zkSync explorer fetcher likely broken: missing solcInput (KeyError downstream) + ContractName casing mismatch

[tamtamchik]

Summary

The zkSync explorer fetcher (_get_contract_from_zksync in diffyscan/utils/explorer.py) returns a contract dict incompatible with downstream code, and has a key-casing inconsistency. zkSync contract verification appears to be broken (surfaced during an audit of the docs vs code).

1. Missing solcInput → KeyError downstream

The fetcher returns (explorer.py ~251-255):

contract = {
    "name": data["ContractName"],
    "sources": json.loads(data["sourceCode"]["sources"]),
    "compiler": data["CompilerVersion"],
}

There is no solcInput key. But downstream, both:

• run_source_diff → diffyscan.py:204: get_solc_sources(contract_code["solcInput"])
• run_bytecode_diff → diffyscan.py:70: solc_input = contract_source_code["solcInput"]

read contract["solcInput"] unconditionally — there is no zkSync-specific branch anywhere in diffyscan.py. A verified zkSync contract reaching this path raises KeyError: 'solcInput'.

2. ContractName casing inconsistency

data = response["request"]
if "contractName" not in data:     # lowercase presence check
    _error_no_source_code_and_exit(contract)
contract = {
    "name": data["ContractName"],  # uppercase read
    "compiler": data["CompilerVersion"],
    ...
}

The presence guard checks lowercase contractName, but the reads use ContractName / CompilerVersion. Depending on the real API casing this either always trips the "not verified / no source" branch, or raises KeyError on the read.

Impact

zkSync source/bytecode verification likely fails for every contract via this path.

Suggested next steps

• Confirm the live zkSync explorer API response shape (key casing; whether it returns standard-json solc input).
• Construct a proper solcInput for the zkSync path (or add a downstream branch), and align the key casing.

Found via a docs-vs-code audit; not yet reproduced against a live zkSync contract.