12 March 2026 · Instrumentation
Mapping add_to_cart on Thai marketplace apps
If your storefront is a single merchant, add_to_cart is almost boring. If it is a Thai marketplace binary with wishlists, buy-now, and shop-in-shop bags, one name will lie to you by Friday.
We keep seeing the same dump: a custom event called add_to_cart firing from four UI surfaces. Related-product chips. The heart icon that actually writes to a wishlist table. The “buy this shop’s items” button that opens a second cart object. And the genuine size-selected add on the PDP. Reporting then divides purchases by that soup and calls the result conversion.
Split the intent, keep a parent
The studio rule is not “never reuse a name.” It is “never reuse a name across intents.” Wishlist writes are add_to_wishlist. Shop-in-shop adds carry affiliation or seller_id on the same commerce family, but they must not share a trigger with the primary bag. Buy-now that skips the cart still deserves a documented skip: fire begin_checkout from that tap, and do not invent an add_to_cart just to please a funnel template.
For roll-ups, define a parent measure in the warehouse — something like commerce_add — that unions the genuine bag adds. Campaign dashboards can use the parent. Product critique uses the children. Mixing those grains in one Looker tile is how 11.11 “add rates” become unusable.
Thai UI copy is not the schema
Buttons labelled “ใส่ตะกร้า,” “ซื้อเลย,” and “เก็บไว้ก่อน” do not map 1:1 to English event names, and they should not. Translate the intent in the dictionary, not in the payload. Payload names stay stable ASCII. If a localisation change relabels a button, the event name does not move with it. That sounds obvious until a growth manager asks engineering to rename add_to_cart to match a campaign landing page.
What to bring to critique
A screen recording of PDP, wishlist, and shop-in-shop. The JSON for each tap. A one-line owner for each name. If you cannot say who owns shop-in-shop adds, you are not ready to instrument them. Checkout Event Instrumentation spends most of module 02 on this split; Field Notes includes the worksheet if you are not sitting a live seat.