fix(multiplayer): validate legacy connection leases

server/migrations/0012_validate_connection_leases.sql

@@ -0,0 +1,5 @@
+-- Migration 0011 used NOT VALID so the new check protected concurrent writes
+-- while its backfill completed. Validate separately so an upgraded database
+-- cannot silently retain an impossible pre-lease connection state.
+ALTER TABLE match_participants
+    VALIDATE CONSTRAINT match_participants_connection_lease;

server/migrations/down/0012_validate_connection_leases.sql

@@ -0,0 +1 @@
+-- Constraint validation changes no schema and is intentionally irreversible.

server/migrations/test_migration.py

@@ -10,6 +10,7 @@ QUOTAS_SQL = (Path(__file__).parent / "0007_allocation_quotas.sql").read_text()
 ARENAS_SQL = (Path(__file__).parent / "0008_match_arena_paths.sql").read_text()
 ALLOCATION_ARENAS_SQL = (Path(__file__).parent / "0009_allocation_arena_paths.sql").read_text()
 INITIAL_CONNECT_READY_SQL = (Path(__file__).parent / "0010_initial_connect_ready_at.sql").read_text()
+CONNECTION_LEASE_VALIDATION_SQL = (Path(__file__).parent / "0012_validate_connection_leases.sql").read_text()
 
 
 class MigrationTest(unittest.TestCase):
@@ -78,6 +79,9 @@ class MigrationTest(unittest.TestCase):
         self.assertIn("ADD COLUMN initial_connect_ready_at TIMESTAMPTZ", INITIAL_CONNECT_READY_SQL)
         self.assertIn("state IN ('ASSIGNMENT_READY', 'ASSIGNED', 'CONNECTING')", INITIAL_CONNECT_READY_SQL)
 
+    def test_connection_lease_backfill_is_validated_for_legacy_rows(self):
+        self.assertIn("VALIDATE CONSTRAINT match_participants_connection_lease", CONNECTION_LEASE_VALIDATION_SQL)
+
 
 if __name__ == "__main__":
     unittest.main()