Add a validation endpoint to our project planner so that, before a plan is saved, the backend can verify that the submitted task dependencies don’t form a loop. The frontend will POST a JSON payload with tasks and their dependency links; the service should build a directed graph in memory and check for cycles (e.g., A → B → C → A). If a cycle is found, return a 400 with a clear message and the list or path of task IDs involved; otherwise return success. This needs to handle large plans without timing out. We’re on Java/Spring Boot with PostgreSQL, but this endpoint only validates the payload and doesn’t write to the database.