feat: non fungible

solidity/contracts/GovernanceUtils.sol

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-3.0-only
 
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 library GovernanceUtils {
     /// @notice Reverts if the governance delay has not passed since

solidity/contracts/Timelock.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-3.0-only
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 import "@openzeppelin/contracts/governance/TimelockController.sol";
 

solidity/contracts/bank/Bank.sol

@@ -13,7 +13,7 @@
 //               ▐████▌    ▐████▌
 //               ▐████▌    ▐████▌
 
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 import "@openzeppelin/contracts/access/Ownable.sol";
 

solidity/contracts/bank/IReceiveBalanceApproval.sol

@@ -13,7 +13,7 @@
 //               ▐████▌    ▐████▌
 //               ▐████▌    ▐████▌
 
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 /// @title IReceiveBalanceApproval
 /// @notice `IReceiveBalanceApproval` is an interface for a smart contract

solidity/contracts/bridge/BitcoinTx.sol

@@ -13,7 +13,7 @@
 //               ▐████▌    ▐████▌
 //               ▐████▌    ▐████▌
 
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 import {BTCUtils} from "@keep-network/bitcoin-spv-sol/contracts/BTCUtils.sol";
 import {BytesLib} from "@keep-network/bitcoin-spv-sol/contracts/BytesLib.sol";

solidity/contracts/bridge/Bridge.sol

@@ -13,7 +13,7 @@
 //               ▐████▌    ▐████▌
 //               ▐████▌    ▐████▌
 
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 import "@keep-network/random-beacon/contracts/Governable.sol";
 import "@keep-network/random-beacon/contracts/ReimbursementPool.sol";
@@ -32,6 +32,7 @@ import "./EcdsaLib.sol";
 import "./Wallets.sol";
 import "./Fraud.sol";
 import "./MovingFunds.sol";
+import "./ReservedDeposit.sol";
 
 import "../bank/IReceiveBalanceApproval.sol";
 import "../bank/Bank.sol";
@@ -70,6 +71,7 @@ contract Bridge is
     using MovingFunds for BridgeState.Storage;
     using Wallets for BridgeState.Storage;
     using Fraud for BridgeState.Storage;
+    using ReservedDeposit for BridgeState.Storage;
 
     BridgeState.Storage internal self;
 
@@ -464,6 +466,52 @@ contract Bridge is
         self.submitDepositSweepProof(sweepTx, sweepProof, mainUtxo, vault);
     }
 
+    /// @notice Reveals a deposit with UTXO reservation for tax-efficient custody.
+    ///         Allows depositors to reserve a specific Bitcoin UTXO and later redeem
+    ///         the exact same BTC, maintaining custody continuity for tax purposes.
+    ///         The depositor receives tBTC minus a storage fee (0.1% annually,
+    ///         minimum 0.01 BTC per year).
+    /// @param fundingTx Bitcoin funding transaction data.
+    /// @param reveal Deposit reveal data including wallet and refund information.
+    /// @param reservationDays Number of days to reserve the UTXO (1-1460 days).
+    /// @param btcRedemptionAddress Pre-committed Bitcoin address (20 or 32 bytes)
+    ///        where the BTC will be sent upon redemption.
+    /// @dev Storage fee is split: 90% to treasury immediately, 10% reserved for
+    ///      liquidation incentive. Maintains perfect 1:1 BTC:tBTC backing.
+    function revealReservedDeposit(
+        BitcoinTx.Info calldata fundingTx,
+        Deposit.DepositRevealInfo calldata reveal,
+        uint32 reservationDays,
+        bytes calldata btcRedemptionAddress
+    ) external {
+        self.revealReservedDeposit(
+            fundingTx,
+            reveal,
+            msg.sender,
+            reservationDays,
+            btcRedemptionAddress
+        );
+    }
+
+    /// @notice Redeems a reserved deposit, returning the depositor's tBTC to the
+    ///         Bridge and queuing a Bitcoin transaction to send the exact same
+    ///         UTXO back to the pre-committed redemption address.
+    /// @param utxoHash Hash of the reserved UTXO to redeem.
+    /// @dev Can only be called by the original depositor before reservation expiry.
+    ///      Burns the depositor's tBTC and sends liquidation bonus to treasury.
+    function redeemReservedDeposit(bytes32 utxoHash) external {
+        self.redeemReservedDeposit(utxoHash, msg.sender);
+    }
+
+    /// @notice Liquidates an expired reservation, releasing the UTXO back to the
+    ///         general pool and rewarding the liquidator with a bonus.
+    /// @param utxoHash Hash of the expired reservation to liquidate.
+    /// @dev Liquidator receives 10% of the original storage fee as incentive.
+    ///      Can be called by anyone after reservation expiry.
+    function liquidateExpiredReservation(bytes32 utxoHash) external {
+        self.liquidateExpiredReservation(utxoHash, msg.sender);
+    }
+
     /// @notice Requests redemption of the given amount from the specified
     ///         wallet to the redeemer Bitcoin output script. Handles the
     ///         simplest case in which the redeemer's balance is decreased in
@@ -1636,6 +1684,39 @@ contract Bridge is
         return self.liveWalletsCount;
     }
 
