feat(explore): let the album page be asked for the whole tracklist

An album the user holds part of showed only the tracks on disk, with
nothing to say the rest existed. The page could already draw the full
release with the missing rows dimmed -- it just could not be asked: the
automatic rule fires on `completeness.known`, which depends on the files
declaring a per-disc total, or failing that on the catalog's own
`total_tracks`.

Neither reaches most albums. #16 fixed the first input for anything
tagged from now on, and the second is worse than it looks: the published
artifact is from 2026-08-10 and the column landed on 08-16, so
`completenessAnswer()`'s catalog fallback answers 0 for every user until
the index job republishes. Measured, and noted on #88, which is the
publish that carries it.

So the control is explicit. A "Show the whole album" switch flips the
synthetic "Your Library" entry between the local files and the release,
which is the same rendering, reached deliberately rather than inferred.

Three things about it are load-bearing:

- `showFullTracklist` is a tri-state, `null` meaning "follow the
  automatic rule". The rule is right when it fires, and the switch has
  to agree with the page it is sitting on rather than starting out
  contradicting it -- a plain boolean would need its default recomputed
  every time the completeness answer moved underneath it. The user
  outranks the rule in both directions.
- `fullReleaseCluster()` falls back to the highest-scoring cluster.
  `findLibraryCluster` is a guess over the `inLibrary` flags and returns
  nothing at all when none are set, which is exactly the untagged
  library this exists for -- without the fallback the control would be
  absent precisely where it is needed. The sublabel names the release
  either way rather than leaving the user to wonder whose tracklist they
  are reading.
- It appears only where it can change what is on screen: against the
  library entry, with a release to switch to, and only when the two
  tracklists differ. A complete album's release has the same rows as its
  files, so the switch would redraw the same list and read as broken --
  the same test the version dropdown one section up already answers.

The accessible name is asserted rather than assumed, through the
browser's own computation. `wa-switch` happens to get it right, and for
a third reason again: its `<input role="switch">` sits inside a native
`<label>` that also holds the `<slot>`, so the name is computed across
the flattened tree from light-DOM text. This app has shipped the
opposite twice.

Closes #7

.gitea/workflows/unclaim.yml

@@ -58,8 +58,15 @@ jobs:
         run: |
           set -euo pipefail
 
+          # `ca-certificates` is named because `--no-install-recommends`
+          # skips it, and `ubuntu:24.04` ships no CA bundle of its own —
+          # so curl comes up unable to verify TLS against our own Gitea
+          # and fails with "error setting certificate file" (exit 77).
+          # Every other containerised workflow here spells it out for the
+          # same reason; this one did not, and cost a release cycle.
           apt-get update -qq
-          apt-get install -y -qq --no-install-recommends curl jq >/dev/null
+          apt-get install -y -qq --no-install-recommends \
+            ca-certificates curl jq >/dev/null
 
           label_id=$(
             curl -sSf -H "Authorization: token $TOKEN" "$API/labels?limit=100" |
@@ -78,8 +85,14 @@ jobs:
           # label answers the same as one that did, which is what makes
           # this safe to run on *every* close rather than only the ones
           # that were claimed.
+          # The body is captured, not discarded, so a refusal is
+          # diagnosable from this log alone.  Whether the automatic
+          # token carries issue-write scope is still unproven, and
+          # "DELETE returned 403" without Gitea's own sentence costs
+          # another merge to find out which of the two it is.
+          body=$(mktemp)
           code=$(
-            curl -sS -o /dev/null -w '%{http_code}' -X DELETE \
+            curl -sS -o "$body" -w '%{http_code}' -X DELETE \
               -H "Authorization: token $TOKEN" \
               "$API/issues/$ISSUE/labels/$label_id"
           )
@@ -88,6 +101,7 @@ jobs:
             204) echo "unclaim: #$ISSUE is closed and unclaimed" ;;
             *)
               echo "unclaim: DELETE returned $code for #$ISSUE" >&2
+              cat "$body" >&2
               exit 1
               ;;
           esac

.planning/NOTES.md

@@ -3483,3 +3483,54 @@ public tap.
 
 A guard added today does not protect a tag that points at yesterday. When
 re-pointing a tag, check what the workflows looked like *there*.
+
+## A tag reader looks at exactly one spelling of "total" (measured 2026-08-18)
+
+Writing #16's totals means matching the reader, which is
+`dhowden/tag`, and it is narrower than the specs are:
+
+- **Vorbis (FLAC, OGG): `TRACKTOTAL` and `DISCTOTAL` only.**
+  `vorbis.go`'s `Track()` reads `tracknumber` and `tracktotal` and
+  nothing else, so `TOTALTRACKS` — which several taggers write and
+  which xiph lists — and a `1/12` packed into `TRACKNUMBER` both read
+  back as *no total*. They write successfully. Nothing errors.
+- **ID3v2 (MP3): `TRCK`/`TPOS` as `n/N`**, via `parseXofN`. That is one
+  frame carrying two facts, which is why `applyPositionFrame` reads the
+  existing frame before writing either half.
+- **WAV: nothing at all.** There is no RIFF reader in the module, so a
+  WAV's `id3 ` chunk is invisible to `metadata.ExtractTags` — every
+  field, not just the totals. Filed as #104.
+
+The general shape, and the reason this is written down: a tag written
+under a name the reader does not look at is indistinguishable from one
+never written. So the tests assert the round trip through
+`metadata.ExtractTags` — the reader the *scan* uses — rather than
+through the bytes the writer produced.
+
+## The published catalog artifact predates `total_tracks` (measured 2026-08-18)
+
+```
+$ curl -sSI .../generic/yellowjacket-core-index/latest/core-index.db.zst
+last-modified: Mon, 10 Aug 2026 04:38:16 GMT
+content-length: 75417037
+
+$ sqlite3 core-index.db \
+    "SELECT COUNT(*) FROM pragma_table_info('explore_index') WHERE name='total_tracks';"
+0
+$ sqlite3 core-index.db "SELECT COUNT(*) FROM explore_index;"
+1079667
+```
+
+The column landed in the schema on 2026-08-16; the artifact is from
+08-10, and `index-artifact.yml` is a weekly cron, not a push trigger.
+So `completenessAnswer()`'s catalog fallback answers 0 for **every**
+user today — the machinery is correct and `artifactHasTotals()` is
+doing precisely its job, there is just no data behind it. Same position
+the credit tables are in; both ride on the next publish (#88).
+
+The general point, which is why this is written down rather than just
+fixed: **a probe that makes a column optional also makes its absence
+silent.** `artifactHasTotals` and `artifactHasCredits` are both correct
+and both mean a feature can ship, pass every test, and produce nothing
+for anybody without a single failure anywhere. Checking the *published
+file* is one query and is not implied by any tick in CI.

CLAUDE.md

@@ -1547,11 +1547,55 @@ shape as the encoding probe beside it.
 
