# Check Config Diff > This skill should be used when the user asks to "check config diff", "compare upstream config", "diff rubocop config", "sync with Rails rubocop", or wants to see differences between the upstream Rails .rubocop.yml and this repository's config/rails.yml. Use when this capability is needed. - Skill: `tomevault-io/check-config-diff` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/check-config-diff` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/check-config-diff/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/check-config-diff --- # Diff Upstream RuboCop Config Compare the upstream Rails RuboCop configuration with this repository's `config/rails.yml`. ## Instructions 1. Fetch the upstream Rails RuboCop configuration from: https://raw.githubusercontent.com/rails/rails/main/.rubocop.yml 2. Read the local configuration from: `config/rails.yml` 3. Compare both configurations and report: - Cops/settings present in upstream but missing in local - Cops/settings present in local but missing in upstream - Cops/settings with different values between upstream and local - Note any intentional local additions (marked with comments like "Additional ... by rubocop-rails_config") ## Output Format Present the differences in a clear table or list format, grouped by category (AllCops, Layout, Style, Lint, Performance, Minitest, etc.). --- > Source: [toshimaru/rubocop-rails_config](https://github.com/toshimaru/rubocop-rails_config) — distributed by [TomeVault](https://tomevault.io).