Add WASM support: --wasm flag with Node.js and Deno runtimes by lostflydev · Pull Request #1 · lostflydev/scala-cli

lostflydev · 2026-03-06T09:50:14Z

Implements scala-cli issue VirtusLab#3316: integrate WebAssembly with Scala CLI.

What's added

--wasm CLI flag and //> using wasm directive to enable WASM output
--wasm-runtime <runtime> option and //> using wasmRuntime directive Supported values: node (default), deno, wasmtime, wasmedge, wasmer
--deno-version, --wasmtime-version, --wasmer-version options and corresponding directives for pinning runtime versions

Runtime support

Node.js (default): runs Scala.js WASM output with --experimental-wasm-exnref flag, requires Node.js >= 22
Deno: runs Scala.js WASM output; if not found on PATH, downloads automatically from GitHub releases via Coursier cache
Wasmtime / WasmEdge / Wasmer: return UnsupportedWasmRuntimeError pending upstream Scala.js standalone WASM support (Make Scala.js Wasm backend suitable for standalone Wasm VMs (a.k.a. support "server-side Wasm") scala-js/scala-js#4991)

…VirtusLab#4173) Bumps the npm-dependencies group in /website with 1 update: [@algolia/client-search](https://github.com/algolia/algoliasearch-client-javascript). Updates `@algolia/client-search` from 5.49.1 to 5.49.2 - [Release notes](https://github.com/algolia/algoliasearch-client-javascript/releases) - [Changelog](https://github.com/algolia/algoliasearch-client-javascript/blob/main/CHANGELOG.md) - [Commits](algolia/algoliasearch-client-javascript@5.49.1...5.49.2) --- updated-dependencies: - dependency-name: "@algolia/client-search" dependency-version: 5.49.2 dependency-type: direct:production update-type: version-update:semver-patch dependency-group: npm-dependencies ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Bumps the github-actions group with 4 updates: [docker/login-action](https://github.com/docker/login-action), [docker/metadata-action](https://github.com/docker/metadata-action), [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action) and [docker/build-push-action](https://github.com/docker/build-push-action). Updates `docker/login-action` from 3 to 4 - [Release notes](https://github.com/docker/login-action/releases) - [Commits](docker/login-action@v3...v4) Updates `docker/metadata-action` from 5 to 6 - [Release notes](https://github.com/docker/metadata-action/releases) - [Commits](docker/metadata-action@v5...v6) Updates `docker/setup-buildx-action` from 3 to 4 - [Release notes](https://github.com/docker/setup-buildx-action/releases) - [Commits](docker/setup-buildx-action@v3...v4) Updates `docker/build-push-action` from 6 to 7 - [Release notes](https://github.com/docker/build-push-action/releases) - [Commits](docker/build-push-action@v6...v7) --- updated-dependencies: - dependency-name: docker/login-action dependency-version: '4' dependency-type: direct:production update-type: version-update:semver-major dependency-group: github-actions - dependency-name: docker/metadata-action dependency-version: '6' dependency-type: direct:production update-type: version-update:semver-major dependency-group: github-actions - dependency-name: docker/setup-buildx-action dependency-version: '4' dependency-type: direct:production update-type: version-update:semver-major dependency-group: github-actions - dependency-name: docker/build-push-action dependency-version: '7' dependency-type: direct:production update-type: version-update:semver-major dependency-group: github-actions ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

…ributions

Add LLM policy & a PR template

Bumps [undici](https://github.com/nodejs/undici) from 7.18.2 to 7.24.1. - [Release notes](https://github.com/nodejs/undici/releases) - [Commits](nodejs/undici@v7.18.2...v7.24.1) --- updated-dependencies: - dependency-name: undici dependency-version: 7.24.1 dependency-type: indirect ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

…b#4180)

Bumps the github-actions group with 1 update: [webfactory/ssh-agent](https://github.com/webfactory/ssh-agent). Updates `webfactory/ssh-agent` from 0.9.1 to 0.10.0 - [Release notes](https://github.com/webfactory/ssh-agent/releases) - [Changelog](https://github.com/webfactory/ssh-agent/blob/master/CHANGELOG.md) - [Commits](webfactory/ssh-agent@a6f90b1...e838748) --- updated-dependencies: - dependency-name: webfactory/ssh-agent dependency-version: 0.10.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: github-actions ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