 What neither side can give is *which* tracks are missing, only how many
 — so an incomplete album still browses, and that is now the exception
-rather than every album load. Two smaller consequences: existing databases
-read "unknown" until a rescan repopulates the column (which degrades to
-exactly the old behaviour, so nothing breaks), and our own `tagwriter`
-writes track and disc *numbers* but not totals, so autotagging a folder
-currently degrades the field this rests on.
+rather than every album load. One smaller consequence: existing databases
+read "unknown" until a rescan repopulates the column, which degrades to
+exactly the old behaviour, so nothing breaks.
+
+**And our own writers declare the total, because for a long time they
+did not.** `tagwriter` wrote track and disc *numbers* and dropped the
+totals, so autotagging an album actively **erased** the evidence this
+rests on: the release became MBID-matched — a green tick — while the
+field `GetAlbumCompleteness` reads stayed absent, which is exactly the
+"2 of 10 tracks, reported as in your library" the report described.
+`FieldTotalTracks` / `FieldTotalDiscs` are written by the autotag apply
+pass and by the download importer, and `dbsync` persists the track
+total to the row so the album page agrees with the file without waiting
+for a rescan.
+
+Five things about it are load-bearing, and four of them fail silently:
+
+- **The total is per *disc*, not per release**, because that is what
+  the tag form declares and what `GetAlbumCompleteness` **sums** per
+  disc — a release total written on every file multiplies a two-disc
+  album's expectation by two, and no library can then satisfy it.
+  `backend/tagtotals` is that derivation, once, because the two callers
+  must not import each other or the writer.
+- **The Vorbis names are `TRACKTOTAL` and `DISCTOTAL` and no other
+  spelling.** `dhowden/tag`'s Vorbis reader looks at exactly those two
+  keys, so a perfectly reasonable `TOTALTRACKS`, or a `1/12` inside
+  `TRACKNUMBER`, is written successfully and reads back as no total at
+  all. The tests assert the round trip through the reader the *scan*
+  uses rather than through the bytes, for that reason.
+- **ID3's number and total share one frame**, so writing either alone
+  has to read the other off the existing tag or it silently discards
+  it. A total with no number is not written: `/12` is what a reader
+  parses as track 0.
+- **The totals are written unconditionally, not on a diff.** The case
+  this exists for is a file that declares *no* total, which compares
+  equal to nothing and is exactly what a "only if it changed" guard
+  skips.
+- **A single-track download must not be totalled.** A `RecordingMBID`
+  anchor resolves `Expected` to that one track, so the same code would
+  tag a track off a twelve-track album "1 of 1" — and a declared total
+  outranks the catalog total that would otherwise have answered
+  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
+RIFF reader**, so nothing the tag writer puts in a WAV's `id3 ` chunk
+is visible to `metadata.ExtractTags` — not the totals and not the title
+either. `wav_test.go` reads that chunk itself, which is why no test
+ever noticed.
 
 **The absence is what gets marked, not the presence.** The tracklist
 put a green tick against every owned track and a legend underneath
@@ -1579,6 +1623,32 @@ side-effect worth knowing: this is what finally makes `ownership()`
 say something true here, since counting the displayed tracklist of a
 library-only entry could only ever produce "9 of 9".
 
+**And it can be asked, because the rule alone reaches too few albums.**
+That guard depends on two inputs the user does not control: the files
+declaring a per-disc total, and the catalog's own `total_tracks`. Where
+neither says — which is a great deal of any library, and *every* library
+until an artifact carrying the column is published — a partly-owned
+album showed only the tracks on disk with nothing to say the rest
+existed. `renderTracklistScope()` is the explicit route: a
+"Show the whole album" switch that flips the synthetic "Your Library"
+entry between the local files and the release, which is the rendering
+the page could already do and could only be *triggered* automatically.
+
+Three things about it are load-bearing. **`showFullTracklist` is a
+tri-state**, `null` meaning "follow the automatic rule": the rule is
+right when it fires and the switch has to be able to agree with the page
+it sits on rather than starting out contradicting it, which a plain
+boolean would need recomputed every time the completeness answer moved
+underneath it. **`fullReleaseCluster()` falls back to the
+highest-scoring cluster**, because `findLibraryCluster` is a guess over
+the `inLibrary` flags and returns *nothing* when none are set — which is
+exactly the untagged library the switch exists for, so without the
+fallback the control would be absent precisely where it is needed. And
+**it is shown only where it can change what is on screen**: against the
+library entry, with a release to switch to, and only when the two
+tracklists differ — the same test the version dropdown answers, one
+control over.
+
 **A dropdown is only a choice if the choices differ.** The version
 selector tested `versionEntries.length`, but a release group routinely
 has several releases — reissues, regional pressings, a remaster — whose

backend/autotag/apply.go

@@ -8,6 +8,7 @@ import (
 	"log/slog"
 
 	"yellowjacket/backend/database/sql/sqlcgen"
+	"yellowjacket/backend/tagtotals"
 )
 
 // TagChanges mirrors tagwriter.TagChanges — redefined here so the
@@ -28,6 +29,8 @@ const (
 	FieldYear        = "year"
 	FieldTrackNumber = "track_number"
 	FieldDiscNumber  = "disc_number"
+	FieldTotalTracks = "total_tracks"
+	FieldTotalDiscs  = "total_discs"
 	FieldCoverArt    = "cover_art"
 )
 
@@ -418,5 +421,32 @@ func buildChanges(
 		changes[FieldDiscNumber] = track.DiscNumber
 	}
 
+	// The totals are what says "2 of 10" rather than a bare tick, and
+	// dropping them here is what made autotagging an album *erase* the
+	// evidence: the release becomes MBID-matched while the field
+	// GetAlbumCompleteness reads stays absent.
+	//
+	// They are written unconditionally where the candidate has a
+	// tracklist, not only when they differ from the local value, because
+	// the common case is a file that declares no total at all -- which
+	// compares equal to nothing and would be skipped by a diff guard.
+	if tracks, discs := tagtotals.For(
+		candidatePositions(cand), track.DiscNumber,
+	); tracks > 0 {
+		changes[FieldTotalTracks] = tracks
+		changes[FieldTotalDiscs] = discs
+	}
+
 	return changes
 }
+
+// candidatePositions is the candidate's tracklist as bare positions.
+func candidatePositions(cand Candidate) []tagtotals.Position {
+	out := make([]tagtotals.Position, 0, len(cand.Tracks))
+
+	for _, t := range cand.Tracks {
+		out = append(out, tagtotals.Position{Disc: t.DiscNumber, Track: t.Position})
+	}
+
+	return out
+}

