feat(products): sort by

internal/contract/category_contract.go

@@ -30,6 +30,7 @@ type ListCategoriesRequest struct {
 	OrganizationID *uuid.UUID `json:"organization_id,omitempty"`
 	OutletID       *uuid.UUID `json:"outlet_id,omitempty"`
 	ParentID       *uuid.UUID `json:"parent_id,omitempty"`
+	Type           string     `json:"type,omitempty" validate:"omitempty,oneof=parent child"`
 	BusinessType   string     `json:"business_type,omitempty"`
 	Search         string     `json:"search,omitempty"`
 	Page           int        `json:"page" validate:"required,min=1"`

internal/handler/category_handler.go

@@ -196,6 +196,13 @@ func (h *CategoryHandler) ListCategories(c *gin.Context) {
 			req.ParentID = &parentID
 		}
 	}
+
+	// type=parent -> top level categories only
+	// type=child  -> leaf categories (sub categories + top level ones without children)
+	if categoryType := c.Query("type"); categoryType != "" {
+		req.Type = categoryType
+	}
+
 	validationError, validationErrorCode := h.categoryValidator.ValidateListCategoriesRequest(req)
 	if validationError != nil {
 		logger.FromContext(ctx).WithError(validationError).Error("CategoryHandler::ListCategories -> request validation failed")

internal/repository/category_repository.go

@@ -63,6 +63,21 @@ func (r *CategoryRepositoryImpl) Delete(ctx context.Context, id uuid.UUID) error
 	return r.db.WithContext(ctx).Delete(&entities.Category{}, "id = ?", id).Error
 }
 
+// applyCategoryTypeFilter narrows the query by position in the category tree.
+//   - "parent": top level categories only (no parent of their own)
+//   - "child":  leaf categories — sub categories plus top level categories that
+//     have no sub categories, i.e. everything a product can be assigned to
+func applyCategoryTypeFilter(query *gorm.DB, value interface{}) *gorm.DB {
+	switch value {
+	case "parent":
+		return query.Where("parent_id IS NULL")
+	case "child":
+		return query.Where("NOT EXISTS (SELECT 1 FROM categories AS sub WHERE sub.parent_id = categories.id)")
+	default:
+		return query
+	}
+}
+
 func (r *CategoryRepositoryImpl) List(ctx context.Context, filters map[string]interface{}, limit, offset int) ([]*entities.Category, int64, error) {
 	var categories []*entities.Category
 	var total int64
@@ -77,6 +92,8 @@ func (r *CategoryRepositoryImpl) List(ctx context.Context, filters map[string]in
 		case "outlet_id":
 			// Include outlet-specific categories AND global categories (outlet_id IS NULL)
 			query = query.Where("outlet_id = ? OR outlet_id IS NULL", value)
+		case "type":
+			query = applyCategoryTypeFilter(query, value)
 		default:
 			query = query.Where(key+" = ?", value)
 		}
@@ -101,6 +118,8 @@ func (r *CategoryRepositoryImpl) Count(ctx context.Context, filters map[string]i
 			query = query.Where("name ILIKE ? OR description ILIKE ?", searchValue, searchValue)
 		case "outlet_id":
 			query = query.Where("outlet_id = ? OR outlet_id IS NULL", value)
+		case "type":
+			query = applyCategoryTypeFilter(query, value)
 		default:
 			query = query.Where(key+" = ?", value)
 		}

internal/repository/product_repository.go

@@ -112,7 +112,9 @@ func (r *ProductRepositoryImpl) List(ctx context.Context, filters map[string]int
 		return nil, 0, err
 	}
 
-	err := query.Limit(limit).Offset(offset).Find(&products).Error
+	// id is a tie-breaker so LIMIT/OFFSET paging stays stable when several products
+	// share the same created_at.
+	err := query.Order("created_at DESC, id DESC").Limit(limit).Offset(offset).Find(&products).Error
 	return products, total, err
 }
 
@@ -265,6 +267,8 @@ func (r *ProductRepositoryImpl) ListWithOutletPrice(ctx context.Context, filters
 		return nil, 0, err
 	}
 
-	err := query.Limit(limit).Offset(offset).Find(&products).Error
+	// Columns are qualified because the outlet join brings a second created_at/id
+	// into scope. id is a tie-breaker for stable LIMIT/OFFSET paging.
+	err := query.Order("products.created_at DESC, products.id DESC").Limit(limit).Offset(offset).Find(&products).Error
 	return products, total, err
 }

internal/service/category_service.go

@@ -94,6 +94,9 @@ func (s *CategoryServiceImpl) ListCategories(ctx context.Context, req *contract.
 	if req.ParentID != nil {
 		filters["parent_id"] = *req.ParentID
 	}
+	if req.Type != "" {
+		filters["type"] = req.Type
+	}
 	if req.Search != "" {
 		filters["search"] = req.Search
 	}

internal/validator/category_validator.go

@@ -118,5 +118,9 @@ func (v *CategoryValidatorImpl) ValidateListCategoriesRequest(req *contract.List
 		}
 	}
 
+	if req.Type != "" && req.Type != "parent" && req.Type != "child" {
+		return errors.New("type must be either 'parent' or 'child'"), constants.MalformedFieldErrorCode
+	}
+
 	return nil, ""
 }