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.
git clone --depth 1 https://github.com/nedcodes-ok/cursorrules-collectionWrote 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/rules/nedcodes-ok/cursorrules-collection/ruby)<a href="https://agentmods.dev/rules/nedcodes-ok/cursorrules-collection/ruby"><img src="https://agentmods.dev/badge/rules/nedcodes-ok/cursorrules-collection/ruby/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/rules/nedcodes-ok/cursorrules-collection/ruby"><img src="https://agentmods.dev/badge/rules/nedcodes-ok/cursorrules-collection/ruby.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 | $0.00267 | $0.00267 |
| Opus 5.5 | $0.00107 | $0.00107 |
| Sonnet 5.5 | $0.00053 | $0.00053 |
| Haiku 4.5 | $0.00027 | $0.00027 |
Grade A, and why
ruby 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 1mo 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.
What it actually says
Ruby Cursor Rules
You are an expert Ruby developer. Follow these rules:
Code Style
- Follow Ruby Style Guide (rubocop defaults)
- 2-space indentation. snake_case methods, PascalCase classes
- Prefer single-quoted strings without interpolation
- Use trailing conditionals:
return if invalid?
Design
- Favor duck typing and composition over inheritance
- Use modules for shared behavior (mixins)
- Keep methods under 15 lines, classes under 150
- Use Struct or Data (Ruby 3.2+) for value objects
Idioms
- Use &:method_name for simple blocks:
users.map(&:name) - Use guard clauses to reduce nesting
- Use Enumerable methods over manual loops
- Use frozen_string_literal: true in all files
Error Handling
- Custom errors inherit StandardError, not Exception
- Rescue at method level, not individual lines
- Provide meaningful messages with context
Testing
- Use RSpec with descriptive context/it blocks
- Use let for lazy setup, subject for the tested thing
- Use factories (FactoryBot) over fixtures
- Use shared_examples for common interfaces
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.
- 1mo ago First seen · 39 lines · 267 tokens per session scan A cfc8f210e015
ruby is a cursor rule published in the GitHub repository nedcodes-ok/cursorrules-collection (38 stars, last pushed 7mo ago), licensed MIT. It adds 267 tokens to every session, about $0.0011 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 cursor rules, from other repositories
04-kotlin
Cursor rule "04-kotlin" from orbitalsonic/AndroidPilot, covering kotlin rules, prefer, coroutines, null safety and naming.
python
Python best practices.
typescript
TypeScript best practices.
dragonruby-best-practices-cursorrules-prompt-file
Cursor rules for DragonRuby development with best practices integration.
component-development
Modern React + TypeScript component patterns — hooks, typed props, performance optimization, forms, and testing.
ruby
Rules applied when working in Ruby files (incl. Rails).