Sui’s object versioning ensures deterministic outcomes in parallel transaction execution by tracking object versions and resolving conflicts via consensus (Narwhal/Bullshark). Intermediate developers must handle versioning to avoid conflicts in shared objects.

module leaderboard::shared_leaderboard {
    use sui::object::{Self, UID};
    use sui::tx_context::{Self, TxContext};
    use sui::transfer;
    use sui::dynamic_field as df;

    struct Leaderboard has key {
        id: UID,
    }

    // Create shared leaderboard
    public entry fun create_leaderboard(ctx: &mut TxContext) {
        let leaderboard = Leaderboard { id: object::new(ctx) };
        transfer::share_object(leaderboard);
    }

    // Update user score (Sui versioning ensures atomic updates)
    public entry fun update_score(leaderboard: &mut Leaderboard, user: address, score: u64) {
        df::add(&mut leaderboard.id, user, score);
        // Sui’s consensus ensures versioned updates are ordered
    }

    // Get user score
    public fun get_score(leaderboard: &Leaderboard, user: address): u64 {
        if (df::exists_(&leaderboard.id, user)) {
            *df::borrow(&leaderboard.id, user)
        } else {
            0
        }
    }
}

How does Sui’s object versioning prevent race conditions? Write a Move module for a shared leaderboard where users update scores, and explain how Sui ensures consistency if multiple users update simultaneously.