diff --git a/backend/internal/service/account.go b/backend/internal/service/account.go
index a6b20d9d..51b7a4f1 100644
--- a/backend/internal/service/account.go
+++ b/backend/internal/service/account.go
@@ -326,17 +326,3 @@ func (a *Account) IsOpenAITokenExpired() bool {
 	}
 	return time.Now().Add(60 * time.Second).After(*expiresAt)
 }
-
-// mergeJSONB merges source map into target map (for preserving extra fields during account sync)
-func mergeJSONB(target, source map[string]any) map[string]any {
-	if target == nil {
-		target = make(map[string]any)
-	}
-	if source == nil {
-		return target
-	}
-	for k, v := range source {
-		target[k] = v
-	}
-	return target
-}
diff --git a/backend/internal/service/crs_sync_service.go b/backend/internal/service/crs_sync_service.go
index fa7bad21..cd1dbcec 100644
--- a/backend/internal/service/crs_sync_service.go
+++ b/backend/internal/service/crs_sync_service.go
@@ -801,11 +801,11 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 			continue
 		}
 
-		existing.Extra = mergeJSONB(existing.Extra, extra)
+		existing.Extra = mergeMap(existing.Extra, extra)
 		existing.Name = defaultName(src.Name, src.ID)
 		existing.Platform = PlatformGemini
 		existing.Type = AccountTypeOAuth
-		existing.Credentials = mergeJSONB(existing.Credentials, credentials)
+		existing.Credentials = mergeMap(existing.Credentials, credentials)
 		if proxyID != nil {
 			existing.ProxyID = proxyID
 		}
@@ -908,11 +908,11 @@ func (s *CRSSyncService) SyncFromCRS(ctx context.Context, input SyncFromCRSInput
 			continue
 		}
 
-		existing.Extra = mergeJSONB(existing.Extra, extra)
+		existing.Extra = mergeMap(existing.Extra, extra)
 		existing.Name = defaultName(src.Name, src.ID)
 		existing.Platform = PlatformGemini
 		existing.Type = AccountTypeApiKey
-		existing.Credentials = mergeJSONB(existing.Credentials, credentials)
+		existing.Credentials = mergeMap(existing.Credentials, credentials)
 		if proxyID != nil {
 			existing.ProxyID = proxyID
 		}