LitElement {
             text-align: center;
         }
 
-        li button:hover {
+        /* A hover tint is for a device that hovers (#54), and this
-            background-color: var(--yj-bg-elevated, #343a40);
+           component is on a phone too: below 600px it is what
+           bottom-nav's "More" sheet mounts, where a hold
+           synthesises a hover and leaves a destination looking picked
+           after the finger has gone. */
+        @media (hover: hover) and (pointer: fine) {
+            li button:hover {
+                background-color: var(--yj-bg-elevated, #343a40);
+            }
         }
 
         li button:focus-visible {
@@ -108,6 +135,14 @@ export class AppSidebar extends LitElement {
             background-color: var(--yj-bg-overlay, #495057);
         }
 
+        /* The press state (#54), after the .active rule and at the same
+           specificity, so pressing the destination you are already on
+           still says something. It is what a tap gets now that
+           index.css has taken the web view's own highlight box away. */
+        li button:active {
+            background-color: var(--yj-press-overlay, rgba(255, 255, 255, 0.12));
+        }
+
         li button p {
             margin: 0;
             white-space: nowrap;
@@ -145,6 +180,25 @@ export class AppSidebar extends LitElement {
         :host(.collapsed) li button wa-icon {
             font-size: var(--yj-icon-md);
         }
+
+        /* Below 600px the only place this renders is the bottom-nav
+           sheet -- the shell's own copy is display: none there -- so
+           the rows are sized for the thumb that opened it: 48px, which
+           is #186's floor and the height every row in #60's context
+           sheet already has. A media query inside a shadow root is
+           answered by the viewport, so the component states this
+           itself rather than the sheet reaching in. */
+        @media (max-width: 599px) {
+            ul {
+                padding: 4px 8px 8px;
+            }
+
+            li button {
+                min-height: 48px;
+                padding: 12px 10px;
+                gap: 14px;
+            }
+        }
     `];
 
     /** Delay in ms before a drag-hover triggers navigation. */
@@ -173,11 +227,14 @@ export class AppSidebar extends LitElement {
 
     /**
      * Keep the labels regardless of the viewport, for a host that has
-     * made room for them -- `bottom-nav`'s drawer, which is the whole
+     * made room for them -- `bottom-nav`'s sheet, which is the whole
      * screen wide on the phone where this would otherwise auto-collapse
      * to icons. The auto-collapse is a *width* response to a narrow
-     * shell, and inside a drawer the shell is not what the sidebar is
+     * shell, and inside a sheet the shell is not what the sidebar is
      * sharing space with.
+     *
+     * It says the host owns the *box*, not only the labels: the width,
+     * the scrolling and the resize handle all follow it (#71).
      */
     @property({ type: Boolean, reflect: true })
     expanded = false;
@@ -350,9 +407,18 @@ export class AppSidebar extends LitElement {
      * be a media query in the stylesheet.
      */
     private applyViewportWidth() {
-        const narrow =
+        // A host that made room decides how much: `bottom-nav`'s sheet
-            !this.expanded &&
+        // is the whole screen wide, and the inline width below -- which
-            (this.narrowViewport?.matches ?? false);
+        // beats any rule the host could write -- would draw the old
+        // 200px side drawer inside it.
+        if (this.expanded) {
+            this.style.width = '100%';
+            this.collapsed = false;
+
+            return;
+        }
+
+        const narrow = this.narrowViewport?.matches ?? false;
         const width = narrow
             ? MIN_WIDTH
             : this.userWidth;

frontend/src/components/smart-playlist-details/smart-playlist-details.ts

@@ -28,6 +28,10 @@ import {
 } from '@utils/context-menu-controller.js';
 import type { ContextMenuHost, MenuTarget } from '@utils/context-menu-controller.js';
 import { focusRovingRow, nextRovingIndex } from '@utils/roving-rows';
+import type { GestureEvent } from '@utils/touch-gestures';
+import { SwipeToQueue, swipeRevealStyles } from '@utils/swipe-to-queue';
+import '@components/selection-bar/selection-bar';
+import type { SelectionAction } from '@components/selection-bar/selection-bar';
 import { FavoritesController } from '@store/controllers/favorites-controller';
 import {
     setDragPayload,
@@ -60,11 +64,16 @@ import {
     trackLink,
     exploreLinkStyles,
 } from '@utils/explore-link';
+import { goToMenuItems } from '@utils/go-to-menu';
+import type { GoToTarget } from '@utils/go-to-menu';
 import '@components/smart-playlist-editor/smart-playlist-editor.js';
 import { designTokens } from '../../styles/tokens.css';
 import { backButton } from '../../styles/back-button.css';
+import { srOnly } from '../../styles/sr-only.css';
 import { list } from '@utils/binding';
 import {
+    ICON_PLAY,
+    ICON_PLAY_NEXT,
     ICON_PLAYLIST,
     ICON_QUEUE,
     ICON_SMART_PLAYLIST,
@@ -243,9 +252,11 @@ export class SmartPlaylistDetails
 
     static override styles = [
         designTokens,
+        srOnly,
         backButton,
         contextMenuStyles,
         exploreLinkStyles,
+        swipeRevealStyles,
         css`
         :host {
             display: flex;
@@ -444,6 +455,9 @@ export class SmartPlaylistDetails
         .track-item {
             width: 100%;
             box-sizing: border-box;
+            /* The swipe reveal is absolute inside the row. */
+            position: relative;
+            overflow: hidden;
         }
 
         .track-header {
@@ -502,8 +516,14 @@ export class SmartPlaylistDetails
             user-select: none;
         }
 
-        .track-item:hover {
+        /* A hover tint is for a device that hovers (#54). A hold
-            background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+           synthesises a hover in the WebView, so ungated this arrives
+           because a finger touched the row and stays after it has
+           gone; the press state below is what a tap gets instead. */
+        @media (hover: hover) and (pointer: fine) {
+            .track-item:hover {
+                background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+            }
         }
 
         .track-item.selected {
@@ -519,6 +539,19 @@ export class SmartPlaylistDetails
             background-color: var(--yj-selection-bg, rgba(100, 160, 255, 0.15));
         }
 
+        /* The press state (#54): the feedback a tap has now that the
+           web view's own highlight box is gone (index.css). Last, and
+           carrying a class, because a selected or playing row is two
+           classes deep and a bare :active would lose to it. */
+        .track-item.selected:active,
+        .track-item.active:active,
+        .track-item:active {
+            background-color: var(
+                --yj-press-overlay,
+                rgba(255, 255, 255, 0.12)
+            );
+        }
+
         /* Phantom rows span the full grid */
         .track-item.phantom {
             display: grid;
@@ -916,10 +949,136 @@ export class SmartPlaylistDetails
             .map((i) => this.tracks[i]!.FilePath);
     }
 
+    /**
+     * The row "Go to Artist" / "Go to Album" navigate from — one row
+     * or none, and only below the phone breakpoint, where the row's
+     * own names stopped being links (#67).
+     */
+    private get goToTarget(): GoToTarget | undefined {
+        const indices = this.selection.getSelectedIndices();
+
+        if (indices.length !== 1) return undefined;
+
+        const track = this.tracks[indices[0]!];
+
+        if (!track) return undefined;
+
+        return {
+            artistName: track.Artist,
+            artistMBID: track.ArtistMBID,
+            albumName: track.Album,
+            albumMBID: track.ReleaseGroupMBID,
+        };
+    }
+
     // =================================================================
     // Context menu actions
     // =================================================================
 
+    // =================================================================
+    // A finger on a smart playlist row (plan 019 phase 3, #63)
+    // =================================================================
+
+    /** The row an announced gesture is on, with its track. */
+    private rowFromGesture(
+        e: Event,
+    ): { index: number; track: playlist.Track } | null {
+        const row = (e.target as HTMLElement).closest(
+            '.track-item',
+        ) as HTMLElement | null;
+
+        if (!row) return null;
+
+        const index = Number(row.dataset.index);
+        const track = this.tracks[index];
+
+        if (Number.isNaN(index) || !track) return null;
+
+        return { index, track };
+    }
+
+    /** A tap plays the playlist from that row -- `playlist-details`'
+     *  rule, and the app's: activating a row plays the list it is in. */
+    private onRowTap = (e: GestureEvent) => {
+        const hit = this.rowFromGesture(e);
+
+        if (!hit) return;
+
+        if (this.selection.selectionMode) {
+            e.preventDefault();
+            this.focusedIndex = hit.index;
+            this.selection.toggleInMode(String(hit.index), hit.index);
+            this.virtualizer?.requestUpdate();
+
+            return;
+        }
+
+        // A missing file has nothing to play, so the tap falls through
+        // to the click that selects it.
+        if (hit.track.Phantom) return;
+
+        e.preventDefault();
+        this.focusedIndex = hit.index;
+        this.handleTrackDblClick(hit.index);
+    };
+
+    private onRowLongPress = (e: GestureEvent) => {
+        const hit = this.rowFromGesture(e);
+
+        if (!hit) return;
+
+        e.preventDefault();
+        this.focusedIndex = hit.index;
+        this.selection.enterSelectionMode(String(hit.index), hit.index);
+        this.virtualizer?.requestUpdate();
+    };
+
+    private swipe = new SwipeToQueue(this, {
+        resolve: (e) => {
+            const hit = this.rowFromGesture(e);
+
+            if (!hit || hit.track.Phantom) return null;
+
+            const selected = this.selection.getSelectedIndices();
+            const many =
+                selected.length > 1 && selected.includes(hit.index);
+            const filePaths = many
+                ? this.getSelectedFilePaths()
+                : [hit.track.FilePath];
+
+            return { index: hit.index, filePaths, label: hit.track.Title };
+        },
+        repaint: () => this.virtualizer?.requestUpdate(),
+    });
+
+    /** The three worth a thumb; the sheet behind "More" is the rest. */
+    private static readonly SELECTION_ACTIONS: SelectionAction[] = [
+        { id: 'play', label: 'Play', icon: ICON_PLAY },
+        { id: 'add-to-queue', label: 'Add to queue', icon: ICON_QUEUE },
+        { id: 'play-next', label: 'Play next', icon: ICON_PLAY_NEXT },
+    ];
+
+    private renderSelectionBar() {
+        if (!this.selection.selectionMode) return nothing;
+
+        return html`
+            <selection-bar
+                .count=${this.selection.selectionCount}
+                .actions=${SmartPlaylistDetails.SELECTION_ACTIONS}
+                @selection-exit=${this.onSelectionExit}
+                @selection-action=${(e: CustomEvent<{ id: string }>) =>
+                this.onContextMenuAction(e.detail.id)}
+                @selection-more=${(e: CustomEvent<{ x: number; y: number }>) =>
+                this.ctxMenu.openAt(e.detail.x, e.detail.y)}
+            ></selection-bar>
+        `;
+    }
+
+    private onSelectionExit = () => {
+        this.selection.exitSelectionMode();
+        this.virtualizer?.requestUpdate();
+    };
+
     private onContextMenuAction(action: string) {
         const filePaths = this.getSelectedFilePaths();
 
@@ -1334,6 +1493,9 @@ export class SmartPlaylistDetails
                 <div class="header-cell col-album">Album</div>
                 <div class="header-cell col-duration">Duration</div>
             </div>
+            <div class="sr-only" role="status" aria-live="polite">
+                ${this.swipe.announcement}
+            </div>
             <lit-virtualizer
                 role="listbox"
                 aria-label="Smart playlist tracks"
@@ -1342,7 +1504,13 @@ export class SmartPlaylistDetails
                 .renderItem=${this.renderRow}
                 .keyFunction=${this.rowKey}
                 .layout=${this.flowLayout}
+                @yj-tap=${this.onRowTap}
+                @yj-long-press=${this.onRowLongPress}
+                @yj-swipe-start=${this.swipe.onSwipeStart}
+                @yj-swipe-move=${this.swipe.onSwipeMove}
+                @yj-swipe-end=${this.swipe.onSwipeEnd}
             ></lit-virtualizer>
+            ${this.renderSelectionBar()}
         `;
     }
 
@@ -1364,6 +1532,7 @@ export class SmartPlaylistDetails
                         active ? 'active' : '',
                         selected ? 'selected' : '',
                         isPhantom ? 'phantom' : '',
+                        this.swipe.isSwiping(trackIndex) ? 'swiping' : '',
                     ]
                         .filter(Boolean)
                         .join(' ');
@@ -1374,6 +1543,7 @@ export class SmartPlaylistDetails
                             role="option"
                             aria-selected=${selected}
                             data-index=${trackIndex}
+                            data-swipe
                             tabindex=${trackIndex === this.focusedIndex ? 0 : -1}
                             @keydown=${(e: KeyboardEvent) =>
                                 this.onRowKeydown(e, trackIndex)}
@@ -1408,6 +1578,7 @@ export class SmartPlaylistDetails
                                 ? nothing
                                 : this.onTrackDragEnd}
                         >
+                            ${this.swipe.renderReveal(trackIndex)}
                             ${isPhantom
                                 ? html`<div class="phantom-row">
                                       <wa-icon
@@ -1555,6 +1726,14 @@ export class SmartPlaylistDetails
                                   ></wa-icon>
                                   Track Details
                               </wa-dropdown-item>
+                              ${goToMenuItems(this.goToTarget, {
+                                  onSelect: () => {
+                                      this.selection.clear();
+                                      this.ctxMenu.close();
+                                  },
+                                  onHover: () =>
+                                      this.ctxMenu.closePlaylistSubmenu(),
+                              })}
                           </div>
                       `
                     : nothing}

frontend/src/components/top-results-row/top-results-row.ts

@@ -371,8 +371,11 @@ export class TopResultsRow extends LitElement {
                         <span class="card-name">${r.name}</span>
                         ${artistPart || metaPart
                             ? html`<span class="card-subtitle"
-                                  >${artistPart
+                                  ><!-- keepOnPhone: this card has no
-                                      ? creditLink(creditStore.credits(r.mbid), artistPart, r.artistMbid ?? '')
+                                       context menu, so the credit is
+                                       the only route to the artist of
+                                       a top result (#67). -->${artistPart
+                                      ? creditLink(creditStore.credits(r.mbid), artistPart, r.artistMbid ?? '', { keepOnPhone: true })
                                       : nothing}${artistPart && metaPart
                                       ? ' · '
                                       : ''}${metaPart}</span

frontend/src/components/track-list/track-list.ts

@@ -10,6 +10,10 @@ import {
 } from 'lit/decorators.js';
 import { SelectionController } from '@utils/selection-controller';
 import type { SelectionHost } from '@utils/selection-controller';
+import type { GestureEvent } from '@utils/touch-gestures';
+import { SwipeToQueue, swipeRevealStyles } from '@utils/swipe-to-queue';
+import '@components/selection-bar/selection-bar';
+import type { SelectionAction } from '@components/selection-bar/selection-bar';
 import { ViewLifecycleMixin } from '@utils/view-lifecycle';
 import { PHONE_QUERY } from '@utils/breakpoints';
 import {
@@ -47,6 +51,8 @@ import {
     trackLink,
     exploreLinkStyles,
 } from '@utils/explore-link';
+import { goToMenuItems } from '@utils/go-to-menu';
+import type { GoToTarget } from '@utils/go-to-menu';
 import {
     setDragPayload,
     emitDragActive,
@@ -77,7 +83,9 @@ import '@components/playlist-picker/playlist-picker.js';
 import type { TrackDetails } from '@components/track-details/track-details.js';
 import type { CoverArtUrls } from '@components/track-details/track-details.js';
 import {
+    ICON_PLAY,
     ICON_PLAYLIST,
+    ICON_PLAY_NEXT,
     ICON_QUEUE,
 } from '@utils/icon-language';
 
@@ -277,6 +285,29 @@ export class TrackList
      *  path into it at all (H-5). */
     @state() private focusedIndex = 0;
 
+    /**
+     * Swipe a row right to queue it (plan 019 phase 2, #63).
+     *
+     * The affordance and the arithmetic are `utils/swipe-to-queue.ts`,
+     * shared with both playlist detail views; what stays here is what
+     * only this list knows -- which row an event is on, and what a
+     * swipe on it means when other rows are selected.
+     */
+    private swipe = new SwipeToQueue(this, {
+        resolve: (e) => {
+            const hit = this.resolveTrackFromEvent(e);
+
+            if (!hit) return null;
+
+            return {
+                index: hit.index,
+                filePaths: this.swipeTargetKeys(hit.track.FilePath),
+                label: hit.track.TrackName,
+            };
+        },
+        repaint: () => this.virtualizer?.requestUpdate(),
+    });
+
     private handleSelectAll = (): void => {
         this.selection.selectAll();
     };
@@ -1011,7 +1042,7 @@ export class TrackList
         this.requestUpdate();
     };
 
-    static override styles = [designTokens, srOnly, contextMenuStyles, exploreLinkStyles, css`
+    static override styles = [designTokens, srOnly, contextMenuStyles, exploreLinkStyles, swipeRevealStyles, css`
     :host {
       display: flex;
       flex-direction: column;
@@ -1170,8 +1201,16 @@ export class TrackList
       padding-left: 6px;
     }
 
-    .track-row:hover {
+    /* A hover tint is for a device that hovers (#54): a hold
-      background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+       synthesises a hover in the WebView, so ungated this is a
+       highlight that arrives because a finger touched the row and
+       then stays there after it has gone -- which reads as a
+       selection the user did not make. Same gate, and the same
+       mechanism, as #68's revealed controls. */
+    @media (hover: hover) and (pointer: fine) {
+      .track-row:hover {
+        background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+      }
     }
 
     .track-row.selected {
@@ -1208,6 +1247,24 @@ export class TrackList
       background-color: var(--yj-selection-bg, rgba(100, 160, 255, 0.15));
     }
 
+    /* The press state (#54), and the only feedback a tap has now that
+       the web view's tap highlight is gone (index.css).
+
+       **Last, and as specific as the state rules above**: a row that
+       is selected and playing is .track-row.selected.active, so a
+       bare .track-row:active is one class short of it and a press
+       on the row a phone is most likely to press -- the one it just
+       selected -- would show nothing. Instant rather than
+       transitioned, because the only measured statement here about
+       transitions on a list is that two card grids removed theirs
+       for software-rendering repaint cost. */
+    .track-row.selected:active,
+    .track-row.active:active,
+    .track-row:active {
+      background-color: var(--yj-press-overlay, rgba(255, 255, 255, 0.12));
+    }
+
+
     .cell {
       overflow: hidden;
       text-overflow: ellipsis;
@@ -1304,6 +1361,11 @@ export class TrackList
             virt.removeEventListener('click', this.onDelegatedClick);
             virt.removeEventListener('dblclick', this.onDelegatedDblClick);
             virt.removeEventListener('contextmenu', this.onDelegatedContextMenu);
+            virt.removeEventListener('yj-tap', this.onRowTap);
+            virt.removeEventListener('yj-long-press', this.onRowLongPress);
+            virt.removeEventListener('yj-swipe-start', this.swipe.onSwipeStart);
+            virt.removeEventListener('yj-swipe-move', this.swipe.onSwipeMove);
+            virt.removeEventListener('yj-swipe-end', this.swipe.onSwipeEnd);
             virt.removeEventListener('dragstart', this.onDelegatedDragStart);
             virt.removeEventListener('dragend', this.onTrackDragEnd);
         }
@@ -1445,6 +1507,14 @@ export class TrackList
         virt.addEventListener('contextmenu', this.onDelegatedContextMenu);
         virt.addEventListener('dragstart', this.onDelegatedDragStart);
         virt.addEventListener('dragend', this.onTrackDragEnd);
+        // Delegated like the rest: the gesture layer dispatches on the
+        // element the finger landed on, composed, so it arrives here
+        // through the same path a real click takes (plan 019).
+        virt.addEventListener('yj-tap', this.onRowTap);
+        virt.addEventListener('yj-long-press', this.onRowLongPress);
+        virt.addEventListener('yj-swipe-start', this.swipe.onSwipeStart);
+        virt.addEventListener('yj-swipe-move', this.swipe.onSwipeMove);
+        virt.addEventListener('yj-swipe-end', this.swipe.onSwipeEnd);
         this.delegationAttached = true;
     }
 
@@ -1708,6 +1778,86 @@ export class TrackList
         if (hit) this.onTrackContextMenu(e, hit.track);
     };
 
+    /**
+     * A finger tapped a row (plan 019, #63).
+     *
+     * On a desktop a click selects and a double-click plays; a finger
+     * inverts that, because there is no second button and no modifier
+     * key, so the primary action has to be the primary gesture.
+     *
+     * Claiming the gesture (`preventDefault`) is what tells the layer
+     * to swallow the click behind it -- otherwise playing a track
+     * would also select it, and the row would end up in both states.
+     * A tap this does *not* claim falls through as an ordinary click,
+     * which is what keeps the favourite icon working.
+     */
+    private onRowTap = (e: GestureEvent) => {
+        const hit = this.resolveTrackFromEvent(e);
+
+        if (!hit) return;
+
+        // A control inside the row owns its own tap. The same rule the
+        // shortcut service has for a focused control that owns a key,
+        // and without it the 44px favourite target (#56) becomes a
+        // 44px play target.
+        if ((e.target as HTMLElement).closest('.fav-icon')) return;
+
+        e.preventDefault();
+        this.focusedIndex = hit.index;
+
+        if (this.selection.selectionMode) {
+            this.selection.toggleInMode(hit.track.FilePath, hit.index);
+            this.virtualizer?.requestUpdate();
+
+            return;
+        }
+
+        this.playFromRow(hit.index);
+    };
+
+    /**
+     * A finger held a row still for half a second.
+     *
+     * Claiming this is what makes it *selection mode* rather than the
+     * context menu it has been since plan 016 -- an unclaimed
+     * `yj-long-press` still becomes a `contextmenu`, which is how the
+     * card grids and Explore keep the behaviour they have.
+     */
+    private onRowLongPress = (e: GestureEvent) => {
+        const hit = this.resolveTrackFromEvent(e);
+
+        if (!hit) return;
+
+        e.preventDefault();
+        this.focusedIndex = hit.index;
+        this.selection.enterSelectionMode(hit.track.FilePath, hit.index);
+        this.virtualizer?.requestUpdate();
+    };
+
+    /**
+     * What a swipe on this row would queue.
+     *
+     * The same rule the context menu answers with, and it has to be:
+     * **one row is a position, several rows are an explicit choice.**
+     * A finger that swipes a row which is part of a selection of forty
+     * has not un-made that selection, and queueing the one row it
+     * touched would quietly contradict the bar above saying forty are
+     * selected. A swipe on a row *outside* the selection is a statement
+     * about that row, exactly as a right-click on one is -- and unlike
+     * a right-click it does not move the selection, because a swipe is
+     * not a way of selecting anything.
+     */
+    private swipeTargetKeys(filePath: string): string[] {
+        if (
+            this.selection.selectionCount > 1 &&
+            this.selection.isSelected(filePath)
+        ) {
+            return this.selection.getSelectedKeysOrdered();
+        }
+
+        return [filePath];
+    }
+
     private onDelegatedDragStart = (e: DragEvent) => {
         const hit = this.resolveTrackFromEvent(e);
 
@@ -1831,6 +1981,33 @@ export class TrackList
         emitDragActive(false);
     };
 
+    /**
+     * The row the menu can navigate from, for "Go to Artist" / "Go to
+     * Album" — which exist only below the phone breakpoint, where the
+     * row's own names are no longer links (#67).
+     *
+     * One row only, on the rule the Play item already states: one row
+     * is a position, several are an explicit choice of *those* tracks,
+     * and "go to the album" of five different albums means nothing.
+     */
+    private get goToTarget(): GoToTarget | undefined {
+        if (this.selection.selectionCount !== 1) return undefined;
+
+        const [path] = this.selection.selectedItems;
+        const track = path
+            ? tracksByFilePath(this.tracks).get(path)
+            : undefined;
+
+        if (!track) return undefined;
+
+        return {
+            artistName: track.ArtistName,
+            artistMBID: track.ArtistMBID,
+            albumName: track.Album,
+            albumMBID: track.ReleaseGroupMBID,
+        };
+    }
+
     private onContextMenuAction(action: string) {
         const filePaths =
             this.selection.getSelectedKeysOrdered();
@@ -2129,6 +2306,7 @@ export class TrackList
             'track-row': true,
             active,
             selected,
+            swiping: this.swipe.isSwiping(index),
         })}
         role="row"
         aria-rowindex=${index + 1}
@@ -2138,8 +2316,10 @@ export class TrackList
         draggable="true"
         data-index=${index}
         data-testid="track-row"
+        data-swipe
         data-file-path=${track.FilePath}
       >
+        ${this.swipe.renderReveal(index)}
         <div
           role="gridcell"
           class=${classMap({
@@ -2238,6 +2418,45 @@ export class TrackList
         this.saveSortPreferences();
     };
 
