chore(release): 2.12.2 [skip ci]

## [2.12.2](https://github.com/antialias/soroban-abacus-flashcards/compare/v2.12.1...v2.12.2) (2025-10-09)

### Bug Fixes

* use RoomMemoryPairsProvider in room page ([c279731](c27973191f))

CHANGELOG.md

@@ -1,3 +1,24 @@
+## [2.12.2](https://github.com/antialias/soroban-abacus-flashcards/compare/v2.12.1...v2.12.2) (2025-10-09)
+
+
+### Bug Fixes
+
+* use RoomMemoryPairsProvider in room page ([c279731](https://github.com/antialias/soroban-abacus-flashcards/commit/c27973191f0144604e17a8a14adf0a88df476e27))
+
+## [2.12.1](https://github.com/antialias/soroban-abacus-flashcards/compare/v2.12.0...v2.12.1) (2025-10-09)
+
+
+### Bug Fixes
+
+* export MemoryPairsContext to fix provider hook error ([80ad33e](https://github.com/antialias/soroban-abacus-flashcards/commit/80ad33eec0b6946702eaa9cf1b1c246852864b00))
+
+## [2.12.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v2.11.0...v2.12.0) (2025-10-09)
+
+
+### Features
+
+* add networked hover state infrastructure for multiplayer presence ([d149799](https://github.com/antialias/soroban-abacus-flashcards/commit/d14979907c5df9b793a1c110028fc5b54457f507))
+
 ## [2.11.0](https://github.com/antialias/soroban-abacus-flashcards/compare/v2.10.1...v2.11.0) (2025-10-09)
 
 

