OctoIntents

🔍 Project Description

Unifying EVM & BTC using Cross-Chain Intents and Dutch Auctions

This project introduces a trust-minimized cross-chain interoperability framework that unifies the Bitcoin and Ethereum ecosystems through cross-chain intents, Hyperlane messaging, ERC-7683, and a Dutch auction-based solver mechanism. It enables users to seamlessly bridge tokens between heterogeneous chains (such as Ethereum Sepolia, Rootstock, and Citrea testnets), while optimizing for capital efficiency, decentralization, and settlement speed.

At its core, users express what they want done (not how) by submitting intents, which solvers then compete to fulfill via on-chain Dutch auctions-based selection mechanism.

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🔁 How It Works – End-to-End Flow

1. User Opens Intent (Deposits Tokens to Escrow on Chain C1)
   A user (e.g., Alice) deposits tokens into an escrow contract on Chain C1 (e.g., Ethereum Sepolia). This deposit triggers the creation of a formal intent, which describes Alice’s desired action—typically, to receive the equivalent value of tokens on Chain C2.

2. Intent Message Dispatched via Hyperlane
   The intent metadata is securely dispatched from Chain C1 to Chain C2 using Hyperlane Mailbox, a modular interchain messaging protocol that ensures trustless communication.

3. Dutch Auction Starts on Chain C2
   Upon receipt, Chain C2 initiates a Dutch auction representing the open intent. The auction begins with a high reward (price) and linearly decreases over time until a solver accepts the task.

4. Solver Selection via Dutch Auction
   Multiple solvers monitor Chain C2 for open intents. The first solver to accept the current price wins the auction, locking in their right to fulfill the intent.

5. Solver Executes and Fills Intent
   The winning solver delivers the required tokens to Alice on Chain C2, effectively fulfilling the user’s request.

6. Escrow Settlement on Chain C1
   Once fulfillment is verified (using Hyperlane messages), the solver can claim Alice’s originally escrowed tokens from Chain C1—completing the settlement process.

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🧠 Why This Matters

This approach solves key limitations of traditional bridging and settlement mechanisms:

❌ The Problem: Slow and Centralized Settlements

• Hours 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.

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✅ The Solution: Intents + Dutch Auctions + Hyperlane

• Trustless 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.

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📊 Capital Efficiency: Why Dutch Auctions Matter

Traditional bridges suffer from inefficiencies due to long settlement cycles and liquidity lock-up. This system radically improves capital efficiency, making bridging more sustainable and accessible.

According to DeFiLlama (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 every 20 seconds on Ethereum
• 1 transaction every 40 seconds on rollups

Now consider capital locked up for solvers:

• If paid every 60 minutes, a solver must maintain $800K in inventory across 3 chains.
• If paid every 1 minute, they only need ~$13,500.

This is a 60x improvement in capital efficiency.

By enabling faster solver settlement through Dutch auction-based intents and instant on-chain verification, the system reduces the opportunity cost, thereby lowering user fees and increasing solver participation.

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🌐 Deployed Networks

• Ethereum Sepolia Testnet
• Rootstock Testnet
• Citrea Testnet

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🧩 Built With:

• ERC-7683 – Standard for cross-chain intents
• Hyperlane – Interchain messaging layer
• Dutch Auction Contracts – For solver selection and pricing
• Escrow Mechanism – For atomic intent lifecycle across chains

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This project brings us closer to a modular, unified cross-chain future, bridging the liquidity, programmability, and users of Bitcoin and Ethereum ecosystems through intent-based interoperability—efficient, decentralized, and scalable.

This project is a modular cross-chain settlement framework that unifies EVM and Bitcoin ecosystems using ERC-7683 intents, Hyperlane-powered messaging, and a Dutch auction-based solver selection mechanism. It enables capital-efficient, permissionless, and transparent bridging between chains like Ethereum Sepolia, Rootstock, and Citrea.

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🧱 Core Architecture

1. Intent Creation & Escrow (Chain C1)

The bridging process begins when a user deposits tokens into an ERC-7683-compliant escrow contract on Chain C1.
This deposit acts as a cross-chain intent, encoding:

• Source and destination chains
• Token type and amount
• Minimum acceptable output
• Auction and settlement configuration

The escrow holds user funds while awaiting settlement.

2. Cross-Chain Intent Dispatch with Hyperlane Mailbox

The intent message is dispatched to Chain C2 using the Hyperlane Mailbox and Hyperlane Messenger, forming a part of the Open Intents Framework (OIF).
This enables secure and programmable message passing between 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 a custom Dutch auction to 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 solvers
• The price decreases linearly over time
• The first solver to accept the current price wins the auction
• The auction ends if no solver accepts within the defined time window

This mechanism ensures capital-efficient, decentralized, and transparent solver selection, preventing centralization and maximizing value returned to the user.

4. Solver Settlement & Fulfillment

The winning solver:

• Transfers the output tokens to the user on Chain C2
• Fulfills the intent by submitting proof (or interaction) back to the escrow contract on Chain C1

The escrow verifies the fulfillment and releases the user’s tokens to the solver, finalizing the swap.

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🛠️ 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 |

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🤝 Partner Integrations

• Hyperlane enabled cross-chain messaging through its Mailbox contracts and Messenger pattern. We integrated Hyperlane into our intent settlement logic.
• Citrea offered a ZK-rollup on Bitcoin, which allowed us to explore native BTC-EVM bridging with intents.
• Rootstock brought smart contract programmability to Bitcoin’s security layer, enabling native escrow and solver flows on BTC-linked networks.

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⚙️ Hacky/Notable Engineering Wins

• Unique Dutch Auction-Based Solver Selection:
  Our custom-designed solver auction contract deploys auctions per-intent, where price decays over time until accepted by a solver. This reduces solver hoarding and introduces fair, dynamic participation. It brings price 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, we manually deployed the full suite of Hyperlane core contracts to bootstrap message routing between Sepolia and Rootstock.

• Manual Message Relaying to Trigger Dutch Auctions:
  We used the Hyperlane CLI to manually relay messages from Sepolia to Rootstock in the absence of an automated relayer. This confirmed that intent dispatch and auction triggering could work end-to-end even in low-infra testnet environments.

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📈 Capital Efficiency Advantage

According to a capital analysis inspired by DeFiLlama's stats from Feb 12, 2025:

• Across processed ~$19.1M in daily bridging volume with 9507 transactions
• Assuming one TX every 20–40 seconds, a solver would need ~$800K inventory if paid hourly
• With our minute-level settlement capability, a solver only needs ~$13.5K inventory across chains
  👉 This results in a 60x improvement in capital efficiency

By reducing the capital lockup for solvers, we drastically reduce costs and fees for users, while expanding decentralized access to solver roles.

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🧩 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 |

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🚀 Summary

We’ve built a protocol that combines ERC-7683 intents, Dutch auction-based solver selection, and Hyperlane messaging into a trust-minimized framework for cross-chain settlement.
It unlocks fast, transparent, and capital-efficient bridging across Ethereum, Rootstock, Citrea, and eventually Bitcoin.