+    /**
+     * The three worth a thumb. Everything else is behind "More",
+     * which opens the context menu this list already renders.
+     *
+     * A bar is one row on a 424px screen and the menu is nine items,
+     * so this is a subset by necessity rather than a second opinion
+     * about what matters -- and plan 018's promise that no action is
+     * unreachable is kept by the overflow, not by this list.
+     */
+    private static readonly SELECTION_ACTIONS: SelectionAction[] = [
+        { id: 'play', label: 'Play', icon: ICON_PLAY },
+        { id: 'add-to-queue', label: 'Add to queue', icon: ICON_QUEUE },
+        { id: 'play-next', label: 'Play next', icon: ICON_PLAY_NEXT },
+    ];
+
+    private renderSelectionBar() {
+        // Only in selection mode: a mouse selection is modeless and
+        // shows its actions on right-click, which is where a desktop
+        // user looks for them.
+        if (!this.selection.selectionMode) return nothing;
+
+        return html`
+            <selection-bar
+                .count=${this.selection.selectionCount}
+                .actions=${TrackList.SELECTION_ACTIONS}
+                @selection-exit=${this.onSelectionExit}
+                @selection-action=${(e: CustomEvent<{ id: string }>) =>
+                    this.onContextMenuAction(e.detail.id)}
+                @selection-more=${(e: CustomEvent<{ x: number; y: number }>) =>
+                    this.ctxMenu.openAt(e.detail.x, e.detail.y)}
+            ></selection-bar>
+        `;
+    }
+
+    private onSelectionExit = () => {
+        this.selection.exitSelectionMode();
+        this.virtualizer?.requestUpdate();
+    };
+
     override render() {
         const visibleTracks = this.cachedSortedTracks;
         const cols = this.activeColumns;
@@ -2247,6 +2466,9 @@ export class TrackList
       <div class="sr-only" role="status" aria-live="polite">
         ${this.liveStatus(visibleTracks.length)}
       </div>
+      <div class="sr-only" role="status" aria-live="polite">
+        ${this.swipe.announcement}
+      </div>
       ${this.tracks.length === 0
                 ? this.renderPlaceholder()
                 : html`
@@ -2322,6 +2544,7 @@ export class TrackList
                     )}
       </div>
             </div>
+            ${this.renderSelectionBar()}
           `}
 
       <menu-surface
@@ -2394,6 +2617,13 @@ export class TrackList
                     ></wa-icon>
                     Track Details
                 </wa-dropdown-item>
+                ${goToMenuItems(this.goToTarget, {
+                    onSelect: () => {
+                        this.selection.clear();
+                        this.ctxMenu.close();
+                    },
+                    onHover: () => this.ctxMenu.closePlaylistSubmenu(),
+                })}
                 <wa-dropdown-item
                     @click=${() =>
                         this.onContextMenuAction(

frontend/src/store/theme-store.ts

@@ -46,6 +46,17 @@ export interface ShadePalette {
     border: string;
     borderSubtle: string;
     hoverOverlay: string;
+    /**
+     * The tint a surface takes while it is being pressed (#54).
+     *
+     * Separate from `hoverOverlay` because the two answer different
+     * questions and only one of them a phone can ask: a hover is a
+     * pointer resting somewhere, a press is a finger on the thing it
+     * is about to activate. It is deliberately the stronger of the
+     * two — a press that reads the same as a hover says nothing on a
+     * device where the hover is synthesised by the press itself.
+     */
+    pressOverlay: string;
     selectionBg: string;
 }
 
@@ -95,6 +106,7 @@ export const SHADE_PALETTES: Record<BackgroundShade, ShadePalette> = {
         border: '#333333',
         borderSubtle: '#222222',
         hoverOverlay: 'rgba(255, 255, 255, 0.05)',
+        pressOverlay: 'rgba(255, 255, 255, 0.12)',
         selectionBg: 'rgba(100, 160, 255, 0.15)',
     },
     dark: {
@@ -114,6 +126,7 @@ export const SHADE_PALETTES: Record<BackgroundShade, ShadePalette> = {
         border: '#444444',
         borderSubtle: '#333333',
         hoverOverlay: 'rgba(255, 255, 255, 0.05)',
+        pressOverlay: 'rgba(255, 255, 255, 0.12)',
         selectionBg: 'rgba(100, 160, 255, 0.15)',
     },
     light: {
@@ -133,6 +146,7 @@ export const SHADE_PALETTES: Record<BackgroundShade, ShadePalette> = {
         border: '#ced4da',
         borderSubtle: '#dee2e6',
         hoverOverlay: 'rgba(0, 0, 0, 0.05)',
+        pressOverlay: 'rgba(0, 0, 0, 0.12)',
         selectionBg: 'rgba(100, 160, 255, 0.15)',
     },
 };
@@ -285,6 +299,7 @@ function deriveThemeVariables(
 
         // Interactive overlays
         '--yj-hover-overlay': palette.hoverOverlay,
+        '--yj-press-overlay': palette.pressOverlay,
         '--yj-selection-bg': palette.selectionBg,
 
         // Semantic *fills* — the background of a solid button or badge.

frontend/src/styles/sheet-scroll.css.ts

@@ -0,0 +1,68 @@
+import { css } from 'lit';
+
+/**
+ * A bottom sheet whose body scrolls says so, in one rule both sheets
+ * read.
+ *
+ * The app has two sheets — `menu-surface`'s context menu (#60) and
+ * `bottom-nav`'s "More" navigation (#71) — and both are capped at 85vh,
+ * because a surface covering the whole screen is a page rather than a
+ * sheet. So both overflow, and both used to overflow *silently*: the
+ * menu at 424x439 with eight items ending at y=470 (#207), the nav
+ * sheet at the same viewport with `scrollHeight` 412 against
+ * `clientHeight` 373 (#210). Where the cut lands on a row boundary the
+ * sheet ends in a clean edge that reads as the end of the list.
+ *
+ * The mechanism is #207's and is unchanged by being shared: two
+ * background layers on the scrolling box, whose *attachments* are the
+ * conditionality. A cover of the sheet's own colour is painted at the
+ * end of the *content* (`local`) over a shadow pinned to the box
+ * (`scroll`), so the cover scrolls up over the shadow exactly when
+ * there is nothing more to see. The fade is therefore absent on a sheet
+ * that fits, present the moment one does not, and gone again at the end
+ * of the list — with no scroll listener, no measurement and nothing
+ * reaching into another component's shadow root for the scroller.
+ * `background-attachment` is Chrome 4; the reference device is
+ * Chrome 113.
+ *
+ * Three things about it are load-bearing.
+ *
+ * **The cover takes the sheet's own colour, from a custom property.**
+ * The two sheets are different greys — the nav sheet paints
+ * `--yj-bg-surface`, because it holds the sidebar and two greys in one
+ * sheet is a seam across the middle of it, while the context sheet
+ * paints the menus' `--yj-bg-elevated`. A shared rule that hard-coded
+ * either would put that seam back on the other one, so the host sets
+ * `--yj-sheet-surface` on the same box and this reads it.
+ *
+ * **The curve is steep because the rows under it stay live.** A scrim
+ * over a menu item is that item's text surface, and this app's rule is
+ * that text clears 4.5:1 on every surface it can sit on — which the
+ * light ramp, whose `bgElevated` is `#e9ecef`, makes non-theoretical. A
+ * row is 48px with its label centred, so 32px of scrim already down to
+ * a quarter strength at 14px spends its weight on the strip below the
+ * last legible label: measured at 9.9:1 on that label on the light ramp,
+ * against 5.0:1 for a linear 48px draft at 0.8. The dark-ramp pixel
+ * table is in `.planning/NOTES.md` (2026-08-23).
+ *
+ * **The box is declared a scroller here too.** `overflow-y: auto` is
+ * part of the same statement rather than left to each host: a fade over
+ * a box that is not the scroller is a fade that never moves, and the
+ * component tier asserts the pair together for that reason.
+ */
+export const sheetScrollFade = css`
+    overflow-y: auto;
+    background:
+        linear-gradient(
+                var(--yj-sheet-surface, #343a40),
+                var(--yj-sheet-surface, #343a40)
+            )
+            bottom / 100% 32px no-repeat local,
+        linear-gradient(
+                to top,
+                rgba(0, 0, 0, 0.6) 0%,
+                rgba(0, 0, 0, 0.25) 45%,
+                rgba(0, 0, 0, 0) 100%
+            )
+            bottom / 100% 32px no-repeat scroll;
+`;

frontend/src/utils/context-menu-controller.ts

@@ -710,10 +710,35 @@ export const contextMenuStyles = css`
         font-size: 13px;
     }
 
-    .context-menu-panel wa-dropdown-item:hover {
+    /* A hover tint is for a device that hovers (#54).
+
+       Below the query is a phone, where a hold *synthesises* a hover
+       in the WebView -- the same mechanism #68 gates the revealed
+       controls on -- so an ungated tint is a highlight that arrives
+       because a finger touched the row and then stays on it after the
+       finger has gone. Which is indistinguishable from the press
+       state below, and outlives it. */
+    @media (hover: hover) and (pointer: fine) {
+        .context-menu-panel wa-dropdown-item:hover {
+            background-color: var(
+                --yj-hover-overlay,
+                rgba(255, 255, 255, 0.1)
+            );
+        }
+    }
+
+    /* And a press state is for every device, because it is the one
+       piece of feedback a tap has now that the web view's own
+       highlight box is gone (index.css). Stronger than the hover tint
+       on purpose, and instant rather than transitioned: the only
+       measured statement this repo has about transitions on these
+       surfaces is the two card grids that removed theirs because
+       software rendering repaints per frame, and the phone is not
+       something this session can measure. */
+    .context-menu-panel wa-dropdown-item:active {
         background-color: var(
-            --yj-hover-overlay,
+            --yj-press-overlay,
-            rgba(255, 255, 255, 0.1)
+            rgba(255, 255, 255, 0.12)
         );
     }
 

frontend/src/utils/explore-link.ts

@@ -13,11 +13,35 @@
  * bug, not as a statement about metadata.  The only case that still
  * renders as text is one we genuinely cannot route (no name at all, or
  * nothing in the library by that name).
+ *
+ * ## Below the phone breakpoint a name is not a link (#67)
+ *
+ * A few characters of text inside a row is not a touch target, and the
+ * click handling below is explicitly a *desktop* compromise: the
+ * navigation is held for one double-click interval so double-clicking
+ * the row can still play it, which means nothing at all on touch.  On
+ * a phone the row's own gesture wins anyway — a claimed `yj-tap` has
+ * its click swallowed by `utils/touch-gestures.ts`, so the link was
+ * unreachable as well as fiddly.
+ *
+ * So the rule lives here rather than at twenty call sites, which is
+ * what the Findings on #67 ask for: a name renders as plain text below
+ * `PHONE_QUERY`, and the row's context menu carries "Go to Artist" /
+ * "Go to Album" in its place (`goToMenuItems`).
+ *
+ * The exception is `keepOnPhone`, and it is not a preference.  Three
+ * surfaces render a name with **no menu to carry the destination** —
+ * `now-playing-view`, `explore-album-details`' header credit and
+ * `top-results-row` — so suppressing the link there takes the action
+ * away entirely rather than moving it, which is what plan 018's "no
+ * action is unreachable at any supported size" refuses.  Each of those
+ * call sites says so.
  */
 
 import { html, css } from 'lit';
 import type { TemplateResult } from 'lit';
 import { libraryStore } from '../store/library-store';
+import { PHONE_QUERY } from './breakpoints';
 
 /** Shared CSS for explore link styling. Import into component styles. */
 export const exploreLinkStyles = css`
@@ -32,6 +56,57 @@ export const exploreLinkStyles = css`
     }
 `;
 
+/**
+ * Options every link function takes, for the one case that is not the
+ * default.
+ */
+export interface LinkOptions {
+    /**
+     * Keep the name navigable at phone width.
+     *
+     * For a surface with no context menu to carry the destination —
+     * see the header of this file.  A row must not pass it: the row's
+     * tap already means "play", and the menu is where the destination
+     * went.
+     */
+    keepOnPhone?: boolean;
+}
+
+/**
+ * The live phone breakpoint, made once and read per link.
+ *
+ * A `MediaQueryList` is live, so one object answers for the life of
+ * the page and a resize needs nothing from here.  The identity check
+ * is the test seam: this tier's viewport is fixed by the runner, so a
+ * spec answers the query by replacing `window.matchMedia` (the same
+ * stub `now-playing-phone.test.ts` installs), and swapping the
+ * function is what tells us to ask again.
+ */
+let phoneQuery: MediaQueryList | undefined;
+let phoneQuerySource: typeof window.matchMedia | undefined;
+
+/**
+ * Whether an inline name still navigates.
+ *
+ * Exported because the menus that carry the destination in its place
+ * are drawn under exactly the same condition -- one answer, not two.
+ */
+export function inlineLinksSuppressed(): boolean {
+    if (!window.matchMedia) return false;
+
+    if (phoneQuerySource !== window.matchMedia) {
+        phoneQuerySource = window.matchMedia;
+        phoneQuery = window.matchMedia(PHONE_QUERY);
+    }
+
+    return phoneQuery?.matches ?? false;
+}
+
+/** Whether this call site should render plain text rather than a link. */
+function plainText(options?: LinkOptions): boolean {
+    return !options?.keepOnPhone && inlineLinksSuppressed();
+}
+
 /** Fire a navigate event from the clicked element. */
 function navigate(target: EventTarget, detail: Record<string, unknown>): void {
     target.dispatchEvent(
@@ -153,39 +228,19 @@ function singleClick(
  * @param mbid - The MusicBrainz artist ID.  Empty string = local only.
  * @param content - Optional custom content to render inside the link
  *                  (e.g. highlighted search result).  Defaults to artistName.
+ * @param options - See `LinkOptions`.
  */
 export function artistLink(
     artistName: string,
     mbid: string,
     content?: TemplateResult | string,
+    options?: LinkOptions,
 ): TemplateResult | string {
     if (!artistName) return artistName;
+    if (plainText(options)) return content ?? artistName;
 
     const onClick = singleClick((target) => {
-        void (async () => {
+        void openArtistPage(target, artistName, mbid);
-            if (mbid) {
-                navigate(target, {
-                    view: 'explore-artist-details',
-                    artistMBID: mbid,
-                    artistName,
-                });
-
-                return;
-            }
-
-            const local = await findLocalArtist(artistName);
-            if (!local) return;
-
-            // The caller's row had no MBID, but the library row for the
-            // same artist may — the grid routes by exactly this field,
-            // so reading it here is what keeps the two paths agreeing.
-            navigate(target, {
-                view: 'explore-artist-details',
-                artistMBID: local.MBID || '',
-                artistName,
-                localArtistId: local.ID,
-            });
-        })();
     });
 
     return html`<a
@@ -203,19 +258,22 @@ export function artistLink(
  * @param mbid - The MusicBrainz release group ID.  Empty = local only.
  * @param content - Optional custom content to render inside the link.
  * @param artistName - Disambiguates same-named albums in the library.
+ * @param options - See `LinkOptions`.
  */
 export function albumLink(
     albumName: string,
     mbid: string,
     content?: TemplateResult | string,
     artistName?: string,
+    options?: LinkOptions,
 ): TemplateResult | string {
     if (!albumName) return albumName;
+    if (plainText(options)) return content ?? albumName;
 
     return html`<a
         class="explore-link"
         @click=${singleClick((target) => {
-            void openAlbum(target, albumName, mbid, artistName);
+            void openAlbumPage(target, albumName, mbid, artistName);
         })}
         title=${mbid ? 'View album on Explore' : 'View album in your library'}
     >${content ?? albumName}</a>`;
@@ -232,6 +290,7 @@ export function albumLink(
  * @param recordingMBID - The track's MusicBrainz recording ID.
  * @param content - Optional custom content (e.g. highlighted text).
  * @param artistName - Disambiguates same-named albums in the library.
+ * @param options - See `LinkOptions`.
  */
 export function trackLink(
     trackName: string,
@@ -240,14 +299,16 @@ export function trackLink(
     recordingMBID: string,
     content?: TemplateResult | string,
     artistName?: string,
+    options?: LinkOptions,
 ): TemplateResult | string {
     if (!trackName) return trackName;
     if (!albumName) return content ?? trackName;
+    if (plainText(options)) return content ?? trackName;
 
     return html`<a
         class="explore-link"
         @click=${singleClick((target) => {
-            void openAlbum(
+            void openAlbumPage(
                 target,
                 albumName,
                 releaseGroupMBID,
@@ -262,11 +323,48 @@ export function trackLink(
     >${content ?? trackName}</a>`;
 }
 
+/**
+ * Route to an artist page, preferring the catalog and falling back to
+ * the library copy.
+ *
+ * Exported because a menu item goes to the same place a name does, and
+ * two routings of "go to this artist" is how the two come to disagree
+ * about an untagged one.
+ */
+export async function openArtistPage(
+    target: EventTarget,
+    artistName: string,
+    mbid: string,
+): Promise<void> {
+    if (mbid) {
+        navigate(target, {
+            view: 'explore-artist-details',
+            artistMBID: mbid,
+            artistName,
+        });
+
+        return;
+    }
+
+    const local = await findLocalArtist(artistName);
+    if (!local) return;
+
+    // The caller's row had no MBID, but the library row for the
+    // same artist may — the grid routes by exactly this field,
+    // so reading it here is what keeps the two paths agreeing.
+    navigate(target, {
+        view: 'explore-artist-details',
+        artistMBID: local.MBID || '',
+        artistName,
+        localArtistId: local.ID,
+    });
+}
+
 /**
  * Route to an album page, preferring the catalog and falling back to
  * the library copy.  `highlight*` marks one track on arrival.
  */
-async function openAlbum(
+export async function openAlbumPage(
     target: EventTarget,
     albumName: string,
     releaseGroupMBID: string,
@@ -337,23 +435,31 @@ export interface CreditPart {
  * @param parts - The credit's parts in position order, if known.
  * @param fallbackName - The credit as a single string.
  * @param fallbackMbid - The primary artist's MBID.
+ * @param options - See `LinkOptions`.
  */
 export function creditLink(
     parts: readonly CreditPart[] | undefined,
     fallbackName: string,
     fallbackMbid: string,
+    options?: LinkOptions,
 ): TemplateResult | string {
     // One part is one link, so it is the fallback rather than a special
     // case — and a zero-part credit reaching here would otherwise
     // render as nothing at all, which is worse than the single-artist
     // answer it replaced.
     if (!parts || parts.length < 2) {
-        return artistLink(fallbackName, fallbackMbid);
+        return artistLink(fallbackName, fallbackMbid, undefined, options);
     }
 
+    // A decomposed credit is rendered from the same parts either way,
+    // so the join phrases survive the suppression and the text reads
+    // as it did — which is `creditText`'s job, and it is the string
+    // the `title=` beside these already uses.
+    if (plainText(options)) return creditText(parts, fallbackName);
+
     return html`${parts.map(
         (part) =>
-            html`${artistLink(part.creditedName, part.artistMbid)}${part.joinPhrase}`,
+            html`${artistLink(part.creditedName, part.artistMbid, undefined, options)}${part.joinPhrase}`,
     )}`;
 }
 

frontend/src/utils/go-to-menu.ts

@@ -0,0 +1,109 @@
+/**
+ * "Go to Artist" / "Go to Album", for the menus that carry a name the
+ * phone stopped drawing as a link (#67).
+ *
+ * `utils/explore-link.ts` renders a plain string below the phone
+ * breakpoint, because a few characters inside a row is not a touch
+ * target and the row's own tap already means "play".  That takes a
+ * destination away, so the row's context menu gives it back — which is
+ * the whole of this issue: the navigation moves, it does not go.
+ *
+ * Three things about it are load-bearing.
+ *
+ * **It is drawn under exactly the condition the link is not.**
+ * `inlineLinksSuppressed()` answers both, so a desktop menu is
+ * untouched (the name beside it is still a link, and a menu that
+ * repeats what the row already offers is furniture) and a phone menu
+ * cannot be missing what the row lost.
+ *
+ * **It goes where the name went.** `openArtistPage` / `openAlbumPage`
+ * are `explore-link`'s own routing, exported rather than reimplemented,
+ * so an untagged artist reaches the library page here for the same
+ * reason and by the same lookup it does from a link.
+ *
+ * **The host says when it is over**, through `onSelect` — every menu in
+ * this app closes itself and most clear their selection, and both are
+ * the host's bookkeeping rather than something a shared item may do on
+ * its behalf.  `onHover` is for the four hosts with a playlist submenu,
+ * which closes on any other item being pointed at.
+ */
+
+import { html, nothing } from 'lit';
+import type { TemplateResult } from 'lit';
+
+import { inlineLinksSuppressed, openArtistPage, openAlbumPage } from './explore-link';
+
+/**
+ * The entities one row or card can send you to.
+ *
+ * Everything is optional because the hosts differ: a track row knows
+ * both, an album card knows only its artist, and an artist page's own
+ * tracklist knows only the album.
+ */
+export interface GoToTarget {
+    artistName?: string;
+    artistMBID?: string;
+    albumName?: string;
+    albumMBID?: string;
+}
+
+export interface GoToHandlers {
+    /** Called before navigating: close the menu, clear the selection. */
+    onSelect?: () => void;
+    /** Called on hover: close a playlist submenu, where the host has one. */
+    onHover?: () => void;
+}
+
+/**
+ * The menu items for a target, or nothing at all where the name beside
+ * them is still a link.
+ */
+export function goToMenuItems(
+    target: GoToTarget | undefined,
+    handlers: GoToHandlers = {},
+): TemplateResult | typeof nothing {
+    if (!target || !inlineLinksSuppressed()) return nothing;
+
+    const artist = target.artistName?.trim();
+    const album = target.albumName?.trim();
+
+    if (!artist && !album) return nothing;
+
+    return html`
+        ${artist
+            ? html`<wa-dropdown-item
+                  data-testid="go-to-artist"
+                  @click=${(e: Event) => {
+                      handlers.onSelect?.();
+                      void openArtistPage(
+                          e.currentTarget as EventTarget,
+                          artist,
+                          target.artistMBID ?? '',
+                      );
+                  }}
+                  @mouseenter=${() => handlers.onHover?.()}
+              >
+                  <wa-icon slot="icon" name="user-group"></wa-icon>
+                  Go to Artist
+              </wa-dropdown-item>`
+            : nothing}
+        ${album
+            ? html`<wa-dropdown-item
+                  data-testid="go-to-album"
+                  @click=${(e: Event) => {
+                      handlers.onSelect?.();
+                      void openAlbumPage(
+                          e.currentTarget as EventTarget,
+                          album,
+                          target.albumMBID ?? '',
+                          artist,
+                      );
+                  }}
+                  @mouseenter=${() => handlers.onHover?.()}
+              >
+                  <wa-icon slot="icon" name="compact-disc"></wa-icon>
+                  Go to Album
+              </wa-dropdown-item>`
+            : nothing}
+    `;
+}

frontend/src/utils/image-prefetch.ts

@@ -0,0 +1,156 @@
+/**
+ * Warm the browser's image cache for the cards a scroll is about to
+ * reach.
+ *
+ * #65: album art pops in while scrolling. The rule this app already
+ * follows is that a row image is `loading="lazy" decoding="async"` and
+ * draws the smallest adequate tier, and both halves are in place —
+ * `cover-grid.getCoverUrl()` and `artists-view`'s avatar both pick
+ * `_sm`/`_md`/`_lg` from the card size and the device pixel ratio. What
+ * is left is *when* the fetch starts: the grids are virtualized, so the
+ * `<img>` does not exist at all until the virtualizer decides to render
+ * its card, and only then can the browser ask for anything.
+ *
+ * The issue's Direction asks for a larger overscan, and that is not
+ * available: `@lit-labs/virtualizer`'s `_overhang` is a hard-coded
+ * 1000px `protected` field on `BaseLayout` with no configuration
+ * surface, so raising it means monkey-patching a private. 1000px is
+ * about two screens on the reference device's 439px viewport, which is
+ * a fraction of a second at speed.
+ *
+ * So the request is issued ahead of the element instead. Cover art and
+ * artist images are plain URLs served by `coverart.Handler` /
+ * `explore`'s image handler under `Cache-Control: public,
+ * max-age=31536000, immutable` — the filenames are content hashes — so
+ * a prefetched image is a cache hit by the time the card is drawn, and
+ * a second pass over the same rows costs nothing at all.
+ *
+ * Three things about it are load-bearing.
+ *
+ * **This is not the `LRUMap` path the issue's Findings warn about.**
+ * That ceiling (`ARTIST_IMAGE_CACHE_LIMIT` and friends) bounds
+ * Explore's base64 data URLs, which are held in JS. A library cover is
+ * a URL, and what retains the bytes is the browser's own HTTP cache,
+ * which evicts on its own terms. What this module retains is the *set
+ * of URLs already asked for*, which is why that set has a cap and
+ * reports itself to `window.__yjCacheStats()` — the measurement the
+ * issue asks for.
+ *
+ * **A window is warmed on both sides of the rendered range.** The
+ * event carries no direction, and scrolling back up needs the same
+ * treatment; the rows behind are already in `requested` from the pass
+ * that rendered them, so the backward half issues nothing in the
+ * common case and is free.
+ *
+ * **An in-flight image is held.** `new Image().src = url` and drop it
+ * is the usual idiom and usually survives, but "usually" is an engine
+ * detail and the engine that matters here is a two-year-old WebView.
+ * The element is kept until it loads or fails, and no longer — nothing
+ * here holds a decoded bitmap on purpose.
+ */
+
+import { registerCacheProbe } from './cache-stats.js';
+import { LRUMap } from './lru-map.js';
+
+/**
+ * How many entries past each edge of the rendered range to warm.
+ *
+ * Entries rather than pixels, because that is what the event reports
+ * and what the caller has an array of. Twelve rows on the phone's
+ * two-column grid and four on a desktop's six, on top of the
+ * virtualizer's own 1000px — enough to cover a flick, and bounded so a
+ * fast scroll through 5 000 albums cannot ask for 5 000 covers.
+ */
+export const PREFETCH_AHEAD = 24;
+
+/** Ceiling on the record of what has already been asked for. */
+export const PREFETCH_MEMORY = 512;
+
+/** URLs already requested; the value is a placeholder, the key is the record. */
+const requested = new LRUMap<string, true>(PREFETCH_MEMORY);
+
+/** Images still loading, held so the request cannot be collected. */
+const inFlight = new Set<HTMLImageElement>();
+
+registerCacheProbe('imagePrefetch', () => {
+    let chars = 0;
+
+    for (const url of requested.keys()) chars += url.length;
+
+    return { entries: requested.size, chars, limit: PREFETCH_MEMORY };
+});
+
+/** Whether this URL has already been asked for. */
+export function imagePrefetched(url: string): boolean {
+    return requested.has(url);
+}
+
+/**
+ * Ask the browser for `url` unless it has already been asked for.
+ * Returns whether a request was issued.
+ */
+export function prefetchImage(url: string): boolean {
+    if (!url || requested.has(url)) return false;
+
+    requested.set(url, true);
+
+    const img = new Image();
+
+    inFlight.add(img);
+
+    const done = () => {
+        inFlight.delete(img);
+    };
+
+    img.addEventListener('load', done, { once: true });
+    img.addEventListener('error', done, { once: true });
+    img.decoding = 'async';
+    img.src = url;
+
+    return true;
+}
+
+/**
+ * Warm the images either side of a virtualizer's rendered range.
+ *
+ * `first`/`last` are the indices the `visibilityChanged` event
+ * reported; `urlOf` returns the image the card at that index will
+ * draw, or `''` where it draws a placeholder. Returns how many
+ * requests were issued, which is what a test can assert on and what
+ * makes "a second run does approximately nothing" checkable.
+ */
+export function prefetchImageWindow<T>(
+    items: readonly T[],
+    first: number,
+    last: number,
+    urlOf: (item: T) => string,
+    ahead: number = PREFETCH_AHEAD,
+): number {
+    if (items.length === 0 || first < 0 || last < first) return 0;
+
+    const from = Math.max(0, first - ahead);
+    const to = Math.min(items.length - 1, last + ahead);
+    let issued = 0;
+
+    // Forward first: it is the direction a scroll is usually going, so
+    // it is the half that has to win the race.
+    for (let i = last + 1; i <= to; i++) {
+        const item = items[i];
+
+        if (item !== undefined && prefetchImage(urlOf(item))) issued++;
+    }
+
+    for (let i = from; i < first; i++) {
+        const item = items[i];
+
+        if (item !== undefined && prefetchImage(urlOf(item))) issued++;
+    }
+
+    return issued;
+}
+
+/** Forget what has been asked for. For tests; the app never needs it. */
+export function resetImagePrefetch(): void {
+    requested.clear();
+    inFlight.clear();
+}