apps/web/.claude/ARCADE_ARCHITECTURE.md

@@ -0,0 +1,492 @@
+# Arcade Game Architecture
+
+## Overview
+
+The arcade system supports two distinct game modes that must remain completely isolated from each other:
+
+1. **Local Play** - Games without network synchronization (can be single-player OR local multiplayer)
+2. **Room-Based Play** - Networked games with real-time synchronization across room members
+
+## Core Terminology
+
+Following `docs/terminology-user-player-room.md`:
+
+- **USER** - Identity (guest or authenticated account), retrieved via `useViewerId()`, one per browser/account
+- **PLAYER** - Game avatar/profile (e.g., "Alice 👧", "Bob 👦"), stored in `players` table
+- **PLAYER ROSTER** - All PLAYERS belonging to a USER (can have many)
+- **ACTIVE PLAYERS** - PLAYERS where `isActive = true` - these are the ones that actually participate in games
+- **ROOM MEMBER** - A USER's participation in a multiplayer room (tracked in `room_members` table)
+
+**Important:** A USER can have many PLAYERS in their roster, but only the ACTIVE PLAYERS (where `isActive = true`) participate in games. This enables "hot-potato" style local multiplayer where multiple people share the same device. This is LOCAL play (not networked), even though multiple PLAYERS participate.
+
+In arcade sessions:
+- `arcade_sessions.userId` - The USER who owns the session
+- `arcade_sessions.activePlayers` - Array of PLAYER IDs (only active players with `isActive = true`)
+- `arcade_sessions.roomId` - If present, the room ID for networked play (references `arcade_rooms.id`)
+
+## Critical Architectural Requirements
+
+### 1. Mode Isolation (MUST ENFORCE)
+
+**Local Play** (`/arcade/[game-name]`)
+- MUST NOT sync game state across the network
+- MUST NOT use room data, even if the USER is currently a member of an active room
+- MUST create isolated, per-USER game sessions
+- Game state lives only in the current browser tab/session
+- CAN have multiple ACTIVE PLAYERS from the same USER (local multiplayer / hot-potato)
+- State is NOT shared across the network, only within the browser session
+
+**Room-Based Play** (`/arcade/room`)
+- MUST sync game state across all room members via network
+- MUST use the USER's current active room
+- MUST coordinate moves via server WebSocket
+- Game state is shared across all ACTIVE PLAYERS from all USERS in the room
+- When a PLAYER makes a move, all room members see it in real-time
+- CAN ALSO have multiple ACTIVE PLAYERS per USER (networked + local multiplayer combined)
+
+### 2. Room ID Usage Rules
+
+```typescript
+// ❌ WRONG: Always checking for room data
+const { roomData } = useRoomData()
+useArcadeSession({ roomId: roomData?.id })  // This causes the bug!
+
+// ✅ CORRECT: Explicit mode control via separate providers
+<LocalMemoryPairsProvider>     {/* Never passes roomId */}
+<RoomMemoryPairsProvider>       {/* Always passes roomId */}
+```
+
+**Key principle:** The presence of a `roomId` parameter in `useArcadeSession` determines synchronization behavior:
+- `roomId` present → room-wide network sync enabled (room-based play)
+- `roomId` undefined → local play only (no network sync)
+
+### 3. Composition Over Flags (PREFERRED APPROACH)
+
+**✅ Option 1: Separate Providers (CLEAREST - USE THIS)**
+
+Create two distinct provider components:
+
+```typescript
+// context/LocalMemoryPairsProvider.tsx
+export function LocalMemoryPairsProvider({ children }) {
+  const { data: viewerId } = useViewerId()
+  const { activePlayers } = useGameMode()  // Gets active players (isActive = true)
+  // NEVER fetch room data for local play
+
+  const { state, sendMove } = useArcadeSession<MemoryPairsState>({
+    userId: viewerId || '',
+    roomId: undefined,  // Explicitly undefined - no network sync
+    initialState,
+    applyMove: applyMoveOptimistically,
+  })
+
+  // ... rest of provider logic
+  // Note: activePlayers contains only PLAYERS with isActive = true
+}
+
+// context/RoomMemoryPairsProvider.tsx
+export function RoomMemoryPairsProvider({ children }) {
+  const { data: viewerId } = useViewerId()
+  const { roomData } = useRoomData()  // OK to fetch for room-based play
+  const { activePlayers } = useGameMode()  // Gets active players (isActive = true)
+
+  const { state, sendMove } = useArcadeSession<MemoryPairsState>({
+    userId: viewerId || '',
+    roomId: roomData?.id,  // Pass roomId for network sync
+    initialState,
+    applyMove: applyMoveOptimistically,
+  })
+
+  // ... rest of provider logic
+}
+```
+
+Then use them explicitly:
+```typescript
+// /arcade/matching/page.tsx (Local Play)
+export default function MatchingPage() {
+  return (
+    <ArcadeGuardedPage>
+      <LocalMemoryPairsProvider>
+        <MemoryPairsGame />
+      </LocalMemoryPairsProvider>
+    </ArcadeGuardedPage>
+  )
+}
+
+// /arcade/room/page.tsx (Room-Based Play)
+export default function RoomPage() {
+  // ... room validation logic
+  if (roomData.gameName === 'matching') {
+    return (
+      <RoomMemoryPairsProvider>
+        <MemoryPairsGame />
+      </RoomMemoryPairsProvider>
+    )
+  }
+}
+```
+
+**Benefits of separate providers:**
+- Compile-time safety - impossible to mix modes
+- Clear intent - any developer can see which mode at a glance
+- No runtime conditionals needed
+- Easier to test - each provider tests separately
+
+**❌ Avoid:** Runtime flag checking scattered throughout code
+```typescript
+// Anti-pattern: Too many conditionals
+if (isRoomBased) { ... } else { ... }
+```
+
+### 4. How Synchronization Works
+
+#### Local Play Flow
+```
+USER Action → useArcadeSession (roomId: undefined)
+           → WebSocket emit('join-arcade-session', { userId })
+           → Server creates isolated session for userId
+           → Session key = userId
+           → session.activePlayers = USER's active player IDs (isActive = true)
+           → State changes only affect this USER's browser tabs
+
+Note: Multiple ACTIVE PLAYERS from same USER can participate (local multiplayer),
+      but state is NEVER synced across network
+```
+
+#### Room-Based Play Flow
+```
+USER Action (on behalf of PLAYER)
+         → useArcadeSession (roomId: 'room_xyz')
+         → WebSocket emit('join-arcade-session', { userId, roomId })
+         → Server creates/joins shared session for roomId
+         → session.activePlayers = ALL active players from ALL room members
+         → Socket joins TWO rooms: `arcade:${userId}` AND `game:${roomId}`
+         → PLAYER makes move
+         → Server validates PLAYER ownership (is this PLAYER owned by this USER?)
+         → State changes broadcast to:
+            - arcade:${userId} - All tabs of this USER (for optimistic reconciliation)
