Add Windows to the CI matrix and cache the managed Bun download

.github/workflows/ci.yml

@@ -7,9 +7,14 @@ on:
 jobs:
   build:
     strategy:
+      fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
+    defaults:
+      run:
+        # One wrapper invocation everywhere: git-bash on the Windows runner runs ./mill too.
+        shell: bash
     steps:
       - uses: actions/checkout@v4
 
@@ -18,29 +23,44 @@ jobs:
           distribution: temurin
           java-version: '21'
 
+      - uses: actions/cache@v4
+        with:
+          path: ~/.cache/mill-bun
+          key: mill-bun-${{ runner.os }}-${{ hashFiles('millbun/src/mill/bun/BunToolchainModule.scala') }}
+
+      - name: Select Mill launcher
+        # The sh wrapper fetches Mill's native launcher, which has no Windows build
+        # ("This native mill launcher supports only Linux and macOS") — Windows goes
+        # through the committed mill.bat instead.
+        run: echo "MILL=./mill$([ "$RUNNER_OS" = "Windows" ] && echo .bat)" >> "$GITHUB_ENV"
+
       - uses: oven-sh/setup-bun@v2
         with:
           bun-version: 1.4.0
 
       - name: Compile
-        run: ./mill --no-server millbun.compile
+        run: $MILL --no-server millbun.compile
 
       - name: Unit Tests
-        run: ./mill --no-server millbun.test
+        run: $MILL --no-server millbun.test
 
       # The suite defaults to the managed toolchain; this job pins system Bun to the same
       # version so `findOnPath` resolution and version verification keep CI coverage, while
       # the managed-bun job covers the download/cache path.
       - name: Integration Tests
         env:
           MILL_BUN_USE_SYSTEM: 'true'
-        run: ./mill --no-server millbun.integration
+        run: $MILL --no-server millbun.integration
 
   managed-bun:
     strategy:
+      fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
+    defaults:
+      run:
+        shell: bash
     steps:
       - uses: actions/checkout@v4
 
@@ -49,7 +69,18 @@ jobs:
           distribution: temurin
           java-version: '21'
 
+      - uses: actions/cache@v4
+        with:
+          path: ~/.cache/mill-bun
+          key: mill-bun-${{ runner.os }}-${{ hashFiles('millbun/src/mill/bun/BunToolchainModule.scala') }}
+
+      - name: Select Mill launcher
+        # The sh wrapper fetches Mill's native launcher, which has no Windows build
+        # ("This native mill launcher supports only Linux and macOS") — Windows goes
+        # through the committed mill.bat instead.
+        run: echo "MILL=./mill$([ "$RUNNER_OS" = "Windows" ] && echo .bat)" >> "$GITHUB_ENV"
+
       - name: Managed Bun smoke test
         env:
           MILL_BUN_USE_SYSTEM: 'false'
-        run: ./mill --no-server millbun.integration.testOnly mill.bun.BunManagedToolchainIntegrationTests
+        run: $MILL --no-server millbun.integration.testOnly mill.bun.BunManagedToolchainIntegrationTests

CHANGELOG.md

@@ -22,20 +22,29 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `BunWorkspaceModule` for one install and lockfile across mixed Scala.js/TypeScript packages.
 - Published dependency manifest schema v2 with runtime, optional, and peer requirements.
 - `bunDoctor` diagnostics and managed-toolchain CI smoke coverage.
+- A committed lockfile written by a newer Bun fails frozen installs with regeneration guidance,
+  instead of surfacing bun's raw `UnknownLockfileVersion`.
 
 ### Changed
 
 - Scala.js linking delegates to Mill's standard linker hooks; applications now choose `scalaJSVersion` explicitly.
 - Development dependencies are local tooling inputs and are no longer published transitively.
 - `bunPackageJsonExtras` rejects dependency fields now represented by typed settings.
 - Missing dependency versions are represented as `latest` instead of an empty package.json value.
+- TypeScript `bunBundleFormat` is `Option[String]`, matching Scala.js; `None` lets `bun build` infer.
+- `unmanagedDeps` entries are staged into `vendor/` and declared as `file:./vendor/<name>`
+  dependencies, so local packages install under frozen lockfiles and locks stay portable.
+- The TypeScript install task is canonically `bunInstall`; Mill's inherited `npmInstall` delegates to it.
+- `bunToolEnv` is defined once on `BunToolchainModule` for all toolchain subprocesses, and the
+  TypeScript `bunRuntimeEnv` is public.
 
 ### Deprecated
 
 - Scala.js `bunBundle*` and `bunCompile*` task names in favor of their canonical aliases.
 - `bunOptionalDeps` in favor of `npmOptionalDeps`.
 - `managedBunExecutable` in favor of `bunExecutableOverride`.
 - The TypeScript `bunCompileExecutable: Boolean` switch in favor of the `compileExecutable` task.
+- The TypeScript test command `test` and the Scala.js test command `bunTest`, both in favor of `testForked`.
 
