GoodDollar OFT - LayerZero Cross-Chain Bridge

[blueogin]

Motivation

Implement LayerZero OFT (Omnichain Fungible Token) adapter for GoodDollar to enable secure, efficient cross-chain token transfers between networks. This replaces legacy bridge solutions with a modern, standardized approach that maintains token supply integrity across chains through mint/burn mechanics.

Details

• Develop GoodDollarMinterBurner contract which has minter role for GoodDollar (DAO-upgradeable)
• Develop GoodDollarOFTAdapter contract which calls & routes cross-chain token transfer (non-upgradeable)
• Make GoodDollarMinterBurner pausable to effectively halt bridging when needed.
• Evaluate whether a transfer limit is required for cross-chain bridging.
• Update deployment.json with contract addresses
• Add XDC & CELO LayerZero endpoint configuration
• Grant MINTER_ROLE to GoodDollarMinterBurner
• Set OFT adapter as operator on MinterBurner via DAO
• Create bridge script
• Test it on CELO and XDC

[blueogin]

@sirpy
After research, I think developing 2 contracts - GoodDollarMinterBurner and GoodDollarOFTAdapter is enough for our project's need.

GoodDollarMinterBurner is required because MintBurnOFTAdapter from LZ expects an IMintableBurnable interface for minting and burning and GoodDollar does not implement the interface.
Also we can add our logic simply to the GoodDollarMinterBurner like pausing and trading limit.
However, we should manage GoodDollarMinterBurner carefully, since it holds the MINTER_ROLE for the GoodDollar token.

Here is the cross-chain transfer flow.

Sending

1. User approves OFT Adapter to spend tokens
   └─> token.approve(oftAdapter, amount)

2. User calls OFT Adapter's send() function
   └─> oftAdapter.send(destination, amount, ...)

3. OFT Adapter internally:
   a. Transfers tokens from user to itself
   b. Calls MinterBurner.burn(user, amount)
   c. MinterBurner calls token.burnFrom(user, amount)
   d. Tokens are burned on source chain

4. OFT Adapter sends LayerZero message to destination chain
   └─> Contains: recipient address, amount, etc.

Receiving

1. LayerZero delivers message to OFT Adapter on destination

2. OFT Adapter's lzReceive() is called:
   a. Validates the message (from trusted source)
   b. Calls MinterBurner.mint(recipient, amount)
   c. MinterBurner calls token.mint(recipient, amount)
   d. Tokens are minted on destination chain

3. Recipient receives tokens on destination chain