fix(t231): expose freight preflight errors

backend-api/internal/usecase/freight_service.go

@@ -294,13 +294,14 @@ func (service *FreightService) ensureSource(ctx context.Context) error {
 		return nil
 	}
 	if err := preflight.EnsureAuthenticated(ctx); err != nil {
+		code := freightSourceErrorCode(err)
 		result := newError(
 			ErrorKindUnavailable,
-			freightSourceErrorCode(err),
-			"freight source session is unavailable",
+			code,
+			freightPreflightMessage(code),
 			err,
 		)
-		result.Retryable = true
+		result.Retryable = code == "OCR_SERVICE_INVALID" || code == "ERP_UNAVAILABLE"
 		return result
 	}
 	return nil
@@ -709,11 +710,28 @@ func freightSourceErrorCode(err error) string {
 		return "ERP_RESPONSE_INVALID"
 	case errors.Is(err, domain.ErrFreightSourceOCRInvalid):
 		return "OCR_SERVICE_INVALID"
+	case errors.Is(err, domain.ErrFreightSourceLoginRejected):
+		return "ERP_LOGIN_REJECTED"
 	default:
 		return "ERP_UNAVAILABLE"
 	}
 }
 
+func freightPreflightMessage(code string) string {
+	switch code {
+	case "ERP_NOT_CONFIGURED":
+		return "ERP credentials are not configured"
+	case "ERP_LOGIN_REJECTED":
+		return "ERP login was rejected"
+	case "ERP_RESPONSE_INVALID":
+		return "ERP response is invalid"
+	case "OCR_SERVICE_INVALID":
+		return "OCR service is invalid"
+	default:
+		return "ERP is temporarily unavailable"
+	}
+}
+
 func validExternalID(value string) (string, bool) {
 	value = strings.TrimSpace(value)
 	number, err := strconv.ParseUint(value, 10, 64)