Omnichain Governance Executor extends existing governance protocols (e.g., Compound GovernorBravo) with Layer Zero omnichain messaging protocol to enable cross-chain proposal execution. The two main contracts are OmnichainProposalSender and OmnichainGovernanceExecutor.

OmnichainProposalSender allows sending proposal actions to other chains for execution. It has to be deployed on the main chain where voting is taking place (e.g., Ethereum). When used with GovernorBravo the owner of the OmnichainProposalSender must be set to Timelock contract.

OmnichainGovernanceExecutor executes the proposal actions on other chains. It must be deployed on each chain that needs to support the remote proposal execution. OmnichainGovernanceExecutor contract derives from NonBlockingLzApp and provides non-blocking message delivery, meaning failed messages won't block the message queue from the main chain. For the blocking behavior inherit the contract from LzApp.

• Clone the repository
• run yarn

yarn test

Run the full suite of unit tests.

yarn coverage

Get the coverage report.

1. Refer to LayerZero gitbook for LayerZero Endpoint addresses and chain ids.
2. Deploy OmnichainProposalSender on the main chain (e.g. Ethereum) where voting is taking place.
3. Deploy OmnichainGovernanceExecutor on each chain that needs to support remote proposal execution (e.g., Polygon, Arbitrum, Optimism, etc).
4. Call setTrustedRemoteAddress in OmnichainProposalSender for each remote chain providing LayerZero chain id and an address of OmnichainGovernanceExecutor contract on that chain.
5. Call setTrustedRemoteAddress in OmnichainGovernanceExecutor on each remote chain proving the main chain id and an address of OmnichainProposalSender
6. Optionally set a custom configuration (e.g. Oracle, Relayer, number of confirmations) by calling setConfig in OmnichainProposalSender and all OmnichainGovernanceExecutor.
7. Transfer ownership of OmnichainProposalSender to a contract that executes a proposal. For GovernorBravo it's Timelock contract.
8. Transfer ownership of each OmnichainGovernanceExecutor to itself or a Timelock contract.

For each remote chain do the following:

1. Encode the proposal actions that needs to be executed as follows payload = abi.encode(targets, values, signatures, calldatas)
2. Call estimateFees in OmnichainProposalSender passing the remote chain id, the payload constructed in the previous step and adapter parameters. Adapter parameters allows specifying the amount of gas required on destination to execute the proposal. We recommend testing the execution logic on the destination chain to determine the required amount. To learn more about adapter parameters refer to LayerZero gitbook
3. Create a proposal action as follows:

• target an address of OmnichainProposalSender contract
• value LayerZero fee for message delivery. Generally it should be equal to nativeFee obtained in the previous step by calling estimateFees. However, since there is a significant time period between the proposal creation and execution, the fees estimation might be inaccurate and we're highly recommend increasing the amount of fees passed (e.g., nativeFee.mul(2)). Unused amount will be refunded to the address that initiated the proposal execution on the main chain (tx.origin)
• signature the signature of execute function in OmnichainProposalSender contract ("execute(uint16,bytes,bytes)")
• calldata the encoded parameters of execute function in OmnichainProposalSender (abi.encode(remoteExecutorChainId, payload, adapterParams))

4. Pass the values as part of the corresponding arrays in propose function of GovernorBravoDelegate contract

When Timelock contract executes the proposal it calls execute function in OmnichainProposalSender which sends the proposal actions to the remote chain.

Sending a message might fail on the main chain the calling execute. The most common reason for this is insufficient fees supplied. To retry a failed message do the following:

1. Find StorePayload event that was emitted.
2. If the reason indicates insufficient fees, call estimateFees again
3. Call retryExecute in OmnichainProposalSender supplying the parameters from the event and the fees obtained in the previous step