diff --git a/backend/internal/handler/admin/account_codex_import.go b/backend/internal/handler/admin/account_codex_import.go
index 59fe30a0..c5fcfd1d 100644
--- a/backend/internal/handler/admin/account_codex_import.go
+++ b/backend/internal/handler/admin/account_codex_import.go
@@ -211,9 +211,7 @@ func (h *AccountHandler) importCodexSessions(ctx context.Context, req CodexSessi
 			})
 			continue
 		}
-		for _, warning := range expiryWarnings {
-			item.WarningTexts = append(item.WarningTexts, warning)
-		}
+		item.WarningTexts = append(item.WarningTexts, expiryWarnings...)
 		if credentialExpiresAt != nil {
 			item.Credentials["expires_at"] = credentialExpiresAt.Format(time.RFC3339)
 		}
@@ -565,7 +563,7 @@ func normalizeCodexImportEntry(entry codexImportEntry) (*codexImportAccount, err
 	}
 	if item.IDToken != "" {
 		item.Credentials["id_token"] = item.IDToken
-		enrichCodexImportAccountFromJWT(item, item.IDToken, false, now)
+		_ = enrichCodexImportAccountFromJWT(item, item.IDToken, false, now)
 	}
 	if err := enrichCodexImportAccountFromJWT(item, item.AccessToken, true, now); err != nil {
 		return nil, err
diff --git a/backend/internal/service/vertex_service_account.go b/backend/internal/service/vertex_service_account.go
index c7a2279d..256695de 100644
--- a/backend/internal/service/vertex_service_account.go
+++ b/backend/internal/service/vertex_service_account.go
@@ -202,7 +202,11 @@ func newVertexServiceAccountHTTPClient(proxyURL string) (*http.Client, error) {
 	if err != nil {
 		return nil, err
 	}
-	transport := http.DefaultTransport.(*http.Transport).Clone()
+	defaultTransport, ok := http.DefaultTransport.(*http.Transport)
+	if !ok {
+		return nil, fmt.Errorf("unexpected default transport type %T", http.DefaultTransport)
+	}
+	transport := defaultTransport.Clone()
 	transport.Proxy = nil
 	if err := proxyutil.ConfigureTransportProxy(transport, parsedProxy); err != nil {
 		return nil, err