ci: add GitHub Actions workflow (#1)

* ci: add github actions workflow

* ci: update moon registry before checks

* fix(tty): remove raw fd isatty surface

* ci: handle cross-platform test output

* ci: use msvc for windows native tests

* test(tty): skip pty probes on windows

* ci: force windows execution policy update

Author: tonyfettes

.github/workflows/ci.yml

@@ -0,0 +1,75 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - ubuntu-latest
+          - macos-latest
+          - windows-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup MSVC
+        if: runner.os == 'Windows'
+        uses: ilammy/msvc-dev-cmd@v1
+
+      - name: Configure Windows C compiler
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: '"MOON_CC=cl.exe" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append'
+
+      - name: Install MoonBit
+        if: runner.os != 'Windows'
+        shell: bash
+        run: |
+          curl -fsSL https://cli.moonbitlang.com/install/unix.sh | bash
+          echo "$HOME/.moon/bin" >> "$GITHUB_PATH"
+          echo "MOON_HOME=$HOME/.moon" >> "$GITHUB_ENV"
+
+      - name: Install MoonBit
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          Set-ExecutionPolicy RemoteSigned -Scope CurrentUser -Force
+          irm https://cli.moonbitlang.com/install/powershell.ps1 | iex
+          "$env:USERPROFILE\.moon\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+          "MOON_HOME=$env:USERPROFILE\.moon" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+
+      - name: Show MoonBit version
+        run: moon version --all
+
+      - name: Update package registry
+        run: moon update
+
+      - name: Check formatting
+        run: moon fmt --check
+
+      - name: Check packages
+        run: moon check
+
+      - name: Run tests
+        run: moon test
+
+      - name: Generate interfaces
+        if: runner.os != 'Windows'
+        run: moon info
+
+      - name: Verify generated files are current
+        if: runner.os != 'Windows'
+        run: git diff --exit-code

docs/plans/2026-05-21-isatty-os-error.md

@@ -19,15 +19,15 @@ Use `moonbitlang/async/os_error` for `isatty` failures instead of a local
 - `isatty` changes from raising `TtyError` to raising `@os_error.OSError`.
 - The local `TtyError` type is removed from the root interface.
 - Add the public `Fd` trait used by generic `isatty`.
-- Add `Fd` impls for `@async/types.Fd`, `@async/fs.File`,
+- Add `Fd` impls for concrete async I/O handles: `@async/fs.File`,
   `@async/pipe.PipeRead`, `@async/pipe.PipeWrite`, `@async/stdio.Input`, and
-  `@async/stdio.Output`.
+  `@async/stdio.Output`. Raw `@async/types.Fd` is intentionally not a
+  supported public input.
 
 ## Acceptance
 
 - `isatty` returns `true` for terminal handles.
 - `isatty` returns `false` for valid non-terminal handles.
-- Invalid fds raise `@os_error.OSError`.
 - `.mbti` contains only the intended `isatty` and `Fd` surface changes.
 
 ## Validation
@@ -46,12 +46,10 @@ Use `moonbitlang/async/os_error` for `isatty` failures instead of a local
 - Removed the root `TtyError` error type.
 - Kept non-terminal handles as `false` and invalid fd failures as OS errors.
 - Kept the fd-like generic shape by adding a public `Fd` trait and impls for
-  the async fd-bearing handle types already supported by root reader/writer
+  the concrete async I/O handle types already supported by root reader/writer
   traits.
 - Made `Reader` and `Writer` inherit `Fd` so fd-bearing constraints have one
   source of truth.
-- Updated the invalid fd white-box test to assert the `isatty` OS error
-  context.
 - Updated tests and the `examples/isatty` demo to pass stdio handles directly.
 
