fix(explore): clear in_library on a row that has no local id

`in_library = 1 AND local_*_id IS NULL` was a fixed point.
upsertBatch's conflict clause is `MAX(in_library, excluded.in_library)`,
so it can only ever raise the flag, and pruneStaleLocalCrossReferences —
which its own comment calls the only place a removal from the library is
reflected back into the index — was gated on the id being present. So
nothing in the app could clear such a row, ever: a permanent claim of
ownership with no local row to check it against.

The gate is now the flag *or* the id, for all three entity types. A NULL
id fails the existence test on its own, so this needs no second clause to
say what "not owned" means.

Nothing in the tree writes that shape today — collectLibraryEntities sets
both together — which is why this is worth closing rather than leaving:
the exposure is a database written by a version whose local-id columns
were populated differently, and the next writer that sets the flag
without an id, which nothing structurally prevents and which this shape
made permanent rather than merely wrong until the next scan.

The test seeds the row with raw SQL on purpose. upsertBatch writes a zero
LocalArtistID as literal 0, and 0 satisfies `IS NOT NULL`, so the old
gate already caught that shape — a fixture built through the upsert
cannot reproduce this at all. NULL is what the artifact importer and any
older writer leave behind, the columns being nullable with no default.
Reverted against the old gate, it fails on all three types.

Closes #118

backend/explore/prune_test.go

@@ -82,6 +82,100 @@ func TestPruneStaleLocalCrossReferences(t *testing.T) {
 	}
 }
 
+// TestPruneClearsInLibraryWithNoLocalID covers the fixed point: a row
+// carrying in_library with a NULL local_*_id.  The upsert's conflict
+// clause is `in_library = MAX(in_library, excluded.in_library)`, so it
+// can only ever raise the flag, and this pass used to be gated on the id
+// being present — which meant nothing in the app could clear such a row,
+// ever.  It is asserted for all three entity types because the gate was
+// written once and used three times, so a fix applied to one is a fix
+// that looks complete.
+//
+// The rows are seeded with raw SQL rather than through seedIndexResult
+// deliberately: upsertBatch writes a zero LocalArtistID as literal 0,
+// not NULL, and 0 satisfies `IS NOT NULL` — so the old gate already
+// caught that shape and a fixture built through the upsert cannot
+// reproduce this at all.  NULL is what the artifact importer and any
+// older writer leave behind, the column being nullable with no default.
+func TestPruneClearsInLibraryWithNoLocalID(t *testing.T) {
+	t.Parallel()
+
+	db := database.NewTestDB(t)
+	si := NewSearchIndex(db, nil, nil, slog.Default())
+
+	// A genuinely owned artist, to prove the wider gate does not simply
+	// clear everything it now looks at.
+	database.InsertTestTrack(t, db, database.TestTrack{
+		FilePath: "/music/owned.mp3",
+		Artist:   "Owned",
+	})
+
+	artist, err := db.Queries.GetArtistByName(t.Context(), "Owned")
+	if err != nil {
+		t.Fatalf("read seeded artist: %v", err)
+	}
+
+	seedIndexResult(t, db, SearchIndexResult{
+		EntityType:    EntityArtist,
+		MBID:          testMBID("owned"),
+		Title:         "Owned",
+		ArtistName:    "Owned",
+		ArtistMBID:    testMBID("owned"),
+		InLibrary:     true,
+		LocalArtistID: artist.ID,
+	})
+
+	orphans := []struct {
+		name       string
+		entityType string
+		mbid       string
+	}{
+		{"artist", EntityArtist, "orphan-artist"},
+		{"release group", EntityReleaseGroup, "orphan-release-group"},
+		{"recording", EntityRecording, "orphan-recording"},
+	}
+
+	for _, o := range orphans {
+		if _, err := db.ExecContext(
+			`INSERT INTO explore_index
+			     (entity_type, mbid, title, artist_name, artist_mbid,
+			      in_library,
+			      local_artist_id, local_release_group_id, local_recording_id)
+			 VALUES (?, ?, ?, ?, ?, 1, ?, ?, ?)`,
+			dbEntityType(o.entityType), dbMBID(testMBID(o.mbid)), o.name, o.name,
+			dbMBID(testMBID(o.mbid)),
+			nil, nil, nil,
+		); err != nil {
+			t.Fatalf("seed %s orphan: %v", o.name, err)
+		}
+	}
+
+	si.pruneStaleLocalCrossReferences()
+
+	inLibrary := func(t *testing.T, mbid string) int {
+		t.Helper()
+
+		var flag int
+		if err := db.QueryRowWriter(
+			"SELECT in_library FROM explore_index WHERE mbid = ?", dbMBID(mbid),
+		).Scan(&flag); err != nil {
+			t.Fatalf("read in_library for %q: %v", mbid, err)
+		}
+
+		return flag
+	}
+
+	for _, o := range orphans {
+		if got := inLibrary(t, testMBID(o.mbid)); got != 0 {
+			t.Errorf("%s with a NULL local id: in_library = %d, want 0", o.name, got)
+		}
+	}
+
+	if got := inLibrary(t, testMBID("owned")); got != 1 {
+		t.Errorf("owned artist: in_library = %d, want 1 (it still has a file)", got)
+	}
+}
+
 // TestUnenrichedLibraryArtistMBIDs_OrdersByOwnedTrackCount verifies the
 // backfill queue prioritizes artists by how many tracks the user actually
 // owns, not by how many duplicate-mbid artist rows happen to exist (the

