Support level MultiPolygons

schema/graphql/schema.graphqls

@@ -681,7 +681,7 @@ type Level {
   "GTFS levels.level_name"
   level_name: String
   "An optional geometry describing the footprint of this level"
-  geometry: Polygon!
+  geometry: MultiPolygon!
   "Stops associated with this level"
   stops: [Stop!]
 }
@@ -2169,7 +2169,7 @@ input LevelSetInput {
   "Set GTFS level_index to this value"
   level_index: Float
   "Set level geometry to this value"
-  geometry: Polygon
+  geometry: MultiPolygon
   "Set level parent station to this stop"
   parent: StopSetInput
 }

schema/postgres/migrations/20250916235833_level-multipolygon.up.pgsql

@@ -0,0 +1,17 @@
+BEGIN;
+-- 1. Rename the old column
+ALTER TABLE gtfs_levels
+    RENAME COLUMN geometry TO geometry_old;
+-- 2. Add the new column as MultiPolygon
+ALTER TABLE gtfs_levels
+    ADD COLUMN geometry geography(MultiPolygon, 4326);
+-- 3. Convert Polygon to MultiPolygon and copy data
+UPDATE gtfs_levels
+    SET geometry = CASE
+        WHEN GeometryType(geometry_old) = 'MULTIPOLYGON' THEN geometry_old
+        WHEN GeometryType(geometry_old) = 'POLYGON' THEN ST_Multi(geometry_old::geometry)::geography
+        ELSE NULL
+    END;
+-- 4. Drop the old column
+ALTER TABLE gtfs_levels DROP COLUMN geometry_old;
+COMMIT;

server/model/models.go

@@ -137,7 +137,7 @@ type Shape struct {
 }
 
 type Level struct {
-	Geometry      tt.Polygon
+	Geometry      tt.MultiPolygon
 	ParentStation tt.Key
 	gtfs.Level
 }