Support for single-file contracts

[failingtwice]

Currently, Diffyscan fails when the contract is a single file (no deps, imports) because Etherscan does not return the filepath. Perhaps, we will have to search the repo to find the file.

[Alexvozhak]

Diffyscan fails on single‑file (“flatten”) verifications – cannot fetch *.sol, aborts execution (e.g. EasyTrack's contracts)

Problem

When a contract is verified on Etherscan in single‑file mode (developer uploads flattened Solidity),
solcInput.sources that Etherscan returns contains one key – the monolith’s basename without .sol.

single‑file verification 0x9A2029735Bd14C8b17fd03FE05D5F04F7AF797c2:

multi-file verification 0xbE861866E2Ca8f401e2b51b2cFb36A61B0Bf6840:

diffyscan uses that key (e.g. EasyTrack) verbatim and queries GitHub:

The correct URL should be:

💡 Possible solutions / improvement ideas

• Option A – local flatten compilation

  • Detect single‑file verification and run
    brownie compile → brownie flatten <Entry>.sol to reproduce the same monolith locally.
  • How to know which files to flatten
    • Parse the comment headers in the Etherscan monolith
      (// contracts/…, // dependencies/…) to rebuild the import list, or
    • Let the user supply that list explicitly in the diffyscan config.

• Option B – graceful fallback

  • Add a switch (skip_source_diff: true or CLI --no-source-diff) that disables the per‑line source comparison when flattened input is detected, but still performs bytecode verification.
    This keeps useful checks even when source diff is impossible.

Draft PR with added bytecode verification for Easytrack