Add ChainId to legacy transactions in RPC responses derived from signature

[Copilot]

Description

Fixes legacy transaction RPC responses to include the chainId field when it can be derived from the transaction signature, even when transaction.ChainId is null.

According to the Ethereum JSON-RPC specification and Hive test expectations, legacy transactions (type 0x0) should include the chainId field in RPC responses when the transaction is signed with EIP-155 (where chainId is encoded in the V value of the signature).

Changes

Core Implementation

Modified LegacyTransactionForRpc constructor to populate ChainId from the signature when transaction.ChainId is null:

// Before: ChainId was only set from transaction.ChainId
ChainId = transaction.ChainId;

// After: Falls back to signature.ChainId if transaction.ChainId is null
ChainId = transaction.ChainId ?? signature.ChainId;

The Signature class already has logic to extract chainId from the V value for EIP-155 transactions:

• For pre-EIP-155 transactions (V < 35): chainId is null
• For EIP-155 transactions (V >= 35): chainId = (V + (V % 2) - 36) / 2

Testing

• Added tests to verify chainId is correctly populated from signature when transaction.ChainId is null
• Added test to verify transaction.ChainId takes precedence when explicitly set
• Updated existing test expectations to include chainId in legacy transaction RPC responses

Example

For a legacy transaction with V = 0x18e5bb3abd109f (from the Hive test):

{
  "type": "0x0",
  "nonce": "0x9a",
  "chainId": "0xc72dd9d5e883e",  // Now correctly included
  "v": "0x18e5bb3abd109f",
  "r": "0x551fe45ccebb0318196e31dbc60da87c43dc60b8fb01afb3286693fa09878730",
  "s": "0x40d33e9afecfe1516b045d61a3272bddbc83f482a7f2c749311248b50fe62e81"
}

Impact

This change ensures Nethermind's RPC responses are compliant with Ethereum JSON-RPC specifications and pass Hive conformance tests for legacy transactions.

Resolves issue where Hive expected chainId to be returned for legacy transactions.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>ChainID for legacy transactions in RPC</issue_title>
<issue_description>```

