diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index dd304f9..883cbea 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -32,8 +32,24 @@ jobs:
           - os: ubuntu-latest
             arch: x64
             version: '1.12'
+          - os: macos-latest
+            arch: arm64
+            version: '1.12'
+          # Windows is disabled while the silent test-suite stall is being
+          # debugged locally. The 90-minute job cap is hit consistently even
+          # after warm depot cache, D:-drive depot, coverage off and
+          # check_bounds=auto reduce setup + pre-test precompile to ~3
+          # minutes. The test runner then goes silent for 70+ minutes with
+          # no output before the cap, so the stall is inside the test suite
+          # itself. Re-enable once the hung @testset is identified and
+          # either fixed or skipped.
 
     steps:
+      - name: Cap precompile concurrency (macOS)
+        if: runner.os == 'macOS'
+        shell: bash
+        run: echo "JULIA_NUM_PRECOMPILE_TASKS=2" >> "$GITHUB_ENV"
+
       - name: Checkout OMBackend.jl
         uses: actions/checkout@v4
         with:
@@ -84,13 +100,26 @@ jobs:
         uses: julia-actions/julia-runtest@v1
         with:
           project: OMBackend.jl
+          # Coverage forces --pkgimages=no, which rejects the warm depot cache
+          # and forces a full precompile on every run. Keep coverage on Linux,
+          # where it is cheap, and disable it on Windows and macOS so the
+          # restored pkgimage cache is actually usable on those runners.
+          coverage: ${{ runner.os == 'Linux' }}
+          # Use Julia's default bounds-check behavior (honor @inbounds) instead
+          # of the action default --check-bounds=yes. The forced setting is a
+          # separate precompile configuration, so it triggers a full pkgimage
+          # rebuild of every dependency on test entry and discards the warm
+          # depot cache restored above.
+          check_bounds: auto
 
       - name: Process coverage
+        if: runner.os == 'Linux'
         uses: julia-actions/julia-processcoverage@v1
         with:
           directories: OMBackend.jl/src
 
       - name: Upload coverage to Codecov
+        if: runner.os == 'Linux'
         uses: codecov/codecov-action@v4
         with:
           files: lcov.info