diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 6cca7d4..d1a7c89 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -17,13 +17,13 @@ jobs:
   package:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           filter: blob:none
           fetch-depth: 0
           persist-credentials: false
       - name: Install uv
-        uses: astral-sh/setup-uv@11f9893b081a58869d3b5fccaea48c9e9e46f990 # v8.3.2
+        uses: astral-sh/setup-uv@1c37ad07a6a961277cf70c0d37d6f313000f5884 # v10.3.0
       - name: Build package
         run: uv build
       - name: Check package
diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index 159ba8c..027201b 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -18,16 +18,16 @@ jobs:
       contents: read
       id-token: write # IMPORTANT: this permission is mandatory for trusted publishing
     steps:
-      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           filter: blob:none
           fetch-depth: 0
           persist-credentials: false
       - name: Install uv
-        uses: astral-sh/setup-uv@11f9893b081a58869d3b5fccaea48c9e9e46f990 # v8.3.2
+        uses: astral-sh/setup-uv@1c37ad07a6a961277cf70c0d37d6f313000f5884 # v10.3.0
         with:
           enable-cache: false
       - name: Build package
         run: uv build
       - name: Publish package distributions to PyPI
-        uses: pypa/gh-action-pypi-publish@cef221092ed1bacb1cc03d23a2d87d1d172e277b # v1.14.0
+        uses: pypa/gh-action-pypi-publish@dc37677b2e1c63e2034f94d8a5b11f265b73ba33 # v1.14.2
diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index 0075425..3656e3b 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -26,13 +26,13 @@ jobs:
     outputs:
       envs: ${{ steps.get-envs.outputs.envs }}
     steps:
-      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           filter: blob:none
           fetch-depth: 0
           persist-credentials: false
       - name: Install uv
-        uses: astral-sh/setup-uv@11f9893b081a58869d3b5fccaea48c9e9e46f990 # v8.3.2
+        uses: astral-sh/setup-uv@1c37ad07a6a961277cf70c0d37d6f313000f5884 # v10.3.0
       - name: Get test environments
         id: get-envs
         run: |
@@ -65,13 +65,13 @@ jobs:
     continue-on-error: ${{ contains(matrix.env.name, 'pre') }}  # make "all-green" pass even if pre-release job fails
 
     steps:
-      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           filter: blob:none
           fetch-depth: 0
           persist-credentials: false
       - name: Install uv
-        uses: astral-sh/setup-uv@11f9893b081a58869d3b5fccaea48c9e9e46f990 # v8.3.2
+        uses: astral-sh/setup-uv@1c37ad07a6a961277cf70c0d37d6f313000f5884 # v10.3.0
         with:
           python-version: ${{ matrix.env.python }}
       - name: create hatch environment
@@ -91,7 +91,7 @@ jobs:
           uvx hatch run ${{ matrix.env.name }}:cov-report   # report visibly
           uvx hatch run ${{ matrix.env.name }}:coverage xml # create report for upload
       - name: Upload coverage
-        uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f # v7.0.0
+        uses: codecov/codecov-action@303a32d7a59b442fa8d48b6a1cc6825c09c847a5 # v7.1.1
         with:
           fail_ci_if_error: true
           use_oidc: true
@@ -106,6 +106,6 @@ jobs:
       - test
     runs-on: ubuntu-latest
     steps:
-        - uses: re-actors/alls-green@05ac9388f0aebcb5727afa17fcccfecd6f8ec5fe # v1.2.2
+        - uses: re-actors/alls-green@b5b5b37504aa4183270bd3d855c52a67f212be35 # v1.3.0
           with:
             jobs: ${{ toJSON(needs) }}
diff --git a/tests/conftest.py b/tests/conftest.py
index 24da045..588b5a0 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -57,11 +57,17 @@ def adata() -> ad.AnnData:
 
 
 @pytest.fixture(scope="session")
-def codex_adata() -> ad.AnnData:
-    """Load the two CODEX samples shared by the graph and shape tests."""
+def _codex_adata() -> ad.AnnData:
+    """Load the two CODEX samples once per test session."""
     return _load_codex(_CODEX_PATH)
 
 
+@pytest.fixture()
+def codex_adata(_codex_adata: ad.AnnData) -> ad.AnnData:
+    """Give each test its own copy of the CODEX samples."""
+    return _codex_adata.copy()
+
+
 def _load_codex(path: Path) -> ad.AnnData:
     """Download and read the shared fixture without races between pytest workers."""
     max_retries = 3