diff --git a/.github/workflows_disabled b/.github/workflows/ci.yml
similarity index 64%
rename from .github/workflows_disabled
rename to .github/workflows/ci.yml
index 9292384..fca6f8f 100644
--- a/.github/workflows_disabled
+++ b/.github/workflows/ci.yml
@@ -6,12 +6,15 @@ on:
   pull_request:
     branches: [main, dev]
 
+permissions:
+  contents: read
+
 jobs:
   build:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ['3.8', '3.9', '3.10', '3.11']
+        python-version: ['3.9', '3.10', '3.11', '3.12']
     steps:
       - uses: actions/checkout@v4
 
@@ -25,13 +28,10 @@ jobs:
           python -m pip install --upgrade pip
           pip install .[dev]
 
-      - name: Lint with flake8
+      - name: Lint with ruff
         run: |
-          pip install flake8
-          flake8 spinstep --count --select=E9,F63,F7,F82 --show-source --statistics
-          flake8 spinstep --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+          ruff check spinstep/
 
       - name: Test with pytest
         run: |
-          pip install pytest
           pytest tests/
diff --git a/dev-requirements.txt b/dev-requirements.txt
index e6341fc..37eec1c 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -1,16 +1,7 @@
-# Optional scientific stack
-matplotlib>=3.7
-numba>=0.57
-cython>=0.29
-cupy
-
-# Optional GPU tooling
-pycuda
-
 # Testing
 pytest
 
-# Optional Code quality / tooling
+# Code quality / tooling
 black
 ruff
 mypy
diff --git a/spinstep/discrete.py b/spinstep/discrete.py
index 3e6418d..48ab185 100644
--- a/spinstep/discrete.py
+++ b/spinstep/discrete.py
@@ -6,7 +6,7 @@
 
 from __future__ import annotations
 
-from typing import Any, Optional, Union
+from typing import Any
 
 import numpy as np
 from numpy.typing import ArrayLike
diff --git a/spinstep/node.py b/spinstep/node.py
index e95182b..e4cbd6d 100644
--- a/spinstep/node.py
+++ b/spinstep/node.py
@@ -6,7 +6,7 @@
 
 from __future__ import annotations
 
-from typing import List, Optional, Sequence, Union
+from typing import List, Optional, Sequence
 
 import numpy as np
 from numpy.typing import ArrayLike
diff --git a/tests/test_utils.py b/tests/test_utils.py
index d8c1102..650885a 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -210,3 +210,29 @@ def test_relative_spin_nonzero(self):
         q = get_relative_spin(n1, n2)
         # Should be a unit quaternion
         assert np.linalg.norm(q) == pytest.approx(1.0, abs=1e-6)
+
+
+# ===== get_unique_relative_spins tests (requires healpy) =====
+
+
+class TestGetUniqueRelativeSpins:
+    def test_returns_list_of_unit_quaternions(self):
+        """Unique spins should be a list of unit quaternions."""
+        hp = pytest.importorskip("healpy", reason="healpy not installed")
+        from spinstep.utils.quaternion_utils import get_unique_relative_spins
+
+        nside = 1
+        npix = hp.nside2npix(nside)
+        # Build nodes with orientations derived from HEALPix pixel directions
+        nodes = []
+        for i in range(npix):
+            theta, phi = hp.pix2ang(nside, i, nest=True)
+            q = R.from_euler("yz", [theta, phi], degrees=False).as_quat()
+            nodes.append(Node(f"n{i}", q))
+
+        spins = get_unique_relative_spins(nodes, nside=nside, nest=True)
+        assert isinstance(spins, list)
+        assert len(spins) > 0
+        for q in spins:
+            assert np.linalg.norm(q) == pytest.approx(1.0, abs=1e-6)
+            assert q[3] >= 0  # canonical form (w >= 0)