OctoIntents

Problem Statement

🔍 Project DescriptionUnifying EVM & BTC using Cross-Chain Intents and Dutch AuctionsThis project introduces a trust-minimized cross-chain interoperability framework that unifies the Bitcoin and Ethereum ecosystems throughcross-chain intents,Hyperlane messaging,ERC-7683, and aDutch auction-based solver mechanism. It enables users to seamlessly bridge tokens between heterogeneous chains (such as Ethereum Sepolia, Rootstock, and Citrea testnets), while optimizing forcapital efficiency, decentralization, and settlement speed.At its core, users expresswhatthey want done (nothow) by submittingintents, which solvers then compete to fulfill viaon-chain Dutch auctions-based selection mechanism.🔁 How It Works – End-to-End FlowUser Opens Intent (Deposits Tokens to Escrow on Chain C1)A user (e.g., Alice) deposits tokens into anescrow contractonChain C1(e.g., Ethereum Sepolia). This deposit triggers the creation of a formalintent, which describes Alice’s desired action—typically, to receive the equivalent value of tokens onChain C2.Intent Message Dispatched via HyperlaneThe intent metadata is securely dispatched from Chain C1 to Chain C2 usingHyperlane Mailbox, a modular interchain messaging protocol that ensures trustless communication.Dutch Auction Starts on Chain C2Upon receipt, Chain C2 initiates aDutch auctionrepresenting the open intent. The auction begins with a high reward (price) and linearlydecreases over timeuntil a solver accepts the task.Solver Selection via Dutch AuctionMultiple solvers monitor Chain C2 for open intents. The first solver to accept the current pricewins the auction, locking in their right to fulfill the intent.Solver Executes and Fills IntentThe winning solverdelivers the required tokens to Alice on Chain C2, effectively fulfilling the user’s request.Escrow Settlement on Chain C1Once fulfillment is verified (using Hyperlane messages), the solver canclaim Alice’s originally escrowed tokensfrom Chain C1—completing thesettlement process.🧠 Why This MattersThis approach solves key limitations of traditional bridging and settlement mechanisms:❌ The Problem: Slow and Centralized SettlementsHours of Waiting– Solvers often wait hours to receive funds post-settlement.Limited Access– Only a few privileged actors can act as relayers/solvers.Centralized Control– Trust assumptions remain high, and systems lack transparency.✅ The Solution: Intents + Dutch Auctions + HyperlaneTrustless Fulfillment– Settlement is enforced via escrow and cross-chain proofs.Decentralized Solver Market– Anyone can compete to fulfill intents using open auctions.Faster Execution– Settlement is near-instant post-fulfillment verification.📊 Capital Efficiency: Why Dutch Auctions MatterTraditional bridges suffer from inefficiencies due to long settlement cycles and liquidity lock-up. This system radically improvescapital efficiency, making bridging more sustainable and accessible.According toDeFiLlama (Feb 12, 2025), Across facilitated ~$19.1M in volume and ~9500 bridge transactions in 24h across Ethereum, Optimism, and Arbitrum. This translates to:1 transaction every20 seconds on Ethereum1 transaction every40 seconds on rollupsNow consider capital locked up for solvers:If paidevery 60 minutes, a solver must maintain$800K in inventoryacross 3 chains.If paidevery 1 minute, they only need~$13,500.This is a60x improvement in capital efficiency.By enabling faster solver settlement through Dutch auction-based intents and instant on-chain verification, the systemreduces the opportunity cost, thereby lowering user fees and increasing solver participation.🌐 Deployed NetworksEthereum Sepolia TestnetRootstock TestnetCitrea Testnet🧩 Built With:ERC-7683– Standard for cross-chain intentsHyperlane– Interchain messaging layerDutch Auction Contracts– For solver selection and pricingEscrow Mechanism– For atomic intent lifecycle across chainsThis project brings us closer to amodular, unified cross-chain future, bridging the liquidity, programmability, and users of Bitcoin and Ethereum ecosystems throughintent-based interoperability—efficient, decentralized, and scalable.

