Cover native protocol model serialization contracts

[markmur]

Exercise the generated Buyer, Context, PaymentCredential, SelectedPaymentInstrument, and Policy serializers with matching synthetic fixtures in Swift and Kotlin. Verify full and minimal payload round trips, nested extension preservation, known-field collision protection, and rejection of each missing required field.

With the preceding runtime tests, overall protocol line coverage increases from 22.56% to 28.42% in Swift and from 47.24% to 61.59% in Kotlin. Generated convenience APIs remain visible in the separate generated-code coverage row.

Stack

• Cover native protocol model serialization contracts #936
• Cover protocol runtime mapping and JSON contracts #935
• Report protocol runtime and generated coverage separately #934
• Enforce 85% line coverage for each Swift SDK target #929
• Raise Accelerated Checkouts coverage above 85% #928
• Enforce 85% Android SDK line coverage #927
• Aggregate cross-platform coverage in one PR comment #926
• Report Swift and Android test coverage #924
• Enforce 85% test coverage thresholds #923

[github-actions]

Bundle Size Budgets

Budget	Size	Limits	Result
Android AAR package (ZIP)	408.54 KiB (0 B)	450 KiB soft / 500 KiB hard	✅ Within budget

Bundle and package size

Web bundle sizes cover shipped runtime JavaScript. Package sizes cover the full published archive, including any source maps, declarations, and documentation it contains.

Platform	Measurement	Compression	Base	Head	Delta
Android	Library package (.aar)	ZIP	408.5 KiB	408.5 KiB	0 B

Android package files (uncompressed)

These are uncompressed file sizes; they do not sum to the compressed package size above.

File	Base	Head	Delta
classes.jar	435.2 KiB	435.2 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

How sizes are measured

Measured from the PR base SHA and PR head SHA. Web bundle rows sum shipped .js, .mjs, and .cjs files under dist/, excluding source maps and declarations. The gzip bundle size sums files compressed individually with gzip -n -9. npm package sizes are gzip-compressed .tgz archives; Android AAR sizes are ZIP archives. Package sizes are not final app binary sizes.