Fix off-by-one in remove_artifacts zeros mode leaving last artifact sample un-zeroed

src/spikeinterface/preprocessing/remove_artifacts.py

@@ -274,12 +274,12 @@ def get_traces(self, start_frame, end_frame, channel_indices):
                 if pad is None:
                     traces[trig, :] = 0
                 else:
-                    if trig - pad[0] > 0 and trig + pad[1] < end_frame - start_frame:
+                    if trig - pad[0] >= 0 and trig + pad[1] < end_frame - start_frame:
                         traces[trig - pad[0] : trig + pad[1] + 1, :] = 0
                     elif trig - pad[0] <= 0 and trig + pad[1] >= end_frame - start_frame:
                         traces[:] = 0
                     elif trig - pad[0] <= 0:
-                        traces[: trig + pad[1], :] = 0
+                        traces[: trig + pad[1] + 1, :] = 0
                     elif trig + pad[1] >= end_frame - start_frame:
                         traces[trig - pad[0] :, :] = 0
         elif self.mode in ["linear", "cubic"]:

src/spikeinterface/preprocessing/tests/test_remove_artifacts.py

@@ -85,5 +85,47 @@ def test_remove_artifacts():
     )
 
 
+def test_remove_artifacts_zeros_boundary():
+    """
+    Regression test for off-by-one bug in zeros mode boundary handling.
+
+    When get_traces is called with a window wider than the artifact (so the artifact
+    start aligns with or precedes the window start), the last sample of the artifact
+    period must also be zeroed. Previously, ``traces[:trig + pad[1]]`` was used
+    instead of ``traces[:trig + pad[1] + 1]``, leaving the very last artifact sample
+    un-zeroed.
+    """
+    rec = generate_recording(durations=[10.0])
+    rec.annotate(is_filtered=True)
+
+    trigger = 15000
+    ms = 10
+    fs = rec.get_sampling_frequency()
+    ms_frames = int(ms * fs / 1000)
+
+    rec_rmart = remove_artifacts(rec, [trigger], ms_before=ms, ms_after=ms)
+
+    # Request a window that starts exactly at trigger - ms_frames (so trig - pad[0] == 0)
+    # but ends *beyond* trigger + ms_frames.  This exercises the boundary branch where
+    # `trig - pad[0] <= 0` but the artifact end lies strictly inside the chunk.
+    extra = 10
+    traces = rec_rmart.get_traces(
+        start_frame=trigger - ms_frames,
+        end_frame=trigger + ms_frames + extra,
+    )
+
+    # The artifact window [trigger - ms_frames, trigger + ms_frames] must be all zeros,
+    # including the last sample at index 2 * ms_frames (previously missed).
+    zeroed_artifact_traces = traces[: 2 * ms_frames + 1, :]
+    assert not np.any(zeroed_artifact_traces), (
+        "Last sample of artifact window was not zeroed (off-by-one boundary bug)"
+    )
+
+    # Samples beyond the artifact window should be non-zero (from the underlying recording)
+    beyond_artifact = traces[2 * ms_frames + 1 :, :]
+    assert np.any(beyond_artifact), "Samples beyond the artifact window should not be zero"
+
+
 if __name__ == "__main__":
     test_remove_artifacts()
+    test_remove_artifacts_zeros_boundary()