The problem OptionArena solves

Options are the biggest market in traditional finance and almost nobody in crypto touches them, because every interface assumes you already speak the language: strike, expiry, delta, implied volatility.

OptionArena takes a plain-English market view, turns it into a defined-risk options position on the live Thetanuts V4 book on Base mainnet, and shows the maximum loss as a dollar figure before anything is signed. Around that sits a social layer: handles, friends, head-to-head battles on a shared expiry, and a leaderboard where you choose what "winning" means.

Copy trading is sourced from Deribit rather than Thetanuts. A young venue has nobody worth copying yet, so we rank live Deribit flow and map each trade onto the nearest fillable Thetanuts contract, surfacing every difference in strike, expiry or direction rather than silently substituting. That direction came from the Thetanuts team directly, and it means the product brings Thetanuts order flow it doesn't currently have.

We deploy no contracts of our own — only calls to Thetanuts' deployed OptionBook on Base (chain 8453).

The buyable side of the book is physically settled and reverts on-chain with Panic(0x11). We ruled out size, order choice, expiry, SDK version, RPC and allowance across 62 orders, then decoded a successful fill against our own calldata word by word; the Thetanuts team confirmed physical settlement is not yet routed into the SDK. Execution therefore routes through the sell side. The full investigation is in docs/decisions.md §14.

Challenges we ran into

The buyable side of the book reverts. Every order we could buy failed with Panic(0x11), a Solidity arithmetic overflow raised inside the OptionBook. We ruled out trade size across nine amounts, all 62 USDC-priced buyable orders, order expiry, SDK version, three independent RPCs and the token allowance. Then we decoded a fill that had succeeded an hour earlier against our own calldata, word by word, and found ours was one 32-byte word longer — the extraOptionData a physically settled contract carries. The fills that work are cash-settled and collateralised in plain USDC; everything we could buy was physical. The Thetanuts team confirmed physical settlement isn't routed into the SDK yet. We built a sell path around it and made the app refuse physicals outright rather than broadcast a transaction we already know reverts.

Decimals nearly bit us. We assumed a fixed size decimal and read a call's remaining size as 4099251066830 USDC instead of 4.09 WETH. The real rule — a contract count uses the same decimals as its collateral token — is documented nowhere and had to be derived from the live book.

Order identity was wrong twice. We first keyed orders by nonce, but 72 orders shared 13 nonces and one nonce spanned 18 contracts across different strikes and expiries. We switched to a content hash — then found it expired within seconds, because makers requote about once a minute. Excluding price and nonce from the hash and adding a 2% slippage check fixed it.

Cold start on copy trading. Thetanuts has under $1M TVL, so there is nobody to copy. We source signals from Deribit instead and map them onto Thetanuts contracts, reporting every difference in strike, expiry or direction rather than silently substituting.