frontend/src/utils/long-press.ts

@@ -1,201 +0,0 @@
-/**
- * Long-press as the touch equivalent of a right-click (plan 016 B2,
- * phase 3).
- *
- * Every context menu in the app opens from a `contextmenu` event —
- * `track-list` and `queue-panel` delegate one on their virtualizer,
- * the card grids and both playlist detail views bind one per row, and
- * `explore-artist-details` binds three. A phone has no right-click, so
- * a phone reached none of them.
- *
- * **This is one document listener, not six components' worth of touch
- * handling.** A press that stays still for `LONG_PRESS_MS` dispatches a
- * synthetic `contextmenu` at the touch point on the element the touch
- * actually landed on, and every existing handler — delegated or
- * per-row, in any shadow root — runs unchanged. Six implementations of
- * a gesture is exactly the fault `ContextMenuController` exists to
- * prevent, and a seam that needs no component to opt in cannot be
- * forgotten by the next component.
- *
- * Three things about it are load-bearing.
- *
- * **The target comes from `composedPath()[0]`, not from
- * `elementFromPoint`**, which stops at the outermost shadow host: every
- * menu in this app is bound inside one, so a synthetic event dispatched
- * on the host reaches a delegated listener and no per-row one.
- *
- * **A browser that already does this must win.** Chromium fires a
- * `contextmenu` on long-press itself; WebKitGTK and the Android WebView
- * vary. So one arriving during the press cancels ours, and one arriving
- * just after ours is swallowed at document capture — where nothing else
- * has seen it yet. The two are told apart by **identity** (a `WeakSet`
- * of the events this module made) rather than by `isTrusted`, so the
- * suppressor cannot eat the event it exists to deliver, the rule holds
- * for anything else in the app that synthesises one, and a test can
- * stand in for a browser that fires its own.
- *
- * **The click that ends the gesture is swallowed.** A row's click
- * selects, and a card's plays; without this, opening a menu also
- * activates the thing under it. It is keyed on the gesture (cleared by
- * the next `pointerdown`) rather than on a time window, so a quick tap
- * on the menu that just opened is not eaten too.
- */
-
-/** How long a press must hold still to mean "menu". */
-export const LONG_PRESS_MS = 500;
-
-/**
- * How far a press may drift and still count. Below a finger's own
- * jitter is a gesture nobody can perform; above ~12px it starts
- * stealing the first frames of a scroll.
- */
-export const MOVE_TOLERANCE_PX = 10;
-
-/** The active installation, so a second call is a no-op rather than a
- *  second listener set. */
-let uninstall: (() => void) | null = null;
-
-/** The events this module dispatched. Identity, not `isTrusted`: see
- *  the note above. */
-const ours = new WeakSet<Event>();
-
-/**
- * Install the gesture. Idempotent; returns the uninstaller (which the
- * tests use — the app installs once and never removes it).
- */
-export function installLongPressContextMenu(): () => void {
-    if (uninstall) return uninstall;
-
-    let timer: ReturnType<typeof setTimeout> | null = null;
-    let originX = 0;
-    let originY = 0;
-    let target: EventTarget | null = null;
-
-    /** A trusted `contextmenu` arrived for this press: the browser has
-     *  it covered. */
-    let nativeSeen = false;
-
-    /** We opened a menu, and the click ending that gesture is not a
-     *  click on anything. */
-    let swallowClick = false;
-
-    /** We dispatched one, so a trusted one arriving now is a duplicate. */
-    let justFired = false;
-
-    const cancel = (): void => {
-        if (timer !== null) clearTimeout(timer);
-
-        timer = null;
-        target = null;
-    };
-
-    const fire = (): void => {
-        timer = null;
-
-        const el = target;
-
-        target = null;
-
-        if (nativeSeen || !el) return;
-
-        justFired = true;
-        swallowClick = true;
-
-        const menu = new MouseEvent('contextmenu', {
-            bubbles: true,
-            cancelable: true,
-            // Or it stops at the shadow root the row lives in, and the
-            // delegated listeners never see it.
-            composed: true,
-            clientX: originX,
-            clientY: originY,
-            button: 2,
-        });
-
-        ours.add(menu);
-        el.dispatchEvent(menu);
-    };
-
-    const onPointerDown = (e: PointerEvent): void => {
-        // A new gesture: whatever the last one left behind is stale.
-        swallowClick = false;
-        justFired = false;
-        nativeSeen = false;
-        cancel();
-
-        if (e.pointerType !== 'touch' || !e.isPrimary) return;
-
-        originX = e.clientX;
-        originY = e.clientY;
-        target = e.composedPath()[0] ?? e.target;
-        timer = setTimeout(fire, LONG_PRESS_MS);
-    };
-
-    const onPointerMove = (e: PointerEvent): void => {
-        if (timer === null) return;
-
-        const drifted =
-            Math.abs(e.clientX - originX) > MOVE_TOLERANCE_PX ||
-            Math.abs(e.clientY - originY) > MOVE_TOLERANCE_PX;
-
-        if (drifted) cancel();
-    };
-
-    const onContextMenu = (e: Event): void => {
-        // Ours. Everything below is about somebody else's.
-        if (ours.has(e)) return;
-
-        if (timer !== null) {
-            // The browser got there first, so stand down rather than
-            // opening the same menu twice.
-            nativeSeen = true;
-            cancel();
-
-            return;
-        }
-
-        if (justFired) {
-            justFired = false;
-            e.preventDefault();
-            e.stopImmediatePropagation();
-        }
-    };
-
-    const onClick = (e: Event): void => {
-        if (!swallowClick) return;
-
-        swallowClick = false;
-        e.preventDefault();
-        e.stopImmediatePropagation();
-    };
-
-    // Capture throughout: a component handler that stops propagation
-    // (every context-menu handler in the app does) must not be able to
-    // hide the gesture from this, and the suppressors have to run
-    // before anything that would act on the event.
-    const opts = { capture: true } as const;
-
-    document.addEventListener('pointerdown', onPointerDown, opts);
-    document.addEventListener('pointermove', onPointerMove, opts);
-    document.addEventListener('pointerup', cancel, opts);
-    document.addEventListener('pointercancel', cancel, opts);
-    document.addEventListener('contextmenu', onContextMenu, opts);
-    document.addEventListener('click', onClick, opts);
-    // A scroll started by something other than the finger (momentum, a
-    // programmatic reveal) still means the press was not a press.
-    document.addEventListener('scroll', cancel, { capture: true, passive: true });
-
-    uninstall = () => {
-        cancel();
-        document.removeEventListener('pointerdown', onPointerDown, opts);
-        document.removeEventListener('pointermove', onPointerMove, opts);
-        document.removeEventListener('pointerup', cancel, opts);
-        document.removeEventListener('pointercancel', cancel, opts);
-        document.removeEventListener('contextmenu', onContextMenu, opts);
-        document.removeEventListener('click', onClick, opts);
-        document.removeEventListener('scroll', cancel, opts);
-        uninstall = null;
-    };
-
-    return uninstall;
-}

frontend/src/utils/selection-controller.ts

@@ -19,6 +19,29 @@ export class SelectionController implements ReactiveController {
     private host: SelectionHost;
     private _selectedItems: Set<string> = new Set();
     private lastSelectedIndex: number | null = null;
+    private _mode = false;
+
+    /**
+     * Whether the list is in *selection mode* (plan 019, #63).
+     *
+     * A finger has no modifier keys, so the ctrl/shift semantics this
+     * controller was written for cannot be expressed by touch at all.
+     * Selection mode is the platform's answer: a long press enters it,
+     * and while it is on, a tap toggles a row instead of playing it.
+     *
+     * It is a flag *here* rather than a fifth concept beside the
+     * controller because all four surfaces that select
+     * (`track-list`, `queue-panel` and both playlist detail views)
+     * already share this class -- so "is this list selecting" has one
+     * answer per list, in the object that already owns the selection
+     * it would otherwise contradict.
+     *
+     * A mouse never sets it. Desktop selection is unchanged and stays
+     * modeless, which is what `handleItemClick` still implements.
+     */
+    get selectionMode(): boolean {
+        return this._mode;
+    }
 
     constructor(host: SelectionHost) {
         this.host = host;
@@ -136,8 +159,64 @@ export class SelectionController implements ReactiveController {
         return true;
     }
 
+    /**
+     * Enter selection mode with `key` selected.
+     *
+     * The row the gesture was made on is selected, rather than the
+     * mode opening empty: a long press is a statement about *that*
+     * row, and an action bar with nothing in it is a mode the user has
+     * to make a second gesture to escape.
+     */
+    enterSelectionMode(key: string, index: number): void {
+        this._mode = true;
+        this._selectedItems = new Set([key]);
+        this.lastSelectedIndex = index;
+        this.host.requestUpdate();
+        this.host.onSelectionChanged?.();
+    }
+
+    /**
+     * Toggle one row, and leave the mode when the last one goes.
+     *
+     * Deselecting everything is how Android's own list surfaces exit
+     * selection mode, and it matters more here than convention: the
+     * mode changes what a tap *means*, so a mode with an empty
+     * selection is a list where tapping does nothing and nothing on
+     * screen says why.
+     */
+    toggleInMode(key: string, index: number): void {
+        const next = new Set(this._selectedItems);
+
+        if (next.has(key)) next.delete(key);
+        else next.add(key);
+
+        this._selectedItems = next;
+        this.lastSelectedIndex = index;
+
+        if (next.size === 0) this._mode = false;
+
+        this.host.requestUpdate();
+        this.host.onSelectionChanged?.();
+    }
+
+    /** Leave selection mode, dropping the selection with it. */
+    exitSelectionMode(): void {
+        if (!this._mode && this._selectedItems.size === 0) return;
+
+        this._mode = false;
+        this._selectedItems = new Set();
+        this.lastSelectedIndex = null;
+        this.host.requestUpdate();
+        this.host.onSelectionChanged?.();
+    }
+
     /** Clear the entire selection. */
     clear(): void {
+        // The mode goes with it: every caller of this means "the
+        // selection is no longer meaningful", and a mode outliving the
+        // selection it was showing is the empty-mode trap above.
+        this._mode = false;
+
         if (this._selectedItems.size === 0) return;
 
         this._selectedItems = new Set();
@@ -176,6 +255,13 @@ export class SelectionController implements ReactiveController {
         if (next.size === this._selectedItems.size) return;
 
         this._selectedItems = next;
+
+        // A refetch that emptied the selection also ends the mode --
+        // otherwise removing the last selected track from the library
+        // leaves the list in a state where a tap selects and the bar
+        // is gone.
+        if (next.size === 0) this._mode = false;
+
         this.host.requestUpdate();
         this.host.onSelectionChanged?.();
     }

frontend/src/utils/swipe-to-queue.ts

@@ -0,0 +1,362 @@
+import { css, html, nothing } from 'lit';
+import type { ReactiveController, ReactiveControllerHost } from 'lit';
+import { classMap } from 'lit/directives/class-map.js';
+
+import { queueStore } from '@store/queue-store';
+import { ICON_QUEUE } from '@utils/icon-language';
+import type { SwipeEvent } from '@utils/touch-gestures';
+
+/**
+ * Swipe a row right to add it to the queue (plan 019, #63).
+ *
+ * This is the *affordance* and the arithmetic, written once, because
+ * three lists want it: `track-list` and both playlist detail views.
+ * It was `track-list`'s own for one phase and is here rather than
+ * copied twice, on the rule the rest of this app is built on — three
+ * copies of "how far is far enough" is three chances for them to
+ * disagree, which is what `utils/library-status.ts` and
+ * `utils/ownership.ts` each exist to have stopped happening.
+ *
+ * The host keeps three things: what a row *is*, what a swipe on it
+ * would queue, and what to call it afterwards. Everything else —
+ * the threshold, the reveal, the settle, the announcement, the
+ * repaint — is here.
+ *
+ * **The queue panel deliberately does not use it.** A right swipe means
+ * *add to the queue* everywhere it exists, and a queue row is already
+ * in the queue; the only thing it could sensibly mean there is
+ * *remove*, which is the same gesture with the opposite effect one
+ * screen away. Removing a queue row is on its own row (the ×), on its
+ * bottom sheet since #60, and on the selection bar #63 gave it.
+ *
+ * Five things about it are load-bearing.
+ *
+ * **Both halves of the device fix are here or next door.**
+ * `swipeRevealStyles` carries `touch-action: pan-y` on `[data-swipe]`,
+ * and `utils/touch-gestures.ts` carries the non-passive
+ * `preventDefault`. Chrome 113's WebView cancels the pointer stream
+ * ~16px into any drag whatever `touch-action` says, and with the
+ * `preventDefault` alone but `touch-action` at `auto` the gesture dies
+ * after one move. Neither works without the other and **both are
+ * correct in Chromium either way**, which is why the component tier
+ * asserts the stylesheet rather than the rendering.
+ *
+ * **The row does not move; its cells do.** A row here is
+ * `contain: strict` with `overflow: hidden`, so translating the row
+ * and counter-translating a pane inside it puts that pane at a
+ * negative offset inside a clipping box, where it is simply not
+ * painted. Sliding the children instead leaves the pane where it was
+ * drawn, clips the cells off the right edge, and needs no wrapper
+ * element in a row that is already a grid.
+ *
+ * **The travel is written to the row's own style, never rendered.**
+ * One render when the gesture starts, one when it crosses the
+ * threshold, one when it ends — a virtualizer re-rendering every
+ * visible row per frame of one finger's travel is exactly what audit
+ * `perf.m1` is about.
+ *
+ * **The threshold is a fraction of the row**, with a floor. The row is
+ * 424x52 on the reference device, so a threshold in bare pixels is a
+ * fraction of a row height on one screen and a third of the width on
+ * the next.
+ *
+ * **It is not only a colour** (WCAG 1.4.1, the rule the playing-row
+ * marker exists for). The pane carries the queue icon and words, the
+ * words change at the threshold, and the outcome goes to a live
+ * region — one glyph throughout, because a tick is `ICON_IN_LIBRARY`
+ * and means *you own this*.
+ */
+
+/** How far along the row a swipe has to reach to mean it. */
+export const SWIPE_COMMIT_FRACTION = 0.3;
+
+/** … and a floor, for a narrow list embedded in a detail page. */
+export const SWIPE_COMMIT_MIN_PX = 72;
+
+/** How long the reveal holds its confirmation before snapping back. */
+const CONFIRM_MS = 550;
+
+/** The snap itself. `swipeRevealStyles` states the same number. */
+const SETTLE_MS = 180;
+
+/** What a swipe on one row would do, as the host understands it. */
+export interface SwipeTarget {
+    /** Which row draws the reveal. */
+    index: number;
+
+    /** The file paths a commit queues, in the order they are shown. */
+    filePaths: string[];
+
+    /** What to call a single track when saying it was added. */
+    label: string;
+}
+
+export interface SwipeToQueueOptions {
+    /**
+     * The row the gesture is on, or null for anything that is not a
+     * swipeable row — a header, a gap, a track with no file.
+     */
+    resolve(e: SwipeEvent): SwipeTarget | null;
+
+    /**
+     * Repaint the rows. A `<lit-virtualizer>` renders through the
+     * `virtualize` directive and reacts to its *own* properties, so a
+     * host update alone leaves the rows exactly as they were.
+     */
+    repaint(): void;
+}
+
+export class SwipeToQueue implements ReactiveController {
+    private host: ReactiveControllerHost;
+    private opts: SwipeToQueueOptions;
+
+    /** Which row is being swiped, and therefore draws a reveal. */
+    private index: number | null = null;
+
+    /** Past the commit threshold: the reveal says so, in words. */
+    private armed = false;
+
+    /** Committed, and holding its confirmation. */
+    private done = false;
+
+    private row: HTMLElement | null = null;
+    private keys: string[] = [];
+    private commitPx = 0;
+    private settleTimer = 0;
+
+    /** What the gesture did, for anyone not watching the row. */
+    announcement = '';
+
+    constructor(host: ReactiveControllerHost, opts: SwipeToQueueOptions) {
+        this.host = host;
+        this.opts = opts;
+        host.addController(this);
+    }
+
+    hostConnected(): void {
+        // No-op; state is component-local.
+    }
+
+    hostDisconnected(): void {
+        window.clearTimeout(this.settleTimer);
+        this.forget();
+    }
+
+    /** Whether this row is the one under the finger. */
+    isSwiping(index: number): boolean {
+        return this.index === index;
+    }
+
+    onSwipeStart = (e: SwipeEvent): void => {
+        // Rightward only. Nothing is bound to a leftward swipe, and
+        // claiming one would take a gesture away to do nothing with it.
+        if (e.detail.dx <= 0) return;
+
+        const target = this.opts.resolve(e);
+
+        if (!target || target.filePaths.length === 0) return;
+
+        const row = (e.target as HTMLElement).closest(
+            '[data-swipe]',
+        ) as HTMLElement | null;
+
+        if (!row) return;
+
+        e.preventDefault();
+
+        this.row = row;
+        this.keys = target.filePaths;
+        this.trackLabel = target.label;
+        this.commitPx = Math.max(
+            SWIPE_COMMIT_MIN_PX,
+            row.getBoundingClientRect().width * SWIPE_COMMIT_FRACTION,
+        );
+        this.armed = false;
+        this.done = false;
+        this.index = target.index;
+        this.host.requestUpdate();
+        this.opts.repaint();
+        this.offset(0);
+    };
+
+    onSwipeMove = (e: SwipeEvent): void => {
+        if (this.index === null) return;
+
+        const dx = Math.min(Math.max(e.detail.dx, 0), this.commitPx * 2);
+        const armed = dx >= this.commitPx;
+
+        if (armed !== this.armed) {
+            this.armed = armed;
+            this.host.requestUpdate();
+            this.opts.repaint();
+        }
+
+        this.offset(dx);
+    };
+
+    onSwipeEnd = (e: SwipeEvent): void => {
+        if (this.index === null) return;
+
+        if (e.detail.canceled || e.detail.dx < this.commitPx) {
+            this.settle(0);
+
+            return;
+        }
+
+        queueStore.addTracksToQueue(this.keys);
+
+        const count = this.keys.length;
+
+        // The reveal is the only thing on screen that says this
+        // happened -- the queue panel may well be closed -- so it holds
+        // its confirmation for a moment rather than vanishing the
+        // instant the finger lifts.
+        this.done = true;
+        this.announcement =
+            count === 1
+                ? `Added ${this.label()} to the queue.`
+                : `Added ${count} tracks to the queue.`;
+        this.host.requestUpdate();
+        this.opts.repaint();
+        this.settle(CONFIRM_MS);
+    };
+
+    /** What is revealed behind the row, in three states. */
+    renderReveal(index: number) {
+        if (this.index !== index) return nothing;
+
+        const count = this.keys.length;
+        const what = count === 1 ? 'to queue' : `${count} tracks to queue`;
+        const words = this.done
+            ? 'Added'
+            : this.armed
+                ? 'Release to add'
+                : `Add ${what}`;
+
+        return html`
+            <div
+                class=${classMap({ 'swipe-reveal': true, armed: this.armed })}
+                aria-hidden="true"
+                data-testid="swipe-reveal"
+            >
+                <wa-icon name=${ICON_QUEUE}></wa-icon>
+                <span>${words}</span>
+            </div>
+        `;
+    }
+
+    /**
+     * What to call a single track, taken when the gesture starts.
+     *
+     * Held rather than looked up at the end, because a swipe outlives
+     * a refetch: the store replaces its array when a play count
+     * changes, which is once a song.
+     */
+    private trackLabel = '';
+
+    private label(): string {
+        return this.trackLabel === '' ? 'the track' : this.trackLabel;
+    }
+
+    /** Write the travel to the row itself, with no render. */
+    private offset(dx: number): void {
+        this.row?.style.setProperty('--yj-swipe-dx', `${dx}px`);
+    }
+
+    /**
+     * Put the row back, after `delay`, and forget the swipe.
+     *
+     * The row element is held rather than looked up again: a
+     * virtualizer recycles its rows, and by the time this runs the
+     * element may be drawing a different track. Clearing the property
+     * off whatever it holds now is right either way, since `index` is
+     * what decides who draws the reveal.
+     */
+    private settle(delay: number): void {
+        const row = this.row;
+
+        window.clearTimeout(this.settleTimer);
+
+        this.settleTimer = window.setTimeout(() => {
+            row?.classList.add('settling');
+            this.offset(0);
+
+            this.settleTimer = window.setTimeout(() => {
+                row?.classList.remove('settling');
+                row?.style.removeProperty('--yj-swipe-dx');
+                this.forget();
+                this.host.requestUpdate();
+                this.opts.repaint();
+            }, SETTLE_MS);
+        }, delay);
+    }
+
+    private forget(): void {
+        this.row = null;
+        this.index = null;
+        this.armed = false;
+        this.done = false;
+    }
+}
+
+/**
+ * The reveal, and the `touch-action` half of what makes the gesture
+ * reach us on the device.
+ *
+ * Keyed on `[data-swipe]` rather than on a class name, so one
+ * stylesheet serves three lists whose rows are called three different
+ * things.
+ */
+export const swipeRevealStyles = css`
+    /* Half of what makes the gesture reach us on Chrome 113's WebView:
+       auto lets it commit to a horizontal pan on the first move past
+       slop, and the pointer stream is cancelled before any threshold
+       can be crossed. The other half is the non-passive preventDefault
+       in utils/touch-gestures.ts, and neither works alone -- both were
+       measured three ways on the phone. Never none: that takes the
+       list's own vertical scrolling with it. */
+    [data-swipe] {
+        touch-action: pan-y;
+    }
+
+    .swipe-reveal {
+        position: absolute;
+        left: 0;
+        top: 0;
+        bottom: 0;
+        width: var(--yj-swipe-dx, 0px);
+        box-sizing: border-box;
+        display: flex;
+        align-items: center;
+        gap: 0.4em;
+        padding-left: 8px;
+        overflow: hidden;
+        white-space: nowrap;
+        pointer-events: none;
+        font-size: var(--yj-text-xs);
+        background-color: var(--yj-bg-elevated, #343a40);
+        color: var(--yj-text-secondary, #b3b3b3);
+    }
+
+    .swipe-reveal.armed {
+        background-color: var(--yj-success, #2f9e44);
+        color: var(--yj-success-fg, #fff);
+    }
+
+    /* The children move, not the row -- see the header. */
+    [data-swipe].swiping > :not(.swipe-reveal) {
+        transform: translateX(var(--yj-swipe-dx, 0px));
+    }
+
+    [data-swipe].settling > * {
+        transition:
+            transform 160ms ease-out,
+            width 160ms ease-out;
+    }
+
+    @media (prefers-reduced-motion: reduce) {
+        [data-swipe].settling > * {
+            transition: none;
+        }
+    }
+`;