backend/autotag/buildchanges_test.go

@@ -0,0 +1,90 @@
+package autotag
+
+import "testing"
+
+// Autotagging an album used to *erase* the evidence that says "2 of 10":
+// the release became MBID-matched while the totals the files declared
+// went unwritten, so the album page showed a plain tick.  These pin the
+// two halves of the fix that are easy to get wrong silently.
+func TestBuildChanges_Totals(t *testing.T) {
+	t.Parallel()
+
+	twoDiscs := Candidate{
+		Tracks: []CandidateTrack{
+			{DiscNumber: 1, Position: 1},
+			{DiscNumber: 1, Position: 2},
+			{DiscNumber: 2, Position: 1},
+			{DiscNumber: 2, Position: 2},
+			{DiscNumber: 2, Position: 3},
+		},
+	}
+
+	tests := []struct {
+		name       string
+		cand       Candidate
+		local      LocalTrack
+		track      CandidateTrack
+		wantTracks any
+		wantDiscs  any
+	}{
+		{
+			// The common case, and the one a diff guard would skip: the
+			// file declares no total at all, so the total "has not
+			// changed" and would never be written.
+			name: "a file with no total gets one",
+			cand: Candidate{Tracks: []CandidateTrack{
+				{Position: 1}, {Position: 2}, {Position: 3},
+			}},
+			local:      LocalTrack{TrackNumber: 1},
+			track:      CandidateTrack{Position: 1},
+			wantTracks: 3,
+			wantDiscs:  1,
+		},
+		{
+			// 5 here would be the release's track count.  Summed once
+			// per disc by GetAlbumCompleteness that claims a ten-track
+			// expectation for a five-track album, which no library can
+			// ever satisfy.
+			name:       "a multi-disc release totals the track's own disc",
+			cand:       twoDiscs,
+			local:      LocalTrack{},
+			track:      CandidateTrack{DiscNumber: 2, Position: 1},
+			wantTracks: 3,
+			wantDiscs:  2,
+		},
+		{
+			name:       "the other disc gets its own total",
+			cand:       twoDiscs,
+			local:      LocalTrack{},
+			track:      CandidateTrack{DiscNumber: 1, Position: 1},
+			wantTracks: 2,
+			wantDiscs:  2,
+		},
+		{
+			// A candidate with no tracklist knows nothing, and writing
+			// a zero would claim it did.
+			name:       "a candidate with no tracklist writes no total",
+			cand:       Candidate{},
+			local:      LocalTrack{},
+			track:      CandidateTrack{Position: 1},
+			wantTracks: nil,
+			wantDiscs:  nil,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			changes := buildChanges(tc.local, tc.cand, tc.track)
+
+			if got := changes[FieldTotalTracks]; got != tc.wantTracks {
+				t.Errorf("%s: got %v, want %v", FieldTotalTracks, got, tc.wantTracks)
+			}
+
+			if got := changes[FieldTotalDiscs]; got != tc.wantDiscs {
+				t.Errorf("%s: got %v, want %v", FieldTotalDiscs, got, tc.wantDiscs)
+			}
+		})
+	}
+}

backend/autotagservice/fieldnames_test.go

@@ -0,0 +1,38 @@
+package autotagservice
+
+import (
+	"testing"
+
+	"yellowjacket/backend/autotag"
+	"yellowjacket/backend/tagwriter"
+)
+
+// twAdapter passes the diff map through unchanged, so autotag's field
+// constants and tagwriter's are the same keys written down twice --
+// deliberately, to keep autotag out of the write pipeline's import
+// graph.  A key that drifts does not fail to compile and does not fail
+// to write: the writer simply finds no entry under the name it looks
+// for, and the field is silently dropped.  That is what this pins, and
+// this package is the one place that imports both.
+func TestAutotagAndTagwriterAgreeOnFieldNames(t *testing.T) {
+	t.Parallel()
+
+	pairs := map[string][2]string{
+		"title":        {autotag.FieldTitle, tagwriter.FieldTitle},
+		"artist":       {autotag.FieldArtist, tagwriter.FieldArtist},
+		"album":        {autotag.FieldAlbum, tagwriter.FieldAlbum},
+		"album artist": {autotag.FieldAlbumArtist, tagwriter.FieldAlbumArtist},
+		"year":         {autotag.FieldYear, tagwriter.FieldYear},
+		"track number": {autotag.FieldTrackNumber, tagwriter.FieldTrackNumber},
+		"disc number":  {autotag.FieldDiscNumber, tagwriter.FieldDiscNumber},
+		"total tracks": {autotag.FieldTotalTracks, tagwriter.FieldTotalTracks},
+		"total discs":  {autotag.FieldTotalDiscs, tagwriter.FieldTotalDiscs},
+		"cover art":    {autotag.FieldCoverArt, tagwriter.FieldCoverArt},
+	}
+
+	for name, pair := range pairs {
+		if pair[0] != pair[1] {
+			t.Errorf("%s: autotag says %q, tagwriter says %q", name, pair[0], pair[1])
+		}
+	}
+}

backend/download/importer.go

@@ -12,6 +12,7 @@ import (
 	"strconv"
 	"strings"
 
+	"yellowjacket/backend/tagtotals"
 	"yellowjacket/backend/tagwriter"
 )
 
@@ -275,6 +276,25 @@ func (i *Importer) tagFile(p plannedFile, dl Download) error {
 		changes[tagwriter.FieldDiscNumber] = p.Track.DiscNumber
 	}
 
+	// An imported file should arrive knowing how much of the album it
+	// is one of, or the album reads as "in your library" from its first
+	// imported track onward.
+	//
+	// A *track* download is the case this must not touch: a
+	// RecordingMBID anchor resolves Expected to exactly that one track,
+	// so totalling it would write "1 of 1" onto a track off a
+	// twelve-track album -- a confident lie, and one that outranks the
+	// catalog's own total, which is the fallback that would otherwise
+	// have answered correctly.
+	if dl.RecordingMBID == "" {
+		if tracks, discs := tagtotals.For(
+			expectedPositions(dl.Expected), p.Track.DiscNumber,
+		); tracks > 0 {
+			changes[tagwriter.FieldTotalTracks] = tracks
+			changes[tagwriter.FieldTotalDiscs] = discs
+		}
+	}
+
 	if err := i.tags.WriteUntrackedFileTags(p.Source, changes); err != nil {
 		return fmt.Errorf("write tags: %w", err)
 	}
@@ -282,6 +302,18 @@ func (i *Importer) tagFile(p plannedFile, dl Download) error {
 	return nil
 }
 
+// expectedPositions is the download's resolved tracklist as bare
+// positions.
+func expectedPositions(expected []ExpectedTrack) []tagtotals.Position {
+	out := make([]tagtotals.Position, 0, len(expected))
+
+	for _, t := range expected {
+		out = append(out, tagtotals.Position{Disc: t.DiscNumber, Track: t.Position})
+	}
+
+	return out
+}
+
 // destinationFor computes a file's library path from the template.
 func (i *Importer) destinationFor(
 	p plannedFile,

backend/download/importer_test.go

@@ -446,3 +446,77 @@ func keysOf(m map[string]tagwriter.TagChanges) []string {
 
 	return out
 }
+
+// An imported album should arrive knowing its own size, or the album
+// page reads "in your library" from its first imported track onward --
+// which is the badge complaint this exists to answer.
+func TestImportWritesTheAlbumTotals(t *testing.T) {
+	t.Parallel()
+
+	f := newImportFixture(t,
+		"01 - Airbag.flac",
+		"02 - Paranoid Android.flac",
+		"03 - Subterranean Homesick Alien.flac",
+		"04 - Exit Music (For a Film).flac",
+	)
+
+	if _, err := f.importer.Import(
+		context.Background(),
+		fourTrackDownload(),
+		Result{Dir: f.dir, Files: f.files},
+		ImportOptions{LibraryRoot: f.root, WriteTags: true},
+	); err != nil {
+		t.Fatalf("Import: %v", err)
+	}
+
+	changes := f.tags.writes["01 - Airbag.flac"]
+	if changes == nil {
+		t.Fatal("no tag write recorded for the first track")
+	}
+
+	if got := changes[tagwriter.FieldTotalTracks]; got != 4 {
+		t.Errorf("%s: got %v, want 4", tagwriter.FieldTotalTracks, got)
+	}
+
+	if got := changes[tagwriter.FieldTotalDiscs]; got != 1 {
+		t.Errorf("%s: got %v, want 1", tagwriter.FieldTotalDiscs, got)
+	}
+}
+
+// A RecordingMBID anchor resolves Expected to exactly the one track it
+// asked for, so totalling it would tag a track off a twelve-track album
+// as "1 of 1" -- worse than saying nothing, because a declared total
+// outranks the catalog total that would have answered correctly.
+func TestImportWritesNoTotalsForATrackDownload(t *testing.T) {
+	t.Parallel()
+
+	f := newImportFixture(t, "01 - Airbag.flac")
+
+	dl := Download{
+		ID:            "dl-track",
+		LibraryID:     1,
+		RecordingMBID: "mbid-recording",
+		Artist:        "Radiohead",
+		Album:         "OK Computer",
+		Expected:      []ExpectedTrack{{Position: 1, Title: "Airbag"}},
+	}
+
+	if _, err := f.importer.Import(
+		context.Background(),
+		dl,
+		Result{Dir: f.dir, Files: f.files},
+		ImportOptions{LibraryRoot: f.root, WriteTags: true},
+	); err != nil {
+		t.Fatalf("Import: %v", err)
+	}
+
+	changes := f.tags.writes["01 - Airbag.flac"]
+	if changes == nil {
+		t.Fatal("no tag write recorded")
+	}
+
+	if _, ok := changes[tagwriter.FieldTotalTracks]; ok {
+		t.Errorf("%s written for a single-track download: %v",
+			tagwriter.FieldTotalTracks, changes[tagwriter.FieldTotalTracks])
+	}
+}

