fix(datastore): dedup recents by ID in SaveRecents (stop same-recent pile-up)

A speaker<->marge recents sync could re-store the same recent (same ID) multiple
times — observed live as one STORED_MUSIC track appearing 4x in the speaker's
/recents, the service's stored Recents.xml, and /full. The duplicates crowd the
capped (10) recents list and evict other sources (e.g. a freshly played Spotify
track never appears). SaveConfiguredSources already dedups by ID; SaveRecents did
not, so dupes introduced by any path (AddRecent move-to-front, syncRecents from
the speaker's /full, setup/health) persisted and fed back through the sync loop.

SaveRecents now dedups by ID (first occurrence wins) at the single chokepoint all
callers share, so the list self-heals on the next write. Regression test added.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pkg/service/datastore/datastore.go

@@ -1436,6 +1436,27 @@ func (ds *DataStore) SaveRecents(account, device string, recents []models.Servic
 		Recents []RecentXML `xml:"recent"`
 	}
 
+	// Deduplicate by ID before saving; first occurrence wins. A speaker<->marge
+	// recents sync can otherwise re-store the same recent (same ID) multiple
+	// times — it then crowds the capped list and evicts other sources from the
+	// speaker's recents. Mirrors SaveConfiguredSources.
+	seen := make(map[string]bool)
+	deduped := make([]models.ServiceRecent, 0, len(recents))
+
+	for i := range recents {
+		if id := recents[i].ID; id != "" {
+			if seen[id] {
+				continue
+			}
+
+			seen[id] = true
+		}
+
+		deduped = append(deduped, recents[i])
+	}
+
+	recents = deduped
+
 	wrap := RecentsXML{
 		Recents: make([]RecentXML, 0, len(recents)),
 	}

pkg/service/datastore/recents_dedup_test.go

@@ -0,0 +1,67 @@
+package datastore
+
+import (
+	"os"
+	"testing"
+
+	"github.com/gesellix/bose-soundtouch/pkg/models"
+)
+
+// TestSaveRecents_DeduplicatesByID is a regression test for the recents
+// duplication bug: a speaker<->marge sync could re-store the same recent (same
+// ID) multiple times, crowding the capped list and evicting other sources from
+// the speaker's recents. SaveRecents must dedup by ID (first occurrence wins).
+func TestSaveRecents_DeduplicatesByID(t *testing.T) {
+	tmp, err := os.MkdirTemp("", "recents-dedup-*")
+	if err != nil {
+		t.Fatalf("temp dir: %v", err)
+	}
+
+	defer func() { _ = os.RemoveAll(tmp) }()
+
+	ds := NewDataStore(tmp)
+	account, device := "6919733", "A81B6A536A98"
+
+	mk := func(id, name string) models.ServiceRecent {
+		var r models.ServiceRecent
+		r.ID = id
+		r.Name = name
+		r.Source = "7"
+		r.SourceAccount = "4d696e69-444c-164e-9d41-72ecda78e4c1/0"
+		r.Location = "1$4$2 TRACK"
+
+		return r
+	}
+
+	// Same ID four times (the observed live state), plus two distinct recents.
+	in := []models.ServiceRecent{
+		mk("260614006", "03 - Salvation"),
+		mk("260614006", "03 - Salvation"),
+		mk("260614006", "03 - Salvation"),
+		mk("260614006", "03 - Salvation"),
+		mk("260614004", "06 - Back Burner"),
+		mk("260613001", "Artifact"),
+	}
+
+	if err := ds.SaveRecents(account, device, in); err != nil {
+		t.Fatalf("SaveRecents: %v", err)
+	}
+
+	out, err := ds.GetRecents(account, device)
+	if err != nil {
+		t.Fatalf("GetRecents: %v", err)
+	}
+
+	counts := map[string]int{}
+	for _, r := range out {
+		counts[r.ID]++
+	}
+
+	if counts["260614006"] != 1 {
+		t.Errorf("duplicate recent not deduped: id 260614006 appears %d times (want 1)", counts["260614006"])
+	}
+
+	if len(out) != 3 {
+		t.Errorf("expected 3 distinct recents, got %d: %+v", len(out), counts)
+	}
+}