[vsem-azamat]

Problem

wolt checkout (and wolt_checkout_preview over MCP) fails for a Tesco Hypermarket basket in Prague:

WOLT_CHECKOUT_PAYLOAD_ERROR: unable to resolve category_id for basket item "1dfd4b067979bfe1b97d9236"

For this venue:

• the item page (order-xp/web/v1/pages/venue/<id>/item/<item>) returns {"id": …, "venue_id": …, "sections": []}, with no category;
• the items lookup (POST …/assortment/items with item_ids) returns the mapping only as categories: [{"id": "0ff8ad8c…", "item_ids": ["1dfd4b06…"]}], and the item records have no category field;
• the search fallback queries the basket line name. That name is localized (English, Franz Josef Kaiser Exclusive Green Olives Stuffed with Blue Cheese Paste 300g) while the venue catalog is Czech, so the search finds nothing.

Build searched the items-lookup payload item by item through resolveCheckoutCategoryIDFromCatalogPayload, which only reads fields on the item. Its categories[].item_ids mapping was never indexed. Items whose name search happened to match still worked; in the same basket the cucumber resolved and the olives did not.

Fix

Run buildCheckoutCategoryIDIndex over the items-lookup payloads too: the caller-supplied current catalog and any fetched lookup. This is the same treatment the item page, search and venue content payloads already get. The category then resolves from the lookup that is already made, without the extra search.

Tests

• New TestBuildResolvesCategoryFromCatalogItemsCategoryList uses the real payload shapes: an empty item page, a lookup with categories[].item_ids only, and a search that finds nothing. It fails on main with the same unable to resolve category_id error and passes with the fix. It also asserts that no search request is needed.
• go build ./..., version check, golangci-lint run (v2.4.0 config, 0 issues), go test ./... and go test -race ./... all pass.
• Live: with the patch, wolt checkout --venue-id 6539247b9eecd6092fb9e117 returns a preview for the 17-line basket that failed before.

[mekedron]

Thanks! Reviewed and verified locally:

• The new test fails on main with the same unable to resolve category_id error and passes with the fix.
• Precedence is unchanged where it matters: category fields on the basket line and the item page still win, and the assortment index is merged first, so the lookup mapping only fills gaps.
• Full pre-push gate (build, version check, golangci-lint, go test, go test -race) and the read-only live smoke pass.

[mekedron]

Thanks a lot for the fix and for such a clear write-up, @vsem-azamat! The real payload shapes in the test and the live check made this an easy review. It's merged and shipped in v2.5.1.

Also thanks for digging into the multi-count pricing in #59. I'll take that one in a separate PR, so no need to open one for it.