Cross-Chain Rebase Token

A Foundry-based Solidity project that mints yield-bearing rebase tokens for ETH deposits and bridges them across chains with Chainlink CCIP while preserving each user's accrued-interest rate.

Table of Contents

• Overview
• How It Works
• Tech Stack
• Repository Layout
• Getting Started
• Environment Variables
• Commands
• CI and Releases

Overview

This protocol lets users deposit ETH into a vault and receive a rebase token that represents their underlying position plus linearly accrued interest over time.

The design centers on three ideas:

• Vault accepts ETH deposits and redemptions.
• RebaseToken tracks principal balances and lazily realizes accrued interest during user actions.
• RebaseTokenPool integrates Chainlink CCIP so balances can move cross-chain without losing the user's assigned interest rate.

How It Works

1. A user deposits ETH into Vault.
2. The vault mints RebaseToken to the depositor using the protocol's current global interest rate.
3. Each account keeps its own interest rate snapshot from the moment it enters the system.
4. The token balance grows linearly over time and accrued interest is minted when the user interacts with the token.
5. When tokens are bridged with CCIP, the pool encodes the user's interest rate in the cross-chain payload and restores it on the destination chain.

Tech Stack

• Solidity 0.8.24
• Foundry for build, test, scripting, and formatting
• OpenZeppelin Contracts for ERC-20, ownership, and access control primitives
• Chainlink CCIP and CCIPLocalSimulatorFork for cross-chain token pool logic and fork-based testing
• GitHub Actions for CI and automated releases with semantic-release

Repository Layout

• src/RebaseToken.sol: Core rebase token with user-specific interest rates and lazy interest realization
• src/Vault.sol: ETH vault that mints and redeems the rebase token
• src/RebaseTokenPool.sol: Chainlink CCIP token pool used to burn, mint, and preserve interest-rate state across chains
• src/interfaces/IRebaseToken.sol: Shared interface used by the vault and pool
• test/RebaseToken.t.sol: Unit tests for deposit, redeem, transfer, and interest-rate behavior
• test/CrossChain.t.sol: Fork-based cross-chain bridging tests using Sepolia and Arbitrum Sepolia RPC endpoints
• script/Deployer.s.sol: Deployment helpers for token, pool, vault, and token admin configuration
• script/ConfigurePool.s.sol: Script for applying remote chain pool configuration
• script/BridgeTokens.s.sol: Script for sending tokens through the CCIP router

Getting Started

Prerequisites

• Foundry
• Git with submodule support

Install Dependencies

Clone with submodules:

git clone --recurse-submodules git@github.com:Axeloooo/Cross-Chain-Rebase-Token.git

If the repository is already cloned:

git submodule update --init --recursive

Environment Variables

Cross-chain tests use live RPC endpoints for Sepolia and Arbitrum Sepolia forks:

export SEPOLIA_RPC_URL="<your-sepolia-rpc-url>"
export ARBITRUM_SEPOLIA_RPC_URL="<your-arbitrum-sepolia-rpc-url>"

When broadcasting deployment scripts, provide the usual Foundry CLI flags such as --rpc-url, --private-key, or --account.

Commands

Build and Format

forge build
forge fmt
forge fmt --check

Run Tests

Run the full test suite:

forge test -vvv

Run only unit tests:

forge test --match-path test/RebaseToken.t.sol -vvv

Run the cross-chain fork test:

SEPOLIA_RPC_URL="$SEPOLIA_RPC_URL" \
ARBITRUM_SEPOLIA_RPC_URL="$ARBITRUM_SEPOLIA_RPC_URL" \
forge test --match-path test/CrossChain.t.sol -vvv

Run Scripts

Deploy token and pool:

forge script script/Deployer.s.sol:TokenAndPoolDeployer --rpc-url "$SEPOLIA_RPC_URL" --broadcast

Deploy the vault:

forge script script/Deployer.s.sol:VaultDeployer --rpc-url "$SEPOLIA_RPC_URL" --broadcast --sig "run(address)" <REBASE_TOKEN_ADDRESS>

Configure a remote pool:

forge script script/ConfigurePool.s.sol:ConfigurePoolScript --rpc-url "$SEPOLIA_RPC_URL" --broadcast

Bridge tokens with CCIP:

forge script script/BridgeTokens.s.sol:BridgeTokenScript --rpc-url "$SEPOLIA_RPC_URL" --broadcast

CI and Releases

• .github/workflows/test.yml runs formatting checks, builds the contracts, and executes tests in CI.
• .github/workflows/release.yml runs semantic-release on pushes to main.
• The release workflow now fetches full git history and tags so semantic-release can compute versions from the complete commit and tag graph.