+            - game:${roomId} - All USERS in the room (for network sync)
+
+Note: Each USER can still have multiple ACTIVE PLAYERS (local + networked multiplayer)
+```
+
+The server-side logic uses `roomId` to determine session scope:
+- No `roomId`: Session key = `userId` (isolated to USER's browser)
+- With `roomId`: Session key = `roomId` (shared across all room members)
+
+See `docs/MULTIPLAYER_SYNC_ARCHITECTURE.md` for detailed socket room mechanics.
+
+### 5. USER vs PLAYER in Game Logic
+
+**Important distinction:**
+- **Session ownership**: Tracked by USER ID (`useViewerId()`)
+- **Player roster**: All PLAYERS for a USER (can be many)
+- **Active players**: PLAYERS with `isActive = true` (these join the game)
+- **Game actions**: Performed by PLAYER ID (from `players` table)
+- **Move validation**: Server checks that PLAYER ID belongs to the requesting USER
+- **Local multiplayer**: One USER with multiple ACTIVE PLAYERS (hot-potato style, same device)
+- **Networked multiplayer**: Multiple USERS, each with their own ACTIVE PLAYERS, in a room
+
+```typescript
+// ✅ Correct: USER owns session, ACTIVE PLAYERS participate
+const { data: viewerId } = useViewerId()  // USER ID
+const { activePlayers } = useGameMode()   // ACTIVE PLAYER IDs (isActive = true)
+
+// activePlayers might be [player_001, player_002]
+// even though USER has 5 total PLAYERS in their roster
+
+const { state, sendMove } = useArcadeSession({
+  userId: viewerId,  // Session owned by USER
+  roomId: undefined, // Local play (or roomData?.id for room-based)
+  // ...
+})
+
+// When PLAYER flips card:
+sendMove({
+  type: 'FLIP_CARD',
+  playerId: currentPlayerId,  // PLAYER ID from activePlayers
+  data: { cardId: '...' }
+})
+```
+
+**Example Scenarios:**
+
+1. **Single-player local game:**
+   - USER: "guest_abc"
+   - Player roster: ["player_001" (active), "player_002" (inactive), "player_003" (inactive)]
+   - Active PLAYERS in game: ["player_001"]
+   - Mode: Local play (no roomId)
+
+2. **Local multiplayer (hot-potato):**
+   - USER: "guest_abc"
+   - Player roster: ["player_001" (active), "player_002" (active), "player_003" (active), "player_004" (inactive)]
+   - Active PLAYERS in game: ["player_001", "player_002", "player_003"] (3 kids sharing device)
+   - Mode: Local play (no roomId)
+   - Game rotates turns between the 3 active PLAYERS, but NO network sync
+
+3. **Room-based networked play:**
+   - USER A: "guest_abc"
+     - Player roster: 5 total PLAYERS
+     - Active PLAYERS: ["player_001", "player_002"]
+   - USER B: "guest_def"
+     - Player roster: 3 total PLAYERS
+     - Active PLAYERS: ["player_003"]
+   - Mode: Room-based play (roomId: "room_xyz")
+   - Total PLAYERS in game: 3 (player_001, player_002, player_003)
+   - All 3 synced across network
+
+4. **Room-based + local multiplayer combined:**
+   - USER A: "guest_abc" with 3 active PLAYERS (3 kids at Device A)
+   - USER B: "guest_def" with 2 active PLAYERS (2 kids at Device B)
+   - Mode: Room-based play (roomId: "room_xyz")
+   - 5 total active PLAYERS across 2 devices, all synced over network
+
+## Common Mistakes to Avoid
+
+### Mistake 1: Conditional Room Usage
+```typescript
+// ❌ BAD: Room sync leaks into local play
+const { roomData } = useRoomData()
+useArcadeSession({
+  roomId: roomData?.id  // Local play will sync if USER is in a room!
+})
+```
+
+### Mistake 2: Shared Components Without Mode Context
+```typescript
+// ❌ BAD: Same provider used for both modes
+export default function LocalGamePage() {
+  return <GameProvider><Game /></GameProvider>  // Which mode?
+}
+```
+
+### Mistake 3: Confusing "multiplayer" with "networked"
+```typescript
+// ❌ BAD: Thinking multiple PLAYERS means room-based
+if (activePlayers.length > 1) {
+  // Must be room-based!  WRONG!
+  // Could be local multiplayer (hot-potato style)
+}
+
+// ✅ CORRECT: Check for roomId to determine network sync
+const isNetworked = !!roomId
+const isLocalMultiplayer = activePlayers.length > 1 && !roomId
+```
+
+### Mistake 4: Using all PLAYERS instead of only active ones
+```typescript
+// ❌ BAD: Including inactive players
+const allPlayers = await db.query.players.findMany({
+  where: eq(players.userId, userId)
+})
+
+// ✅ CORRECT: Only active players join the game
+const activePlayers = await db.query.players.findMany({
+  where: and(
+    eq(players.userId, userId),
+    eq(players.isActive, true)
+  )
+})
+```
+
+### Mistake 5: Mixing USER ID and PLAYER ID
+```typescript
+// ❌ BAD: Using USER ID for game actions
+sendMove({
+  type: 'FLIP_CARD',
+  playerId: viewerId,  // WRONG! viewerId is USER ID, not PLAYER ID
+  data: { cardId: '...' }
+})
+
+// ✅ CORRECT: Use PLAYER ID from game state
+sendMove({
+  type: 'FLIP_CARD',
+  playerId: state.currentPlayer,  // PLAYER ID from activePlayers
+  data: { cardId: '...' }
+})
+```
+
+### Mistake 6: Server-Side Ambiguity
+```typescript
+// ❌ BAD: Server can't distinguish intent
+socket.on('join-arcade-session', ({ userId, roomId }) => {
+  // If roomId exists, did USER want local or room-based play?
+  // This happens when provider always passes roomData?.id
+})
+```
+
+## Testing Requirements
+
+Tests MUST verify mode isolation:
+
+### Local Play Tests
+```typescript
+it('should NOT sync state when USER is in a room but playing locally', async () => {
+  // Setup: USER is a member of an active room
+  // Action: USER navigates to /arcade/matching
+  // Assert: Game state is NOT shared with other room members
+  // Assert: Other room members' actions do NOT affect this game
+})
+
+it('should create isolated sessions for concurrent local games', () => {
+  // Setup: Two USERS who are members of the same room
+  // Action: Both navigate to /arcade/matching separately
+  // Assert: Each has independent game state
+  // Assert: USER A's moves do NOT appear in USER B's game
+})
+
+it('should support local multiplayer without network sync', () => {
+  // Setup: USER with 3 active PLAYERS in roster (hot-potato style)
+  // Action: USER plays at /arcade/matching with the 3 active PLAYERS
+  // Assert: All 3 active PLAYERS participate in the same session
+  // Assert: Inactive PLAYERS do NOT participate
+  // Assert: State is NOT synced across network
+  // Assert: Game rotates turns between active PLAYERS locally
+})
+
+it('should only include active players in game', () => {
+  // Setup: USER has 5 PLAYERS in roster, but only 2 are active
+  // Action: USER starts a local game
+  // Assert: Only the 2 active PLAYERS are in activePlayers array
+  // Assert: Inactive PLAYERS are not included
+})
+
+it('should sync across USER tabs but not across network', () => {
