第 4 阶段：订单、交接与账务--ok

backend/internal/modules/wallet/service.go

@@ -0,0 +1,27 @@
+package wallet
+
+import "errors"
+
+var ErrDependencyUnavailable = errors.New("dependency unavailable")
+
+type Service struct {
+	repo *Repository
+}
+
+func NewService(repo *Repository) *Service {
+	return &Service{repo: repo}
+}
+
+func (s *Service) Account(userID uint64) (*AccountDTO, error) {
+	if s.repo == nil {
+		return nil, ErrDependencyUnavailable
+	}
+	return s.repo.Account(userID)
+}
+
+func (s *Service) Ledger(userID uint64) ([]LedgerDTO, error) {
+	if s.repo == nil {
+		return nil, ErrDependencyUnavailable
+	}
+	return s.repo.Ledger(userID)
+}