diff --git a/.gitmodules b/.gitmodules
index 974254b..2386822 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,9 @@
 [submodule "evm/lib/forge-std"]
 	path = evm/lib/forge-std
 	url = https://github.com/foundry-rs/forge-std
+[submodule "evm/lib/openzeppelin-contracts"]
+	path = evm/lib/openzeppelin-contracts
+	url = https://github.com/Openzeppelin/openzeppelin-contracts
+[submodule "evm/lib/ERC721A"]
+	path = evm/lib/ERC721A
+	url = https://github.com/chiru-labs/ERC721A
diff --git a/evm/foundry.toml b/evm/foundry.toml
index 14a5117..cc90b82 100644
--- a/evm/foundry.toml
+++ b/evm/foundry.toml
@@ -3,6 +3,11 @@ solc_version = "0.8.23"
 optimizer = false
 via_ir = true
 
+remappings = [
+  "@escrin/=lib/escrin",
+  "erc721a/=lib/ERC721A",
+]
+
 [fmt]
 line_length = 100
 
diff --git a/evm/lib/ERC721A b/evm/lib/ERC721A
new file mode 160000
index 0000000..6f8a82a
--- /dev/null
+++ b/evm/lib/ERC721A
@@ -0,0 +1 @@
+Subproject commit 6f8a82a7b2833ad8b2fc7b54349281143a731fdd
diff --git a/evm/lib/escrin b/evm/lib/escrin
new file mode 160000
index 0000000..d7b551a
--- /dev/null
+++ b/evm/lib/escrin
@@ -0,0 +1 @@
+Subproject commit d7b551ad25a54a2bee01651c5f2c48e1ee30a5c7
diff --git a/evm/lib/openzeppelin-contracts b/evm/lib/openzeppelin-contracts
new file mode 160000
index 0000000..dbb6104
--- /dev/null
+++ b/evm/lib/openzeppelin-contracts
@@ -0,0 +1 @@
+Subproject commit dbb6104ce834628e473d2173bbc9d47f81a9eec3
diff --git a/evm/src/NFTrout.sol b/evm/src/NFTrout.sol
new file mode 100644
index 0000000..a15f370
--- /dev/null
+++ b/evm/src/NFTrout.sol
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.9;
+
+import {
+    ITaskAcceptor, TaskAcceptor
+} from "@escrin/evm/contracts/tasks/v1/acceptors/TaskAcceptor.sol";
+import {TimelockedDelegatedTaskAcceptor} from
+    "@escrin/evm/contracts/tasks/v1/acceptors/DelegatedTaskAcceptor.sol";
+import {TimelockedDelegatedTaskAcceptor} from
+    "@escrin/evm/contracts/tasks/v1/acceptors/DelegatedTaskAcceptor.sol";
+
+import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
+import {IERC20, SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import {Pausable} from "@openzeppelin/contracts/utils/Pausable.sol";
+import {Strings} from "@openzeppelin/contracts/utils/Strings.sol";
+import {MerkleProof} from "@openzeppelin/contracts/utils/cryptography/MerkleProof.sol";
+import {
+    IERC165, ERC165Checker
+} from "@openzeppelin/contracts/utils/introspection/ERC165Checker.sol";
+
+import {IERC721A, ERC721A} from "erc721a/contracts/ERC721A.sol";
+import {ERC721ABurnable} from "erc721a/contracts/extensions/ERC721ABurnable.sol";
+import {ERC721ABurnable} from "erc721a/contracts/extensions/ERC721ABurnable.sol";
+import {ERC721AQueryable} from "erc721a/contracts/extensions/ERC721AQueryable.sol";
+
+contract NFTrout is
+    ERC721A,
+    ERC721ABurnable,
+    ERC721AQueryable,
+    TimelockedDelegatedTaskAcceptor,
+    Ownable,
+    Pausable
+{
+    using SafeERC20 for IERC20;
+
+    type TokenId is uint256;
+
+    /// The token does not exist;
+    error NoSuchToken(TokenId id); // 08ff8e94 CP+OlA==
+
+    /// The trout is no longer breedable.
