Add new items section to price changes modal

Track positions added to a pricelist (not present in the previous one)
and display them in a separate "Новые позиции" section in the price
changes modal on both pricelists and admin_pricing pages.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/handlers/pricelist.go

@@ -116,6 +116,7 @@ func (h *PricelistHandler) Create(c *gin.Context) {
 		changes = &pricelist.PriceChangeSummary{
 			Changed: []pricelist.PriceChangeItem{},
 			Missing: []pricelist.PriceChangeItem{},
+			Added:   []pricelist.PriceChangeItem{},
 		}
 	}
 	c.JSON(http.StatusCreated, gin.H{
@@ -182,6 +183,7 @@ func (h *PricelistHandler) CreateWithProgress(c *gin.Context) {
 			changes = &pricelist.PriceChangeSummary{
 				Changed: []pricelist.PriceChangeItem{},
 				Missing: []pricelist.PriceChangeItem{},
+				Added:   []pricelist.PriceChangeItem{},
 			}
 		}
 

internal/services/pricelist/service.go

@@ -51,6 +51,7 @@ type PriceChangeSummary struct {
 	PreviousPricelistVersion string            `json:"previous_pricelist_version,omitempty"`
 	Changed                  []PriceChangeItem `json:"changed"`
 	Missing                  []PriceChangeItem `json:"missing"`
+	Added                    []PriceChangeItem `json:"added"`
 }
 
 func NewService(db *gorm.DB, repo *repository.PricelistRepository, componentRepo *repository.ComponentRepository, pricingSvc *pricing.Service) *Service {
@@ -524,7 +525,7 @@ func (s *Service) StreamItemsForExport(pricelistID uint, batchSize int, callback
 // BuildPriceChangeSummary compares a newly created pricelist with the previous pricelist of the same source.
 func (s *Service) BuildPriceChangeSummary(pricelistID uint) (*PriceChangeSummary, error) {
 	if s.db == nil {
-		return &PriceChangeSummary{Changed: []PriceChangeItem{}, Missing: []PriceChangeItem{}}, nil
+		return &PriceChangeSummary{Changed: []PriceChangeItem{}, Missing: []PriceChangeItem{}, Added: []PriceChangeItem{}}, nil
 	}
 
 	var current models.Pricelist
@@ -539,7 +540,7 @@ func (s *Service) BuildPriceChangeSummary(pricelistID uint) (*PriceChangeSummary
 		First(&previous).Error
 	if err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
-			return &PriceChangeSummary{Changed: []PriceChangeItem{}, Missing: []PriceChangeItem{}}, nil
+			return &PriceChangeSummary{Changed: []PriceChangeItem{}, Missing: []PriceChangeItem{}, Added: []PriceChangeItem{}}, nil
 		}
 		return nil, fmt.Errorf("loading previous pricelist: %w", err)
 	}
@@ -568,8 +569,14 @@ func (s *Service) BuildPriceChangeSummary(pricelistID uint) (*PriceChangeSummary
 		curMap[strings.TrimSpace(it.LotName)] = it.Price
 	}
 
+	prevMap := make(map[string]float64, len(prevItems))
+	for _, it := range prevItems {
+		prevMap[strings.TrimSpace(it.LotName)] = it.Price
+	}
+
 	changed := make([]PriceChangeItem, 0)
 	missing := make([]PriceChangeItem, 0)
+	added := make([]PriceChangeItem, 0)
 	const eps = 0.000001
 	for _, prev := range prevItems {
 		lotName := strings.TrimSpace(prev.LotName)
@@ -606,10 +613,28 @@ func (s *Service) BuildPriceChangeSummary(pricelistID uint) (*PriceChangeSummary
 		})
 	}
 
+	for _, cur := range curItems {
+		lotName := strings.TrimSpace(cur.LotName)
+		if lotName == "" {
+			continue
+		}
+		if _, exists := prevMap[lotName]; !exists {
+			priceCopy := cur.Price
+			added = append(added, PriceChangeItem{
+				LotName:    lotName,
+				OldPrice:   0,
+				NewPrice:   &priceCopy,
+				Diff:       nil,
+				ChangeType: "added",
+			})
+		}
+	}
+
 	return &PriceChangeSummary{
 		PreviousPricelistID:      previous.ID,
 		PreviousPricelistVersion: previous.Version,
 		Changed:                  changed,
 		Missing:                  missing,
+		Added:                    added,
 	}, nil
 }