backend/tagtotals/tagtotals.go

@@ -0,0 +1,56 @@
+// Package tagtotals derives the totals a tag's "5/12" form declares.
+//
+// It exists because the two writers that know a release's full
+// tracklist -- the autotag apply pass and the download importer --
+// must not import each other or the tag writer, and because getting
+// the denominator wrong is invisible: a total that is too large marks
+// a complete album incomplete forever, and nothing fails.
+package tagtotals
+
+// Position is one track's place in a release.  A zero Disc means the
+// release did not say, which is disc 1.
+type Position struct {
+	Disc  int
+	Track int
+}
+
+// For returns the totals to write on a file sitting on disc `disc`:
+// how many tracks that disc has, and how many discs the release has.
+//
+// The track total is **per disc** and not the release's track count,
+// because that is what the tag form means and what
+// GetAlbumCompleteness sums -- summing a release total once per disc
+// would multiply a two-disc album's expectation by two.
+//
+// Tracks are counted by distinct position rather than by row: a
+// tracklist that lists a position twice is a defect in the source, and
+// counting it twice would put an album permanently out of reach of its
+// own total.
+func For(all []Position, disc int) (tracks, discs int) {
+	disc = normaliseDisc(disc)
+
+	seenTracks := make(map[int]struct{}, len(all))
+	seenDiscs := make(map[int]struct{}, 1)
+
+	for _, p := range all {
+		d := normaliseDisc(p.Disc)
+		seenDiscs[d] = struct{}{}
+
+		if d != disc || p.Track <= 0 {
+			continue
+		}
+
+		seenTracks[p.Track] = struct{}{}
+	}
+
+	return len(seenTracks), len(seenDiscs)
+}
+
+// normaliseDisc treats an undeclared disc as disc 1.
+func normaliseDisc(d int) int {
+	if d <= 0 {
+		return 1
+	}
+
+	return d
+}

backend/tagtotals/tagtotals_test.go

@@ -0,0 +1,92 @@
+package tagtotals_test
+
+import (
+	"testing"
+
+	"yellowjacket/backend/tagtotals"
+)
+
+func TestFor(t *testing.T) {
+	t.Parallel()
+
+	singleDisc := []tagtotals.Position{
+		{Disc: 0, Track: 1}, {Disc: 0, Track: 2}, {Disc: 0, Track: 3},
+	}
+
+	twoDiscs := []tagtotals.Position{
+		{Disc: 1, Track: 1},
+		{Disc: 1, Track: 2},
+		{Disc: 2, Track: 1},
+		{Disc: 2, Track: 2},
+		{Disc: 2, Track: 3},
+	}
+
+	tests := []struct {
+		name       string
+		all        []tagtotals.Position
+		disc       int
+		wantTracks int
+		wantDiscs  int
+	}{
+		{
+			name: "a single-disc release totals its own tracks",
+			all:  singleDisc, disc: 0, wantTracks: 3, wantDiscs: 1,
+		},
+		{
+			// An undeclared disc is disc 1, on both sides of the
+			// question -- a file tagged "disc 1" and a tracklist that
+			// declares no disc describe the same disc.
+			name: "an undeclared disc is disc 1",
+			all:  singleDisc, disc: 1, wantTracks: 3, wantDiscs: 1,
+		},
+		{
+			// The whole point: 5 here would be the release's track
+			// count, which summed once per disc claims a ten-track
+			// expectation for a five-track album.
+			name: "a multi-disc release totals the file's own disc",
+			all:  twoDiscs, disc: 2, wantTracks: 3, wantDiscs: 2,
+		},
+		{
+			name: "the other disc gets its own total",
+			all:  twoDiscs, disc: 1, wantTracks: 2, wantDiscs: 2,
+		},
+		{
+			// A disc the tracklist does not mention cannot be totalled,
+			// and 0 is how the caller is told to write nothing.
+			name: "a disc with no tracks totals nothing",
+			all:  twoDiscs, disc: 3, wantTracks: 0, wantDiscs: 2,
+		},
+		{
+			name: "an empty tracklist totals nothing",
+			all:  nil, disc: 1, wantTracks: 0, wantDiscs: 0,
+		},
+		{
+			// A source that lists a position twice would otherwise put
+			// the album permanently one track short of its own total.
+			name: "a repeated position counts once",
+			all: []tagtotals.Position{
+				{Disc: 1, Track: 1}, {Disc: 1, Track: 1}, {Disc: 1, Track: 2},
+			},
+			disc: 1, wantTracks: 2, wantDiscs: 1,
+		},
+		{
+			name: "a track with no position is not counted",
+			all: []tagtotals.Position{
+				{Disc: 1, Track: 0}, {Disc: 1, Track: 1},
+			},
+			disc: 1, wantTracks: 1, wantDiscs: 1,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			tracks, discs := tagtotals.For(tc.all, tc.disc)
+			if tracks != tc.wantTracks || discs != tc.wantDiscs {
+				t.Errorf("For(%v, %d) = (%d, %d), want (%d, %d)",
+					tc.all, tc.disc, tracks, discs, tc.wantTracks, tc.wantDiscs)
+			}
+		})
+	}
+}

backend/tagwriter/dbsync.go

@@ -183,6 +183,15 @@ func syncDatabase(
 		discNum = toNullInt64(v)
 	}
 
+	// The completeness evidence.  Without this the row keeps whatever
+	// the last scan read while the file on disk now declares a total,
+	// so the album stays "unknown" until a full rescan -- which is the
+	// state the report describes.
+	totalTracks := old.TotalTracks
+	if v, ok := asInt(params.changes[FieldTotalTracks]); ok {
+		totalTracks = toNullInt64(v)
+	}
+
 	composer := old.Composer
 	if v, ok := params.changes[FieldComposer].(string); ok {
 		composer = v
@@ -207,7 +216,7 @@ func syncDatabase(
 		AlbumID:            albumID,
 		TrackNumber:        trackNum,
 		DiscNumber:         discNum,
-		TotalTracks:        old.TotalTracks,
+		TotalTracks:        totalTracks,
 		Year:               year,
 		Composer:           composer,
 		Comment:            old.Comment,

backend/tagwriter/flac.go

@@ -101,6 +101,11 @@ func applyFlacTextChanges(cmt *flacvorbis.MetaDataBlockVorbisComment, changes Ta
 		{FieldYear, flacvorbis.FIELD_DATE, true},
 		{FieldTrackNumber, flacvorbis.FIELD_TRACKNUMBER, true},
 		{FieldDiscNumber, "DISCNUMBER", true},
+		// TRACKTOTAL/DISCTOTAL and no other spelling: dhowden/tag's
+		// Vorbis reader looks at exactly these two keys, so TOTALTRACKS
+		// or a "1/12" inside TRACKNUMBER reads back as no total at all.
+		{FieldTotalTracks, "TRACKTOTAL", true},
+		{FieldTotalDiscs, "DISCTOTAL", true},
 		{FieldComposer, "COMPOSER", false},
 	}
 

backend/tagwriter/mp3.go

@@ -6,6 +6,7 @@ import (
 	"log/slog"
 	"os"
 	"strconv"
+	"strings"
 
 	id3v2 "github.com/bogem/id3v2/v2"
 