backend/explore/searchindex.go

@@ -2562,6 +2562,19 @@ func (si *SearchIndex) PopulateLocalCrossReferences() {
 // The row itself is left in place (it may still be part of the shipped
 // catalog, just no longer owned) — only the "this is mine" bookkeeping
 // is cleared.
+//
+// It is gated on the flag *or* the id, not on the id alone.  Gated on
+// the id, `in_library = 1 AND local_*_id IS NULL` is a fixed point: the
+// upsert can only ever raise the flag and this pass skipped such a row
+// by construction, so nothing in the app could clear it — a row claiming
+// to be owned, permanently, with no local row to check the claim
+// against.  Nothing in the tree writes that shape today
+// (collectLibraryEntities sets both together), which is exactly why it
+// is worth closing now: the exposure is a database written by an older
+// version, and the next writer that sets the flag without an id, which
+// nothing structurally prevents.  A NULL id fails the existence test on
+// its own, so the wider gate needs no second clause to say what "not
+// owned" means.
 func (si *SearchIndex) pruneStaleLocalCrossReferences() {
 	type prune struct {
 		entityType string
@@ -2594,7 +2607,8 @@ func (si *SearchIndex) pruneStaleLocalCrossReferences() {
 		result, err := si.db.ExecContext(
 			`UPDATE explore_index
 			 SET in_library = 0, `+p.column+` = NULL
-			 WHERE entity_type = ? AND `+p.column+` IS NOT NULL
+			 WHERE entity_type = ?
+			   AND (`+p.column+` IS NOT NULL OR in_library = 1)
 			   AND NOT EXISTS (`+p.exists+`)`,
 			dbEntityType(p.entityType),
 		)

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

@@ -160,52 +160,29 @@ export class HomeView extends ViewLifecycleMixin(LitElement) {
                 user-select: none;
             }
 
-            /*
-             * The hover play button is a *hover* affordance, so it is
-             * 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 —
-             * 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.
-             *
-             * display:none outside the query rather than opacity:0 on
-             * its own: an opacity-0 button still takes taps and is
-             * still in the accessibility tree, so the invisible control
-             * would keep the hit area it was never meant to have on
-             * touch. Everything else stays inside, so the desktop
-             * animation is unchanged.
-             */
             .play {
-                display: none;
+                position: absolute;
+                right: 8px;
+                bottom: 8px;
+                width: 38px;
+                height: 38px;
+                border: none;
+                border-radius: 50%;
+                background: var(--yj-accent, #ffd43b);
+                color: var(--yj-accent-fg, #000);
+                display: flex;
+                align-items: center;
+                justify-content: center;
+                cursor: pointer;
+                opacity: 0;
+                transform: translateY(6px);
+                transition: opacity 0.12s ease, transform 0.12s ease;
             }
 
