Escrow (Trusted Token Transfer)

src/Escrow.sol implements a small, trusted escrow used to swap Flying Tulip (FT) tokens for an ERC20 denomination token.

Summary

• Owner (Flying Tulip) funds the escrow with FT tokens.
• Recipient transfers the denomination token into the escrow.
• Once the escrow has received at least amountDenom denomination tokens (tracked even if the owner has already withdrawn them), the recipient can withdraw FT.

This design assumes a trusted flow: there is no price enforcement, timeouts, or partial-fill logic.

Key Details

• FT token address is fixed (same on every network): Escrow.FT() is hard-coded to 0x5DD1A7A369e8273371d2DBf9d83356057088082c.
• The escrow does not have deposit functions; funding is done via standard ERC20 transfer to the escrow address.
• Transfers use OpenZeppelin SafeERC20 to safely handle non-standard ERC20 return values.
• withdrawnAmountDenom tracks denomination tokens already withdrawn by the owner so the recipient can still withdraw FT after payment is received.

Contract Interface

• withdraw(address token, uint256 amount) (owner only): withdraw any token except the denomination token.
• withdrawDenom(uint256 amount) (owner only): withdraw denomination tokens and increment withdrawnAmountDenom.
• withdrawFT(uint256 amount) (recipient only): withdraw FT once denomination.balanceOf(escrow) + withdrawnAmountDenom >= amountDenom.

Development

Install

git submodule update --init --recursive

Build

forge build

Test

forge test -vvv

Coverage

forge coverage

Note: src/Escrow.sol is excluded from forge fmt to preserve the audited source exactly.

Deploy

Deployment uses script/DeployEscrow.s.sol:DeployEscrowScript.

Environment variables read by the script:

• PRIVATE_KEY (deployer key)
• ESCROW_OWNER
• ESCROW_RECIPIENT
• ESCROW_DENOMINATION
• ESCROW_AMOUNT_DENOM

Example:

export PRIVATE_KEY=...
export ESCROW_OWNER=0x...
export ESCROW_RECIPIENT=0x...
export ESCROW_DENOMINATION=0x...
export ESCROW_AMOUNT_DENOM=100000000000000000000

forge script script/DeployEscrow.s.sol:DeployEscrowScript \
  --rpc-url $RPC_URL \
  --broadcast