rpcwright 🔧

A wright is a maker — a shipwright builds ships, a playwright builds plays. A rpcwright builds (and proves) Ethereum JSON-RPC.

rpcwright is an agent skill that teaches an AI agent how to implement and conformance-test a change to the Ethereum execution-layer JSON-RPC API — across the four repos that have to agree:

The one-line behavior change is easy. The hard part is the build/test plumbing and the dozen places a silent failure hides — a green hive run that executed zero tests, a fixture that passes validation only because the param was still "required", a harness quietly testing the upstream image instead of your change. This skill encodes the exact commands and those gotchas so future sessions don't rediscover them the slow way.

What's inside

• SKILL.md: scope, reference selection, workflow, and validation requirements.
• references/go-ethereum.md — build, test, RPC method & optional-parameter patterns, in-process RPC test harness.
• references/execution-apis.md — OpenRPC YAML, specgen/openrpc.json, speccheck, and the required semantics.
• references/testgen.md — rpctestgen, make fill, the .io format, generating fixtures with a local client, determinism.
• references/hive.md — the rpc-compat simulator, local fixtures, building clients from source, client-files, the --sim.limit trap, reading results.
• references/clients.md: handler locations, registration, build examples, and contribution checks for six clients.
• references/hivechain.md: chain generation, fork configuration, and behavior surveys.
• references/tracers.md: named-tracer schemas and validation.
• references/gotchas.md — the full catalog.
• references/worked-example.md — a complete change end to end (default an omitted block param to latest), including a real cross-client bug found and fixed.

Install

Claude Code and Codex both read the same format — a directory with a SKILL.md — so one copy serves both. Only the directory each one scans differs:

Claude Code plugin (no clone)

/plugin marketplace add MysticRyuujin/rpcwright
/plugin install rpcwright@rpcwright

Manual (personal skill)

Clone once, then symlink it into the tools you use. Both follow a symlinked skill directory, so a single git pull updates every tool:

git clone https://github.com/MysticRyuujin/rpcwright.git
mkdir -p ~/.claude/skills ~/.agents/skills
ln -s "$PWD/rpcwright" ~/.claude/skills/rpcwright   # Claude Code
ln -s "$PWD/rpcwright" ~/.agents/skills/rpcwright   # Codex

Either tool discovers the skill from its SKILL.md frontmatter and loads it when a task involves the Ethereum JSON-RPC API, execution-apis, rpctestgen/testgen, .io fixtures, speccheck, openrpc.json, or hive rpc-compat.

AGENTS.md, CLAUDE.md, and llms.txt are symlinks to SKILL.md, so a repo that vendors rpcwright at its root also picks it up as plain project instructions.

Scope

The skill covers changes and reviews across six execution clients, execution-apis, testgen, and Hive. Use only the stages required by the task. Confirm paths, toolchain pins, and historical observations against the selected revisions.

License

MIT — see LICENSE.

{
  "name": "rpcwright",
  "owner": {
    "name": "MysticRyuujin",
    "url": "https://github.com/MysticRyuujin"
  },
  "metadata": {
    "description": "Ethereum JSON-RPC standards engineering skill.",
    "version": "1.1.0"
  },
  "plugins": [
    {
      "name": "rpcwright",
      "source": "./",
      "version": "1.1.0",
      "description": "Engineer and conformance-test Ethereum JSON-RPC (execution-apis) changes across EL clients.",
      "author": {
        "name": "MysticRyuujin"
      }
    }
  ]
}