Fix GSDReader TypeError when indexing with NumPy scalar integers

package/AUTHORS

@@ -270,6 +270,7 @@ Chronological list of authors
 2026
   - Mohammad Ayaan
   - Khushi Phougat
+  - Suriya Sureshkumar
 
 External code
 -------------

package/MDAnalysis/coordinates/GSD.py

@@ -128,7 +128,10 @@ def _reopen(self):
         self.open_trajectory()
 
     def _read_frame(self, frame):
+        # Convert numpy integer types to Python int for gsd compatibility
+        # GSD's HOOMDTrajectory only accepts Python int, not np.int64
         try:
+            frame = int(frame)
             myframe = self._file[frame]
         except IndexError:
             raise IOError from None

testsuite/MDAnalysisTests/coordinates/test_gsd.py

@@ -22,6 +22,7 @@
 #
 import os
 
+import numpy as np
 import pytest
 from numpy.testing import assert_almost_equal
 
@@ -73,3 +74,29 @@ def test_gsd_dimensions(self, GSD_U):
     def test_gsd_data_step(self, GSD_U):
         assert GSD_U.trajectory[0].data["step"] == 0
         assert GSD_U.trajectory[1].data["step"] == 500
+
+    def test_gsd_numpy_int_indexing(self, GSD_U):
+        """Test that GSDReader accepts numpy integer types (Issue #5224).
+
+        The parallelization framework generates frame indices as np.int64,
+        but GSD's HOOMDTrajectory only accepts Python int. This test ensures
+        the reader properly converts numpy scalar integers.
+        """
+        # Test with np.int64 (most common from numpy arrays)
+        ts = GSD_U.trajectory[np.int64(0)]
+        assert ts.frame == 0
+
+        # Test with negative indexing
+        ts = GSD_U.trajectory[np.int64(-1)]
+        assert ts.frame == 1
+
+        # Test with other numpy integer types
+        ts = GSD_U.trajectory[np.int32(1)]
+        assert ts.frame == 1
+
+        # Directly test _read_frame with numpy integers to ensure coverage
+        ts = GSD_U.trajectory._read_frame(np.int64(0))
+        assert ts.frame == 0
+
+        ts = GSD_U.trajectory._read_frame(np.int32(1))
+        assert ts.frame == 1

testsuite/MDAnalysisTests/coordinates/test_xdr.py

@@ -1058,7 +1058,6 @@ def test_persistent_offsets_readonly(self, tmpdir, trajectory):
     def test_offset_lock_created(self, traj):
         assert os.path.exists(XDR.offsets_filename(traj, ending="lock"))
 
-
 class TestXTCReader_offsets(_GromacsReader_offsets):
     __test__ = True
     filename = XTC