frontend/src/utils/touch-gestures.ts

@@ -0,0 +1,619 @@
+/**
+ * The touch gestures, as one document listener (plan 019, #63).
+ *
+ * This replaces `utils/long-press.ts` rather than sitting beside it,
+ * and that is the point: two document listeners both claiming the
+ * 500ms hold is exactly the fault that file's own header warns about.
+ * What it did — one capture listener, the target from
+ * `composedPath()[0]`, the browser's own gesture winning, the trailing
+ * click swallowed — is kept whole. What changes is what the gesture
+ * *means*.
+ *
+ * **A gesture is announced, not acted on.** Two composed, cancelable
+ * events are dispatched on the element the finger actually landed on:
+ *
+ *   `yj-tap`         a short press that did not drift
+ *   `yj-long-press`  a press that held still for LONG_PRESS_MS
+ *   `yj-swipe-start` a press that has travelled decisively sideways
+ *
+ * A claimed swipe is then followed by `yj-swipe-move` and one
+ * `yj-swipe-end`, which is guaranteed: a swipe that the browser or a
+ * second finger takes away still ends, with `canceled` set, so the
+ * affordance a component put on screen always has something to snap
+ * back from.
+ *
+ * A component that wants the gesture handles it and calls
+ * `preventDefault()`. Nothing else changes. That shape is what lets
+ * this reassign the hold without touching a single one of the fourteen
+ * context menus downstream of it: **an unclaimed `yj-long-press` still
+ * becomes a synthetic `contextmenu`**, so a card grid, an Explore
+ * result or a playlist row behaves exactly as it did, and only the
+ * lists that opt in get selection mode.
+ *
+ * The same rule keeps taps honest. An unclaimed `yj-tap` does nothing
+ * at all and the browser's click follows normally, so every button,
+ * link and checkbox in the app is untouched by this file. Only a
+ * claimed tap has its click swallowed — otherwise playing a track
+ * would also select it.
+ *
+ * Five things are load-bearing.
+ *
+ * **The predicate is the pointer, not the platform** (plan 019,
+ * decision 1). `pointerType === 'touch'`, per event — so an Android
+ * tablet over 600px, a touchscreen laptop with a mouse also plugged
+ * in, and a narrow desktop window are all right for free, and there is
+ * no second declaration of what a phone does. Keyed on a viewport
+ * width, the first of those three gets desktop semantics on a
+ * touchscreen, which is the inversion #63 exists to fix, on the
+ * platform it exists for.
+ *
+ * **There is no double-tap**, and it is not an omission — see plan
+ * 019, decision 2. Measured on the reference device, the play command
+ * to `TrackChanged` is ~100ms; a double-tap discriminator has to hold
+ * every tap for the app's own `DOUBLE_CLICK_GRACE_MS` of 250 before it
+ * can act, which is 3.5x the primary interaction in the app to reach a
+ * menu that long-press already reaches.
+ *
+ * **The target comes from `composedPath()[0]`**, not
+ * `elementFromPoint`, which stops at the outermost shadow host: every
+ * list in this app delegates inside one, so an event dispatched on the
+ * host reaches a delegated listener and no per-row one.
+ *
+ * **A browser that fires its own `contextmenu` is a trigger, not a
+ * competitor**, and that is a change from `long-press.ts` rather than
+ * an inherited rule. It used to stand down when a trusted
+ * `contextmenu` arrived, because both paths ended in the same place: a
+ * context menu. They no longer do — ours may end in selection mode —
+ * so standing down means the gesture silently does the *old* thing.
+ *
+ * Measured on the reference device, which is the only tier that can
+ * see this: Chrome 113's WebView fires its own `contextmenu` on a long
+ * press, so a hold on a track row opened the context menu and
+ * `yj-long-press` was never announced at all. Every test in the
+ * component tier passed, because dispatched pointer events do not make
+ * a browser synthesise one.
+ *
+ * So a trusted `contextmenu` arriving mid-press *becomes* the long
+ * press: `yj-long-press` is announced from it, and only if a component
+ * claims it is the native event suppressed. Unclaimed, it propagates
+ * untouched and opens the menu it always did — which is the same
+ * "browser wins" outcome, now reached by asking rather than assuming.
+ *
+ * Ours and the browser's are still told apart by identity rather than
+ * `isTrusted` — a `WeakSet` of the events this module made — so the
+ * suppressor cannot eat the event it exists to deliver, and a test can
+ * stand in for a browser that fires one.
+ *
+ * **The click swallow is keyed on the gesture**, cleared by the next
+ * `pointerdown` rather than by a time window, so the first tap on a
+ * sheet that just opened is not eaten too.
+ *
+ * ## The swipe runs on touch events, and that is not a style choice
+ *
+ * Everything above is Pointer Events. The swipe is not, and the reason
+ * is measured on the reference device rather than reasoned about:
+ * **Chrome 113's Android WebView cancels the pointer stream ~16px into
+ * any drag, whatever `touch-action` says.** Three values were tried on
+ * a track row, driving a real finger with `adb shell input swipe`:
+ *
+ * ```
+ * touch-action: auto   pointerdown, 1 move,  pointercancel
+ * touch-action: pan-y  pointerdown, 2 moves, pointercancel
+ * touch-action: none   pointerdown, 2 moves, pointercancel
+ * ```
+ *
+ * `touchmove` kept firing throughout all three. So a swipe recognised
+ * from `pointermove` is a swipe that dies 16px in — plan 019 predicted
+ * the class of failure ("works in Chromium and not on the phone") and
+ * named `touch-action: pan-y` as the fix; it is half of it.
+ *
+ * The other half is that **a non-passive `touchmove` that calls
+ * `preventDefault()` is what keeps the gesture ours**. With it, the
+ * same swipe ran to 12 moves and a `pointerup` at full travel.
+ *
+ * Both halves are required, and that was measured too: with the
+ * `preventDefault` in place but `touch-action` back at `auto`, the
+ * gesture died after **one** move. The reading is that `auto` lets the
+ * browser commit to a horizontal pan on the first move past slop —
+ * before any threshold of ours can have been crossed — while `pan-y`
+ * leaves it undecided long enough for the second move to claim it.
+ *
+ * So a surface that wants a horizontal swipe declares
+ * `touch-action: pan-y` (`track-list`'s `.track-row` does) *and* gets
+ * this module's `preventDefault`. Neither alone works on the device,
+ * and **both work in Chromium either way**, which is exactly why this
+ * paragraph exists rather than a test.
+ *
+ * `touch-action: none` is the one value to avoid: it also takes the
+ * list's vertical scrolling away, which was measured as a list that
+ * would not move.
+ *
+ * Two consequences of the touch listener worth knowing.
+ *
+ * **It is non-passive, which costs the compositor's scroll fast path**
+ * for the first touchmoves of every scroll, until the browser starts
+ * scrolling and stops waiting on us. That is the standard price of a
+ * horizontal gesture in a scroller and it is paid once per gesture,
+ * not per frame; a vertical drag on the device still scrolls the
+ * virtualizer 81px on the same measurement that the horizontal one
+ * survives.
+ *
+ * **The tie breaks toward scrolling**, deliberately and in that order:
+ * vertical drift past the tolerance vetoes the swipe outright, and a
+ * gesture that is not *strictly* more horizontal than vertical is the
+ * scroller's. A list that will not scroll is unusable; a swipe that
+ * needs a second try is not.
+ */
+
+/** How long a press must hold still to mean "long press". */
+export const LONG_PRESS_MS = 500;
+
+/**
+ * How far a press may drift and still count. Below a finger's own
+ * jitter is a gesture nobody can perform; above ~12px it starts
+ * stealing the first frames of a scroll.
+ */
+export const MOVE_TOLERANCE_PX = 10;
+
+/**
+ * How far a press must travel sideways before it is a swipe.
+ *
+ * It has a ceiling the other constants do not: the browser's own
+ * decision is made a little past this, so a threshold much higher is a
+ * gesture the device never delivers. Measured, the second `touchmove`
+ * of an `adb input swipe` lands at ~19px and the pointer stream dies
+ * just after it, so 12 is inside that window with room for a slower
+ * finger.
+ */
+export const SWIPE_START_PX = 12;
+
+/** Detail carried by both gesture events. */
+export interface GestureDetail {
+    /** Where the finger was, in client coordinates — a menu opens here. */
+    x: number;
+    y: number;
+}
+
+/** Detail carried by the three swipe events. */
+export interface SwipeDetail {
+    /** Travel from where the finger landed. Signed: right is positive. */
+    dx: number;
+    dy: number;
+    /**
+     * The gesture was taken away rather than finished — a second
+     * finger, a `touchcancel`, a scroll underneath. Only ever true on
+     * `yj-swipe-end`, and it is the difference between "do the thing"
+     * and "put the row back".
+     */
+    canceled: boolean;
+}
+
+export type GestureEvent = CustomEvent<GestureDetail>;
+export type SwipeEvent = CustomEvent<SwipeDetail>;
+
+declare global {
+    interface HTMLElementEventMap {
+        'yj-tap': GestureEvent;
+        'yj-long-press': GestureEvent;
+        'yj-swipe-start': SwipeEvent;
+        'yj-swipe-move': SwipeEvent;
+        'yj-swipe-end': SwipeEvent;
+    }
+}
+
+/** The active installation, so a second call is a no-op rather than a
+ *  second listener set. */
+let uninstall: (() => void) | null = null;
+
+/** The events this module dispatched. Identity, not `isTrusted`. */
+const ours = new WeakSet<Event>();
+
+/**
+ * Install the gestures. Idempotent; returns the uninstaller (which the
+ * tests use — the app installs once and never removes it).
+ */
+export function installTouchGestures(): () => void {
+    if (uninstall) return uninstall;
+
+    let timer: ReturnType<typeof setTimeout> | null = null;
+    let originX = 0;
+    let originY = 0;
+    let target: EventTarget | null = null;
+
+    /** The press is still a candidate for a tap: it has neither
+     *  drifted nor become a long press. */
+    let tapCandidate = false;
+
+    /** A trusted `contextmenu` arrived for this press: the browser has
+     *  it covered. */
+    let nativeSeen = false;
+
+    /** A gesture was claimed, and the click ending it is not a click on
+     *  anything. */
+    let swallowClick = false;
+
+    /**
+     * This press has already produced its outcome, so a trusted
+     * `contextmenu` arriving now is a duplicate of it.
+     *
+     * It covers **both** outcomes, and that is a fix rather than a
+     * tidy-up. `nativeSeen` handles the browser's menu arriving
+     * *during* the hold; the reverse order was never handled, and it
+     * happens: measured on the reference device over four holds, two
+     * of them fired our 500ms timer and then delivered a trusted
+     * `contextmenu` 50-70ms later, which nothing suppressed — so the
+     * context menu opened on top of the selection bar, intermittently,
+     * on exactly the surface #63 exists to have changed. Neither the
+     * component tier nor the e2e tier can see it: no browser they run
+     * in synthesises a `contextmenu` from a dispatched press at all.
+     */
+    let justFired = false;
+
+    // --- the swipe, which runs on touch events; see the header ------
+
+    /** Where the finger landed, and what it landed on. */
+    let swipeTarget: EventTarget | null = null;
+    let swipeOriginX = 0;
+    let swipeOriginY = 0;
+
+    /** The last travel, kept so a `touchcancel` — which carries no
+     *  coordinates for a touch that is already gone — can still say how
+     *  far the row had moved. */
+    let lastDx = 0;
+    let lastDy = 0;
+
+    /** A component claimed the swipe: it is ours until the finger
+     *  lifts, and every `touchmove` is prevented. */
+    let swiping = false;
+
+    /** This press can no longer become a swipe — it went vertical, a
+     *  second finger arrived, or nobody claimed it. */
+    let swipeVetoed = false;
+
+    const cancel = (): void => {
+        if (timer !== null) clearTimeout(timer);
+
+        timer = null;
+        target = null;
+        tapCandidate = false;
+    };
+
+    /**
+     * Announce a gesture on the element the finger landed on.
+     * Returns whether a component claimed it.
+     */
+    const announce = (name: 'yj-tap' | 'yj-long-press', el: EventTarget): boolean => {
+        const event: GestureEvent = new CustomEvent<GestureDetail>(name, {
+            bubbles: true,
+            cancelable: true,
+            // Or it stops at the shadow root the row lives in, and the
+            // delegated listeners never see it.
+            composed: true,
+            detail: { x: originX, y: originY },
+        });
+
+        ours.add(event);
+        el.dispatchEvent(event);
+
+        return event.defaultPrevented;
+    };
+
+    const fireContextMenu = (el: EventTarget): void => {
+        justFired = true;
+
+        const menu = new MouseEvent('contextmenu', {
+            bubbles: true,
+            cancelable: true,
+            composed: true,
+            clientX: originX,
+            clientY: originY,
+            button: 2,
+        });
+
+        ours.add(menu);
+        el.dispatchEvent(menu);
+    };
+
+    const onLongPress = (): void => {
+        timer = null;
+        tapCandidate = false;
+
+        const el = target;
+
+        target = null;
+
+        if (nativeSeen || !el) return;
+
+        // The gesture happened either way, so the click that ends it is
+        // never a click on anything -- whether a list claimed it for
+        // selection mode or a card grid let it fall through to a menu.
+        swallowClick = true;
+
+        // The press is answered, so a trusted `contextmenu` for it is
+        // late rather than new. `fireContextMenu` sets this too; it is
+        // set here as well so the *claimed* branch is covered, which
+        // is the branch that was showing a menu over the bar.
+        justFired = true;
+
+        // An unclaimed long press is what it has always been. This is
+        // the whole reason the fourteen context menus need no change.
+        if (!announce('yj-long-press', el)) fireContextMenu(el);
+    };
+
+    const onPointerDown = (e: PointerEvent): void => {
+        // A new gesture: whatever the last one left behind is stale.
+        swallowClick = false;
+        justFired = false;
+        nativeSeen = false;
+        cancel();
+
+        if (e.pointerType !== 'touch' || !e.isPrimary) return;
+
+        originX = e.clientX;
+        originY = e.clientY;
+        target = e.composedPath()[0] ?? e.target;
+        tapCandidate = true;
+        timer = setTimeout(onLongPress, LONG_PRESS_MS);
+    };
+
+    /**
+     * Announce a swipe on the element the finger landed on.
+     * Returns whether a component claimed it (only `start` asks).
+     */
+    const announceSwipe = (
+        name: 'yj-swipe-start' | 'yj-swipe-move' | 'yj-swipe-end',
+        el: EventTarget,
+        canceled = false,
+    ): boolean => {
+        const event: SwipeEvent = new CustomEvent<SwipeDetail>(name, {
+            bubbles: true,
+            cancelable: name === 'yj-swipe-start',
+            composed: true,
+            detail: { dx: lastDx, dy: lastDy, canceled },
+        });
+
+        ours.add(event);
+        el.dispatchEvent(event);
+
+        return event.defaultPrevented;
+    };
+
+    /**
+     * End a claimed swipe, once.
+     *
+     * Every exit from a swipe comes through here so that `yj-swipe-end`
+     * is guaranteed: a component that has put a reveal on screen and a
+     * row half off its own left edge has no other way to learn the
+     * gesture is over.
+     */
+    const endSwipe = (canceled: boolean): void => {
+        const el = swipeTarget;
+
+        swipeTarget = null;
+
+        if (!swiping) return;
+
+        swiping = false;
+
+        if (!el) return;
+
+        // The gesture happened, so the click that ends it is not a
+        // click on the row it ended over.
+        swallowClick = true;
+        announceSwipe('yj-swipe-end', el, canceled);
+    };
+
+    const onTouchStart = (e: TouchEvent): void => {
+        endSwipe(true);
+
+        lastDx = 0;
+        lastDy = 0;
+
+        // A second finger is a pinch or a scroll, never one of ours.
+        swipeVetoed = e.touches.length !== 1;
+
+        if (swipeVetoed) return;
+
+        const touch = e.touches[0];
+
+        if (!touch) return;
+
+        swipeOriginX = touch.clientX;
+        swipeOriginY = touch.clientY;
+        // `composedPath()[0]` for the reason the press path uses it: a
+        // list delegates inside its own shadow root.
+        swipeTarget = e.composedPath()[0] ?? e.target;
+    };
+
+    const onTouchMove = (e: TouchEvent): void => {
+        if (swipeVetoed || !swipeTarget) return;
+
+        if (e.touches.length !== 1) {
+            endSwipe(true);
+            swipeVetoed = true;
+
+            return;
+        }
+
+        const touch = e.touches[0];
+
+        if (!touch) return;
+
+        lastDx = touch.clientX - swipeOriginX;
+        lastDy = touch.clientY - swipeOriginY;
+
+        if (swiping) {
+            // This is what keeps the stream alive on the device. It is
+            // only ever reached for a *claimed* swipe, so nothing that
+            // scrolls is ever prevented.
+            e.preventDefault();
+            announceSwipe('yj-swipe-move', swipeTarget);
+
+            return;
+        }
+
+        // Vertical first: past the tolerance the list has it, and a
+        // gesture that is exactly diagonal is the list's too.
+        if (
+            Math.abs(lastDy) > MOVE_TOLERANCE_PX &&
+            Math.abs(lastDy) >= Math.abs(lastDx)
+        ) {
+            swipeVetoed = true;
+            swipeTarget = null;
+
+            return;
+        }
+
+        if (
+            Math.abs(lastDx) < SWIPE_START_PX ||
+            Math.abs(lastDx) <= Math.abs(lastDy)
+        ) {
+            return;
+        }
+
+        if (!announceSwipe('yj-swipe-start', swipeTarget)) {
+            // Nobody wants it. Leave the gesture to the browser rather
+            // than holding it open for the rest of the press.
+            swipeVetoed = true;
+            swipeTarget = null;
+
+            return;
+        }
+
+        swiping = true;
+
+        // It is not a tap and it is not a hold.
+        cancel();
+        e.preventDefault();
+    };
+
+    const onTouchEnd = (): void => {
+        endSwipe(false);
+    };
+
+    const onTouchCancel = (): void => {
+        endSwipe(true);
+    };
+
+    const onPointerMove = (e: PointerEvent): void => {
+        if (timer === null) return;
+
+        const drifted =
+            Math.abs(e.clientX - originX) > MOVE_TOLERANCE_PX ||
+            Math.abs(e.clientY - originY) > MOVE_TOLERANCE_PX;
+
+        // A drifted press is neither gesture -- it is a scroll, and the
+        // virtualizer's, not ours.
+        if (drifted) cancel();
+    };
+
+    const onPointerUp = (): void => {
+        const el = target;
+        const wasTap = tapCandidate && timer !== null;
+
+        // Clears the long-press timer, so a tap cannot also become one.
+        cancel();
+
+        if (!wasTap || !el) return;
+
+        // Only a *claimed* tap swallows its click. An unclaimed one has
+        // to fall through untouched, or every button in the app stops
+        // working.
+        if (announce('yj-tap', el)) swallowClick = true;
+    };
+
+    const onContextMenu = (e: Event): void => {
+        // Ours. Everything below is about somebody else's.
+        if (ours.has(e)) return;
+
+        if (timer !== null) {
+            // The browser recognised the same hold this was timing.
+            // Use its event as the trigger rather than racing it --
+            // and rather than standing down, which is what the old
+            // rule did and which now silently means "do the thing this
+            // gesture used to do".
+            const el = e.composedPath()[0] ?? e.target;
+
+            nativeSeen = true;
+            cancel();
+
+            if (!el) return;
+
+            swallowClick = true;
+
+            // Claimed: the component wants selection mode, so the
+            // browser's menu must not also open. Unclaimed: let it
+            // through exactly as before.
+            if (announce('yj-long-press', el)) {
+                e.preventDefault();
+                e.stopImmediatePropagation();
+            }
+
+            return;
+        }
+
+        if (justFired) {
+            justFired = false;
+            e.preventDefault();
+            e.stopImmediatePropagation();
+        }
+    };
+
+    const onClick = (e: Event): void => {
+        if (!swallowClick) return;
+
+        swallowClick = false;
+        e.preventDefault();
+        e.stopImmediatePropagation();
+    };
+
+    // Capture throughout: a component handler that stops propagation
+    // (every context-menu handler in the app does) must not be able to
+    // hide the gesture from this, and the suppressors have to run
+    // before anything that would act on the event.
+    const opts = { capture: true } as const;
+
+    // Non-passive, because `onTouchMove` has to be able to prevent the
+    // default for a claimed swipe -- see the header. The other three
+    // are passive: they only read.
+    const blocking = { capture: true, passive: false } as const;
+    const listening = { capture: true, passive: true } as const;
+
+    /** A surface moved under the finger: neither gesture survives it. */
+    const abort = (): void => {
+        endSwipe(true);
+        cancel();
+    };
+
+    document.addEventListener('pointerdown', onPointerDown, opts);
+    document.addEventListener('pointermove', onPointerMove, opts);
+    document.addEventListener('pointerup', onPointerUp, opts);
+    document.addEventListener('pointercancel', cancel, opts);
+    document.addEventListener('contextmenu', onContextMenu, opts);
+    document.addEventListener('click', onClick, opts);
+    document.addEventListener('touchstart', onTouchStart, listening);
+    document.addEventListener('touchmove', onTouchMove, blocking);
+    document.addEventListener('touchend', onTouchEnd, listening);
+    document.addEventListener('touchcancel', onTouchCancel, listening);
+    // A scroll started by something other than the finger (momentum, a
+    // programmatic reveal) still means the press was not a press.
+    document.addEventListener('scroll', abort, listening);
+
+    uninstall = () => {
+        abort();
+        document.removeEventListener('pointerdown', onPointerDown, opts);
+        document.removeEventListener('pointermove', onPointerMove, opts);
+        document.removeEventListener('pointerup', onPointerUp, opts);
+        document.removeEventListener('pointercancel', cancel, opts);
+        document.removeEventListener('contextmenu', onContextMenu, opts);
+        document.removeEventListener('click', onClick, opts);
+        document.removeEventListener('touchstart', onTouchStart, opts);
+        document.removeEventListener('touchmove', onTouchMove, opts);
+        document.removeEventListener('touchend', onTouchEnd, opts);
+        document.removeEventListener('touchcancel', onTouchCancel, opts);
+        document.removeEventListener('scroll', abort, opts);
+        uninstall = null;
+    };
+
+    return uninstall;
+}

frontend/test/components/art-prefetch.test.ts

@@ -0,0 +1,190 @@
+/**
+ * The grids ask for the art below the fold before the card exists
+ * (#65).
+ *
+ * Reported as "scrolling through albums, the art pops in". The cards
+ * already draw the smallest adequate tier and are already
+ * `loading="lazy"`, so what was left is *when*: `<lit-virtualizer>`
+ * renders about 1000px past the viewport and the `<img>` — and
+ * therefore the request — does not exist until it does. On the
+ * reference device that is about two screens.
+ *
+ * These assert the mechanism, since no tier here can photograph a
+ * pop-in: that the rows past the rendered range are requested, that
+ * the request is for the same tier the card will draw, and that the
+ * window has an end — an unbounded prefetch of a 5 000-album library
+ * is the failure this trades against.
+ *
+ * What is *not* asserted here is that a rendered card was never
+ * prefetched. It often was, honestly: the grid lays out more than once
+ * on mount, so a row warmed by the first pass is drawn by the second,
+ * which is the whole point. The rule that a single pass skips its own
+ * rendered range is `image-prefetch.test.ts`'s, where one call can be
+ * looked at on its own.
+ */
+import { describe, expect, it, beforeEach } from 'vitest';
+import type { LitElement } from 'lit';
+
+import '@components/cover-grid/cover-grid';
+import '@components/artists-view/artists-view';
+import { emit, stub, flush, resetHarness } from '@test/support/harness';
+import { Events } from '../../src/events';
+import { fixture, shadowAll } from '@test/support/render';
+import {
+  PREFETCH_AHEAD,
+  imagePrefetched,
+  resetImagePrefetch,
+} from '@utils/image-prefetch';
+
+/** Enough albums that the virtualizer's own window is nowhere near the end. */
+const ALBUMS = Array.from({ length: 400 }, (_, i) => {
+  const n = String(i + 1).padStart(4, '0');
+
+  return {
+    ID: i + 1,
+    Name: `Album ${n}`,
+    ArtistName: 'Aurora Fields',
+    Year: 2020,
+    CoverArtPath: `/covers/${n}.jpg`,
+    CoverArtSmall: `/covers/${n}_sm.jpg`,
+    CoverArtMedium: `/covers/${n}_md.jpg`,
+    CoverArtLarge: `/covers/${n}_lg.jpg`,
+  };
+});
+
+const ARTISTS = Array.from({ length: 400 }, (_, i) => {
+  const n = String(i + 1).padStart(4, '0');
+
+  return {
+    ID: i + 1,
+    Name: `Artist ${n}`,
+    AlbumCount: 2,
+    TrackCount: 9,
+    ImageSmall: `/artists/${n}_sm.jpg`,
+    ImageMedium: `/artists/${n}_md.jpg`,
+    ImageLarge: `/artists/${n}_lg.jpg`,
+  };
+});
+
+/** Give the virtualizer a viewport; a zero-height host renders nothing. */
+function sized(el: HTMLElement): void {
+  el.style.display = 'block';
+  el.style.height = '600px';
+  el.style.width = '900px';
+}
+
+async function settle(el: LitElement): Promise<void> {
+  await flush();
+  await el.updateComplete;
+  await new Promise((r) => setTimeout(r, 200));
+}
+
+/** The `src` of every card the grid actually rendered. */
+function renderedSources(el: LitElement, selector: string): string[] {
+  return shadowAll(el, selector)
+    .map((img) => (img as HTMLImageElement).getAttribute('src') ?? '')
+    .filter(Boolean);
+}
+
+/**
+ * The last index the virtualizer has rendered, read off the cards
+ * rather than counted: the rendered range is what the prefetch window
+ * is measured from, and a count assumes it starts at 0 and has no
+ * gaps.
+ */
+function lastRenderedIndex(el: LitElement, selector: string): number {
+  const indices = shadowAll(el, selector).map((card) =>
+    Number(card.getAttribute('data-index')),
+  );
+
+  return Math.max(...indices);
+}
+
+/**
+ * The tier the cards chose, read off a rendered card rather than
+ * recomputed — the point of the assertion is that the prefetch and the
+ * card agree, so deriving both from the same ladder here would prove
+ * nothing.
+ */
+function tierSuffix(src: string): string {
+  const m = /_(sm|md|lg)\.jpg$/.exec(src);
+
+  return m ? `_${m[1]}` : '';
+}
+
+beforeEach(() => {
+  resetHarness();
+  resetImagePrefetch();
+  localStorage.clear();
+  stub('library.Library.GetAlbums', ALBUMS);
+  stub('library.Library.GetArtists', ARTISTS);
+  stub('library.Library.GetTracks', []);
+  stub('library.Library.GetGenres', []);
+  emit(Events.LibraryScanComplete);
+});
+
+describe('the albums grid warms the covers below the fold', () => {
+  it('asks for the covers past the rendered range, in the tier the card draws', async () => {
+    const el = await fixture<LitElement>('cover-grid');
+
+    sized(el);
+    await settle(el);
+
+    const rendered = renderedSources(el, 'img.cover-image');
+
+    expect(rendered.length).toBeGreaterThan(0);
+
+    const tier = tierSuffix(rendered[0]!);
+    const url = (index: number) =>
+      `/covers/${String(index + 1).padStart(4, '0')}${tier}.jpg`;
+
+    // The grid starts at the top and never scrolls here, so the whole
+    // window lies past the last card drawn.
+    const last = lastRenderedIndex(el, '.album-card');
+
+    expect(imagePrefetched(url(last + 1))).toBe(true);
+    expect(imagePrefetched(url(last + PREFETCH_AHEAD))).toBe(true);
+  });
+
+  it('stops at the end of the window rather than warming the library', async () => {
+    const el = await fixture<LitElement>('cover-grid');
+
+    sized(el);
+    await settle(el);
+
+    const rendered = renderedSources(el, 'img.cover-image');
+    const tier = tierSuffix(rendered[0]!);
+    const url = (index: number) =>
+      `/covers/${String(index + 1).padStart(4, '0')}${tier}.jpg`;
+
+    // Not "exactly `last + PREFETCH_AHEAD`": the grid lays out more
+    // than once on mount and each pass warms a window from wherever
+    // the rendered range was then, so the reachable set is a few
+    // windows wide. The property that matters is that it is a window
+    // at all rather than the library.
+    expect(imagePrefetched(url(399))).toBe(false);
+    expect(window.__yjCacheStats?.()['imagePrefetch']?.entries ?? 0)
+      .toBeLessThan(ALBUMS.length / 2);
+  });
+});
+
+describe('the artists grid warms its avatars the same way', () => {
+  it('asks for the avatars past the rendered range', async () => {
+    const el = await fixture<LitElement>('artists-view');
+
+    sized(el);
+    await settle(el);
+
+    const rendered = renderedSources(el, 'img.avatar-image');
+
+    expect(rendered.length).toBeGreaterThan(0);
+
+    const tier = tierSuffix(rendered[0]!);
+    const last = lastRenderedIndex(el, '.artist-card');
+    const url = (index: number) =>
+      `/artists/${String(index + 1).padStart(4, '0')}${tier}.jpg`;
+
+    expect(imagePrefetched(url(last + 1))).toBe(true);
+    expect(imagePrefetched(url(399))).toBe(false);
+  });
+});

