Rails With AI

Rails-with-AI

A `CLAUDE.md` template that teaches [Claude Code](https://docs.anthropic.com/en/docs/claude-code) modern Rails 8+ best practices. Drop it into any Rails project and Claude will follow production-grade conventions for Ruby style, ActiveRecord, Hotwire, security, testing, and more — automatically, on every interaction.

Why

Claude Code reads `CLAUDE.md` from your working directory and applies its rules to every conversation (including sub-agents). Without guardrails, AI-generated Rails code can drift: symbol-form callbacks, `after_create` for jobs instead of `after_create_commit`, fat controllers with business logic, Devise in new projects, unscoped queries that leak data, and more. This template codifies the conventions experienced Rails teams (and DHH) enforce in code review, so Claude follows them from the first line.

Two Versions

Pick the one that fits your project.

File	Size	Contains	Best for
`CLAUDE.md.FULL`	40,146 chars	All rules plus BAD/GOOD code examples	Projects where you want Claude to pattern-match from examples, or onboarding human devs alongside Claude
`CLAUDE.md.SHORT`	28,917 chars	All rules, no code examples	Context-sensitive projects, large monorepos, or when you already trust Claude to apply Rails idioms correctly

Both files cover the **same rules** — the only difference is whether each rule is illustrated with a BAD/GOOD code block. Rules that lived inside code-only examples in the FULL version were folded into prose in SHORT, so no guidance is lost.

What's inside (click to expand)

Area	Key rules
Output & Efficiency	Token-efficient responses (adapted from claude-token-efficient), no sycophantic fluff, ASCII-safe output
Ruby Style & Code Quality	Expanded conditionals over guard clauses (DHH), m