diff --git a/packages/protocol/contracts/L1/TaikoData.sol b/packages/protocol/contracts/L1/TaikoData.sol
index 2c816af177..a9b0adc6ed 100644
--- a/packages/protocol/contracts/L1/TaikoData.sol
+++ b/packages/protocol/contracts/L1/TaikoData.sol
@@ -163,7 +163,7 @@ library TaikoData {
         mapping(
             uint64 blockId_mod_blockRingBufferSize
                 => mapping(uint32 transitionId => TransitionState ts)
-        ) transitions;
+            ) transitions;
         // Ring buffer for Ether deposits
         bytes32 __reserve1;
         SlotA slotA; // slot 5
diff --git a/packages/protocol/contracts/bridge/Bridge.sol b/packages/protocol/contracts/bridge/Bridge.sol
index b27816526e..a4122e2b87 100644
--- a/packages/protocol/contracts/bridge/Bridge.sol
+++ b/packages/protocol/contracts/bridge/Bridge.sol
@@ -216,13 +216,20 @@ contract Bridge is EssentialContract, IBridge {
         bytes calldata _proof
     )
         external
-        sameChain(_message.destChainId)
-        diffChain(_message.srcChainId)
         whenNotPaused
         nonReentrant
+        returns (IBridge.Status)
     {
         uint256 gasStart = gasleft();
 
+        // same as `sameChain(_message.destChainId)` but without stack-too-deep
+        if (_message.destChainId != block.chainid) revert B_INVALID_CHAINID();
+
+        // same as `diffChain(_message.srcChainId)` but without stack-too-deep
+        if (_message.srcChainId == 0 || _message.srcChainId == block.chainid) {
+            revert B_INVALID_CHAINID();
+        }
+
         // If the gas limit is set to zero, only the owner can process the message.
         if (_message.gasLimit == 0 && msg.sender != _message.destOwner) {
             revert B_PERMISSION_DENIED();
@@ -281,6 +288,7 @@ contract Bridge is EssentialContract, IBridge {
 
         _updateMessageStatus(msgHash, stats.status);
         emit MessageProcessed(msgHash, _message, stats);
+        return stats.status;
     }
 
     /// @inheritdoc IBridge
diff --git a/packages/protocol/contracts/bridge/IBridge.sol b/packages/protocol/contracts/bridge/IBridge.sol
index 0e2ad57bfd..2ab3830833 100644
--- a/packages/protocol/contracts/bridge/IBridge.sol
+++ b/packages/protocol/contracts/bridge/IBridge.sol
@@ -90,7 +90,13 @@ interface IBridge {
     /// needed.
     /// @param _message The message to be processed.
     /// @param _proof The merkle inclusion proof.
-    function processMessage(Message calldata _message, bytes calldata _proof) external;
+    /// @return The messsage's status after processing.
+    function processMessage(
+        Message calldata _message,
+        bytes calldata _proof
+    )
+        external
+        returns (Status);
 
     /// @notice Retries to invoke the messageCall after releasing associated
     /// Ether and tokens.
diff --git a/packages/protocol/script/DeployERC20Airdrop.s.sol b/packages/protocol/script/DeployERC20Airdrop.s.sol
index 70d0f7f3d4..cd640a0239 100644
--- a/packages/protocol/script/DeployERC20Airdrop.s.sol
+++ b/packages/protocol/script/DeployERC20Airdrop.s.sol
@@ -37,7 +37,7 @@ contract DeployERC20Airdrop is DeployCapability {
                 impl: address(new ERC20Airdrop()),
                 data: abi.encodeCall(
                     ERC20Airdrop.init, (address(0), 0, 0, bytes32(0), bridgedTko, vaultAddress)
-                )
+                    )
             })
         );
 
diff --git a/packages/protocol/script/DeployOnL1.s.sol b/packages/protocol/script/DeployOnL1.s.sol
index 751379e463..fe0577c4d5 100644
--- a/packages/protocol/script/DeployOnL1.s.sol
+++ b/packages/protocol/script/DeployOnL1.s.sol
@@ -152,7 +152,7 @@ contract DeployOnL1 is DeployCapability {
                 impl: address(new TaikoToken()),
                 data: abi.encodeCall(
                     TaikoToken.init, (owner, vm.envAddress("TAIKO_TOKEN_PREMINT_RECIPIENT"))
-                ),
+                    ),
                 registerTo: sharedAddressManager
             });
         }
@@ -263,7 +263,7 @@ contract DeployOnL1 is DeployCapability {
                     vm.envBytes32("L2_GENESIS_HASH"),
                     vm.envBool("PAUSE_TAIKO_L1")
                 )
-            ),
+                ),
             registerTo: rollupAddressManager
         });
 
@@ -330,7 +330,7 @@ contract DeployOnL1 is DeployCapability {
             impl: automateDcapV3AttestationImpl,
             data: abi.encodeCall(
                 AutomataDcapV3Attestation.init, (owner, address(sigVerifyLib), address(pemCertChainLib))
-            ),
+                ),
             registerTo: rollupAddressManager
         });
 
