feat: add fee distributor

src/Constants.sol

@@ -15,3 +15,6 @@ address constant VALIDATOR_MANAGER_ADDRESS = 0x662530000000000000000000000000000
 
 /// @dev The address of the Registrar predeployed contract on Noble.
 address constant REGISTRAR_ADDRESS = 0x6625300000000000000000000000000000000003;
+
+/// @dev The address of the FeeDistributor predeployed contract on Noble.
+address constant FEE_DISTRIBUTOR_ADDRESS = 0x6625300000000000000000000000000000000004;

src/interfaces/IFeeDistributor.sol

@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+pragma solidity >=0.8.13 <0.9.0;
+
+/// @title IFeeDistributor
+/// @notice Interface for the Fee Distributor contract.
+interface IFeeDistributor {
+    // =========================================================================
+    // Types
+    // =========================================================================
+
+    /// @notice Return struct for recipient information.
+    struct RecipientInfo {
+        address recipient;
+        uint16 bps;
+    }
+
+    // =========================================================================
+    // Events
+    // =========================================================================
+
+    /// @notice Emitted when a recipient is added or updated.
+    /// @param recipient The recipient address.
+    /// @param bps The new share of fees in basis points.
+    event RecipientSet(address indexed recipient, uint16 bps);
+
+    /// @notice Emitted when a recipient is removed.
+    /// @param recipient The recipient address.
+    event RecipientRemoved(address indexed recipient);
+
+    // =========================================================================
+    // Errors
+    // =========================================================================
+
+    /// @notice Error when the caller is not authorized.
+    error Unauthorized();
+
+    /// @notice Error when zero basis points is provided.
+    error ZeroBps();
+
+    /// @notice Error when total basis points exceeds 10,000.
+    error TotalBpsExceeded(uint16 totalBps);
+
+    /// @notice Error when the recipient does not exist.
+    error RecipientNotFound(address recipient);
+
+    // =========================================================================
+    // Functions
+    // =========================================================================
+
+    /// @notice Sets or updates a recipient's share in basis points.
+    /// @param recipient The address to receive fees.
+    /// @param bps The share of fees in basis points.
+    function setRecipient(address recipient, uint16 bps) external;
+
+    /// @notice Removes a recipient from fee distribution.
+    /// @param recipient The address to remove.
+    function removeRecipient(address recipient) external;
+
+    /// @notice Distributes the contract's native balance to recipients.
+    /// @dev Called during block finalization outside of the normal transaction
+    /// lifecycle. Implementations must not revert. Each recipient receives a
+    /// portion of the balance according to their configured basis points. Any
+    /// remainder is sent to the current block proposer's fee recipient address.
+    function distribute() external;
+
+    /// @notice Returns all current recipients and their basis points.
+    /// @return recipients The array of recipient addresses and their shares.
+    function getRecipients() external view returns (RecipientInfo[] memory recipients);
+}

src/interfaces/IValidatorManager.sol

@@ -16,20 +16,23 @@ interface IValidatorManager {
         uint32 ip;
         uint16 port;
         bytes32 publicKey;
+        address feeRecipient;
         bytes32 name;
     }
 
     /// @notice Return struct for view functions.
     struct ValidatorInfo {
         uint64 index;
         bytes32 publicKey;
+        address feeRecipient;
         string name;
         string socketAddress;
     }
 
     /// @notice Input struct for genesis validators.
     struct GenesisValidator {
         bytes32 publicKey;
+        address feeRecipient;
         bytes32 name;
         uint32 ip;
         uint16 port;
@@ -45,10 +48,16 @@ interface IValidatorManager {
     /// @notice Emitted when a validator is removed.
     event ValidatorRemoved(uint64 indexed index, bytes32 indexed publicKey, string name, uint64 epochRemoved);
 
+    /// @notice Emitted when a validator's fee recipient is updated.
+    event FeeRecipientUpdated(bytes32 indexed publicKey, address oldFeeRecipient, address newFeeRecipient);
+
     // =========================================================================
     // Errors
     // =========================================================================
 
+    /// @notice Error when the caller is not authorized.
+    error Unauthorized();
+
     /// @notice Error when a validator is already added.
     error ValidatorAlreadyAdded(bytes32 publicKey);
 
@@ -64,15 +73,25 @@ interface IValidatorManager {
 
     /// @notice Adds a new validator to the set, applied from the next epoch.
     /// @param publicKey The validator's public key.
+    /// @param feeRecipient The address that receives fees on behalf of the validator.
     /// @param name The validator's name.
     /// @param ip The validator's IPv4 address.
     /// @param port The validator's port.
-    function addValidator(bytes32 publicKey, bytes32 name, uint32 ip, uint16 port) external;
+    function addValidator(bytes32 publicKey, address feeRecipient, bytes32 name, uint32 ip, uint16 port) external;
 
     /// @notice Removes a validator from the set, applied from the next epoch.
     /// @param publicKey The validator's public key.
     function removeValidator(bytes32 publicKey) external;
 
+    /// @notice Updates the fee recipient address for a validator.
+    /// @param publicKey The validator's public key.
+    /// @param feeRecipient The new address that receives fees on behalf of the validator.
+    function setFeeRecipient(bytes32 publicKey, address feeRecipient) external;
+
+    /// @notice Returns the fee recipient address for a validator.
+    /// @param publicKey The validator's public key.
+    function getFeeRecipient(bytes32 publicKey) external view returns (address);
+
     /// @notice Returns validators active in the current epoch.
     function getCurrentValidators() external view returns (ValidatorInfo[] memory);