# Meta Cheat Sheet

> Quick reference for BookStore code rules and patterns. Use this when you need a fast lookup of conventions for IDs (Guid.CreateVersion7), timestamps (DateTimeOffset.UtcNow), event naming, logging (LoggerMessage), caching, or multi-tenancy. DO NOT USE FOR: step-by-step workflows — use the relevant scaffold skill instead.

- Skill: `majiayu000/meta-cheat-sheet` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add majiayu000/meta-cheat-sheet`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/meta-cheat-sheet/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/meta-cheat-sheet

---


# BookStore Cheat Sheet

## IDs & Timestamps
```csharp
var id = Guid.CreateVersion7();           // ✅ UUIDv7
var now = DateTimeOffset.UtcNow;          // ✅ UTC timestamp
```

## Event (past tense, record)
```csharp
public record BookAdded(Guid Id, string Title, decimal Price);
```

## Command (record)
```csharp
public record AddBookCommand(string Title, decimal Price);
```

## Aggregate Apply Method
```csharp
public void Apply(BookAdded @event)
{
    Id = @event.Id;
    Title = @event.Title;
}
```

## Handler (static, Wolverine)
```csharp
public static class AddBookHandler
{
    public static BookAdded Handle(AddBookCommand cmd) =>
        new(Guid.CreateVersion7(), cmd.Title, cmd.Price);
}
```

## HybridCache Query
```csharp
var result = await cache.GetOrCreateAsync(
    $"books:{culture}",
    async ct => await session.Query<BookProjection>().ToListAsync(ct),
    tags: [CacheTags.BookList],
    cancellationToken: ct);
```

## Cache Invalidation
```csharp
await cache.RemoveByTagAsync(CacheTags.BookList, ct);
```

## SSE Notification
```csharp
public record BookUpdatedNotification(Guid Id) : IDomainEventNotification;
```

## TUnit Test
```csharp
[Test]
public async Task Should_Create_Book()
{
    var result = await client.CreateBookAsync(request);
    await Assert.That(result.Id).IsNotNull();
}
```

## Namespace
```csharp
namespace BookStore.ApiService.Handlers;  // ✅ File-scoped
```

## Related Skills
- `/wolverine__guide` - All Wolverine write operations (create, update, delete)
- `/marten__guide` - Aggregates, projections, and query endpoints