Synapse Intent Network

Synapse Intent Network (SIN) is an RFQ (Request-For-Quote) based intent centric bridging system that connects bridging users to a network of relayers.

These relayers compete to provide the optimal bridge execution (eg: the best price) for the user's specific request.

Request-For-Quote End-to-End Flow

Order	User inputs their desired order into a bridge interface.
Quote	Quotes from Relayers are evaluated and resolved to the optimal choice to match the user's input. The resolved quote is used to construct a bridge transaction for the user to sign.
Request	User signs and submits the bridge transaction on-chain. Their assets are deposited into a Bridge contract on the originChain.
Relay	A Relayer completes the user's bridge on the destChain by delivering the user's desired funds. At this point, the bridge is complete from the user's perspective.
Prove	The Relayer submits an optimistic proof of their completed relay to the originChain.
Guard	After a proof is asserted for each bridge, a brief optimistic dispute period is initiated. During this period, Guard entities will verify that the proof is valid and accurate.
Claim	After the dispute period has passed, the Relayer may claim the user's originally deposited funds. This reimburses the Relayer for the funds which they delivered in the earlier relay step.

Entities

Users (Permissionless Role)

Uses a bridge interface to submit their intent to the RFQ system for a quote, and then to the chain for fulfillment.

Quoters (Permissioned Role)

Posts Passive and/or Active Quotes via the Quoter API to be matched against user bridge inputs.

Note: In practice, each participating Quoter typically acts as their own Relayer and Prover.

Relayers (Permissionless Role)

Observes bridge deposits and submits relay transactions to fulfill them.

Also submits claim transactions to be reimbursed for their relays.

Note: In practice, each participating Relayer typically acts as their own Quoter and Prover.

Provers (Permissioned Role)

Observes relays and submits prove transactions to initiate relayer reimbursements.

Note: In practice, each participating Prover typically acts as their own Quoter and Relayer.

Guards (Permissioned Role)

Validates proofs during the Dispute Period and submits dispute transactions for any discrepancies found.

Currently, Synapse itself is the sole Guard operator of the Synapse Intent Network (SIN) system.

Cancelers (Permissioned Role)

Able to manually pre-emptively cancel bridge requests which have been deposited, have not yet been relayed, and are past their relay deadline.

Currently, Synapse itself is the sole Canceler operator of the Synapse Intent Network (SIN) system.

Note: Incomplete bridge requests can also be canceled permissionlessly (without any involvement from a Canceler) after a longer cancellation window has passed.

Architecture

Quoter API

The RESTful Quoter API allows Quoters to post Passive and/or Active Quotes. These quotes are then used to create transactions for Users to sign and submit.

FastBridge Smart Contracts

Synapse FastBridge contracts facilitate and enforce all of the on-chain functionality and security of the system.

This includes the bridge, deposit, escrow, and eventual release of user funds on the origin chain.

Associated relay, prove, claim, dispute, and cancel actions are also facilitated by FastBridge contracts.

Additionally, the FastBridge contracts manage all relevant permissions and on-chain configuration settings of the system.

FastBridge contracts will be deployed on all supported chains.

Flow Summary

Quoting

A User inputs their desired bridge information into an bridge interface such as Synapse.

Quotes to complete the bridge are collected from [Quoters]. The best of these is resolved and presented to the user as a bridge transaction to sign & submit on-chain.

Bridging

Once the User has signed and submitted their deposit on-chain via a bridge transaction, the bridging funds will be transferred to a FastBridge contract and held in escrow.

Relaying

Relayers who observe the bridge deposit event can permissionlessly complete the bridge by calling relay on the FastBridge contract of the destination chain. Typically the Relayer is the same as the Quoter.

This will transfer the bridge destination funds from the Relayer to the User, with FastBridge acting as intermediary.

At this point, the process is complete from the User's perspective. However, the Relayer needs to be reimbursed for the funds they delivered.

Proving

After the relay, a Prover (typically also the Relayer) will submit a prove transaction with the relay transaction's details to the origin chain's FastBridge contract.

This asserts that the relay for the bridge was completed according to the specifications of the User, and that the Relayer can rightfully claim the escrowed funds.

A Dispute Period begins for the transaction before the claim can occur.

Dispute Period

During the Dispute Period, Guard entities will verify that the proof's assertion is accurate.

IE: They will confirm that the relay being asserted was completed exactly as specified by the user.

If any discrepancies are found, the guards will dispute the proof

Claiming

Once the Dispute Period has passed without incident, a claim transaction can be executed by the Relayer on the origin chain.

This will release the deposit funds from escrow and deliver them to the rightful Relayer as a reimbursement for the liquidity they provided on the relay.