+  // Setup: USER opens /arcade/matching in 2 browser tabs
+  // Action: PLAYER makes move in Tab 1
+  // Assert: Tab 2 sees the move (multi-tab sync)
+  // Assert: Other USERS do NOT see the move (no network sync)
+})
+```
+
+### Room-Based Play Tests
+```typescript
+it('should sync state across all room members', async () => {
+  // Setup: Two USERS are members of the same room
+  // Action: USER A's PLAYER flips card at /arcade/room
+  // Assert: USER B sees the card flip in real-time
+})
+
+it('should sync across multiple active PLAYERS from multiple USERS', () => {
+  // Setup: USER A has 2 active PLAYERS, USER B has 1 active PLAYER in same room
+  // Action: USER A's PLAYER 1 makes move
+  // Assert: All 3 PLAYERS see the move (networked)
+})
+
+it('should only include active players in room games', () => {
+  // Setup: USER A (5 PLAYERS, 2 active), USER B (3 PLAYERS, 1 active) join room
+  // Action: Game starts
+  // Assert: session.activePlayers = [userA_player1, userA_player2, userB_player1]
+  // Assert: Inactive PLAYERS are NOT included
+})
+
+it('should handle combined local + networked multiplayer', () => {
+  // Setup: USER A (3 active PLAYERS), USER B (2 active PLAYERS) in same room
+  // Action: Any PLAYER makes a move
+  // Assert: All 5 active PLAYERS see the move across both devices
+})
+
+it('should fail gracefully when no room exists', () => {
+  // Setup: USER is not a member of any room
+  // Action: Navigate to /arcade/room
+  // Assert: Shows "No active room" message
+  // Assert: Does not create a session
+})
+
+it('should validate PLAYER ownership', async () => {
+  // Setup: USER A in room with active PLAYER 'alice'
+  // Action: USER A attempts move for PLAYER 'bob' (owned by USER B)
+  // Assert: Server rejects the move
+  // Assert: Error indicates unauthorized PLAYER
+})
+```
+
+## Implementation Checklist
+
+When adding a new game or modifying existing ones:
+
+- [ ] Create separate `LocalGameProvider` and `RoomGameProvider` components
+- [ ] Local provider never calls `useRoomData()`
+- [ ] Local provider passes `roomId: undefined` to `useArcadeSession`
+- [ ] Room provider calls `useRoomData()` and passes `roomId: roomData?.id`
+- [ ] Both providers use `useGameMode()` to get active players
+- [ ] Local play page uses `LocalGameProvider`
+- [ ] `/arcade/room` page uses `RoomGameProvider`
+- [ ] Game components correctly use PLAYER IDs (not USER IDs) for moves
+- [ ] Game supports multiple active PLAYERS from same USER (local multiplayer)
+- [ ] Inactive PLAYERS are never included in game sessions
+- [ ] Tests verify mode isolation (local doesn't network sync, room-based does)
+- [ ] Tests verify PLAYER ownership validation
+- [ ] Tests verify only active PLAYERS participate
+- [ ] Tests verify local multiplayer works (multiple active PLAYERS, one USER)
+- [ ] Documentation updated if behavior changes
+
+## File Organization
+
+```
+src/app/arcade/
+├── [game-name]/                    # Local play games
+│   ├── page.tsx                   # Uses LocalGameProvider
+│   └── context/
+│       ├── LocalGameProvider.tsx  # roomId: undefined
+│       └── RoomGameProvider.tsx   # roomId: roomData?.id
+├── room/                           # Room-based play
+│   └── page.tsx                   # Uses RoomGameProvider
+└── ...
+```
+
+## Architecture Decision Records
+
+### Why separate providers instead of auto-detect from route?
+
+While we could detect mode based on the route (`/arcade/room` vs `/arcade/matching`), separate providers are clearer and prevent accidental misuse. Future developers can immediately see the intent, and the type system can enforce correctness.
+
+### Why being in a room doesn't mean all games sync?
+
+A USER being a room member does NOT mean all their games should network sync. They should be able to play local games while remaining in a room for future room-based sessions. Mode is determined by the page they're on, not their room membership status.
+
+### Why not use a single shared provider with mode props?
+
+We tried that. It led to the current bug where local play accidentally synced with rooms. Separate providers make the distinction compile-time safe rather than runtime conditional, and eliminate the possibility of accidentally passing `roomId` when we shouldn't.
+
+### Why do we track sessions by USER but moves by PLAYER?
+
+- **Sessions** are per-USER because each USER can have their own game session
+- **Moves** are per-PLAYER because PLAYERS are the game avatars that score points
+- **Only active PLAYERS** (isActive = true) participate in games
+- This allows:
+  - One USER with multiple active PLAYERS (local multiplayer / hot-potato)
+  - Multiple USERS in one room (networked play)
+  - Combined: Multiple USERS each with multiple active PLAYERS (local + networked)
+  - Proper ownership validation (server checks USER owns PLAYER)
+  - PLAYERS can be toggled active/inactive without deleting them
+
+### Why use "local" vs "room-based" instead of "solo" vs "multiplayer"?
+
+- **"Solo"** is misleading - a USER can have multiple active PLAYERS in local play (hot-potato style)
+- **"Multiplayer"** is ambiguous - it could mean local multiplayer OR networked multiplayer
+- **"Local play"** clearly means: no network sync (but can have multiple active PLAYERS)
+- **"Room-based play"** clearly means: network sync across room members
+
+## Related Files
+
+- `src/hooks/useArcadeSession.ts` - Session management with optional roomId
+- `src/hooks/useArcadeSocket.ts` - WebSocket connection with sync logic (socket rooms: `arcade:${userId}` and `game:${roomId}`)
+- `src/hooks/useRoomData.ts` - Fetches USER's current room membership
+- `src/hooks/useViewerId.ts` - Retrieves current USER ID
+- `src/contexts/GameModeContext.tsx` - Provides active PLAYER information
+- `src/app/arcade/matching/context/ArcadeMemoryPairsContext.tsx` - Game context (needs refactoring to separate providers)
+- `src/app/arcade/matching/page.tsx` - Local play entry point
+- `src/app/arcade/room/page.tsx` - Room-based play entry point
+- `docs/terminology-user-player-room.md` - Terminology guide (USER/PLAYER/MEMBER)
+- `docs/MULTIPLAYER_SYNC_ARCHITECTURE.md` - Technical details of room-based sync
+
+## Version History
+
+- **2025-10-09**: Initial documentation
+  - Issue identified: Local play was syncing with rooms over network
+  - Root cause: Same provider always fetched `roomData` and passed `roomId` to `useArcadeSession`
+  - Solution: Separate providers for local vs room-based play
+  - Terminology clarification: "local" vs "room-based" (not "solo" vs "multiplayer")
+  - Active players: Only PLAYERS with `isActive = true` participate in games

