Bundle-split TS code

[markmur]

What changes are you making?

Shrinks the web bundle by removing the quicktype Convert/typeMap runtime from the decode path and letting the web build tree-shake it out.

Before: the generated typeMap both validates (recursively) and remaps snake_case ↔ camelCase. It's resolved by string key, so it can't be tree-shaken while any Convert.* method is referenced — it shipped in the web bundle in full (~25 KB).

After:

• A generated structural remap skeleton (SHAPES) + a small generated required-field table (REQUIRED), emitted by generate_case_map.mjs into generated/CaseMap.ts.
• A hand-written walker (case_transform.ts: camelizeKeys / snakeifyKeys) that renames keys mechanically and recurses typed dictionaries while preserving dynamic map keys verbatim.
• sideEffects: false on the protocol TS package so the web build can drop the now-unreferenced Convert runtime.

Measured impact (web bundle, vs base branch)

Artifact	Before	After	Δ
dist/index.js (raw)	48,698 B	29,374 B	−19,324 B (−39.7%)
dist/index.js (gzip)	9,684 B	7,749 B	−1,935 B (−20.0%)
dist/index.js.map	184,211 B	95,273 B	−88,938 B (−48.3%)

The quicktype runtime is confirmed absent from the built bundle (its Expected … but got … error string is gone). The Package Size check reports exact deltas on this PR.

Tests: protocol 43/43, web 116/116 (100% line coverage), React Native 18/18.

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Tradeoffs

1. Remapping moves from a validated typeMap to a generated skeleton + generic walker.

The walker is now the single decode path for every consumer of the TS protocol package (web and React Native). Correctness depends on the generated SHAPES skeleton staying in sync with the models — it is regenerated as part of the codegen pipeline (generate_models.sh → generate_case_map.mjs), so it can't drift by hand. One sharp edge this surfaced: dictionaries whose values are typed objects (e.g. ucp.payment_handlers, ucp.services) must carry their element type in SHAPES so the walker recurses into the values while leaving the dynamic keys untouched; free-form maps (e.g. constraints) are left verbatim.

2. Decode validation is now top-level only (not recursive).

camelizeKeys validates required top-level fields (presence, plus typeof for string-typed fields) and still returns JSON-RPC INVALID_PARAMS (-32602) when the top-level payload is missing or the wrong shape. It intentionally does not reproduce the old recursive quicktype validation, so it no longer catches:

• missing nested required fields,
• non-string type errors on top-level structural fields (line_items / links / totals / ucp / status are presence-only),
• enum value mismatches.

Why this is an acceptable trade: payloads on this boundary are first-party (the Shopify checkout iframe), the layer's actual job is snake ↔ camel remapping, and recursive validation is brittle against protocol version skew — a single unrecognized nested field could reject an entire checkout update and break the UI. Presence-checking the top level keeps the "reject obviously malformed params" contract without that fragility.

Restoring deeper validation later is byte-cheap: REQUIRED already enumerates every type, so it can be walked recursively without regenerating anything.

Follow-up (not in this PR)

The {checkout} / {error} params envelope narrowing still lives in the protocol descriptors. It's slated to move into each platform kit so the protocol package stays purely wire-level.

---

Before you merge

Important

• I've added tests to support my implementation
• I have read and agree with the Contribution Guidelines
• I have read and agree with the Code of Conduct
• I've updated the relevant platform README (platforms/swift/README.md and/or platforms/android/README.md)

---

Releasing a new Swift version?

• I have bumped the version in ShopifyCheckoutKit.podspec
• I have bumped the version in platforms/swift/Sources/ShopifyCheckoutKit/ShopifyCheckoutKit.swift
• I have updated the SwiftPM/CocoaPods version snippets in platforms/swift/README.md (major version only)

Releasing a new Embedded Checkout Protocol version?

• I have bumped embeddedCheckoutProtocolAndroid in platforms/android/gradle/libs.versions.toml
• I have updated protocol/languages/kotlin/embedded-checkout-protocol/api/embedded-checkout-protocol.api if the public API changed

Releasing a new Android version?

• I have bumped checkoutKitAndroid in platforms/android/gradle/libs.versions.toml
• I have updated the Gradle/Maven version snippets in platforms/android/README.md

Tip

See the Contributing documentation for the full release process per platform.

