Ask HN: Has anyone implemented branching for event streams?

I'm working on GenesisDB, an event sourcing database, and have been thinking about adding git-like branches for event streams.

The idea came from user requests. Several people asked for the ability to:

- Test scenarios with production data without polluting the main stream

- Explore "what if" questions in isolation

- Roll back a series of events that shouldn't have happened

The design: create a branch (O(1), just a pointer), commit events to it in isolation, then merge back to main or discard. Hash chain gets recalculated on merge, and merges are logged as system events for audit.

I'm curious:

- Has anyone seen this pattern before in other event stores?

- What use cases would this unlock for you?

- Any gotchas I should watch out for?