Supercharging ERC-4626 tokens on Arbitrum:

1. Underlying assets & value accrual live on L1 (mainnet)

   1. L1 can offer diverse and robust yield opportunities

2. Tokens are canonically L2 (Arbitrum) for affordable utilization:

   1. Deposit into the vaults from L2
   2. Transfer, trade, and exchange the tokens on L2
   3. Exchange rate is correctly observable on L2 (with some latency)
   4. Ideally use vaults in composable systems -- i.e. lending (?)

This repo is intended to be an educational application of Arbitrum's cross-chain messaging (L1 <--> L2); you should reference their tutorial as an additional example

Main difference is:

1. This repo uses on foundry (forge + cast) instead of javascript

2. This repo offers clearer distinction between L1-to-L2 and L2-to-L1 messaging. 4626 Vaults also offer of a real world use-case of cross-chain messaging.

Note: this example does not contain mechanisms to guarantee ERC-4626 redemption liquidity. Proceed with caution when using in production

Cross-chain messaging is handled at the node level (nitro nodes know to communicate to a corresponding L1 node), the core messaging logic cannot be tested with forge test

Instead, run Arbitrum local dev node(s) (nitro + geth) to execute forge scripts against the two nodes

Run L1 + L2 local nodes with Docker: https://developer.arbitrum.io/node-running/local-dev-node

1. Messaging occurs over the course of a few blocks, so testing the functionality will occur over multiple scripts. See scripts/ and /scripts/local.sh

2. L2-to-L1 messages takes 7 days (on mainnet / production)

   • Modify the confirmation time of our local nodes to be 1 block instead scripts/local.sh

     # Set the challenge period to be 1 block for testing L2 --> L1 messages
     # (normally its a week!)
     cast send 0x65a59d67da8e710ef9a01eca37f83f84aedec416 "setConfirmPeriodBlocks(uint64)" 1 \
         --rpc-url $mainnetRPC \
         --private-key $rollupPK

3. Custom opcodes by Arbitrum (i.e. arbsys.withdrawEth()) are not supported within forge scripts. Contract functions which send messages from L2 to L1 are handled with cast

   scripts/local.sh

   # Simulating L2 --> L1 message (sweepToL1)
   # Need to use cast since arbsys.withdrawEth uses a custom opcode
   # which foundry EVM does not recognize
   cast send $ARB_VAULT "sweepToL1()" \
       --rpc-url $arbitrumRPC \
       --private-key $arbPK

Run Cross-chain messaging tests & integration

# start the L1 geth and L2 nitro dev nodes
# (in the offchainlabs/nitro repository)
./test-node.bash

# Execute forge scripts & cast calls, from the repository root
# Non-blocking script, so you should monitor the output for errors
./scripts/local.sh

Run solidity/vault tests

forge test

You will need a copy of Foundry installed before proceeding. See the installation guide for details.

git clone https://github.com/saucepoint/super-ERC4626-example
cd super-ERC4626-example

forge install

# Recommended to use node v16 to install arbitrum dependencies
npm install

# install jq on Linux
sudo apt install jq

# install jq on Mac
brew install jq