Allow unsigned padded history dtypes

src/pyrecest/utils/history_recorder.py

@@ -7,6 +7,8 @@
 from math import nan
 from typing import Any
 
+import numpy as np
+
 from pyrecest import backend
 
 # pylint: disable=no-name-in-module,no-member
@@ -46,6 +48,13 @@ def _validate_bool_flag(value: Any, name: str) -> bool:
 
 
 def _is_invalid_padded_history_dtype(dtype: Any) -> bool:
+    try:
+        dtype_kind = np.dtype(dtype).kind
+    except (TypeError, ValueError):
+        dtype_kind = None
+    if dtype_kind is not None:
+        return dtype_kind in {"b", "c", "O", "U", "S", "M", "m"}
+
     dtype_name = str(dtype).lower()
     return (
         "bool" in dtype_name

tests/test_history_recorder_unsigned_dtype.py

@@ -0,0 +1,34 @@
+import numpy as np
+import pytest
+
+from pyrecest import backend
+from pyrecest.utils.history_recorder import HistoryRecorder
+
+
+def _as_numpy(value):
+    return backend.to_numpy(value)
+
+
+def _swapped_uint16_dtype():
+    return np.dtype("uint16").newbyteorder("S")
+
+
+def test_padded_history_accepts_non_native_unsigned_integer_arrays():
+    recorder = HistoryRecorder()
+    initial = np.array([1, 2], dtype=_swapped_uint16_dtype())
+
+    history = recorder.register("counts", initial, pad_with_nan=True)
+
+    assert _as_numpy(history).tolist() == [[1.0], [2.0]]
+
+    updated = recorder.record("counts", np.array([3], dtype=_swapped_uint16_dtype()))
+
+    expected = np.array([[1.0, 3.0], [2.0, np.nan]])
+    assert np.allclose(_as_numpy(updated), expected, equal_nan=True)
+
+
+def test_padded_history_still_rejects_unicode_arrays():
+    recorder = HistoryRecorder()
+
+    with pytest.raises(TypeError, match="padded history values must be real numeric"):
+        recorder.register("bad", np.array(["1"], dtype=np.dtype("U1")), pad_with_nan=True)