Protocol-agnostic checkout events for Swift

[markmur]

Stack

Top to bottom:

1. Web: Add protocol-agnostic checkout events for web #766
2. Android: Add protocol-agnostic checkout events for Android #767
3. Swift events (this PR): Protocol-agnostic checkout events for Swift #748
4. Swift protocol namespace: Namespace Swift protocol payloads #777

Summary

• adds a Kit-owned top-level Checkout that preserves every checkout snapshot field except the protocol-only ucp field
• reuses generated Embedded Checkout Protocol domain types directly instead of duplicating them or publishing Kit-prefixed type aliases
• preserves unknown top-level extension fields in additionalProperties; generated nested models retain their own extension fields
• translates ECP start, supported change, and complete notifications through an internal adapter with equal-snapshot deduplication
• exposes concrete CheckoutStartEvent, CheckoutUpdateEvent, CheckoutCompleteEvent, and CheckoutFailureEvent payloads through idiomatic SwiftUI modifiers and UIKit delegate callbacks
• keeps lineItems as a plain array without derived inventory annotations
• maps delegated window-open requests to onLinkClick in SwiftUI and checkoutAction(for:) in UIKit, with .open, .handled, and .cancel policies
• removes public protocol-client injection and the Accelerated Checkouts .connect(client) modifier, and updates the sample to use Kit callbacks
• decodes RFC 3339 dates, including fractional seconds, so shipping-method updates reach onUpdate

Design notes

Checkout is a thin top-level projection of the protocol checkout snapshot. It removes only ucp; attribution, buyer, context, continuation URL, currency, discounts, expiry, fulfillment, ID, line items, links, messages, order, payment, signals, status, totals, and unknown extension fields remain intact. Optional values remain optional, arrays are not synthesized for absent values, and enum values are not coerced to defaults.

The protocol client remains behind the web bridge. The currently supported ECP checkout change notifications—line items, messages, totals, and fulfillment—become the same public CheckoutUpdateEvent. Buyer and payment change notifications are intentionally not registered because Checkout Kit does not support those update sources yet. Registration syntax stays native to SwiftUI and UIKit.

Separate event payload types give each callback room to gain event-specific metadata later without changing the closure or delegate shape. The public checkout snapshot does not infer inventory state from protocol messages.

Window-open requests are similarly abstracted: consumers receive only a validated URL and return a Kit-owned action. .open preserves the default Safari/system behavior, .handled reports success without opening the URL again, and .cancel rejects the request. The default is .open.

The protocol namespace and API comparison ordering fix are supplied by #777.

Validation passed: CocoaPods lint, Swift formatting and lint, 71 Swift protocol tests, 8 checkout adapter tests, and all three public Swift API baseline checks.

[github-actions]

React Native — Coverage Report

Lines	Statements	Branches	Functions
	90.97% (363/399)	87.29% (213/244)	100% (92/92)

[github-actions]

Web — Coverage Report

Lines	Statements	Branches	Functions
	94.46% (290/307)	81.11% (146/180)	98.73% (78/79)

[github-actions]

Package Size

Platform	Artifact	Base	Head	Delta
Web	npm tarball	80.1 KiB	80.1 KiB	0 B
React Native	npm tarball	108.6 KiB	108.6 KiB	0 B
Android	release AAR	366.6 KiB	366.6 KiB	0 B

Web file breakdown

File	Base	Head	Delta
dist/index.js.map	217.7 KiB	217.7 KiB	0 B
dist/custom-elements.json	51.4 KiB	51.4 KiB	0 B
dist/index.d.ts	45.9 KiB	45.9 KiB	0 B
dist/index.js	39.5 KiB	39.5 KiB	0 B
README.md	20.0 KiB	20.0 KiB	0 B
package.json	2.9 KiB	2.9 KiB	0 B
LICENSE	1.1 KiB	1.1 KiB	0 B

