Add MultisigScriptDeposit extension for L1→L2 deposits

script/universal/MultisigScriptDeposit.sol

@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.15;
+
+import {CBMulticall} from "src/utils/CBMulticall.sol";
+
+import {MultisigScript} from "./MultisigScript.sol";
+import {Enum} from "./IGnosisSafe.sol";
+
+/// @notice Interface for OptimismPortal2's depositTransaction function
+interface IOptimismPortal2 {
+    /// @notice Creates a deposit transaction on L2
+    /// @param _to Target address on L2
+    /// @param _value ETH value to send with the transaction
+    /// @param _gasLimit Minimum gas limit for L2 execution
+    /// @param _isCreation Whether the transaction creates a contract
+    /// @param _data Calldata for the L2 transaction
+    function depositTransaction(address _to, uint256 _value, uint64 _gasLimit, bool _isCreation, bytes memory _data)
+        external
+        payable;
+}
+
+/// @title MultisigScriptDeposit
+/// @notice Extension of MultisigScript for L1 → L2 deposit transactions.
+///
+/// @dev This contract simplifies the creation of L1 multisig transactions that trigger actions on L2
+///      via the OptimismPortal's depositTransaction mechanism. Task writers only need to define the
+///      L2 calls they want to execute; this contract handles wrapping them in the appropriate
+///      depositTransaction call automatically.
+///
+///      Example usage:
+///      ```solidity
+///      contract MyL2Task is MultisigScriptDeposit {
+///          function _ownerSafe() internal view override returns (address) {
+///              return vm.envAddress("OWNER_SAFE");
+///          }
+///
+///          function _buildL2Calls() internal view override returns (CBMulticall.Call3Value[] memory) {
+///              CBMulticall.Call3Value[] memory calls = new CBMulticall.Call3Value[](1);
+///              calls[0] = CBMulticall.Call3Value({
+///                  target: L2_CONTRACT,
+///                  allowFailure: false,
+///                  callData: abi.encodeCall(IL2Contract.someFunction, (arg1, arg2)),
+///                  value: 0
+///              });
+///              return calls;
+///          }
+///      }
+///      ```
+///
+///      The example above uses the default implementation for `_optimismPortal()` (chain-based).
+///      Task writers must set the `L2_GAS_LIMIT` environment variable or override `_l2GasLimit()`.
+///
+/// @dev Future Enhancements:
+///      1. L2 Post-Check Hook: Currently, `_postCheck` runs on L1 and cannot verify L2 state changes.
+///         A future enhancement could add an `_postCheckL2` hook that forks L2 state and simulates
+///         the deposit transaction's effect. This is non-trivial because deposit transactions are
+///         not immediately reflected on L2.
+abstract contract MultisigScriptDeposit is MultisigScript {
+    //////////////////////////////////////////////////////////////////////////////////////
+    ///                                   Constants                                    ///
+    //////////////////////////////////////////////////////////////////////////////////////
+
+    /// @notice OptimismPortalProxy address on L1 Mainnet (for Base Mainnet)
+    address internal constant OPTIMISM_PORTAL_MAINNET = 0x49048044D57e1C92A77f79988d21Fa8fAF74E97e;
+
+    /// @notice OptimismPortalProxy address on L1 Sepolia (for Base Sepolia)
+    address internal constant OPTIMISM_PORTAL_SEPOLIA = 0x49f53e41452C74589E85cA1677426Ba426459e85;
+
+    //////////////////////////////////////////////////////////////////////////////////////
+    ///                               Virtual Functions                                ///
+    //////////////////////////////////////////////////////////////////////////////////////
+
+    /// @notice Returns the OptimismPortal address on L1
+    /// @dev Default implementation returns the correct address based on chain ID.
+    ///      Supports L1 Mainnet (chain 1) and L1 Sepolia (chain 11155111).
+    ///      Override this function for other chains or custom portal addresses.
+    function _optimismPortal() internal view virtual returns (address) {
+        if (block.chainid == 1) {
+            return OPTIMISM_PORTAL_MAINNET;
+        } else if (block.chainid == 11155111) {
+            return OPTIMISM_PORTAL_SEPOLIA;
+        }
+        revert("MultisigScriptDeposit: unsupported chain, override _optimismPortal()");
+    }
+
+    /// @notice Returns the minimum gas limit for L2 execution
+    /// @dev Default implementation reads from the `L2_GAS_LIMIT` environment variable.
+    ///      All signers must use the same gas limit to produce matching signatures.
+    ///
+    ///      To specify a fixed gas limit, override this function in your task contract:
+    ///      ```solidity
+    ///      function _l2GasLimit() internal pure override returns (uint64) {
+    ///          return 200_000; // Your estimated gas limit
+    ///      }
+    ///      ```
+    ///
+    ///      Common gas limit starting points:
+    ///      - Single simple call: 100,000 - 200,000
+    ///      - Multiple calls or complex operations: 500,000+
