fix(reconciliation): serialize compute sync and enforce UUID identity

instances/migrations/0012_instance_unique_compute_uuid.py

@@ -0,0 +1,94 @@
+# Generated by Django 4.2.30 on 2026-09-27 10:57
+
+from django.db import migrations, models
+
+
+def deduplicate_instances(apps, schema_editor):
+    Instance = apps.get_model('instances', 'Instance')
+    UserInstance = apps.get_model('accounts', 'UserInstance')
+    from django.db.models import Count, Q
+    import uuid as uuid_mod
+
+    # Assign distinct UUIDs to legacy/corrupt records with null, empty, or whitespace UUIDs
+    # so they are not treated as duplicates or collapsed together
+    empty_uuid_instances = Instance.objects.filter(
+        Q(uuid__isnull=True) | Q(uuid="") | Q(uuid__regex=r"^\s*$")
+    )
+    for inst in empty_uuid_instances:
+        inst.uuid = str(uuid_mod.uuid4())
+        inst.save(update_fields=['uuid'])
+
+    duplicates = (
+        Instance.objects.exclude(uuid__isnull=True).exclude(uuid="")
+        .values('compute_id', 'uuid')
+        .annotate(count=Count('id'))
+        .filter(count__gt=1)
+    )
+    for item in duplicates:
+        instances = list(Instance.objects.filter(
+            compute_id=item['compute_id'],
+            uuid=item['uuid']
+        ).order_by('-id'))
+        primary = instances[0]
+        # Preserve is_template and non-default drbd across duplicate rows
+        merged_is_template = any(getattr(inst, 'is_template', False) for inst in instances)
+        non_default_drbd = next((inst.drbd for inst in instances if inst.drbd and inst.drbd != 'None'), None)
+        updated = False
+        if primary.is_template != merged_is_template:
+            primary.is_template = merged_is_template
+            updated = True
+        if non_default_drbd and primary.drbd != non_default_drbd:
+            primary.drbd = non_default_drbd
+            updated = True
+        if updated:
+            primary.save()
+
+        for dup in instances[1:]:
+            # Reassign or merge UserInstance relationships
+            for ui in UserInstance.objects.filter(instance=dup):
+                existing = UserInstance.objects.filter(instance=primary, user=ui.user).first()
+                if not existing:
+                    ui.instance = primary
+                    ui.save()
+                else:
+                    # Merge permissions with logical OR so no stronger permission is lost
+                    updated = False
+                    if ui.is_change and not existing.is_change:
+                        existing.is_change = True
+                        updated = True
+                    if ui.is_delete and not existing.is_delete:
+                        existing.is_delete = True
+                        updated = True
+                    if ui.is_vnc and not existing.is_vnc:
+                        existing.is_vnc = True
+                        updated = True
+                    if updated:
+                        existing.save()
+                    ui.delete()
+            dup.delete()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('instances', '0011_createinstance_migrateinstance'),
+        ('accounts', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.RunPython(deduplicate_instances, migrations.RunPython.noop),
+        migrations.AlterField(
+            model_name='flavor',
+            name='id',
+            field=models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID'),
+        ),
+        migrations.AlterField(
+            model_name='instance',
+            name='id',
+            field=models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID'),
+        ),
+        migrations.AddConstraint(
+            model_name='instance',
+            constraint=models.UniqueConstraint(fields=('compute', 'uuid'), name='unique_compute_uuid'),
+        ),
+    ]