Identity details type generation

The proxy generator can automatically discover and generate TypeScript types for your custom identity details. This enables type-safe access to identity information in your frontend application.

Overview

When you implement a strongly-typed identity details provider using IProvideIdentityDetails<TDetails>, the proxy generator will:

1. Discover all implementations of IProvideIdentityDetails<TDetails> in your assemblies
2. Extract the TDetails type parameter
3. Generate TypeScript representations of these types
4. Include them in the standard proxy output alongside commands and queries

The generic interface

Arc provides this generic interface declaration (an API reference excerpt, not a type to redeclare in your application):

public interface IProvideIdentityDetails<TDetails> : IProvideIdentityDetails
    where TDetails : class;

This interface extends the base IProvideIdentityDetails interface but adds type information that the proxy generator can discover and use.

For detailed information on implementing identity providers, see the Identity documentation.

How discovery works

The proxy generator scans all loaded assemblies for classes that:

1. Are concrete (non-abstract) classes
2. Implement IProvideIdentityDetails<TDetails>
3. Have a valid type argument for TDetails

The TDetails type is then processed like any other complex type, generating a corresponding TypeScript class with serialization metadata by default. Plain interface output is a separate CLI mode; see library mode.

Generated artifacts

For each identity details type discovered, the generator creates:

1. TypeScript class: A model matching the C# type structure, with @field metadata for deserialization
2. Nested Types: Any complex types referenced by the details type
3. Export entry: Added to the appropriate index.ts file when index generation is enabled

Benefits of using the generic interface

Feature	IProvideIdentityDetails	IProvideIdentityDetails<TDetails>
Runtime behavior	Identical	Identical
Details-type discovery	No generic details type declared	Generic argument identifies the type to generate
Proxy generation	No type generated	TypeScript type generated
Frontend type safety	Manual typing required	Automatic type safety

Best practices

1. Use the Generic Interface: Always prefer IProvideIdentityDetails<TDetails> over the base interface to enable proxy generation.

2. Keep Types Simple: Identity details types should be simple DTOs without complex logic or dependencies.

3. Avoid Sensitive Data: Never include sensitive information like tokens or passwords in identity details.

4. Use Records: Consider using C# records for immutable identity detail types.

Frontend integration

The generated TypeScript types can be used with the identity system in @cratis/arc/identity. The types ensure that your frontend code has compile-time type safety when accessing identity details.

Pass the generated class as the details constructor when configuring React identity. A TypeScript interface alone carries no runtime field metadata. Identity details are client-visible UI data, not an authorization boundary.