Compose Universal Bridge

function receiveTokens(
    MessageHeader msgHeader
) external returns (address token, uint256 amount) {
    /// Sanity checks
    require(msg.sender == msgHeader.receiver, "Only receiver can claim");
    require(msgHeader.chainDest == block.chainid, "Wrong destination chain");
    require(keccak256(bytes(msgHeader.label)) == keccak256("SEND_TOKENS"), "Wrong label");

    // 1) Read and consume SEND message
    bytes memory m = mailbox.read(msgHeader);
    if (m.length == 0) revert("No SEND_TOKENS message");

    uint256 remoteChainID;
    address remoteAsset;
    string memory name;
    string memory symbol;
    uint8 decimals;

    (remoteChainID, remoteAsset, amount, name, symbol, decimals) =
        abi.decode(m, (uint256, address, uint256, string, string, uint8));

    // 2) If this chain is the canonical chain for this asset and it holds native tokens,
    //    unlock the native asset. Otherwise, mint CET.
    if (remoteChainID == block.chainid && IERC20(remoteAsset).balanceOf(address(this)) >= amount) {
        IERC20(remoteAsset).transfer(msg.sender, amount);
        token = remoteAsset;  // native token on canonical chain
    } else {
        token = ensureCETAndMint(remoteAsset, remoteChainID, name, symbol, decimals, msg.sender, amount);
    }

    // 3) Write ACK to confirm to the source chain that this SEND has been processed
    mailbox.write(
        chainDest: msgHeader.chainSrc,
        receiver: msgHeader.sender,
        sessionId: msgHeader.sessionId,
        label: "ACK",
        payload: "",
    );
    emit TokensReceived(token, amount);

    return (token, amount);
}