What is rigor-ffi-plugin-author?

A workflow for assessing and, when needed, creating a Rigor add-on for Ruby gems that use FFI, a way for Ruby code to call libraries written in other languages. It first checks whether Rigor already supports the gem.

Use it to assess a Ruby FFI gem, decide whether a separate add-on is needed, and author that add-on when the wrapper has one of the documented binding problems.

It prevents unnecessary add-ons when existing support is enough and focuses work on FFI wrappers that remain untyped or uncertain.

How rigortype/rigor configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to rigortype/rigor. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/rigortype/rigor/master/.claude/skills/rigor-ffi-plugin-author/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/rigortype/rigor

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/rigortype/rigor/rigor-ffi-plugin-author/github.svg)](https://agentmods.dev/skills/rigortype/rigor/rigor-ffi-plugin-author)

Your own site

<a href="https://agentmods.dev/skills/rigortype/rigor/rigor-ffi-plugin-author"><img src="https://agentmods.dev/badge/skills/rigortype/rigor/rigor-ffi-plugin-author/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/rigortype/rigor/rigor-ffi-plugin-author"><img src="https://agentmods.dev/badge/skills/rigortype/rigor/rigor-ffi-plugin-author.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 4,004 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00059	$0.04004
Opus 5.5	$0.00024	$0.01602
Sonnet 5.5	$0.00012	$0.00801
Haiku 4.5	$0.00006	$0.00400

Measured 11d ago against content hash fdabff733eea, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

rigor-ffi-plugin-author scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/rigor-ffi-plugin-author/SKILL.md · 334 lines

How it starts

The opening of the file, as written. The whole thing — 334 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Rigor FFI Plugin Author

Sub-plugin for FFI-binding gems. Starts with an assessment phase that will talk you out of authoring a plugin if core rigor-ffi already covers the gem — that's the point. Plugins only exist where the four binding-recovery hazards documented in ADR-30 appear.

Phase 0 — When to trigger this SKILL

Trigger when the user wants to type FFI bindings on a gem that isn't already one of the four bundled consumers (rigor-rbnacl, rigor-ethon, rigor-ffi-rzmq, rigor-sassc). Typical asks:

"Our internal libacme Ruby gem wraps libacme via FFI; the wrapper class methods all type as Dynamic[Top]."
"Add a Rigor plugin for OSS gem X that uses the ffi gem."
"The ffx translator complains about our binding file — can Rigor catch this statically?"

Do NOT trigger for:

Edits to an existing bundled rigor-rbnacl / rigor-ethon / rigor-ffi-rzmq / rigor-sassc — use the general rigor-plugin-author SKILL or treat as ordinary edit work.
Core rigor-ffi engine changes (the BindingRecognizer extension point, the typedef-nominal heuristic, the ffx.unsupported-* diagnostic family) — those are core development under lib/rigor/, not plugin authoring.
Hand-written C extensions (rb_define_method in ext/*.c) — no Ruby-side static handle; out of scope per ADR-30 WD8.
Fiddle-based bindings — separate rigor-fiddle SKILL / plugin family (sibling, not in scope here).

Phase 1 — Coverage assessment (decide if a plugin is even needed)

Check the gem against this table. If every row is "core suffices", the SKILL terminates with "declare the dependency and stop — no plugin needed." This is the most common outcome; resist the pull to author a plugin pre-emptively.

Question about the wrapped gem's source	Answer	Verdict
Does the binding file use literal `attach_function :name, [args], ret` calls (no wrapping DSL like `sodium_function`)?	yes	core suffices
	no (custom DSL)	needs plugin — `BindingRecognizer` registration (ADR-30 WD2)
Are the bindings in this gem's `lib/`, or in a sibling gem (like `ffi-rzmq-core` for `ffi-rzmq`)?	this gem	core suffices
	sibling gem	needs plugin — either ADR-25 bundled RBS or wait on ADR-10 progress
Are method names generated dynamically from an option catalog (`define_method` over `iterate option_table`)?	no	core suffices
	yes (ethon-style)	needs plugin — ADR-16 Tier B/C
Does the high-level wrapper class layer add semantics richer than what the FFI primitive return type captures (e.g. "this `:pointer` is always a 32-byte signing-key buffer")?	no — wrapper is a thin pass-through	core suffices
	yes — wrapper carries domain invariants the FFI types don't	plugin recommended for RBS refinement (the wrapper still types correctly without the plugin, just less precisely)
Does the gem use `typedef :pointer, :handle_name` aliases for opaque pointers?	yes — names follow `_ptr` / `_handle` / `Ptr` / `Handle`	core suffices (heuristic per ADR-30 WD4)
	yes — a name matches the pattern but should stay a plain `:pointer`	core suffices; add the alias to the `rigor-ffi` plugin's `exceptions:` config in `.rigor.yml`

Read the full file on GitHub · 334 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

11d ago First seen · 334 lines · 59 tokens per session scan A fdabff733eea

Subscribe to this mod's changes

rigor-ffi-plugin-author is a skill published in the GitHub repository rigortype/rigor (107 stars, last pushed today), licensed MPL-2.0. It adds 59 tokens to every session and 4,004 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-26.

Building agents Languages Ruby

rigor-ffi-plugin-author next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
rigor-ffi-plugin-authorrigortype/rigor	Skill	107	today	MPL-2.0	A	59	Claude Code
newclacky-ai/openclacky	Skill	1.2k	yesterday	MIT	A	10	Claude Code
rspec-conventionsrootstrap/rails_api_base	Skill	634	2d ago	MIT	A	82	Claude Code
dhh-rails-styledavekilleen/Dex	Skill	512	8d ago	MIT	A	115	Claude Code
ruby-patternssoftspark/ai-toolkit	Skill	179	10d ago	Apache-2.0	A	60	Claude Code
ruby-idiomsirahardianto/awesome-agv	Skill	158	23d ago	MIT	A	61	Claude Code, Codex
ruby-rulessoftspark/ai-toolkit	Skill	179	10d ago	Apache-2.0	A	48	Claude Code

rigor: Skill for Claude Code