Solution

This project is a modular cross-chain settlement framework that unifies EVM and Bitcoin ecosystems usingERC-7683 intents,Hyperlane-powered messaging, and aDutch auction-based solver selection mechanism. It enables capital-efficient, permissionless, and transparent bridging between chains likeEthereum Sepolia,Rootstock, andCitrea.🧱 Core Architecture1.Intent Creation & Escrow (Chain C1)The bridging process begins when a user deposits tokens into anERC-7683-compliant escrow contracton Chain C1.This deposit acts as across-chain intent, encoding:Source and destination chainsToken type and amountMinimum acceptable outputAuction and settlement configurationThe escrow holds user funds while awaiting settlement.2.Cross-Chain Intent Dispatch with Hyperlane MailboxThe intent message is dispatched to Chain C2 using theHyperlane MailboxandHyperlane Messenger, forming a part of theOpen Intents Framework (OIF).This enablessecure and programmable message passingbetween heterogeneous chains. Upon receipt, the destination chain contract parses the message and launches a solver auction.3.Custom Dutch Auction-Based Solver Selection (Chain C2)Once an intent is received, our system initiates acustom Dutch auctionto select the solver. Unlike static pricing or round-robin relayers, our approach dynamically discovers the best price through open competition:Auctions begin at a high reward for solversThe pricedecreases linearly over timeThefirst solver to accept the current pricewins the auctionThe auction ends if no solver accepts within the defined time windowThis mechanism ensurescapital-efficient, decentralized, and transparent solver selection, preventing centralization and maximizing value returned to the user.4.Solver Settlement & FulfillmentThe winning solver:Transfers the output tokens to the user on Chain C2Fulfills the intent by submitting proof (or interaction) back to the escrow contract on Chain C1The escrow verifies the fulfillment andreleases the user’s tokensto the solver, finalizing the swap.🛠️ Technologies & Tooling Used| Tech/Tool | Purpose | |------------------------|-------------------------------------------------| |Solidity| Smart contracts for intents, auctions, and escrow | |ERC-7683| Standard for intents and settlement interfaces | |Hyperlane| Cross-chain messaging (Messenger + Mailbox) | |Open Intents Framework (OIF)| Intent modeling and routing | |Rootstock & Citrea| EVM-compatible Bitcoin networks for BTC bridging | |Foundry| Development, scripting, and testing | |Ethers.js| JS SDK for on-chain interactions and frontend integration |🤝 Partner IntegrationsHyperlaneenabled cross-chain messaging through itsMailboxcontracts andMessenger pattern. We integrated Hyperlane into our intent settlement logic.Citreaoffered a ZK-rollup on Bitcoin, which allowed us to explore native BTC-EVM bridging with intents.Rootstockbrought smart contract programmability to Bitcoin’s security layer, enabling native escrow and solver flows on BTC-linked networks.⚙️ Hacky/Notable Engineering WinsUnique Dutch Auction-Based Solver Selection:Our custom-designed solver auction contract deploys auctionsper-intent, where price decays over time until accepted by a solver. This reduces solver hoarding and introduces fair, dynamic participation. It bringsprice discovery into the settlement process itself, unlike most bridging protocols that preselect relayers or quote fixed prices.Deployed Hyperlane on Rootstock Testnet:Since Hyperlane wasn't already present on Rootstock Testnet, wemanually deployed the full suite of Hyperlane core contractsto bootstrap message routing between Sepolia and Rootstock.Manual Message Relaying to Trigger Dutch Auctions:We used theHyperlane CLIto manually relay messages from Sepolia to Rootstock in the absence of an automated relayer. This confirmed that intent dispatch and auction triggering could workend-to-end even in low-infra testnet environments.📈 Capital Efficiency AdvantageAccording to a capital analysis inspired by DeFiLlama's stats from Feb 12, 2025:Across processed ~$19.1M in daily bridging volume with 9507 transactionsAssuming one TX every 20–40 seconds, a solver would need ~$800K inventoryif paid hourlyWith ourminute-level settlement capability, a solver only needs ~$13.5K inventory across chains👉 This results in a60x improvement in capital efficiencyBy reducing the capital lockup for solvers, we drastically reduce costs andfees for users, while expandingdecentralized access to solver roles.🧩 Solving the Status Quo| Problem | Our Solution | |------------------------|--------------------------------------------------| |Slow Settlements| Real-time solver auctions + fast fulfillment | |Centralized Solvers| Open auction-based selection mechanism | |Capital Intensive| High-frequency payouts → low inventory needs | |Opaque Systems| Transparent, on-chain auction & intent lifecycle |🚀 SummaryWe’ve built a protocol that combinesERC-7683 intents,Dutch auction-based solver selection, andHyperlane messaginginto a trust-minimized framework for cross-chain settlement.It unlocks fast, transparent, and capital-efficient bridging across Ethereum, Rootstock, Citrea, and eventually Bitcoin.