`SinterCompiledDecoder_BP.decode_shots_bit_packed`: missing `count=` in `np.unpackbits` causes wrong corrections

[RefaatIsmail]

SinterCompiledDecoder_BP.decode_shots_bit_packed: missing count= in np.unpackbits causes wrong corrections

In relay_bp/stim/sinter/decoders.py, line 46:

syndromes = np.unpackbits(
    bit_packed_detection_event_data, bitorder="little", axis=1
).astype(np.uint8)

When num_detectors % 8 != 0, np.unpackbits pads to the nearest byte boundary, producing extra zero columns that participate in BP message passing and silently produce wrong corrections (inflated logical error rate, no exception raised).

Fix

num_detectors = self.check_matrices.check_matrix.shape[0]
syndromes = np.unpackbits(
    bit_packed_detection_event_data, bitorder="little", axis=1, count=num_detectors
).astype(np.uint8)

[trmue]

Sorry for the very late response!

Thank you for bringing this up, I just fixed it.