+    event Delisted();
+    event TasksAccepted();
+
+    struct ClaimRange {
+        uint256 startTokenId;
+        uint256 quantity;
+    }
+
+    bytes32 private immutable claimantsRoot;
+    string private urlPrefix;
+    string private urlSuffix;
+
+    IERC20 public immutable paymentToken;
+    uint256 public mintFee;
+    mapping(address => uint256) public earnings;
+    mapping(TokenId => uint256) public studFees;
+
+    constructor(
+        address upstreamAcceptor,
+        uint64 initialAcceptorTimelock,
+        address paymentTokenAddr,
+        uint256 numClaimants,
+        bytes32 claimantsMerkleRoot,
+        uint256 initialMintFee
+    )
+        ERC721A("NFTrout", "TROUT")
+        TimelockedDelegatedTaskAcceptor(upstreamAcceptor, initialAcceptorTimelock)
+        Ownable(msg.sender)
+    {
+        require(
+            ERC165Checker.supportsInterface(paymentTokenAddr, type(IERC20).interfaceId),
+            "bad payment token"
+        );
+
+        mintFee = initialMintFee;
+        claimantsRoot = claimantsMerkleRoot;
+
+        uint256 divisor = 9;
+        uint256 batches = numClaimants >> divisor;
+        uint256 remainder = numClaimants - (batches << divisor);
+        for (uint256 i; i < batches; i++) {
+            _mintERC2309(address(this), 1 << divisor);
+        }
+        if (remainder > 0) {
+            _mintERC2309(address(this), remainder);
+        }
+    }
+
+    function claim(address claimant, ClaimRange[] calldata ranges, bytes32[] calldata proof)
+        external
+    {
+        bytes32 leaf = keccak256(abi.encode(claimant, ranges));
+        if (!MerkleProof.verifyCalldata(proof, claimantsRoot, leaf)) revert Unauthorized();
+        for (uint256 i; i < ranges.length; i++) {
+            for (uint256 j; i < ranges[i].quantity; j++) {
+                safeTransferFrom(address(this), claimant, ranges[i].startTokenId + j);
+            }
+        }
+    }
+
+    function mint(uint256 quantity) external whenNotPaused {
+        uint256 fee = mintFee * quantity;
+        _earn(owner(), fee);
+        _safeMint(msg.sender, quantity);
+        paymentToken.safeTransferFrom(msg.sender, address(this), fee);
+    }
+
+    /// Breeds any two trout to produce a third trout that will be owned by the caller.
+    /// This method must be called with enough value to pay for the two trouts' fees and the minting fee.
+    function breed(TokenId[] calldata lefts, TokenId[] calldata rights) external whenNotPaused {
+        require(lefts.length == rights.length, "mismatched lengths");
+        uint256 quantity = lefts.length;
+
+        uint256 fee = _earn(owner(), quantity * mintFee);
+        for (uint256 i; i < quantity; i++) {
+            (TokenId left, TokenId right) = (lefts[i], rights[i]);
+            require(TokenId.unwrap(left) != TokenId.unwrap(right), "cannot self-breed");
+            if (!_exists(left)) revert NoSuchToken(left);
+            if (!_exists(right)) revert NoSuchToken(right);
+            fee += _earn(_ownerOf(left), getBreedingFee(msg.sender, left));
+            fee += _earn(_ownerOf(right), getBreedingFee(msg.sender, right));
+        }
+
+        _safeMint(msg.sender, quantity);
+
+        paymentToken.safeTransferFrom(msg.sender, address(this), fee);
+    }
+
+    /// Makes a trout not breedable.
+    function delist(TokenId tokenId) external {
+        if (msg.sender != _ownerOf(tokenId)) revert Unauthorized();
+        studFees[tokenId] = 0;
+        emit Delisted();
+    }
+
+    function withdraw() external {
+        uint256 stack = earnings[msg.sender];
+        earnings[msg.sender] = 0;
+        paymentToken.safeTransferFrom(address(this), msg.sender, stack);
+    }
+
+    function setUrlComponents(string calldata prefix, string calldata suffix) external onlyOwner {
+        (urlPrefix, urlSuffix) = (prefix, suffix);
+    }
+
+    function setMintFee(uint256 fee) external onlyOwner {
+        mintFee = fee;
+    }
+
+    function pause() external onlyOwner {
+        _pause();
+    }
+
+    function unpause() external onlyOwner {
+        _unpause();
+    }
+
+    /// Returns a cost for the payer to breed the trout that is no larger than the list price.
