diff --git a/internal/chain/service.go b/internal/chain/service.go
index ef75e4a..111128d 100644
--- a/internal/chain/service.go
+++ b/internal/chain/service.go
@@ -34,6 +34,8 @@ func (s *Service) SetUserResolver(fn func(username string) (uint, error)) {
 }
 
 // resolveUsername converts a username to the user's on-chain pubKeyHex.
+// If the user exists but has no wallet (e.g. legacy user or failed creation),
+// a wallet is auto-created on the fly.
 func (s *Service) resolveUsername(username string) (string, error) {
 	if s.userResolver == nil {
 		return "", fmt.Errorf("user resolver not configured")
@@ -44,7 +46,17 @@ func (s *Service) resolveUsername(username string) (string, error) {
 	}
 	uw, err := s.repo.FindByUserID(userID)
 	if err != nil {
-		return "", fmt.Errorf("wallet not found")
+		// 지갑이 없으면 자동 생성 시도
+		uw, err = s.CreateWallet(userID)
+		if err != nil {
+			// unique constraint 위반 — 다른 고루틴이 먼저 생성 완료
+			uw, err = s.repo.FindByUserID(userID)
+			if err != nil {
+				return "", fmt.Errorf("wallet auto-creation failed: %w", err)
+			}
+		} else {
+			log.Printf("INFO: auto-created wallet for userID=%d (username=%s)", userID, username)
+		}
 	}
 	return uw.PubKeyHex, nil
 }