Implement Batch Market Creation in CTFExchange Contract

Issue #96 | State: OPEN | Created: 2026-01-27T07:31:51Z

Updated: 2026-01-27T07:31:51Z | Closed: N/A

Problem Description

When creating multiple markets in rapid succession (e.g., creating a group of markets via the API), we encounter the REPLACEMENT_UNDERPRICED (replacement fee too low) error.

This occurs because we are sending multiple distinct transactions (one for each market) from the same account (Server Wallet) almost simultaneously. If the network hasn't mined the first transaction yet, the subsequent transactions with higher nonces or same nonces can conflict or be treated as replacements without sufficient gas price bumps.

While we implemented a client-side fix using sequential nonce management (tracking currentNonce locally), this is a fragile solution that relies on perfect synchronization with the blockchain state.

Error Log

Failed: replacement fee too low (transaction="0xf90...", info={ "error": { "code": -32000, "message": "replacement transaction underpriced" } }, code=REPLACEMENT_UNDERPRICED)

Proposed Solution: Batch Processing in Smart Contract

Instead of forcing the backend to manage nonces for N separate transactions, the CTFExchange smart contract should support a Batch Market Creation function.

Recommendation

Add a function createBinaryMarketBatch to the CTFExchange contract.

function createBinaryMarketBatch(
    bytes32[] calldata conditionIds, 
    string[] calldata titles, 
    uint256[] calldata endTimes
    // ... other necessary parameters
) external {
    require(conditionIds.length == titles.length, "Mismatched arrays");
    
    for (uint i = 0; i < conditionIds.length; i++) {
        _createBinaryMarket(conditionIds[i], titles[i], endTimes[i]);
    }
}

Benefits

1. Atomicity: All markets in a group are created in a single transaction.
2. Gas Efficiency: Reduces base transaction overhead.
3. Reliability: Eliminates REPLACEMENT_UNDERPRICED errors entirely for group creation.
4. Simpler Backend: The API no longer needs complex manual nonce tracking re-sync logic.