feat: add Fe language support for smart contract verification

[kuzdogan]

Summary

• New language: Fe (argotorg/fe) — Rust-inspired EVM smart contract language with CLI-only compiler
• Compiler wrapper (feCompiler.ts): downloads Fe binary per-version, scaffolds ingot project structure (fe.toml + src/), runs fe build, reads out/*.bin/out/*.runtime.bin
• FeCompilation class: extends AbstractCompilation; AuxdataStyle.FE (no CBOR metadata → always partial match); no ABI/immutables/libraries
• Server pipeline: FeLocal compiler, Piscina worker support, compilation.ts and database-util.ts Fe cases
• API middleware (validateAndNormalizeFeInput): normalizes source keys to src/ prefix, validates contractIdentifier format (src/path.fe:Name required)
• OpenAPI spec updated with Fe language, examples, and contractIdentifier format docs
• Tests: FeCompilation.spec.ts (6 unit tests), FeVerification.spec.ts (3 verification tests on local hardhat), verify.fe.spec.ts (2 server e2e tests)
• Pre-commit hook (husky + lint-staged): runs ESLint and Prettier on all staged files before every commit. Added to ensure AI agents write correctly styled code — a pre-commit hook was chosen over a Claude-specific instruction so the enforcement applies globally to all contributors, not just Claude.

API usage

Single-file:

POST /v2/verify/{chainId}/{address}
{
  "compilerVersion": "26.0.0-alpha.10",
  "contractIdentifier": "src/lib.fe:Counter",
  "stdJsonInput": {
    "language": "Fe",
    "sources": {
      "src/lib.fe": { "content": "pub contract Counter { ... }" }
    }
  }
}

Multi-file ingot (contract in non-lib.fe file):

{
  "contractIdentifier": "src/counter.fe:Counter",
  "stdJsonInput": {
    "language": "Fe",
    "sources": {
      "src/lib.fe": { "content": "use ingot::counter::Counter" },
      "src/counter.fe": { "content": "pub contract Counter { ... }" }
    }
  }
}

Sources without src/ prefix are automatically normalized. Match is always partial (Fe emits no CBOR metadata hash).

Test plan

• cd packages/lib-sourcify && npm test — 150 tests passing (includes 6 FeCompilation + 3 FeVerification)
• cd services/server && npm run test-local — full integration suite
• Manual: POST to /v2/verify with a deployed Fe contract

TODOs

• Add Fe Support in repo.sourcify.dev #2693
• Add Fe verification docs

🤖 Generated with Claude Code

[kuzdogan]

How a Fe contract is stored in compiled_contracts

Fe is a new compilation type with some workarounds in how it plugs into Sourcify's existing framework (no official std-JSON interface, no CBOR metadata, no ABI). Since this is the first language we add that lacks most of the fields Solidity/Vyper produce, I wanted to highlight exactly how these values get saved in compiled_contracts.

compiled_contracts row:

Column	Value	Description
language	"fe"	Lowercased from "Fe"
compiler	"fe"	Fe CLI compiler
version	"26.0.0-alpha.10"	Compiler version as passed in the request
name	"Counter"	Contract name from contractIdentifier
fully_qualified_name	"src/lib.fe:Counter"	Full path:name from contractIdentifier
compiler_settings	{}	Fe alpha has no configurable settings
compilation_artifacts	{"abi": null, "userdoc": null, "devdoc": null, "storageLayout": null, "transientStorageLayout": null, "sources": null}	Fe does not emit ABI, NatSpec, storage layouts, or source IDs
creation_code_artifacts	{"sourceMap": null, "linkReferences": null, "cborAuxdata": {}}	Fe emits no source maps, has no library linking, and embeds no CBOR metadata
runtime_code_artifacts	{"sourceMap": null, "linkReferences": null, "immutableReferences": null, "cborAuxdata": {}}	Same as creation, plus no immutables

Match type: always "match" (partial) for both creation and runtime. Fe embeds no CBOR metadata in its bytecode, so there is no metadata hash to achieve an exact/perfect match.

