Token Buyer

This project is under development by Nouns DAO. It's inspired by YFI Buyer.

Technical spec

The purpose of this project is to allow the DAO to pay with ERC20 tokens (e.g. stablecoins) in proposals. It's not straightforward for a DAO to swap from ETH to an ERC20 without getting bad price due to sandwich bots pushing the slippage to the max. It also allows the DAO to not necessarily hold a large position of the ERC20 to facilitate the payments. Instead, the swaps happens on a need basis.

When the DAO wants to pay with tokens, it can do a proposal a tx that calls Payer.sendOrRegisterDebt(account, amount). That will transfer tokens if Payer has available balance, and otherwise will register a debt entry for that account and amount.

The TokenBuyer contract gets funded with ETH by the DAO, and offers anyone to swap ETH for tokens. The price is set by an external oracle (e.g. chainlink). There's an incentive to swap with TokenBuyer when the oracle price is lagging and favorable to other exchanges. Once a swap has happened, any outstanding debt is paid.

Contracts

• TokenBuyer

  • Gets funded with ETH (e.g. by the DAO treasury)
  • Allows anyone to swap ERC20 tokens (e.g. USDC) for ETH
  • ERC20 tokens are sent to Payer
  • The price is set according to an oracle (PriceFeed)
  • Limits the amount of ERC20 it will buy according to the amount of debt in Payer + some buffer
  • Once a swap happens, attempt to pay any outstanding debt in Payer by calling Payer.payBackDebt

• Payer

  • Receives ERC20 tokens from TokenBuyer
  • Can be asked to send the tokens to an address by the owner (e.g. the DAO)
  • If there aren't enough tokens, registers a debt entry, and pays it out in FIFO order when more tokens are available

• PriceFeed

  • Returns a price for ETH/token from an external oracle (e.g. chainlink)

Tests

Since we're running some tests with a mainnet fork, to get the best trace include your Etherscan API key when running tests:

forge test --etherscan-api-key <your api key here>

If you're ok with a less-readable trace simply run:

forge test

To run all tests except mainnet forking tests:

forge test --nmc '.*Fork.*' -vvv

Deploy to testnet

forge script script/DeployUSDC.s.sol:DeployUSDCGoerli --broadcast --verify -vvvvv --chain-id 5 --rpc-url <GOERLI_RPC> --keystores <KEYSTORE> --sender <DEPLOYER_ADDRESS>

Deploy to mainnet

forge script script/DeployUSDC.s.sol:DeployUSDCMainnet --broadcast --verify -vvvvv --chain-id 1 --rpc-url $MAINNET_RPC --sender $DEPLOYER_MAINNET -i 1

Latest deployment

Sepolia

Contract	Address
TokenBuyer	0x821176470cFeF1dB78F1e2dbae136f73c36ddd48
Payer	0x5a2A0951C6b3479DBEe1D5909Aac7B325d300D94
PriceFeed	0xaa9AEE18f521E9dC9842a67963Bdb7689bb5D54b

Goerli

Contract	Address
TokenBuyer	0x61Ec4584c5B5eBaaD9f21Aac491fBB5B2ff30779
Payer	0xD4A3bf1dF54699E63A2ef7F490E8E22b27B945f0
PriceFeed	0x60C80ee511fce9631dce795C48D60Bbf6922e3e9

Mainnet

Contract	Address
TokenBuyer	0x4f2aCdc74f6941390d9b1804faBc3E780388cfe5
Payer	0xd97Bcd9f47cEe35c0a9ec1dc40C1269afc9E8E1D
PriceFeed	0x05e651Bc3a7f7B7640cAD61dC383ca28Ae000cce