apps/web/.claude/ARCADE_SETUP_PATTERN.md

@@ -0,0 +1,416 @@
+# Arcade Setup Pattern
+
+## Overview
+
+This document describes the **standard synchronized setup pattern** for arcade games. Following this pattern ensures that:
+
+1. ✅ **Setup is synchronized** - All room members see the same setup screen and config changes in real-time
+2. ✅ **No local state hacks** - Configuration lives entirely in session state, no React state merging
+3. ✅ **Optimistic updates** - Config changes feel instant with client-side prediction
+4. ✅ **Consistent pattern** - All games follow the same architecture
+
+**Reference Implementation**: `src/app/arcade/matching/*` (Matching game)
+
+---
+
+## Core Concept
+
+Setup configuration is **game state**, not UI state. Configuration changes are **moves** that are validated, synchronized, and can be made by any room member.
+
+### Key Principles
+
+1. **Game state includes configuration** during ALL phases (setup, playing, results)
+2. **No local React state** for configuration - use session state directly
+3. **Standard move types** that all games should implement
+4. **Setup phase is collaborative** - any room member can configure the game
+
+---
+
+## Required Move Types
+
+Every arcade game must support these standard moves:
+
+### 1. `GO_TO_SETUP`
+
+Transitions game to setup phase, allowing reconfiguration.
+
+```typescript
+{
+  type: 'GO_TO_SETUP',
+  playerId: string,
+  data: {}
+}
+```
+
+**Behavior:**
+- Can be called from any phase (setup, playing, results)
+- Sets `gamePhase: 'setup'`
+- Resets game progression (scores, cards, etc.)
+- Preserves configuration (players can modify it)
+- Synchronized across all room members
+
+### 2. `SET_CONFIG`
+
+Updates a configuration field during setup phase.
+
+```typescript
+{
+  type: 'SET_CONFIG',
+  playerId: string,
+  data: {
+    field: string,  // Config field name
+    value: any      // New value
+  }
+}
+```
+
+**Behavior:**
+- Only allowed during setup phase
+- Validates field name and value
+- Updates immediately with optimistic update
+- Synchronized across all room members
+
+### 3. `START_GAME`
+
+Starts the game with current configuration.
+
+```typescript
+{
+  type: 'START_GAME',
+  playerId: string,
+  data: {
+    activePlayers: string[],
+    playerMetadata: { [playerId: string]: PlayerMetadata },
+    // ... game-specific initial data
+  }
+}
+```
+
+**Behavior:**
+- Only allowed during setup phase
+- Uses current session state configuration
+- Initializes game-specific state
+- Sets `gamePhase: 'playing'`
+
+---
+
+## Implementation Checklist
+
+### 1. Update Validation Types
+
+Add move types to your game's validation types:
+
+```typescript
+// src/lib/arcade/validation/types.ts
+
+export interface YourGameGoToSetupMove extends GameMove {
+  type: 'GO_TO_SETUP'
+  data: Record<string, never>
+}
+
+export interface YourGameSetConfigMove extends GameMove {
+  type: 'SET_CONFIG'
+  data: {
+    field: 'configField1' | 'configField2' | 'configField3'
+    value: any
+  }
+}
+
+export type YourGameMove =
+  | YourGameStartGameMove
+  | YourGameGoToSetupMove
+  | YourGameSetConfigMove
+  | ... // other game-specific moves
+```
+
+### 2. Implement Validators
+
+Add validators for setup moves in your game's validator class:
+
+```typescript
+// src/lib/arcade/validation/YourGameValidator.ts
+
+export class YourGameValidator implements GameValidator<YourGameState, YourGameMove> {
+  validateMove(state, move, context) {
+    switch (move.type) {
+      case 'GO_TO_SETUP':
+        return this.validateGoToSetup(state)
+
+      case 'SET_CONFIG':
+        return this.validateSetConfig(state, move.data.field, move.data.value)
+
+      case 'START_GAME':
+        return this.validateStartGame(state, move.data)
+
+      // ... other moves
+    }
+  }
+
+  private validateGoToSetup(state: YourGameState): ValidationResult {
+    return {
+      valid: true,
+      newState: {
+        ...state,
+        gamePhase: 'setup',
+        // Reset game progression, preserve configuration
+        // ... reset scores, game data, etc.
+      },
+    }
+  }
+
+  private validateSetConfig(
+    state: YourGameState,
+    field: string,
+    value: any
+  ): ValidationResult {
+    // Only during setup
+    if (state.gamePhase !== 'setup') {
+      return { valid: false, error: 'Cannot change config outside setup' }
+    }
+
+    // Validate field-specific values
+    switch (field) {
+      case 'configField1':
+        if (!isValidValue(value)) {
+          return { valid: false, error: 'Invalid value' }
+        }
+        break
+      // ... validate other fields
+    }
+
+    return {
+      valid: true,
+      newState: { ...state, [field]: value },
+    }
+  }
+
+  private validateStartGame(state: YourGameState, data: any): ValidationResult {
+    if (state.gamePhase !== 'setup') {
+      return { valid: false, error: 'Can only start from setup' }
+    }
+
+    // Use current state configuration to initialize game
+    const initialGameData = initializeYourGame(state.configField1, state.configField2)
+
+    return {
+      valid: true,
+      newState: {
+        ...state,
+        gamePhase: 'playing',
+        ...initialGameData,
+      },
+    }
+  }
+}
+```
+
+### 3. Add Optimistic Updates
+
+Update `applyMoveOptimistically` in your providers:
+
+```typescript
+// src/app/arcade/your-game/context/YourGameProvider.tsx
+
+function applyMoveOptimistically(state: YourGameState, move: GameMove): YourGameState {
+  switch (move.type) {
+    case 'GO_TO_SETUP':
+      return {
+        ...state,
+        gamePhase: 'setup',
+        // Reset game state, preserve config
+      }
+
+    case 'SET_CONFIG':
+      const { field, value } = move.data
+      return {
+        ...state,
+        [field]: value,
+      }
+
+    case 'START_GAME':
+      return {
+        ...state,
+        gamePhase: 'playing',
+        // ... initialize game data from move
+      }
+
+    // ... other moves
+  }
+}
+```
+
+### 4. Remove Local State from Providers
+
+**❌ OLD PATTERN (Don't do this):**
+
+```typescript
+// DON'T: Local React state for configuration
+const [localDifficulty, setLocalDifficulty] = useState(6)
+
+// DON'T: Merge hack
+const effectiveState = state.gamePhase === 'setup'
+  ? { ...state, difficulty: localDifficulty }
+  : state
+
+// DON'T: Direct setter
+const setDifficulty = (value) => setLocalDifficulty(value)
+```
+
+**✅ NEW PATTERN (Do this):**
+
+```typescript
+// DO: Use session state directly
+const { state, sendMove } = useArcadeSession(...)
+
+// DO: Send move for config changes
+const setDifficulty = useCallback((value) => {
+  const playerId = activePlayers[0] || ''
+  sendMove({
+    type: 'SET_CONFIG',
+    playerId,
+    data: { field: 'difficulty', value },
+  })
+}, [activePlayers, sendMove])
+
+// DO: Use state directly (no merging!)
+const contextValue = { state: { ...state, gameMode }, ... }
+```
+
+### 5. Update Action Creators
+
+All configuration actions should send moves:
+
+```typescript
+export function YourGameProvider({ children }) {
+  const { state, sendMove } = useArcadeSession(...)
+
+  const setConfigField = useCallback((value) => {
+    const playerId = activePlayers[0] || ''
+    sendMove({
+      type: 'SET_CONFIG',
+      playerId,
+      data: { field: 'configField', value },
+    })
+  }, [activePlayers, sendMove])
+
+  const goToSetup = useCallback(() => {
+    const playerId = activePlayers[0] || state.currentPlayer || ''
+    sendMove({
+      type: 'GO_TO_SETUP',
+      playerId,
+      data: {},
+    })
+  }, [activePlayers, state.currentPlayer, sendMove])
+
+  const startGame = useCallback(() => {
+    // Use current session state config (not local state!)
+    const initialData = initializeGame(state.config1, state.config2)
+
+    const playerId = activePlayers[0]
+    sendMove({
+      type: 'START_GAME',
+      playerId,
+      data: {
+        ...initialData,
+        activePlayers,
+        playerMetadata: capturePlayerMetadata(players, activePlayers),
+      },
+    })
+  }, [state.config1, state.config2, activePlayers, sendMove])
+
+  return <YourGameContext.Provider value={...} />
+}
+```
+
+---
+
+## Benefits of This Pattern
+
+### 1. **Synchronized Setup**
+- User A clicks "Setup" → All room members see setup screen
+- User B changes difficulty → All room members see the change
+- User A clicks "Start" → All room members start playing
+
+### 2. **No Special Cases**
+- Setup works like gameplay (moves + validation)
+- No conditional logic based on phase
+- No React state merging hacks
+
+### 3. **Easy to Extend**
+- New games copy the same pattern
+- Well-documented and tested
+- Consistent developer experience
+
+### 4. **Optimistic Updates**
+- Config changes feel instant
+- Client-side prediction + server validation
+- Rollback on validation failure
+
+---
+
+## Testing Checklist
+
+When implementing this pattern, test these scenarios:
+
+### Local Mode
+- [ ] Click setup button during game → returns to setup
+- [ ] Change config fields → updates immediately
+- [ ] Start game → uses current config
+
+### Room Mode (Multi-User)
+- [ ] User A clicks setup → User B sees setup screen
+- [ ] User A changes difficulty → User B sees change in real-time
+- [ ] User B changes game type → User A sees change in real-time
+- [ ] User A starts game → Both users see game with same config
+
+### Edge Cases
+- [ ] Change config rapidly → no race conditions
+- [ ] User with 0 players can see/modify setup
+- [ ] Setup → Play → Setup preserves last config
+- [ ] Invalid config values are rejected by validator
+
+---
+
+## Migration Guide
+
+If you have an existing game using local state, follow these steps:
+
+### Step 1: Add Move Types
+Add `GO_TO_SETUP` and `SET_CONFIG` to your validation types.
+
+### Step 2: Implement Validators
+Add validators for the new moves in your game validator class.
+
+### Step 3: Add Optimistic Updates
+Update `applyMoveOptimistically` to handle the new moves.
+
+### Step 4: Remove Local State
+1. Delete all `useState` calls for configuration
+2. Delete the `effectiveState` merging logic
+3. Update action creators to send moves instead
+
+### Step 5: Test
+Run through the testing checklist above.
+
+---
+
+## Reference Implementation
+
+See the Matching game for a complete reference implementation:
+
+- **Types**: `src/lib/arcade/validation/types.ts`
+- **Validator**: `src/lib/arcade/validation/MatchingGameValidator.ts`
+- **Provider**: `src/app/arcade/matching/context/RoomMemoryPairsProvider.tsx`
+- **Optimistic Updates**: `applyMoveOptimistically` function in provider
+
+Look for comments marked with:
+- `// STANDARD ARCADE PATTERN: GO_TO_SETUP`
+- `// STANDARD ARCADE PATTERN: SET_CONFIG`
+- `// NO LOCAL STATE`
+- `// NO MORE effectiveState merging!`
+
+---
+
+## Questions?
+
+If something is unclear or you encounter issues implementing this pattern, refer to the Matching game implementation or update this document with clarifications.

