feat: notifications say what changed and alert once: a grouped notice names the tracks, grows without re-alerting, and a phone pile lists its titles (M542 #6146-#6151)

- An update to a grouped notice keeps its arrival time and email state, so the
  phone and the email no longer go off again each time it grows.
- Notices carry the names of what changed (newest ten), shown as three and
  "and N more": tracks still missing after the scan's move/replacement fold,
  duplicate groups new to a sweep, songs merged automatically, and the track
  and listener a playback error was for.
- Duplicates found counts only the groups new to that sweep; playback errors
  count reports, not the unresolved total.
- A scan failure says what stopped and links to Admin > Library.
- Android: a pile of more than three alerts lists the newest five titles.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/library/notify_test.go

@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/jackc/pgx/v5/pgtype"
 	"github.com/jackc/pgx/v5/pgxpool"
 
 	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
@@ -36,6 +37,7 @@ type notice struct {
 	kind  string
 	count int64
 	body  string
+	items []string
 }
 
 func unreadNotices(t *testing.T, pool *pgxpool.Pool, user dbq.User) []notice {
@@ -55,7 +57,7 @@ func unreadNotices(t *testing.T, pool *pgxpool.Pool, user dbq.User) []notice {
 		if err := json.Unmarshal(r.Payload, &p); err != nil {
 			t.Fatalf("payload: %v", err)
 		}
-		out = append(out, notice{kind: r.Kind, count: p.Count, body: p.Detail})
+		out = append(out, notice{kind: r.Kind, count: p.Count, body: p.Detail, items: p.Items})
 	}
 	return out
 }
@@ -86,31 +88,70 @@ func TestNotifyScanFinished_FailuresCoalesceAndShutdownIsSilent(t *testing.T) {
 	}
 }
 
-func TestReconcileMissing_NotifiesAdminsWithARunningCount(t *testing.T) {
+// M542: reconcile only records what it marked. The scan tells admins after
+// it has adopted moves and folded replacements, so a file it marked and then
+// healed is never reported as lost.
+func TestReconcileMissing_RecordsTheMarksWithoutNotifying(t *testing.T) {
 	pool := newPool(t)
 	admin := notifyingAdmin(t, pool)
 	s := testScanner(t, populatedRoot(t))
 
-	// Two scans, each losing 2 of 10 tracks (under the mark cap).
-	for pass := 0; pass < 2; pass++ {
-		rows := make([]dbq.ListTrackPathsForReconcileRow, 0, 10)
-		seen := map[string]struct{}{}
-		for i := 0; i < 10; i++ {
-			p := fmt.Sprintf("/music/pass-%d-%02d.mp3", pass, i)
-			rows = append(rows, row(byte(pass*10+i), p, false))
-			if i >= 2 {
-				seen[p] = struct{}{}
-			}
-		}
-		var stats Stats
-		if err := s.reconcileMissing(context.Background(), &fakeReconciler{rows: rows}, seen, &stats); err != nil {
-			t.Fatalf("reconcile pass %d: %v", pass, err)
+	rows := make([]dbq.ListTrackPathsForReconcileRow, 0, 10)
+	seen := map[string]struct{}{}
+	for i := 0; i < 10; i++ {
+		p := fmt.Sprintf("/music/%02d.mp3", i)
+		rows = append(rows, row(byte(i), p, false))
+		if i >= 2 {
+			seen[p] = struct{}{}
 		}
 	}
+	var stats Stats
+	if err := s.reconcileMissing(context.Background(), &fakeReconciler{rows: rows}, seen, &stats); err != nil {
+		t.Fatalf("reconcile: %v", err)
+	}
+	if len(stats.marked) != 2 {
+		t.Errorf("marked %d tracks; want the 2 the walk did not see", len(stats.marked))
+	}
+	if got := unreadNotices(t, pool, admin); len(got) != 0 {
+		t.Fatalf("reconcile notified before the scan could heal anything: %+v", got)
+	}
+}
 
