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Writing an Option

You sign once. The bot does the rest. Three transactions happen in sequence — but you only touch the first one. Your collateral is locked in the smart contract within about a minute.

The User Experience

What You See

You fill in the option parameters — asset, strike price, expiry date, and how much collateral to lock. You sign one transaction in Nautilus. The progress tracker shows three stages: Create Definition, Mint Tokens, Deliver to Wallet. About a minute later, your tradeable option tokens are sitting in your wallet, ready to list for sale.

Screenshot: Write option form + progress tracker
Under the Hood

Three Transactions, One Signature

TX 1 — CREATE (you sign this)
Your collateral leaves your wallet and goes into a “definition box” at the contract address. This box holds your collateral plus a small ERG deposit (~0.013 ERG) that covers miner fees for the next two automated steps.

YOUR WALLETCollateral (rsToken/ERG)+ 0.013 ERG (covers 3 TX fees)+ 0.01 ERG platform feeYOU SIGNDEFINITION BOXR4: option nameR8: 11 numerical paramsR9: issuer key + fee addrOptionReserveV4
On-chain detailThe definition box sits at the OptionReserveV4 contract address. R4 holds the option name, R8 holds 11 numerical parameters (type, style, strike, expiry, etc.), R9 holds your public key and the fee address. No tokens are minted yet — this is just a deposit.

TX 2 — MINT (bot does this automatically)
The bot detects your definition box and creates the option tokens. In Ergo, a new token's ID always equals the ID of the first input box — so the option token ID is guaranteed to be unique and unforgeable. The bot takes the 0.01 ERG mint fee from your deposit and sends it to the platform fee address.

DEFINITION BOXcollateral + ERG depositno tokens yetBOT MINTSRESERVE BOXN+1 option tokens minted+ all collateral preservedFEE BOX0.01 ERG to Etcha
On-chain detailThe mint TX has INPUTS.size == 1 (just the definition box) and OUTPUTS.size == 3 (reserve, fee, miner). The contract validates the token count formula, checks the Token Registry to confirm the collateral matches the oracle feed, and verifies the fee output goes to the address stored in R9[1].

TX 3 — DELIVER (bot does this automatically)
The bot splits the reserve: it keeps the singleton in the contract and sends the tradeable tokens to your wallet. Now you hold N option tokens, ready to sell.

RESERVE (N+1 TOKENS)collateral lockedN tradeable + 1 singletonN tokensRESERVE (1 SINGLETON)collateral stays lockedYOUR WALLETN tradeable option tokens
On-chain detailThe contract checks isMinted && !isOptionDelivered, verifies the singleton stays in OUTPUT[0] with tokens(0)._2 == 1, and sends N tokens to the issuer address from R9[0]. All registers are preserved in the successor box.
Token Count

How Many Tokens?

The number of tradeable tokens depends on how much collateral you lock. The contract divides your total collateral by the per-contract amount, then adds one extra token — the singleton — that stays locked in the reserve forever as a receipt proving the contract exists.

Example: Gold Call (DexyGold collateral)
1
You lock 93 DexyGold for a 0.001 oz/contract option. Each contract needs 31 DexyGold (0.001 oz × 31,103 mg/oz).
93 / 31 = 3 tradeable tokens + 1 singleton = 4 total
2
You lock 6 rsADA for a 2 ADA/contract option. Each contract needs 2,000,000 raw rsADA.
6,000,000 / 2,000,000 = 3 tradeable + 1 singleton = 4 total
The +1 singletonThe singleton is a special token that stays locked in the reserve forever. It proves this contract exists and prevents the reserve from being drained. You never see it — it lives in the contract until the option is closed or all tokens are exercised.
Key Takeaway

You sign once. The bot handles mint and deliver automatically. Your collateral is locked in the contract — only the smart contract decides where it goes.