[github-actions]

Package Size

Platform	Artifact	Base	Head	Delta
Web	npm tarball	66.6 KiB	48.1 KiB	-18.5 KiB
React Native	npm tarball	99.4 KiB	96.4 KiB	-3.0 KiB
Android	release AAR	160.8 KiB	160.8 KiB	0 B

Web file breakdown

File	Base	Head	Delta
dist/index.js.map	179.9 KiB	75.9 KiB	-104.0 KiB
dist/index.js	47.6 KiB	22.2 KiB	-25.4 KiB
dist/custom-elements.json	38.0 KiB	38.0 KiB	0 B
src/checkout.ts	26.5 KiB	26.5 KiB	0 B
README.md	16.4 KiB	16.4 KiB	0 B
dist/checkout.d.ts	6.9 KiB	6.9 KiB	0 B
src/checkout.types.ts	4.1 KiB	4.1 KiB	0 B
dist/checkout.types.d.ts	3.0 KiB	3.0 KiB	0 B
package.json	2.9 KiB	2.9 KiB	0 B
src/checkout.styles.ts	2.8 KiB	2.8 KiB	0 B
src/utils.ts	1.7 KiB	1.7 KiB	0 B
dist/utils.d.ts	1.4 KiB	1.4 KiB	0 B
src/index.ts	1.2 KiB	1.2 KiB	0 B
LICENSE	1.1 KiB	1.1 KiB	0 B
dist/index.d.ts	738 B	738 B	0 B
src/checkout-web-component.ts	271 B	271 B	0 B
dist/checkout-web-component.d.ts	154 B	154 B	0 B
dist/checkout.styles.d.ts	79 B	79 B	0 B

React Native file breakdown

File	Base	Head	Delta
node_modules/@shopify/checkout-kit-protocol/src/generated/Models.ts	85.8 KiB	51.5 KiB	-34.4 KiB
node_modules/@shopify/checkout-kit-protocol/src/generated/Models.d.ts	53.2 KiB	51.7 KiB	-1.5 KiB
ios/ShopifyCheckoutKit.swift	15.0 KiB	15.0 KiB	0 B
ios/AcceleratedCheckoutButtons.swift	14.0 KiB	14.0 KiB	0 B
lib/commonjs/index.js	13.1 KiB	13.1 KiB	0 B
src/components/AcceleratedCheckoutButtons.tsx	12.9 KiB	12.9 KiB	0 B
src/index.ts	12.5 KiB	12.5 KiB	0 B
lib/commonjs/components/AcceleratedCheckoutButtons.js	11.4 KiB	11.4 KiB	0 B
android/src/main/java/com/shopify/reactnative/checkoutkit/ShopifyCheckoutKitModule.java	11.1 KiB	11.1 KiB	0 B
lib/module/index.js	10.4 KiB	10.4 KiB	0 B
lib/commonjs/components/AcceleratedCheckoutButtons.js.map	10.3 KiB	10.3 KiB	0 B
lib/module/components/AcceleratedCheckoutButtons.js	10.2 KiB	10.2 KiB	0 B
lib/module/components/AcceleratedCheckoutButtons.js.map	9.1 KiB	9.1 KiB	0 B
src/index.d.ts	8.9 KiB	8.9 KiB	0 B
node_modules/@shopify/checkout-kit-protocol/src/generated/ProtocolNotifications.ts	8.5 KiB	8.5 KiB	+31 B
lib/module/index.js.map	8.2 KiB	8.2 KiB	0 B
src/present-dispatcher.ts	8.0 KiB	8.0 KiB	0 B
lib/commonjs/index.js.map	7.7 KiB	7.7 KiB	0 B
lib/commonjs/present-dispatcher.js	6.8 KiB	6.8 KiB	0 B
lib/module/present-dispatcher.js	6.5 KiB	6.5 KiB	0 B
…and 109 smaller files

Android file breakdown

File	Base	Head	Delta
classes.jar	170.2 KiB	170.2 KiB	0 B
res/layout/dialog_checkout.xml	1.3 KiB	1.3 KiB	0 B
proguard.txt	798 B	798 B	0 B
AndroidManifest.xml	578 B	578 B	0 B
res/values/values.xml	564 B	564 B	0 B
R.txt	522 B	522 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.

[github-actions]

React Native — Coverage Report

Lines	Statements	Branches	Functions
	91.85% (327/356)	87.98% (183/208)	100% (86/86)