{"jsonrpc":"2.0","id":1,"method":"eth_getBlockByNumber","params":["safe",true]}
<< {"jsonrpc":"2.0","result":{"difficulty":"0x0","extraData":"0x","gasLimit":"0x47e7c40","gasUsed":"0x54a92","hash":"0xaf51811799f22260e5b4e1f95504dae760505f102dcb2e9ca7d897d8a40124a1","logsBloom":"0x00000000008000000000000000000040000000000000000000000000800000000000000008000000000000000000000000000000000000000000000000000000000000000000000000004000000000020200000000000000000000000000002000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000000000000000000000000000009000000000000000000000002000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000","miner":"0x0000000000000000000000000000000000000000","mixHash":"0x0000000000000000000000000000000000000000000000000000000000000000","nonce":"0x0000000000000000","number":"0x2d","parentHash":"0xab97b6b403066d2f4b270171bd532cc489510c1e07df609718dfc875cace60f1","receiptsRoot":"0x2c86b2791cdd088d3c3e9d6225f71724d3e8c67bdd13cd6208831058cee1043f","sha3Uncles":"0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347","size":"0x633","stateRoot":"0x67b58d6bd3c58396b464d3ae8f8a7e2e8ebf912b203ece9bf8a89063a79265bd","timestamp":"0x1c2","baseFeePerGas":"0x5763d64","transactions":[{"type":"0x0","nonce":"0x9a","to":null,"from":"0x7435ed30a8b4aeb0877cef0c6e8cffe834eb865f","value":"0x0","input":"0x600d380380600d6000396000f336156009575f355f555b305f525f5460205260405ff3","gasPrice":"0x5763d65","v":"0x18e5bb3abd109f","r":"0x551fe45ccebb0318196e31dbc60da87c43dc60b8fb01afb3286693fa09878730","s":"0x40d33e9afecfe1516b045d61a3272bddbc83f482a7f2c749311248b50fe62e81","hash":"0x2fbbd036996c7487316c92b9e5798edb98fd57f32a6c1075e904a734821e1cd2","transactionIndex":"0x0","blockHash":"0xaf51811799f22260e5b4e1f95504dae760505f102dcb2e9ca7d897d8a40124a1","blockNumber":"0x2d","gas":"0x11c32"},{"type":"0x4","authorizationList":[{"chainId":"0xc72dd9d5e883e","nonce":"0x0","address":"0x58f8fe237b593c19546e1e758a2544561d04bfe0","yParity":"0x1","s":"0x1d1225f76d6faac3d904c0635193e83d3867c101b2e6f6c9bb7b1fdeeed923ab","r":"0xec6caeb1b7071f1b3ae36aeaa7bf0eaecb8e006e83b3e50d792870ea95af4c59"}],"maxPriorityFeePerGas":"0x1","maxFeePerGas":"0x5763d65","accessList":[],"yParity":"0x1","chainId":"0xc72dd9d5e883e","nonce":"0x9b","to":"0x0000000000000000000000000000000000000000","from":"0x7435ed30a8b4aeb0877cef0c6e8cffe834eb865f","value":"0x0","input":"0x","gasPrice":"0x5763d65","v":"0x1","r":"0x8ae3402e4f63751c895532b94aee0f7b6b8ff5d0b0a689f6d63b3dbd19d69059","s":"0x2e63e4d140b0d282d56289b34f3df82cbcb2f3aa385f5438a423584fe0c2b467","hash":"0x16f6724ad864e7664c367893cae3e176d362bea3a47495cec3b246555a7228da","transactionIndex":"0x1","blockHash":"0xaf51811799f22260e5b4e1f95504dae760505f102dcb2e9ca7d897d8a40124a1","blockNumber":"0x2d","gas":"0xb3b0"},{"type":"0x0","nonce":"0x9c","to":"0xeda8645ba6948855e3b3cd596bbb07596d59c603","from":"0x7435ed30a8b4aeb0877cef0c6e8cffe834eb865f","value":"0x0","input":"0x696e766f6b6564","gasPrice":"0x5763d65","v":"0x18e5bb3abd10a0","r":"0xfea7e18c82a1270f142572533bc2e6e33d6d41a3f1303403dd0a90dd7a4f35d","s":"0x4a4ab6c5bb4c31c3a5f8991ae45bad2303c45923404571f7b4c66adbd03b7936","hash":"0xddf234c5f149d2d1a4d01276d42e38a6234bfa7b987c49ba889b028b429aac8f","transactionIndex":"0x2","blockHash":"0xaf51811799f22260e5b4e1f95504dae760505f102dcb2e9ca7d897d8a40124a1","blockNumber":"0x2d","gas":"0x11170"},{"type":"0x2","maxPriorityFeePerGas":"0x2","maxFeePerGas":"0x5763d65","accessList":[],"yParity":"0x1","chainId":"0xc72dd9d5e883e","nonce":"0x9d","to":"0x00000961ef480eb55e80d19ad83579a64c007002","from":"0x7435ed30a8b4aeb0877cef0c6e8cffe834eb865f","value":"0x3b9aca00","input":"0xb917cfdc0d25b72d55cf94db328e1629b7f4fde2c30cdacf873b664416f76a0c7f7cc50c9f72a3cb84be88144cde91250000000000000d80","gasPrice":"0x5763d65","v":"0x1","r":"0x5f8b300cf80f7fb7e511460fa1a803278b47223f2c0a82857c5c0e5f7c900d23","s":"0x290bf2495235a106352786403ed937df8385a2356472569020fd952913690ec9","hash":"0x3d3d02e1bdc39a6eab20f7b44ed299ca61eb1d642806bfa07e3a7ee8edd700e5","transactionIndex":"0x3","blockHash":"0xaf51811799f22260e5b4e1f95504dae760505f102dcb2e9ca7d897d8a40124a1","blockNumber":"0x2d","gas":"0x249f0"},{"type":"0x1","accessList":[{"address":"0x7dcd17433742f4c0ca53122ab541d0ba67fc27df","storageKeys":["0x0000000000000000000000000000000000000000000000000000000000000000","0xe8481f0a1ea7b2528784efff1d1b33cbd66ac97ebe2ae35c7997cacb2863430b"]}],"yParity":"0x0","chainId":"0xc72dd9d5e883e","nonce":"0x9e","to":"0x7dcd17433742f4c0ca53122ab541d0ba67fc27df","from":"0x7435ed30a8b4aeb0877cef0c6e8cffe834eb865f","value":"0x2","input":"0x6b3b937565afc29f656d6974","gasPrice":"0x5763d65","v":"0x0","r":"0x84f8b48ac6fbf39054c7794e6ff4e1...

Fixes #9372

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.