[Mikelle]

Closes https://github.com/paritytech/platform-bugs/issues/123

A product built against a newer protocol can send a request version the host doesn't know. The host refuses it with an UnsupportedVersion protocol error, and the call fails as Unsupported, like an unknown method.

• The dispatcher checks the request's first byte, which is its version, before running the handler. The refusal is [0, 1, trait, method, newest_version] on (255, 255), and the host logs it once per method.
• The dispatcher decodes requests for the handlers, so the generated dispatcher no longer repeats the decode step for every method (about 900 lines less).
• The product SDK settles the call as Unsupported and logs the newest version the host accepts.

Existing messages don't change. Apps released before this still answer MalformedFrame.

[github-actions]

Bundle size report

Compared with main at cc8aa21.

	Raw	Gzip	Brotli
truapi-host	8.10 MiB (+31.8 KiB, +0.4%)	5.73 MiB (+8.9 KiB, +0.2%)	5.43 MiB (+5.5 KiB, +0.1%)
truapi-provider	4.03 MiB	1.27 MiB	960.2 KiB
truapi	6.72 MiB (+1.5 KiB)	951.5 KiB (+423 B)	777.8 KiB (+406 B, +0.1%)
trinity-stack	562.4 KiB	225.5 KiB	186.6 KiB
Total	19.41 MiB (+33.3 KiB, +0.2%)	8.15 MiB (+9.3 KiB, +0.1%)	7.31 MiB (+5.9 KiB, +0.1%)

WebAssembly modules

	Raw	Gzip	Brotli
truapi-host/wasm/web/truapi_server_bg.wasm	2.99 MiB (+31.8 KiB, +1.0%)	1.04 MiB (+8.9 KiB, +0.8%)	793.8 KiB (+5.5 KiB, +0.7%)
truapi-host/wasm/web/truapi_verifiable_bg.wasm	4.89 MiB	4.64 MiB	4.61 MiB
truapi-provider/truapi_provider_bg.wasm	3.99 MiB	1.26 MiB	952.5 KiB
trinity-stack/wasm/trinity_stack_bg.wasm	525.1 KiB	217.1 KiB	179.3 KiB

Changed files (4)

	Raw	Gzip	Brotli
truapi-host/wasm/web/truapi_server_bg.wasm	2.99 MiB (+31.8 KiB, +1.0%)	1.04 MiB (+8.9 KiB, +0.8%)	793.8 KiB (+5.5 KiB, +0.7%)
truapi/client.js	34.2 KiB (+1.1 KiB, +3.2%)	8.3 KiB (+279 B, +3.4%)	7.1 KiB (+244 B, +3.5%)
truapi/scale.js	5.7 KiB (+254 B, +4.5%)	2.2 KiB (+87 B, +4.0%)	1.9 KiB (+85 B, +4.5%)
truapi/playground/codegen/truapi-dts.js	338.3 KiB (+174 B, +0.1%)	57.7 KiB (+57 B, +0.1%)	46.2 KiB (+77 B, +0.2%)

_{Commit: e14e635}

[github-actions]

CI Status: 24 required jobs green, 21 passed and 3 skipped by path filter.

All job results

job	result
android-app	success
android-bindings	success
bundle-size	success
changes	success
changeset-guard	success
cli-package	success
codegen	success
e2e	skipped
explorer	success
headless-install	success
host-wasm	success
ios-app	success
ios-bindings	success
licenses	success
playground	success
provider-android-bindings	skipped
release-guard	success
rust	success
ts-client	success
ts-debugger	success
ts-host	success
ts-trinity-stack	success
wasm-provider	success
workflow-lint	skipped

Signing credentials: valid as of 2026-10-26

_{Commit e14e6350 · run log}