 ## Public API Audit
@@ -60,8 +58,9 @@ Use `moonbitlang/async/os_error` for `isatty` failures instead of a local
   `Bool raise @os_error.OSError`.
 - Root `.mbti` removes `TtyError`.
 - Root `.mbti` adds only the intended `Fd` trait and impls for
-  `@async/types.Fd`, `@async/fs.File`, `@async/pipe.PipeRead`,
-  `@async/pipe.PipeWrite`, `@async/stdio.Input`, and `@async/stdio.Output`.
+  `@async/fs.File`, `@async/pipe.PipeRead`, `@async/pipe.PipeWrite`,
+  `@async/stdio.Input`, and `@async/stdio.Output`; it does not expose raw
+  `@async/types.Fd` as an accepted `isatty` input.
 - Root `.mbti` changes `Reader` and `Writer` to inherit `Fd` instead of
   repeating their own `fd` method.
 - No parser state, terminal handle storage, platform resize behavior, or VT
@@ -76,3 +75,11 @@ Use `moonbitlang/async/os_error` for `isatty` failures instead of a local
 - `moon info`
 - generated `.mbti` diff reviewed
 - `git diff --check`
+
+## Follow-up CI Adjustment
+
+- Removed the raw `@async/types.Fd` impl from the public `Fd` surface. Unix
+  aliases that type to `Int`, but Windows keeps it opaque, so accepting the raw
+  type leaks platform handle details into `isatty`.
+- Removed the `isatty(-1)` white-box test because invalid integer fd behavior is
+  Unix-specific and not part of the cross-platform public contract.

isatty.mbt

@@ -20,11 +20,6 @@ pub(open) trait Fd {
   fn fd(Self) -> @async/types.Fd
 }
 
-///|
-pub impl Fd for @async/types.Fd with fn fd(self) {
-  self
-}
-
 ///|
 pub impl Fd for @async/fs.File with fn fd(self) {
   @async/fs.File::fd(self)

pkg.generated.mbti

@@ -85,7 +85,6 @@ pub struct WindowSize {
 pub(open) trait Fd {
   fn fd(Self) -> Int
 }
-pub impl Fd for Int
 pub impl Fd for @fs.File
 pub impl Fd for @pipe.PipeRead
 pub impl Fd for @pipe.PipeWrite

tests/isatty_test.mbt

@@ -38,21 +38,35 @@ async fn read_until_nul(pty : @pty.Pty, timeout_ms? : Int = 3000) -> String {
   @utf8.decode(buf.to_bytes())
 }
 
+///|
+fn parse_build_output(output : &@io.Data) -> String raise {
+  let output_text = output.text()
+  for line in output_text.split("\n") {
+    let line = line.trim()
+    if line.has_prefix("{") {
+      let data : &@io.Data = line
+      let build_output = data.json()
+      guard build_output is { "artifacts_path": [String(artifacts_path)], .. } else {
+        fail("invalid build output: \{output_text}")
+      }
+      return artifacts_path
+    }
+  }
+  fail("missing build output JSON: \{output_text}")
+}
+
 ///|
 async fn build(name : String) -> String {
   let (build_exit, build_stdout, build_stderr) = @process.collect_output(
     "moon",
     ["-C", "tests/\{name}", "run", ".", "--build-only"],
   )
   guard build_exit is 0 else { fail("build failed: \{build_stderr.text()}") }
-  let build_output = build_stdout.json()
-  guard build_output is { "artifacts_path": [String(artifacts_path)], .. } else {
-    fail("invalid build output: \{build_stdout.text()}")
-  }
-  artifacts_path
+  parse_build_output(build_stdout)
 }
 
 ///|
+#cfg(not(platform="windows"))
 async test "isatty" {
   @async.with_task_group() <| group => {
     let artifacts_path = build("isatty")

tests/moon.pkg

@@ -1,5 +1,6 @@
 import {
   "moonbitlang/async",
+  "moonbitlang/async/io",
   "moonbitlang/async/process",
   "moonbit-community/pty",
   "moonbitlang/core/encoding/utf8",

tty_wbtest.mbt

@@ -144,15 +144,6 @@ async test "tty window size rejects non tty output" {
   )
 }
 
-///|
-test "isatty rejects invalid fd" {
-  try isatty(-1) catch {
-    @os_error.OSError(_, context~) => @debug.assert_eq(context, "isatty")
-  } noraise {
-    _ => fail("expected invalid fd error")
-  }
-}
-
 ///|
 test "state buffer can be made raw" {
   assert_true(sizeof_state > 0)