Adding doc comments to the chain contracts (#530)

Signed-off-by: Danil <deniallugo@gmail.com>
Co-authored-by: Lyova Potyomkin <lyova.potyomkin@gmail.com>
Co-authored-by: kelemeno <kl@matterlabs.dev>
Co-authored-by: Stanislav Bezkorovainyi <stanislavbezkor@gmail.com>
Co-authored-by: Raid Ateir <ra@matterlabs.dev>
Co-authored-by: kelemeno <34402761+kelemeno@users.noreply.github.com>
Co-authored-by: Jmunoz <juanmunoz890@gmail.com>
Co-authored-by: Bence Haromi <bence.haromi@gmail.com>
Co-authored-by: Danil <deniallugo@gmail.com>

l1-contracts/contracts/bridge/L1SharedBridge.sol

@@ -156,7 +156,7 @@ contract L1SharedBridge is IL1SharedBridge, ReentrancyGuard, Ownable2StepUpgrade
     }
 
     /// @dev This sets the first post upgrade batch for era, used to check old withdrawals
-    /// @param  _eraLegacyBridgeLastDepositBatch The the zkSync Era batch number that processes the last deposit tx initiated by the legacy bridge
+    /// @param _eraLegacyBridgeLastDepositBatch The the zkSync Era batch number that processes the last deposit tx initiated by the legacy bridge
     /// @param _eraLegacyBridgeLastDepositTxNumber The tx number in the _eraLegacyBridgeLastDepositBatch of the last deposit tx initiated by the legacy bridge
     function setEraLegacyBridgeLastDepositTime(
         uint256 _eraLegacyBridgeLastDepositBatch,
@@ -168,7 +168,10 @@ contract L1SharedBridge is IL1SharedBridge, ReentrancyGuard, Ownable2StepUpgrade
         eraLegacyBridgeLastDepositTxNumber = _eraLegacyBridgeLastDepositTxNumber;
     }
 
-    /// @dev transfer tokens from legacy erc20 bridge or mailbox and set chainBalance as part of migration process
+    /// @dev Transfer tokens from legacy erc20 bridge or mailbox and set chainBalance as part of migration process.
+    /// @param _token The address of token to be transferred (address(1) for ether and contract address for ERC20).
+    /// @param _target The hyperchain or bridge contract address from where to transfer funds.
+    /// @param _targetChainId The chain ID of the corresponding hyperchain.
     function transferFundsFromLegacy(address _token, address _target, uint256 _targetChainId) external onlySelf {
         if (_token == ETH_TOKEN_ADDRESS) {
             uint256 balanceBefore = address(this).balance;
@@ -204,6 +207,8 @@ contract L1SharedBridge is IL1SharedBridge, ReentrancyGuard, Ownable2StepUpgrade
         }
     }
 
+    /// @dev Accepts ether only from the hyperchain associated with the specified chain ID.
+    /// @param _chainId The chain ID corresponding to the hyperchain allowed to send ether.
     function receiveEth(uint256 _chainId) external payable {
         require(BRIDGE_HUB.getHyperchain(_chainId) == msg.sender, "receiveEth not state transition");
     }
@@ -215,6 +220,10 @@ contract L1SharedBridge is IL1SharedBridge, ReentrancyGuard, Ownable2StepUpgrade
 
     /// @notice Allows bridgehub to acquire mintValue for L1->L2 transactions.
     /// @dev If the corresponding L2 transaction fails, refunds are issued to a refund recipient on L2.
+    /// @param _chainId The chain ID of the hyperchain to which deposit.
+    /// @param _prevMsgSender The `msg.sender` address from the external call that initiated current one.
+    /// @param _l1Token The L1 token address which is deposited.
+    /// @param _amount The total amount of tokens to be bridged.
     function bridgehubDepositBaseToken(
         uint256 _chainId,
         address _prevMsgSender,
@@ -250,6 +259,10 @@ contract L1SharedBridge is IL1SharedBridge, ReentrancyGuard, Ownable2StepUpgrade
     }
 
     /// @notice Initiates a deposit transaction within Bridgehub, used by `requestL2TransactionTwoBridges`.
+    /// @param _chainId The chain ID of the hyperchain to which deposit.
+    /// @param _prevMsgSender The `msg.sender` address from the external call that initiated current one.
+    /// @param _l2Value The L2 `msg.value` from the L1 -> L2 deposit transaction.
+    /// @param _data The calldata for the second bridge deposit.
     function bridgehubDeposit(
         uint256 _chainId,
         address _prevMsgSender,
@@ -315,6 +328,9 @@ contract L1SharedBridge is IL1SharedBridge, ReentrancyGuard, Ownable2StepUpgrade
 
