Add extra data in /eth/v1/debug/fork_choice

[chong-he]

Issue Addressed

• Extend fork choice debug endpoint with extra data #7829

Additional Info

Querying the endpoint curl -X 'GET' 'http://localhost:5052/eth/v1/debug/fork_choice' | jq yields:

Before:

  {
      "slot": "1033932",
      "block_root": "0xe1b860bbeec083c8edae37025366d3d62ac40bd27e3bd5baf0dfeb3bb74f9d13",
      "parent_root": "0x590d229e47b588449fc68c3f3047ac92e49637b8d2456c5abdaa7a80da2162ec",
      "justified_epoch": "32309",
      "finalized_epoch": "32308",
      "weight": "497146337500000",
      "validity": "valid",
      "execution_block_hash": "0xb7ccfe614cfd3ba54d11a10a5286e2e8365355d7f0bffbc456e5531d93b9b99b"
    }

After:

    {
      "slot": "1056126",
      "block_root": "0x2f4f8155e4c11a621b433570feabb60da6d303ed221e91c41160dde8ef126311",
      "parent_root": "0xde33eb2df97f3e87e1099872cfac19761bbf0379b62ef73afa2688b2fdfcefb5",
      "justified_epoch": "33002",
      "finalized_epoch": "33001",
      "weight": "2252276000000000",
      "validity": "valid",
      "execution_block_hash": "0x3870e095e8a2d9cd7f3e6c1bf26d2e06b071a982d294b774b922b9eea933a54a",
      "extra_data": {
        "target_root": "0x429b73834e076d946645b042cfe218c860c77fa6a0f1a2510a0f3ea5f13c0e83",
        "justified_root": "0xbf4ca2a5062b837822b02c28654535daa31ce465ffa7b7dc3134d68eacacbdff",
        "finalized_root": "0x009ed887bfb16ca18ed24e7463457b3be358b06fd8d8507eb9e46e0121322f09",
        "unrealized_justified_root": "0x429b73834e076d946645b042cfe218c860c77fa6a0f1a2510a0f3ea5f13c0e83",
        "unrealized_finalized_root": "0xbf4ca2a5062b837822b02c28654535daa31ce465ffa7b7dc3134d68eacacbdff",
        "unrealized_justified_epoch": "33003",
        "unrealized_finalized_epoch": "33002",
        "timestamp": "1754886936",
        "execution_status": "valid",
        "best_child": "0x71195e3c4a481d9074fd26ea4833c1a9267d77302690b9f3317b118d65c2c21b",
        "best_descendant": "0x71195e3c4a481d9074fd26ea4833c1a9267d77302690b9f3317b118d65c2c21b"
      }

[chong-he]

I have added most fields mentioned in #7829 , except for balance from the response of Prysm. Initially I thought it is the weight (which is already returned in the main response), but the data shows that weight is not equal to balance most of the time.

This is the field in the source code, which leads to this struct. I only see weight in ProtoNode in Lighthouse code.

Other than that, this PR is ready for review. I am happy to add/remove any fields that are required/not necessary, or rearrange the fields to make it more readable

[chong-he]

This field and best_child and best_descendant are returning numbers without quotes "". I see the response from Prysm is with the quotes, as they convert it to string. So wondering whether I can leave these fields as pure numbers?

[michaelsproul]

Usually quoted numbers are better for compatibility.

For best child and best descendant does Prysm use a numeric index or a block root? To me it seems like a block root would be clearer

[chong-he]

The code is here (also found the definition for balance): https://github.com/OffchainLabs/prysm/blob/develop/beacon-chain/forkchoice/doubly-linked-tree/types.go#L60-L62

I think the *Node refers to the block root?

In Lighthouse, it is defined as Option<usize> (index):

lighthouse/consensus/proto_array/src/proto_array.rs

Line 103 in cfb1f73

pub best_descendant: Option<usize>,

Do we have to change this?

[michaelsproul]

You can convert the index into a block root by looking it up in the array of nodes. E.g. if the index for best child is 5, use the block root of the 5th node as best child

For the balance vs weight, I think the difference is the attestation weight for the single block, vs the weight for that block and all its descendants. I think we can leave out the balance for now because it's a bit more involved to calculate it

[chong-he]

Changed timestamp to String, and best_child and best_descendant to display block_root instead

Thanks!