fix(OP#9528): use drop_nulls subset in create_track_segments to preserve null-geo segments

drop_nulls() without a subset dropped every row where any column was null,
including segments from null-padded tracks (geo columns present but null).
This caused tracks without geo data in a mixed dataset to have zero segments
in the geometry store, making them invisible to intersection detection.

Restrict the drop to the non-geo shifted columns whose nulls exclusively
mark the first (incomplete) detection row of each track.

Author: randy-seng

OTAnalytics/plugin_datastore/track_geometry_store/polars_geometry_store.py

@@ -185,7 +185,17 @@ def create_track_segments(df: pl.DataFrame) -> pl.DataFrame:
             pl.col(H).shift(1).over(TRACK_ID).alias(START_H),
         ]
         + geo_columns
-    ).drop_nulls()  # Remove rows where shift resulted in null (first rows per track)
+    ).drop_nulls(
+        subset=[
+            START_OCCURRENCE,
+            START_X,
+            START_Y,
+            START_W,
+            START_H,
+        ]
+        # Only drop on non-geo shifted columns. Geo columns may legitimately be
+        # null (null-padded datasets) and must not cause valid segments to be dropped.
+    )
 
     geo_select = [END_GEO_X, END_GEO_Y, START_GEO_X, START_GEO_Y] if has_geo else []
 

tests/unit/OTAnalytics/plugin_datastore/track_geometry_store/test_polars_geometry_store.py

@@ -827,6 +827,17 @@ def test_segments_omit_geo_columns_when_only_geo_x_present(self) -> None:
         result = create_track_segments(df_only_x)
         assert START_GEO_X not in result.columns
 
+    def test_segments_preserved_when_geo_columns_have_null_values(self) -> None:
+        given = create_segment_geo_given()
+        df_null_geo = given.df_without_geo.with_columns(
+            pl.lit(None, dtype=pl.Float64).alias(track.GEO_X),
+            pl.lit(None, dtype=pl.Float64).alias(track.GEO_Y),
+        )
+        result = create_track_segments(df_null_geo)
+        assert len(result) == 2
+        assert result[START_GEO_X].is_null().all()
+        assert result[END_GEO_X].is_null().all()
+
 
 @dataclass
 class LineIntersectionGeoGiven: