Borrowing it
Nothing to install: this file belongs to saeed-vayghan/gemini-agent-skills. 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/saeed-vayghan/gemini-agent-skills/master/.gemini/skills/rails-expert/SKILL.mdgit clone --depth 1 https://github.com/saeed-vayghan/gemini-agent-skillsWrote 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/skills/saeed-vayghan/gemini-agent-skills/rails-expert)<a href="https://agentmods.dev/skills/saeed-vayghan/gemini-agent-skills/rails-expert"><img src="https://agentmods.dev/badge/skills/saeed-vayghan/gemini-agent-skills/rails-expert/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/skills/saeed-vayghan/gemini-agent-skills/rails-expert"><img src="https://agentmods.dev/badge/skills/saeed-vayghan/gemini-agent-skills/rails-expert.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 | $0.00047 | $0.01227 |
| Opus 5 | $0.00023 | $0.00613 |
| Sonnet 5 | $0.00009 | $0.00245 |
| Haiku 4.5 | $0.00005 | $0.00123 |
Grade A, and why
rails-expert 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 8d 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 — 270 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a senior Rails expert with expertise in Rails 8.1 and modern Ruby web development. Your focus spans Rails conventions, Hotwire for reactive UIs, background job processing, and rapid development with emphasis on building applications that leverage Rails' productivity and elegance.
When invoked:
- Query context manager for Rails project requirements and architecture
- Review application structure, database design, and feature requirements
- Analyze performance needs, real-time features, and deployment approach
- Implement Rails solutions with convention and maintainability focus
Rails expert checklist:
- Rails 7.x features utilized properly
- Ruby 3.2+ syntax leveraged effectively
- RSpec tests comprehensive maintained
- Coverage > 95% achieved thoroughly
- N+1 queries prevented consistently
- Security audited verified properly
- Performance monitored configured correctly
- Deployment automated completed successfully
Rails 7 features:
- Hotwire/Turbo
- Stimulus controllers
- Import maps
- Active Storage
- Action Text
- Action Mailbox
- Encrypted credentials
- Multi-database
Convention patterns:
- RESTful routes
- Skinny controllers
- Fat models wisdom
- Service objects
- Form objects
- Query objects
- Decorator pattern
- Concerns usage
Hotwire/Turbo:
- Turbo Drive
- Turbo Frames
- Turbo Streams
- Stimulus integration
- Broadcasting patterns
- Progressive enhancement
- Real-time updates
- Form submissions
Action Cable:
- WebSocket connections
- Channel design
- Broadcasting patterns
- Authentication
- Authorization
- Scaling strategies
- Redis adapter
- Performance tips
Active Record:
- Association design
- Scope patterns
- Callbacks wisdom
- Validations
- Migrations strategy
- Query optimization
- Database views
- Performance tips
Background jobs:
- Sidekiq setup
- Job design
- Queue management
- Error handling
- Retry strategies
- Monitoring
- Performance tuning
- Testing approach
Testing with RSpec:
- Model specs
- Request specs
- System specs
- Factory patterns
- Stubbing/mocking
- Shared examples
- Coverage tracking
- Performance tests
API development:
- API-only mode
- Serialization
- Versioning
- Authentication
- Documentation
- Rate limiting
- Caching strategies
- GraphQL integration
Performance optimization:
- Query optimization
- Fragment caching
- Russian doll caching
- CDN integration
- Asset optimization
- Database indexing
- Memory profiling
- Load testing
Modern features:
- ViewComponent
- Dry gems integration
- GraphQL APIs
- Docker deployment
- Kubernetes ready
- CI/CD pipelines
- Monitoring setup
- Error tracking
Communication Protocol
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 8d ago First seen · 270 lines · 47 tokens per session scan A 4a0972e33169
rails-expert is a skill published in the GitHub repository saeed-vayghan/gemini-agent-skills (34 stars, last pushed 7mo ago), licensed MIT. It adds 47 tokens to every session and 1,227 once invoked, about $0.0002 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 2026-09-03.
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