diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6e66697..174cb55 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -2,9 +2,9 @@ name: CI
 
 on:
   push:
-    branches: [main]
+    branches: [master]
   pull_request:
-    branches: [main]
+    branches: [master]
 
 permissions:
   contents: read
@@ -19,32 +19,79 @@ jobs:
       - run: uv run ruff check warp_cache/ tests/ benchmarks/
       - run: uv run ty check
 
-  test:
+  clippy:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13"]
     steps:
       - uses: actions/checkout@v4
-      - uses: astral-sh/setup-uv@v5
-        with:
-          python-version: ${{ matrix.python-version }}
-      - name: Build extension
-        uses: PyO3/maturin-action@v1
+      - uses: dtolnay/rust-toolchain@stable
         with:
-          args: --release --out dist -i python${{ matrix.python-version }}
-      - name: Install wheel and dev deps
-        run: |
-          uv venv --python ${{ matrix.python-version }}
-          uv pip install dist/*.whl
-          uv pip install pytest pytest-asyncio
-      - run: uv run pytest tests/ -v
+          components: clippy
+      - uses: Swatinem/rust-cache@v2
+      - run: cargo clippy -- -D warnings
 
-  clippy:
-    runs-on: ubuntu-latest
+  clippy-windows:
+    runs-on: windows-latest
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
         with:
           components: clippy
+      - uses: Swatinem/rust-cache@v2
       - run: cargo clippy -- -D warnings
+
+  test:
+    needs: [lint, clippy]
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          # Linux x86_64 — full Python coverage
+          - os: ubuntu-latest
+            python-version: "3.10"
+          - os: ubuntu-latest
+            python-version: "3.11"
+          - os: ubuntu-latest
+            python-version: "3.12"
+          - os: ubuntu-latest
+            python-version: "3.13"
+          # Linux arm64 — boundary versions
+          - os: ubuntu-24.04-arm
+            python-version: "3.10"
+          - os: ubuntu-24.04-arm
+            python-version: "3.13"
+          # macOS arm64 — boundary versions
+          - os: macos-latest
+            python-version: "3.10"
+          - os: macos-latest
+            python-version: "3.13"
+          # Windows x86_64 — boundary versions
+          - os: windows-latest
+            python-version: "3.10"
+          - os: windows-latest
+            python-version: "3.13"
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: Swatinem/rust-cache@v2
+        with:
+          key: ${{ matrix.os }}-py${{ matrix.python-version }}
+      - uses: astral-sh/setup-uv@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install build and test deps
+        run: uv pip install maturin pytest pytest-asyncio
+      - name: Build extension
+        run: uv run maturin develop --release
+      - name: Run tests
+        shell: bash
+        run: |
+          if [[ "${{ runner.os }}" == "Windows" ]]; then
+            uv run pytest tests/ -v \
+              --ignore=tests/test_shared_basic.py \
+              --ignore=tests/test_shared_multiprocess.py \
+              --ignore=tests/test_shared_realistic.py \
+              -k "not (TestSharedComplex or async_shared_backend)"
+          else
+            uv run pytest tests/ -v
+          fi
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..f7208b2
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,5 @@
+import sys
+
+collect_ignore_glob = []
+if sys.platform == "win32":
+    collect_ignore_glob = ["test_shared_*.py"]
diff --git a/tests/test_async.py b/tests/test_async.py
index bf62e1c..52cf780 100644
--- a/tests/test_async.py
+++ b/tests/test_async.py
@@ -1,4 +1,5 @@
 import asyncio
+import sys
 
 import pytest
 
@@ -143,6 +144,7 @@ async def fn(x):
 # ── Shared backend ───────────────────────────────────────────────────────
 
 
+@pytest.mark.skipif(sys.platform == "win32", reason="shared memory is Unix-only")
 @pytest.mark.asyncio
 async def test_async_shared_backend():
     call_count = 0
diff --git a/tests/test_complex_objects.py b/tests/test_complex_objects.py
index 088010b..7f70c86 100644
--- a/tests/test_complex_objects.py
+++ b/tests/test_complex_objects.py
@@ -3,11 +3,16 @@
 import contextlib
 import glob
 import os
+import sys
 import tempfile
 from dataclasses import dataclass
 
+import pytest
+
 from warp_cache import cache
 
+_skip_on_windows = pytest.mark.skipif(sys.platform == "win32", reason="shared memory is Unix-only")
+
 # ---------------------------------------------------------------------------
 # Helpers
 # ---------------------------------------------------------------------------
@@ -244,6 +249,7 @@ def f(a, b, c, d, e):
 # ===========================================================================
 
 
+@_skip_on_windows
 class TestSharedComplexValues:
     def setup_method(self):
         _cleanup_shm()
@@ -315,6 +321,7 @@ def mixed():
         assert mixed() == result
 
 
+@_skip_on_windows
 class TestSharedComplexKeys:
     def setup_method(self):
         _cleanup_shm()