…ile by lines to improve framework discovery (VirtusLab#4185)

Bumps the npm-dependencies group in /website with 1 update: [sass](https://github.com/sass/dart-sass). Updates `sass` from 1.97.3 to 1.98.0 - [Release notes](https://github.com/sass/dart-sass/releases) - [Changelog](https://github.com/sass/dart-sass/blob/main/CHANGELOG.md) - [Commits](sass/dart-sass@1.97.3...1.98.0) --- updated-dependencies: - dependency-name: sass dependency-version: 1.98.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: npm-dependencies ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

…with disabled build server (VirtusLab#4181)

…tusLab#4178)

Co-authored-by: gh-actions <actions@github.com>

Support `-opt-inline:help`

…tests` (VirtusLab#4216)

…and config keys

…r removal

…omization through indirect overrides instead

Add proper deprecation logic for features & deprecate Ammonite for removal

Fix misc compiler warnings

Make each packaged native image use its own subdirectory under `nativeImageWorkDir` when cross-packaging

…#4226) Bumps the npm-dependencies group in /website with 6 updates: | Package | From | To | | --- | --- | --- | | [@docusaurus/core](https://github.com/facebook/docusaurus/tree/HEAD/packages/docusaurus) | `3.9.2` | `3.10.0` | | [@docusaurus/plugin-content-docs](https://github.com/facebook/docusaurus/tree/HEAD/packages/docusaurus-plugin-content-docs) | `3.9.2` | `3.10.0` | | [@docusaurus/preset-classic](https://github.com/facebook/docusaurus/tree/HEAD/packages/docusaurus-preset-classic) | `3.9.2` | `3.10.0` | | [@docusaurus/theme-common](https://github.com/facebook/docusaurus/tree/HEAD/packages/docusaurus-theme-common) | `3.9.2` | `3.10.0` | | [react](https://github.com/facebook/react/tree/HEAD/packages/react) | `19.2.4` | `19.2.5` | | [react-dom](https://github.com/facebook/react/tree/HEAD/packages/react-dom) | `19.2.4` | `19.2.5` | Updates `@docusaurus/core` from 3.9.2 to 3.10.0 - [Release notes](https://github.com/facebook/docusaurus/releases) - [Changelog](https://github.com/facebook/docusaurus/blob/main/CHANGELOG.md) - [Commits](https://github.com/facebook/docusaurus/commits/v3.10.0/packages/docusaurus) Updates `@docusaurus/plugin-content-docs` from 3.9.2 to 3.10.0 - [Release notes](https://github.com/facebook/docusaurus/releases) - [Changelog](https://github.com/facebook/docusaurus/blob/main/CHANGELOG.md) - [Commits](https://github.com/facebook/docusaurus/commits/v3.10.0/packages/docusaurus-plugin-content-docs) Updates `@docusaurus/preset-classic` from 3.9.2 to 3.10.0 - [Release notes](https://github.com/facebook/docusaurus/releases) - [Changelog](https://github.com/facebook/docusaurus/blob/main/CHANGELOG.md) - [Commits](https://github.com/facebook/docusaurus/commits/v3.10.0/packages/docusaurus-preset-classic) Updates `@docusaurus/theme-common` from 3.9.2 to 3.10.0 - [Release notes](https://github.com/facebook/docusaurus/releases) - [Changelog](https://github.com/facebook/docusaurus/blob/main/CHANGELOG.md) - [Commits](https://github.com/facebook/docusaurus/commits/v3.10.0/packages/docusaurus-theme-common) Updates `react` from 19.2.4 to 19.2.5 - [Release notes](https://github.com/facebook/react/releases) - [Changelog](https://github.com/facebook/react/blob/main/CHANGELOG.md) - [Commits](https://github.com/facebook/react/commits/v19.2.5/packages/react) Updates `react-dom` from 19.2.4 to 19.2.5 - [Release notes](https://github.com/facebook/react/releases) - [Changelog](https://github.com/facebook/react/blob/main/CHANGELOG.md) - [Commits](https://github.com/facebook/react/commits/v19.2.5/packages/react-dom) --- updated-dependencies: - dependency-name: "@docusaurus/core" dependency-version: 3.10.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: npm-dependencies - dependency-name: "@docusaurus/plugin-content-docs" dependency-version: 3.10.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: npm-dependencies - dependency-name: "@docusaurus/preset-classic" dependency-version: 3.10.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: npm-dependencies - dependency-name: "@docusaurus/theme-common" dependency-version: 3.10.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: npm-dependencies - dependency-name: react dependency-version: 19.2.5 dependency-type: direct:production update-type: version-update:semver-patch dependency-group: npm-dependencies - dependency-name: react-dom dependency-version: 19.2.5 dependency-type: direct:production update-type: version-update:semver-patch dependency-group: npm-dependencies ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

