diff --git a/contracts/reverseRegistrar/ReverseNamer.sol b/contracts/reverseRegistrar/ReverseNamer.sol
new file mode 100644
index 000000000..5798337f4
--- /dev/null
+++ b/contracts/reverseRegistrar/ReverseNamer.sol
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+interface IReverseRegistrarStub {
+    function setName(string memory name) external;
+}
+
+/// @notice https://docs.ens.domains/ensip/19/
+library ReverseNamer {
+    address constant MAINNET = address(0); // TODO: ENSv2 addr.reverse registrar
+    address constant MAINNET_ROLLUP =
+        0x0000000000D8e504002cC26E3Ec46D81971C1664;
+    address constant TESTNET_ROLLUP =
+        0x00000BeEF055f7934784D6d81b6BC86665630dbA;
+
+    function registrarFromChain(
+        uint256 chainId
+    ) internal pure returns (address) {
+        if (isMainnet(chainId)) {
+            return MAINNET;
+        } else if (isMainnetRollup(chainId)) {
+            return MAINNET_ROLLUP;
+        } else if (isTestnetRollup(chainId)) {
+            return TESTNET_ROLLUP;
+        } else {
+            return address(0);
+        }
+    }
+
+    function setName(string memory primary) internal {
+        address registrar = registrarFromChain(block.chainid);
+        if (registrar != address(0)) {
+            IReverseRegistrarStub(registrar).setName(primary);
+        }
+    }
+
+    function isMainnet(uint256 chainId) internal pure returns (bool) {
+        return
+            chainId == 1 || // mainnet
+            chainId == 17000 || // holesky
+            chainId == 560048 || // hoodi
+            chainId == 11155111; // sepolia
+    }
+
+    function isMainnetRollup(uint256 chainId) internal pure returns (bool) {
+        return
+            chainId == 10 || // optimism
+            chainId == 8453 || // base
+            chainId == 42161 || // arb1
+            chainId == 59144 || // linea
+            chainId == 534352; // scroll
+    }
+
+    function isTestnetRollup(uint256 chainId) internal pure returns (bool) {
+        return
+            chainId == 59141 || // linea-sepolia
+            chainId == 84532 || // base-sepolia
+            chainId == 421614 || // arb1-sepolia
+            chainId == 534351 || // scroll-sepolia
+            chainId == 11155420; // optimism-sepolia
+    }
+}
+
+/// @dev Compile-time guard to prevent being Ownable.
+contract NotOwnable {
+    function owner() internal pure {}
+}
+
+/// @notice Mixin for naming a contract once.
+contract NamedOnce is NotOwnable {
+    constructor(string memory primary) {
+        ReverseNamer.setName(primary);
+    }
+}
+
+/// @notice Mixin for delegated contract naming.
+contract NameableBy is NotOwnable {
+    address public nameOwner;
+
+    constructor(address owner, string memory primary) {
+        nameOwner = owner;
+        if (bytes(primary).length > 0) {
+            ReverseNamer.setName(primary);
+        }
+    }
+
+    /// @notice Set the name owner.
+    /// @dev Use `address(0)` to revoke ownership.
+    function setNameOwner(address owner) public {
+        require(msg.sender == nameOwner);
+        nameOwner = owner;
+    }
+
+    /// @notice Set contract primary name.
+    function setName(string memory primary) public {
+        require(msg.sender == nameOwner);
+        ReverseNamer.setName(primary);
+    }
+}
diff --git a/contracts/test/mocks/MockReverseNamer.sol b/contracts/test/mocks/MockReverseNamer.sol
new file mode 100644
index 000000000..b94ce965b
--- /dev/null
+++ b/contracts/test/mocks/MockReverseNamer.sol
@@ -0,0 +1,16 @@
+//SPDX-License-Identifier: MIT
+pragma solidity ^0.8.4;
+
+import {ReverseNamer} from "../../reverseRegistrar/ReverseNamer.sol";
+
+contract MockReverseNamer {
+    function registrarFromChain(
+        uint256 chainId
+    ) external pure returns (address) {
+        return ReverseNamer.registrarFromChain(chainId);
+    }
+}
+
+// import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
+// import {NamedOnce} from "../../reverseRegistrar/ReverseNamer.sol";
+// contract MockNamedOnce is Ownable, NamedOnce("") {} // compile-time error if Ownable
diff --git a/test/reverseRegistrar/TestReverseNamer.test.ts b/test/reverseRegistrar/TestReverseNamer.test.ts
new file mode 100644
index 000000000..21d98acb6
--- /dev/null
+++ b/test/reverseRegistrar/TestReverseNamer.test.ts
@@ -0,0 +1,141 @@
+import hre from 'hardhat'
+import { type Address, getAddress, zeroAddress } from 'viem'
+import { readdirSync, readFileSync } from 'node:fs'