frontend/test/components/bottom-nav.test.ts

@@ -193,4 +193,175 @@ describe('bottom-nav', () => {
     expect(shadow<HTMLElement>(el, 'app-sidebar')?.hasAttribute('expanded'))
       .toBe(true);
   });
+
+  it('draws "More" as a sheet rising from the bottom', async () => {
+    const el = await fixture<Nav>('bottom-nav');
+    const drawer = shadow<HTMLElement>(el, 'wa-drawer');
+
+    // #71. A side drawer is a desktop shape: it opened away from the
+    // thumb that asked for it and drew a 200px column of a 424px
+    // screen. `placement` is the whole of the change to *where* it
+    // comes from, and `without-header` is what makes it the same sheet
+    // `menu-surface` draws rather than a second pattern with a title
+    // bar and a close button.
+    expect(drawer?.getAttribute('placement')).toBe('bottom');
+    expect(drawer?.hasAttribute('without-header')).toBe(true);
+
+    // Named all the same: `nameDialog`'s documented aria-label path,
+    // since without-header renders no heading to point at.
+    expect(drawer?.getAttribute('label')).toBe('All views');
+  });
+
+  it('leaves exactly one scroll container, and it is the sheet body', async () => {
+    const el = await fixture<Nav>('bottom-nav');
+    const drawer = shadow<HTMLElement & { open: boolean }>(el, 'wa-drawer');
+
+    if (!drawer) throw new Error('no drawer');
+
+    const shown = once(drawer, 'wa-after-show');
+
+    shadow<HTMLButtonElement>(el, '[data-testid="tab-more"]')?.click();
+    await shown;
+    await update(el, {});
+
+    // The report is "only part of the screen scrolls under my finger",
+    // and the cause is three boxes that each scroll: the dialog, its
+    // body, and the sidebar's own overflow-y host. Which one a drag
+    // moves depends on where the finger landed.
+    const dialog = drawer.shadowRoot?.querySelector('[part~="dialog"]');
+    const body = drawer.shadowRoot?.querySelector('[part~="body"]');
+    const sidebar = shadow<HTMLElement>(el, 'app-sidebar');
+
+    if (!dialog || !body || !sidebar) throw new Error('no sheet');
+
+    expect(getComputedStyle(dialog).overflowY).toBe('hidden');
+    expect(getComputedStyle(body).overflowY).toBe('auto');
+    expect(getComputedStyle(sidebar).overflowY).toBe('visible');
+
+    // And the one that does scroll keeps it to itself, or reaching the
+    // end of the destinations scrolls the page behind the sheet.
+    expect(getComputedStyle(body).overscrollBehaviorY).toBe('contain');
+  });
+
+  it('says where the fold is, in the sheet\'s own colour', async () => {
+    const el = await fixture<Nav>('bottom-nav');
+    const drawer = shadow<HTMLElement & { open: boolean }>(el, 'wa-drawer');
+
+    if (!drawer) throw new Error('no drawer');
+
+    const shown = once(drawer, 'wa-after-show');
+
+    shadow<HTMLButtonElement>(el, '[data-testid="tab-more"]')?.click();
+    await shown;
+
+    const body = drawer.shadowRoot?.querySelector('[part~="body"]');
+
+    if (!body) throw new Error('no body part to scroll');
+
+    const style = getComputedStyle(body);
+
+    // #210. This list does not fit the phone — measured at 424x439,
+    // `scrollHeight` 412 against `clientHeight` 373 with the seed's
+    // eight destinations — and said nothing about it, which where the
+    // cut lands on a row boundary reads as the end of the list.
+    //
+    // The mechanism is #207's and is asserted the same way: the pair of
+    // attachments *is* the feature. A cover of the sheet's own colour
+    // painted at the end of the content (`local`) over a shadow pinned
+    // to the box (`scroll`), so the fade is absent on a sheet that
+    // fits, present the moment one does not, and gone again at the end.
+    expect(
+      style.backgroundAttachment,
+      'the cover must be local and the shadow must not',
+    ).toBe('local, scroll');
+    expect(style.backgroundPosition).toBe('50% 100%, 50% 100%');
+    expect(style.backgroundSize).toBe('100% 32px, 100% 32px');
+
+    // And the colour is the local half of a shared rule: this sheet
+    // paints the sidebar's `--yj-bg-surface` (#212529) rather than the
+    // menus' elevated grey, or the fade draws the *other* sheet's
+    // colour across the bottom of this one — which is the seam a
+    // shared fragment would otherwise reintroduce.
+    expect(style.backgroundImage).toMatch(
+      /^linear-gradient\(rgb\(33, 37, 41\), rgb\(33, 37, 41\)\)/,
+    );
+
+    // And nothing paints over it. The sidebar's host carries the same
+    // grey, which inside the sheet is a second opaque copy of the
+    // surface drawn on top of these layers -- measured at 424x439 with
+    // the rule removed, the last 32px read a flat 52,58,64 with 39px
+    // still below, so the fade was painted and covered. That is
+    // `.context-menu-panel[data-sheet]`'s transparency, one sheet over.
+    const sidebar = shadow<HTMLElement>(el, 'app-sidebar');
+
+    if (!sidebar) throw new Error('no sidebar');
+
+    expect(getComputedStyle(sidebar).backgroundColor).toBe('rgba(0, 0, 0, 0)');
+  });
+
+  it('gives the sheet the whole width, which the sidebar does not take', async () => {
+    const el = await fixture<Nav>('bottom-nav');
+
+    shadow<HTMLButtonElement>(el, '[data-testid="tab-more"]')?.click();
+    await update(el, {});
+
+    const sidebar = shadow<HTMLElement>(el, 'app-sidebar');
+
+    if (!sidebar) throw new Error('no sidebar');
+
+    // `app-sidebar` writes an *inline* width and caps itself at 400px,
+    // which beats any rule this host could write — so "the host owns
+    // the box" has to be part of what `expanded` means, or the sheet
+    // draws the old 200px column inside a full-width surface.
+    expect(sidebar.style.width).toBe('100%');
+    expect(getComputedStyle(sidebar).maxWidth).toBe('none');
+  });
+
+  it('sizes the sheet rows for a thumb, below the phone breakpoint', async () => {
+    const el = await fixture<Nav>('bottom-nav');
+
+    shadow<HTMLButtonElement>(el, '[data-testid="tab-more"]')?.click();
+    await update(el, {});
+
+    const sidebar = shadow<HTMLElement>(el, 'app-sidebar');
+    const sheets = sidebar?.shadowRoot?.adoptedStyleSheets ?? [];
+    const phoneRules: string[] = [];
+
+    for (const sheet of sheets) {
+      for (const rule of Array.from(sheet.cssRules)) {
+        if (!(rule instanceof CSSMediaRule)) continue;
+
+        if (!/max-width:\s*599px/.test(rule.conditionText)) continue;
+
+        for (const inner of Array.from(rule.cssRules)) {
+          phoneRules.push(inner.cssText);
+        }
+      }
+    }
+
+    // Asserted against the parsed stylesheet, like
+    // `hover-affordance.test.ts` and for the same reason: this tier's
+    // iframe is not 599px wide, so the rule cannot be *rendered* here —
+    // but the regression worth catching is someone moving it out of the
+    // query, which nothing on a desktop draws differently.
+    expect(phoneRules.length).toBeGreaterThan(0);
+    expect(phoneRules.some((r) => /min-height:\s*48px/.test(r))).toBe(true);
+  });
+
+  it('takes the resize handle out of the sheet', async () => {
+    const el = await fixture<Nav>('bottom-nav');
+
+    shadow<HTMLButtonElement>(el, '[data-testid="tab-more"]')?.click();
+    await update(el, {});
+
+    const handle = shadow<HTMLElement>(el, 'app-sidebar')
+      ?.shadowRoot?.querySelector('.resize-handle');
+
+    if (!handle) throw new Error('no resize handle');
+
+    // A col-resize strip on the right edge of a touch surface: the
+    // compatibility mouse events a tap synthesises reach its
+    // `mousedown`, so it can start a resize nobody asked for.
+    expect(getComputedStyle(handle).display).toBe('none');
+  });
 });

frontend/test/components/chrome.test.ts

@@ -137,6 +137,11 @@ describe('<app-sidebar>', () => {
   });
 
   it('looks the way it did last time', async () => {
+    // Stated rather than inherited: `activeViewStore` is a singleton, so
+    // without this the shot records whichever view the *previous* case
+    // left in it and the reference moves when the file is reordered.
+    activeViewStore.setView('home', true);
+
     const el = await fixture('app-sidebar');
 
     await visual(el, 'app-sidebar');

frontend/test/components/long-press.test.ts

@@ -1,212 +0,0 @@
-/**
- * Long-press as the touch route to a context menu (plan 016 B2 phase 3).
- *
- * These run in a real browser with real event dispatch, which is the
- * only place the two things that make this hard are true: the synthetic
- * event has to cross a shadow boundary to reach the listener a
- * component actually bound, and the suppressors have to tell a trusted
- * event from ours at document capture without eating the one they exist
- * to deliver.
- *
- * The timings are real rather than faked, because the thing under test
- * *is* a timing, and 600 ms twice is cheaper than a fake-timer harness
- * that would also have to fake the pointer events.
- */
-import { describe, expect, it, afterEach, beforeEach } from 'vitest';
-
-import {
-  installLongPressContextMenu,
-  LONG_PRESS_MS,
-  MOVE_TOLERANCE_PX,
-} from '@utils/long-press';
-
-/** A press that has certainly resolved, either way. */
-const HELD = LONG_PRESS_MS + 120;
-
-/** A press that has certainly not. */
-const BRIEF = Math.round(LONG_PRESS_MS / 4);
-
-const wait = (ms: number) => new Promise((r) => setTimeout(r, ms));
-
-let uninstall: (() => void) | null = null;
-let host: HTMLElement;
-let inner: HTMLElement;
-
-/** A row inside a shadow root, which is where every menu in this app
- *  is bound — an element in the light DOM would pass a weaker test. */
-function mountRow(): { host: HTMLElement; inner: HTMLElement } {
-  const el = document.createElement('div');
-  const root = el.attachShadow({ mode: 'open' });
-  const row = document.createElement('div');
-
-  row.textContent = 'a track';
-  root.append(row);
-  document.body.append(el);
-
-  return { host: el, inner: row };
-}
-
-function press(
-  el: EventTarget,
-  type: string,
-  init: PointerEventInit = {},
-): void {
-  el.dispatchEvent(
-    new PointerEvent(type, {
-      bubbles: true,
-      composed: true,
-      cancelable: true,
-      pointerType: 'touch',
-      isPrimary: true,
-      clientX: 40,
-      clientY: 60,
-      ...init,
-    }),
-  );
-}
-
-/**
- * Record every `contextmenu` that reaches the listener, *as the
- * listener sees it*.
- *
- * `target` is retargeted for the scope reading it, so an assertion made
- * after dispatch has finished reports the shadow host however the event
- * was dispatched - which is the same answer a broken implementation
- * gives. It has to be read from inside the handler, where the component
- * reads it.
- */
-function recordMenus(el: EventTarget): { event: MouseEvent; target: EventTarget | null }[] {
-  const seen: { event: MouseEvent; target: EventTarget | null }[] = [];
-
-  el.addEventListener('contextmenu', (e) => {
-    e.preventDefault();
-    // Every real handler does this; the gesture must work anyway.
-    e.stopPropagation();
-    seen.push({ event: e as MouseEvent, target: e.target });
-  });
-
-  return seen;
-}
-
-describe('long-press opens a context menu', () => {
-  beforeEach(() => {
-    uninstall = installLongPressContextMenu();
-    ({ host, inner } = mountRow());
-  });
-
-  afterEach(() => {
-    uninstall?.();
-    uninstall = null;
-    host.remove();
-  });
-
-  it('dispatches one at the touch point, on the element touched', async () => {
-    const seen = recordMenus(inner);
-
-    press(inner, 'pointerdown');
-    await wait(HELD);
-
-    expect(seen).toHaveLength(1);
-    expect(seen[0]?.event.clientX).toBe(40);
-    expect(seen[0]?.event.clientY).toBe(60);
-    // Dispatched on the row itself, not on its shadow host - which is
-    // the difference between a per-row handler firing and only a
-    // delegated one firing.
-    expect(seen[0]?.target).toBe(inner);
-  });
-
-  it('is cancelled by a press that moves', async () => {
-    const seen = recordMenus(inner);
-
-    press(inner, 'pointerdown');
-    press(inner, 'pointermove', {
-      clientX: 40 + MOVE_TOLERANCE_PX + 5,
-      clientY: 60,
-    });
-    await wait(HELD);
-
-    expect(seen).toHaveLength(0);
-  });
-
-  it('tolerates the jitter a finger cannot help', async () => {
-    const seen = recordMenus(inner);
-
-    press(inner, 'pointerdown');
-    press(inner, 'pointermove', { clientX: 43, clientY: 62 });
-    await wait(HELD);
-
-    expect(seen).toHaveLength(1);
-  });
-
-  it('is cancelled by lifting early, and by a scroll', async () => {
-    const seen = recordMenus(inner);
-
-    press(inner, 'pointerdown');
-    await wait(BRIEF);
-    press(inner, 'pointerup');
-    await wait(HELD);
-
-    expect(seen).toHaveLength(0);
-
-    press(inner, 'pointerdown');
-    press(inner, 'pointercancel');
-    await wait(HELD);
-
-    expect(seen).toHaveLength(0);
-  });
-
-  it('ignores a mouse, which has a right button of its own', async () => {
-    const seen = recordMenus(inner);
-
-    press(inner, 'pointerdown', { pointerType: 'mouse' });
-    await wait(HELD);
-
-    expect(seen).toHaveLength(0);
-  });
-
-  it('swallows the click that ends the gesture, and only that one', async () => {
-    let clicks = 0;
-
-    inner.addEventListener('click', () => {
-      clicks += 1;
-    });
-
-    press(inner, 'pointerdown');
-    await wait(HELD);
-    press(inner, 'pointerup');
-    inner.click();
-
-    expect(clicks).toBe(0);
-
-    // The next tap is a tap: on a phone that is the user choosing an
-    // item in the menu that just opened, so eating it would make the
-    // gesture useless.
-    press(inner, 'pointerdown');
-    press(inner, 'pointerup');
-    inner.click();
-
-    expect(clicks).toBe(1);
-  });
-
-  it('stands down where the browser fires its own', async () => {
-    const seen = recordMenus(inner);
-
-    press(inner, 'pointerdown');
-    await wait(BRIEF);
-    // Chromium does this itself on touch; WebKit and the Android
-    // WebView vary, which is the whole reason both halves exist. A
-    // test cannot dispatch a *trusted* event, which is why the module
-    // tells its own apart by identity rather than by `isTrusted`.
-    inner.dispatchEvent(
-      new MouseEvent('contextmenu', {
-        bubbles: true,
-        composed: true,
-        cancelable: true,
-      }),
-    );
-    await wait(HELD);
-
-    // One menu: the browser's. Not two.
-    expect(seen).toHaveLength(1);
-  });
-});

frontend/test/components/menu-surface.test.ts

@@ -206,6 +206,65 @@ describe('menu-surface', () => {
       expect(dismissed, 'no menu-dismiss reached the document').toBe(1);
     });
 
+    /**
+     * The scroll affordance (#207), and this is the mechanism again
+     * rather than the symptom.
+     *
+     * The sheet's body has scrolled since #60 and said nothing about
+     * it: measured at 424x439, eight items ended at y=470 with the
+     * fold at 439, and where the cut lands on a row boundary the sheet
+     * ends in a clean edge that reads as the end of the list.
+     *
+     * What makes the fade *conditional* — absent on a menu that fits,
+     * present the moment one does not, gone again at the end of the
+     * list — is `background-attachment`, not a scroll listener: a cover
+     * of the sheet's own colour is painted at the end of the content
+     * and attached `local`, over a shadow pinned to the box and
+     * attached `scroll`. So the pair of attachments *is* the feature,
+     * and it is what this asserts. The rendered result was measured in
+     * the harness (dark ramp 52,58,64 flat before; 52,57,63 at the last
+     * label and 22,24,27 at the bottom edge with more below; flat again
+     * at the end of the list) and is on the PR.
+     */
+    it('paints the fade only while there is more below', async () => {
+      const el = await surfaceWithPanel();
+
+      const wrapper = el.shadowRoot?.querySelector('wa-dialog');
+
+      await (wrapper as HTMLElement & { updateComplete: Promise<unknown> })
+        .updateComplete;
+
+      const body = wrapper?.shadowRoot?.querySelector('[part~="body"]');
+
+      expect(body, 'no body part to scroll').not.toBeNull();
+
+      const style = getComputedStyle(body as Element);
+
+      expect(style.overflowY, 'the body is what gives, not the cap').toBe(
+        'auto',
+      );
+
+      // The cover scrolls with the content; the shadow does not. Either
+      // one alone is a fade that is always there or never there.
+      expect(
+        style.backgroundAttachment,
+        'the cover must be local and the shadow must not',
+      ).toBe('local, scroll');
+
+      // Both sit at the bottom, or the cover hides nothing.
+      expect(style.backgroundPosition).toBe('50% 100%, 50% 100%');
+      expect(style.backgroundSize).toBe('100% 32px, 100% 32px');
+
+      // The layers are shared with `bottom-nav`'s sheet since #210, and
+      // the colour is what each host still says for itself: this one
+      // paints the menus' `--yj-bg-elevated` (#343a40). A shared rule
+      // that hard-coded one grey would draw a seam across the other
+      // sheet, which is why the fragment reads a custom property.
+      expect(style.backgroundImage).toMatch(
+        /^linear-gradient\(rgb\(52, 58, 64\), rgb\(52, 58, 64\)\)/,
+      );
+    });
+
     /**
      * A dialog with no accessible name is what `utils/name-dialog.ts`
      * exists for; here the name is already written on the panel, so no

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

@@ -366,6 +366,16 @@ describe('<now-playing>', () => {
     const el = await fixture('now-playing');
 
     emit(Events.TrackChanged, { ...TRACK, trackChangeId: 6 });
+    // Stated rather than inherited: the queue store is a singleton, so
+    // without this the shot records whichever source the *previous*
+    // case left in it and the reference moves when the file is
+    // reordered. Three lines is what the bar renders while playing
+    // from somewhere, which is the arrangement worth recording.
+    setQueue([queueTrack(1, 'Ashes to Ashes')], 0, {
+      type: 'album',
+      id: 7,
+      label: 'Scary Monsters',
+    });
     await flush();
     await el.updateComplete;
 

frontend/test/components/phone-entity-links.test.ts

@@ -0,0 +1,275 @@
+/**
+ * A name is not a link on a phone, and the menu is where it went (#67).
+ *
+ * `utils/explore-link.ts` makes every track, album and artist name
+ * navigable, with click handling that is explicitly a desktop
+ * compromise — the navigation is held for one double-click interval so
+ * double-clicking the row can still play it. On touch that is a delay
+ * on an ambiguous target, and since #63 the row's own tap claims the
+ * click anyway, so the link was unreachable as well as fiddly.
+ *
+ * So below the phone breakpoint a name renders as plain text and the
+ * row's context menu carries "Go to Artist" / "Go to Album" instead.
+ * The two halves are asserted together on purpose: a suppressed link
+ * with no menu item behind it is not a smaller affordance, it is a
+ * destination that cannot be reached, which is what plan 018 promises
+ * against.
+ *
+ * The breakpoint is stubbed rather than emulated for the reason
+ * `now-playing-phone.test.ts` states: this tier's viewport is fixed at
+ * 1280x800 by the runner, and `matchMedia` is the seam.
+ */
+import { describe, expect, it, beforeEach, afterEach } from 'vitest';
+import { html, render } from 'lit';
+import type { LitElement } from 'lit';
+
+import '@components/playlist-details/playlist-details';
+import {
+  albumLink,
+  artistLink,
+  creditLink,
+  trackLink,
+} from '@utils/explore-link';
+import { goToMenuItems } from '@utils/go-to-menu';
+import { stub, flush, resetHarness } from '@test/support/harness';
+import { fixture, shadowAll } from '@test/support/render';
+
+/** Answer the phone breakpoint, and hand back the undo. */
+function atPhone(phone: boolean): () => void {
+  const real = window.matchMedia.bind(window);
+
+  window.matchMedia = ((q: string) =>
+    q.includes('max-width: 599px')
+      ? {
+          matches: phone,
+          media: q,
+          addEventListener() {},
+          removeEventListener() {},
+        }
+      : real(q)) as typeof window.matchMedia;
+
+  return () => {
+    window.matchMedia = real as typeof window.matchMedia;
+  };
+}
+
+/** Render a template into a detached container and hand it back. */
+function draw(template: unknown): HTMLElement {
+  const host = document.createElement('div');
+
+  document.body.append(host);
+  render(html`${template}`, host);
+
+  return host;
+}
+
+describe('an inline name below the phone breakpoint', () => {
+  let restore: () => void = () => {};
+
+  afterEach(() => {
+    restore();
+    document.querySelectorAll('body > div').forEach((el) => el.remove());
+  });
+
+  it('is a link on a desktop', () => {
+    restore = atPhone(false);
+
+    const host = draw(artistLink('Cocteau Twins', 'artist-mbid'));
+
+    expect(host.querySelector('a.explore-link')).not.toBeNull();
+    expect(host.textContent?.trim()).toBe('Cocteau Twins');
+  });
+
+  it('is plain text on a phone, for all four shapes', () => {
+    restore = atPhone(true);
+
+    const host = draw(html`
+      ${artistLink('Cocteau Twins', 'artist-mbid')}
+      ${albumLink('Heaven or Las Vegas', 'rg-mbid')}
+      ${trackLink('Iceblink Luck', 'Heaven or Las Vegas', 'rg-mbid', 'rec-mbid')}
+      ${creditLink(
+        [
+          {
+            creditedName: 'Skrillex',
+            artistMbid: 'a1',
+            joinPhrase: ' feat. ',
+          },
+          { creditedName: 'Swae Lee', artistMbid: 'a2', joinPhrase: '' },
+        ],
+        'Skrillex & Swae Lee',
+        'a1',
+      )}
+    `);
+
+    expect(host.querySelectorAll('a.explore-link')).toHaveLength(0);
+
+    // The words survive, join phrases included — a decomposed credit is
+    // still assembled from its parts, so the text does not change with
+    // the affordance.
+    expect(host.textContent).toContain('Cocteau Twins');
+    expect(host.textContent).toContain('Heaven or Las Vegas');
+    expect(host.textContent).toContain('Iceblink Luck');
+    expect(host.textContent).toContain('Skrillex feat. Swae Lee');
+  });
+
+  it('stays a link where the caller has no menu to carry it', () => {
+    restore = atPhone(true);
+
+    const host = draw(
+      albumLink('Heaven or Las Vegas', 'rg-mbid', undefined, 'Cocteau Twins', {
+        keepOnPhone: true,
+      }),
+    );
+
+    expect(host.querySelector('a.explore-link')).not.toBeNull();
+  });
+});
+
+describe('the "Go to" menu items', () => {
+  let restore: () => void = () => {};
+
+  afterEach(() => {
+    restore();
+    document.querySelectorAll('body > div').forEach((el) => el.remove());
+  });
+
+  it('are absent on a desktop, where the name beside them is a link', () => {
+    restore = atPhone(false);
+
+    const host = draw(
+      goToMenuItems({ artistName: 'Cocteau Twins', albumName: 'Treasure' }),
+    );
+
+    expect(host.querySelectorAll('wa-dropdown-item')).toHaveLength(0);
+  });
+
+  it('offer only what the target knows', () => {
+    restore = atPhone(true);
+
+    const both = draw(
+      goToMenuItems({ artistName: 'Cocteau Twins', albumName: 'Treasure' }),
+    );
+    const artistOnly = draw(goToMenuItems({ artistName: 'Cocteau Twins' }));
+    const neither = draw(goToMenuItems({}));
+
+    expect(both.querySelectorAll('wa-dropdown-item')).toHaveLength(2);
+    expect(artistOnly.querySelectorAll('wa-dropdown-item')).toHaveLength(1);
+    expect(neither.querySelectorAll('wa-dropdown-item')).toHaveLength(0);
+  });
+});
+
+// =====================================================================
+// The menu that carries the destination
+// =====================================================================
+
+function playlistTracks(n: number) {
+  return Array.from({ length: n }, (_, i) => ({
+    ID: i + 1,
+    FilePath: `/music/track-${i}.mp3`,
+    Title: `Track ${i}`,
+    Artist: 'Cocteau Twins',
+    ArtistMBID: 'artist-mbid',
+    Album: 'Heaven or Las Vegas',
+    ReleaseGroupMBID: 'rg-mbid',
+    Duration: 180000,
+    Phantom: false,
+  }));
+}
+
+describe('a playlist row’s context menu on a phone', () => {
+  let el: LitElement;
+  let restore: () => void = () => {};
+
+  beforeEach(async () => {
+    resetHarness();
+    restore = atPhone(true);
+    stub('playlist.Service.GetPlaylistTracks', playlistTracks(8));
+    stub('playlist.Service.GetAllPlaylists', []);
+
+    el = await fixture<LitElement>('playlist-details', {
+      playlistId: 1,
+      playlistName: 'A playlist',
+    });
+    el.style.display = 'block';
+    el.style.height = '600px';
+    await flush();
+    await el.updateComplete;
+    await new Promise((r) => setTimeout(r, 60));
+  });
+
+  afterEach(() => {
+    restore();
+  });
+
+  /** Right-click a row and hand back the menu's items. */
+  async function openMenu(index: number): Promise<HTMLElement[]> {
+    const row = shadowAll(el, '.track-item').find(
+      (r) => r.getAttribute('data-index') === String(index),
+    );
+
+    row!.dispatchEvent(
+      new MouseEvent('contextmenu', { bubbles: true, composed: true }),
+    );
+    await el.updateComplete;
+
+    return shadowAll<HTMLElement>(el, 'wa-dropdown-item');
+  }
+
+  it('carries the artist and the album the row stopped linking to', async () => {
+    const labels = (await openMenu(3)).map((i) => i.textContent?.trim());
+
+    expect(labels).toContain('Go to Artist');
+    expect(labels).toContain('Go to Album');
+  });
+
+  it('navigates where the name would have', async () => {
+    const seen: CustomEvent[] = [];
+    const listen = (e: Event) => seen.push(e as CustomEvent);
+
+    document.addEventListener('navigate', listen);
+
+    try {
+      const items = await openMenu(3);
+
+      items
+        .find((i) => i.textContent?.trim() === 'Go to Artist')!
+        .click();
+      await flush();
+    } finally {
+      document.removeEventListener('navigate', listen);
+    }
+
+    expect(seen.map((e) => e.detail)).toEqual([
+      {
+        view: 'explore-artist-details',
+        artistMBID: 'artist-mbid',
+        artistName: 'Cocteau Twins',
+      },
+    ]);
+  });
+
+  it('is absent while several rows are selected', async () => {
+    // "Go to the album" of five different albums means nothing, which
+    // is the rule the Play item already follows: one row is a
+    // position, several are an explicit choice of those tracks.
+    const rows = shadowAll(el, '.track-item');
+    const click = (i: number, modifiers: MouseEventInit) =>
+      rows
+        .find((r) => r.getAttribute('data-index') === String(i))!
+        .dispatchEvent(
+          new MouseEvent('click', {
+            bubbles: true,
+            composed: true,
+            ...modifiers,
+          }),
+        );
+
+    click(1, {});
+    click(4, { ctrlKey: true });
+    await el.updateComplete;
+
+    const labels = (await openMenu(4)).map((i) => i.textContent?.trim());
+
+    expect(labels).not.toContain('Go to Artist');
+  });
+});

