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Overview

MeltBridge is deployed on each source chain (Ethereum, Arbitrum, etc.). It implements the “Lock” side of the Lock & Mint pattern — locking user tokens and sending LayerZero messages to MeltHub on HyperEVM. Inherits: OApp (LayerZero), Pausable, ReentrancyGuard

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Constructor

constructor(address _lzEndpoint, address _owner, uint32 _hyperEvmEid)
ParameterDescription
_lzEndpointLayerZero endpoint on this source chain
_ownerContract owner
_hyperEvmEidLayerZero endpoint ID of HyperEVM (destination)

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Bridge In

function bridge(
    address token,
    uint256 amount,
    bytes32 recipient,
    bool toCore
) external payable returns (MessagingReceipt memory)
Bridges tokens from source chain to HyperEVM.
ParameterDescription
tokenERC20 token address to bridge
amountAmount to bridge
recipientRecipient address on HyperEVM (as bytes32)
toCoreIf true, auto-routes to HyperCore after minting
Flow:
  1. Validates token is supported and amount > 0
  2. Transfers tokens from user → locks in contract
  3. Encodes payload and sends via LayerZero
  4. Gas limit: 200k base, 400k if toCore (needs extra gas for HyperCore precompile calls)
Requires msg.value for LayerZero fees. Use quoteBridge first.

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quoteBridge

function quoteBridge(
    address token,
    uint256 amount,
    bytes32 recipient,
    bool toCore
) external view returns (MessagingFee memory)
Returns estimated LayerZero fee.

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Bridge Back (Receive)

When MeltHub sends a bridge-back message, _lzReceive handles it:
  1. Validates message is from HyperEVM
  2. Decodes: (token, recipient, amount)
  3. Checks token is supported and sufficient locked balance exists
  4. Releases locked tokens to recipient
  5. Emits BridgeCompleted

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Admin Functions

FunctionDescription
addToken(address)Add token to supported list
removeToken(address)Remove token from supported list
pause() / unpause()Pause/unpause bridge operations

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View Functions

FunctionReturns
isTokenSupported(token)Whether token can be bridged
getLockedBalance(token)Amount of token locked in contract

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Events

EventEmitted When
TokenAddedNew token added to supported list
TokenRemovedToken removed from supported list
BridgeInitiatedBridge-in transaction sent
BridgeCompletedBridge-back tokens released