Event Sourcing

The event-sourcing skill enables AI agents to record all state changes as a sequence of immutable events rather than storing current state snapshots. This approach allows systems to reconstruct past states, audit actions, and derive new states by replaying the event log.

When to use it

• Implementing financial ledgers where every transaction must be auditable and irreversible.
• Building collaborative editing tools that need to resolve conflicts by replaying user actions.
• Creating debugging environments where you can rewind a system to a specific point in time.
• Designing data pipelines that require deriving current views from historical change streams.

Key capabilities

• Stores state transitions as an append-only log of events.
• Reconstructs historical system states by replaying event sequences.
• Enables full audit trails for compliance and debugging purposes.
• Supports multiple read models derived from the same event stream.

Example prompts

"Design a banking ledger that uses event sourcing to track every deposit and withdrawal as an immutable event." "Create a collaborative document editor where conflicts are resolved by replaying user edit events in chronological order." "Build a system that can rewind a user's shopping cart to the state it was in 10 minutes ago using an event log."

Tips & gotchas

Event sourcing requires careful planning for schema evolution, as changing event structures can break historical data interpretation. Ensure your agents understand that current state is not stored directly but must be calculated by aggregating all prior events.