Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add mickeyyaya/refactoring-skills --skill event-sourcing-cqrs-patternsgit clone --depth 1 https://github.com/mickeyyaya/refactoring-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/mickeyyaya/refactoring-skills/event-sourcing-cqrs-patterns)<a href="https://agentmods.dev/skills/mickeyyaya/refactoring-skills/event-sourcing-cqrs-patterns"><img src="https://agentmods.dev/badge/skills/mickeyyaya/refactoring-skills/event-sourcing-cqrs-patterns/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/mickeyyaya/refactoring-skills/event-sourcing-cqrs-patterns"><img src="https://agentmods.dev/badge/skills/mickeyyaya/refactoring-skills/event-sourcing-cqrs-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00071 | $0.05062 |
| Opus 5 | $0.00036 | $0.02531 |
| Sonnet 5 | $0.00014 | $0.01012 |
| Haiku 4.5 | $0.00007 | $0.00506 |
Grade A, and why
event-sourcing-cqrs-patterns scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 556 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Event Sourcing and CQRS Patterns
Overview
Traditional CRUD stores only current state — once you update a record, the history is gone. Event Sourcing inverts this: every state change is recorded as an immutable event appended to an event log. The current state is always derived by replaying events. CQRS (Command Query Responsibility Segregation) separates the write side (commands that emit events) from the read side (projections that build optimized query models).
When to use: Audit trail requirements, financial ledgers, collaborative editing, domain-driven systems with complex business rules, systems needing temporal queries ("what was the balance on date X?"), or microservice architectures requiring reliable async integration.
Quick Reference
| Pattern | Core Idea | Primary Red Flag |
|---|---|---|
| Event Store | Append-only log of domain events | Mutable events, missing sequence numbers |
| CQRS | Separate write model (commands) from read model (queries) | Single model that is both read and written |
| Projection / Read Model | Build query-optimized view from events | Projections tightly coupled to event internals |
| Snapshot | Checkpoint aggregate state to skip full replay | Snapshots taken too rarely or too often |
| Aggregate Replay | Rebuild aggregate by replaying its event stream | Loading entire global log instead of per-aggregate stream |
| Event Versioning / Upcasting | Migrate old event schemas to new versions | Breaking schema changes without versioning |
| Eventual Consistency | Accept that read models lag behind the write model | Assuming reads are always current after a write |
| Idempotency / At-Least-Once | Process duplicate events safely | Missing deduplication in event handlers |
Patterns in Detail
1. Event Sourcing Fundamentals — Event Store and Append-Only Log
The event store is the single source of truth. Events are facts — immutable records of things that happened. The event log is append-only: you never update or delete events.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago First seen · 556 lines · 71 tokens per session scan A e0d6a3e75c1c
event-sourcing-cqrs-patterns is a skill published in the GitHub repository mickeyyaya/refactoring-skills (6 stars, last pushed 5mo ago), licensed MIT. It adds 71 tokens to every session and 5,062 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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