Provide detailed PR description for HopV2 implementation

[Copilot]

Responded to request for comprehensive PR documentation explaining the HopV2 protocol upgrade and architectural changes.

Response Content

Provided detailed technical overview covering:

• Core architecture: Unified HopV2 base contract with namespaced storage (ERC-7201), inherited by both FraxtalHopV2 and RemoteHopV2
• New interface: Extended sendOFT() to accept _dstGas and _data parameters for arbitrary cross-chain execution
• Compose pattern: Recipients implement IHopComposer.hopCompose() to receive tokens + data and execute custom logic
• Remote admin system: RemoteAdmin contracts enable Fraxtal multisig to configure destination chains via hop messages
• Security enhancements: Message replay protection, trusted hop validation, pause controls
• Dependency upgrade: OpenZeppelin 5.x for storage namespacing (prevents storage collisions during upgrades)

Interface Comparison

Old:

function sendOFT(address _oft, uint32 _dstEid, bytes32 _to, uint256 _amountLD)

New:

function sendOFT(
    address _oft,
    uint32 _dstEid,
    bytes32 _recipient,
    uint256 _amountLD,
    uint128 _dstGas,      // Gas for destination execution
    bytes memory _data    // Arbitrary payload
)

Recipients implementing IHopComposer receive callback:

function hopCompose(
    uint32 _srcEid,
    bytes32 _sender,
    address _oft,
    uint256 _amount,
    bytes memory _data
) external

No code changes were made - this was a documentation request addressed via PR comment response.

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[pegahcarter]

@copilot also describe RemoteVault and it's functionality.

[Copilot]

@copilot also describe RemoteVault and it's functionality.

RemoteVaultHop System

The RemoteVaultHop system enables users to deposit into and redeem from ERC-4626 vaults on remote chains using cross-chain token hops.

Architecture

1. RemoteVaultHop Contract

• Core orchestrator implementing IHopComposer to handle vault operations across chains
• Manages both local vaults (on the same chain) and remote vaults (on other chains)
• Tracks user deposits via synthetic RemoteVaultDeposit ERC20 tokens

2. RemoteVaultDeposit Contract

• ERC20 receipt token representing user deposits in remote vaults
• Tracks price-per-share with linear interpolation over 100 blocks for smooth price updates
• Provides convenience methods: deposit() and redeem() forward calls to RemoteVaultHop
• Users interact with this token to manage their remote vault positions

Cross-Chain Vault Operations

Deposit Flow (Chain A → Vault on Chain B):

1. User calls RemoteVaultDeposit.deposit(_amount) on Chain A
2. Transfers tokens to RemoteVaultHop and calls HOP.sendOFT() with Action.Deposit message
3. RemoteVaultHop on Chain B receives via hopCompose(), calls vault.deposit()
4. Chain B sends Action.DepositReturn message back with shares received + vault price-per-share
5. Chain A receives return message, mints RemoteVaultDeposit tokens to user, updates price

Redeem Flow (Chain A ← Vault on Chain B):

1. User calls RemoteVaultDeposit.redeem(_amount) on Chain A (burns deposit tokens)
2. Sends Action.Redeem message to Chain B
3. Chain B calls vault.redeem(), sends tokens back with Action.RedeemReturn message
4. Chain A receives underlying tokens, transfers to user

Key Features

Storage Mappings:

• vaultShares: Maps local vault addresses to their share tokens (ERC-4626)
• balance[vault][srcEid][srcAddress]: Tracks shares owned per vault per remote user
• depositToken[eid][vault]: Maps remote vaults to their synthetic RemoteVaultDeposit tokens
• remoteVaultHops[eid]: Registry of RemoteVaultHop addresses on other chains

Message Types (Actions enum):

• Deposit: Initial deposit request to remote vault
• DepositReturn: Confirmation with shares minted + price update
• Redeem: Redemption request from remote vault
• RedeemReturn: Underlying tokens returned + price update

Fee Calculation:
The quote() function calculates round-trip fees including:

• A → Fraxtal (or A → Fraxtal → B for cross-remote deposits)
• Return journey fees (Fraxtal → A or B → Fraxtal → A)
• Accounts for 3-hop scenarios when neither chain is Fraxtal

Security:

• Only RemoteVaultHop can mint/burn RemoteVaultDeposit tokens
• Validates incoming messages are from registered RemoteVaultHops
• recover() function for emergency fund rescue (added in commit a529d88)