relationships: the cleanup tools stop acting on links that were deleted

Deleting a relationship is soft, so the row survives with isactive False, and
three things read them without knowing that.

Re-adding a deleted link answered 409 "this relationship already exists" about a
link the page no longer shows, and there was no way forward from the UI at all -
the row cannot simply be inserted again, since the triple is unique.
Reactivating IS the create for an inactive row.

The inverse guard blocked on a deleted inverse, which made "remove the existing
one first" - the instruction in its own message - fail to unblock anything.

fix-controls-direction retired the reversed row whenever a correctly-directed
one existed, without checking whether that one was itself deleted. So it removed
the only live link and reported a successful clean-up. It now reactivates the
row pointing the right way before retiring the one pointing the wrong way.

These are the commands the docs tell an operator to run against production.

shopdb/cli/__init__.py

@@ -738,6 +738,13 @@ def fix_controls_direction():
             relationshiptypeid=controls.relationshiptypeid,
         ).first()
         if duplicate:
+            # The correctly-directed row exists - but it may itself be soft
+            # deleted, and deletion here IS soft. Retiring this row without
+            # looking left the pair with NO live link, while the command
+            # reported a successful clean-up. Reactivate the one pointing the
+            # right way before retiring the one pointing the wrong way.
+            if not duplicate.isactive:
+                duplicate.isactive = True
             row.isactive = False  # flipped row already exists, retire this one
             deactivated += 1
         else:

shopdb/core/api/assets.py

@@ -768,14 +768,23 @@ def create_asset_relationship():
             'An asset cannot be related to itself'
         )
 
-    # Check for duplicate relationship
+    # Check for duplicate relationship.
+    #
+    # Deleting a relationship is SOFT (isactive = False, see
+    # delete_asset_relationship). The row therefore survives, and this lookup
+    # found it - so deleting a link and adding it back answered 409 "this
+    # relationship already exists" about a link the page no longer shows, with
+    # no way forward from the UI at all. The row cannot simply be inserted
+    # again either: assetrelationships is unique on (source, target, type).
+    #
+    # Reactivating IS the create, for an inactive row.
     existing = AssetRelationship.query.filter_by(
         sourceassetid=source_id,
         targetassetid=target_id,
         relationshiptypeid=type_id
     ).first()
 
-    if existing:
+    if existing and existing.isactive:
         return error_response(
             ErrorCodes.CONFLICT,
             'This relationship already exists',
@@ -798,7 +807,11 @@ def create_asset_relationship():
             targetassetid=source_id,
             relationshiptypeid=type_id
         ).first()
-        if inverse is not None:
+        # isactive, for the same reason as the duplicate check above: a soft
+        # deleted inverse is a link somebody already removed, and blocking on it
+        # made "remove the existing one first" - the instruction in this very
+        # message - fail to unblock anything.
+        if inverse is not None and inverse.isactive:
             return error_response(
                 ErrorCodes.CONFLICT,
                 f"The reverse of this relationship already exists "
@@ -808,14 +821,20 @@ def create_asset_relationship():
                 http_code=409
             )
 
-    rel = AssetRelationship(
-        sourceassetid=source_id,
-        targetassetid=target_id,
-        relationshiptypeid=type_id,
-        notes=data.get('notes')
-    )
-
-    db.session.add(rel)
+    if existing is not None:
+        # The soft-deleted row from the duplicate check. Reuse it: the unique
+        # index on (source, target, type) means there is no second row to add.
+        rel = existing
+        rel.isactive = True
+        rel.notes = data.get('notes')
+    else:
+        rel = AssetRelationship(
+            sourceassetid=source_id,
+            targetassetid=target_id,
+            relationshiptypeid=type_id,
+            notes=data.get('notes')
+        )
+        db.session.add(rel)
     apply_import_timestamps(rel, data)
     db.session.flush()