fix(tables): make calc_bbox_intersection safety_margin actually apply

src/openparse/tables/table_transformers/geometry.py

@@ -13,26 +13,15 @@ def calc_bbox_intersection(bbox1, bbox2, safety_margin=5.0):
     ):
         raise ValueError("Bounding boxes must have non-zero width and height.")
 
-    # Expand bounding boxes
-    x1_expanded_min = min(bbox1[0], bbox2[0]) - safety_margin
-    y1_expanded_min = min(bbox1[1], bbox2[1]) - safety_margin
-    x2_expanded_max = max(bbox1[2], bbox2[2]) + safety_margin
-    y2_expanded_max = max(bbox1[3], bbox2[3]) + safety_margin
-
-    # Check if expanded boxes intersect
-    if (
-        x2_expanded_max <= max(bbox1[0], bbox2[0])
-        or x1_expanded_min >= min(bbox1[2], bbox2[2])
-        or y2_expanded_max <= max(bbox1[1], bbox2[1])
-        or y1_expanded_min >= min(bbox1[3], bbox2[3])
-    ):
-        return None
-
-    # Calculate and return the actual intersection based on original boxes
-    x1 = max(bbox1[0], bbox2[0])
-    y1 = max(bbox1[1], bbox2[1])
-    x2 = min(bbox1[2], bbox2[2])
-    y2 = min(bbox1[3], bbox2[3])
+    # Expand each box by the safety margin, then intersect the expanded boxes,
+    # so two boxes that are within `safety_margin` of each other are treated as
+    # overlapping. This matches the tolerance used by ``Element.overlaps`` and
+    # makes ``safety_margin`` actually take effect: expanding a box on both
+    # sides shifts each edge of the intersection outward by the margin.
+    x1 = max(bbox1[0], bbox2[0]) - safety_margin
+    y1 = max(bbox1[1], bbox2[1]) - safety_margin
+    x2 = min(bbox1[2], bbox2[2]) + safety_margin
+    y2 = min(bbox1[3], bbox2[3]) + safety_margin
 
     # Only return the intersection if it's valid
     if x2 > x1 and y2 > y1:

src/tests/tables/transformers/test_geometry.py

@@ -9,12 +9,16 @@
     [
         # Test case 1: Intersecting without margin
         ((10, 10, 20, 20), (15, 15, 25, 25), 0, (15, 15, 20, 20)),
-        # Test case 2: Intersecting with margin - adjusted to expect None for a point intersection
-        ((10, 10, 20, 20), (20, 20, 30, 30), 5, None),  # Adjusted expectation
+        # Test case 2: Boxes touching at a corner are within the margin, so the
+        # margin-expanded intersection is returned.
+        ((10, 10, 20, 20), (20, 20, 30, 30), 5, (15, 15, 25, 25)),
         # Test case 3: Not intersecting, no margin
         ((10, 10, 20, 20), (25, 25, 35, 35), 0, None),
-        # Test case 4: Not intersecting, with margin
-        ((10, 10, 20, 20), (26, 26, 36, 36), 5, None),
+        # Test case 4: Boxes 6 apart are within a margin of 5 on each side, so
+        # the expanded intersection is returned.
+        ((10, 10, 20, 20), (26, 26, 36, 36), 5, (21, 21, 25, 25)),
+        # Test case 5: Boxes far apart stay non-intersecting even with a margin.
+        ((0, 0, 10, 10), (100, 100, 110, 110), 5, None),
     ],
 )
 def test_calc_bbox_intersection(bbox1, bbox2, safety_margin, expected):