frontend/test/components/play-in-context.test.ts

@@ -161,6 +161,15 @@ describe('double-clicking a row in the track list', () => {
     localStorage.removeItem('track-list-column-widths');
 
     el = await fixture<LitElement>('track-list', { externalTracks: LIST });
+
+    // Say which order is being asserted rather than inheriting one.
+    // `restoreSortPreferences()` runs in `connectedCallback`, so the
+    // list opens in whatever sort was last persisted -- and
+    // `track-11` sorts before `track-3` by title, which is the shape
+    // of #138. The row below is the fixture's third track only while
+    // nothing is sorting the list.
+    (el as unknown as { sortField: string | null }).sortField = null;
+
     el.style.display = 'block';
     el.style.height = '600px';
     await flush();
@@ -172,6 +181,10 @@ describe('double-clicking a row in the track list', () => {
     const rows = shadowAll(el, '.track-row');
     const row = rows.find((r) => r.getAttribute('data-index') === '3');
 
+    // Stated first, so a list that is not in the order this asserts
+    // fails by saying so rather than as an off-by-eight file path.
+    expect(row?.getAttribute('data-file-path')).toBe('/music/track-3.mp3');
+
     dblclick(row!);
     await flush();
 

frontend/test/components/press-feedback.test.ts

@@ -0,0 +1,191 @@
+/**
+ * What a tap looks like now that the web view's own highlight is gone
+ * (#54).
+ *
+ * `index.css` sets `-webkit-tap-highlight-color: transparent` on
+ * `html`, which — the property being inherited — reaches every shadow
+ * root in the app. That takes away the grey box a phone drew over the
+ * bounding rect of whatever was tapped, and with it the only touch
+ * feedback the rows, the tab bar, the sidebar's destinations and the
+ * shared menu items had. So the press states below are not decoration:
+ * without them this change trades wrong feedback for none.
+ *
+ * **Asserted against the parsed stylesheet**, on `hover-affordance`'s
+ * precedent and with the same limitation stated out loud: CDP's
+ * `Emulation.setEmulatedMedia` does not reach this tier's iframe, so
+ * there is no way here to render a component as a phone would, and
+ * `:active` cannot be forced from a test either. What the browser will
+ * answer is the shape it built from the `css` literal — which rule sits
+ * inside which media query, and what the press selector actually is.
+ *
+ * Two regressions are worth catching that way, and both are silent on a
+ * desktop:
+ *
+ * - someone hoisting a hover tint back out of its query as a tidy-up,
+ *   which on a phone is a highlight that arrives because a finger
+ *   touched the row and stays after it has gone;
+ * - someone simplifying the press selector to a bare `:active`, which
+ *   is one class short of `.selected` / `.active` and so does nothing
+ *   on the row a phone is most likely to press — the one it has just
+ *   selected.
+ *
+ * The pixels are the Android tier's, and the tap highlight itself is
+ * `e2e/specs/native-touch-feel.spec.ts`, since only the real app loads
+ * `index.css` at all.
+ */
+import { describe, expect, it } from 'vitest';
+
+import '@components/track-list/track-list';
+import '@components/queue-panel/queue-panel';
+import '@components/playlist-details/playlist-details';
+import '@components/smart-playlist-details/smart-playlist-details';
+import '@components/bottom-nav/bottom-nav';
+import '@components/sidebar/app-sidebar';
+import { fixture } from '@test/support/render';
+
+/** Every rule in the element's own adopted stylesheets, flattened. */
+function rulesOf(host: Element): { text: string; condition: string | null }[] {
+  const sheets = host.shadowRoot?.adoptedStyleSheets ?? [];
+  const out: { text: string; condition: string | null }[] = [];
+
+  for (const sheet of sheets) {
+    for (const rule of Array.from(sheet.cssRules)) {
+      if (rule instanceof CSSMediaRule) {
+        for (const inner of Array.from(rule.cssRules)) {
+          out.push({ text: inner.cssText, condition: rule.conditionText });
+        }
+
+        continue;
+      }
+
+      out.push({ text: rule.cssText, condition: null });
+    }
+  }
+
+  return out;
+}
+
+/** The four lists, their row selector, and the tag that draws them. */
+const LISTS: Array<[string, string]> = [
+  ['track-list', '.track-row'],
+  ['queue-panel', '.track-item'],
+  ['playlist-details', '.track-item'],
+  ['smart-playlist-details', '.track-item'],
+];
+
+describe('a row says it is being pressed', () => {
+  for (const [tag, row] of LISTS) {
+    it(`${tag} draws a press state that survives its state classes`, async () => {
+      const el = await fixture(tag, {});
+      const rules = rulesOf(el);
+
+      // Worth nothing if it read no rules at all — the first assertion
+      // icon-language.test.ts makes, for the same reason.
+      expect(rules.length).toBeGreaterThan(0);
+
+      const press = rules.filter(
+        (r) => r.text.includes(`${row}:active`) && r.text.includes('background-color'),
+      );
+
+      expect(press.length).toBeGreaterThan(0);
+
+      for (const rule of press) {
+        // A press is not a hover: it is the one thing a touch device
+        // can say, so it must not sit behind a pointer query.
+        expect(rule.condition).toBeNull();
+        expect(rule.text).toContain('--yj-press-overlay');
+      }
+
+      // The load-bearing half: the selector carries a state class, or
+      // it loses to `.selected` / `.selected.active` and the press is
+      // invisible on a selected or playing row.
+      expect(press.some((r) => r.text.includes(`${row}.selected:active`))).toBe(true);
+    });
+
+    it(`${tag} keeps its hover tint for devices that hover`, async () => {
+      const el = await fixture(tag, {});
+      const rules = rulesOf(el);
+
+      expect(rules.length).toBeGreaterThan(0);
+
+      const hover = rules.filter(
+        (r) =>
+          r.text.includes(`${row}:hover`) &&
+          r.text.includes('--yj-hover-overlay'),
+      );
+
+      expect(hover.length).toBeGreaterThan(0);
+
+      for (const rule of hover) {
+        expect(rule.condition).toMatch(/hover:\s*hover/);
+        expect(rule.condition).toMatch(/pointer:\s*fine/);
+      }
+    });
+  }
+});
+
+describe('the two navigations say they are being pressed', () => {
+  it('the phone tab bar, which had no state of its own at all', async () => {
+    const el = await fixture('bottom-nav', {});
+    const rules = rulesOf(el);
+
+    expect(rules.length).toBeGreaterThan(0);
+
+    const press = rules.filter((r) => r.text.startsWith('button:active'));
+
+    expect(press.length).toBe(1);
+    expect(press[0]!.condition).toBeNull();
+    expect(press[0]!.text).toContain('--yj-press-overlay');
+  });
+
+  it("the sidebar, which is also the phone's More sheet", async () => {
+    const el = await fixture('app-sidebar', {});
+    const rules = rulesOf(el);
+
+    expect(rules.length).toBeGreaterThan(0);
+
+    const press = rules.filter((r) => r.text.startsWith('li button:active'));
+
+    expect(press.length).toBe(1);
+    expect(press[0]!.condition).toBeNull();
+    expect(press[0]!.text).toContain('--yj-press-overlay');
+
+    // Its hover tint is a destination looking picked, if it is left to
+    // a synthesised hover inside the More sheet.
+    const hover = rules.filter((r) => r.text.startsWith('li button:hover'));
+
+    expect(hover.length).toBeGreaterThan(0);
+
+    for (const rule of hover) {
+      expect(rule.condition).toMatch(/hover:\s*hover/);
+    }
+  });
+});
+
+describe('the shared context menu', () => {
+  // One stylesheet, fourteen menus — the same reason the sheet's row
+  // height lives there rather than in each host.
+  it('presses its items, in the one place every menu includes', async () => {
+    const el = await fixture('queue-panel', {});
+    const rules = rulesOf(el);
+
+    const press = rules.filter((r) =>
+      r.text.startsWith('.context-menu-panel wa-dropdown-item:active'),
+    );
+
+    expect(press.length).toBe(1);
+    expect(press[0]!.condition).toBeNull();
+    expect(press[0]!.text).toContain('--yj-press-overlay');
+
+    const hover = rules.filter((r) =>
+      r.text.startsWith('.context-menu-panel wa-dropdown-item:hover'),
+    );
+
+    expect(hover.length).toBeGreaterThan(0);
+
+    for (const rule of hover) {
+      expect(rule.condition).toMatch(/hover:\s*hover/);
+      expect(rule.condition).toMatch(/pointer:\s*fine/);
+    }
+  });
+});

frontend/test/components/touch-gestures.test.ts

@@ -0,0 +1,681 @@
+/**
+ * The touch gestures (plan 019, #63; long-press from plan 016 B2).
+ *
+ * These run in a real browser with real event dispatch, which is the
+ * only place the two things that make this hard are true: the synthetic
+ * event has to cross a shadow boundary to reach the listener a
+ * component actually bound, and the suppressors have to tell a trusted
+ * event from ours at document capture without eating the one they exist
+ * to deliver.
+ *
+ * The timings are real rather than faked, because the thing under test
+ * *is* a timing, and 600 ms twice is cheaper than a fake-timer harness
+ * that would also have to fake the pointer events.
+ */
+import { describe, expect, it, afterEach, beforeEach } from 'vitest';
+
+import {
+  installTouchGestures,
+  LONG_PRESS_MS,
+  MOVE_TOLERANCE_PX,
+} from '@utils/touch-gestures';
+
+/** A press that has certainly resolved, either way. */
+const HELD = LONG_PRESS_MS + 120;
+
+/** A press that has certainly not. */
+const BRIEF = Math.round(LONG_PRESS_MS / 4);
+
+const wait = (ms: number) => new Promise((r) => setTimeout(r, ms));
+
+let uninstall: (() => void) | null = null;
+let host: HTMLElement;
+let inner: HTMLElement;
+
+/** A row inside a shadow root, which is where every menu in this app
+ *  is bound — an element in the light DOM would pass a weaker test. */
+function mountRow(): { host: HTMLElement; inner: HTMLElement } {
+  const el = document.createElement('div');
+  const root = el.attachShadow({ mode: 'open' });
+  const row = document.createElement('div');
+
+  row.textContent = 'a track';
+  root.append(row);
+  document.body.append(el);
+
+  return { host: el, inner: row };
+}
+
+function press(
+  el: EventTarget,
+  type: string,
+  init: PointerEventInit = {},
+): void {
+  el.dispatchEvent(
+    new PointerEvent(type, {
+      bubbles: true,
+      composed: true,
+      cancelable: true,
+      pointerType: 'touch',
+      isPrimary: true,
+      clientX: 40,
+      clientY: 60,
+      ...init,
+    }),
+  );
+}
+
+/**
+ * Record every `contextmenu` that reaches the listener, *as the
+ * listener sees it*.
+ *
+ * `target` is retargeted for the scope reading it, so an assertion made
+ * after dispatch has finished reports the shadow host however the event
+ * was dispatched - which is the same answer a broken implementation
+ * gives. It has to be read from inside the handler, where the component
+ * reads it.
+ */
+function recordMenus(el: EventTarget): { event: MouseEvent; target: EventTarget | null }[] {
+  const seen: { event: MouseEvent; target: EventTarget | null }[] = [];
+
+  el.addEventListener('contextmenu', (e) => {
+    e.preventDefault();
+    // Every real handler does this; the gesture must work anyway.
+    e.stopPropagation();
+    seen.push({ event: e as MouseEvent, target: e.target });
+  });
+
+  return seen;
+}
+
+describe('an unclaimed long press is still a context menu', () => {
+  beforeEach(() => {
+    uninstall = installTouchGestures();
+    ({ host, inner } = mountRow());
+  });
+
+  afterEach(() => {
+    uninstall?.();
+    uninstall = null;
+    host.remove();
+  });
+
+  it('dispatches one at the touch point, on the element touched', async () => {
+    const seen = recordMenus(inner);
+
+    press(inner, 'pointerdown');
+    await wait(HELD);
+
+    expect(seen).toHaveLength(1);
+    expect(seen[0]?.event.clientX).toBe(40);
+    expect(seen[0]?.event.clientY).toBe(60);
+    // Dispatched on the row itself, not on its shadow host - which is
+    // the difference between a per-row handler firing and only a
+    // delegated one firing.
+    expect(seen[0]?.target).toBe(inner);
+  });
+
+  it('is cancelled by a press that moves', async () => {
+    const seen = recordMenus(inner);
+
+    press(inner, 'pointerdown');
+    press(inner, 'pointermove', {
+      clientX: 40 + MOVE_TOLERANCE_PX + 5,
+      clientY: 60,
+    });
+    await wait(HELD);
+
+    expect(seen).toHaveLength(0);
+  });
+
+  it('tolerates the jitter a finger cannot help', async () => {
+    const seen = recordMenus(inner);
+
+    press(inner, 'pointerdown');
+    press(inner, 'pointermove', { clientX: 43, clientY: 62 });
+    await wait(HELD);
+
+    expect(seen).toHaveLength(1);
+  });
+
+  it('is cancelled by lifting early, and by a scroll', async () => {
+    const seen = recordMenus(inner);
+
+    press(inner, 'pointerdown');
+    await wait(BRIEF);
+    press(inner, 'pointerup');
+    await wait(HELD);
+
+    expect(seen).toHaveLength(0);
+
+    press(inner, 'pointerdown');
+    press(inner, 'pointercancel');
+    await wait(HELD);
+
+    expect(seen).toHaveLength(0);
+  });
+
+  it('ignores a mouse, which has a right button of its own', async () => {
+    const seen = recordMenus(inner);
+
+    press(inner, 'pointerdown', { pointerType: 'mouse' });
+    await wait(HELD);
+
+    expect(seen).toHaveLength(0);
+  });
+
+  it('swallows the click that ends the gesture, and only that one', async () => {
+    let clicks = 0;
+
+    inner.addEventListener('click', () => {
+      clicks += 1;
+    });
+
+    press(inner, 'pointerdown');
+    await wait(HELD);
+    press(inner, 'pointerup');
+    inner.click();
+
+    expect(clicks).toBe(0);
+
+    // The next tap is a tap: on a phone that is the user choosing an
+    // item in the menu that just opened, so eating it would make the
+    // gesture useless.
+    press(inner, 'pointerdown');
+    press(inner, 'pointerup');
+    inner.click();
+
+    expect(clicks).toBe(1);
+  });
+
+  it('stands down where the browser fires its own', async () => {
+    const seen = recordMenus(inner);
+
+    press(inner, 'pointerdown');
+    await wait(BRIEF);
+    // Chromium does this itself on touch; WebKit and the Android
+    // WebView vary, which is the whole reason both halves exist. A
+    // test cannot dispatch a *trusted* event, which is why the module
+    // tells its own apart by identity rather than by `isTrusted`.
+    inner.dispatchEvent(
+      new MouseEvent('contextmenu', {
+        bubbles: true,
+        composed: true,
+        cancelable: true,
+      }),
+    );
+    await wait(HELD);
+
+    // One menu: the browser's. Not two.
+    expect(seen).toHaveLength(1);
+  });
+});
+
+/**
+ * What plan 019 adds on top, and the one property that protects
+ * everything downstream: a long press nobody claims is unchanged.
+ */
+describe('a gesture is announced before it is acted on', () => {
+  beforeEach(() => {
+    uninstall = installTouchGestures();
+    ({ host, inner } = mountRow());
+  });
+
+  afterEach(() => {
+    uninstall?.();
+    uninstall = null;
+    host.remove();
+  });
+
+  it('does not synthesise a menu when the long press is claimed', async () => {
+    // This is the whole reason #63 could reassign the hold without
+    // touching one of the fourteen context menus: the lists that want
+    // selection mode claim it, and nothing else changes.
+    const menus = recordMenus(inner);
+    const presses: unknown[] = [];
+
+    inner.addEventListener('yj-long-press', (e) => {
+      presses.push(e);
+      e.preventDefault();
+    });
+
+    press(inner, 'pointerdown');
+    await wait(HELD);
+
+    expect(presses).toHaveLength(1);
+    expect(menus).toHaveLength(0);
+  });
+
+  it('announces a tap on the element touched, at the touch point', async () => {
+    const taps: { target: EventTarget | null; x: number; y: number }[] = [];
+
+    inner.addEventListener('yj-tap', (e) => {
+      taps.push({ target: e.target, x: e.detail.x, y: e.detail.y });
+    });
+
+    press(inner, 'pointerdown');
+    await wait(BRIEF);
+    press(inner, 'pointerup');
+
+    expect(taps).toHaveLength(1);
+    // The row, not its shadow host -- the difference between a
+    // delegated handler firing and a per-row one never firing.
+    expect(taps[0]?.target).toBe(inner);
+    expect([taps[0]?.x, taps[0]?.y]).toEqual([40, 60]);
+  });
+
+  it('lets an unclaimed tap through as an ordinary click', async () => {
+    // Every button, link and checkbox in the app depends on this. Only
+    // a *claimed* tap has its click swallowed.
+    let clicks = 0;
+
+    inner.addEventListener('yj-tap', () => {
+      /* seen, not claimed */
+    });
+    inner.addEventListener('click', () => {
+      clicks += 1;
+    });
+
+    press(inner, 'pointerdown');
+    await wait(BRIEF);
+    press(inner, 'pointerup');
+    inner.click();
+
+    expect(clicks).toBe(1);
+  });
+
+  it('swallows the click behind a claimed tap', async () => {
+    // Or playing a track would also select it, and the row would end
+    // up in both states at once.
+    let clicks = 0;
+
+    inner.addEventListener('yj-tap', (e) => e.preventDefault());
+    inner.addEventListener('click', () => {
+      clicks += 1;
+    });
+
+    press(inner, 'pointerdown');
+    await wait(BRIEF);
+    press(inner, 'pointerup');
+    inner.click();
+
+    expect(clicks).toBe(0);
+  });
+
+  it('does not announce a tap for a press that became a long press', async () => {
+    // A hold is one gesture, not a hold and then a tap on release.
+    const taps: unknown[] = [];
+
+    inner.addEventListener('yj-tap', (e) => taps.push(e));
+
+    press(inner, 'pointerdown');
+    await wait(HELD);
+    press(inner, 'pointerup');
+
+    expect(taps).toHaveLength(0);
+  });
+
+  it('does not announce a tap for a press that drifted', async () => {
+    // A drifted press is a scroll, and the virtualizer's -- not a tap
+    // that happened to move. This is the one that would make a list
+    // unscrollable if it were wrong.
+    const taps: unknown[] = [];
+
+    inner.addEventListener('yj-tap', (e) => taps.push(e));
+
+    press(inner, 'pointerdown');
+    press(inner, 'pointermove', {
+      clientX: 40,
+      clientY: 60 + MOVE_TOLERANCE_PX + 20,
+    });
+    press(inner, 'pointerup');
+
+    expect(taps).toHaveLength(0);
+  });
+
+  it('ignores a mouse entirely, for both gestures', async () => {
+    // plan 019 decision 1: the predicate is the pointer, per event. A
+    // mouse on a touchscreen keeps click-selects / double-click-plays
+    // on the very same row, which no viewport width can express.
+    const seen: unknown[] = [];
+
+    inner.addEventListener('yj-tap', (e) => seen.push(e));
+    inner.addEventListener('yj-long-press', (e) => seen.push(e));
+
+    press(inner, 'pointerdown', { pointerType: 'mouse' });
+    await wait(BRIEF);
+    press(inner, 'pointerup', { pointerType: 'mouse' });
+    press(inner, 'pointerdown', { pointerType: 'mouse' });
+    await wait(HELD);
+
+    expect(seen).toHaveLength(0);
+  });
+});
+
+/**
+ * The browser's own long press is a trigger, not a competitor.
+ *
+ * This is a device-only defect made checkable here. `long-press.ts`
+ * stood down when a trusted `contextmenu` arrived mid-press, which was
+ * right while both paths ended in a context menu. Once a hold can mean
+ * *selection mode*, standing down means the gesture silently does the
+ * old thing — and Chrome 113's Android WebView does fire its own, so
+ * on the reference device `yj-long-press` was never announced at all
+ * while every test in this tier passed.
+ *
+ * A test cannot dispatch a *trusted* event, which is exactly why the
+ * module tells its own apart by identity rather than by `isTrusted`:
+ * an untrusted one dispatched from here takes the same path the
+ * browser's does.
+ */
+describe("the browser's own long press", () => {
+  beforeEach(() => {
+    uninstall = installTouchGestures();
+    ({ host, inner } = mountRow());
+  });
+
+  afterEach(() => {
+    uninstall?.();
+    uninstall = null;
+    host.remove();
+  });
+
+  /** Stand in for the browser recognising the hold itself. */
+  function browserContextMenu(el: EventTarget): MouseEvent {
+    const e = new MouseEvent('contextmenu', {
+      bubbles: true,
+      composed: true,
+      cancelable: true,
+    });
+
+    el.dispatchEvent(e);
+
+    return e;
+  }
+
+  it('announces the gesture rather than standing down', async () => {
+    const presses: unknown[] = [];
+
+    inner.addEventListener('yj-long-press', (e) => {
+      presses.push(e);
+      e.preventDefault();
+    });
+
+    press(inner, 'pointerdown');
+    await wait(BRIEF);
+    browserContextMenu(inner);
+    await wait(HELD);
+
+    expect(presses, 'the hold reached the component').toHaveLength(1);
+  });
+
+  it('suppresses its menu when a component claims the gesture', async () => {
+    const menus = recordMenus(inner);
+
+    inner.addEventListener('yj-long-press', (e) => e.preventDefault());
+
+    press(inner, 'pointerdown');
+    await wait(BRIEF);
+    browserContextMenu(inner);
+    await wait(HELD);
+
+    // The component wants selection mode, so the menu must not also
+    // open -- otherwise the device shows both at once.
+    expect(menus).toHaveLength(0);
+  });
+
+  it('suppresses a menu that arrives after the hold was claimed', async () => {
+    // The order the device actually produces, and the one that was
+    // missing: our 500ms timer fires first and a component claims it,
+    // then Chrome delivers its own `contextmenu` 50-70ms later.
+    // Measured over four holds on the reference phone, two took this
+    // order -- so the context menu opened over the selection bar,
+    // intermittently, on the one surface #63 changed.
+    const menus = recordMenus(inner);
+
+    inner.addEventListener('yj-long-press', (e) => e.preventDefault());
+
+    press(inner, 'pointerdown');
+    await wait(HELD);
+    browserContextMenu(inner);
+
+    expect(menus, 'the menu is late, not new').toHaveLength(0);
+  });
+
+  it('still opens exactly one menu when nobody claims it', async () => {
+    // The old behaviour, reached by asking instead of assuming. This
+    // is what leaves the card grids, Explore and the playlist rows
+    // untouched by #63.
+    const menus = recordMenus(inner);
+
+    press(inner, 'pointerdown');
+    await wait(BRIEF);
+    browserContextMenu(inner);
+    await wait(HELD);
+
+    expect(menus).toHaveLength(1);
+  });
+});
+
+/**
+ * The swipe half (plan 019 phase 2, #63).
+ *
+ * It runs on touch events rather than pointer events, and that is the
+ * one thing about it a browser tier cannot check. Measured on the
+ * reference device: Chrome 113's WebView cancels the *pointer* stream
+ * ~16px into any drag whatever `touch-action` says, while `touchmove`
+ * keeps firing — so what these assert is the shape that survives it,
+ * not that it survives.
+ *
+ * What they can hold is everything else: the axis rule, that the tie
+ * breaks toward the scroller, that an unclaimed swipe is left entirely
+ * alone, that a claimed one prevents the default (which is the half of
+ * the device fix that lives in code), and that an end always arrives.
+ */
+describe('a finger dragged sideways', () => {
+  beforeEach(() => {
+    uninstall = installTouchGestures();
+    ({ host, inner } = mountRow());
+  });
+
+  afterEach(() => {
+    uninstall?.();
+    uninstall = null;
+    host.remove();
+  });
+
+  /** One finger, at an offset from where it landed. */
+  function touch(el: EventTarget, type: string, dx = 0, dy = 0): TouchEvent {
+    const point = new Touch({
+      identifier: 1,
+      target: el as EventTarget as Element,
+      clientX: 40 + dx,
+      clientY: 60 + dy,
+    });
+    const event = new TouchEvent(type, {
+      bubbles: true,
+      composed: true,
+      cancelable: true,
+      touches: type === 'touchend' || type === 'touchcancel' ? [] : [point],
+      changedTouches: [point],
+    });
+
+    el.dispatchEvent(event);
+
+    return event;
+  }
+
+  /** Record the swipe events a component would bind. */
+  function recordSwipes(
+    el: EventTarget,
+    opts: { claim?: boolean } = {},
+  ): { type: string; dx: number; canceled: boolean }[] {
+    const seen: { type: string; dx: number; canceled: boolean }[] = [];
+
+    for (const name of ['yj-swipe-start', 'yj-swipe-move', 'yj-swipe-end']) {
+      el.addEventListener(name, (e) => {
+        const detail = (e as CustomEvent<{ dx: number; canceled: boolean }>)
+          .detail;
+
+        if (name === 'yj-swipe-start' && opts.claim !== false) {
+          e.preventDefault();
+        }
+
+        seen.push({ type: name, dx: detail.dx, canceled: detail.canceled });
+      });
+    }
+
+    return seen;
+  }
+
+  it('announces a swipe once it has travelled decisively sideways', () => {
+    const seen = recordSwipes(inner);
+
+    touch(inner, 'touchstart');
+    touch(inner, 'touchmove', 4);
+    expect(seen, 'a wobble is not a swipe').toHaveLength(0);
+
+    touch(inner, 'touchmove', 30);
+    touch(inner, 'touchmove', 60);
+    touch(inner, 'touchend');
+
+    expect(seen.map((s) => s.type)).toEqual([
+      'yj-swipe-start',
+      'yj-swipe-move',
+      'yj-swipe-end',
+    ]);
+    expect(seen.at(-1)?.dx).toBe(60);
+    expect(seen.at(-1)?.canceled).toBe(false);
+  });
+
+  it('prevents the default only for a claimed swipe', () => {
+    // This is the half of the device fix that lives in code: a
+    // non-passive `touchmove` calling `preventDefault` is what keeps
+    // the gesture ours on Chrome 113. Preventing anything else would
+    // be taking the list's scrolling away.
+    recordSwipes(inner);
+
+    touch(inner, 'touchstart');
+
+    const early = touch(inner, 'touchmove', 4);
+
+    expect(early.defaultPrevented, 'a wobble scrolls').toBe(false);
+
+    const claimed = touch(inner, 'touchmove', 30);
+    const after = touch(inner, 'touchmove', 60);
+
+    expect(claimed.defaultPrevented).toBe(true);
+    expect(after.defaultPrevented).toBe(true);
+  });
+
+  it('leaves an unclaimed swipe entirely alone', () => {
+    const seen = recordSwipes(inner, { claim: false });
+
+    touch(inner, 'touchstart');
+    touch(inner, 'touchmove', 30);
+
+    const later = touch(inner, 'touchmove', 60);
+
+    touch(inner, 'touchend');
+
+    // Asked once, refused, and then not asked again for the rest of
+    // the press -- and nothing prevented, so the browser still owns it.
+    expect(seen.map((s) => s.type)).toEqual(['yj-swipe-start']);
+    expect(later.defaultPrevented).toBe(false);
+  });
+
+  it('gives a drag that went vertical to the scroller, and keeps it', () => {
+    // The veto is a *latch*, and that is the whole of it: a scroll
+    // that curves — which is what a thumb does — would otherwise
+    // become a swipe halfway down the list, snatching the list out
+    // from under itself. Without the latch the second move here is
+    // decisively horizontal and would claim the gesture.
+    const seen = recordSwipes(inner);
+
+    touch(inner, 'touchstart');
+    touch(inner, 'touchmove', 4, 30);
+    touch(inner, 'touchmove', 80, 35);
+    touch(inner, 'touchend');
+
+    expect(seen, 'the list has it').toHaveLength(0);
+  });
+
+  it('gives the scroller the tie as well', () => {
+    // Exactly diagonal is not "decisively sideways". A list that will
+    // not scroll is unusable; a swipe that needs a second try is not.
+    const seen = recordSwipes(inner);
+
+    touch(inner, 'touchstart');
+    touch(inner, 'touchmove', 60, 60);
+    touch(inner, 'touchend');
+
+    expect(seen).toHaveLength(0);
+  });
+
+  it('is not a tap and not a hold once it is a swipe', async () => {
+    const menus = recordMenus(inner);
+    const taps: Event[] = [];
+
+    inner.addEventListener('yj-tap', (e) => taps.push(e));
+    recordSwipes(inner);
+
+    press(inner, 'pointerdown');
+    touch(inner, 'touchstart');
+    touch(inner, 'touchmove', 40);
+    await wait(HELD);
+    touch(inner, 'touchend');
+    press(inner, 'pointerup');
+
+    expect(menus, 'the hold did not become a menu').toHaveLength(0);
+    expect(taps, 'the lift did not become a tap').toHaveLength(0);
+  });
+
+  it('always ends, even when the gesture is taken away', () => {
+    // A component that has a row half off its own left edge has no
+    // other way to learn the finger is gone -- so `touchcancel` is an
+    // end with `canceled` set, not a silence.
+    const seen = recordSwipes(inner);
+
+    touch(inner, 'touchstart');
+    touch(inner, 'touchmove', 40);
+    touch(inner, 'touchcancel');
+
+    expect(seen.at(-1)?.type).toBe('yj-swipe-end');
+    expect(seen.at(-1)?.canceled).toBe(true);
+    expect(seen.at(-1)?.dx).toBe(40);
+  });
+
+  it('is never one gesture when there are two fingers', () => {
+    const seen = recordSwipes(inner);
+    const two = new TouchEvent('touchstart', {
+      bubbles: true,
+      composed: true,
+      cancelable: true,
+      touches: [
+        new Touch({ identifier: 1, target: inner, clientX: 40, clientY: 60 }),
+        new Touch({ identifier: 2, target: inner, clientX: 90, clientY: 60 }),
+      ],
+    });
+
+    inner.dispatchEvent(two);
+    touch(inner, 'touchmove', 60);
+
+    expect(seen, 'a pinch is not a swipe').toHaveLength(0);
+  });
+
+  it('swallows the click a claimed swipe ends on', () => {
+    const clicks: Event[] = [];
+
+    recordSwipes(inner);
+    inner.addEventListener('click', (e) => clicks.push(e));
+
+    touch(inner, 'touchstart');
+    touch(inner, 'touchmove', 40);
+    touch(inner, 'touchend');
+    inner.dispatchEvent(
+      new MouseEvent('click', { bubbles: true, composed: true }),
+    );
+
+    expect(clicks, 'the row was not also clicked').toHaveLength(0);
+  });
+});

