[build] wasm support#1663
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### Problem Kyo cross-compiles to JVM, Scala.js, and Scala Native, but not WebAssembly. Scala.js now ships an experimental WebAssembly backend (WasmGC), so the toolchain exists; Kyo simply had no target wired for it. The goal is WASM as a first-class, tested cross-build target, so the full stack (up to and including kyo-http servers) runs on WasmGC runtimes. ### Solution Add a `WasmPlatform` to the sbt cross-build, mirroring the existing Scala.js setup (it enables the Scala.js plugin with the experimental WebAssembly linker and ESModule output). The WASM backend shares Scala.js's single-threaded, Node-hosted model, so JS and WASM share platform code through a `js-wasm` source directory. Most of the diff is mechanical: JS-only sources moving into that shared directory so both backends pick them up. Every module that targets Scala.js now also targets WASM, except the two cats-effect bridges (see Notes), with a matching CI matrix row and aggregator. The platform-specific code is small: a per-platform trampoline depth in `kyo.internal.Platform`, a few Node builtin facades for the http tier, and a `notWasm` tag for the two kernel tests that deliberately overflow the stack. The README gains a Platforms section and a WASM column across the module tables. ### Notes - Requires **Node 24+**. Node 24 makes V8's Turboshaft Wasm pipeline the default; Node 22/23 miscompile the generated WasmGC code under legacy TurboFan, and Node 24 removed the opt-in flag. CI, CONTRIBUTING, and the build pin and document this. - `kyo-cats` and `kyo-compat-ce` are intentionally not built for WASM: cats-effect does not support the backend yet, filed upstream as [cats-effect#4608](typelevel/cats-effect#4608). They re-enable once that lands. - This also lowers Scala Native's trampoline depth to match WASM (256, vs 512 on JVM/JS), since native frames are larger and the lower bound is the safe shared value. Flagging it because it changes existing Native behavior. - Validated the WASM suite on Node 24 module by module; kyo-http serves real HTTP and HTTPS over Node sockets under WASM. The Chrome/Docker-driven modules (kyo-browser, kyo-ui, kyo-pod) run through the CI matrix. - Folds in one pre-existing README fix: `kyo-reactive-streams` was marked JVM-only but already cross-compiles to JS and Native (corrected, plus WASM).
- build.sbt: keep both imports (WasmCrossProject.* + WithKyoTest._) - kyo-test: add wasm platform filters (.wasm/.notWasm/.onlyWasm) and a Both[A,B] composition marker so .notNative.notWasm gates on both; #1658 replaced the ScalaTest tagging #1663 relied on - KyoTest/ChoiceTest: express the wasm exclusion as .notNative.notWasm - delete the obsolete ScalaTest Tagged.scala helpers (deleted on main)
#1658 replaced ScalaTest with kyo-test but only cross-built it for JVM/JS/Native. #1663 runs tests on a 4th target (Wasm), so the kyo-test modules and the WithKyoTest wiring need a wasm variant. - build.sbt: add WasmPlatform + .wasmSettings to kyo-test-api/runner/prop/ snapshot (snapshot keeps WasmPlatform's ESModule for the @jsimport node:fs facade); aggregate them into kyoWasm - WithKyoTest: add a wasm branch wiring kyo-test-runnerWasm and reusing JsFramework (wasm is a Scala.js linker backend with the same sbt test bridge) - move the 15 kyo-test js sources into js-wasm/ (shared js+wasm), mirroring how kyo-core shares Scala.js code across js and wasm Validated: kyoWasm/Test/compile green across all modules; kyo-kernel + kyo-prelude + kyo-core run green on wasm (2000+ tests, 0 failed) with the .notNative.notWasm leaves correctly compile-excluded; JS unchanged.
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Fixes #217
Problem
Kyo cross-compiles to JVM, Scala.js, and Scala Native, but not WebAssembly. Scala.js now ships an experimental WebAssembly backend (WasmGC), so the toolchain exists; Kyo simply had no target wired for it. The goal is WASM as a first-class, tested cross-build target, so the full stack (up to and including kyo-http servers) runs on WasmGC runtimes.
Solution
Add a
WasmPlatformto the sbt cross-build, mirroring the existing Scala.js setup (it enables the Scala.js plugin with the experimental WebAssembly linker and ESModule output). The WASM backend shares Scala.js's single-threaded, Node-hosted model, so JS and WASM share platform code through ajs-wasmsource directory. Most of the diff is mechanical: JS-only sources moving into that shared directory so both backends pick them up.Every module that targets Scala.js now also targets WASM, except the two cats-effect bridges (see Notes), with a matching CI matrix row and aggregator. The platform-specific code is small: a per-platform trampoline depth in
kyo.internal.Platform, a few Node builtin facades for the http tier, and anotWasmtag for the two kernel tests that deliberately overflow the stack. The README gains a Platforms section and a WASM column across the module tables.Notes
kyo-catsandkyo-compat-ceare intentionally not built for WASM: cats-effect does not support the backend yet, filed upstream as cats-effect#4608. They re-enable once that lands.kyo-reactive-streamswas marked JVM-only but already cross-compiles to JS and Native (corrected, plus WASM).