Borrowing it
Nothing to install: this file belongs to VSN2015/concerns_on_rails. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/VSN2015/concerns_on_rails/master/CLAUDE.mdgit clone --depth 1 https://github.com/VSN2015/concerns_on_railsWrote 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/instructions/vsn2015/concerns_on_rails/claude-md)<a href="https://agentmods.dev/instructions/vsn2015/concerns_on_rails/claude-md"><img src="https://agentmods.dev/badge/instructions/vsn2015/concerns_on_rails/claude-md/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/instructions/vsn2015/concerns_on_rails/claude-md"><img src="https://agentmods.dev/badge/instructions/vsn2015/concerns_on_rails/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.13057 | $0.13057 |
| Opus 5.5 | $0.05223 | $0.05223 |
| Sonnet 5.5 | $0.02611 | $0.02611 |
| Haiku 4.5 | $0.01306 | $0.01306 |
Grade A, and why
concerns_on_rails CLAUDE.md 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 6d 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 — 595 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
Commands
# Run all tests (use the asdf-pinned Ruby; see Gemfile.lock PATH pin)
ASDF_RUBY_VERSION=3.2.2 bundle exec rspec
# Run a single spec file
ASDF_RUBY_VERSION=3.2.2 bundle exec rspec spec/concerns/models/publishable_spec.rb
# Run a single example by line number
ASDF_RUBY_VERSION=3.2.2 bundle exec rspec spec/concerns/models/publishable_spec.rb:28
# Run against one Rails line from the CI matrix (6.0, 6.1, 7.0, 7.1, 7.2, 8.0, 8.1)
ASDF_RUBY_VERSION=3.2.2 BUNDLE_GEMFILE=gemfiles/rails_6.0.gemfile bundle exec rspec
# Build the gem
gem build concerns_on_rails.gemspec
# Install locally (version comes from lib/concerns_on_rails/version.rb)
gem install ./concerns_on_rails-<VERSION>.gem
Architecture
This is a Ruby gem providing a collection of ActiveSupport::Concern modules that Rails
models and controllers include directly. There is no Rails app — tests use an
in-memory SQLite database configured in spec/support/database.rb, with a
TestModel < ActiveRecord::Base (abstract) base for spec model classes, and a
dependency-free FakeController harness (spec/support/controller_test_harness.rb) for
the controller concerns.
Model concerns live in lib/concerns_on_rails/models/<name>.rb, controller concerns in
lib/concerns_on_rails/controllers/<name>.rb, and shared internal helpers in
lib/concerns_on_rails/support/<name>.rb. lib/concerns_on_rails.rb is the loader —
fully autoload-based since the post-1.22 DX wave (each concern file requires the support
helpers it uses, plus concerns_on_rails/core — MissingDependency and the gem-level
singletons deprecator/config/setup/encryption/filter_parameter_registry — when it
touches one, so direct requires still work; spec/concerns/direct_require_spec.rb requires
every model/controller file alone in a subprocess). friendly_id/acts_as_list load lazily
with Sluggable/Sortable (absent gem → ConcernsOnRails::MissingDependency, a LoadError
subclass). Top-level aliases for the pre-1.6 module paths (e.g. ConcernsOnRails::Sluggable)
resolve lazily via const_missing in lib/concerns_on_rails/legacy_aliases.rb. Gem-wide
config lives behind ConcernsOnRails.setup (lib/concerns_on_rails/configuration.rb);
its cache_store (store or Proc) is the fallback store for Throttleable/Idempotentable.
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.
- 6d ago Changed · +112 lines · +3,074 tokens per session 42f7ba533814
- 19d ago Changed · +24 lines · +597 tokens per session 8d064efdf44d
- 20d ago Changed · +6 lines · +260 tokens per session b76fa3cae08d
- 22d ago Changed · +83 lines · +1,907 tokens per session 5232ac1afe69
- 1mo ago Changed · +48 lines · +1,056 tokens per session 2b5738b35cbb
- 1mo ago Changed · +12 lines · +277 tokens per session e7b65aa265a1
- 1mo ago Changed · +26 lines · +563 tokens per session 60f82d26b2d4
- 1mo ago Changed · +6 lines · +161 tokens per session 369d00bef1a0
- 1mo ago Changed · +2 lines · +36 tokens per session 2709daeb32c3
- 1mo ago First seen · 276 lines · 5,126 tokens per session scan A de9797f3418f
concerns_on_rails CLAUDE.md is an instructions file published in the GitHub repository VSN2015/concerns_on_rails (26 stars, last pushed 7d ago), licensed MIT. It adds 13,057 tokens to every session, about $0.0522 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 2026-08-30.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
vscode model-prompts.instructions.md
Model-specific prompt authoring and registry guidelines.