All of the above is verified by "should store and return correct Fe-specific fields after verification" in services/server/test/integration/apiv2/verification/verify.fe.spec.ts, which checks every field in this table through two layers:

1. API response — GET /v2/contract/:chainId/:address?fields=compilation,abi,metadata,storageLayout,sources,creationBytecode,runtimeBytecode
2. Direct DB query — raw compiled_contracts row via serverFixture.sourcifyDatabase

[cburgdorf]

Very nice! I'll prioritize a few things so that we can close some gaps (Most importantly the missing JSON ABI)

[manuelwedler]

Nice! Much more straight forward than I thought.

No major issues with the PR. Just some improvements that could be done.

Also, if we can have the ABI support by next week, I would wait for it to merge this PR.

[manuelwedler]

Not part of this PR, but we should add a docs page for Fe support and especially describe how the json input should be created for a Fe contract.

[kuzdogan]

We don't have docs pages for other languages. Isn't the example here enough?

[manuelwedler]

yeah, probably it's enough. Some note somewhere that we support Fe would still be good. We list languages on the intro page, maybe just add it there.

[kuzdogan]

The Blockscout scraping test is failing which will be removed in #2672

[manuelwedler]

@kuzdogan lib-sourcify tests also fail:

@ethereum-sourcify/lib-sourcify:  Exception during run: test/Compilation/FeCompilation.spec.ts(22,9): error TS2345: Argument of type '{ language: "Fe"; sources: { "src/lib.fe": { content: string; }; }; }' is not assignable to parameter of type 'FeJsonInput'.
@ethereum-sourcify/lib-sourcify:   Property 'settings' is missing in type '{ language: "Fe"; sources: { "src/lib.fe": { content: string; }; }; }' but required in type 'FeJsonInput'.
@ethereum-sourcify/lib-sourcify: test/Compilation/FeCompilation.spec.ts(74,9): error TS2345: Argument of type '{ language: "Fe"; sources: { "src/lib.fe": { content: string; }; }; }' is not assignable to parameter of type 'FeJsonInput'.
@ethereum-sourcify/lib-sourcify:   Property 'settings' is missing in type '{ language: "Fe"; sources: { "src/lib.fe": { content: string; }; }; }' but required in type 'FeJsonInput'.
@ethereum-sourcify/lib-sourcify: test/Compilation/FeCompilation.spec.ts(109,9): error TS2345: Argument of type '{ language: "Fe"; sources: { 'src/lib.fe': { content: string; }; 'src/counter.fe': { content: string; }; }; }' is not assignable to parameter of type 'FeJsonInput'.
@ethereum-sourcify/lib-sourcify:   Property 'settings' is missing in type '{ language: "Fe"; sources: { 'src/lib.fe': { content: string; }; 'src/counter.fe': { content: string; }; }; }' but required in type 'FeJsonInput'.

[kuzdogan]

@manuelwedler fixed

[manuelwedler]

Looks good to me! thanks for the changes.

@cburgdorf What's the status on the ABI output? Would still prefer to have it before a Sourcify release of this.

[cburgdorf]

What's the status on the ABI output?

It was merged and will be included in the next release. I'm currently off but I can try to coordinate with the team to cut a new alpha release so you can test out the integration.

[cburgdorf]

You can run feup to get the latest version which has json abi support.

$ fe new foobar
Created ingot at /somepath/foobar
cburgdorf at hackbot in /somepath
$ cd foobar/
cburgdorf at hackbot in /somepath/foobar
$ fe build
Wrote /somepath/foobar/out/Counter.bin
Wrote /somepath/foobar/out/Counter.runtime.bin
Wrote /somepath/foobar/out/Counter.abi.json
cburgdorf at hackbot in /somepath/foobar
$ cat /somepath/foobar/out/Counter.abi.json
[
  {
    "type": "constructor",
    "inputs": [],
    "stateMutability": "nonpayable"
  },
  {
    "type": "function",
    "name": "increment",
    "inputs": [],
    "outputs": [],
    "stateMutability": "nonpayable"
  },
  {
    "type": "function",
    "name": "get",
    "inputs": [],
    "outputs": [
      {
        "name": "",
        "type": "uint256"
      }
    ],
    "stateMutability": "view"
  }
]

[manuelwedler]

You can run feup to get the latest version which has json abi support.

Awesome! Thanks for this!

@kuzdogan let's update this PR and make the new release the minimum supported Fe version. We can also remove the assumption that abi can be null from the code.