) Bumps [follow-redirects](https://github.com/follow-redirects/follow-redirects) from 1.15.11 to 1.16.0. - [Release notes](https://github.com/follow-redirects/follow-redirects/releases) - [Commits](follow-redirects/follow-redirects@v1.15.11...v1.16.0) --- updated-dependencies: - dependency-name: follow-redirects dependency-version: 1.16.0 dependency-type: indirect ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Add additional packaging.graalvm* directives * Add tests for invalid packaging.graalvmJavaVersion

Co-authored-by: gh-actions <actions@github.com>

…rser` module (VirtusLab#4192) * Migrate from old `using_directives` to Scala-rewritten `directives-parser` module * Refactor tests * Handle edge cases * Include `directives-parser` module in `AGENTS.md`

…lt` (VirtusLab#4235)

Implements scala-cli issue VirtusLab#3316: integrate WebAssembly with Scala CLI. - `--wasm` CLI flag and `//> using wasm` directive to enable WASM output - `--wasm-runtime <runtime>` option and `//> using wasmRuntime` directive Supported values: node (default), deno - `--deno-version`, `--wasmtime-version`, `--wasmer-version` options and corresponding directives for pinning runtime versions - **Node.js** (default): runs Scala.js WASM output with `--experimental-wasm-exnref` flag, requires Node.js >= 22 - **Deno**: runs Scala.js WASM output

…imes - Move --wasm flag to dedicated Wasm help group with --help-wasm option - Simplify wasmOptions parsing with fold/toRight pattern - Add runtime validation with UnrecognizedWasmRuntimeError in directives - Auto-enable WASM when wasmRuntime directive is set - Update reference documentation Code style: simplify denoNeedsWasmFlag, explicit runtime match cases, clean type annotation, scalfmt

…smRuntime bun) - Add BunNotFoundError with install hint - Add integration test for Bun (conditional on bun being on PATH) - Add actions/setup-node@v6 node-version:24 to all Linux integration test jobs: the default Node.js on ubuntu-24.04 runners is too old for Scala.js WASM GC (which requires Node.js >= 22). Matches docs-tests job which already pins node-version: 24

lostflydev force-pushed the scala-wasm-support branch 5 times, most recently from c6453eb to ddfadbc Compare March 9, 2026 05:51

Gedochao and others added 3 commits March 9, 2026 13:33

Bump Mill to 1.1.3 (was 1.1.2) (VirtusLab#4169)

90aa8d7

lostflydev force-pushed the scala-wasm-support branch from ddfadbc to cf1e65a Compare March 10, 2026 15:04

Gedochao and others added 16 commits March 12, 2026 11:42

Update Scala 3 Next RC to 3.8.3-RC2 (VirtusLab#4175)

4763be0

Refer the Scala 3 compiler policy on usage of LLM-based tools in cont…

1631f8c

…ributions

Add a PR template

03ec06a

Support --cross with the package sub-command (VirtusLab#4171)

48fa471

Allow to --watch extra paths with --watching (VirtusLab#4174)

6c20fe0

Merge pull request VirtusLab#4177 from Gedochao/dx/contributions

2c22e11

Add LLM policy & a PR template

Use targeted Java/Scala mappings with the doc sub-command (VirtusLa…

bdaa4f4

…b#4180)

Correct Native test bridge error message and parse META-INF service f…

c1d45d7

…ile by lines to improve framework discovery (VirtusLab#4185)

Bump coursier to 2.1.25-M24 (VirtusLab#4184)

ab8f4b9

Add support for --cross in the doc sub-command (VirtusLab#4183)

