diff --git a/server/utils/schema.ts b/server/utils/schema.ts
index aef413f..7e8f50f 100644
--- a/server/utils/schema.ts
+++ b/server/utils/schema.ts
@@ -20,4 +20,8 @@ create table if not exists tasks (
 
 create index if not exists idx_tasks_list_id on tasks(list_id);
 create index if not exists idx_tasks_unconsumed on tasks(consumed) where consumed = false;
+
+-- Multi-user plumbing: rows are owned by a Zitadel sub. NULL = legacy/unowned (pre-multi-user).
+alter table lists add column if not exists owner_id text;
+alter table tasks add column if not exists owner_id text;
 `;