presenter/CLAUDE.md

# presenter

Shared Go library for GraphQL error presentation with coded errors.

## Shared Documentation

@../docs/claude/architecture.md
@../docs/claude/go-services.md
@../docs/claude/graphql.md
@../docs/claude/conventions.md

## Library Information

### Purpose

Provides a standardized GraphQL error presenter that handles coded errors across all microservices. Converts internal error codes to GraphQL error extensions.

### Usage

```go
import "git.unbound.se/shiny/presenter"

// Create error presenter with valid codes and entities
errorPresenter := presenter.New(logger, validCodes, validEntities, internalErrorCode)

// Use in gqlgen server config
srv := handler.NewDefaultServer(generated.NewExecutableSchema(cfg))
srv.SetErrorPresenter(errorPresenter)
```

### Key Types

- `CodedError` - Error type with code, entity, and params
- `Code` - Error code type
- `Entity` - Error entity type

### Error Extensions

Errors are presented with extensions:
- `code` - The error code (mapped to valid codes or internal error)
- `errorEntity` - The entity related to the error (optional)
- `params` - Additional error parameters (optional)