@@ -66,17 +67,10 @@ func applyTextChanges(tag *id3v2.Tag, changes TagChanges) {
 		tag.SetYear(strconv.Itoa(v))
 	}
 
-	if v, ok := asInt(changes[FieldTrackNumber]); ok {
-		trckID := tag.CommonID("Track number/Position in set")
-		tag.DeleteFrames(trckID)
-		tag.AddTextFrame(trckID, id3v2.EncodingUTF8, strconv.Itoa(v))
-	}
-
-	if v, ok := asInt(changes[FieldDiscNumber]); ok {
-		tposID := tag.CommonID("Part of a set")
-		tag.DeleteFrames(tposID)
-		tag.AddTextFrame(tposID, id3v2.EncodingUTF8, strconv.Itoa(v))
-	}
+	applyPositionFrame(tag, "Track number/Position in set", changes,
+		FieldTrackNumber, FieldTotalTracks)
+	applyPositionFrame(tag, "Part of a set", changes,
+		FieldDiscNumber, FieldTotalDiscs)
 
 	if v, ok := changes[FieldComposer].(string); ok {
 		tag.DeleteFrames("TCOM")
@@ -90,6 +84,64 @@ func applyTextChanges(tag *id3v2.Tag, changes TagChanges) {
 	}
 }
 
+// applyPositionFrame writes an ID3v2 position frame (TRCK or TPOS) in
+// the "n/N" form the readers parse.
+//
+// The number and the total are separate diff entries and either may be
+// absent, so the frame's *existing* value is the base: writing a total
+// alone must not discard the number that is already there, and writing
+// a number alone must not discard a total the file already declared.
+// A total with no number at all is not written, since "/12" says
+// nothing a reader can use.
+func applyPositionFrame(
+	tag *id3v2.Tag, description string, changes TagChanges, numKey, totalKey string,
+) {
+	_, hasNum := changes[numKey]
+	_, hasTotal := changes[totalKey]
+
+	if !hasNum && !hasTotal {
+		return
+	}
+
+	frameID := tag.CommonID(description)
+
+	num, total := parseXofN(
+		strings.TrimRight(tag.GetTextFrame(frameID).Text, "\x00 \t\n\r"),
+	)
+
+	if v, ok := asInt(changes[numKey]); ok {
+		num = v
+	}
+
+	if v, ok := asInt(changes[totalKey]); ok {
+		total = v
+	}
+
+	if num <= 0 {
+		return
+	}
+
+	value := strconv.Itoa(num)
+	if total > 0 {
+		value += "/" + strconv.Itoa(total)
+	}
+
+	tag.DeleteFrames(frameID)
+	tag.AddTextFrame(frameID, id3v2.EncodingUTF8, value)
+}
+
+// parseXofN splits an ID3v2 "n/N" position value.  A bare "n" yields a
+// zero total, and anything unparseable yields zeros — the same reading
+// dhowden/tag gives the frame.
+func parseXofN(s string) (int, int) {
+	numText, totalText, _ := strings.Cut(s, "/")
+
+	num, _ := strconv.Atoi(strings.TrimSpace(numText))
+	total, _ := strconv.Atoi(strings.TrimSpace(totalText))
+
+	return num, total
+}
+
 // applyCoverArtChanges handles the FieldCoverArt entry in the diff map.
 //
 //   - []byte with len > 0: embed the given image as front cover.

backend/tagwriter/ogg_vorbis.go

@@ -166,6 +166,8 @@ var oggFieldMappings = []struct { //nolint:gochecknoglobals // field mapping tab
 	{FieldYear, "DATE", true},
 	{FieldTrackNumber, "TRACKNUMBER", true},
 	{FieldDiscNumber, "DISCNUMBER", true},
+	{FieldTotalTracks, "TRACKTOTAL", true},
+	{FieldTotalDiscs, "DISCTOTAL", true},
 	{FieldComposer, "COMPOSER", false},
 }
 

backend/tagwriter/pipeline_test.go

@@ -333,3 +333,31 @@ func TestWriteTrackTags_DBSync(t *testing.T) {
 		t.Error("expected FTS5 result for 'New Title'")
 	}
 }
+
+// The row is what the album page reads, and it is only refreshed by a
+// scan.  Leaving total_tracks at whatever the last scan saw means an
+// album autotagged just now stays "unknown" -- a plain tick on an album
+// the user holds two tracks of -- until a full rescan happens to run.
+func TestWriteTrackTags_PersistsTheTotal(t *testing.T) {
+	db := database.NewTestDB(t)
+	dir := t.TempDir()
+	trackID := seedTestTrack(t, db, createPipelineTestMP3(t, dir))
+
+	tw := NewTagWriter(testLogger(), db, &mockPlayer{}, &mockPipelineLocker{})
+
+	if err := tw.WriteTrackTags(trackID, TagChanges{
+		FieldTrackNumber: 2,
+		FieldTotalTracks: 10,
+	}); err != nil {
+		t.Fatalf("WriteTrackTags: %v", err)
+	}
+
+	af, err := db.Queries.GetAudioFile(context.Background(), trackID)
+	if err != nil {
+		t.Fatalf("get audio file: %v", err)
+	}
+
+	if !af.TotalTracks.Valid || af.TotalTracks.Int64 != 10 {
+		t.Errorf("total_tracks: got %v, want 10", af.TotalTracks)
+	}
+}

backend/tagwriter/tagwriter.go

@@ -26,6 +26,15 @@ const (
 	FieldDiscNumber  = "disc_number"
 	FieldComposer    = "composer"
 	FieldCoverArt    = "cover_art" // []byte for set, nil for clear
+
+	// FieldTotalTracks is how many tracks are on *this file's disc*, not
+	// in the whole release.  That is what the "5/12" form declares and
+	// what GetAlbumCompleteness sums per disc; a release total written
+	// here would multiply the expectation by the number of discs.
+	FieldTotalTracks = "total_tracks"
+
+	// FieldTotalDiscs is how many discs the release has.
+	FieldTotalDiscs = "total_discs"
 )
 
 // AudioFormat represents a supported audio file format.

