LP-3691: EVM Developer Improvements

Abstract

LP-3691 introduces developer-focused improvements to the Lux EVM, including the eth_config RPC method (EIP-7910), history expiry tools for efficient node operation, and enhanced sync capabilities. These features simplify node operations, speed up sync times, and provide better introspection into chain configuration.

Motivation

Developers and node operators need better tools to:

Understand Chain Configuration: Query active forks, parameters, and chain ID
Manage Historical Data: Prune old state without losing consensus validity
Speed Up Sync: Bootstrap nodes faster with snapshots and checkpoints
Reduce Storage: Minimize disk usage while maintaining security

Developer Pain Points

Issue	Impact	Solution
Unknown chain config	Incompatible deployments	`eth_config` RPC
Unbounded state growth	2TB+ node storage	History expiry
Slow initial sync	Days to weeks	Snapshot sync
Unclear fork status	Misconfigured clients	Config introspection

Specification

1. eth_config RPC Method (EIP-7910)

New RPC method returning chain configuration:

// Request
{
  "jsonrpc": "2.0",
  "method": "eth_config",
  "params": [],
  "id": 1
}

// Response
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "chainId": "0x1786D",  // 96365 (Lux C-Chain)
    "homesteadBlock": "0x0",
    "eip150Block": "0x0",
    "eip155Block": "0x0",
    "eip158Block": "0x0",
    "byzantiumBlock": "0x0",
    "constantinopleBlock": "0x0",
    "petersburgBlock": "0x0",
    "istanbulBlock": "0x0",
    "berlinBlock": "0x0",
    "londonBlock": "0x0",
    "shanghaiTime": 1710000000,
    "cancunTime": 1720000000,
    "pragueTime": 1730000000,
    "forks": {
      "apricotPhase1": "0x0",
      "apricotPhase2": "0x0",
      "apricotPhase3": "0x0",
      "apricotPhase4": "0x0",
      "apricotPhase5": "0x0",
      "banff": "0x5A0000",
      "cortina": "0x5B0000",
      "durango": "0x5C0000",
      "etna": "0x5D0000",
      "fortuna": "0x5E0000",
      "granite": "0x5F0000"
    },
    "networkId": 96369,
    "networkName": "lux-mainnet"
  }
}

Implementation: geth/internal/ethapi/api.go - Config method

2. History Expiry

Automatic pruning of historical state beyond a configurable horizon:

const (
    // Default history retention (90 days of blocks)
    DefaultHistoryRetention = 90 * 24 * 60 * 60 / 2 // ~3.9M blocks at 2s

    // Minimum retention (7 days)
    MinHistoryRetention = 7 * 24 * 60 * 60 / 2
)

type HistoryConfig struct {
    // Enable history expiry
    Enabled bool `json:"enabled"`

    // Number of blocks to retain
    RetentionBlocks uint64 `json:"retentionBlocks"`

    // Prune interval (blocks between prune operations)
    PruneInterval uint64 `json:"pruneInterval"`
}

CLI Flags:

# Enable history expiry with 30-day retention
luxd --history-expiry.enabled --history-expiry.retention 1296000

# Query expiry status
curl -X POST --data '{"jsonrpc":"2.0","method":"eth_historyStatus","params":[],"id":1}' http://localhost:8545

Implementation: geth/core/blockchain.go - history expiry logic

3. Enhanced Sync Modes

New sync capabilities for faster node bootstrap:

type SyncConfig struct {
    // Sync mode: "full", "snap", "light", "checkpoint"
    Mode string `json:"mode"`

    // Checkpoint for checkpoint sync
    Checkpoint *types.Header `json:"checkpoint,omitempty"`

    // Trusted state root for snap sync
    StateRoot common.Hash `json:"stateRoot,omitempty"`

    // Blob sidecar retention
    BlobRetention uint64 `json:"blobRetention"`
}

Sync Modes:

Mode	Description	Speed	Security
full	Process all blocks from genesis	Slowest	Highest
snap	Download state snapshot, verify headers	Fast	High
checkpoint	Trust checkpoint, sync from there	Fastest	Medium
light	Header-only with proof requests	Instant	Lowest

4. RPC Improvements

Additional RPC methods for better developer experience:

// Get sync status with ETA
eth_syncStatus() → {
  syncing: boolean,
  currentBlock: number,
  highestBlock: number,
  startingBlock: number,
  estimatedTimeRemaining: number // seconds
}

// Get node capabilities
eth_capabilities() → string[]  // ["eth/68", "snap/1", "les/4"]

// Get peer info summary
eth_peerSummary() → {
  total: number,
  inbound: number,
  outbound: number,
  byVersion: { [version: string]: number }
}

// Debug: Get state size at block
debug_stateSize(blockNumber) → {
  accounts: number,
  storage: number,
  codeBytes: number
}

Implementation Status

Feature	EIP	Implementation	Status
eth_config	EIP-7910	`internal/ethapi/api.go`	✅
History expiry	-	`core/blockchain.go`	✅
Snap sync	EIP-4444	`eth/downloader/`	✅
eth_syncStatus	-	`internal/ethapi/api.go`	✅
eth_capabilities	-	`internal/ethapi/api.go`	✅

Test Cases

func TestEthConfig(t *testing.T) {
    client := ethclient.Dial("http://localhost:8545")

    var config map[string]interface{}
    err := client.CallContext(ctx, &config, "eth_config")
    require.NoError(t, err)

    require.Equal(t, "0x17871", config["chainId"])
    require.NotNil(t, config["forks"])
}

func TestHistoryExpiry(t *testing.T) {
    bc := newBlockchain(HistoryConfig{
        Enabled:         true,
        RetentionBlocks: 1000,
        PruneInterval:   100,
    })

    // Add 2000 blocks
    for i := 0; i < 2000; i++ {
        bc.InsertBlock(generateBlock(i))
    }

    // Old blocks should be pruned
    _, err := bc.GetBlockByNumber(100)
    require.Error(t, err) // Block pruned

    _, err = bc.GetBlockByNumber(1500)
    require.NoError(t, err) // Block retained
}

Security Considerations

History Expiry: Does not affect consensus - only historical queries
Checkpoint Sync: Requires trusted checkpoint source
RPC Exposure: New methods should respect auth settings
State Pruning: Carefully validated to never prune needed state

Backwards Compatibility

All new features are additive:

New RPC methods don't affect existing ones
History expiry is opt-in
Sync modes default to current behavior

EVM Developer Improvements