VRF Subscription model

The Supra VRF V2 introduces a prepaid subscription model that provides enhanced controls for consumers. This document will walk you through the key features and functionalities of the Supra VRF prepaid subscription. Getting Whitelisted The subscription model requires users to be registered with a wallet address that can be used as the subscription manager and once it is whitelisted, it could be used to register any number of smart contracts to consume random numbers from Supra VRF.

Currently, the whitelisting process is manual and requires users to request whitelisting via this form which is then carried out by the Supra team. However, in the future, this process will become permissionless. Callback Gas Fee Management Supra VRF subscription operates on a prepaid model, where users can add funds to their subscription account to cover the gas fee for callback (response) transactions. It's important to note that the gas fee for the initial request transaction should be paid by the requester's smart contract.

Total Balance The total balance represents the amount of tokens held by a consumer in their prepaid subscription account.

Minimum Balance The minimum token balance is the threshold that consumers must maintain in order to submit new VRF requests and have them accepted for processing. If the total balance falls below the minimum balance, Supra VRF will halt the processing of new VRF requests from the consumer. However, Supra VRF will continue processing already accepted or in-progress requests until the subscription is topped up.

Effective Balance The effective balance is calculated by subtracting the minimum balance from the total balance. This balance is used to track prepaid funds and send reminders to users to refill their accounts. When the effective balance falls below certain thresholds, email reminders will be sent to prompt users to top up their subscription balance.

Reminder	Logic
First Reminder	Effective balance <= 50% of minimum balance
Second Reminder	Effective balance <=25% of minimum balance
Third Reminder	Effective Balance <=10% of minimum balance
Fourth Reminder	Effective balance <=5% of minimum balance
Final Reminder	Effective balance <=minimum balance

Gas Fee Reconciliation Process This process ensures that the total balances of consumers are accurate. Here's how it works:

Gas Fee Deduction: Before a transaction is processed, Supra deducts an estimated gas fee from the total balance. This deduction is made upfront to cover the anticipated gas cost of the transaction.

Updating the correct balance following the transaction, a predefined time is set for the gas fee reconciliation process. where Supra calculates the actual gas fee incurred and adds the remainder to the total balance.

If you have any further questions or need assistance, please feel free to reach out to our support team.