internal product index

cmd/cart/projection_overlay.go

@@ -47,6 +47,9 @@ func resolveTaxBp(class string) int {
 //	                  quietly swapping in a default 2500 and miscategorising)
 //	Title          (canonical, post-trim)
 //	Image          (canonical)
+//	ItemID         (positive bus values override HTTP; zero is the
+//	                  documented "no id" signal, so a tombstone's zero or an
+//	                  unbus-fed cache value won't clobber a real HTTP id.)
 //	InventoryTracked (only flips to true; false is the zero value in proto
 //	                  and may be unset on the wire, so we don't second-guess)
 //	DropShip       (only flips to true; same reasoning)
@@ -54,12 +57,14 @@ func resolveTaxBp(class string) int {
 // The HTTP-fetched values remain authoritative for fields the cache does not
 // carry: SellerId / SellerName (marketplace split), Stock (per docs/inventory-
 // shape.md stock is queried synchronously from inventory, not cached),
-// OrgPrice / Discount (not yet on the projection schema), the dynamic
+// OrgPrice / Discount (not yet on the projection schema), and the dynamic
 // ExtraJson product data (configurator options — width/height used by
-// accessory child-pricing), and the catalog uint32 ItemId (the product
-// service's integer id which messages.AddItem.ItemId dedupes on — Projection
-// only carries the opaque string ID, so a cache-only build path is blocked
-// and the HTTP fetch is preserved).
+// accessory child-pricing).
+//
+// Now that ItemID round-trips from the bus, a future "cache-only" build path
+// (skipping PRODUCT_BASE_URL entirely for known SKUs) is unblocked — the
+// only fields left HTTP-only in that future path are Sellers, Stock, OrgPrice
+// and configurator extras, none of which affect line dedup.
 //
 // Tombstoned SKUs (catalog.projection_published with deleted=true) → the
 // caller checks idx.IsDeleted(sku) before this helper and short-circuits.
@@ -78,6 +83,12 @@ func ApplyProjectionOverlay(msg *messages.AddItem, p catalog.Projection) {
 	if p.TaxClass != "" {
 		msg.Tax = int32(resolveTaxBp(p.TaxClass))
 	}
+	// ItemId: positive bus values override HTTP. Zero means the producer
+	// didn't publish an id (some sources have no integer id) — we leave the
+	// HTTP-fetched id intact in that case rather than zeroing out a real id.
+	if p.ItemID != 0 {
+		msg.ItemId = p.ItemID
+	}
 	// Display fields: only override if non-empty so the HTTP-fanned value
 	// remains in place when the cache hasn't populated them yet.
 	if p.Title != "" {