backend/tagwriter/totals_test.go

@@ -0,0 +1,199 @@
+package tagwriter
+
+import (
+	"path/filepath"
+	"testing"
+
+	"yellowjacket/backend/metadata"
+)
+
+// The totals are the evidence GetAlbumCompleteness reads, and every way
+// of getting them wrong is silent: a tag written under a name the
+// reader does not look at reads back as no total at all, which is
+// 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
+// RIFF reader at all, so metadata.ExtractTags cannot see a WAV's ID3
+// chunk -- which is why every other test here reads that chunk itself.
+func TestWriteTotals_RoundTripsInEveryFormat(t *testing.T) {
+	t.Parallel()
+
+	changes := TagChanges{
+		FieldTitle:       "Some Song",
+		FieldTrackNumber: 2,
+		FieldTotalTracks: 10,
+		FieldDiscNumber:  1,
+		FieldTotalDiscs:  2,
+	}
+
+	viaScanner := func(t *testing.T, path string) *metadata.TrackMetadata {
+		t.Helper()
+
+		meta, err := metadata.ExtractTags(path)
+		if err != nil {
+			t.Fatalf("ExtractTags: %v", err)
+		}
+
+		return meta
+	}
+
+	tests := []struct {
+		name  string
+		write func(t *testing.T, dir string) string
+		read  func(t *testing.T, path string) *metadata.TrackMetadata
+	}{
+		{
+			name: "mp3",
+			read: viaScanner,
+			write: func(t *testing.T, dir string) string {
+				t.Helper()
+
+				path := createTestMP3(t, dir, "totals.mp3", nil)
+				if err := writeMp3Tags(testLogger(), path, changes); err != nil {
+					t.Fatalf("writeMp3Tags: %v", err)
+				}
+
+				return path
+			},
+		},
+		{
+			name: "flac",
+			read: viaScanner,
+			write: func(t *testing.T, dir string) string {
+				t.Helper()
+
+				path := filepath.Join(dir, "totals.flac")
+				makeMinimalFLAC(t, path)
+
+				if err := writeFlacTags(testLogger(), path, changes); err != nil {
+					t.Fatalf("writeFlacTags: %v", err)
+				}
+
+				return path
+			},
+		},
+		{
+			name: "ogg",
+			read: viaScanner,
+			write: func(t *testing.T, dir string) string {
+				t.Helper()
+
+				path := filepath.Join(dir, "totals.ogg")
+				createTestOGG(t, path)
+
+				if err := writeOggTags(testLogger(), path, changes); err != nil {
+					t.Fatalf("writeOggTags: %v", err)
+				}
+
+				return path
+			},
+		},
+		{
+			name: "wav",
+			read: readWavID3Tags,
+			write: func(t *testing.T, dir string) string {
+				t.Helper()
+
+				path := createTestWAV(t, dir, "totals.wav", nil)
+
+				if err := writeWavTags(testLogger(), path, changes); err != nil {
+					t.Fatalf("writeWavTags: %v", err)
+				}
+
+				return path
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			meta := tc.read(t, tc.write(t, t.TempDir()))
+
+			assertIntField(t, "TrackNumber", meta.TrackNumber, 2)
+			assertIntField(t, "TotalTracks", meta.TotalTracks, 10)
+			assertIntField(t, "DiscNumber", meta.DiscNumber, 1)
+			assertIntField(t, "TotalDiscs", meta.TotalDiscs, 2)
+		})
+	}
+}
+
+// A number and a total are separate diff entries, so writing one must
+// not discard the other.  For ID3v2 they share a single "n/N" frame,
+// which is the only place this can go wrong -- and it goes wrong by
+// silently zeroing a total the file already declared.
+func TestWriteMp3Totals_PartialUpdateKeepsTheOtherHalf(t *testing.T) {
+	t.Parallel()
+
+	t.Run("writing the number keeps the total", func(t *testing.T) {
+		t.Parallel()
+
+		dir := t.TempDir()
+		path := createTestMP3(t, dir, "seeded.mp3", TagChanges{
+			FieldTrackNumber: 2,
+			FieldTotalTracks: 10,
+		})
+
+		if err := writeMp3Tags(testLogger(), path, TagChanges{
+			FieldTrackNumber: 4,
+		}); err != nil {
+			t.Fatalf("writeMp3Tags: %v", err)
+		}
+
+		meta, err := metadata.ExtractTags(path)
+		if err != nil {
+			t.Fatalf("ExtractTags: %v", err)
+		}
+
+		assertIntField(t, "TrackNumber", meta.TrackNumber, 4)
+		assertIntField(t, "TotalTracks", meta.TotalTracks, 10)
+	})
+
+	t.Run("writing the total keeps the number", func(t *testing.T) {
+		t.Parallel()
+
+		dir := t.TempDir()
+		path := createTestMP3(t, dir, "seeded.mp3", TagChanges{
+			FieldTrackNumber: 7,
+		})
+
+		if err := writeMp3Tags(testLogger(), path, TagChanges{
+			FieldTotalTracks: 12,
+		}); err != nil {
+			t.Fatalf("writeMp3Tags: %v", err)
+		}
+
+		meta, err := metadata.ExtractTags(path)
+		if err != nil {
+			t.Fatalf("ExtractTags: %v", err)
+		}
+
+		assertIntField(t, "TrackNumber", meta.TrackNumber, 7)
+		assertIntField(t, "TotalTracks", meta.TotalTracks, 12)
+	})
+
+	// "/12" says nothing a reader can use, and dhowden/tag reads it as
+	// track 0 -- which the scan would store as a real track number.
+	t.Run("a total with no number writes nothing", func(t *testing.T) {
+		t.Parallel()
+
+		dir := t.TempDir()
+		path := createTestMP3(t, dir, "bare.mp3", nil)
+
+		if err := writeMp3Tags(testLogger(), path, TagChanges{
+			FieldTotalTracks: 12,
+		}); err != nil {
+			t.Fatalf("writeMp3Tags: %v", err)
+		}
+
+		meta, err := metadata.ExtractTags(path)
+		if err != nil {
+			t.Fatalf("ExtractTags: %v", err)
+		}
+
+		assertIntField(t, "TrackNumber", meta.TrackNumber, 0)
+		assertIntField(t, "TotalTracks", meta.TotalTracks, 0)
+	})
+}

backend/tagwriter/wav_test.go

@@ -522,19 +522,20 @@ func readWavID3Tags(
 		}
 	}
 
-	// Track number (TRCK).
+	// Track number and total (TRCK), disc number and total (TPOS).
+	// Both carry the "n/N" form, so they are read the way a reader
+	// reads them rather than with Atoi -- which sees "2/10" as 0.
 	trckID := parsed.CommonID("Track number/Position in set")
 	if frames := parsed.GetFrames(trckID); len(frames) > 0 {
 		if tf, ok := frames[0].(id3v2.TextFrame); ok {
-			meta.TrackNumber = atoiSafe(tf.Text)
+			meta.TrackNumber, meta.TotalTracks = parseXofN(tf.Text)
 		}
 	}
 
-	// Disc number (TPOS).
 	tposID := parsed.CommonID("Part of a set")
 	if frames := parsed.GetFrames(tposID); len(frames) > 0 {
 		if tf, ok := frames[0].(id3v2.TextFrame); ok {
-			meta.DiscNumber = atoiSafe(tf.Text)
+			meta.DiscNumber, meta.TotalDiscs = parseXofN(tf.Text)
 		}
 	}
 

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

@@ -193,6 +193,25 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
     @state() private selectedVersionKey: string = '';
     @state() private coverArtURL = '';
 
+    /**
+     * Whether to draw the whole release rather than only the files on
+     * disk — `null` while nobody has said, which is the automatic rule
+     * (`buildLibraryEntry`: show the release once the tags say the album
+     * is incomplete).
+     *
+     * It is a *tri-state* on purpose. The automatic rule is right when
+     * it fires and the switch has to be able to agree with it, or the
+     * control would start out contradicting the page it is sitting on;
+     * a plain boolean would need its default recomputed every time the
+     * completeness answer changed underneath it.
+     *
+     * The rule alone was not enough, which is the report: it depends on
+     * the files declaring a per-disc total, so a library whose tags
+     * never said sat permanently on "only my tracks" with no way to ask
+     * for the rest — and no way to tell that there was a rest.
+     */
+    @state() private showFullTracklist: boolean | null = null;
+
     /**
      * The local album's own tracks — the authoritative answer to "what
      * is actually on disk," independent of `this.releases`, which
@@ -559,6 +578,19 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
             }
 
