NomicFoundation

Add or modify a "util" in the Hardhat repo — a small, project-independent command exposed both as a built-in Hardhat task (`hardhat utils <ns> <cmd>`) and through the standalone `hhu <ns> <cmd>` binary, defined once in the `hhu` built-in plugin. Use when adding a new util task or namespace (like `constants zero-address`, `fetch block-number`, `convert pad`), or when a util needs something new such as a flag/option.

Analyzes the Hardhat regression benchmark history (the hardhat-benchmark-results repo's data.js) and recommends how many times each benchmark should run. It reads every commit's individual run times, computes each benchmark's per-commit coefficient of variation, removes outliers, takes the 95th-percentile CV, and sizes run counts for target noise levels (sigma = 3%, 1.5%, 1%, i.e. regression alert limits of 10% / 5% / 3%). Use when asked to right-size benchmark run counts, justify or revisit run counts, assess benchmark variance/noise, or decide whether to add or remove runs after changing the regression alert threshold.

Use when working with Hardhat 3 projects — writing or modifying Solidity tests, TypeScript tests, or any code touching hardhat.config.ts, the `hardhat` import, or `network.create()`. Covers test-layer choice, forge-std cheatcodes, the network connection API, `networkHelpers`, and the compile-then-typecheck workflow. For toolbox-specific guidance (clients, contract calls, assertions), also load the matching `hardhat-toolbox-*` skill.

Use alongside the `hardhat` skill when the project depends on `@nomicfoundation/hardhat-toolbox-mocha-ethers`. Covers the ethers helpers exposed on `network.create()`, contract interaction (`ethers.deployContract`, calling functions, `connect`), TypeChain-typed contract instances, and the chai matchers from `@nomicfoundation/hardhat-ethers-chai-matchers` (`.to.emit`, `.to.be.revertedWith*`, `.to.changeEtherBalance(s)`).

Use alongside the `hardhat` skill when the project depends on `@nomicfoundation/hardhat-toolbox-viem`. Covers the viem clients exposed on `network.create()`, contract interaction (`viem.deployContract`, `read`, `write`, `getContractAt`), and `viem.assertions` (revert / event / balance assertions).

Set up a local Verdaccio environment to test EDR + Hardhat 3 + a third-party repo (e.g. openzeppelin-contracts). Builds EDR with a chosen Rust profile, publishes EDR and Hardhat packages to a local Verdaccio registry, and installs them in the target repo. Use when you need to test local EDR changes in a realistic npm-installed setup.

Update REVM and related crate dependencies (revm, revm-primitives, revm-interpreter, revm-precompile, revm-handler, revm-context, revm-context-interface, revm-database-interface, revm-state, revm-bytecode, revm-inspector, op-revm) to a specific release version. Fetches version information from the REVM GitHub repository at a git tag, updates all Cargo.toml workspace dependencies, fixes compilation errors, and runs quality checks.

Systematically migrate a Hardhat V2 project to Hardhat V3, covering core changes (ESM, declarative config, hooks system, network connections) and the full plugin ecosystem (hardhat-deploy, hardhat-verify, @openzeppelin/hardhat-upgrades, and others), coverage tools, and test migration. Use when upgrading any production Hardhat V2 repository to V3.

Migrate a Solidity project from Foundry to Hardhat 3. Maps `foundry.toml` to `hardhat.config.ts`, converts dependencies and imports, gets compilation and Solidity tests passing, and produces a migration report with feature-parity gaps and a cleanup checklist.

Address reviewer feedback on an open pull request — fetch unresolved review threads, reply within each thread, and commit requested changes. Use whenever responding to PR review comments, addressing review feedback, or working through reviewer threads on the current branch's PR.