Cursor Rules for Rails

9 Rails rules your agent actually follows: each one attaches only to the files it's about, states the version-specific behavior, and installs with one command.

$12 one-time

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Format and license: Zip, 20 KB, v1.0, 29 files. You may use and modify this kit for your own work and for clients you serve, including paid client work. Not affiliated with or endorsed by Cursor (Anysphere) or the Rails project.
Refunds: 14-day refund: if it doesn’t work and we can’t fix it, email hello@youraitools.co within 14 days and we refund you. Refund policy

What it is

9 Cursor project rules (.mdc) for Rails, scoped so each loads only when relevant, with an installer that detects your stack, an AGENTS.md exporter (Claude Code, Codex) and a rules linter. Written against current docs (checked Nov 2026; Rails 8).

What you get

The screenshot is real output from the kit’s own commands. Tested from a fresh download of this exact zip: ./run_tests.sh ran 8 tests OK on Python 3.13 and 3.10.

Real terminal output from Cursor Rules for Rails: demo and passing tests

Install in 30 seconds

python3 tools/install_rules.py --detect /path/to/app          # what it finds
python3 tools/install_rules.py /path/to/app --auto            # install rules for detected stacks into .cursor/rules/
python3 tools/install_rules.py /path/to/app --all --agents-md # everything, plus AGENTS.md
python3 tools/lint_rules.py /path/to/app/.cursor/rules --project /path/to/app

Existing files are never overwritten unless you pass --force; --dry-run previews. ./tools/demo.sh runs it on examples/sample-app; ./run_tests.sh runs the tests. As a Cursor plugin, the manifest is .cursor-plugin/plugin.json.

The rules

Rule	Loads	First instruction
rails-overview.mdc	always	Check the Rails version in Gemfile.lock before using an API
rails-models.mdc	by file (app/models//*.rb)	Back every validation that matters with a database constraint (null: false, unique index, foreign key)
rails-migrations.mdc	by file (db/migrate/*.rb)	Never edit a migration that has run outside your machine
rails-controllers.mdc	by file (app/controllers//*.rb)	Rails 8+: use params.expect(post: [:title, :body]) instead of params.require(:post).permit(:title, :body)
rails-jobs.mdc	by file (app/jobs//*.rb, config/recurring.yml, config/queue.yml)	Rails 8 production default is Solid Queue (database-backed, config/queue.yml, recurring work in...
rails-hotwire-views.mdc	by file (app/views//.erb, app/javascript//.js, app/helpers//*.rb)	Rails 8 default front end: Propshaft + importmap + Turbo + Stimulus
rails-security.mdc	by file (config//.rb, app/controllers//.rb, app/models/user.rb)	Secrets in bin/rails credentials:edit (or env vars)
rails-testing.mdc	by file (test//.rb, spec//.rb)	Use the repo's framework: Minitest (Rails default, bin/rails test) or RSpec
rails-deploy-kamal.mdc	by file (config/deploy.yml, config/deploy.*.yml, .kamal/, Dockerfile)	Rails 8 apps deploy with Kamal 2 (config/deploy.yml) and Thruster in front of Puma, from the generated Dockerfile

Honest limits

Rules guide the model; they don't enforce anything. Check version-specific advice against the versions in your lockfile (each overview rule tells the agent to do this).
Detection is file-based (package.json, manage.py/requirements, Gemfile, supabase/); in monorepos run it per package or use --stack.

Format and license

Zip, 20 KB, v1.0, 29 files. You may use and modify this kit for your own work and for clients you serve, including paid client work. Not affiliated with or endorsed by Cursor (Anysphere) or the Rails project.

FAQ

Rails 7 or 8?: Written for Rails 8 defaults; Rails 7 differences (require/permit instead of params.expect) are called out.
Will it overwrite my rules?: No, existing files are skipped unless you pass --force.
Claude Code or Codex?: Run the installer with --agents-md to write the same rules into AGENTS.md.
How do I get the files?: Right after payment, Stripe’s confirmation page shows your download link.
Refunds?: Email hello@youraitools.co within 14 days if it doesn’t work and we can’t fix it.
Can I pay with crypto?: Yes. Pay the same price in USDC or USDT on Base, Ethereum, Arbitrum, Optimism, Polygon or Solana from the "Pay with crypto" button, with no account or KYC. We check the payment on-chain and show your download links as soon as it confirms.

Get Cursor Rules for Rails

9 Cursor rules for Rails (Active Record and more), written against current docs. Installs in one command, exports AGENTS.md. $12 once.

$12 one-time

Buy and download Pay with crypto

Save with a bundle

Cursor Rules Stack Bundle: 5 products for $29 ($60 separately, you save $31).
Cursor Rules All-Stacks Bundle: 9 products for $39 ($108 separately, you save $69).

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8 Cursor rules for Supabase (Row Level Security policies and more), written against current docs. Installs in one command, exports AGENTS.md. $12 once.

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