diff --git a/packages/protocol/test/L2/TaikoL2.t.sol b/packages/protocol/test/L2/TaikoL2.t.sol
index 3665c3cf43..eadb14a6f3 100644
--- a/packages/protocol/test/L2/TaikoL2.t.sol
+++ b/packages/protocol/test/L2/TaikoL2.t.sol
@@ -49,7 +49,7 @@ contract TestTaikoL2 is TaikoTest {
                     impl: address(new TaikoL2EIP1559Configurable()),
                     data: abi.encodeCall(
                         TaikoL2.init, (address(0), addressManager, l1ChainId, gasExcess)
-                    ),
+                        ),
                     registerTo: addressManager
                 })
             )
diff --git a/packages/protocol/test/L2/TaikoL2NoFeeCheck.t.sol b/packages/protocol/test/L2/TaikoL2NoFeeCheck.t.sol
index 6a10e25d6c..8b21fbaf56 100644
--- a/packages/protocol/test/L2/TaikoL2NoFeeCheck.t.sol
+++ b/packages/protocol/test/L2/TaikoL2NoFeeCheck.t.sol
@@ -49,7 +49,7 @@ contract TestTaikoL2NoFeeCheck is TaikoTest {
                     impl: address(new SkipBasefeeCheckL2()),
                     data: abi.encodeCall(
                         TaikoL2.init, (address(0), addressManager, l1ChainId, gasExcess)
-                    ),
+                        ),
                     registerTo: addressManager
                 })
             )
diff --git a/packages/protocol/test/automata-attestation/common/AttestationBase.t.sol b/packages/protocol/test/automata-attestation/common/AttestationBase.t.sol
index 453d7d6647..4133197796 100644
--- a/packages/protocol/test/automata-attestation/common/AttestationBase.t.sol
+++ b/packages/protocol/test/automata-attestation/common/AttestationBase.t.sol
@@ -61,7 +61,7 @@ contract AttestationBase is Test, DcapTestUtils, V3QuoteParseUtils {
                 data: abi.encodeCall(
                     AutomataDcapV3Attestation.init,
                     (admin, address(sigVerifyLib), address(pemCertChainLib))
-                )
+                    )
             })
         );
 
diff --git a/packages/protocol/test/bridge/Bridge.t.sol b/packages/protocol/test/bridge/Bridge.t.sol
index 0cf597e457..33caf89b67 100644
--- a/packages/protocol/test/bridge/Bridge.t.sol
+++ b/packages/protocol/test/bridge/Bridge.t.sol
@@ -93,7 +93,7 @@ contract BridgeTest is TaikoTest {
                     impl: address(new DelegateOwner()),
                     data: abi.encodeCall(
                         DelegateOwner.init, (mockDAO, address(addressManager), l1ChainId)
-                    )
+                        )
                 })
             )
         );
diff --git a/packages/protocol/test/team/airdrop/ERC20Airdrop.t.sol b/packages/protocol/test/team/airdrop/ERC20Airdrop.t.sol
index ac33e31935..1222a7cf9e 100644
--- a/packages/protocol/test/team/airdrop/ERC20Airdrop.t.sol
+++ b/packages/protocol/test/team/airdrop/ERC20Airdrop.t.sol
@@ -102,7 +102,7 @@ contract TestERC20Airdrop is TaikoTest {
                 data: abi.encodeCall(
                     BridgedERC20.init,
                     (address(0), address(addressManager), randAddress(), 100, 18, "TKO", "Taiko Token")
-                )
+                    )
             })
         );
 
@@ -129,7 +129,7 @@ contract TestERC20Airdrop is TaikoTest {
                 data: abi.encodeCall(
                     ERC20Airdrop.init,
                     (address(0), claimStart, claimEnd, merkleRoot, address(token), address(vault))
-                )
+                    )
             })
         );
 
diff --git a/packages/protocol/test/tokenvault/BridgedERC20.t.sol b/packages/protocol/test/tokenvault/BridgedERC20.t.sol
index 80470c7064..6c92727d8c 100644
--- a/packages/protocol/test/tokenvault/BridgedERC20.t.sol
+++ b/packages/protocol/test/tokenvault/BridgedERC20.t.sol
@@ -131,7 +131,7 @@ contract TestBridgedERC20 is TaikoTest {
                 data: abi.encodeCall(
                     BridgedERC20.init,
                     (owner, address(manager), srcToken, srcChainId, srcDecimals, name, name)
-                ),
+                    ),
                 registerTo: manager
             })
         );
diff --git a/packages/protocol/test/tokenvault/ERC20Vault.t.sol b/packages/protocol/test/tokenvault/ERC20Vault.t.sol
index 1f0fb5908f..e6e0749af6 100644
--- a/packages/protocol/test/tokenvault/ERC20Vault.t.sol
+++ b/packages/protocol/test/tokenvault/ERC20Vault.t.sol
@@ -177,7 +177,7 @@ contract TestERC20Vault is TaikoTest {
                 data: abi.encodeCall(
                     BridgedERC20.init,
                     (address(0), address(addressManager), randAddress(), 100, 18, "USDC", "USDC coin")
-                )
+                    )
             })
         );
 
@@ -188,7 +188,7 @@ contract TestERC20Vault is TaikoTest {
                 data: abi.encodeCall(
                     BridgedERC20.init,
                     (address(0), address(addressManager), randAddress(), 100, 18, "USDT", "USDT coin")
-                )
+                    )
             })
         );
 
@@ -207,7 +207,7 @@ contract TestERC20Vault is TaikoTest {
                         "stETH",
                         "Lido Staked ETH"
                     )
-                )
+                    )
             })
         );
         vm.stopPrank();
diff --git a/packages/protocol/test/verifiers/RiscZeroVerifier.t.sol b/packages/protocol/test/verifiers/RiscZeroVerifier.t.sol
index 75eb16dd2d..77c719d8a2 100644
--- a/packages/protocol/test/verifiers/RiscZeroVerifier.t.sol
+++ b/packages/protocol/test/verifiers/RiscZeroVerifier.t.sol
@@ -48,7 +48,7 @@ contract TestRiscZeroVerifier is TaikoL1TestBase {
                 data: abi.encodeCall(
                     RiscZeroVerifier.init,
                     (address(0), address(addressManager), address(riscZeroRemoteVerifier))
-                )
+                    )
             })
         );