Actions

Actions are public C# methods tagged [BridgeAction]. A public method without the attribute stays internal, only [BridgeAction] methods are exposed.

[BridgeAction]
public void StartGame()
{
    CurrentScreen = GameScreen.Hud;
}

await bridge.startGame();

Parameters

Actions can take any number of parameters:

[BridgeAction]
public void SetVolume(float value)
{
    Volume = value;
}

[BridgeAction]
public void MovePlayer(int x, int y, float speed)
{
    // ...
}

await bridge.setVolume(0.8);
await bridge.movePlayer(3, 4, 1.5);

You can also group related values in a DTO, handy when the set of fields evolves (new fields don’t change the call signature):

public sealed class BuyItemRequest
{
    public string Sku { get; set; } = "";
    public int Quantity { get; set; }
}

[BridgeAction]
public PurchaseResult BuyItem(BuyItemRequest request)
{
    // ...
}

Return values

Actions may return a value:

[BridgeAction]
public int GetCoins()
{
    return Coins;
}

The UI receives a promise:

const coins = await bridge.getCoins();

Async work

Use async actions when the game operation is asynchronous:

[BridgeAction]
public async Task<Profile> LoadProfile()
{
    return await ProfileService.LoadAsync();
}

Keep actions focused on user intent. Long-running work should update bridge state as it progresses so the UI can show loading or error states.

Nested actions

[BridgeAction] also goes on a method of a nested state DTO. The action surfaces at its dotted path on the bridge, mirroring the C# structure:

public sealed class BootState
{
    public float Progress { get; set; }

    [BridgeAction]
    public void SetProgress(float value) => Progress = value;
}

await bridge.boot.setProgress(0.5);

Errors

If an action throws, the UI promise rejects. Handle expected failures in the UI:

try {
  await bridge.buyItem({ sku, quantity: 1 });
} catch (error) {
  setError(String(error));
}