Karpathy Guidelines

---
name: karpathy-guidelines
description: Behavioral guidelines to reduce common LLM coding mistakes. Use when writing, reviewing, or refactoring code.
license: MIT
source: https://github.com/forrestchang/andrej-karpathy-skills
---

# Karpathy Guidelines

Behavioral guidelines to reduce common LLM coding mistakes, derived from [Andrej Karpathy's observations](https://x.com/karpathy/status/2015883857489522876) on LLM coding pitfalls. Adapted from [forrestchang/andrej-karpathy-skills](https://github.com/forrestchang/andrej-karpathy-skills) (MIT).

**Tradeoff:** These guidelines bias toward caution over speed. For trivial tasks, use judgment.

## 1. Think Before Coding

**Don't assume. Don't hide confusion. Surface tradeoffs.**

Before implementing:
- State your assumptions explicitly. If uncertain, ask.
- If multiple interpretations exist, present them - don't pick silently.
- If a simpler approach exists, say so. Push back when warranted.
- If something is unclear, stop. Name what's confusing. Ask.

## 2. Simplicity First

**Minimum code that solves the problem. Nothing speculative.**

- No features beyond what was asked.
- No abstractions for single-use code.
- No "flexibility" or "configurability" that wasn't requested.
- No error handling for impossible scenarios.
- If you write 200 lines and it could be 50, rewrite it.

Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.

## 3. Surgical Changes

**Touch only what you must. Clean up only your own mess.**

When editing existing code:
- Don't "improve" adjacent code, comments, or formatting.
- Don't refactor things that aren't broken.
- Match existing style, even if you'd do it differently.
- If you notice unrelated dead code, mention it - don't delete it.

When your changes create orphans:
- Remove imports/variables/functions that YOUR changes made unused.
- Don't remove pre-existing dead code unless asked.

The test: Every changed line should trace directly to the user's request.

## 4. Goal-Driven Execution

**Define success criteria. Loop until verified.**

Transform tasks into verifiable goals:
- "Add validation" → "Write tests for invalid inputs, then make them pass"
- "Fix the bug" → "Write a test that reproduces it, then make it pass"
- "Refactor X" → "Ensure tests pass before and after"

For multi-step tasks, state a brief plan:

```
1. [Step] → verify: [check]
2. [Step] → verify: [check]
3. [Step] → verify: [check]
```

Strong success criteria let you loop independently. Weak criteria ("make it work") require constant clarification.

---

**These guidelines are working if:** fewer unnecessary changes in diffs, fewer rewrites due to overcomplication, and clarifying questions come before implementation rather than after mistakes.

---

## