## PR Summary

PR Summary

Medium Risk
Changes how external Etherscan requests are formed (endpoint + required chainid), which can break contract-source fetching if env vars or query formatting are wrong; otherwise the change set is small.

Overview
Updates the Etherscan integration to call the mandatory v2 API endpoint (/v2/api) and includes a configurable chainid (via ETHERSCAN_CHAIN_ID, defaulting to 1) in all requests.

Refactors query construction to ensure all parameters are stringified and adds a safer default for missing APIKEY_ETHERSCAN. Improves etherscanParse failures by surfacing the underlying Etherscan error message/result in the thrown error string.

^{Written by Cursor Bugbot for commit 855cad55035b816e517c1dd47d39a67348dc8097. Configure here.}

Originally posted by @cursor[bot] in https://github.com/duneanalytics/evm.codes/issues/398#issuecomment-3922130888

The payload does not name files or tests. Start by locating the Etherscan integration and reviewing how its endpoint, query parameters, API key, and parsing errors are handled. Done means requests use the v2 API with a configurable chain ID, missing keys are handled safely, and Etherscan error details remain visible.