+func TestNotifyStillMissing_NamesOnlyTheTracksStillGone(t *testing.T) {
+	pool := newPool(t)
+	admin := notifyingAdmin(t, pool)
+	ctx := context.Background()
+	q := dbq.New(pool)
+	dir := t.TempDir()
+	first, album, artist := seedTrack(t, pool, filepath.Join(dir, "a.mp3"))
+	second, err := q.UpsertTrack(ctx, dbq.UpsertTrackParams{
+		Title: "Another Track", AlbumID: album.ID, ArtistID: artist.ID,
+		DurationMs: 1000, FilePath: filepath.Join(dir, "b.mp3"), FileSize: 100, FileFormat: "mp3",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	// The scan marked both; the second came back (a move it adopted).
+	marked := []pgtype.UUID{first.ID, second.ID}
+	if _, err := q.MarkTracksMissing(ctx, []pgtype.UUID{first.ID}); err != nil {
+		t.Fatal(err)
+	}
+
+	s := New(pool, slog.New(slog.NewTextHandler(io.Discard, nil)), nil, nil)
+	s.notifyStillMissing(ctx, marked)
 	got := unreadNotices(t, pool, admin)
-	if len(got) != 1 || got[0].kind != string(notifications.KindTracksMissing) || got[0].count != 4 {
-		t.Fatalf("notices = %+v, want one tracks_missing counting 4", got)
+	if len(got) != 1 || got[0].kind != string(notifications.KindTracksMissing) || got[0].count != 1 ||
+		len(got[0].items) != 1 || got[0].items[0] != "Delete Test Artist – Delete Test Track" {
+		t.Fatalf("notices = %+v, want one tracks_missing naming the one track still gone", got)
+	}
+
+	// Nothing still gone: nothing to say.
+	if _, err := q.MarkAllNotificationsRead(ctx, dbq.MarkAllNotificationsReadParams{UserID: admin.ID}); err != nil {
+		t.Fatal(err)
+	}
+	s.notifyStillMissing(ctx, []pgtype.UUID{second.ID})
+	if got := unreadNotices(t, pool, admin); len(got) != 0 {
+		t.Fatalf("a healed track was reported: %+v", got)
 	}
 }
 
@@ -159,8 +200,9 @@ func TestDuplicateSweep_NotifiesOnlyWhenSomethingNewIsProposed(t *testing.T) {
 	pair("first", 1, 100)
 	sweep()
 	got := unreadNotices(t, pool, admin)
-	if len(got) != 1 || got[0].kind != string(notifications.KindDuplicatesFound) || got[0].count != 1 {
-		t.Fatalf("after the first sweep notices = %+v, want one duplicates_found counting 1", got)
+	if len(got) != 1 || got[0].kind != string(notifications.KindDuplicatesFound) || got[0].count != 1 ||
+		len(got[0].items) != 1 || got[0].items[0] != "Delete Test Artist – first" {
+		t.Fatalf("after the first sweep notices = %+v, want one duplicates_found naming the first pair", got)
 	}
 
 	// Read, then swept again with nothing new: no reminder.
@@ -170,11 +212,11 @@ func TestDuplicateSweep_NotifiesOnlyWhenSomethingNewIsProposed(t *testing.T) {
 		t.Fatalf("a sweep that found nothing new notified: %+v", got)
 	}
 
-	// A new pair is news, and the count is everything awaiting review.
+	// A new pair is news, and the notice is about it alone: the first was read.
 	pair("second", 2, 200)
 	sweep()
 	got = unreadNotices(t, pool, admin)
-	if len(got) != 1 || got[0].count != 2 {
-		t.Fatalf("after a new pair notices = %+v, want one counting 2", got)
+	if len(got) != 1 || got[0].count != 1 || len(got[0].items) != 1 || got[0].items[0] != "Delete Test Artist – second" {
+		t.Fatalf("after a new pair notices = %+v, want one naming only the new pair", got)
 	}
 }