Modular Multichain Governance

Modular Multichain Governance is a system to pass messages from Ethereum L1 to L2's and other L1's based on Uniswap governance decisions.

We define a SenderHub on Ethereum and a ReceiverHub on remote chains (L2's or other L1's), which are used to abstract underlying bridge details for sending messages. The bridge details are abstracted by Encoder and Decoder modules.

Sending Messages

The SenderHub assigns an Encoder module for a given remote chain (by its chainId). When the SenderHub is called by governance, it receives a list of multichain actions's. Each multichain action is a list of calls and a target chain Id. For each multichain action, the SenderHub dispatches the respective Encoder for that chain, then the Encoder returns to the SenderHub an address, call value, and encoded calldata such that the SenderHub can initiate the bridge call. This ensures the SenderHub is always the caller on L1.

Receiving Messages

The ReceiverHub assigns a Decoder module for a given calldata payload (by its selector). When the ReceiverHub is called, it dispatches the encoded data to the respective Decoder, then the Decoder validates the data, decodes it, and returns the originally sent list of calls for ReceiverHub to run. This ensures the ReceiverHub is always the caller on the remote chain.

---
config:
    theme: 'dark'
---
flowchart LR

    subgraph Ethereum
        S0[SenderHub]
        S1[SenderHub]

        E0[/Encoder/]
        E1[/Encoder/]
        E2[/Encoder/]
        E3[/Encoder/]

        S0 --> E0 --> S1
        S0 --> E1 --> S1
        S0 --> E2 --> S1
        S0 --> E3 --> S1
    end


    BM{Bridge\nMagic}
    S1 -.-> BM
    BM -.-> RA0
    BM -.-> RB0

    subgraph RCA[RemoteChain]
        RA0[ReceiverHub]
        RA1[ReceiverHub]
        DA0[/Decoder/]
        DA1[/Decoder/]
        PA((Protocol))

        RA0 --> DA0 --> RA1
        RA0 --> DA1 --> RA1
        RA1 --> PA
    end
    subgraph RCB[RemoteChain]
        RB0[ReceiverHub]
        RB1[ReceiverHub]
        DB0[/Decoder/]
        DB1[/Decoder/]
        PB((Protocol))

        RB0 --> DB0 --> RB1
        RB0 --> DB1 --> RB1
        RB1 --> PB
    end

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