fix(service): forward all TuneIn stream candidates for failover

TuneIn's Tune.ashx returns several stream URLs per station (different
bitrates/CDNs) so a speaker can fail over when one is dead. TuneInPlayback
parsed the full list but forwarded only urls[0], wrapping a single URL in
the audio.streams[] array. When TuneIn listed a dead variant first (e.g.
station s56857 / NDR 2 Niedersachsen, whose aac/low 404s while mp3/128
plays), the speaker had no fallback and dead-ended retrying the 404.

Add BuildCustomStreamResponseFromURLs to emit one Stream per candidate in
provider order (top-level StreamUrl mirrors urls[0] for compatibility),
have the single-URL BuildCustomStreamResponse delegate to it, and forward
the full slice from TuneInPlayback. The other single-URL callers
(PlayCustomStream, the custom-stream handler) are unchanged.

Confirmed on real hardware: the speaker now fails over from the 404'd
aac/low to the working mp3/128 stream and plays.

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

pkg/service/bmx/bmx.go

@@ -6,6 +6,7 @@ package bmx
 import (
 	"encoding/base64"
 	"encoding/json"
+	"fmt"
 	"net/url"
 
 	"github.com/gesellix/bose-soundtouch/pkg/models"
@@ -36,20 +37,28 @@ func BuildOrionLocation(serviceURL, name, imageURL, streamURL string) string {
 	return serviceURL + "/core02/svc-bmx-adapter-orion/prod/orion/station?data=" + encoded
 }
 
-// BuildCustomStreamResponse builds a playback response from streamUrl, imageUrl, and name.
-func BuildCustomStreamResponse(streamURL, imageURL, name string) (*models.BmxPlaybackResponse, error) {
-	streamList := []models.Stream{
-		{
+// BuildCustomStreamResponseFromURLs wraps one or more candidate stream URLs
+// in a playback response. The speaker fails over between entries in the
+// Streams array, so order matters — pass them as the provider listed them.
+// The top-level StreamUrl mirrors urls[0] for compatibility.
+func BuildCustomStreamResponseFromURLs(urls []string, imageURL, name string) (*models.BmxPlaybackResponse, error) {
+	if len(urls) == 0 {
+		return nil, fmt.Errorf("no stream URLs provided")
+	}
+
+	streamList := make([]models.Stream, 0, len(urls))
+	for _, u := range urls {
+		streamList = append(streamList, models.Stream{
 			HasPlaylist: true,
 			IsRealtime:  true,
-			StreamUrl:   streamURL,
-		},
+			StreamUrl:   u,
+		})
 	}
 
 	audio := models.Audio{
 		HasPlaylist: true,
 		IsRealtime:  true,
-		StreamUrl:   streamURL,
+		StreamUrl:   urls[0],
 		Streams:     streamList,
 	}
 
@@ -63,6 +72,11 @@ func BuildCustomStreamResponse(streamURL, imageURL, name string) (*models.BmxPla
 	return response, nil
 }
 
+// BuildCustomStreamResponse builds a playback response from streamUrl, imageUrl, and name.
+func BuildCustomStreamResponse(streamURL, imageURL, name string) (*models.BmxPlaybackResponse, error) {
+	return BuildCustomStreamResponseFromURLs([]string{streamURL}, imageURL, name)
+}
+
 // PlayCustomStream builds a playback response from a base64-encoded JSON blob
 // with fields streamUrl, imageUrl, and name.
 func PlayCustomStream(data string) (*models.BmxPlaybackResponse, error) {

pkg/service/bmx/bmx_test.go

@@ -29,3 +29,46 @@ func TestPlayCustomStream(t *testing.T) {
 		t.Errorf("Expected name Stream Name, got %s", resp.Name)
 	}
 }
+
+func TestBuildCustomStreamResponseFromURLs(t *testing.T) {
+	// Multiple candidates must all reach the speaker, in order, so it can
+	// fail over from a dead variant to a working one (see s56857 / NDR 2).
+	urls := []string{
+		"https://example.com/aac/low",
+		"https://example.com/mp3/128/stream.mp3",
+	}
+
+	resp, err := BuildCustomStreamResponseFromURLs(urls, "image.png", "NDR 2")
+	if err != nil {
+		t.Fatalf("BuildCustomStreamResponseFromURLs failed: %v", err)
+	}
+
+	if got := len(resp.Audio.Streams); got != len(urls) {
+		t.Fatalf("expected %d streams, got %d", len(urls), got)
+	}
+
+	for i, want := range urls {
+		if got := resp.Audio.Streams[i].StreamUrl; got != want {
+			t.Errorf("stream %d: expected %q, got %q", i, want, got)
+		}
+	}
+
+	if resp.Audio.StreamUrl != urls[0] {
+		t.Errorf("top-level StreamUrl: expected %q, got %q", urls[0], resp.Audio.StreamUrl)
+	}
+
+	// Empty input is an error, not a panic.
+	if _, err := BuildCustomStreamResponseFromURLs(nil, "", ""); err == nil {
+		t.Error("expected error for empty URL list, got nil")
+	}
+
+	// The single-URL wrapper still yields exactly one stream.
+	single, err := BuildCustomStreamResponse("https://example.com/only", "", "Solo")
+	if err != nil {
+		t.Fatalf("BuildCustomStreamResponse failed: %v", err)
+	}
+
+	if got := len(single.Audio.Streams); got != 1 {
+		t.Errorf("expected 1 stream from single-URL builder, got %d", got)
+	}
+}

pkg/service/bmx/tunein.go

@@ -808,7 +808,7 @@ func TuneInPlayback(stationID, formats string) (*models.BmxPlaybackResponse, err
 
 	name, logo, _ := TuneInDescribeMeta(stationID)
 
-	return BuildCustomStreamResponse(urls[0], logo, name)
+	return BuildCustomStreamResponseFromURLs(urls, logo, name)
 }
 
 // TuneInPodcastInfo returns info for a TuneIn podcast.