refactor: isolate playback and upload use cases

services/api/internal/wave/onboarding.go

@@ -61,7 +61,7 @@ func (h *Handler) GetOnboarding(ctx context.Context, _ gen.GetOnboardingRequestO
 		artists = append(artists, a)
 	}
 	rows.Close()
-	dto := h.dto()
+	dto := h.dto
 	for _, a := range artists {
 		item := struct {
 			CoverColors []string  `json:"cover_colors"`

services/api/internal/wave/wave.go

@@ -139,14 +139,14 @@ type Handler struct {
 	pool    *pgxpool.Pool
 	rec     *Recommender
 	catalog *library.Store
-	dto     func() library.DTO
+	dto     library.DTO
 	log     *slog.Logger
 	// Warm заранее готовит транскоды выданной пачки (docs/playback.md).
 	Warm func(ctx context.Context, trackIDs []uuid.UUID)
 }
 
 // NewHandler создаёт обработчик.
-func NewHandler(pool *pgxpool.Pool, rec *Recommender, catalog *library.Store, dto func() library.DTO, log *slog.Logger) *Handler {
+func NewHandler(pool *pgxpool.Pool, rec *Recommender, catalog *library.Store, dto library.DTO, log *slog.Logger) *Handler {
 	return &Handler{pool: pool, rec: rec, catalog: catalog, dto: dto, log: log}
 }
 
@@ -323,7 +323,7 @@ func (h *Handler) serve(ctx context.Context, s session, fb []Feedback) (gen.Wave
 	if err != nil {
 		return gen.WaveBatch{}, err
 	}
-	tracks, err := h.dto().Tracks(ctx, rows)
+	tracks, err := h.dto.Tracks(ctx, rows)
 	if err != nil {
 		return gen.WaveBatch{}, err
 	}