Convex Game Management

Convex Game Management

Overview

This skill handles the complete game lifecycle for PictionAI's multiplayer Pictionary game, including game creation, player management, turn-based rotation, atomic turn completion with scoring, and game state transitions.

Core Concepts

Game States

• waiting - Game created, players joining in lobby
• started - Game in progress, turns rotating
• finished - All rounds complete, winner determined

Turn States

• drawing - Active turn, timer running (60-120 seconds)
• completed - Turn finished with correct guess
• time_up - Timer expired, no points awarded

Atomic Turn System

Turns are completed atomically to ensure data consistency:

1. Start Turn: Drawer calls startNewTurn mutation
2. Draw & Guess Phase: Real-time canvas sync, players submit guesses
3. Turn Completion: Three atomic scenarios:
   • ✅ Correct guess → Both guesser and drawer earn points
   • 🏆 Manual winner selection → Drawer selects winner from guessers
   • ⏱️ Time up → No points, proceed to next turn
4. Score Updates: Dual scoring system (guesser time bonus + drawer base score)
5. Next Turn: Auto round-robin rotation to next player

Scoring System

Guess Scoring (Correct Answer)

• Guesser: Base 50 points + time bonus (50 - elapsed_seconds, min 5 points)
• Drawer: 25% of guesser's score, minimum 10 points

Drawer Scoring (Manual Winner)

• Selected Guesser: 30 points
• Drawer: 25 points

Key Mutations

startNewTurn

Start a new drawing turn, assign card, initialize timer.

mutation startNewTurn {
  args: {
    game_id: Id<"games">
  }
  // Returns: {
  //   turn_id: Id<"turns">,
  //   card: { word: string, category: string },
  //   drawer_id: Id<"users">,
  //   time_limit: number
  // }
}

submitGuessAndCompleteTurn

Submit a guess and complete the turn with atomic scoring.

mutation submitGuessAndCompleteTurn {
  args: {
    game_id: Id<"games">,
    turn_id: Id<"turns">,
    guesser_id: Id<"users">,
    guess: string,
    elapsed_time: number,
    is_correct?: boolean
  }
  // Handles three scenarios atomically:
  // 1. Correct guess → Award points to both
  // 2. Manual selection → Drawer chooses winner
  // 3. Time up → Skip to next turn
}

selectWinner (Manual Selection)

Drawer selects a guesser as the winner when time expires.

mutation selectWinner {
  args: {
    turn_id: Id<"turns">,
    selected_guesser_id: Id<"users">
  }
  // Awards 30 points to guesser, 25 to drawer
}

Key Queries

getGame

Fetch complete game state with players, current turn, scores.

query getGame {
  args: { game_id: Id<"games"> }
  // Returns full game with nested players, turns, scores
}

getGameTurns

Get all turns in a game with guesses and results.

query getGameTurns {
  args: { game_id: Id<"games"> }
  // Returns array of turns with scoring details
}

React Integration

// Start a new turn
const startTurn = useMutation(api.mutations.game.startNewTurn);
await startTurn({ game_id: gameId });

// Submit guess and complete turn
const submitGuess = useMutation(api.mutations.game.submitGuessAndCompleteTurn);
await submitGuess({
  game_id: gameId,
  turn_id: turnId,
  guesser_id: userId,
  guess: "elephant",
  elapsed_time: 45,
});

// Fetch game state
const game = useQuery(api.queries.games.getGame, { game_id: gameId });

Database Schema References

// Games table
games: defineTable({
  code: v.string(), // Unique game code
  creator_id: v.id("users"),
  players: v.array(
    v.object({
      user_id: v.id("users"),
      score: v.number(),
      is_drawer: v.boolean(),
    })
  ),
  state: v.union(
    v.literal("waiting"),
    v.literal("started"),
    v.literal("finished")
  ),
  current_turn_index: v.number(),
  created_at: v.optional(v.number()),
  round_count: v.number(),
});

// Turns table
turns: defineTable({
  game_id: v.id("games"),
  drawer_id: v.id("users"),
  card_id: v.id("cards"),
  state: v.union(
    v.literal("drawing"),
    v.literal("completed"),
    v.literal("time_up")
  ),
  timer_started_at: v.number(),
  time_limit: v.number(),
  correct_guesser_id: v.optional(v.id("users")),
  guesses: v.array(
    v.object({
      guesser_id: v.id("users"),
      guess: v.string(),
      timestamp: v.number(),
      is_correct: v.optional(v.boolean()),
    })
  ),
});

Common Patterns

Monitor active turn

const game = useQuery(api.queries.games.getGame, { game_id });
const currentTurn = game?.turns[game.current_turn_index];
const isMyTurn = currentTurn?.drawer_id === userId;

Handle turn completion

// When drawer completes turn with guess result
const completeWithCorrect = useMutation(
  api.mutations.game.submitGuessAndCompleteTurn
);
await completeWithCorrect({
  game_id: gameId,
  turn_id: turnId,
  guesser_id: guesserId,
  guess: "elephant",
  elapsed_time: 30,
  is_correct: true,
});

Automatic next turn

The mutation automatically:

1. Rotates drawer (round-robin through players)
2. Assigns new card
3. Starts timer
4. Updates game state

Edge Cases

• Multiple guesses per player: Allowed, only latest is scored
• Guess submitted after timer: System checks elapsed time on server
• Late guess arrival: Real-time subscription updates guess feed
• Manual selection ambiguity: Drawer must explicitly select one winner
• Game with 2 players: Drawer rotation still works with round-robin

See Also

• TURN_MANAGEMENT_ANALYSIS.md - Detailed atomic turn analysis
• convex/​mutations/​game.ts - Complete mutation implementations
• components/​game/​game-board.tsx - UI integration