Cursor Rules in 2026: The .cursor/rules File That Saves Your Sanity

Rules > random chats

If you're still typing we use Next.js and Drizzle every morning — you're the product.

.cursor/rules (and team variants) = persistent instructions the agent reads before it touches your repo.

Trending: cursor rules examples, cursor project rules 2026, AI coding standards.

What to put in rules

# Stack

- Next.js 15 App Router, TypeScript strict
- Drizzle ORM, Postgres on Neon
- Tailwind + shadcn/ui

# Never

- Add dependencies without asking
- Invent environment variables
- Use Pages Router patterns

# Always

- Prefer Server Actions for mutations
- Use existing `lib/` helpers
- Run types mentally before suggesting code

# Style

- Match existing file naming
- Small PRs, explain risks in bullets

Rules vs docs

Glob patterns (when supported)

Scope rules to folders:

• app/** — RSC patterns
• db/** — migration discipline
• components/ui/** — design system only

Stops the model from "fixing" marketing copy with backend patterns.

Team workflow

1. Commit rules to git
2. PR review rules like code
3. Onboard: "read rules before Agent mode"

Agencies: one rules repo template per stack (Next MVP, RN app, etc.).

Common failures

• Rules too long → model ignores tail (keep < 200 lines)
• Contradictory rules → chaotic diffs
• No "never touch" list → auth refactors from hell

TL;DR

Rules are system prompt as code. Set once, vibe forever (mostly).

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