apps/web/.claude/settings.local.json

@@ -1,6 +1,16 @@
 {
   "permissions": {
-    "allow": ["Bash(npm test:*)", "Read(//Users/antialias/projects/**)"],
+    "allow": [
+      "Bash(npm test:*)",
+      "Read(//Users/antialias/projects/**)",
+      "Bash(npm run lint:*)",
+      "Bash(git add:*)",
+      "Bash(git commit:*)",
+      "Bash(git push:*)",
+      "Bash(git pull:*)",
+      "Bash(git stash:*)",
+      "Bash(npm run format:*)"
+    ],
     "deny": [],
     "ask": []
   }

apps/web/src/app/arcade/matching/components/GamePhase.tsx

@@ -3,12 +3,12 @@
 import { css } from '../../../../../styled-system/css'
 import { useGameMode } from '../../../../contexts/GameModeContext'
 import { pluralizeWord } from '../../../../utils/pluralization'
-import { useArcadeMemoryPairs } from '../context/ArcadeMemoryPairsContext'
+import { useMemoryPairs } from '../context/MemoryPairsContext'
 import { MemoryGrid } from './MemoryGrid'
 import { PlayerStatusBar } from './PlayerStatusBar'
 
 export function GamePhase() {
-  const { state, resetGame: _resetGame, activePlayers } = useArcadeMemoryPairs()
+  const { state, resetGame: _resetGame, activePlayers } = useMemoryPairs()
   const { players: playerMap, activePlayers: activePlayerIds } = useGameMode()
 
   // Convert Map to array and create mapping from numeric index to player

apps/web/src/app/arcade/matching/components/MemoryGrid.tsx

@@ -2,7 +2,7 @@
 
 import { useEffect, useMemo, useState } from 'react'
 import { css } from '../../../../../styled-system/css'
-import { useArcadeMemoryPairs } from '../context/ArcadeMemoryPairsContext'
+import { useMemoryPairs } from '../context/MemoryPairsContext'
 import { getGridConfiguration } from '../utils/cardGeneration'
 import { GameCard } from './GameCard'
 
@@ -81,7 +81,7 @@ function useGridDimensions(gridConfig: any, totalCards: number) {
 }
 
 export function MemoryGrid() {
-  const { state, flipCard } = useArcadeMemoryPairs()
+  const { state, flipCard } = useMemoryPairs()
 
   // Hooks must be called before early return
   const gridConfig = useMemo(() => getGridConfiguration(state.difficulty), [state.difficulty])

apps/web/src/app/arcade/matching/components/MemoryPairsGame.tsx

@@ -7,14 +7,14 @@ import { useArcadeRedirect } from '@/hooks/useArcadeRedirect'
 import { css } from '../../../../../styled-system/css'
 import { StandardGameLayout } from '../../../../components/StandardGameLayout'
 import { useFullscreen } from '../../../../contexts/FullscreenContext'
-import { useArcadeMemoryPairs } from '../context/ArcadeMemoryPairsContext'
+import { useMemoryPairs } from '../context/MemoryPairsContext'
 import { GamePhase } from './GamePhase'
 import { ResultsPhase } from './ResultsPhase'
 import { SetupPhase } from './SetupPhase'
 
 export function MemoryPairsGame() {
   const router = useRouter()
-  const { state, exitSession, resetGame } = useArcadeMemoryPairs()
+  const { state, exitSession, resetGame } = useMemoryPairs()
   const { setFullscreenElement } = useFullscreen()
   const { canModifyPlayers } = useArcadeRedirect({ currentGame: 'matching' })
   const gameRef = useRef<HTMLDivElement>(null)

apps/web/src/app/arcade/matching/components/PlayerStatusBar.tsx

@@ -3,7 +3,7 @@
 import { css } from '../../../../../styled-system/css'
 import { useGameMode } from '../../../../contexts/GameModeContext'
 import { gamePlurals } from '../../../../utils/pluralization'
-import { useArcadeMemoryPairs } from '../context/ArcadeMemoryPairsContext'
+import { useMemoryPairs } from '../context/MemoryPairsContext'
 
 interface PlayerStatusBarProps {
   className?: string
@@ -11,7 +11,7 @@ interface PlayerStatusBarProps {
 
 export function PlayerStatusBar({ className }: PlayerStatusBarProps) {
   const { players: playerMap, activePlayers: activePlayerIds } = useGameMode()
-  const { state } = useArcadeMemoryPairs()
+  const { state } = useMemoryPairs()
 
