Tabletopkit

# TabletopKit Extended Patterns

Overflow reference for the `tabletopkit` skill. Contains advanced patterns for
observer implementation, custom actions, dice physics, card layouts, network
coordination, and full game architecture examples.

## Contents

- [Observer Patterns](#observer-patterns)
- [Custom Action Patterns](#custom-action-patterns)
- [Dice Simulation](#dice-simulation)
- [Card and Tile Layouts](#card-and-tile-layouts)
- [Interaction Delegate Patterns](#interaction-delegate-patterns)
- [Full Game Architecture](#full-game-architecture)
- [Network and Multiplayer Coordination](#network-and-multiplayer-coordination)
- [State Bookmarks and Undo](#state-bookmarks-and-undo)
- [Score Tracking](#score-tracking)
- [Debugging Techniques](#debugging-techniques)

## Observer Patterns

### Implementing TabletopGame.Observer

The observer receives callbacks when actions are validated, pending, confirmed,
rolled back, or cancelled. Use `actionWasConfirmed` as the primary hook for
updating game-specific state.

```swift
import TabletopKit

class GameObserver: TabletopGame.Observer {
    weak var game: Game?

    func validateAction(_ action: some TabletopAction,
                        snapshot: TableSnapshot) -> Bool {
        // Return false to reject the action before it applies.
        // Called on the arbiter (host) device in multiplayer.
        if let moveAction = action as? MoveEquipmentAction {
            // Validate move is legal in current game rules
            return isLegalMove(moveAction, in: snapshot)
        }
        return true
    }

    func actionIsPending(_ action: some TabletopAction,
                         oldSnapshot: TableSnapshot,
                         newSnapshot: TableSnapshot) {
        // Action applied locally but not yet confirmed by arbiter.
        // Use for optimistic UI updates.
    }

    func actionWasConfirmed(_ action: some TabletopAction,
                            oldSnapshot: TableSnapshot,
                            newSnapshot: TableSnapshot) {
        guard let game else { return }

        // Handle built-in actions
        if let setTurn = action as? SetTurnAction {
            game.currentTurnSeats = setTurn.seatIDsInTurn
            return
        }

        if let counterAction = action as? UpdateCounterAction {
            game.scores[counterAction.counterID] = counterAction.newValue
            return
        }

        // Handle custom actions
        if let collect = CollectCoin(from: action) {
            handleCoinCollected(collect, snapshot: newSnapshot)
            return
        }
    }

    func actionWasRolledBack(_ action: some TabletopAction,
                             snapshot: TableSnapshot) {
        // Arbiter rejected the action. Revert optimistic UI.
    }

    func actionWasCancelled(_ action: some TabletopAction,
                            reason: TabletopGame.ActionCancellationReason) {
        switch reason {
        case .actionInvalidated:
            // Action was invalidated by a conflicting action
            break
        case .interactionCancelled:
            // The interaction that queued this action was cancelled
            break
        @unknown default:
            break
        }
    }

    func playerChangedSeats(_ player: Player,
                            oldSeat: (any TableSeat)?,
                            newSeat: (any TableSeat)?,
                            snapshot: TableSnapshot) {
        game?.updatePlayerList(snapshot: snapshot)
    }

    func stateDidResetToBookmark(_ bookmarkID: StateBookmarkIdentifier) {
        game?.handleStateReset()
    }

    private func isLegalMove(_ action: MoveEquipmentAction,
                             in snapshot: TableSnapshot) -> Bool {
        // Game-specific validation
        true
    }

    private func handleCoinCollected(_ action: CollectCoin,
                                     snapshot: TableSnapshot) {
        // Update game-specific state
    }
}
```

### Registering