Relationship inverse guard, audit command, widened direction fixer

shopdb/core/api/assets.py

@@ -610,6 +610,12 @@ def _add_propagated(sourceid, targetid, rel, created):
         return
     if _relationship_exists(sourceid, targetid, rel.relationshiptypeid):
         return
+    # Never fan out INTO an existing inverse. The same one-way rule the create
+    # path enforces: if target-T->source is already stored, adding source-T->
+    # target would manufacture a reciprocal pair that no user asked for, on a
+    # rail that is meant to spread one direction across sibling bays.
+    if _relationship_exists(targetid, sourceid, rel.relationshiptypeid):
+        return
     newrel = AssetRelationship(
         sourceassetid=sourceid,
         targetassetid=targetid,
@@ -754,6 +760,14 @@ def create_asset_relationship():
     if not db.session.get(RelationshipType, type_id):
         return error_response(ErrorCodes.NOT_FOUND, f'Relationship type {type_id} not found', http_code=404)
 
+    # An asset cannot relate to itself. It renders as a duplicate row on that
+    # asset's own page (the card lists both ends) and means nothing.
+    if source_id == target_id:
+        return error_response(
+            ErrorCodes.VALIDATION_ERROR,
+            'An asset cannot be related to itself'
+        )
+
     # Check for duplicate relationship
     existing = AssetRelationship.query.filter_by(
         sourceassetid=source_id,
@@ -768,6 +782,32 @@ def create_asset_relationship():
             http_code=409
         )
 
+    # And it cannot relate BOTH WAYS on a directional type. Only one direction
+    # can be true - a PC drives a machine, never the reverse - but the check
+    # above is keyed on (source, target, type), so the inverse used to insert
+    # cleanly and both rows then rendered on both asset pages. The dialog offers
+    # an `incoming` direction, so this is reachable by hand, and the legacy
+    # import stores controls the wrong way round.
+    #
+    # Symmetric types are exempt: they store both directions ON PURPOSE and the
+    # card collapses them to one entry per peer.
+    reltype = db.session.get(RelationshipType, type_id)
+    if reltype is not None and reltype.isdirectional:
+        inverse = AssetRelationship.query.filter_by(
+            sourceassetid=target_id,
+            targetassetid=source_id,
+            relationshiptypeid=type_id
+        ).first()
+        if inverse is not None:
+            return error_response(
+                ErrorCodes.CONFLICT,
+                f"The reverse of this relationship already exists "
+                f"(relationship {inverse.relationshipid}). A "
+                f"'{reltype.relationshiptype}' link points one way only - "
+                f"remove the existing one first if the direction is wrong.",
+                http_code=409
+            )
+
     rel = AssetRelationship(
         sourceassetid=source_id,
         targetassetid=target_id,