   // Get active players array
   const activePlayersData = Array.from(activePlayerIds)

apps/web/src/app/arcade/matching/components/ResultsPhase.tsx

@@ -3,12 +3,12 @@
 import { useRouter } from 'next/navigation'
 import { css } from '../../../../../styled-system/css'
 import { useGameMode } from '../../../../contexts/GameModeContext'
-import { useArcadeMemoryPairs } from '../context/ArcadeMemoryPairsContext'
+import { useMemoryPairs } from '../context/MemoryPairsContext'
 import { formatGameTime, getMultiplayerWinner, getPerformanceAnalysis } from '../utils/gameScoring'
 
 export function ResultsPhase() {
   const router = useRouter()
-  const { state, resetGame, activePlayers, gameMode } = useArcadeMemoryPairs()
+  const { state, resetGame, activePlayers, gameMode, exitSession } = useMemoryPairs()
   const { players: playerMap, activePlayers: activePlayerIds } = useGameMode()
 
   // Get active player data array

apps/web/src/app/arcade/matching/context/MemoryPairsContext.tsx

@@ -251,7 +251,7 @@ function memoryPairsReducer(state: MemoryPairsState, action: MemoryPairsAction):
 }
 
 // Create context
-const MemoryPairsContext = createContext<MemoryPairsContextValue | null>(null)
+export const MemoryPairsContext = createContext<MemoryPairsContextValue | null>(null)
 
 // Provider component
 export function MemoryPairsProvider({ children }: { children: ReactNode }) {

apps/web/src/app/arcade/matching/context/RoomMemoryPairsProvider.tsx

@@ -39,6 +39,8 @@ const initialState: MemoryPairsState = {
   originalConfig: undefined,
   pausedGamePhase: undefined,
   pausedGameState: undefined,
+  // HOVER: Initialize hover state
+  playerHovers: {},
 }
 
 /**
@@ -194,6 +196,17 @@ function applyMoveOptimistically(state: MemoryPairsState, move: GameMove): Memor
       }
     }
 
+    case 'HOVER_CARD': {
+      // Update player hover state for networked presence
+      return {
+        ...state,
+        playerHovers: {
+          ...state.playerHovers,
+          [move.playerId]: move.data.cardId,
+        },
+      }
+    }
+
     default:
       return state
   }
@@ -514,6 +527,22 @@ export function RoomMemoryPairsProvider({ children }: { children: ReactNode }) {
     })
   }, [canResumeGame, activePlayers, state.currentPlayer, sendMove])
 
+  const hoverCard = useCallback(
+    (cardId: string | null) => {
+      // HOVER: Send hover state for networked presence
+      // Use current player as the one hovering
+      const playerId = state.currentPlayer || activePlayers[0] || ''
+      if (!playerId) return // No active player to send hover for
+
+      sendMove({
+        type: 'HOVER_CARD',
+        playerId,
+        data: { cardId },
+      })
+    },
+    [state.currentPlayer, activePlayers, sendMove]
+  )
+
   // NO MORE effectiveState merging! Just use session state directly with gameMode added
   const effectiveState = { ...state, gameMode } as MemoryPairsState & { gameMode: GameMode }
 
@@ -536,6 +565,7 @@ export function RoomMemoryPairsProvider({ children }: { children: ReactNode }) {
     setGameType,
     setDifficulty,
     setTurnTimer,
+    hoverCard,
     exitSession,
     gameMode,
     activePlayers,
@@ -543,3 +573,6 @@ export function RoomMemoryPairsProvider({ children }: { children: ReactNode }) {
 
   return <MemoryPairsContext.Provider value={contextValue}>{children}</MemoryPairsContext.Provider>
 }
+
+// Export the hook for this provider
+export { useMemoryPairs } from './MemoryPairsContext'

apps/web/src/app/arcade/matching/context/index.ts

@@ -0,0 +1,20 @@
+/**
+ * Central export point for arcade matching game context
+ * Re-exports the hook from the appropriate provider
+ */
+
+// Export the hook (works with both local and room providers)
+export { useMemoryPairs } from './MemoryPairsContext'
+
+// Export the room provider (networked multiplayer)
+export { RoomMemoryPairsProvider } from './RoomMemoryPairsProvider'
+
+// Export types
+export type {
+  GameCard,
+  GameMode,
+  GamePhase,
+  GameType,
+  MemoryPairsState,
+  MemoryPairsContextValue,
+} from './types'

apps/web/src/app/arcade/matching/context/types.ts

@@ -59,6 +59,7 @@ export interface MemoryPairsState {
   moves: number
   scores: PlayerScore
   activePlayers: Player[] // Track active player IDs
+  playerMetadata?: { [playerId: string]: any } // Player metadata for cross-user visibility
   consecutiveMatches: { [playerId: string]: number } // Track consecutive matches per player
 
   // Timing
@@ -72,6 +73,24 @@ export interface MemoryPairsState {
   isProcessingMove: boolean
   showMismatchFeedback: boolean
   lastMatchedPair: [string, string] | null
+
+  // PAUSE/RESUME: Paused game state
+  originalConfig?: { gameType: GameType; difficulty: Difficulty; turnTimer: number }
+  pausedGamePhase?: GamePhase
+  pausedGameState?: {
+    gameCards: GameCard[]
+    currentPlayer: Player
+    matchedPairs: number
+    moves: number
+    scores: PlayerScore
+    activePlayers: Player[]
+    playerMetadata: { [playerId: string]: any }
+    consecutiveMatches: { [playerId: string]: number }
+    gameStartTime: number | null
+  }
+
+  // HOVER: Networked hover state
+  playerHovers?: { [playerId: string]: string | null }
 }
 
 export type MemoryPairsAction =
@@ -102,12 +121,20 @@ export interface MemoryPairsContextValue {
   gameMode: GameMode // Derived from global context
   activePlayers: Player[] // Active player IDs from arena
 
