Prefect Cloud uses UUID version 7 (UUIDv7) for flow run IDs. This is particularly significant because: 1. UUIDv7 is time-ordered, which means the IDs are sortable by creation time 2. This makes it efficient for querying and organizing flow runs chronologically 3. It provides both uniqueness and temporal ordering in a single identifier This is part of Prefect's broader use of UUIDv7 for time-series-like entities (including runs, states, and logs) in the system. The implementation is defined in Prefect's base model schemas, which ensure consistent ID generation across the platform. You can see this in action when you look at any flow run ID - they'll follow the UUIDv7 specification, which includes a timestamp component while maintaining uniqueness guarantees.