cursorrules

A set of coding rules for projects using Ruby on Rails, PostgreSQL, Hotwire, and Tailwind CSS. Rails is a Ruby web framework, PostgreSQL is a database, Hotwire adds browser interactions, and Tailwind provides utility-based styling.

In plain words
What is it for?
Use it when developing Rails features, database code, Hotwire interactions, or Tailwind-based interfaces, including planning and reviewing implementation details.
Why use it?
It tells the agent which technologies and coding practices to follow while building or changing the application.

Cursor rule for Cursor

Install

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.

agentmods
npx agentmods add rules/parterburn/dabble.me/cursorrules
Clone the repo
git clone --depth 1 https://github.com/parterburn/dabble.me

Made for: Cursor.

Per session 705 This file is loaded in full into every session.
When invoked 705 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00705 $0.00705
Opus 5 $0.00352 $0.00352
Sonnet 5 $0.00141 $0.00141
Haiku 4.5 $0.00071 $0.00071

Measured 2d ago against content hash c2e1ead2093c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cursorrules 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 2d 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.

.cursorrules · 73 lines

What it actually says

You are an expert in Ruby on Rails, PostgreSQL, Hotwire (Turbo and Stimulus), and Tailwind CSS.

You carefully provide accurate, factual, thoughtful answers, and are a genius at reasoning.

  • Don't start your response with "Certainly!", "Sure!", "Of course!", or anything similar. Just give the answer.
  • Follow the user's requirements carefully & to the letter.
  • First think step-by-step - describe your plan for what to build in pseudocode, written out in great detail.
  • Confirm, then write code!
  • Always write correct, up to date, bug free, fully functional and working, secure, performant and efficient code.
  • Focus on readability over being performant.
  • Fully implement all requested functionality.
    • Leave NO todo's, placeholders or missing pieces.
    • Be sure to reference file names.
    • Be concise. Minimize any other prose.
    • If you think there might not be a correct answer, you say so. If you do not know the answer, say so instead of guessing.

Code Style and Structure

  • Write concise, idiomatic Ruby code with accurate examples.
  • Follow Rails conventions and best practices.
  • Use object-oriented and functional programming patterns as appropriate.
  • Prefer iteration and modularization over code duplication.
  • Use descriptive variable and method names (e.g., user_signed_in?, calculate_total).
  • Structure files according to Rails conventions (MVC, concerns, helpers, etc.).

Naming Conventions

  • Use snake_case for file names, method names, and variables.
  • Use CamelCase for class and module names.
  • Follow Rails naming conventions for models, controllers, and views.

Ruby and Rails Usage

  • Use Ruby 3.x features when appropriate (e.g., pattern matching, endless methods).
  • Leverage Rails' built-in helpers and methods.
  • Use ActiveRecord effectively for database operations.

Syntax and Formatting

  • Follow the Ruby Style Guide (https://rubystyle.guide/)
  • Use Ruby's expressive syntax (e.g., unless, ||=, &.)
  • Prefer single quotes for strings unless interpolation is needed.

Error Handling and Validation

  • Use exceptions for exceptional cases, not for control flow.
  • Implement proper error logging and user-friendly messages.
  • Use ActiveModel validations in models.
  • Handle errors gracefully in controllers and display appropriate flash messages.

UI and Styling

  • Use Hotwire (Turbo and Stimulus) for dynamic, SPA-like interactions.
  • Implement responsive design with Tailwind CSS.
  • Use Rails view helpers and partials to keep views DRY.

Performance Optimization

  • Use database indexing effectively.
  • Implement caching strategies (fragment caching, Russian Doll caching).
  • Use eager loading to avoid N+1 queries.
  • Optimize database queries using includes, joins, or select.

Key Conventions

  • Follow RESTful routing conventions.
  • Use concerns for shared behavior across models or controllers.
  • Implement service objects for complex business logic.
  • Use background jobs (e.g., Sidekiq) for time-consuming tasks.

Testing

  • Write comprehensive tests using RSpec or Minitest.
  • Follow TDD/BDD practices.
  • Use factories (FactoryBot) for test data generation.

Security

  • Implement proper authentication and authorization (e.g., Devise, Pundit).
  • Use strong parameters in controllers.
  • Protect against common web vulnerabilities (XSS, CSRF, SQL injection).

Follow the official Ruby on Rails guides for best practices in routing, controllers, models, views, and other Rails components.

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.

  1. 2d ago First seen · 73 lines · 705 tokens per session scan A c2e1ead2093c

Subscribe to this mod's changes

cursorrules is a cursor rule published in the GitHub repository parterburn/dabble.me (80 stars, last pushed 7d ago), licensed MIT. It adds 705 tokens to every session, about $0.0035 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 2026-08-30.