             /* ── Tracklist ── */
+            .tracklist-scope {
+                display: flex;
+                align-items: center;
+                flex-wrap: wrap;
+                gap: 6px 12px;
+                margin-bottom: 8px;
+            }
+
+            .tracklist-scope-hint {
+                font-size: var(--yj-text-xs);
+                color: var(--yj-text-tertiary, #888);
+            }
+
             .tracklist {
                 display: flex;
                 flex-direction: column;
@@ -914,6 +946,7 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
         this.releases = [];
         this.versionEntries = [];
         this.selectedVersionKey = '';
+        this.showFullTracklist = null;
         this.localTracks = [];
         this.filePaths = new Map();
         this.askedFor = new Set();
@@ -1817,17 +1850,23 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
             // Guarded on `known` rather than on "fewer tracks than the
             // cluster", which would swap in a catalog tracklist for
             // every album whose tags simply never declared a total.
+            //
+            // And guarded on the *user's* answer first, because the
+            // automatic rule can only fire where the tags declared a
+            // total: an album that says nothing is not an album that is
+            // complete, and it used to be shown as one.
             const answer = this.completenessAnswer();
-            const incomplete = answer?.known && !answer.complete;
 
-            if (incomplete) {
-                const fullRelease = this.findLibraryCluster(clusters);
+            if (this.showFullTracklist ?? (answer?.known && !answer.complete)) {
+                const fullRelease = this.fullReleaseCluster(clusters);
 
                 if (fullRelease) {
                     return {
                         key: 'synthetic:library',
                         label: 'Your Library',
-                        sublabel: `${answer?.owned ?? 0} of ${answer?.expected ?? 0} tracks · ${this.clusterLabel(fullRelease)}`,
+                        sublabel: answer?.known
+                            ? `${answer.owned} of ${answer.expected} tracks · ${this.clusterLabel(fullRelease)}`
+                            : `${this.clusterLabel(fullRelease)} · full tracklist`,
                         group: 'aggregate',
                         syntheticKind: 'library',
                         tracks: fullRelease.representative.tracks ?? [],
@@ -1861,6 +1900,25 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
         };
     }
 
+    /**
+     * The release to draw when the whole album is wanted rather than
+     * the files on disk.
+     *
+     * `findLibraryCluster` is the right answer where it has one — the
+     * release the user's tracks overlap most — but it is a guess over
+     * the `inLibrary` flags and returns nothing at all when none of
+     * them are set, which is every untagged library. Falling back to
+     * the highest-scoring cluster is what makes the switch work there;
+     * that is the same release the page would call "Standard", and the
+     * sublabel names it either way rather than leaving the user to
+     * wonder whose tracklist they are reading.
+     */
+    private fullReleaseCluster(
+        clusters: ReleaseCluster[],
+    ): ReleaseCluster | undefined {
+        return this.findLibraryCluster(clusters) ?? clusters[0];
+    }
+
     /**
      * Fallback only: used when there's no local album to anchor on
      * (see `buildLibraryEntry`). Finds the cluster with the highest
@@ -2238,6 +2296,7 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
                     @catalog-retry=${this.retryCatalog}
                 ></catalog-scope-notice>
                 ${this.renderVersionSelector()}
+                ${this.renderTracklistScope()}
                 ${this.renderTracklist()}
             </div>
             <track-details></track-details>
@@ -3036,6 +3095,86 @@ export class ExploreAlbumDetails extends LitElement implements ContextMenuHost {
 
     /* ── Tracklist ── */
 
+    /**
+     * "Show the whole album" — the switch between the files on disk and
+     * the release they are part of.
+     *
+     * The page could already draw the full release with the missing
+     * rows dimmed, and did so automatically once the tags said the
+     * album was incomplete. What it could not do was be *asked*: where
+     * the files declare no per-disc total and the catalog has none
+     * either, the rule never fires, so a partly-owned album showed only
+     * the tracks the user had and nothing said the rest existed.
+     *
+     * Three things about when it appears, all of them the same rule —
+     * a control that cannot change what is on screen is worse than no
+     * control, which is what the version dropdown's own guard is for:
+     *
+     * - Only against the synthetic "Your Library" entry. Every other
+     *   entry *is* a catalog tracklist already.
+     * - Only when a catalog release exists to switch to.
+     * - Only when the two differ. A complete album's release has the
+     *   same rows as its files, so the switch would redraw the same
+     *   list and read as broken.
+     */
+    private renderTracklistScope() {
+        const current = this.currentVersion();
+
+        if (current?.syntheticKind !== 'library') return nothing;
+        if (this.localTracks.length === 0) return nothing;
+
+        const full = this.fullReleaseCluster(this.clustersOf(this.versionEntries));
+        const fullCount = full?.representative.tracks?.length ?? 0;
+
+        if (fullCount === 0 || fullCount <= this.localTracks.length) {
+            return nothing;
+        }
+
+        const showing = current.tracks.length > this.localTracks.length;
+
+        return html`
+            <div class="tracklist-scope">
+                <wa-switch
+                    size="small"
+                    ?checked=${showing}
+                    @change=${this.handleTracklistScopeChange}
+                >
+                    Show the whole album
+                </wa-switch>
+                <span class="tracklist-scope-hint">
+                    ${showing
+                        ? `${this.localTracks.length} of ${fullCount} tracks are in your library`
+                        : `${fullCount - this.localTracks.length} more tracks are on this release`}
+                </span>
+            </div>
+        `;
+    }
+
+    /**
+     * The clusters behind the current entries.
+     *
+     * `buildClusters` computes them and keeps only the entries, so this
+     * recovers them rather than storing the array twice — two copies of
+     * a list rebuilt on four different events is how they come to
+     * disagree.
+     */
+    private clustersOf(entries: VersionEntry[]): ReleaseCluster[] {
+        return entries
+            .filter((e) => e.group === 'cluster')
+            .map((e) => e.cluster)
+            .filter((c): c is ReleaseCluster => !!c);
+    }
+
+    private handleTracklistScopeChange = (e: Event) => {
+        this.showFullTracklist = (e.target as HTMLInputElement).checked;
+
+        // The entries are derived, so the switch rebuilds them rather
+        // than patching the one it changed. `buildClusters` re-defaults
+        // the selection, which lands back on "Your Library" — the only
+        // entry this control is ever shown against.
+        this.buildClusters();
+    };
+
     /**
      * The heading is there and is not drawn.
      *

