[haozhi-liao]

Adds shopify.appEvents.emit(eventHandle, attributes?) to the Checkout standard and address-autocomplete APIs and the Customer Account standard API. emit resolves with {success: true} once the host accepts the event, or {success: false, error} when it was not sent.

Background

App Events let an app record what happens in its UI extensions without a request to the app's backend. Shopify adds the app, shop and extension to each event, and the events show in the app's Dev Dashboard logs next to the events the app sends from its backend with the App Events API.

Host implementations (shop/world, stacked):

• Checkout: #2267719 to #2267724. The API is in #2267720.
• Customer Account: #2267725 to #2267737. The API is in #2267726.

Guides on shopify.dev: #2263577 (Checkout) and #2263578 (Customer Account).

Solution

• New types in checkout/api/standard/standard.ts: AppEvents, AppEventEmitResult, AppEventAttributes and AppEventAttributeValue (string | number | boolean). Customer Account re-exports them from there, as it does SubscribableSignalLike.
• appEvents is required on Checkout StandardApi, Checkout AddressAutocompleteStandardApi and Customer Account StandardApi, so Customer Account order-status targets get it too. Both hosts always expose it on 2027-01. When the feature is off for a shop, emit resolves with {success: false} instead of the property being missing.
• {success: true} means the host accepted the event. It may still wait for analytics consent, and it does not confirm delivery. {success: false, error} covers everything the host rejects: invalid handle or attributes, rate limit, buyer data in attributes, and a disabled host such as the checkout editor. emit never rejects.
• These types match the hosts' own copies: the checkout-web in-repo package in #2267720 and customer-account-web's app-events.ts.
• @shopify/ui-extensions-tester: the Checkout and Customer Account mocks return {success: true}.

🎩

• Merged onto 2027-01-rc (ee50e202a) locally: yarn type-check, yarn lint and yarn test pass.
• Host behavior (validation, consent, limits, drops) is tested in the shop/world PRs above.

Checklist

• I have 🎩'd these changes
• I have updated relevant documentation (the guides are separate shop/world PRs, linked above)

[kumar303]

Some suggestions for making the API docs more clear to partners

[kumar303]

Looks good but I think you're waiting until 2027-01-rc exists so you can merge it there, right? In any case, this same patch can be applied there.

[kristianpd]

/snapit