Introduction
Core Lane uses an intent-based transaction system that allows users to express desired outcomes rather than specific execution paths. Intents are submitted to the network, locked by solvers, and fulfilled when specific conditions are met.
Intent Types
The system supports two primary intent types defined in the IntentType enum:
#[repr(u8)]
pub enum IntentType {
AnchorBitcoinFill = 1,
RiscVProgram = 2,
}
- AnchorBitcoinFill (type 1): Cross-chain bridge intents that lock value on Core Lane in exchange for Bitcoin payments
- RiscVProgram (type 2): Programmable intents that execute RISC-V programs to determine validity conditions
Intent Data Structure
All intents use the IntentData structure which wraps the intent type and CBOR-encoded data:
pub struct IntentData {
pub intent_type: IntentType,
pub data: Vec<u8>,
}
CBOR Serialization
Intents are serialized using CBOR (Concise Binary Object Representation) with the Ciborium library:
// Serialize intent to CBOR
let cbor_bytes = intent_data.to_cbor()?;
// Deserialize CBOR back to IntentData
let intent_data = IntentData::from_cbor(&cbor_bytes)?;
Intent Lifecycle
Intents progress through several states tracked by IntentStatus:
pub enum IntentStatus {
Submitted, // Initial state after creation
Locked(Address), // Locked by a solver (contains solver address)
Solved, // Successfully fulfilled
Cancelled, // Cancelled by creator
}
Intent State Transitions
- Creation: User creates intent via
intent() or intentFromBlob()
- Locking: Solver calls
lockIntentForSolving() to claim the intent
- Solving: Solver calls
solveIntent() with proof data
- Cancellation: Creator can call
cancelIntent() if not solved
Intent Structure
The full Intent object stored on-chain:
pub struct Intent {
pub data: Bytes, // CBOR-encoded intent data
pub value: u64, // Locked value in wei (max ~18.4 ETH)
pub status: IntentStatus, // Current status
pub last_command: IntentCommandType,// Last operation performed
pub creator: Address, // Intent creator
}
Intent values are currently limited to u64::MAX (~18.4 ETH in wei) for compatibility. Future versions will support arbitrary U256 values.
Intent System Interface
The intent system is accessed through a special contract address at 0x0000000000000000000000000000000000000045 (ExitMarketplace).
Core Functions
Creating Intents
// Submit intent with inline data
function intent(bytes intentData, uint256 nonce) payable returns (bytes32 intentId);
// Submit intent referencing stored blob
function intentFromBlob(bytes32 blobHash, uint256 nonce, bytes extraData) payable returns (bytes32 encumberFromBlob);
// Create and immediately lock intent (EIP-712 signature)
function createIntentAndLock(bytes eip712sig, bytes lockData) returns (bytes32 intentId);
Managing Intents
// Lock an intent for solving
function lockIntentForSolving(bytes32 intentId, bytes data) payable;
// Submit solution proof
function solveIntent(bytes32 intentId, bytes data) payable;
// Cancel an intent (creator only)
function cancelIntent(bytes32 intentId, bytes data) payable;
// Cancel solver lock
function cancelIntentLock(bytes32 intentId, bytes data) payable;
Query Functions
// Check if intent is solved
function isIntentSolved(bytes32 intentId) view returns (bool);
// Get current locker address
function intentLocker(bytes32 intentId) view returns (address);
// Get locked value
function valueStoredInIntent(bytes32 intentId) view returns (uint256);
Intent ID Calculation
Intent IDs are deterministically calculated using the creator address, nonce, and intent data:
fn calculate_intent_id(creator: Address, nonce: u64, data: Bytes) -> B256 {
keccak256(abi.encodePacked(creator, nonce, data))
}
Blob Storage
Large intent data can be stored as blobs to reduce transaction costs:
// Store blob data
function storeBlob(bytes data, uint256 expiryTime) payable;
// Check if blob exists
function blobStored(bytes32 blobHash) view returns (bool);
// Extend blob expiration
function prolongBlob(bytes32 blobHash) payable;
keccak256(data).
Creating Intents in Rust
Example creating an AnchorBitcoinFill intent:
use core_lane::intents::create_anchor_bitcoin_fill_intent;
let intent_data = create_anchor_bitcoin_fill_intent(
"bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh", // Bitcoin address
U256::from(1_000_000_000_000_000_000u64), // 1 ETH in wei
U256::from(50_000), // Max fee in sats
1735689600, // Expiry timestamp
)?;
let cbor_bytes = intent_data.to_cbor()?;
Intent Commands
The system tracks the last command executed on each intent:
pub enum IntentCommandType {
Created = 1,
CancelIntent = 2,
LockIntentForSolving = 3,
SolveIntent = 4,
CancelIntentLock = 5,
}
Next Steps