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

@@ -0,0 +1,238 @@
+/**
+ * Asking to see the whole album.
+ *
+ * The page could already draw the full release with the missing rows
+ * dimmed, and did so automatically once the tags said the album was
+ * incomplete. What it could not do was be *asked*: the rule depends on
+ * the files declaring a per-disc total, so where they declare none —
+ * which is a great deal of any library — a partly-owned album showed
+ * only the tracks on disk and nothing said the rest existed.
+ *
+ * The switch is the explicit route. Its rules are all one rule: a
+ * control that cannot change what is on screen is worse than no
+ * control, which is the same test the version dropdown answers.
+ */
+import { describe, expect, it, beforeEach } from 'vitest';
+import { page } from 'vitest/browser';
+import type { LitElement } from 'lit';
+
+import '@components/explore-album-details/explore-album-details';
+import { stub, flush, resetHarness } from '@test/support/harness';
+import { fixture, shadow, shadowAll } from '@test/support/render';
+
+const MBID = 'rg-0001';
+
+function track(n: number, owned = false) {
+  return {
+    position: n,
+    discNumber: 1,
+    title: `Track ${n}`,
+    length: 200000,
+    mbid: `rec-${n}`,
+    inLibrary: owned,
+  };
+}
+
+function release(mbid: string, date: string, trackCount: number, owned = 0) {
+  return {
+    mbid,
+    title: 'Glass Harbour',
+    date,
+    status: 'Official',
+    tracks: Array.from({ length: trackCount }, (_, i) =>
+      track(i + 1, i < owned),
+    ),
+  };
+}
+
+/** Local files with no recording MBIDs — an untagged rip, which is the
+ * case the automatic rule cannot see. */
+function localTracks(count: number) {
+  return Array.from({ length: count }, (_, i) => ({
+    TrackName: `Track ${i + 1}`,
+    TrackNumber: i + 1,
+    DiscNumber: 1,
+    TrackLength: '210000',
+    RecordingMBID: '',
+  }));
+}
+
+const UNKNOWN = { owned: 0, expected: 0, known: false, complete: false };
+
+async function albumWith(
+  releases: unknown[],
+  completeness: Record<string, unknown>,
+  local: unknown[] = [],
+): Promise<LitElement> {
+  stub('explore.Service.BrowseReleases', releases);
+  stub('library.Library.GetAlbumCompleteness', completeness);
+  stub('library.Library.GetAlbumTracks', local);
+
+  const el = await fixture<LitElement>('explore-album-details', {
+    releaseGroupMBID: MBID,
+    localAlbumId: 7,
+    albumName: 'Glass Harbour',
+  });
+
+  await flush();
+  await el.updateComplete;
+
+  return el;
+}
+
+const scopeSwitch = (el: LitElement) => shadow(el, '.tracklist-scope wa-switch');
+
+async function toggle(el: LitElement) {
+  const sw = scopeSwitch(el) as HTMLInputElement | null;
+  if (!sw) throw new Error('no tracklist scope switch on the page');
+
+  sw.checked = !sw.checked;
+  sw.dispatchEvent(new Event('change'));
+
+  await flush();
+  await el.updateComplete;
+}
+
+describe('the "show the whole album" switch', () => {
+  beforeEach(() => {
+    resetHarness();
+    stub('explore.Service.LookupReleaseGroup', {
+      mbid: MBID,
+      title: 'Glass Harbour',
+      artistCredit: 'Tideline',
+    });
+    stub('explore.Service.GetThumbnail', '');
+    stub('library.Library.GetAllLibrariesWithTrackCounts', []);
+    stub('library.Library.GetFilePathsByRecordingMBIDs', {});
+  });
+
+  /**
+   * The report, exactly: two tracks on disk, twelve on the release,
+   * and nothing to say so because the tags declared no total.
+   */
+  it('reveals the rest of the release when the total is unknown', async () => {
+    const el = await albumWith(
+      [release('rel-1', '2019-04-01', 12, 2)],
+      UNKNOWN,
+      localTracks(2),
+    );
+
+    expect(shadowAll(el, '.track-row')).toHaveLength(2);
+
+    await toggle(el);
+
+    const rows = shadowAll(el, '.track-row');
+    expect(rows).toHaveLength(12);
+    // Nothing resolves to a file, so every row is marked unowned —
+    // the dimming is the signal, and it is not this switch's job to
+    // invent ownership it cannot prove.
+    expect(rows.filter((r) => r.classList.contains('unowned'))).toHaveLength(12);
+  });
+
+  /** And back again — a switch that only goes one way is a button. */
+  it('goes back to the files on disk', async () => {
+    const el = await albumWith(
+      [release('rel-1', '2019-04-01', 12, 2)],
+      UNKNOWN,
+      localTracks(2),
+    );
+
+    await toggle(el);
+    expect(shadowAll(el, '.track-row')).toHaveLength(12);
+
+    await toggle(el);
+    expect(shadowAll(el, '.track-row')).toHaveLength(2);
+  });
+
+  /**
+   * The automatic rule still fires, and the control has to agree with
+   * the page it is sitting on rather than starting out contradicting
+   * it. This is what the tri-state is for.
+   */
+  it('starts checked when the tags already said the album is short', async () => {
+    stub(
+      'library.Library.GetFilePathsByRecordingMBIDs',
+      Object.fromEntries(
+        Array.from({ length: 9 }, (_, i) => [
+          `rec-${i + 1}`,
+          [`/music/0${i + 1}.mp3`],
+        ]),
+      ),
+    );
+
+    const el = await albumWith(
+      [release('rel-1', '2019-04-01', 12, 9)],
+      { owned: 9, expected: 12, known: true, complete: false },
+      localTracks(9),
+    );
+
+    expect(shadowAll(el, '.track-row')).toHaveLength(12);
+    expect((scopeSwitch(el) as HTMLInputElement).checked).toBe(true);
+  });
+
+  /** And the user outranks it: turning it off asks for the files. */
+  it('lets the automatic answer be overridden', async () => {
+    const el = await albumWith(
+      [release('rel-1', '2019-04-01', 12, 9)],
+      { owned: 9, expected: 12, known: true, complete: false },
+      localTracks(9),
+    );
+
+    await toggle(el);
+
+    expect(shadowAll(el, '.track-row')).toHaveLength(9);
+  });
+
+  /**
+   * A control the accessibility tree cannot name is not a control, and
+   * this app has shipped that fault twice — `wa-slider` pointed
+   * `aria-labelledby` at an empty internal label, and `config-field`
+   * rendered a `<label>` as a sibling with no `for`.
+   *
+   * `wa-switch` gets it right for a *different* reason than either:
+   * its `<input role="switch">` sits inside a native `<label>` that also
+   * holds the `<slot>`, so the name is computed across the flattened
+   * tree from light-DOM text. That is worth an assertion rather than an
+   * assumption — and it has to be the browser's own answer, since
+   * querying shadow roots cannot compute a name.
+   */
+  it('is named for anyone not looking at it', async () => {
+    await albumWith(
+      [release('rel-1', '2019-04-01', 12, 2)],
+      UNKNOWN,
+      localTracks(2),
+    );
+
+    await expect
+      .element(page.getByRole('switch', { name: 'Show the whole album' }))
+      .toBeInTheDocument();
+  });
+
+  describe('is absent where it could not change anything', () => {
+    it('when the album is entirely owned', async () => {
+      // Ten files, a ten-track release: the switch would redraw the
+      // same list, which reads as broken.
+      const el = await albumWith(
+        [release('rel-1', '2019-04-01', 10, 10)],
+        { owned: 10, expected: 10, known: true, complete: true },
+        localTracks(10),
+      );
+
+      expect(scopeSwitch(el)).toBeNull();
+    });
+
+    it('when there is no catalog release to switch to', async () => {
+      const el = await albumWith([], UNKNOWN, localTracks(4));
+
+      expect(scopeSwitch(el)).toBeNull();
+    });
+
+    it('when the album is not in the library at all', async () => {
+      // Every entry here is already a catalog tracklist; there is no
+      // "only my tracks" to go back to.
+      const el = await albumWith([release('rel-1', '2019-04-01', 12)], UNKNOWN);
+
+      expect(scopeSwitch(el)).toBeNull();
+    });
+  });
+});