Carry the level everywhere a position is drawn, and gate it per occurrence

scripts/site_imports/wjf/harness.py

@@ -100,6 +100,22 @@ class Harness:
         self.ids = IdMap(idmap_path or default)
         self.source = Source()
         self.errors = []
+        self._defaultlevelid = None
+
+    @property
+    def defaultlevelid(self):
+        """The level imported map positions belong to (ADR-017).
+
+        The legacy schema predates levels: it has ONE floor plan, so every
+        mapleft/maptop it carries is a coordinate on this site's default level.
+        Importing them without a level produces markers the map refuses to draw
+        - it will not guess a drawing for coordinates that do not name one.
+        """
+        if self._defaultlevelid is None:
+            from shopdb.core.models import MapLevel
+            level = MapLevel.default_level()
+            self._defaultlevelid = level.levelid if level else None
+        return self._defaultlevelid
 
     def _silence_sql_logging(self):
         import logging