     /// @notice Confirms the acceptance of a transaction by the Mailbox, as part of the L2 transaction process within Bridgehub.
     /// This function is utilized by `requestL2TransactionTwoBridges` to validate the execution of a transaction.
+    /// @param _chainId The chain ID of the hyperchain to which confirm the deposit.
+    /// @param _txDataHash The keccak256 hash of abi.encode(msgSender, l1Token, amount)
+    /// @param _txHash The hash of the L1->L2 transaction to confirm the deposit.
     function bridgehubConfirmL2Transaction(
         uint256 _chainId,
         bytes32 _txDataHash,
@@ -665,6 +681,7 @@ contract L1SharedBridge is IL1SharedBridge, ReentrancyGuard, Ownable2StepUpgrade
     /// of processing an L2 transaction where tokens would be minted.
     /// @dev If the token is bridged for the first time, the L2 token contract will be deployed. Note however, that the
     /// newly-deployed token does not support any custom logic, i.e. rebase tokens' functionality is not supported.
+    /// @param _prevMsgSender The `msg.sender` address from the external call that initiated current one.
     /// @param _l2Receiver The account address that should receive funds on L2
     /// @param _l1Token The L1 token address which is deposited
     /// @param _amount The total amount of tokens to be bridged

l1-contracts/contracts/bridgehub/Bridgehub.sol

@@ -16,6 +16,11 @@ import {ETH_TOKEN_ADDRESS, TWO_BRIDGES_MAGIC_VALUE, BRIDGEHUB_MIN_SECOND_BRIDGE_
 import {BridgehubL2TransactionRequest, L2Message, L2Log, TxStatus} from "../common/Messaging.sol";
 import {AddressAliasHelper} from "../vendor/AddressAliasHelper.sol";
 
+/// @author Matter Labs
+/// @custom:security-contact security@matterlabs.dev
+/// @dev The Bridgehub contract serves as the primary entry point for L1<->L2 communication,
+/// facilitating interactions between end user and bridges.
+/// It also manages state transition managers, base tokens, and chain registrations.
 contract Bridgehub is IBridgehub, ReentrancyGuard, Ownable2StepUpgradeable, PausableUpgradeable {
     /// @notice all the ether is held by the weth bridge
     IL1SharedBridge public sharedBridge;
@@ -155,6 +160,12 @@ contract Bridgehub is IBridgehub, ReentrancyGuard, Ownable2StepUpgradeable, Paus
     //// Mailbox forwarder
 
     /// @notice forwards function call to Mailbox based on ChainId
+    /// @param _chainId The chain ID of the hyperchain where to prove L2 message inclusion.
+    /// @param _batchNumber The executed L2 batch number in which the message appeared
+    /// @param _index The position in the L2 logs Merkle tree of the l2Log that was sent with the message
+    /// @param _message Information about the sent message: sender address, the message itself, tx index in the L2 batch where the message was sent
+    /// @param _proof Merkle proof for inclusion of L2 log that was sent with the message
+    /// @return Whether the proof is valid
     function proveL2MessageInclusion(
         uint256 _chainId,
         uint256 _batchNumber,
@@ -167,6 +178,12 @@ contract Bridgehub is IBridgehub, ReentrancyGuard, Ownable2StepUpgradeable, Paus
     }
 
     /// @notice forwards function call to Mailbox based on ChainId
+    /// @param _chainId The chain ID of the hyperchain where to prove L2 log inclusion.
+    /// @param _batchNumber The executed L2 batch number in which the log appeared
+    /// @param _index The position of the l2log in the L2 logs Merkle tree
+    /// @param _log Information about the sent log
+    /// @param _proof Merkle proof for inclusion of the L2 log
+    /// @return Whether the proof is correct and L2 log is included in batch
     function proveL2LogInclusion(
         uint256 _chainId,
         uint256 _batchNumber,
@@ -179,6 +196,15 @@ contract Bridgehub is IBridgehub, ReentrancyGuard, Ownable2StepUpgradeable, Paus
     }
 
     /// @notice forwards function call to Mailbox based on ChainId
+    /// @param _chainId The chain ID of the hyperchain where to prove L1->L2 tx status.
+    /// @param _l2TxHash The L2 canonical transaction hash
+    /// @param _l2BatchNumber The L2 batch number where the transaction was processed
+    /// @param _l2MessageIndex The position in the L2 logs Merkle tree of the l2Log that was sent with the message
+    /// @param _l2TxNumberInBatch The L2 transaction number in the batch, in which the log was sent
+    /// @param _merkleProof The Merkle proof of the processing L1 -> L2 transaction
+    /// @param _status The execution status of the L1 -> L2 transaction (true - success & 0 - fail)
+    /// @return Whether the proof is correct and the transaction was actually executed with provided status
+    /// NOTE: It may return `false` for incorrect proof, but it doesn't mean that the L1 -> L2 transaction has an opposite status!
     function proveL1ToL2TransactionStatus(
         uint256 _chainId,
         bytes32 _l2TxHash,

l1-contracts/contracts/state-transition/chain-deps/facets/Mailbox.sol

@@ -36,7 +36,7 @@ contract MailboxFacet is ZkSyncHyperchainBase, IMailbox {
     string public constant override getName = "MailboxFacet";
 
     /// @dev Era's chainID
-    uint256 public immutable ERA_CHAIN_ID;
+    uint256 internal immutable ERA_CHAIN_ID;
 
     constructor(uint256 _eraChainId) {
         ERA_CHAIN_ID = _eraChainId;

l2-contracts/contracts/bridge/L2SharedBridge.sol

@@ -39,10 +39,10 @@ contract L2SharedBridge is IL2SharedBridge, Initializable {
     /// This is non-zero only on Era, and should not be renamed for backward compatibility with the SDKs.
     address public override l1Bridge;
 
-    uint256 public immutable ERA_CHAIN_ID;
-
     /// @dev Contract is expected to be used as proxy implementation.
     /// @dev Disable the initialization to prevent Parity hack.
+    uint256 public immutable ERA_CHAIN_ID;
+
     constructor(uint256 _eraChainId) {
         ERA_CHAIN_ID = _eraChainId;
         _disableInitializers();