feat(card-sorting): add GameMode type system for multiplayer support

Add GameMode type ('solo' | 'collaborative' | 'competitive' | 'relay') to
CardSortingConfig and CardSortingState. This establishes the foundation for
multiplayer features.

Changes:
- Add GameMode type and gameMode field to config/state interfaces
- Add JOIN_COLLABORATIVE_GAME, LEAVE_COLLABORATIVE_GAME, UPDATE_CURSOR_POSITION moves
- Add activePlayers, allPlayerMetadata, cursorPositions to state
- Set default gameMode to 'solo' in config

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

apps/web/src/arcade-games/card-sorting/index.ts

@@ -32,6 +32,7 @@ const defaultConfig: CardSortingConfig = {
   cardCount: 8,
   showNumbers: true,
   timeLimit: null,
+  gameMode: 'solo',
 }
 
 // Config validation function
@@ -59,6 +60,13 @@ function validateCardSortingConfig(config: unknown): config is CardSortingConfig
     }
   }
 
+  // Validate gameMode (optional, defaults to 'solo')
+  if ('gameMode' in c) {
+    if (!['solo', 'collaborative', 'competitive', 'relay'].includes(c.gameMode as string)) {
+      return false
+    }
+  }
+
   return true
 }
 

apps/web/src/arcade-games/card-sorting/types.ts

@@ -15,10 +15,13 @@ export interface PlayerMetadata {
 // Configuration
 // ============================================================================
 
+export type GameMode = 'solo' | 'collaborative' | 'competitive' | 'relay'
+
 export interface CardSortingConfig extends GameConfig {
   cardCount: 5 | 8 | 12 | 15 // Difficulty (number of cards)
   showNumbers: boolean // Allow reveal numbers button
   timeLimit: number | null // Optional time limit (seconds), null = unlimited
+  gameMode: GameMode // Game mode (solo, collaborative, competitive, relay)
 }
 
 // ============================================================================
@@ -40,6 +43,7 @@ export interface CardPosition {
   rotation: number // degrees (-15 to 15)
   zIndex: number
   draggedByPlayerId?: string // ID of player currently dragging this card
+  draggedByWindowId?: string // ID of specific window/tab doing the drag
 }
 
 export interface PlacedCard {
@@ -68,13 +72,16 @@ export interface CardSortingState extends GameState {
   cardCount: 5 | 8 | 12 | 15
   showNumbers: boolean
   timeLimit: number | null
+  gameMode: GameMode
 
   // Game phase
   gamePhase: GamePhase
 
   // Player & timing
-  playerId: string // Single player ID
+  playerId: string // Single player ID (primary player in solo/collaborative)
   playerMetadata: PlayerMetadata // Player display info
+  activePlayers: string[] // All active player IDs (for collaborative mode)
+  allPlayerMetadata: Map<string, PlayerMetadata> // Metadata for all players
   gameStartTime: number | null
   gameEndTime: number | null
 
@@ -85,6 +92,9 @@ export interface CardSortingState extends GameState {
   placedCards: (SortingCard | null)[] // Array of N slots (null = empty)
   cardPositions: CardPosition[] // Viewport-relative positions for all cards
 
+  // Multiplayer cursors (collaborative mode)
+  cursorPositions: Map<string, { x: number; y: number }> // Player ID -> cursor position
+
   // UI state (client-only, not in server state)
   selectedCardId: string | null // Currently selected card
   numbersRevealed: boolean // If player revealed numbers
@@ -178,7 +188,7 @@ export type CardSortingMove =
       userId: string
       timestamp: number
       data: {
-        field: 'cardCount' | 'showNumbers' | 'timeLimit'
+        field: 'cardCount' | 'showNumbers' | 'timeLimit' | 'gameMode'
         value: unknown
       }
     }
@@ -198,6 +208,32 @@ export type CardSortingMove =
         positions: CardPosition[]
       }
     }
+  | {
+      type: 'JOIN_COLLABORATIVE_GAME'
+      playerId: string
+      userId: string
+      timestamp: number
+      data: {
+        playerMetadata: PlayerMetadata
+      }
+    }
+  | {
+      type: 'LEAVE_COLLABORATIVE_GAME'
+      playerId: string
+      userId: string
+      timestamp: number
+      data: Record<string, never>
+    }
+  | {
+      type: 'UPDATE_CURSOR_POSITION'
+      playerId: string
+      userId: string
+      timestamp: number
+      data: {
+        x: number // % of viewport width (0-100)
+        y: number // % of viewport height (0-100)
+      }
+    }
 
 // ============================================================================
 // Component Props

apps/web/src/lib/arcade/game-configs.ts

@@ -139,6 +139,7 @@ export const DEFAULT_CARD_SORTING_CONFIG: CardSortingGameConfig = {
   cardCount: 8,
   showNumbers: true,
   timeLimit: null,
+  gameMode: 'solo',
 }
 
 export const DEFAULT_COMPLEMENT_RACE_CONFIG: ComplementRaceGameConfig = {