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aztec-fee

Fee payment strategies for Aztec transactions. Each strategy produces an ExecutionPayload that is merged into the user’s tx before submission.

Source: crates/fee/src/.

The FeePaymentMethod Trait

#[async_trait]
pub trait FeePaymentMethod: Send + Sync {
    /// The asset used for payment (for fee-juice methods, this is the Fee Juice protocol contract).
    async fn get_asset(&self) -> Result<AztecAddress, Error>;

    /// The account paying the fee.
    async fn get_fee_payer(&self) -> Result<AztecAddress, Error>;

    /// The function calls + authwits that actually perform the payment.
    async fn get_fee_execution_payload(&self) -> Result<ExecutionPayload, Error>;
}

Shipped Strategies

TypeUse when
NativeFeePaymentMethodThe sending account already holds Fee Juice.
SponsoredFeePaymentMethodA public sponsor contract will pay unconditionally (typical for onboarding flows / test sandboxes).
FeeJuicePaymentMethodWithClaimFirst-time payer whose Fee Juice has been deposited on L1 and needs to be claimed on L2 before paying.

Supporting Types

  • L2AmountClaim — the claim tuple produced from an L1 deposit and consumed by FeeJuicePaymentMethodWithClaim.

Choosing a Strategy

SituationStrategy
Established account with Fee JuiceNativeFeePaymentMethod
Sandbox / sponsored onboardingSponsoredFeePaymentMethod
Deploying a fresh account that was funded via FeeJuicePortal on L1FeeJuicePaymentMethodWithClaim

Private Fee Payment Contract (FPC) support is on the roadmap but is not currently shipped in this crate; consumers requiring private FPC flows need to implement FeePaymentMethod themselves.

Typical Use

use aztec_fee::{FeePaymentMethod, NativeFeePaymentMethod};

let payment = NativeFeePaymentMethod::new(account_address);
let payload = payment.get_fee_execution_payload().await?;
// The wallet merges `payload` with the user's call payload.

Full API

Bundled rustdoc: api/aztec_fee/. Local regeneration:

cargo doc -p aztec-fee --open

See Also