+  // PAUSE/RESUME: Computed pause/resume values
+  hasConfigChanged?: boolean
+  canResumeGame?: boolean
+
   // Actions
   startGame: () => void
   flipCard: (cardId: string) => void
   resetGame: () => void
   setGameType: (type: GameType) => void
   setDifficulty: (difficulty: Difficulty) => void
+  setTurnTimer?: (timer: number) => void
+  goToSetup?: () => void
+  resumeGame?: () => void
+  hoverCard?: (cardId: string | null) => void
   exitSession: () => void
 }
 

apps/web/src/app/arcade/matching/page.tsx

@@ -1,13 +1,13 @@
 import { ArcadeGuardedPage } from '@/components/ArcadeGuardedPage'
 import { MemoryPairsGame } from './components/MemoryPairsGame'
-import { ArcadeMemoryPairsProvider } from './context/ArcadeMemoryPairsContext'
+import { RoomMemoryPairsProvider } from './context/RoomMemoryPairsProvider'
 
 export default function MatchingPage() {
   return (
     <ArcadeGuardedPage>
-      <ArcadeMemoryPairsProvider>
+      <RoomMemoryPairsProvider>
         <MemoryPairsGame />
-      </ArcadeMemoryPairsProvider>
+      </RoomMemoryPairsProvider>
     </ArcadeGuardedPage>
   )
 }

apps/web/src/app/arcade/room/page.tsx

@@ -2,7 +2,7 @@
 
 import { useRoomData } from '@/hooks/useRoomData'
 import { MemoryPairsGame } from '../matching/components/MemoryPairsGame'
-import { ArcadeMemoryPairsProvider } from '../matching/context/ArcadeMemoryPairsContext'
+import { RoomMemoryPairsProvider } from '../matching/context/RoomMemoryPairsProvider'
 
 /**
  * /arcade/room - Renders the game for the user's current room
@@ -68,9 +68,9 @@ export default function RoomPage() {
   switch (roomData.gameName) {
     case 'matching':
       return (
-        <ArcadeMemoryPairsProvider>
+        <RoomMemoryPairsProvider>
           <MemoryPairsGame />
-        </ArcadeMemoryPairsProvider>
+        </RoomMemoryPairsProvider>
       )
 
     // TODO: Add other games (complement-race, memory-quiz, etc.)

apps/web/src/app/games/matching/context/types.ts

@@ -103,6 +103,9 @@ export interface MemoryPairsState {
   isProcessingMove: boolean
   showMismatchFeedback: boolean
   lastMatchedPair: [string, string] | null
+
+  // Hover state for networked presence
+  playerHovers: { [playerId: string]: string | null } // playerId -> cardId (or null if not hovering)
 }
 
 export type MemoryPairsAction =
@@ -143,6 +146,7 @@ export interface MemoryPairsContextValue {
   setGameType: (type: GameType) => void
   setDifficulty: (difficulty: Difficulty) => void
   setTurnTimer: (timer: number) => void
+  hoverCard: (cardId: string | null) => void // Send hover state for networked presence
   goToSetup: () => void
   exitSession: () => void // Exit arcade session (no-op for non-arcade mode)
 }

apps/web/src/lib/arcade/validation/MatchingGameValidator.ts

@@ -44,6 +44,9 @@ export class MatchingGameValidator implements GameValidator<MemoryPairsState, Ma
       case 'RESUME_GAME':
         return this.validateResumeGame(state)
 
+      case 'HOVER_CARD':
+        return this.validateHoverCard(state, move.data.cardId, move.playerId)
+
       default:
         return {
           valid: false,
@@ -479,6 +482,31 @@ export class MatchingGameValidator implements GameValidator<MemoryPairsState, Ma
     }
   }
 
+  /**
+   * Validate hover state update for networked presence
+   *
+   * Hover moves are lightweight and always valid - they just update
+   * which card a player is hovering over for UI feedback to other players.
+   */
+  private validateHoverCard(
+    state: MemoryPairsState,
+    cardId: string | null,
+    playerId: string
+  ): ValidationResult {
+    // Hover is always valid - it's just UI state for networked presence
+    // Update the player's hover state
+    return {
+      valid: true,
+      newState: {
+        ...state,
+        playerHovers: {
+          ...state.playerHovers,
+          [playerId]: cardId,
+        },
+      },
+    }
+  }
+
   isGameComplete(state: MemoryPairsState): boolean {
     return state.gamePhase === 'results' || state.matchedPairs === state.totalPairs
   }
@@ -516,6 +544,8 @@ export class MatchingGameValidator implements GameValidator<MemoryPairsState, Ma
       originalConfig: undefined,
       pausedGamePhase: undefined,
       pausedGameState: undefined,
+      // HOVER: Initialize hover state
+      playerHovers: {},
     }
   }
 }

apps/web/src/lib/arcade/validation/types.ts

@@ -61,6 +61,13 @@ export interface MatchingResumeGameMove extends GameMove {
   data: Record<string, never>
 }
 
+export interface MatchingHoverCardMove extends GameMove {
+  type: 'HOVER_CARD'
+  data: {
+    cardId: string | null // null when mouse leaves card
+  }
+}
+
 export type MatchingGameMove =
   | MatchingFlipCardMove
   | MatchingStartGameMove
@@ -68,6 +75,7 @@ export type MatchingGameMove =
   | MatchingGoToSetupMove
   | MatchingSetConfigMove
   | MatchingResumeGameMove
+  | MatchingHoverCardMove
 
 // Generic game state union
 export type GameState = MemoryPairsState // Add other game states as union later

package.json

@@ -1,6 +1,6 @@
 {
   "name": "soroban-monorepo",
-  "version": "2.11.0",
+  "version": "2.12.2",
   "private": true,
   "description": "Beautiful Soroban Flashcard Generator - Monorepo",
   "workspaces": [