i

pkg/inventory/redis_reservation_service.go

@@ -3,6 +3,7 @@ package inventory
 import (
 	"context"
 	"fmt"
+	"strconv"
 	"time"
 
 	"github.com/redis/go-redis/v9"
@@ -151,6 +152,75 @@ func (s *RedisCartReservationService) GetReservationSummary(ctx context.Context,
 	}, nil
 }
 
+// GetReservationDetail returns the full per-cart reservation detail for a
+// SKU+location. Unlike GetReservationSummary (which returns only aggregates),
+// this method fetches every active (non-expired) row from Redis and returns
+// a ReservationDetailResponse containing the adjusted summary + per-cart lines.
+// Expired rows are filtered out so the UI only sees live holds. The two Redis
+// fetches (HGetAll + ZRangeWithScores) run sequentially — for an infrequent
+// admin endpoint the goroutine+channel overhead is not worth the latency win.
+func (s *RedisCartReservationService) GetReservationDetail(ctx context.Context, sku SKU, locationID LocationID) (*ReservationDetailResponse, error) {
+	qtyKey := cartQtyKey(sku, locationID)
+	expKey := cartExpKey(sku, locationID)
+
+	// Fetch all cart→qty pairs.
+	qtyMap, err := s.client.HGetAll(ctx, qtyKey).Result()
+	if err != nil {
+		return nil, err
+	}
+
+	// Fetch all cart→expiry pairs.
+	expPairs, err := s.client.ZRangeWithScores(ctx, expKey, 0, -1).Result()
+	if err != nil {
+		return nil, err
+	}
+
+	// Index expiry by cartId.
+	expMap := make(map[string]time.Time, len(expPairs))
+	for _, z := range expPairs {
+		key, ok := z.Member.(string)
+		if !ok {
+			continue
+		}
+		expMap[key] = time.Unix(int64(z.Score), 0)
+	}
+
+	// Build the line list, skipping expired entries.
+	now := time.Now()
+	var lines []ReservationDetailLine
+	var earliestRelease time.Time
+	for cartID, qtyStr := range qtyMap {
+		expiresAt, hasExp := expMap[cartID]
+		if !hasExp || expiresAt.Before(now) {
+			continue
+		}
+		qty, _ := strconv.ParseUint(qtyStr, 10, 32)
+
+		lines = append(lines, ReservationDetailLine{
+			CartID:    cartID,
+			Quantity:  uint32(qty),
+			ExpiresAt: expiresAt,
+		})
+		if earliestRelease.IsZero() || expiresAt.Before(earliestRelease) {
+			earliestRelease = expiresAt
+		}
+	}
+
+	remainingItems, err := s.Available(ctx, sku, locationID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &ReservationDetailResponse{
+		Summary: &ReservationSummary{
+			ReservationCount: int64(len(lines)),
+			EarliestRelease:  earliestRelease,
+			RemainingItems:   remainingItems,
+		},
+		Lines: lines,
+	}, nil
+}
+
 // Available satisfies inventory.ReservationPolicy (platform/inventory).
 // Method renamed from GetAvailableInventory as part of cut-30.x: land the
 // ReservationPolicy interface seam — see docs/inventory-shape.md.

pkg/inventory/request_types.go

@@ -35,3 +35,21 @@ type ReservationSummary struct {
 	EarliestRelease  time.Time `json:"earliest_release"`
 	RemainingItems   int64     `json:"remaining_items"`
 }
+
+// ReservationDetailLine is one row of the per-cart reservation detail,
+// returned by GetReservationDetail when the HTTP caller sets ?detail=true.
+// Expired reservations (expires_at in the past) are filtered out — the
+// list shows only active holds.
+type ReservationDetailLine struct {
+	CartID    string    `json:"cart_id"`
+	Quantity  uint32    `json:"quantity"`
+	ExpiresAt time.Time `json:"expires_at"`
+}
+
+// ReservationDetailResponse is the wire shape when ?detail=true on
+// GET /reservations/{sku}/{locationId}. Carries the aggregate summary
+// alongside the per-cart lines so the UI can show both in one fetch.
+type ReservationDetailResponse struct {
+	Summary *ReservationSummary    `json:"summary"`
+	Lines   []ReservationDetailLine `json:"lines"`
+}