Agent skill · software engineering · aj-geddes
event-sourcing
Implement event sourcing and CQRS patterns using event stores, aggregates, and projections. Use when building audit trails, temporal queries, or systems requiring full history.
Why this skill is useful
Provides specific implementation patterns and best practices for event sourcing and CQRS that the AI wouldn't reliably generate on its own.
What it needs
About 1k tokens when loaded. Last updated 2026-03-04. 307 stars on the source repository.
What this skill does
Event Sourcing Table of Contents Overview When to Use Quick Start Reference Guides Best Practices Overview Store state changes as a sequence of events rather than the current state, enabling temporal queries, audit trails, and event replay. When to Use Audit trail requirements Temporal queries (state at any point in time) Event-driven microservices CQRS implementations Financial systems Complex domain models Debugging and analysis Compliance and regulation Quick Start Minimal working example: Reference Guides Detailed implementations in the references/ directory: Guide Contents --- --- Event Store (TypeScript) Event Store (TypeScript) Projections (Read Models) Projections (Read Models) Event Store with PostgreSQL Event Store with PostgreSQL Snapshots for Performance Snapshots for Performance Best Practices ✅ DO Store events immutably Version your events Use optimistic concurrency Create snapshots for performance Use projections for queries Keep events small and focused Include metadata (timestamp, user, etc.) Handle event versioning/migration ❌ DON'T Mutate past events Store current state only Skip concurrency checks Query event store for reads Make events too large Forget about event schema evolution
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills aj-geddes/event-sourcing