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/beel-collab/presets.devWrote 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/beel-collab/presets.dev/rails-rules)<a href="https://agentmods.dev/rules/beel-collab/presets.dev/rails-rules"><img src="https://agentmods.dev/badge/rules/beel-collab/presets.dev/rails-rules/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/beel-collab/presets.dev/rails-rules"><img src="https://agentmods.dev/badge/rules/beel-collab/presets.dev/rails-rules.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 | $0.00000 | $0.01023 |
| Opus 5.5 | $0.00000 | $0.00409 |
| Sonnet 5.5 | $0.00000 | $0.00205 |
| Haiku 4.5 | $0.00000 | $0.00102 |
Grade A, and why
rails-rules 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 today.
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 — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Rails Rules for Cursor: Models, Strong Params and Jobs
Install
Install the native export at .cursor/rules/rails-rules.mdc.
Copy that export, not this catalog file. Catalog fields such as tools and author are for presets.dev.
Install one skill file per name. Cursor, GitHub Copilot, Codex, Antigravity CLI, and Devin can all read .agents/skills, so a second copy with the same name collides.
Rails Rules for Cursor: Models, Strong Params and Jobs
File-scoped Cursor rule for Rails. It attaches when a matching file is in context.
Updated for Rails 8.1.4.1, Nov 2026
Do not upgrade dependencies or the framework version unless the task asks.
Rails 8.1.4.1 is the current 8.1 security release. Stay on the version in the Gemfile. 8.1's job continuations, structured events, and local CI are available when the app is already on 8.1. Read an existing model and controller before you add one.
Project shape
A controller authorizes, permits parameters, and calls a model or a service object the app already uses. Fat controllers that contain queries and mailers are not the pattern to extend. Views do not query.
Strong parameters list the keys. permit! is a bug on a public action. A nested attribute is permitted only when the user may set it.
Models and queries
Validations protect invariants. A database unique index backs a uniqueness validation. Associations that a page walks are included or preloaded. A bullet or a query-count test is how you see an N+1. An unindexed foreign key on a big table is a review.
A callback that hides a write is hard to test. Prefer an explicit method when the project does not already use that callback.
Jobs
Passing an Active Record instance to a job is normal. GlobalID stores the model name and id, and the job loads the record again when it runs. Do not tell the author to pass only ids when the app already passes records.
A retry can run the same side effect twice. A continuation resumes interrupted work. It does not make a charge or a mail idempotent. Guard those effects with a key or a state check the app already uses. Structured events follow the logger the app already configured.
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.
- today First seen · 100 lines · 0 tokens per session scan A eccf49806278
rails-rules is a cursor rule published in the GitHub repository beel-collab/presets.dev (3 stars, last pushed yesterday), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,023 tokens. 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 2026-11-13.
rails-rules compared with cursor rules from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| rails-rulesbeel-collab/presets.dev | Cursor rule | 3 | yesterday | MIT | A | 0 | Cursor |
| ponytailDietrichGebert/ponytail | Cursor rule | 190k | 15d ago | MIT | A | 604 | Cursor |
| angular-20angular/angular | Cursor rule | 101k | today | MIT | A | 0 | Cursor |
| dev-standardapache/superset | Cursor rule | 76k | today | Apache-2.0 | A | 1,147 | Cursor |
| prefer-direct-imports-over-module-mocksprisma/orm | Cursor rule | 48k | today | Apache-2.0 | A | 0 | Cursor |
| config-validation-and-normalizationprisma/orm | Cursor rule | 48k | today | Apache-2.0 | A | 0 | Cursor |
| control-plane-descriptorsprisma/orm | Cursor rule | 48k | today | Apache-2.0 | A | 0 | Cursor |