DTO rules

DTOs are plain C# types used as nested state, action parameters, action return values, or event payloads.

Supported shape

Use simple public properties:

public sealed class InventoryItem
{
    public string Id { get; set; } = "";
    public string Name { get; set; } = "";
    public int Count { get; set; }
}

Prefer:

• string, bool, numeric types
• enums
• DTO classes and structs
• arrays and lists
• dictionaries with supported key and value types

Avoid exposing Unity engine objects, services, delegates, file handles, or runtime-only references across the bridge. The state-only exceptions are Texture2D, Sprite, and RenderTexture; see Unity image sources. These image types are not supported in action parameters, action return values, or event payloads.

Naming

C# names are converted to camelCase in TypeScript:

public int CurrentHealth { get; set; }

bridge.currentHealth;

Use [BridgeName] only when you must preserve a different UI-facing name.

Enums

Enums appear in TypeScript as string values:

public enum Screen
{
    MainMenu,
    Hud
}

type Screen = 'MainMenu' | 'Hud';

Nulls

Prefer initialized values for state DTOs and collections. Nulls are harder for UI code to work with and can hide missing initialization during startup.

Regenerate after changes

Run:

Tools > Loom > Regenerate Types

after changing DTO fields, enum values, action signatures, or event payloads.