[build] wasm support

.github/workflows/build-main.yml

@@ -4,7 +4,7 @@ on:
     branches:
       - main
 
-# One job per arch. They run in parallel; each internally serializes JVM → JS → Native
+# One job per arch. They run in parallel; each internally serializes JVM, JS, Native, Wasm
 # via build.yml's `max-parallel: 1` matrix. Add or comment out arches here when budget
 # allows; the runner-image mapping is duplicated below to keep the workflow
 # self-contained.

.github/workflows/build-pr.yml

@@ -9,7 +9,7 @@ concurrency:
   cancel-in-progress: true
 
 # One job per arch. They run in parallel (no `needs:` between them) but each one
-# internally serializes JVM → JS → Native via build.yml's `max-parallel: 1` matrix.
+# internally serializes JVM, JS, Native, Wasm via build.yml's `max-parallel: 1` matrix.
 # Add or comment out arches here when budget allows; the runner-image mapping for each
 # is duplicated below to keep the workflow self-contained.
 

.github/workflows/build.yml

@@ -1,8 +1,8 @@
 name: build
 # Reusable workflow: builds + tests one arch with the target axis serialized.
 #
-# Sequential within arch: `max-parallel: 1` on the `target` matrix means JVM → JS →
-# Native run one at a time inside this workflow invocation. Two same-arch jobs never
+# Sequential within arch: `max-parallel: 1` on the `target` matrix means JVM, JS,
+# Native, Wasm run one at a time inside this workflow invocation. Two same-arch jobs never
 # compete for the same runner pool, which previously caused container-stop timeouts
 # and resource starvation on arm64 under contention.
 #
@@ -37,7 +37,7 @@ jobs:
       fail-fast: false
       max-parallel: 1
       matrix:
-        target: [JVM, JS, Native]
+        target: [JVM, JS, Native, Wasm]
     runs-on: ${{ inputs.runner-image }}
     env:
       JAVA_OPTS: >-
@@ -54,10 +54,13 @@ jobs:
         with:
           fetch-depth: 0
 
+      # The WASM target requires Node 24+: it defaults to V8's Turboshaft Wasm pipeline (Node 22/23
+      # miscompile the generated WasmGC code and no longer accept --turboshaft-wasm). JS runs on the
+      # same version to keep a single Node across the matrix.
       - uses: actions/setup-node@v6.4.0
-        if: matrix.target == 'JS'
+        if: matrix.target == 'JS' || matrix.target == 'Wasm'
         with:
-          node-version: '22'
+          node-version: '24'
 
       - uses: actions/cache@v5
         env:

CONTRIBUTING.md

@@ -65,7 +65,7 @@ Before you begin, make sure you have the following installed:
 
 - **Java 21 (or later)**
 - **Scala**
-- **Node**
+- **Node** (Node 24+ to run the experimental WASM target: it defaults to V8's Turboshaft Wasm pipeline)
 - **sbt** (Scala Build Tool)
 - **Git**