-            @media (hover: hover) and (pointer: fine) {
-                .play {
-                    position: absolute;
-                    right: 8px;
-                    bottom: 8px;
-                    width: 38px;
-                    height: 38px;
-                    border: none;
-                    border-radius: 50%;
-                    background: var(--yj-accent, #ffd43b);
-                    color: var(--yj-accent-fg, #000);
-                    display: flex;
-                    align-items: center;
-                    justify-content: center;
-                    cursor: pointer;
-                    opacity: 0;
-                    transform: translateY(6px);
-                    transition: opacity 0.12s ease, transform 0.12s ease;
-                }
-
-                .card:hover .play,
-                .card:focus-within .play {
-                    opacity: 1;
-                    transform: translateY(0);
-                }
+            .card:hover .play,
+            .card:focus-within .play {
+                opacity: 1;
+                transform: translateY(0);
             }
 
             .name {

frontend/test/components/hover-affordance.test.ts

@@ -1,85 +0,0 @@
-/**
- * A hover affordance is gated on the device having hover.
- *
- * The home page's cover cards reveal a play button on :hover. A touch
- * long-press synthesises a hover state in the WebView, so on a phone
- * that button flashed into view during the 500ms hold that
- * utils/long-press.ts is measuring for a context menu — a control
- * appearing because the user was reaching for a different one.
- *
- * This is asserted against the *parsed stylesheet* rather than by
- * emulating a touch device, and that is a limitation worth stating
- * rather than hiding. CDP's Emulation.setEmulatedMedia does not reach
- * this tier's iframe — matchMedia still answers `hover: hover` after it
- * is set — so there is no way here to render the component as a phone
- * would and read the computed style. What can be checked is the shape
- * the browser actually built from the css`` literal: that the reveal
- * lives inside a hover media query and that the default is display:none.
- *
- * Which is the regression worth catching anyway. The failure mode is
- * someone hoisting the rule back out of the query for a one-line tidy —
- * a change nothing renders differently on a desktop, so every other
- * assertion in this repo passes and the phone silently regresses.
- */
-import { describe, expect, it } from 'vitest';
-
-import '@components/home-view/home-view';
-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;
-}
-
-describe('the home card play button', () => {
-  it('reveals itself only where the device has hover', async () => {
-    const el = await fixture('home-view', {});
-    const rules = rulesOf(el);
-
-    // The sweep is worth nothing if it read no rules at all — the same
-    // first assertion icon-language.test.ts makes for the same reason.
-    expect(rules.length).toBeGreaterThan(0);
-
-    const reveals = rules.filter(
-      (r) => r.text.includes('.play') && /opacity:\s*1/.test(r.text),
-    );
-
-    expect(reveals.length).toBeGreaterThan(0);
-
-    for (const rule of reveals) {
-      expect(rule.condition).toMatch(/hover:\s*hover/);
-      expect(rule.condition).toMatch(/pointer:\s*fine/);
-    }
-  });
-
-  it('is display:none rather than transparent where it is absent', async () => {
-    const el = await fixture('home-view', {});
-
-    // opacity:0 alone would leave a button that still takes taps and is
-    // still in the accessibility tree, so a phone would keep the hit
-    // area for a control it can never see.
-    const unconditional = rulesOf(el).filter(
-      (r) => r.condition === null && r.text.startsWith('.play'),
-    );
-
-    expect(unconditional.length).toBeGreaterThan(0);
-    expect(unconditional.some((r) => /display:\s*none/.test(r.text))).toBe(true);
-  });
-});