Add macOS coverage to Go CI

.github/workflows/ci.yml

@@ -75,7 +75,8 @@ jobs:
     - name: Lint - auth-protocol boundary (#1212 anti-regression)
       run: bash scripts/lint-auth-signals.sh
 
-  # Linux-only for PR feedback. Full platform matrix (incl. macOS + Windows) runs post-merge in build-release.yml.
+  # Python test + binary build remain Linux-only for PR feedback. Full packaged
+  # platform coverage (incl. macOS + Windows) runs post-merge in build-release.yml.
   # Combines unit tests + binary build into a single job to eliminate runner re-provisioning overhead.
   build-and-test:
     name: Build & Test (Linux)
@@ -128,6 +129,31 @@ jobs:
         retention-days: 30
         if-no-files-found: error
 
+  go-build-test:
+    name: Go Build & Test (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    permissions:
+      contents: read
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-24.04, macos-latest]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up Go
+      uses: actions/setup-go@v5
+      with:
+        go-version-file: go.mod
+        cache: true
+
+    - name: Run Go tests
+      run: go test ./...
+
+    - name: Run Go build
+      run: go build ./...
+
   # Dogfood the two CI gates we ship and document to users:
   #   - Gate A (consumer-side): `apm audit --ci` -- lockfile / install fidelity.
   #   - Gate B (producer-side): regeneration drift -- did someone hand-edit

internal/utils/reflink/reflink_other.go

@@ -1,4 +1,4 @@
-//go:build !linux && !darwin
+//go:build !linux
 
 package reflink
 

tests/unit/test_ci_workflows.py

@@ -0,0 +1,24 @@
+from pathlib import Path
+
+import yaml
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+
+
+def _load_ci_workflow():
+    return yaml.safe_load((REPO_ROOT / ".github/workflows/ci.yml").read_text())
+
+
+def test_go_build_test_matrix_includes_macos():
+    job = _load_ci_workflow()["jobs"]["go-build-test"]
+
+    assert job["runs-on"] == "${{ matrix.os }}"
+    assert job["strategy"]["matrix"]["os"] == ["ubuntu-24.04", "macos-latest"]
+
+
+def test_go_build_test_runs_build_and_tests():
+    steps = _load_ci_workflow()["jobs"]["go-build-test"]["steps"]
+    commands = [step.get("run") for step in steps]
+
+    assert "go test ./..." in commands
+    assert "go build ./..." in commands