refactor(bom): enforce canonical lot_mappings persistence

internal/handlers/vendor_spec.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"net/http"
+	"strings"
 
 	"git.mchus.pro/mchus/quoteforge/internal/localdb"
 	"git.mchus.pro/mchus/quoteforge/internal/repository"
@@ -69,6 +70,13 @@ func (h *VendorSpecHandler) PutVendorSpec(c *gin.Context) {
 		if body.VendorSpec[i].SortOrder == 0 {
 			body.VendorSpec[i].SortOrder = (i + 1) * 10
 		}
+		// Persist canonical LOT mapping only.
+		body.VendorSpec[i].LotMappings = normalizeLotMappings(body.VendorSpec[i].LotMappings)
+		body.VendorSpec[i].ResolvedLotName = ""
+		body.VendorSpec[i].ResolutionSource = ""
+		body.VendorSpec[i].ManualLotSuggestion = ""
+		body.VendorSpec[i].LotQtyPerPN = 0
+		body.VendorSpec[i].LotAllocations = nil
 	}
 
 	spec := localdb.VendorSpec(body.VendorSpec)
@@ -85,6 +93,39 @@ func (h *VendorSpecHandler) PutVendorSpec(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"vendor_spec": spec})
 }
 
+func normalizeLotMappings(in []localdb.VendorSpecLotMapping) []localdb.VendorSpecLotMapping {
+	if len(in) == 0 {
+		return nil
+	}
+	merged := make(map[string]int, len(in))
+	order := make([]string, 0, len(in))
+	for _, m := range in {
+		lot := strings.TrimSpace(m.LotName)
+		if lot == "" {
+			continue
+		}
+		qty := m.QuantityPerPN
+		if qty < 1 {
+			qty = 1
+		}
+		if _, exists := merged[lot]; !exists {
+			order = append(order, lot)
+		}
+		merged[lot] += qty
+	}
+	out := make([]localdb.VendorSpecLotMapping, 0, len(order))
+	for _, lot := range order {
+		out = append(out, localdb.VendorSpecLotMapping{
+			LotName:       lot,
+			QuantityPerPN: merged[lot],
+		})
+	}
+	if len(out) == 0 {
+		return nil
+	}
+	return out
+}
+
 // ResolveVendorSpec resolves vendor PN → LOT without modifying the cart.
 // POST /api/configs/:uuid/vendor-spec/resolve
 func (h *VendorSpecHandler) ResolveVendorSpec(c *gin.Context) {