[Swift/Kotlin] Change default link open behaviour to in-app browser by default

[markmur]

Delegated web links (window.open and similar) previously bounced buyers out to the platform's external browser, which breaks flow for things like terms/policy pages opened mid-checkout. This flips the default so HTTPS links open in an in-app surface — SFSafariViewController on iOS, Custom Tabs on Android — while mailto:, tel:, and custom schemes continue routing through UIApplication.open / Intent.ACTION_VIEW. Merchants who want the old behavior can still register a CheckoutProtocol.windowOpen handler.

Try the sample apps and tap a delegated link in checkout (e.g. a policy link); it should stay in-app. The settings screen lets you toggle the alternative "External app" handler to verify the override path.

[github-actions]

React Native — Coverage Report

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

[github-actions]

Package Size

Platform	Artifact	Base	Head	Delta
Android	release AAR	246.5 KiB	247.1 KiB	+627 B

Android file breakdown

File	Base	Head	Delta
classes.jar	260.7 KiB	261.3 KiB	+607 B
res/layout/checkout_view_content.xml	2.2 KiB	2.2 KiB	0 B
res/layout/checkout_sheet_content.xml	2.0 KiB	2.0 KiB	0 B
res/values/values.xml	1.2 KiB	1.2 KiB	0 B
R.txt	1.1 KiB	1.1 KiB	0 B
proguard.txt	798 B	798 B	0 B
AndroidManifest.xml	578 B	578 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
Swift	Install with Tophat
Kotlin	Install with Tophat

Checkout Kit E2E results

Status	Suite	Target	Platform	OS version tag	Device
✅	tests/shared/launch-smoke.yaml	kotlin	android	latest	Google Pixel 9 Android 17.0
✅	tests/shared/launch-smoke.yaml	swift	ios	latest	iPhone 15 iOS 27 Beta