Cratis Arc proxies — generate identity details

Cratis Arc generates TypeScript models for custom identity details when a provider implements IProvideIdentityDetails<TDetails>. Use this interface to keep the frontend’s details model tied to the C# type instead of maintaining a separate TypeScript definition.

Overview

The generic argument TDetails tells the generator which model the provider returns. With proxy generation configured, that model and the types it references join the output alongside commands and queries. You do not need a command or query to reference the details model for it to be discovered.

The generic interface

Arc provides the following interface. This is an API reference excerpt, not a type to redeclare in your application:

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

The generic interface extends IProvideIdentityDetails without adding methods. Your provider still implements the base interface’s Provide method; TDetails supplies the type information used during generation.

If you have not implemented a provider yet, follow the Identity documentation, then return here to connect its details type to the frontend.

How discovery works

The proxy generator scans the project assemblies it loads for concrete, non-abstract classes implementing IProvideIdentityDetails<TDetails>. It extracts TDetails from each matching provider and processes it like other complex model types.

By default, the result is a TypeScript class with serialization metadata: @field decorators that tell the runtime how to reconstruct its properties from JSON. Plain interface output is a separate option, not the default; library mode controls which additional types are collected.

Generated artifacts

For each discovered details type, the default output includes:

• A TypeScript model class matching the C# type’s properties, with @field metadata for deserialization.
• Models for referenced complex types, subject to the usual type mappings and exclusions.
• An export in the appropriate index.ts file when index generation is enabled.

Keep these files generator-owned. When the C# details type changes, regenerate the proxies and compile the frontend rather than editing the generated class.

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	Provider does not identify a details type	Details type included in generation
Frontend typing	Handwritten or discovered elsewhere	Use the generated details model

Best practices

Use the generic interface when your provider returns a known details type. Keep that type focused on the data the UI needs; the generator produces a model, not a translation of C# methods or business logic. A C# record is one way to represent an immutable details payload.

Identity details are sent to the client. Do not put passwords, tokens or other secrets in them, and enforce authorization on the backend rather than trusting the UI’s copy.

Frontend integration

Use the generated class with the identity system in @cratis/arc/identity. For React consumers, pass it as the details constructor when configuring React identity; that guide shows how to read the details and handle loading or absent values.

The class provides both a TypeScript shape for frontend code and runtime field metadata for deserialization. A TypeScript interface alone has no constructor or field metadata, and a type annotation does not guarantee that the backend supplied details.