Borrowing it
Nothing to install: this file belongs to levifig/rails-instructions. 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/levifig/rails-instructions/main/.github/copilot-instructions.mdgit clone --depth 1 https://github.com/levifig/rails-instructionsWrote 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/instructions/levifig/rails-instructions/copilot-instructions)<a href="https://agentmods.dev/instructions/levifig/rails-instructions/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/levifig/rails-instructions/copilot-instructions/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/instructions/levifig/rails-instructions/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/levifig/rails-instructions/copilot-instructions.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 | $0.00630 | $0.00630 |
| Opus 5.5 | $0.00252 | $0.00252 |
| Sonnet 5.5 | $0.00126 | $0.00126 |
| Haiku 4.5 | $0.00063 | $0.00063 |
Grade A, and why
rails-instructions copilot-instructions.md 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.
How it starts
The opening of the file, as written. The whole thing — 146 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Copilot Assistant Rules
Assistant Behavior
- Be terse and direct in responses
- Ask clarifying questions before implementing complex features
- Anticipate needs and suggest improvements proactively
- Focus on high-quality, production-ready code
- Use analogies when explaining complex concepts
Code Generation Principles
Quality Standards
- Generate code that could ship to production
- Follow established patterns in the codebase
- Maintain consistency with existing architecture
- Every piece of code should be testable
- Documentation is not optional
Style Guidelines
- Respect .prettierrc and linting configurations
- Prefer clarity over cleverness
- Use descriptive names that reveal intent
- Keep line lengths reasonable
- Consistent indentation and formatting
Architecture Focus
- Think in systems, not just functions
- Consider scalability implications
- Design for maintainability
- Separate concerns appropriately
- Make dependencies explicit
Project Awareness
Context Loading
Always check for .github/PROJECT_CONTEXT.md which contains:
- Current architectural patterns
- Technology stack decisions
- Team conventions and preferences
- Recent design decisions
- Performance considerations
- Known technical debt
File Organization
- Follow existing project structure
- Keep related code together
- Use standard naming conventions
- Maintain clear module boundaries
Code Patterns
Error Handling
- Fail fast with clear messages
- Use appropriate error types
- Handle errors at the right level
- Provide actionable error messages
- Log errors appropriately
Testing Approach
- Write tests alongside implementation
- Test edge cases explicitly
- Use descriptive test names
- Keep tests simple and focused
- Mock external dependencies
Documentation
- Document why, not what
- Include examples for complex APIs
- Keep docs in sync with code
- Use consistent documentation format
- Document assumptions and constraints
Language-Specific Rules
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 · 146 lines · 630 tokens per session scan A 8bf49420486e
rails-instructions copilot-instructions.md is an instructions file published in the GitHub repository levifig/rails-instructions (56 stars, last pushed 1y ago), licensed MIT. It adds 630 tokens to every session, about $0.0025 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.
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