Make chat_backend migrations a single chain.

0034_waitlistentry and 0034_customuser_use_conversation_context both depended on 0033, so the graph had two leaves. Waitlist is now 0035 and depends on the customuser migration.

Closes #76

llm_be/chat_backend/migrations/0035_waitlistentry.py

@@ -7,7 +7,7 @@ from django.db import migrations, models
 class Migration(migrations.Migration):
 
     dependencies = [
-        ("chat_backend", "0033_agentrun_agentstep"),
+        ("chat_backend", "0034_customuser_use_conversation_context"),
     ]
 
     operations = [

llm_be/chat_backend/tests/test_migration_graph.py

@@ -0,0 +1,14 @@
+from django.db import connection
+from django.db.migrations.loader import MigrationLoader
+from django.test import TestCase
+
+
+class MigrationGraphTests(TestCase):
+    def test_chat_backend_has_a_single_leaf(self):
+        loader = MigrationLoader(connection, ignore_no_migrations=True)
+        leaves = [name for app, name in loader.graph.leaf_nodes() if app == "chat_backend"]
+        self.assertEqual(leaves, ["0035_waitlistentry"])
+
+        node = loader.graph.nodes[("chat_backend", "0035_waitlistentry")]
+        parents = [name for app, name in node.dependencies if app == "chat_backend"]
+        self.assertEqual(parents, ["0034_customuser_use_conversation_context"])