+import { coinTypeFromChain } from '../fixtures/ensip19.js'
+
+const REVERSE_REGISTRAR_MAINNET_ROLLUP =
+  '0x0000000000D8e504002cC26E3Ec46D81971C1664'
+
+const connection = await hre.network.connect({
+  override: {
+    chainId: 8453, // appear like an L2
+  },
+})
+
+async function fixture() {
+  const [owner] = await connection.viem.getWalletClients()
+  const publicClient = await connection.viem.getPublicClient()
+  const reverseNamer = await connection.viem.deployContract('MockReverseNamer')
+  const l2ReverseRegistrar0 = await connection.viem.deployContract(
+    'L2ReverseRegistrar',
+    [coinTypeFromChain(connection.networkConfig.chainId!)],
+  )
+  await connection.networkHelpers.setCode(
+    REVERSE_REGISTRAR_MAINNET_ROLLUP,
+    (await publicClient.getCode(l2ReverseRegistrar0))!,
+  )
+  const l2ReverseRegistrar = await connection.viem.getContractAt(
+    'L2ReverseRegistrar',
+    REVERSE_REGISTRAR_MAINNET_ROLLUP,
+  )
+  return {
+    owner,
+    reverseNamer,
+    l2ReverseRegistrar,
+  }
+}
+
+const PRIMARY = 'mycontract.eth'
+
+describe('ReverseNamer', () => {
+  describe('registryFromChain', () => {
+    const dir = new URL('../../deployments/', import.meta.url)
+    for (const chainName of readdirSync(dir)) {
+      try {
+        const chainId = BigInt(
+          readFileSync(new URL(`./${chainName}/.chainId`, dir), {
+            encoding: 'utf8',
+          }),
+        )
+        const deploy = JSON.parse(
+          readFileSync(new URL(`./${chainName}/L2ReverseRegistrar.json`, dir), {
+            encoding: 'utf8',
+          }),
+        ) as { address: Address }
+        it(chainName, async () => {
+          const F = await connection.networkHelpers.loadFixture(fixture)
+          await expect(
+            F.reverseNamer.read.registrarFromChain([chainId]),
+          ).resolves.toStrictEqual(deploy.address)
+        })
+      } catch (err) {}
+    }
+  })
+
+  it('NamedOnce', async () => {
+    const F = await connection.networkHelpers.loadFixture(fixture)
+    const contract = await connection.viem.deployContract('NamedOnce', [
+      PRIMARY,
+    ])
+    await expect(
+      F.l2ReverseRegistrar.read.nameForAddr([contract.address]),
+    ).resolves.toStrictEqual(PRIMARY)
+  })
+
+  describe('NameableBy', () => {
+    it('w/o primary', async () => {
+      const F = await connection.networkHelpers.loadFixture(fixture)
+      const contract = await connection.viem.deployContract('NameableBy', [
+        F.owner.account.address,
+        '',
+      ])
+      await expect(
+        F.l2ReverseRegistrar.read.nameForAddr([contract.address]),
+        'primary',
+      ).resolves.toStrictEqual('')
+      await expect(contract.read.nameOwner()).resolves.toStrictEqual(
+        getAddress(F.owner.account.address),
+      )
+    })
+
+    it('w/primary', async () => {
+      const F = await connection.networkHelpers.loadFixture(fixture)
+      const contract = await connection.viem.deployContract('NameableBy', [
+        F.owner.account.address,
+        PRIMARY,
+      ])
+      await expect(
+        F.l2ReverseRegistrar.read.nameForAddr([contract.address]),
+        'primary',
+      ).resolves.toStrictEqual(PRIMARY)
+    })
+
+    it('setName', async () => {
+      const F = await connection.networkHelpers.loadFixture(fixture)
+      const contract = await connection.viem.deployContract('NameableBy', [
+        F.owner.account.address,
+        PRIMARY,
+      ])
+      const primary = 'new-name'
+      await contract.write.setName([primary])
+      await expect(
+        F.l2ReverseRegistrar.read.nameForAddr([contract.address]),
+      ).resolves.toStrictEqual(primary)
+    })
+
+    it('disown', async () => {
+      const F = await connection.networkHelpers.loadFixture(fixture)
+      const contract = await connection.viem.deployContract('NameableBy', [
+        F.owner.account.address,
+        PRIMARY,
+      ])
+      await contract.write.setNameOwner([zeroAddress])
+      await expect(contract.read.nameOwner()).resolves.toStrictEqual(
+        zeroAddress,
+      )
+    })
+
+    it('not owner', async () => {
+      const contract = await connection.viem.deployContract('NameableBy', [
+        zeroAddress,
+        PRIMARY,
+      ])
+      await expect(contract.write.setNameOwner([zeroAddress])).rejects.toThrow(
+        'reverted without a reason',
+      )
+      await expect(contract.write.setName([''])).rejects.toThrow(
+        'reverted without a reason',
+      )
+    })
+  })
+})