/rails-audit-thoughtbot

name: rails-audit-thoughtbot
description: Perform comprehensive code audits of Ruby on Rails applications based on thoughtbot best practices. Use this skill when the user requests a code audit, code review, quality assessment, or analysis of a Rails application. The skill analyzes the entire codebase focusing on testing practices (RSpec), security vulnerabilities, code design (skinny controllers, domain models, PORO with ActiveModel), Rails conventions, database optimization, and Ruby best practices. Outputs a detailed markdown audit report grouped by category (Testing, Security, Models, Controllers, Code Design, Views) with severity levels (Critical, High, Medium, Low) within each category.

Rails Audit Skill (thoughtbot Best Practices)

Perform comprehensive Ruby on Rails application audits based on thoughtbot's Ruby Science and Testing Rails best practices, with emphasis on Plain Old Ruby Objects (POROs) over Service Objects.

Audit Scope

The audit can be run in two modes: 1. **Full Application Audit**: Analyze entire Rails application 2. **Targeted Audit**: Analyze specific files or directories

Execution Flow

Step 1: Determine Audit Scope

Ask user or infer from request:

• Full audit: Analyze all of `app/`, `spec/` or `test/`, `config/`, `db/`, `lib/`
• Targeted audit: Analyze specified paths only

Step 2: Collect Optional Metrics (SimpleCov + RubyCritic)

Ask the user **both questions upfront** in a single `AskUserQuestion` so they can decide once:

• **Question**: "Before starting the audit, would you like to collect automated metrics?\n\n1. **SimpleCov** — runs your test suite to capture actual code coverage percentages\n2. **RubyCritic** — analyzes code complexity, duplication, and smells (does not run tests)\n\nBoth are recommended for the most thorough audit."
• **Options**: "Yes to both (Recommended)" / "SimpleCov only" / "RubyCritic only" / "Skip both"

Based on the user's choice, spawn the accepted subagents **in parallel** using the Task tool. Both can run at the same time because SimpleCov modifies the test helper while RubyCritic only reads source files — they don't conflict.

**SimpleCov subagent** (if accepted):

> Read the file `agents/simplecov_agent.md` and follow all steps described in it. The audit scope is: {{SCOPE from Step 1}}. Return the coverage data in the output format specified in that file.

**RubyCritic subagent** (if accepted):

> Read the file `agents/rubycritic_agent.md` and follow all steps described in it. The audit scope is: {{SCOPE from Step 1}}. Return the code quality data in the output format specified in that file.

**After both agents finish**, clean up:

• If SimpleCov ran: `rm -rf coverage/`
• If RubyCritic ran: `rm -rf tmp/rubycritic/`

**Interpreting responses:**

• `COVERAGE_FAILED` / `RUBYCRITIC_FAILED`: no data for that tool — use estimation mode (SimpleCov) or omit the section (RubyCritic). Note the failure reason in the report.
• `COVERAGE_DATA`: parse and keep in context for Steps 4 and 5 (overall coverage, per-directory breakdowns, lowest-coverage files, zero-coverage files).
• `RUBYCRITIC_DATA`: parse and keep in context for Steps 4 and 5 (overall score, per-directory ratings, worst-rated files, top smells, most complex files).

Step 3: Load Reference Materials

Before analyzing, read the relevant reference files:

• `references/code_smells.md` - Code smell patterns to identify
• `references/testing_guidelines.md` - Testing best practices
• `references/poro_patterns.md` - PORO and ActiveModel patterns
• `references/security_checklist.md` - Security vulnerability patterns
• `references/rails_antipatterns.md` - Rails-specific antipatterns (external services, migrations, performance)

Step 4: Analyze Code by Category

All analysis must stay within the project root and the bundle path. To inspect gem source, use `bundle show <gem>` to locate it (see "Locate gem source" under Analysis Commands) — never run filesystem-wide searches like `find /`. If you delegate any category below to subagents, include this constraint in each subagent's prompt.

Analyze in this order:

1. **Testing Coverage & Quality**

• If SimpleCov data was collected in Step 2, use actual coverage percentages instead of estimates
• Cross-reference per-file SimpleCov data: files with 0% coverage = "missing tests"
• Check for missing test files
• Identify untested public methods
• Review test structure (Four Phase Test)
• Check for testing antipatterns

2. **Security Vulnerabilities**

• SQL injection risks
• Mass assignment vulnerabilities
• XSS vulnerabilities
• Authentication/authorization issues
• Sensitive data exposure

3. **Models & Database**

• Fat model detection
• Missing validations
• N+1 query risks
• Callback complexity
• Law of Demeter violations (voyeuristic models)
• If RubyCritic data was collected, flag models with D/F ratings or high complexity

4. **Controllers**

• Fat controller detection
• Business logic in controllers
• Missing strong parameters
• Response handling
• Monolithic controllers (non-RESTful actions, > 7 actions)
• Bloated sessions (storing objects instead of IDs)
• If RubyCritic data was collected, flag controllers with D/F ratings or high complexity

5. **Code Design & Architecture**

• Service Objects → recommend PORO refactoring
• Large classes
• Long methods
• Feature envy
• Law of Demeter violations
• Single Responsibility violations
• If RubyCritic data was collected, cross-reference D/F rated files and high-complexity files with manual code review findings

6. **Views & Presenters**

• Logic in views (PHPitis)
• Missing partials for DRY
• Helper complexity
• Query logic in views

7. **External Services & Error Handling**

• Fire and forget (missing exception handling for HTTP calls)
• Sluggish services (missing timeouts, synchronous calls that should be backgrounded)
• Bare rescue statements