`.cursorrules` Confessional: How I Got My AI to Write Its Own Damn Rules (And You Can Too)

· origo's blog


Ever feel like you're stuck in a loop, telling your AI coding assistant "No, PascalCase for React components!" for the umpteenth time? AI sidekicks are phenomenal, but let's be honest, they're not psychic. They need project-specific guardrails, or you'll spend half your day refactoring their enthusiastic-but-misguided brain-farts. My own early days with AI involved a lovingly crafted RULES.md – a pipe dream, really – aimed at staunching the flow of AI-generated chaos.

Turns out, the brilliant minds at Cursor were way ahead of me, formalizing this very idea into .cursorrules. These are typically Markdown-based files (often with an .mdc extension, living in a .cursorrules directory) that act as your project's bespoke playbook for its AI. Think of them as the onboarding docs your AI desperately needs but never got. It might know generic coding patterns, but it sure as heck doesn't know your project's specific style, architectural quirks, or that library you swore you'd never use again (but totally do).

These rules bridge that gap, leading to:

And you don't even need to start from a blank slate. The Awesome CursorRules repository is a treasure trove of pre-built rules for a slew of languages and frameworks (Python, Next.js, Gitflow, Clean Code – the gang's all here). Grab what fits.

But here’s where it gets really juicy, the part that took this from "neat feature" to "game-changer" for me: instead of just manually curating these rules, you can train your AI to help build and refine its own rulebook. This transforms .cursorrules from a static config file into a dynamic, evolving brain for your AI partner. Yeah, you read that right.

The Core Loop: Make Your AI Learn from Its Blunders (and Document Them) #

So, .cursorrules are cool. But the real magic? Teaching your AI to co-author its own improvement manual. Your AI becomes that keen-but-green junior dev, the one who occasionally submits a PR that works but tramples three project conventions and resurrects a deprecated library. You wouldn't just silently fix it, would you? Nah, you'd walk them through the why and point them to the team docs. Same rodeo here, except your AI can help update those docs itself.

Here's the battle plan I've settled into, and it’s been a productivity multiplier:

1. Lay the Groundwork (Don't Expect Miracles from Scratch) #

You can't expect the AI to conjure its own comprehensive rulebook out of thin air. Snag a generic clean-code.mdc from that Awesome CursorRules repo I mentioned. Add one for your primary language or framework. This gives your AI a decent starting point, a sandbox rather than a barren wasteland.

2. The "Whoopsie, Let's Carve That in Stone" Feedback Loop #

This is where the real learning happens.

Pro Tip: Specificity is Your Superpower. Don't just grumble "That's wrong." Guide!

1Hey AI, good effort on that Node.js service, but you used a synchronous file read.
2We're strictly async/await for I/O here to keep the event loop purring, not weeping.
3Could you add a rule to `node-express.mdc` emphasizing async I/O for file operations
4in service layers? Maybe toss in a 'good' example snippet?

Or for a style fumble:

1Nearly there, but you used `var`. We banished `var` to the JavaScript history books.
2Please update `javascript-style.mdc` to enforce `let`/`const` for all variable
3declarations. Thne, show me the new rules.

Or even more directly after it botches an API interaction:

1You missed the crucial error handling for that external API call. Bad AI.
2Update `api-interactions.mdc` to ensure we *always* include robust error checks
3and logging for external calls. Propose a rule, please."

3. Review the AI's Homework (You're Still the Lead) #

The AI will attempt to update its .cursorrules. It might add a bullet point, rephrase a sentence, or suggest a new section. Your job is quality control.

4. Commit the Wisdom (Code and Rules) #

Happy with the AI's proposed rule? Merge it. Treat your .cursorrules files like any other critical project artifact: version control them with Git. As I banged on about in my 12-Factor Agents piece, "Own Your Prompts"—and by extension, own your rules. When you commit a code fix stemming from an AI misstep, commit the .cursorrules update that aims to prevent it from happening again. Traceability, folks. It's not just for bugs.

5. Test Drive the New Smarts #

Next time you're working with your AI, see if it remembers its lesson. Does it adhere to the new rule? You can even playfully try to lead it into the same trap to verify its learning.

Why This Self-Correction Loop Is Gold:

Sure, you'll still want to use globs for targeting rules, be hyper-specific in your instructions (these silicon savants are very literal), and even positively reinforce when the AI does something exceptionally well. And yes, periodic spring-cleaning of the ruleset is wise.

