Last night

pipeline/transform/postcode_boundaries/voronoi.py

@@ -75,6 +75,9 @@ def compute_voronoi_regions(
     n_real = len(pts)
     pc_polys: dict[str, list[Polygon]] = defaultdict(list)
 
+    if not boundary.is_valid:
+        boundary = make_valid(boundary)
+
     for i in range(n_real):
         region_idx = vor.point_region[i]
         region = vor.regions[region_idx]
@@ -100,6 +103,8 @@ def _equal_split_fallback(
     postcodes: list[str], boundary: Polygon | MultiPolygon
 ) -> dict[str, Polygon | MultiPolygon]:
     """Split boundary into roughly equal horizontal strips, one per postcode."""
+    if not boundary.is_valid:
+        boundary = make_valid(boundary)
     min_x, min_y, max_x, max_y = boundary.bounds
     n = len(postcodes)
     result = {}