Struct ApprovalBinding 

pub struct ApprovalBinding {
    pub chain_id: u64,
    pub payee_address: String,
    pub amount_minor_units: u128,
    pub token_symbol: String,
    pub token_contract: Option<String>,
    pub approval_expires_at: u64,
}

Approval-bound settlement parameters the caller MUST supply.

EIP-3009 authorizations are independently replay-able and are not, by themselves, tied to the approval that governs the spend. This binding requires the prepared authorization to be bound to its governing approval so a captured signature cannot be redirected to a different payee, inflated to a different amount, or replayed on a different chain.

This type is the seam to the governed-approval layer: once a verified [chio_core_types::capability::governance::GovernedApprovalToken] is available at the settlement layer, the caller derives these bound values from that token’s governed intent and passes them here. Until then, the caller is the trust boundary that MUST extract the values from the verified approval before calling prepare_transfer_with_authorization. Either way the bound values are asserted against the authorization and any mismatch fails closed.

The GovernedApprovalToken itself does not carry chain/amount/payee/token as discrete fields (they are folded into its governed_intent_hash), so this layer cannot re-derive them from the token alone; it asserts the explicitly-bound values the caller resolved from the verified intent.

Fields

chain_id: u64

Chain id the governing approval authorized the spend on. Must equal the EIP-3009 domain chain_id.

payee_address: String

Payee the governing approval authorized. Must equal the EIP-3009 authorization to address (case-insensitive hex / checksum).

amount_minor_units: u128

Amount in token minor units the governing approval authorized. Must equal the EIP-3009 authorization value.

token_symbol: String

Token/currency symbol the governing approval authorized (for example "USDC"). The chain id alone does not pin the token: a captured authorization for one token contract can otherwise be redirected to a different token on the same chain with the same payee and numeric amount. Each lane asserts its lane-specific token identity against this symbol (x402 accepted tokens, Circle token symbol). Compared case-insensitively after trimming.

token_contract: Option<String>

Token contract address the governing approval authorized (for example the USDC contract on the target chain). It is asserted against the EIP-3009 domain verifying_contract, which is the contract the signed transfer actually targets, so a captured authorization cannot be redirected to a different token contract on the same chain. Compared as parsed Address bytes so checksum vs lowercase hex compare equal.

REQUIRED for the EIP-3009 lane: prepare_transfer_with_authorization fails closed when this is None, because a symbol alone cannot pin the on-chain token. The field stays Option only because lanes that identify their token by symbol and have no contract to compare against (the x402 accepted-token list and the Circle token symbol) still bind via token_symbol and legitimately leave this None.

approval_expires_at: u64

Approval expiry as a Unix timestamp in seconds. The prepared authorization MUST NOT outlive the governing approval: when an EIP-3009 valid_before would let a signed transfer stay broadcastable past this instant, preparation fails closed. Binds the off-chain authorization window to the approval window so a captured signature cannot be broadcast after the approval that governs it has expired.

Implementations

impl ApprovalBinding

pub fn assert_dispatch( &self, lane: &str, dispatch: &Web3SettlementDispatchArtifact, ) -> Result<(), SettlementError>

Assert that a settlement dispatch matches the approval-bound spend.

pub fn assert_token_symbol( &self, lane: &str, lane_token_symbol: &str, ) -> Result<(), SettlementError>

Assert that a lane’s token symbol matches the approval-bound token.

Trait Implementations

impl Clone for ApprovalBinding

fn clone(&self) -> ApprovalBinding

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ApprovalBinding

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ApprovalBinding

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for ApprovalBinding

impl PartialEq for ApprovalBinding

fn eq(&self, other: &ApprovalBinding) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for ApprovalBinding

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for ApprovalBinding