+    function getBreedingFee(address breeder, TokenId tokenId) public view returns (uint256) {
+        if (TokenId.unwrap(tokenId) == 0 || breeder == _ownerOf(tokenId)) return 0;
+        uint256 fee = studFees[tokenId];
+        if (fee == 0) revert Unauthorized();
+        return fee;
+    }
+
+    function tokenURI(uint256 tokenId)
+        public
+        view
+        override(IERC721A, ERC721A)
+        returns (string memory)
+    {
+        return string.concat(urlPrefix, Strings.toString(tokenId));
+    }
+
+    function supportsInterface(bytes4 interfaceId)
+        public
+        pure
+        override(IERC721A, ERC721A, TaskAcceptor)
+        returns (bool)
+    {
+        return interfaceId == type(IERC165).interfaceId
+            || interfaceId == type(ITaskAcceptor).interfaceId
+            || interfaceId == type(IERC721A).interfaceId;
+    }
+
+    struct Task {
+        TaskKind kind;
+        bytes payload;
+    }
+
+    enum TaskKind {
+        Unknown,
+        Mint,
+        Burn,
+        List
+    }
+
+    struct MintTask {
+        RecipentQuantity[] outputs;
+    }
+
+    struct RecipentQuantity {
+        address recipient;
+        uint256 quantity;
+    }
+
+    struct BurnTask {
+        TokenId[] tokens;
+    }
+
+    struct ListTask {
+        StudFee[] listings;
+    }
+
+    struct StudFee {
+        TokenId stud;
+        uint256 fee;
+    }
+
+    function _afterTaskResultsAccepted(
+        uint256[] calldata,
+        bytes calldata report,
+        TaskIdSelector memory
+    ) internal override {
+        Task[] memory tasks = abi.decode(report, (Task[]));
+        for (uint256 i; i < tasks.length; i++) {
+            Task memory task = tasks[i];
+
+            if (task.kind == TaskKind.Mint) {
+                MintTask memory mintTask = abi.decode(task.payload, (MintTask));
+                for (uint256 j; j < mintTask.outputs.length; j++) {
+                    _safeMint(mintTask.outputs[j].recipient, mintTask.outputs[j].quantity);
+                }
+                return;
+            }
+
+            if (task.kind == TaskKind.Burn) {
+                BurnTask memory burnTask = abi.decode(task.payload, (BurnTask));
+                for (uint256 j; j < burnTask.tokens.length; j++) {
+                    _burn(TokenId.unwrap(burnTask.tokens[j]));
+                }
+                return;
+            }
+
+            if (task.kind == TaskKind.List) {
+                ListTask memory listTask = abi.decode(task.payload, (ListTask));
+                for (uint256 j; j < listTask.listings.length; j++) {
+                    studFees[listTask.listings[j].stud] = listTask.listings[j].fee;
+                }
+                return;
+            }
+
+            revert("unknown task kind");
+        }
+        emit TasksAccepted();
+    }
+
+    function _afterTokenTransfers(address from, address, uint256 startTokenId, uint256 quantity)
+        internal
+        override
+    {
+        if (from == address(0)) return;
+        for (uint256 i = startTokenId; i < quantity; i++) {
+            studFees[TokenId.wrap(i)] = 0;
+        }
+    }
+
+    function _earn(address payee, uint256 amount) internal returns (uint256) {
+        earnings[payee] += amount;
+        return amount;
+    }
+
+    function _ownerOf(TokenId id) internal view returns (address) {
+        return ownerOf(TokenId.unwrap(id));
+    }
+
+    function _exists(TokenId id) internal view returns (bool) {
+        return _exists(TokenId.unwrap(id));
+    }
+
+    function _startTokenId() internal pure override returns (uint256) {
+        return 1;
+    }
+}