Onchain

Addresses, instructions and events, and how to check the reserve and any request.

The Unspent program runs on Solana. It holds the USDC behind every credit, keeps every API balance and records every request.

Addresses

Accounts

All of them are program-derived addresses of the program above.

Instructions

What the admin and the gateway can't do

• Move credits out of API balances or USDC out of the reserve other than through the instructions above. The gateway can only burn what a request it held settles for, never more than the hold.
• Block withdrawals or expiry. Neither needs anyone's approval, and pauses don't stop them.
• Make a change fast. Raising a limit, changing the treasury, the backup gateway key or the delay itself takes 48 hours and is visible onchain as a pending change from the start. Withdrawals are instant, so everyone has time to leave before a change applies.
• Sweep more than the surplus. sweep_surplus takes only USDC above the credits in circulation, for example USDC left behind by credits someone burned themselves. It never touches balances or holds.

Program upgrades

Every credit is backed by 1 USDC as long as the program's code is the code described here. Until upgrades are frozen, the upgrade authority can replace that code, so the backing also depends on whoever holds that key.

Upgrade authority right now: held by 9PeMBb8kkpRDwRDEQYREgQkqkJKKmbMx1wXzFmoyHNcM.

Check the reserve

• Credits in circulation: the supply of the credit mint.
• USDC in reserve: the balance of the reserve account.

The reserve is never smaller than the supply. /reserve shows both live with the coverage, totals and the latest settlements. Any Solana explorer shows the same numbers.

Check a request

Every API response carries x-unspent-request-id: the request's 32-byte id in hex. Its reservation address is derived from it, and that address's history holds the request's two transactions: reserve and then settle (or expire if it never settled).

import { createSolanaRpc, getProgramDerivedAddress } from "@solana/kit";

const requestId = "3f9c0e…"; // x-unspent-request-id
const [reservation] = await getProgramDerivedAddress({
  programAddress: "5YSrsYtX6UnSx8KAbiD8RWM7UzNNXU3w5QhxSA2vvfkx",
  seeds: ["res", Uint8Array.from(Buffer.from(requestId, "hex"))],
});
const rpc = createSolanaRpc("https://api.mainnet-beta.solana.com");
const history = await rpc.getSignaturesForAddress(reservation).send();

The reserve transaction logs a Reserved event with the hold. The settle transaction logs a Settled event with actual: what the request cost. Settlements are batched, so one settle_many transaction can settle several requests. /app/usage links both transactions of every request.

Events

Events are Anchor events in the program's logs. Amounts are in base units: 1 credit is 1,000,000.