frontend/test/components/touch-selection.test.ts

@@ -0,0 +1,396 @@
+/**
+ * What a finger does to a track list (plan 019, #63).
+ *
+ * The desktop semantics being diverged from are real and stay: a click
+ * selects, a double-click plays. A finger has no second button and no
+ * modifier keys, so the primary action has to be the primary gesture —
+ * and the inversion is decided **per event**, off `pointerType`, not
+ * off a viewport width or a platform flag (plan 019, decision 1).
+ *
+ * That is what these assert: the same row, in the same component, at
+ * the same width, answering a mouse one way and a finger the other.
+ *
+ * There is deliberately no double-tap. Measured on the reference
+ * device, playing a track is ~100ms end to end, and a double-tap
+ * discriminator has to hold every tap for the app's own
+ * `DOUBLE_CLICK_GRACE_MS` of 250 before it can act — 3.5x the primary
+ * interaction, to reach a menu a long press already reaches.
+ */
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+import '@components/track-list/track-list';
+import '@components/selection-bar/selection-bar';
+
+import { calls, flush, resetHarness, stub } from '@test/support/harness';
+import { fixture, shadow, shadowAll } from '@test/support/render';
+import { installTouchGestures, LONG_PRESS_MS } from '@utils/touch-gestures';
+
+const HELD = LONG_PRESS_MS + 120;
+
+/** Comfortably past `explore-link`'s own DOUBLE_CLICK_GRACE_MS of 250. */
+const EXPLORE_LINK_GRACE = 400;
+const BRIEF = Math.round(LONG_PRESS_MS / 4);
+const wait = (ms: number) => new Promise((r) => setTimeout(r, ms));
+
+let uninstall: (() => void) | null = null;
+
+function track(n: number) {
+  return {
+    FilePath: `/music/track-${n}.mp3`,
+    TrackName: `Track ${n}`,
+    ArtistName: 'An Artist',
+    Album: 'An Album',
+    Duration: 100 + n,
+    ID: n,
+    // Tagged, so the title's `explore-link` can actually navigate.
+    // Without an MBID it asks the backend for a local album first and
+    // gives up when nothing answers -- which makes "the tap did not
+    // navigate" true of every build, working or not.
+    ReleaseGroupMBID: 'e8f4b1d2-0000-4000-8000-00000000000' + n,
+    RecordingMBID: 'a1b2c3d4-0000-4000-8000-00000000000' + n,
+  };
+}
+
+const TRACKS = [track(1), track(2), track(3), track(4)];
+
+/** Dispatch a pointer event as a finger would produce it. */
+function press(el: EventTarget, type: string, init: PointerEventInit = {}) {
+  el.dispatchEvent(
+    new PointerEvent(type, {
+      bubbles: true,
+      composed: true,
+      cancelable: true,
+      pointerType: 'touch',
+      isPrimary: true,
+      clientX: 40,
+      clientY: 60,
+      ...init,
+    }),
+  );
+}
+
+/**
+ * A whole finger tap: down, a moment, up, and **the click a browser
+ * fires afterwards**.
+ *
+ * That last event is not decoration. A tap the component claims has
+ * its click swallowed at document capture, and the click is the only
+ * thing that would otherwise select the row, follow the `explore-link`
+ * in its title, or press whatever the finger landed on. A helper that
+ * stops at `pointerup` asserts none of that and passes on a build with
+ * the swallow deleted.
+ */
+async function tap(el: EventTarget) {
+  press(el, 'pointerdown');
+  await wait(BRIEF);
+  press(el, 'pointerup');
+  el.dispatchEvent(
+    new MouseEvent('click', { bubbles: true, composed: true, cancelable: true }),
+  );
+  await wait(0);
+}
+
+/** A finger held still until the gesture resolves. */
+async function hold(el: EventTarget) {
+  press(el, 'pointerdown');
+  await wait(HELD);
+  press(el, 'pointerup');
+  await wait(0);
+}
+
+async function mountList() {
+  const el = await fixture('track-list');
+
+  (el as unknown as { tracks: unknown[] }).tracks = TRACKS;
+  await flush();
+  await el.updateComplete;
+  await wait(60);
+  await el.updateComplete;
+
+  return el;
+}
+
+function rows(el: HTMLElement): HTMLElement[] {
+  return shadowAll<HTMLElement>(el, '.track-row');
+}
+
+describe('a finger on a track row', () => {
+  beforeEach(() => {
+    resetHarness();
+    stub('library.Library.GetTracks', TRACKS);
+    stub('library.Library.GetAllLibrariesWithTrackCounts', []);
+    stub('config.Config.GetShortcuts', {});
+    stub('queue.Queue.SetQueue', null);
+    stub('queue.Queue.AddTracksToQueue', null);
+    uninstall = installTouchGestures();
+  });
+
+  afterEach(() => {
+    uninstall?.();
+    uninstall = null;
+    vi.restoreAllMocks();
+  });
+
+  it('plays the row it taps, rather than selecting it', async () => {
+    const el = await mountList();
+    const row = rows(el)[1];
+
+    expect(row, 'the list rendered rows').toBeTruthy();
+
+    await tap(row!);
+    await flush();
+
+    const queued = calls('queue.Queue.SetQueue');
+
+    expect(queued.length, 'a tap plays').toBe(1);
+
+    // From that row, in the list as displayed -- not a queue of one
+    // that stops when the song ends.
+    expect(queued[0]?.args[1]).toBe(1);
+    expect((queued[0]?.args[0] as string[]).length).toBe(TRACKS.length);
+  });
+
+  it('leaves the same row to a mouse, which still selects', async () => {
+    // The inversion is per event, so one component answers both
+    // pointers at the same width. A viewport rule cannot say this.
+    const el = await mountList();
+    const row = rows(el)[1];
+
+    row!.dispatchEvent(
+      new MouseEvent('click', { bubbles: true, composed: true }),
+    );
+    await el.updateComplete;
+
+    expect(calls('queue.Queue.SetQueue').length, 'a click does not play').toBe(0);
+    expect(rows(el)[1]?.getAttribute('aria-selected')).toBe('true');
+  });
+
+  it('enters selection mode on a long press, with that row selected', async () => {
+    const el = await mountList();
+
+    await hold(rows(el)[2]!);
+    await el.updateComplete;
+
+    const bar = shadow(el, 'selection-bar');
+
+    expect(bar, 'the action bar appears').toBeTruthy();
+    expect((bar as unknown as { count: number }).count).toBe(1);
+    expect(rows(el)[2]?.getAttribute('aria-selected')).toBe('true');
+  });
+
+  it('does not open a context menu when it enters the mode', async () => {
+    // The gesture is claimed, so the layer must not fall through to
+    // the synthetic `contextmenu` that every other surface still gets.
+    const el = await mountList();
+
+    await hold(rows(el)[0]!);
+    await el.updateComplete;
+
+    const menu = shadow(el, 'menu-surface');
+
+    expect((menu as unknown as { active?: boolean } | null)?.active ?? false).toBe(
+      false,
+    );
+  });
+
+  it('toggles rows while the mode is on, instead of playing them', async () => {
+    const el = await mountList();
+
+    await hold(rows(el)[0]!);
+    await el.updateComplete;
+    await tap(rows(el)[2]!);
+    await el.updateComplete;
+
+    expect(calls('queue.Queue.SetQueue').length, 'no track was played').toBe(0);
+    expect(
+      (shadow(el, 'selection-bar') as unknown as { count: number }).count,
+    ).toBe(2);
+  });
+
+  it('leaves the mode when the last row is deselected', async () => {
+    // Android's own lists do this, and here it matters more than
+    // convention: the mode changes what a tap means, so a mode holding
+    // nothing is a list where tapping does nothing and the bar that
+    // would explain it is showing a count of zero.
+    const el = await mountList();
+
+    await hold(rows(el)[0]!);
+    await el.updateComplete;
+    await tap(rows(el)[0]!);
+    await el.updateComplete;
+
+    expect(shadow(el, 'selection-bar')).toBeFalsy();
+  });
+
+  it('keeps the favourite icon a favourite icon', async () => {
+    // It is inside a row whose tap now plays, and it has been a 44px
+    // target since #56 -- so without the "a control inside the row
+    // owns its own tap" rule, that target silently becomes a second
+    // play button.
+    const el = await mountList();
+    const fav = rows(el)[1]?.querySelector('.fav-icon');
+
+    expect(fav, 'a row renders a favourite control').toBeTruthy();
+
+    await tap(fav!);
+    await flush();
+
+    expect(calls('queue.Queue.SetQueue').length, 'tapping it does not play').toBe(
+      0,
+    );
+  });
+
+  it('does not play a row the finger scrolled from', async () => {
+    // The failure this exists for makes the list unusable rather than
+    // merely wrong: every flick to scroll would start a track.
+    const el = await mountList();
+    const row = rows(el)[1];
+
+    press(row!, 'pointerdown');
+    press(row!, 'pointermove', { clientX: 40, clientY: 200 });
+    press(row!, 'pointerup');
+    await flush();
+
+    expect(calls('queue.Queue.SetQueue').length).toBe(0);
+  });
+});
+
+describe('<selection-bar>', () => {
+  it('renders nothing with nothing selected', async () => {
+    const el = await fixture('selection-bar', { count: 0 });
+
+    expect(shadow(el, '.bar')).toBeFalsy();
+  });
+
+  it('announces the count, which changes under the finger', async () => {
+    const el = await fixture('selection-bar', { count: 3, actions: [] });
+    const live = shadow(el, '[aria-live="polite"]');
+
+    expect(live?.textContent?.trim()).toContain('3 tracks selected');
+  });
+
+  it('names one track in the singular', async () => {
+    const el = await fixture('selection-bar', { count: 1, actions: [] });
+
+    expect(shadow(el, '[aria-live="polite"]')?.textContent?.trim()).toContain(
+      '1 track selected',
+    );
+  });
+
+  it('keeps every control at the touch floor', async () => {
+    // #56 and #186. A bar a thumb uses, in the one mode that only a
+    // thumb can enter.
+    const el = await fixture('selection-bar', {
+      count: 2,
+      actions: [{ id: 'play', label: 'Play', icon: 'play' }],
+    });
+
+    const buttons = shadowAll<HTMLElement>(el, 'button');
+
+    expect(buttons.length).toBeGreaterThan(0);
+
+    for (const button of buttons) {
+      const box = button.getBoundingClientRect();
+
+      expect(
+        Math.min(Math.round(box.width), Math.round(box.height)),
+        button.getAttribute('aria-label') ?? '',
+      ).toBeGreaterThanOrEqual(44);
+    }
+  });
+});
+
+/**
+ * What the gestures leave behind (plan 019 phase 4, #63).
+ *
+ * Every track, album and artist name in a row is an `explore-link`,
+ * which navigates on a genuine single click — and a row's single
+ * *tap* now plays. That conflict is #67's to answer properly; what
+ * this plan committed to is the narrower half of it, that **tap-to-play
+ * wins on touch**, and it falls out of phase 1's design rather than
+ * needing a rule: a claimed tap has its click swallowed at document
+ * capture, so the link's own handler never runs.
+ *
+ * It falls out, which is exactly why it is asserted. Nothing else in
+ * the suite would fail if the swallow stopped covering the link, and
+ * the symptom — a tap on a track's title navigating to its album
+ * instead of playing it — is one a phone user meets constantly and a
+ * mouse user never does.
+ */
+describe('a tap on a name inside a row', () => {
+  beforeEach(() => {
+    resetHarness();
+    stub('library.Library.GetTracks', TRACKS);
+    stub('library.Library.GetAllLibrariesWithTrackCounts', []);
+    stub('config.Config.GetShortcuts', {});
+    stub('queue.Queue.SetQueue', null);
+    uninstall = installTouchGestures();
+  });
+
+  afterEach(() => {
+    uninstall?.();
+    uninstall = null;
+    vi.restoreAllMocks();
+  });
+
+  /** Where the row's title is rendered, which is a link. */
+  function titleLink(el: HTMLElement, row: number): HTMLElement {
+    const link = rows(el)[row]?.querySelector('.explore-link');
+
+    expect(link, 'the row renders its title as a link').toBeTruthy();
+
+    return link as HTMLElement;
+  }
+
+  it('plays the row rather than navigating', async () => {
+    const el = await mountList();
+    const navigations: Event[] = [];
+
+    document.addEventListener('navigate', (e) => navigations.push(e));
+
+    await tap(titleLink(el, 1));
+    await flush();
+    // `explore-link` holds a navigation for DOUBLE_CLICK_GRACE_MS, so
+    // asserting sooner passes on a build that is about to navigate.
+    await wait(EXPLORE_LINK_GRACE);
+
+    expect(calls('queue.Queue.SetQueue').length, 'the row played').toBe(1);
+    expect(navigations, 'and nothing navigated').toHaveLength(0);
+  });
+
+  it('toggles the row while selection mode is on', async () => {
+    const el = await mountList();
+    const navigations: Event[] = [];
+
+    document.addEventListener('navigate', (e) => navigations.push(e));
+
+    await hold(rows(el)[0]!);
+    await el.updateComplete;
+    await tap(titleLink(el, 2));
+    await el.updateComplete;
+    await wait(EXPLORE_LINK_GRACE);
+
+    expect(
+      (shadow(el, 'selection-bar') as unknown as { count: number }).count,
+    ).toBe(2);
+    expect(navigations).toHaveLength(0);
+  });
+
+  it('leaves the mode on Escape', async () => {
+    // A mode changes what a tap means, so it needs an exit that is not
+    // "find the x". It is a dismissal rather than a shortcut, which is
+    // why it is not a panel-scoped binding.
+    const el = await mountList();
+
+    await hold(rows(el)[0]!);
+    await el.updateComplete;
+
+    document.dispatchEvent(
+      new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }),
+    );
+    await el.updateComplete;
+
+    expect(shadow(el, 'selection-bar')).toBeFalsy();
+    expect(rows(el)[0]?.getAttribute('aria-selected')).toBe('false');
+  });
+});