But this AI-driven self-correction? It makes the whole system sing. Your AI co-pilot isn't just flying; it's helping update the flight manual after every patch of turbulence, with you as the captain ensuring the updates make sense.

Level Up: Meta-Rules for AI Rule-Crafting (Yes, Really) #

Prepare for a little mind-bending. If you really want to push this AI partnership (and who doesn't enjoy some elegant meta-recursion?), establish rules for how the AI proposes changes to .cursorrules. Rules for writing rules. It's delightfully meta and surprisingly effective.

You're not just teaching your AI what coding rules to follow; you're training it on how to be a responsible co-author of its own instruction manual. This is next-level AI whispering. You could have a meta-rules.mdc or a dedicated section in your main rules:

 1# Meta-Rules: How We Update Our .cursorrules
 2
 3## Proposing Rule Changes
 4- When suggesting a new rule or modifying an existing one, you *must*:
 5    1. Clearly state the **problem** this rule solves (e.g., "AI sometimes uses
 6       the deprecated FooBar pattern for widget construction").
 7    2. Propose **concise, unambiguous** rule text. No fluff.
 8    3. If it's about code patterns, include a **minimal 'good' example** (and a
 9       'bad' one if it clarifies). Show, don't just tell.
10    4. Briefly explain **the 'why'**: Why is this rule beneficial for *this
11       specific project*?
12
13## Justifying Rule Edits
14- If I (the human) ask you to update rules and explain your reasoning, provide
15  a clear, brief summary: what changed, why it changed, and how it addresses the
16  issue.

Then, when your AI messes up and you tell it to update the rules (e.g., "You used a magic number there. Bad form. Update style-guide.mdc to forbid magic numbers..."), you can add: "...and ensure your proposal follows our 'Meta-Rules for Updating .cursorrules'."

Boom. Now its suggestions for rule changes will be structured, justified, and easier for you to review. You're teaching it to contribute effectively to the project's codified wisdom.

Beyond Typos and Tabs: Embedding Real Architectural Wisdom #

Getting your AI to remember camelCase versus snake_case is table stakes. The real power of .cursorrules shines when you start embedding genuine architectural principles and hard-won best practices. This is where your AI partner transitions from a glorified linter to something resembling a seasoned (albeit digital) team member.

As you and your AI log more project hours, you'll graduate from "don't do that dumb thing" rules to "here's how we build smart things around here":

Codify this level of wisdom, and you're not just getting syntactically correct code. You're getting code that reflects your project's philosophy and aligns with patterns your team trusts. You're scaling your best practices through your AI.

The Future is Forged in Collaboration (Especially with a Well-Trained AI) #

Tools like .cursorrules aren't just another feature; they signal a fundamental shift in human-AI collaboration in the development trenches. We're moving beyond simply tossing prompts over the fence and hoping for gold. We're becoming active trainers, mentors, and guides, shaping our AI collaborators to grasp the nuanced realities of our projects. It's the difference between giving your co-pilot a generic flight manual for "an airplane" versus the detailed schematics and emergency procedures for the specific, quirky, battle-scarred aircraft you're actually flying.

My initial RULES.md was a cry for help to reduce daily papercuts. .cursorrules gives that cry structure, power, and shareability. As AI continues its march into every corner of our development lives, these project-specific indoctrination systems will become foundational for effective human-AI teaming.

Your Move: Time to Properly Onboard Your AI #

If you're wrestling with an AI coding assistant, especially in the Cursor ecosystem, do yourself a favor: dive into .cursorrules. Grab a starter set from the "Awesome" repo, start customizing, and then, crucially, start teaching your AI to help maintain them. The clarity gain is like switching from a fuzzy CRT monitor to a Retina display.

And hey, if you craft a brilliant set of rules for an obscure framework or a bleeding-edge stack, share it! Contribute back to the collective knowledge. That’s how we all level up in this rapidly evolving landscape.

The era of treating your AI like a clueless intern you constantly have to micromanage is drawing to a close. By teaching your AI to refine its own .cursorrules based on its mistakes and your expert guidance, you're fostering an adaptive learning system. Your AI partner becomes an increasingly valuable, context-aware member of your team—one that genuinely gets smarter with every interaction.

This is more than just clever prompting. It's about building a robust feedback loop, turning "D'oh!" moments into durable, codified wisdom.

What are your war stories from the AI frontier? Have you taught your AI new tricks by making it update its own guidelines? What other techniques are you pioneers using to forge truly intelligent AI partnerships? The field is wide open. Let's explore it.

Now, go make your AI less of a wildcard and more of a wingman. Happy (and much smarter) coding!

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