 ## [0.2.1] - Overridable test-time JS env (2026-04-17)
 

README.md

@@ -45,7 +45,7 @@ Scala.js versions are explicit: choose the version your application tests agains
 ./mill app.run
 ./mill app.bundle
 ./mill app.compileExecutable
-./mill app.test.test
+./mill app.test.testForked
 ```
 
 `BunScalaJSModule` delegates `fastLinkJS`, `fullLinkJS`, and test linking to Mill's standard `ScalaJSModule` hooks. That keeps the plugin compatible with Mill's linker lifecycle and removes its former private linker-worker coupling.
@@ -76,7 +76,7 @@ object app extends BunTypeScriptModule {
 ./mill app.run
 ./mill app.bundle
 ./mill app.compileExecutable
-./mill app.test.test
+./mill app.test.testForked
 ```
 
 ## Web applications

build.mill

@@ -41,8 +41,10 @@ object millbun extends ScalaModule, PublishModule {
         // pins rather than whatever the developer happens to have on PATH. The shared
         // download cache means all fixtures reuse one archive. Export MILL_BUN_USE_SYSTEM=true
         // to run against a local Bun instead.
-        "MILL_BUN_USE_SYSTEM" -> Task.env.getOrElse("MILL_BUN_USE_SYSTEM", "false"),
-        "MILL_BUN_REQUIRE_LOCKFILE" -> Task.env.getOrElse("MILL_BUN_REQUIRE_LOCKFILE", "false")
+        "MILL_BUN_USE_SYSTEM" -> Task.env.getOrElse("MILL_BUN_USE_SYSTEM", "false")
+        // The lockfile requirement runs the SHIPPED default (strict): dependency-bearing
+        // fixtures commit a bun.lock, regenerated via mill.bun.RegenerateFixtureLocks, and
+        // fixtures that deliberately test the relaxed path opt out in their own build.mill.
       )
     }
 

docs/MIGRATING-0.3.md

@@ -29,6 +29,25 @@ Subsequent installs are frozen. During a staged migration only, set `MILL_BUN_RE
 
 Use `npmDeps`, `npmDevDeps`, `npmOptionalDeps`, `npmPeerDeps`, and `npmOverrides`. `bunPackageJsonExtras` remains available for unmodeled fields such as `scripts`, but now rejects dependency sections so task invalidation and published metadata remain correct.
 
+### `bunBundleFormat` is `Option[String]` on TypeScript modules
+
+Scala.js and TypeScript previously disagreed on this member's type — `Option[String]` versus
+`String` — which no deprecation alias can bridge, so 0.3 takes the one-time break. Both are now
+`T[Option[String]]`; `None` lets `bun build` infer the format.
+
+```scala
+// 0.2
+override def bunBundleFormat = Task { "esm" }
+// 0.3
+override def bunBundleFormat = Task { Some("esm") }
+```
+
+### Local packages via `unmanagedDeps` must be directories with a `package.json`
+
+Entries are staged into `vendor/` beside the generated package.json and declared as
+`file:./vendor/<name>` dependencies, so they now work under frozen lockfile installs and the
+lockfile stays independent of the checkout path. Tarballs are no longer accepted — unpack them.
+
 ## Renamed APIs
 
 | 0.2 name | 0.3 name | Status |
@@ -39,9 +58,17 @@ Use `npmDeps`, `npmDevDeps`, `npmOptionalDeps`, `npmPeerDeps`, and `npmOverrides
 | `bunCompileExecutables` | `compileExecutables` | Compatibility alias retained |
 | `bunOptionalDeps` | `npmOptionalDeps` | Deprecated compatibility setting |
 | `managedBunExecutable` | `bunExecutableOverride` | Deprecated compatibility setting |
+| `npmInstall` (TypeScript) | `bunInstall` | Mill's inherited name delegates to `bunInstall` and stays usable |
+| `test` (TypeScript test modules) | `testForked` | Deprecated compatibility command |
+| `bunTest` (Scala.js test modules) | `testForked` (inherited from Mill) | Deprecated compatibility command |
 
 The old names are planned for removal at 1.0.
 
+Environment hooks share one vocabulary: `bunToolEnv` (toolchain subprocesses — install, lock,
+build) is defined on `BunToolchainModule` for every module kind, and the TypeScript
+`bunRuntimeEnv` (program and test processes) is now public. Scala.js keeps `bunJsEnv` /
+`bunJsEnvArgs` / `bunTestJsEnv` for its Scala.js-test JS environment, unchanged.
+
 ## Toolchain behavior
 
 The default is now checksum-verified managed Bun 1.4.0. To preserve the old PATH behavior:

examples/build.mill

@@ -79,7 +79,7 @@ object fullstack extends Module {
 // No moduleDir or sources overrides needed.
 //
 //   ./mill tsLib.compile                  # TypeScript type-check
-//   ./mill tsLib.test.test                # Bun-native tests
+//   ./mill tsLib.test.testForked              # Bun-native tests
 //   ./mill client.bundle                  # TS browser bundle (imports tsLib)
 //   ./mill scalaClient.bundle             # Scala.js browser bundle
 //   ./mill backend.run                    # JVM Cask server on :8080