Stack
Data and oracles
How an off-chain fact enters the system, and what happens when it is wrong or late.
The decision
Name the source, the signers, the heartbeat, and the fallback. A missing fallback is a design, not an oversight to discover in production.
When a chain is the wrong layer
If a single operator already holds the legal right and the users, a database with permissions is often the better system. Add a ledger when several parties must share a record none of them should silently edit.