+    ///
+    ///      If the gas limit is too low, the L2 transaction will fail but the deposit
+    ///      will still be recorded (ETH may be stuck until manually recovered).
+    function _l2GasLimit() internal view virtual returns (uint64) {
+        return uint64(vm.envUint("L2_GAS_LIMIT"));
+    }
+
+    /// @notice Build the calls that will be executed on L2
+    /// @dev Task writers implement this to define what actions should occur on L2.
+    ///      These calls will be batched into a single CBMulticall.aggregate3Value call
+    ///      and wrapped in a depositTransaction to the OptimismPortal.
+    ///
+    ///      The `value` field in each Call3Value struct specifies ETH to send with that
+    ///      specific L2 call. The total ETH will be bridged via the deposit transaction.
+    /// @return calls Array of calls to execute on L2 via CBMulticall
+    function _buildL2Calls() internal view virtual returns (CBMulticall.Call3Value[] memory);
+
+    //////////////////////////////////////////////////////////////////////////////////////
+    ///                              Overridden Functions                              ///
+    //////////////////////////////////////////////////////////////////////////////////////
+
+    /// @notice Wraps L2 calls in a depositTransaction to the OptimismPortal
+    /// @dev Task writers should NOT override this function. Instead, implement `_buildL2Calls`
+    ///      to define the L2 operations. This function handles the L1 deposit wrapping automatically.
+    ///
+    ///      The L2 calls are encoded as a CBMulticall.aggregate3Value call, which is then
+    ///      passed as the data payload to OptimismPortal.depositTransaction. This allows
+    ///      multiple L2 operations to be batched into a single deposit transaction.
+    ///
+    ///      ETH bridging: If any L2 calls include a non-zero `value`, the total ETH is
+    ///      summed and sent with the deposit transaction. The CBMulticall.aggregate3Value
+    ///      function on L2 automatically distributes the ETH to each call according to its
+    ///      specified `value` field - no additional developer action is required.
+    function _buildCalls() internal view virtual override returns (Call[] memory) {
+        CBMulticall.Call3Value[] memory l2Calls = _buildL2Calls();
+        uint256 totalValue = _sumL2CallValues(l2Calls);
+
+        // Encode L2 calls as a multicall
+        // Note: We use aggregate3Value to support per-call ETH distribution on L2
+        bytes memory l2Data = abi.encodeCall(CBMulticall.aggregate3Value, (l2Calls));
+
+        // Wrap in depositTransaction call to OptimismPortal
+        Call[] memory l1Calls = new Call[](1);
+        l1Calls[0] = Call({
+            operation: Enum.Operation.Call,
+            target: _optimismPortal(),
+            data: abi.encodeCall(
+                IOptimismPortal2.depositTransaction,
+                (
+                    CB_MULTICALL, // L2 target: CBMulticall at same address on L2
+                    totalValue, // ETH to bridge
+                    _l2GasLimit(), // Gas limit for L2 execution
+                    false, // Not a contract creation
+                    l2Data // Encoded multicall
+                )
+            ),
+            value: totalValue
+        });
+
+        return l1Calls;
+    }
+
+    //////////////////////////////////////////////////////////////////////////////////////
+    ///                              Internal Functions                                ///
+    //////////////////////////////////////////////////////////////////////////////////////
+
+    /// @notice Sums the ETH values from an array of L2 calls
+    /// @param l2Calls The array of L2 calls to sum values from
+    /// @return total The total ETH value across all calls
+    function _sumL2CallValues(CBMulticall.Call3Value[] memory l2Calls) internal pure returns (uint256 total) {
+        for (uint256 i; i < l2Calls.length; i++) {
+            total += l2Calls[i].value;
+        }
+        return total;
+    }
+}

script/universal/README.md

@@ -14,6 +14,14 @@ This is the core script for building Forge scripts that interact with Gnosis Saf
 - **Workflows**: Provides standard functions for `sign` (generating signatures), `approve` (onchain approval for nested Safes), `simulate` (dry-run with state overrides), and `run` (execution).
 - **Simulation**: Integrates with `Simulation.sol` to provide detailed simulation links and state diffs.
 
+### `MultisigScriptDeposit.sol`
+
+An extension of `MultisigScript` for L1 → L2 deposit transactions. Task writers define L2 calls via `_buildL2Calls()`, and the framework automatically wraps them in an `OptimismPortal.depositTransaction` call. Features:
+
+- **ETH Bridging**: Supports bridging ETH along with the message.
+- **Chain-Aware Defaults**: Provides default `OptimismPortal` addresses for Mainnet and Sepolia.
+- **Gas Limit**: Set via `L2_GAS_LIMIT` env var (all signers must use the same value).
+
 ### `Simulation.sol`
 
 A library for simulating multisig transactions with state overrides. It is particularly useful for: