Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add ericrisco/rsc-harness --skill railsgit clone --depth 1 https://github.com/ericrisco/rsc-harnessWrote 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.
[](https://agentmods.dev/skills/ericrisco/rsc-harness/rails)<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/rails"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/rails/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.
<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/rails"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/rails.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Excessive Agency · line 145 Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
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 | $0.00093 | $0.02992 |
| Opus 5 | $0.00046 | $0.01496 |
| Sonnet 5 | $0.00019 | $0.00598 |
| Haiku 4.5 | $0.00009 | $0.00299 |
Grade A, and why
rails 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 7d 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.
How it starts
The opening of the file, as written. The whole thing — 265 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Build Rails the omakase way
Write Rails the way a core-adjacent senior would: fat-enough models, skinny controllers, zero N+1, strong parameters, migrations that are reversible and safe on a live table, and tests that exercise the request rather than the implementation. Lean into the Rails 8 "omakase" defaults instead of fighting them — the framework already made the boring choices for you.
This is Rails the framework: the MVC request cycle, ActiveRecord, Hotwire, Active
Job, the Rails test stack. The moment code stops loading Rails — a plain script, a gem,
an Enumerable refactor with no ActiveRecord in sight — it is no longer this skill.
That is ruby (see ../ruby/SKILL.md).
Target versions
Rails 8.1 (stable line, released 2025-10-22; 8.0 shipped 2024-11-07)
Ruby 3.4+ (floor for current Rails)
Jobs/queue Solid Queue (default Active Job backend — database-backed, no Redis)
Cache Solid Cache (default cache store — database-backed)
WebSockets Solid Cable (default Action Cable adapter — database-backed)
Assets Propshaft (default; Sprockets is legacy)
JS Importmaps (default; no Node build step required)
Deploy Kamal 2 + Thruster
Front-end Hotwire = Turbo 8 + Stimulus
Auth `rails generate authentication` (built in; no Devise for basic auth)
A fresh Rails 8 app needs no Redis and no Node. Stop reaching for Sidekiq/Redis or
a JS bundler by reflex — the Solid trifecta and Importmaps already cover the default
case. Rails 8.1 adds Active Job Continuations (resumable long jobs), Structured Event
Reporting, local CI via config/ci.rb, and Markdown rendering.
When to use
- Generating/editing anything under
app/(models, controllers, views, jobs, mailers, channels),config/routes.rb, ordb/migrate/. - ActiveRecord work: associations, scopes, validations, callbacks,
includes/preload/eager_load, query objects, migrations. - Hotwire UI: Turbo Frames/Streams, morphing, Stimulus controllers, broadcasts.
- Background work via Active Job / Solid Queue; fragment caching via Solid Cache.
- Rails testing: Minitest model/integration/system tests, fixtures, RSpec + Capybara, debugging flaky Turbo system tests.
- Upgrading a Rails app or migrating off Redis/Sidekiq onto the Solid stack.
What ships with it
6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 7d ago First seen · 265 lines · 93 tokens per session scan A 7b26bd2a6112
rails is a skill published in the GitHub repository ericrisco/rsc-harness (81 stars, last pushed today), licensed MIT. It adds 93 tokens to every session and 2,992 once invoked, about $0.0005 per session on Opus 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 2026-09-03.
Other skills, from other repositories
rails-docs
Ruby on Rails 8.1 — Active Record, Action View/Controller, routing, Active Support, testing, security, caching.
rails-hotwire
Hotwire (Turbo Drive, Turbo Frames, Turbo Streams, Stimulus).
building-mcp-servers
Authors an MCP server with the official SDK and gates.
hunt-auth-bypass
Hunting skill for auth bypass vulnerabilities. Built from 4 public bug bounty reports. Use when hunting auth bypass on any target.
hunt-idor
Hunting skill for idor vulnerabilities. Built from 26 public bug bounty reports. Use when hunting idor on any target.
hunt-xxe
Hunting skill for xxe vulnerabilities. Built from 4 public bug bounty reports. Use when hunting xxe on any target.