+    /// @notice Gets details about a reserved deposit.
+    /// @param utxoHash The hash of the reserved UTXO.
+    /// @return Reserved deposit details.
+    function reservedDeposits(bytes32 utxoHash)
+        external
+        view
+        returns (BridgeState.ReservedDeposit memory)
+    {
+        return self.reservedDeposits[utxoHash];
+    }
+
+    /// @notice Gets details about a priority redemption request.
+    /// @param redemptionKey The key identifying the redemption request.
+    /// @return Priority redemption details.
+    function priorityRedemptions(bytes32 redemptionKey)
+        external
+        view
+        returns (BridgeState.PriorityRedemption memory)
+    {
+        return self.priorityRedemptions[redemptionKey];
+    }
+
+    /// @notice Gets all reservation UTXOs for a depositor.
+    /// @param depositor The address of the depositor.
+    /// @return Array of UTXO hashes for the depositor's reservations.
+    function getDepositorReservations(address depositor)
+        external
+        view
+        returns (bytes32[] memory)
+    {
+        return self.depositorReservations[depositor];
+    }
+
     /// @notice Returns the fraud challenge identified by the given key built
     ///         as keccak256(walletPublicKey|sighash).
     function fraudChallenges(uint256 challengeKey)

solidity/contracts/bridge/BridgeGovernance.sol

@@ -13,7 +13,7 @@
 //               ▐████▌    ▐████▌
 //               ▐████▌    ▐████▌
 
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 import "@openzeppelin/contracts/access/Ownable.sol";
 import "./BridgeGovernanceParameters.sol";

solidity/contracts/bridge/BridgeGovernanceParameters.sol

@@ -13,7 +13,7 @@
 //               ▐████▌    ▐████▌
 //               ▐████▌    ▐████▌
 
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 /// @title Bridge Governance library for storing updatable parameters.
 library BridgeGovernanceParameters {

solidity/contracts/bridge/BridgeState.sol

@@ -13,7 +13,7 @@
 //               ▐████▌    ▐████▌
 //               ▐████▌    ▐████▌
 
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 import {IWalletRegistry as EcdsaWalletRegistry} from "@keep-network/ecdsa/contracts/api/IWalletRegistry.sol";
 import "@keep-network/random-beacon/contracts/ReimbursementPool.sol";
@@ -28,6 +28,9 @@ import "./MovingFunds.sol";
 import "../bank/Bank.sol";
 
 library BridgeState {
+    bytes32 internal constant RESERVED_DEPOSIT_EXTRA_DATA =
+        keccak256("tbtc-reserved-deposit");
+
     struct Storage {
         // Address of the Bank the Bridge belongs to.
         Bank bank;
@@ -320,14 +323,64 @@ library BridgeState {
         // Address of the redemption watchtower. The redemption watchtower
         // is responsible for vetoing redemption requests.
         address redemptionWatchtower;
+
+        // Reserved Deposit Storage
+        mapping(bytes32 => ReservedDeposit) reservedDeposits;
+        mapping(address => bytes32[]) depositorReservations;
+        mapping(bytes32 => PriorityRedemption) priorityRedemptions;
+
         // Reserved storage space in case we need to add more variables.
         // The convention from OpenZeppelin suggests the storage space should
         // add up to 50 slots. Here we want to have more slots as there are
         // planned upgrades of the Bridge contract. If more entires are added to
         // the struct in the upcoming versions we need to reduce the array size.
         // See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
         // slither-disable-next-line unused-state
-        uint256[49] __gap;
+        // Reduced from 49 to 46 to account for 3 new storage slots used above
+        uint256[46] __gap;
+    }
+
+    /// @notice Represents a BTC UTXO reservation for tax-efficient custody
+    struct ReservedDeposit {
+        bytes32 utxoHash;           // Hash of the UTXO
+        address depositor;          // Original depositor address
+        uint64 btcAmount;           // Amount of BTC deposited (satoshis)
+        uint64 tbtcMinted;          // Amount of tBTC minted to user
+        uint64 treasuryFee;         // Fee that went to treasury (90% of storage fee)
+        uint64 liquidationBonus;     // Reserved for liquidator/treasury (10% of storage fee)
+        uint256 depositTimestamp;   // When the deposit was made
+        uint256 expiryTimestamp;    // When the reservation expires
+        bytes btcRedemptionAddress; // Pre-committed BTC redemption address
+        bytes20 walletPubKeyHash;   // Wallet that holds this UTXO
+        uint32 fundingOutputIndex;  // Output index in the funding transaction
+        bool isActive;              // Whether reservation is still active
+    }
+
+    /// @notice Represents a priority redemption for reserved UTXOs
+    struct PriorityRedemption {
+        bytes32 utxoHash;                // Hash of the UTXO to redeem
+        bytes20 walletPubKeyHash;        // Wallet handling the redemption
+        address redeemer;                // Address requesting redemption
+        bytes redeemerOutputScript;      // Bitcoin script for redemption
+        uint64 requestedAmount;          // Amount to redeem (satoshis)
+        uint64 treasuryFee;              // Treasury fee (0 for reserved)
+        uint64 txMaxFee;                 // Max transaction fee
+        uint256 requestedAt;             // When redemption was requested
+        bool isPriority;                 // Flag for priority processing
+    }
+
+    struct ReservationProcessingContext {
+        uint64 btcAmount;
+        uint64 totalFee;
+        uint64 liquidationBonus;
+        uint256 expiryTimestamp;
+    }
+
+    struct ReservedSweepResult {
+        address depositor;
+        uint256 mintAmount;
+        uint256 treasuryFee;
+        uint256 liquidationBonus;
     }
 
     event DepositParametersUpdated(

solidity/contracts/bridge/Deposit.sol

@@ -13,7 +13,7 @@
 //               ▐████▌    ▐████▌
 //               ▐████▌    ▐████▌
 
-pragma solidity 0.8.17;
+pragma solidity ^0.8.17;
 
 import {BTCUtils} from "@keep-network/bitcoin-spv-sol/contracts/BTCUtils.sol";
 import {BytesLib} from "@keep-network/bitcoin-spv-sol/contracts/BytesLib.sol";