Gas sponsorship

Parchment can pay the Sui network gas for one-click trades: trades signed by a session key that your wallet registered once as a trading delegate of your account. Nothing else is sponsored.

Sponsorship is available when Parchment enables it.

What is sponsored

Only these delegate trade transactions:

• open request, close request (including Close All), cancel, emergency close, and closing a position on a retired market.

You always pay your own gas for everything else: creating your account, deposits, withdrawals, turning one-click trading on or off, staking, claims, and any trade your wallet signs directly. Keep a little SUI in your wallet.

The app shows a short reason and lets you send the trade from your wallet, paying the gas yourself, when:

• sponsorship is off or out of funds,
• a per-account limit is reached,
• the trade needs more gas than the sponsor covers,
• your one-click session has ended.

If another sponsored trade is still in flight, the app retries once and then says one-click is busy. A trade that would fail on chain (for example while paused) is not retried with wallet-paid gas.

The keeper pays the gas for filling your orders, funded by the execution fee.

For developers: the session proof

Request sponsorship with POST /sponsor:

{
  "sender": "0x<session key address>",
  "txKindBase64": "<base64 BCS TransactionKind from the transaction builder>",
  "senderSignature": "<base64 Ed25519 signature of the session proof>",
  "expiresAtMs": "1761091234567n"
}

The session key signs, as a Sui personal message, the UTF-8 bytes of exactly these five lines joined by \n, with no trailing newline:

Parchment session-key sponsorship v1
sender: <sender>
accountId: <account>
txKindSha256: <sha256>
expiresAtMs: <expiresAtMs>

• sender and accountId are 0x plus 64 lowercase hex digits. accountId is the Parchment account the trade targets.
• txKindSha256 is the lowercase hex SHA-256 of the transaction kind bytes (the base64-decoded txKindBase64).
• expiresAtMs is Unix milliseconds, plain decimal in the message and an n string in the request. It must be in the future and at most 120 seconds ahead of the service's clock.
• Only Ed25519 signatures are accepted, and the signer's address must be sender. sender must be a live delegate of the account.

The response carries txBytesBase64 and sponsorSignature. Sign txBytesBase64 with the session key and execute it with both signatures.