4c529d6

Warn when .java & .scala sources are used in a mixed compilation …

7df6c78

…with disabled build server (VirtusLab#4181)

Add AGENTS.md & agentskills for directives & integration tests (Vir…

2352850

…tusLab#4178)

Add support for local .m2 in publish local (VirtusLab#4179)

5ed4f79

lostflydev force-pushed the scala-wasm-support branch from 80fe137 to 40df564 Compare March 18, 2026 11:05

Add release notes for Scala CLI v1.12.5 (VirtusLab#4190)

1491ac3

lostflydev force-pushed the scala-wasm-support branch from 40df564 to f138e4c Compare March 22, 2026 08:30

github-actions Bot and others added 2 commits March 22, 2026 16:38

Update scala-cli.sh launcher for 1.12.5 (VirtusLab#4191)

57cff2e

Co-authored-by: gh-actions <actions@github.com>

Bump Scala 3 Next RC to 3.8.3-RC3 (VirtusLab#4194)

0b036e5

Gedochao and others added 29 commits April 8, 2026 23:33

Merge pull request VirtusLab#4215 from Gedochao/fix/opt-inline-help

e745fb5

Support `-opt-inline:help`

Run tests with JDK 26 (VirtusLab#4214)

ced20dd

Split release_notes.md into a separate test per-release-tag in `docs-…

fbc634d

…tests` (VirtusLab#4216)

Bump Ammonite to 3.0.9 (was 3.0.8)

b11b3a8

Add deprecation mechanism for CLI options, directives, sub-commands, …

f563923

…and config keys

Deprecate --ammonite, --ammonite-version, and --ammonite-arg fo…

f98a01f

…r removal

Add an agent skill for deprecating features

5f46837

NIT Fix misc compiler warnings

7136dbd

Avoid overriding CaseApp's constructor parameter by routing help cust…

6a6b282

…omization through indirect overrides instead

Fix duplicate setting of -deprecation in the build

8171090

Remove unchecked cast in GraalVM substitution

c50a124

Remove legacy GraalVM substitution workaround for pprint

b676d50

Merge pull request VirtusLab#4218 from Gedochao/update/ammonite-3.0.9

ce16108

Add proper deprecation logic for features & deprecate Ammonite for removal

Merge pull request VirtusLab#4220 from Gedochao/fix/compiler-warnings

9a1a4c5

Fix misc compiler warnings

Merge pull request VirtusLab#4221 from Gedochao/fix/flaky-cross-package

9541df4

Make each packaged native image use its own subdirectory under `nativeImageWorkDir` when cross-packaging

Add 'packaging.graalvmJvmId' directive (VirtusLab#4223)

700ee86

Bump announced Scala 3 Next RC version to 3.8.4-RC1 (VirtusLab#4219)

51b8a82

Bump scalafmt to 3.11.0 (was 3.10.7) (VirtusLab#4228)

0d17e33

Bump Scala.js to 1.21.0 (VirtusLab#4229)

8ed45ff

Add additional packaging.graalvm* directives (VirtusLab#4225)

8d20222

* Add additional packaging.graalvm* directives * Add tests for invalid packaging.graalvmJavaVersion

Add release notes for Scala CLI v1.13.0 (VirtusLab#4231)

ed37d80

Update scala-cli.sh launcher for 1.13.0 (VirtusLab#4232)

2de46c7

Co-authored-by: gh-actions <actions@github.com>

Migrate from old using_directives to Scala-rewritten `directives-pa…

2bee48c

…rser` module (VirtusLab#4192) * Migrate from old `using_directives` to Scala-rewritten `directives-parser` module * Refactor tests * Handle edge cases * Include `directives-parser` module in `AGENTS.md`

Fix docs & add tests for repositories.mirrors & `repositories.defau…

cd57741

…lt` (VirtusLab#4235)

lostflydev force-pushed the scala-wasm-support branch from 0794656 to 721bbcf Compare April 19, 2026 10:11

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Add WASM support: --wasm flag with Node.js and Deno runtimes#1

Add WASM support: --wasm flag with Node.js and Deno runtimes#1
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lostflydev commented Mar 6, 2026

What's added

Runtime support

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