frontend/test/components/touch-surfaces.test.ts

@@ -0,0 +1,333 @@
+/**
+ * The other three selecting surfaces (plan 019 phase 3, #63).
+ *
+ * `track-list` got the gestures in phases 1 and 2; the queue panel and
+ * both playlist detail views are the rest, and phase 3 was "mostly
+ * wiring" only in the sense that they already share
+ * `SelectionController`. Two of them are not symmetric with the track
+ * list at all, and those two asymmetries are what this file is for:
+ *
+ * **A tap on a queue row plays that position in the queue.** Copying
+ * `track-list`'s tap — which sets the queue to the list the row is in —
+ * would rebuild the queue from the queue, discarding its source, its
+ * shuffle order and everything inserted by hand along the way. It is
+ * not the no-op it reads as.
+ *
+ * **The queue panel has no swipe, deliberately.** A right swipe means
+ * *add to the queue* everywhere it exists, and a queue row is already
+ * in the queue; the only thing it could mean there is *remove*, which
+ * is the same gesture with the opposite effect one screen away. So the
+ * assertion is that the rows do not opt in — a swipe there must not
+ * silently become a second meaning for the app's one horizontal
+ * gesture.
+ *
+ * The playlist views are the symmetric half, and they are here because
+ * they bind their gestures **per template** rather than through the
+ * `firstUpdated` delegation the two virtualized lists use, so "the
+ * handler is attached at all" is a different question in each.
+ */
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+
+import '@components/queue-panel/queue-panel';
+import '@components/playlist-details/playlist-details';
+
+import { Events } from '../../src/events';
+import { calls, emit, flush, resetHarness, stub } from '@test/support/harness';
+import { fixture, shadow, shadowAll } from '@test/support/render';
+import { installTouchGestures, LONG_PRESS_MS } from '@utils/touch-gestures';
+import type { QueueTrack } from '@store/queue-store';
+
+const HELD = LONG_PRESS_MS + 120;
+const BRIEF = Math.round(LONG_PRESS_MS / 4);
+const wait = (ms: number) => new Promise((r) => setTimeout(r, ms));
+
+let uninstall: (() => void) | null = null;
+
+afterEach(() => {
+  // The layer is one document listener set, so a suite that leaves it
+  // installed makes the next file's gestures fire twice.
+  uninstall?.();
+  uninstall = null;
+});
+
+function queueTrack(n: number): QueueTrack {
+  return {
+    id: n,
+    audioFileId: n,
+    filePath: `/music/${n}.mp3`,
+    position: n,
+    title: `Track ${n}`,
+    artist: 'Artist',
+    album: 'Album',
+    coverArtPath: '',
+    artistMbid: '',
+    releaseGroupMbid: '',
+    recordingMbid: '',
+  };
+}
+
+const QUEUE = [1, 2, 3, 4].map(queueTrack);
+
+function playlistTrack(n: number) {
+  return {
+    ID: n,
+    FilePath: `/music/${n}.mp3`,
+    Title: `Track ${n}`,
+    Artist: 'Artist',
+    Album: 'Album',
+    Duration: 100 + n,
+    Position: n,
+    Phantom: false,
+  };
+}
+
+const PLAYLIST_TRACKS = [1, 2, 3, 4].map(playlistTrack);
+
+function press(el: EventTarget, type: string, init: PointerEventInit = {}) {
+  el.dispatchEvent(
+    new PointerEvent(type, {
+      bubbles: true,
+      composed: true,
+      cancelable: true,
+      pointerType: 'touch',
+      isPrimary: true,
+      clientX: 40,
+      clientY: 60,
+      ...init,
+    }),
+  );
+}
+
+async function tap(el: EventTarget) {
+  press(el, 'pointerdown');
+  await wait(BRIEF);
+  press(el, 'pointerup');
+  await wait(0);
+}
+
+async function hold(el: EventTarget) {
+  press(el, 'pointerdown');
+  await wait(HELD);
+  press(el, 'pointerup');
+  await wait(0);
+}
+
+/** Drag a row sideways by `dx` and lift, as one finger. */
+async function swipe(el: EventTarget, dx: number) {
+  const at = (x: number) =>
+    new Touch({
+      identifier: 1,
+      target: el as Element,
+      clientX: x,
+      clientY: 100,
+    });
+  const send = (type: string, points: Touch[]) =>
+    el.dispatchEvent(
+      new TouchEvent(type, {
+        bubbles: true,
+        composed: true,
+        cancelable: true,
+        touches: points,
+        changedTouches: points.length > 0 ? points : [at(0)],
+      }),
+    );
+
+  send('touchstart', [at(0)]);
+
+  for (const step of [0.25, 0.5, 0.75, 1]) {
+    send('touchmove', [at(dx * step)]);
+    await Promise.resolve();
+  }
+
+  send('touchend', []);
+  await wait(0);
+}
+
+/** Past any commit threshold the row could compute. */
+const FAR = 400;
+
+describe('a finger on a queue row', () => {
+  beforeEach(() => {
+    resetHarness();
+    stub('config.Config.GetShortcuts', {});
+    stub('queue.Queue.PlayIndex', null);
+    stub('queue.Queue.SetQueue', null);
+    stub('queue.Queue.AddTracks', null);
+    uninstall = installTouchGestures();
+  });
+
+  async function panel() {
+    const el = await fixture('queue-panel', { open: true });
+
+    emit(Events.QueueChanged, {
+      tracks: QUEUE,
+      currentIndex: 0,
+      shuffleMode: false,
+      repeatMode: 'off',
+      sourcePlaylistId: 0,
+    });
+    await flush();
+    await el.updateComplete;
+    await new Promise((r) => {
+      requestAnimationFrame(() => r(null));
+    });
+
+    return el;
+  }
+
+  const rows = (el: HTMLElement) => shadowAll<HTMLElement>(el, '.track-item');
+
+  it('plays that position rather than rebuilding the queue', async () => {
+    const el = await panel();
+
+    await tap(rows(el)[2]!);
+    await flush();
+
+    expect(calls('queue.Queue.PlayIndex')[0]?.args[0]).toBe(2);
+
+    // The asymmetry with `track-list`: setting the queue here would
+    // discard its source, its shuffle order and anything inserted by
+    // hand, which is not the no-op it reads as.
+    expect(calls('queue.Queue.SetQueue').length).toBe(0);
+  });
+
+  it('enters selection mode on a hold, with that row selected', async () => {
+    const el = await panel();
+
+    await hold(rows(el)[1]!);
+    await el.updateComplete;
+
+    const bar = shadow(el, 'selection-bar');
+
+    expect(bar, 'the action bar appears').toBeTruthy();
+    expect((bar as unknown as { count: number }).count).toBe(1);
+    expect(calls('queue.Queue.PlayIndex').length, 'and nothing played').toBe(0);
+  });
+
+  it('toggles rows while the mode is on, instead of playing them', async () => {
+    const el = await panel();
+
+    await hold(rows(el)[0]!);
+    await el.updateComplete;
+    await tap(rows(el)[2]!);
+    await el.updateComplete;
+
+    expect(calls('queue.Queue.PlayIndex').length).toBe(0);
+    expect(
+      (shadow(el, 'selection-bar') as unknown as { count: number }).count,
+    ).toBe(2);
+  });
+
+  it('has no swipe, which is a decision and not an omission', async () => {
+    const el = await panel();
+
+    expect(
+      rows(el)[1]?.hasAttribute('data-swipe'),
+      'the row does not opt into the shared rule',
+    ).toBe(false);
+
+    await swipe(rows(el)[1]!, FAR);
+    await flush();
+
+    // A right swipe means "add to the queue" everywhere it exists.
+    // The only thing it could mean on a queue row is "remove", which
+    // is the same gesture with the opposite effect one screen away.
+    expect(calls('queue.Queue.AddTracks').length).toBe(0);
+    expect(calls('queue.Queue.RemoveTracks').length).toBe(0);
+  });
+});
+
+describe('a finger on a playlist row', () => {
+  beforeEach(() => {
+    resetHarness();
+    stub('config.Config.GetShortcuts', {});
+    stub('playlist.Service.GetPlaylist', {
+      ID: 1,
+      Name: 'A Playlist',
+      TrackCount: PLAYLIST_TRACKS.length,
+    });
+    stub('playlist.Service.GetPlaylistTracks', PLAYLIST_TRACKS);
+    stub('queue.Queue.SetQueue', null);
+    stub('queue.Queue.AddTracks', null);
+    uninstall = installTouchGestures();
+  });
+
+  async function details() {
+    const el = await fixture('playlist-details', {
+      playlistId: 1,
+      playlistName: 'A Playlist',
+    });
+
+    await flush();
+    await el.updateComplete;
+    await wait(60);
+    await el.updateComplete;
+
+    return el;
+  }
+
+  const rows = (el: HTMLElement) => shadowAll<HTMLElement>(el, '.track-item');
+
+  it('plays the playlist from the row it taps', async () => {
+    const el = await details();
+
+    expect(rows(el).length, 'the list rendered rows').toBeGreaterThan(2);
+
+    await tap(rows(el)[2]!);
+    await flush();
+
+    const queued = calls('queue.Queue.SetQueue');
+
+    // The app's rule: activating one row plays the list that row is
+    // in, from that row -- not a queue of one that stops when the song
+    // ends.
+    expect(queued.length).toBe(1);
+    expect(queued[0]?.args[1]).toBe(2);
+    expect((queued[0]?.args[0] as string[]).length).toBe(
+      PLAYLIST_TRACKS.length,
+    );
+  });
+
+  it('enters selection mode on a hold', async () => {
+    const el = await details();
+
+    await hold(rows(el)[1]!);
+    await el.updateComplete;
+
+    expect(
+      (shadow(el, 'selection-bar') as unknown as { count: number } | null)
+        ?.count,
+    ).toBe(1);
+    expect(calls('queue.Queue.SetQueue').length, 'nothing played').toBe(0);
+  });
+
+  it('queues the row a swipe crosses', async () => {
+    const el = await details();
+
+    await swipe(rows(el)[1]!, FAR);
+    await flush();
+
+    expect(calls('queue.Queue.AddTracks')[0]?.args[0]).toEqual([
+      '/music/2.mp3',
+    ]);
+  });
+
+  it('opts its rows into the shared touch-action rule', async () => {
+    // Half of what makes the gesture reach us on the device, and
+    // invisible in this browser either way -- the other half is the
+    // non-passive preventDefault in `utils/touch-gestures.ts`.
+    const el = await details();
+
+    expect(rows(el)[0]?.hasAttribute('data-swipe')).toBe(true);
+
+    const css = (
+      customElements.get('playlist-details') as unknown as {
+        styles: { cssText: string }[];
+      }
+    ).styles
+      .map((s) => s.cssText)
+      .join('\n');
+
+    expect(css).toContain('touch-action: pan-y');
+  });
+});

frontend/test/components/touch-swipe.test.ts

@@ -0,0 +1,299 @@
+/**
+ * Swipe right on a track row to queue it (plan 019 phase 2, #63).
+ *
+ * `touch-gestures.test.ts` holds the recogniser — the axis rule, the
+ * claim, the guaranteed end. What is here is what the *list* does with
+ * it, and the two things that are only true of a list:
+ *
+ * **A swipe is not a selection.** It acts on the row it was made on,
+ * unless that row is one of several the user has explicitly chosen, in
+ * which case it acts on all of them — the same rule the context menu
+ * answers with, because a bar saying "40 selected" and a gesture that
+ * quietly queues one of them is two answers to the same question.
+ *
+ * **A short swipe is a no-op**, and that is the only thing standing
+ * between "add to queue" and a scroll that drifted sideways. The
+ * threshold is a fraction of the row, so it is measured from the row
+ * here rather than written down twice.
+ *
+ * What this tier cannot see is the device, and the reason is in the
+ * module's own header: Chrome 113's WebView cancels the pointer stream
+ * ~16px into any drag whatever `touch-action` says, so the gesture
+ * runs on touch events and needs `touch-action: pan-y` *and* a
+ * non-passive `preventDefault`. Both are correct in Chromium either
+ * way. The stylesheet half is asserted below for the same reason
+ * `hover-affordance.test.ts` reads a parsed stylesheet: the regression
+ * is someone tidying the declaration away, and nothing here renders
+ * differently when they do.
+ */
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+import '@components/track-list/track-list';
+
+import { calls, flush, resetHarness, stub } from '@test/support/harness';
+import { fixture, shadow, shadowAll } from '@test/support/render';
+import { installTouchGestures } from '@utils/touch-gestures';
+
+const wait = (ms: number) => new Promise((r) => setTimeout(r, ms));
+
+let uninstall: (() => void) | null = null;
+
+function track(n: number) {
+  return {
+    FilePath: `/music/track-${n}.mp3`,
+    TrackName: `Track ${n}`,
+    ArtistName: 'An Artist',
+    Album: 'An Album',
+    Duration: 100 + n,
+    ID: n,
+  };
+}
+
+const TRACKS = [track(1), track(2), track(3), track(4)];
+
+async function mountList() {
+  const el = await fixture('track-list');
+
+  // A definite width, because the commit threshold is a fraction of
+  // the row and a list that has not been given one is not a list.
+  el.style.display = 'block';
+  el.style.width = '400px';
+
+  (el as unknown as { tracks: unknown[] }).tracks = TRACKS;
+  await flush();
+  await el.updateComplete;
+  await wait(60);
+  await el.updateComplete;
+
+  return el;
+}
+
+function rows(el: HTMLElement): HTMLElement[] {
+  return shadowAll<HTMLElement>(el, '.track-row');
+}
+
+/**
+ * Drag a row sideways by `dx` and lift, as one finger.
+ *
+ * `onStep` runs after each move and is awaited, which is how the
+ * reveal is observed: the component writes the travel straight to the
+ * row's style but renders the pane through Lit, so it exists a frame
+ * after the move that asked for it, not during it.
+ */
+async function swipe(
+  el: EventTarget,
+  dx: number,
+  dy = 0,
+  onStep?: () => Promise<void> | void,
+): Promise<void> {
+  const at = (x: number, y: number) =>
+    new Touch({
+      identifier: 1,
+      target: el as Element,
+      clientX: x,
+      clientY: y,
+    });
+  const send = (type: string, points: Touch[]) =>
+    el.dispatchEvent(
+      new TouchEvent(type, {
+        bubbles: true,
+        composed: true,
+        cancelable: true,
+        touches: points,
+        changedTouches: points.length > 0 ? points : [at(0, 0)],
+      }),
+    );
+
+  send('touchstart', [at(0, 100)]);
+
+  // Several steps, because the recogniser claims the gesture on the
+  // move that crosses its threshold and the component reads every one
+  // after it.
+  for (const step of [0.25, 0.5, 0.75, 1]) {
+    send('touchmove', [at(dx * step, 100 + dy * step)]);
+    if (onStep) await onStep();
+  }
+
+  send('touchend', []);
+}
+
+/** Where the commit threshold falls for the row as rendered. */
+function threshold(row: HTMLElement): number {
+  return Math.max(72, row.getBoundingClientRect().width * 0.3);
+}
+
+describe('a finger swiped right across a track row', () => {
+  beforeEach(() => {
+    resetHarness();
+    stub('library.Library.GetTracks', TRACKS);
+    stub('library.Library.GetAllLibrariesWithTrackCounts', []);
+    stub('config.Config.GetShortcuts', {});
+    stub('queue.Queue.SetQueue', null);
+    stub('queue.Queue.AddTracks', null);
+    uninstall = installTouchGestures();
+  });
+
+  afterEach(() => {
+    uninstall?.();
+    uninstall = null;
+    vi.restoreAllMocks();
+  });
+
+  it('adds that row to the queue', async () => {
+    const el = await mountList();
+    const row = rows(el)[1];
+
+    expect(row, 'the list rendered rows').toBeTruthy();
+
+    await swipe(row!, threshold(row!) + 40);
+    await flush();
+
+    const queued = calls('queue.Queue.AddTracks');
+
+    expect(queued.length, 'one swipe, one call').toBe(1);
+    expect(queued[0]?.args[0]).toEqual(['/music/track-2.mp3']);
+
+    // It queues; it does not play. The row that was playing keeps
+    // playing, which is the difference from a tap.
+    expect(calls('queue.Queue.SetQueue').length).toBe(0);
+  });
+
+  it('does nothing when the finger did not get far enough', async () => {
+    const el = await mountList();
+    const row = rows(el)[1];
+
+    await swipe(row!, Math.round(threshold(row!)) - 10);
+    await flush();
+
+    expect(calls('queue.Queue.AddTracks').length).toBe(0);
+  });
+
+  it('leaves a scroll that began on a row to the list', async () => {
+    // The same shape as `touch-selection.test.ts`'s "does not play a
+    // row the finger scrolled from", one gesture over: the failure
+    // this guards against makes the list unusable rather than wrong.
+    const el = await mountList();
+    const row = rows(el)[1];
+
+    await swipe(row!, 30, 200);
+    await flush();
+
+    expect(calls('queue.Queue.AddTracks').length).toBe(0);
+  });
+
+  it('reveals what it will do, in words, while the finger is down', async () => {
+    const el = await mountList();
+    const row = rows(el)[1];
+    const reveals: (string | undefined)[] = [];
+
+    await swipe(row!, threshold(row!) + 40, 0, async () => {
+      await el.updateComplete;
+      reveals.push(
+        shadow(el, '[data-testid="swipe-reveal"]')?.textContent?.trim(),
+      );
+    });
+
+    // Not only a colour (WCAG 1.4.1): the pane says what it is for,
+    // and says something different once the gesture would commit.
+    expect(reveals.some((t) => t?.includes('Add to queue'))).toBe(true);
+    expect(reveals.some((t) => t?.includes('Release to add'))).toBe(true);
+  });
+
+  it('says what it did, for anyone not watching the row', async () => {
+    const el = await mountList();
+    const row = rows(el)[1];
+
+    await swipe(row!, threshold(row!) + 40);
+    await flush();
+    await el.updateComplete;
+
+    const said = shadowAll(el, '[role="status"]')
+      .map((r) => r.textContent?.trim())
+      .join(' ');
+
+    expect(said).toContain('Track 2');
+    expect(said).toContain('queue');
+  });
+
+  it('queues the whole selection when the row is part of one', async () => {
+    // One row is a position; several rows are an explicit choice. A
+    // gesture that quietly queued the one row touched would contradict
+    // the bar above it saying how many are selected.
+    const el = await mountList();
+
+    rows(el)[1]?.dispatchEvent(
+      new MouseEvent('click', { bubbles: true, composed: true }),
+    );
+    rows(el)[3]?.dispatchEvent(
+      new MouseEvent('click', {
+        bubbles: true,
+        composed: true,
+        ctrlKey: true,
+      }),
+    );
+    await el.updateComplete;
+
+    const row = rows(el)[1];
+
+    await swipe(row!, threshold(row!) + 40);
+    await flush();
+
+    expect(calls('queue.Queue.AddTracks')[0]?.args[0]).toEqual([
+      '/music/track-2.mp3',
+      '/music/track-4.mp3',
+    ]);
+  });
+
+  it('queues only the row it touched when that row is outside the selection', async () => {
+    const el = await mountList();
+
+    rows(el)[3]?.dispatchEvent(
+      new MouseEvent('click', { bubbles: true, composed: true }),
+    );
+    await el.updateComplete;
+
+    const row = rows(el)[0];
+
+    await swipe(row!, threshold(row!) + 40);
+    await flush();
+
+    expect(calls('queue.Queue.AddTracks')[0]?.args[0]).toEqual([
+      '/music/track-1.mp3',
+    ]);
+
+    // And it did not become a way of selecting anything.
+    expect(rows(el)[3]?.getAttribute('aria-selected')).toBe('true');
+    expect(rows(el)[0]?.getAttribute('aria-selected')).toBe('false');
+  });
+
+  it('declares pan-y on the row, which is half of what makes it work', async () => {
+    // The other half is the gesture module's non-passive
+    // `preventDefault`. Neither works alone on Chrome 113 and both are
+    // irrelevant here, so this reads the stylesheet and the attribute
+    // rather than the rendering — the regression is someone tidying
+    // one of them away, and nothing in this browser looks different
+    // when they do.
+    const el = await mountList();
+
+    expect(
+      rows(el)[0]?.hasAttribute('data-swipe'),
+      'the row opts into the shared rule',
+    ).toBe(true);
+
+    const sheets = (
+      customElements.get('track-list') as unknown as {
+        styles: { cssText: string }[];
+      }
+    ).styles;
+    const css = sheets.map((s) => s.cssText).join('\n');
+    const rule = css
+      .split('}')
+      .find((block) => /\[data-swipe\]\s*\{/.test(block));
+
+    expect(rule, 'the shared rule is in this component').toBeTruthy();
+    expect(rule).toContain('touch-action: pan-y');
+    expect(css, 'never none: it takes the scrolling too').not.toContain(
+      'touch-action: none',
+    );
+  });
+});

frontend/test/setup.ts

@@ -72,6 +72,23 @@ document.body.style.margin = '0';
 
 beforeEach(() => {
   resetHarness();
+
+  // A test file does not get its own origin. `@vitest/browser-playwright`
+  // opens one BrowserContext per session and runs several files in it,
+  // one after another, so everything a component persists — the track
+  // list's sort and column widths, the cover size, `now-playing`'s
+  // scroll mode — is still there when the next file mounts the same
+  // component. That is invisible until it is intermittent, because
+  // which files share a tab and in what order changes run to run: it
+  // cost #138 three scheduled runs, one of them a PR with no frontend
+  // code in it at all.
+  //
+  // Clearing here rather than in the specs that write is deliberate —
+  // the spec that *reads* is never the one that knows. It is safe for
+  // the same reason the leak exists: files in a session are
+  // sequential, so this cannot wipe storage a concurrent file is in
+  // the middle of using.
+  localStorage.clear();
 });
 
 afterEach(() => {

frontend/test/support/pixel.svg

@@ -0,0 +1,2 @@
+<!-- A real, servable image for the prefetch tests: one transparent pixel. -->
+<svg xmlns="http://www.w3.org/2000/svg" width="1" height="1"></svg>

frontend/test/utils/image-prefetch.test.ts

@@ -0,0 +1,113 @@
+/**
+ * What the grids ask for ahead of the scroll (#65).
+ *
+ * The virtualizer renders about 1000px past its viewport and nothing
+ * else can be asked for, because the `<img>` does not exist until the
+ * card does — two screens on the reference device, which is a fraction
+ * of a second at speed. `prefetchImageWindow` issues the request
+ * before the element, so the assertions here are about *which* rows
+ * are asked for, that none is asked for twice, and that a request is
+ * really made rather than merely recorded.
+ */
+import { describe, expect, it, beforeEach } from 'vitest';
+
+import {
+  PREFETCH_MEMORY,
+  imagePrefetched,
+  prefetchImage,
+  prefetchImageWindow,
+  resetImagePrefetch,
+} from '@utils/image-prefetch';
+
+/** A hundred cards, each with its own cover URL. */
+const CARDS = Array.from({ length: 100 }, (_, i) => ({ url: `/covers/${i}_sm.jpg` }));
+
+const urlOf = (card: { url: string }) => card.url;
+
+beforeEach(() => {
+  resetImagePrefetch();
+});
+
+describe('warming the images a scroll is about to reach', () => {
+  it('asks for the rows just past the rendered range, and no further', () => {
+    const issued = prefetchImageWindow(CARDS, 40, 50, urlOf, 3);
+
+    // Three past each edge: 51-53 and 37-39.
+    expect(issued).toBe(6);
+    expect(imagePrefetched('/covers/51_sm.jpg')).toBe(true);
+    expect(imagePrefetched('/covers/53_sm.jpg')).toBe(true);
+    expect(imagePrefetched('/covers/54_sm.jpg')).toBe(false);
+    expect(imagePrefetched('/covers/39_sm.jpg')).toBe(true);
+    expect(imagePrefetched('/covers/37_sm.jpg')).toBe(true);
+    expect(imagePrefetched('/covers/36_sm.jpg')).toBe(false);
+  });
+
+  it('leaves the rendered rows alone — they have their own <img>', () => {
+    prefetchImageWindow(CARDS, 40, 50, urlOf, 3);
+
+    expect(imagePrefetched('/covers/45_sm.jpg')).toBe(false);
+  });
+
+  it('asks for nothing twice, so a scroll back over the same rows is free', () => {
+    prefetchImageWindow(CARDS, 40, 50, urlOf, 3);
+
+    expect(prefetchImageWindow(CARDS, 40, 50, urlOf, 3)).toBe(0);
+  });
+
+  it('clamps at both ends of the list', () => {
+    // At the top of a five-item list nothing precedes the range, and
+    // the tail runs out after two.
+    expect(prefetchImageWindow(CARDS.slice(0, 5), 0, 2, urlOf, 10)).toBe(2);
+  });
+
+  it('asks for nothing when the virtualizer reports an empty range', () => {
+    // `visibilityChanged` reports -1/-1 before anything is laid out.
+    expect(prefetchImageWindow(CARDS, -1, -1, urlOf)).toBe(0);
+  });
+
+  it('skips a card that draws a placeholder rather than an image', () => {
+    expect(prefetchImageWindow(CARDS, 40, 50, () => '', 3)).toBe(0);
+  });
+
+  it('really issues the request, rather than only recording it', async () => {
+    // A served file, so the load succeeds and the resource timing entry
+    // is unambiguous; the query string keeps it distinct per run.
+    const url = `/test/support/pixel.svg?prefetch=${Date.now()}`;
+    const href = new URL(url, location.href).href;
+
+    expect(prefetchImage(url)).toBe(true);
+
+    for (let i = 0; i < 100; i++) {
+      if (performance.getEntriesByName(href).length > 0) break;
+
+      await new Promise((r) => setTimeout(r, 20));
+    }
+
+    expect(performance.getEntriesByName(href)).toHaveLength(1);
+    expect(prefetchImage(url)).toBe(false);
+    expect(performance.getEntriesByName(href)).toHaveLength(1);
+  });
+
+  it('reports what it is holding, with its cap, to the cache stats', () => {
+    prefetchImageWindow(CARDS, 40, 50, urlOf, 3);
+
+    const stat = window.__yjCacheStats?.()['imagePrefetch'];
+
+    expect(stat).toBeTruthy();
+    expect(stat!.entries).toBe(6);
+    expect(stat!.limit).toBe(PREFETCH_MEMORY);
+    // It holds URLs, not images — the bytes are the browser's cache.
+    expect(stat!.chars).toBe(6 * '/covers/51_sm.jpg'.length);
+  });
+
+  it('keeps its record bounded, so a 50 000-album scroll cannot grow it', () => {
+    const many = Array.from(
+      { length: PREFETCH_MEMORY * 2 },
+      (_, i) => ({ url: `/covers/bulk-${i}_sm.jpg` }),
+    );
+
+    prefetchImageWindow(many, 0, 0, urlOf, many.length);
+
+    expect(window.__yjCacheStats?.()['imagePrefetch']?.entries).toBe(PREFETCH_MEMORY);
+  });
+});

internal/testfixtures/fixtures_test.go

@@ -30,12 +30,6 @@ func TestFixturesMatchManifest(t *testing.T) {
 	m := testfixtures.Load(t)
 
 	for _, want := range m.Tracks {
-		// WAV tags are write-only today; see
-		// TestWAVTagsAreNotReadableYet.
-		if want.Format == "wav" {
-			continue
-		}
-
 		t.Run(want.Path, func(t *testing.T) {
 			t.Parallel()
 
@@ -161,39 +155,6 @@ func TestDuplicateFixturesAreIndistinguishable(t *testing.T) {
 	}
 }
 
-// TestWAVTagsAreNotReadableYet pins a known gap rather than hiding it.
-//
-// backend/tagwriter writes WAV tags into a RIFF "id3 " chunk, but
-// backend/metadata reads through dhowden/tag, which recognises MP3,
-// FLAC, OGG, MP4 and DSF and has no RIFF parser at all.  So every tag
-// the app writes to a WAV is invisible to the app that wrote it, and
-// WAV tracks always scan in as untitled.
-//
-// The fixtures are tagged correctly on disk, so when the reader learns
-// to unwrap the RIFF chunk this test starts failing — which is the
-// point.  Delete it then and drop the "wav" skip in
-// TestFixturesMatchManifest.
-func TestWAVTagsAreNotReadableYet(t *testing.T) {
-	t.Parallel()
-
-	m := testfixtures.Load(t)
-
-	for _, path := range m.Case(t, testfixtures.CaseWAVTracks) {
-		got, err := metadata.ExtractTags(path)
-		if err != nil {
-			t.Fatalf("extract tags from %s: %v", path, err)
-		}
-
-		if got.Title != "" {
-			t.Errorf(
-				"%s: WAV tags are now readable (%q) — good news; "+
-					"see this test's comment for what to update",
-				filepath.Base(path), got.Title,
-			)
-		}
-	}
-}
-
 func assertTag(t *testing.T, field string, want testfixtures.Track, got string) {
 	t.Helper()