Handle undefined optional protocol fields

[tiagocandido]

What changes are you making?

Treat optional undefined protocol fields as absent, matching JSON semantics when browser postMessage uses structured clone. Previously a checkout containing order: undefined could lose its entire start/update event. Required undefined fields, nulls where disallowed by the schema, and malformed nested objects remain invalid; the decoder preserves legacy fulfillment normalization.

Include the failing field path in safe decode diagnostics, keep the published TypeScript declarations aligned, and cover the shared codec through Web and React Native consumers.

How to test

From the repository root, with dependencies installed:

pnpm --dir protocol test
pnpm --dir protocol lint
pnpm --dir platforms/web lint
pnpm --dir platforms/web test
pnpm --dir platforms/web build
pnpm --dir platforms/web verify
pnpm --dir platforms/web sample:build

The full stack passes 88 protocol tests, 440 Web tests, Web lint/typechecks, package verification and sample build. The React Native protocol suite also passes all 19 tests. The structured-clone regression asserts that optional keys disappear from the delivered snapshot while invalid present orders are rejected.

[github-actions]

Protocol — Coverage Report

Lines	Statements	Branches	Functions
	93.49% (158/169)	89.16% (107/120)	90.9% (30/33)

[github-actions]

Web — Coverage Report

Lines	Statements	Branches	Functions
	95.17% (375/394)	84.32% (199/236)	97.08% (100/103)

[github-actions]

React Native — Coverage Report

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

[github-actions]

Package Size

Platform	Artifact	Base	Head	Delta
Web	npm tarball	90.0 KiB	90.9 KiB	+902 B
React Native	npm tarball	119.0 KiB	119.6 KiB	+584 B

Web file breakdown

File	Base	Head	Delta
dist/index.js.map	247.2 KiB	249.3 KiB	+2.2 KiB
dist/custom-elements.json	48.0 KiB	48.0 KiB	0 B
dist/index.d.ts	47.7 KiB	47.7 KiB	0 B
dist/index.js	41.2 KiB	41.8 KiB	+559 B
README.md	20.1 KiB	20.1 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	108.7 KiB	108.7 KiB	0 B
node_modules/@shopify/checkout-kit-protocol/src/generated/Models.d.ts	73.1 KiB	73.1 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/ProtocolRenameMap.ts	7.8 KiB	7.8 KiB	0 B
node_modules/@shopify/checkout-kit-protocol/src/generated/ProtocolNotifications.d.ts	7.6 KiB	7.6 KiB	0 B
…and 117 smaller files

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

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