React Native file breakdown

File	Base	Head	Delta
node_modules/@shopify/checkout-kit-protocol/src/generated/Models.ts	85.4 KiB	85.4 KiB	0 B
node_modules/@shopify/checkout-kit-protocol/src/generated/Models.d.ts	53.0 KiB	53.0 KiB	0 B
android/src/main/java/com/shopify/reactnative/checkoutkit/ShopifyCheckoutKitModule.java	16.2 KiB	16.2 KiB	0 B
ios/ShopifyCheckoutKit.swift	16.1 KiB	16.1 KiB	0 B
ios/AcceleratedCheckoutButtons.swift	14.1 KiB	14.1 KiB	0 B
src/components/AcceleratedCheckoutButtons.tsx	13.0 KiB	13.0 KiB	0 B
src/index.ts	12.7 KiB	12.7 KiB	0 B
lib/commonjs/index.js	12.4 KiB	12.4 KiB	0 B
lib/commonjs/components/AcceleratedCheckoutButtons.js	11.4 KiB	11.4 KiB	0 B
src/index.d.ts	11.3 KiB	11.3 KiB	0 B
lib/commonjs/components/AcceleratedCheckoutButtons.js.map	10.4 KiB	10.4 KiB	0 B
lib/module/index.js	10.4 KiB	10.4 KiB	0 B
lib/module/components/AcceleratedCheckoutButtons.js	10.2 KiB	10.2 KiB	0 B
node_modules/@shopify/checkout-kit-protocol/src/generated/ProtocolNotifications.ts	9.5 KiB	9.5 KiB	0 B
lib/module/components/AcceleratedCheckoutButtons.js.map	9.1 KiB	9.1 KiB	0 B
lib/module/index.js.map	8.1 KiB	8.1 KiB	0 B
src/present-dispatcher.ts	8.0 KiB	8.0 KiB	0 B
lib/commonjs/index.js.map	7.9 KiB	7.9 KiB	0 B
node_modules/@shopify/checkout-kit-protocol/src/generated/ProtocolNotifications.d.ts	7.6 KiB	7.6 KiB	0 B
node_modules/@shopify/checkout-kit-protocol/src/generated/ProtocolRenameMap.ts	7.2 KiB	7.2 KiB	0 B
…and 117 smaller files

Android file breakdown

File	Base	Head	Delta
classes.jar	390.5 KiB	390.5 KiB	0 B
res/layout/checkout_view_content.xml	2.6 KiB	2.6 KiB	0 B
res/layout/checkout_sheet_content.xml	2.0 KiB	2.0 KiB	0 B
res/values/values.xml	1.3 KiB	1.3 KiB	0 B
R.txt	1.2 KiB	1.2 KiB	0 B
AndroidManifest.xml	922 B	922 B	0 B
proguard.txt	798 B	798 B	0 B
res/drawable/close.xml	431 B	431 B	0 B
res/menu/checkout_menu.xml	354 B	354 B	0 B
META-INF/com/android/build/gradle/aar-metadata.properties	157 B	157 B	0 B

Measured from the PR base SHA and PR head SHA. The file breakdown shows uncompressed sizes within each package artifact, so individual files do not sum to the compressed artifact total. This comment reports package artifact sizes only; it is not a final app binary-size report.

[bitrise]

Install this build

Open Tophat, select your target device, then click Install. Links open on the Mac running Tophat.

SDK	Install
React Native	Install with Tophat
Swift	Install with Tophat
Kotlin	Install with Tophat

Checkout Kit E2E results

Status	Tags	Target	Platform	OS version tag	Device
❌	launch, checkout-presentation, checkout-completion, buyer-identity	react-native	ios	latest	iPhone 15 iOS 27 Beta
✅	launch, checkout-presentation, checkout-completion, buyer-identity	react-native	android	latest	Google Pixel 9 Android 17.0
✅	launch, checkout-presentation, checkout-completion, buyer-identity, preload	kotlin	android	latest	Google Pixel 9 Android 17.0
❌	launch, checkout-presentation, checkout-completion, buyer-identity, preload	swift	ios	latest	iPhone 15 iOS 27 Beta

Failures

Caution

If you believe an assertion is flaky, please raise a ticket in the #checkout-kit-devs channel so it can be addressed.

BrowserStack artifacts require BrowserStack access. Sign in to BrowserStack App Automate before opening artifact links.

iOS — react-native

Test	Status	Artifacts
./tests/shared/checkout-guest	❌	BrowserStack · Video · Screenshot · Maestro commands · Maestro log

iOS — swift

Test	Status	Artifacts
./tests/shared/checkout-hardcoded-buyer-identity	❌	BrowserStack · Video · Screenshot · Maestro commands · Maestro log
./tests/shared/checkout-guest	❌	BrowserStack · Video · Screenshot · Maestro commands · Maestro log

[tiagocandido]

Two README issues I could not attach inline (the lines are outside the diff):

• Line ~351: the Checkout lifecycle section still teaches CheckoutProtocol.Client + present(client:) + .connect, all removed in this PR. Needs a rewrite around the delegate methods and onStart/onUpdate/onComplete.
• Line ~123: still the old checkoutDidFail(error:) spelling — here and at ~305, 319, 368, 411, 422. With the new default no-op, copying this compiles but never receives failures.

[github-actions]

Protocol — Coverage Report

Lines	Statements	Branches	Functions
	93.58% (146/156)	87.75% (86/98)	90% (27/30)

[github-actions]

Web — Coverage Report

Lines	Statements	Branches	Functions
	94.47% (342/362)	81.77% (166/203)	96.84% (92/95)

[github-actions]

React Native — Coverage Report

Lines	Statements	Branches	Functions
	90.97% (363/399)	87.29% (213/244)	100% (92/92)