Problem

parseEventLogs accepts (Log | RpcLog)[] in its type signature, but never normalizes RpcLog entries before processing them. When logs come directly from a JSON-RPC response (e.g. eth_getLogs), QUANTITY fields like blockNumber, logIndex, transactionIndex, and blockTimestamp are hex-encoded strings (0x...) per the Ethereum JSON-RPC spec.

These raw hex strings propagate into the returned Log objects, causing a runtime type violation: the TypeScript signature promises Log<bigint, number> but consumers receive hex strings at runtime. This can silently break downstream comparisons, arithmetic, and serialization that assumes native types.

Reproduction

const rpcLogs = await fetch(rpcUrl, {
  method: 'POST',
  body: JSON.stringify({
    jsonrpc: '2.0',
    method: 'eth_getLogs',
    params: [{ fromBlock: '0x0', toBlock: 'latest', address: contractAddress }],
    id: 1,
  }),
}).then(r => r.json()).then(r => r.result)

const parsed = parseEventLogs({ abi: myAbi, logs: rpcLogs })
console.log(typeof parsed[0].blockNumber) // "string" — should be "bigint"

Solution

Detect RpcLog inputs via typeof log.blockNumber === 'string' and normalize them through the existing formatLog utility before decoding. This converts hex-encoded QUANTITY fields to their native types (bigint for block numbers/timestamps, number for indices). Already-formatted Log inputs pass through unchanged.

This is the same normalization pattern used throughout viem's action layer (e.g. getBlock, getTransactionReceipt) but was missing from parseEventLogs.

Changes

• src/utils/abi/parseEventLogs.ts: Added formatLog import and RpcLog detection/normalization at the start of the .map() callback. All subsequent references use the normalized log.
• src/utils/abi/parseEventLogs.test.ts: Added test suite covering:
  • Hex-encoded RpcLog fields are correctly formatted to native types
  • Already-formatted Log inputs pass through unchanged (no double-formatting)
  • Mixed RpcLog and Log inputs in the same array

Fixes #4340