As a solver in the cross-chain ecosystem, you’re likely focused on:

  • Accessing reliable order flow
  • Minimizing user escrow unlock times to reduce inventory requirements
  • Having flexibility in your liquidity sources

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How LI.FI Intent Helps

  • Direct access to LI.FI’s significant order flow
  • Freedom to use any liquidity source for solving (e.g., DEXs, CEXs, or your own inventory)
  • Fast user escrow unlock times (typically less than 2 minutes)
  • Lower capital requirements due to quick repayment cycles

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Solving Intents

LI.FI intent is an entirely permissionless system. Since the system is componentized and components have no inherent trust elements with other components, they can be mixed and matched as desired by users. As a result, it is important that you validate orders in their entirety once received. The general flow is:

  1. The sponsor signs the LI.FI intent-compatible lock and sends it to the LI.FI order server.

  2. The LI.FI order server preliminarily validates the order and obtains the allocator co-signature for the order. It is then broadcasted to solvers.

  3. A solver submits the order’s output to the output settlement contract, starting the oracle system.

    Output Settlement is denoted as the output.settler.

  4. The proof is delivered to the input chain through the validation layer.

    Oracle system is denoted as the localOracle and output.oracle in the order struct.

  5. The solver submits the order to the input settlement contract, verifying the delivery and unlocking the associated input tokens.

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Order Types

LI.FI uses three order structures, listed from least to most verbose:

  1. BatchClaim: A signed intent that allows for claiming input assets.
  2. StandardOrder: An on-chain definition containing enough information to convey the intent.
  3. Order Server response: A hydrated order with additional information that may be helpful to solvers.

Unless you are verifying order signatures, you won’t interact with BatchClaim. All on-chain interactions use StandardOrder to standardize interfaces. However, StandardOrder does not contain enough information to fill intents. As a result, it is hydrated off-chain with InputSolver, signatures, and more.

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Collecting Orders

LI.FI Intents offers two ways to receive orders:

  1. Recommended: Connect to the order server via WebSocket.
  2. Alternative: Monitor on-chain deposits through the deposit interface.

The order server is the recommended integration surface for most solvers. However, if you are interested in the lowest latency, decentralized, and permissionless order discovery, you can read some orders on-chain. Not all orders will be discoverable on-chain. From either source, you will receive a StandardOrder and other fill details to be submitted across all VMs:

struct StandardOrder {
    address user;
    uint256 nonce;
    uint256 originChainId;
    uint32 expires;
    uint32 fillDeadline;
    address localOracle;
    uint256[2][] inputs;
    MandateOutput[] outputs;
}

Where uint256[2][] inputs === [uint256 tokenId, uint256 amount][] and MandateOutput is:

struct MandateOutput {
    bytes32 oracle;
    bytes32 settler;
    uint256 chainId;
    bytes32 token;
    uint256 amount;
    bytes32 recipient;
    bytes call;
    bytes context;
}

For more information on collecting orders, View Order Collection Guide →

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Filling Intents

To fill intents, all MandateOutputs must be executed. Each MandateOutput is a self-contained execution description.

  • output.settler defines the execution with its associated context and should be called on its interface. Currently, only one OutputSettler is implemented: OutputSettlerCoin.sol, which has two interfaces for filling:
/// @notice For implementing own batching functionality
function fill(
    uint32 fillDeadline,
    bytes32 orderId,
    MandateOutput calldata output,
    bytes32 proposedSolver
) external returns (bytes32 actualSolver);

/// @notice For batch filling entire orders.
function fillOrderOutputs(
    uint32 fillDeadline,
    bytes32 orderId,
    MandateOutput[] calldata outputs,
    bytes32 proposedSolver
) external;

For more information about filling intents View EVM Order Filling Guide →

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Validating Fills

After filling intents, the proof of fill has to be sent to the input chain. The oracle system used for the order is specified through localOracle and output.oracle. These should match. However, validating filled outputs is highly oracle specific. For more, View Oracle System Architecture -> ->

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Settling Orders

Lastly, intents have to be settled before their expiry. This is achieved by calling finalise[withSignature] on the designated InputSettler. The caller has to be the designated solver set on fill.

function finalise(
    StandardOrder calldata order,
    bytes calldata signatures,
    uint32[] calldata timestamps,
    bytes32[] memory solvers,
    bytes32 destination,
    bytes calldata call
) external;

For more information about settling orders View Order Settlement Guide →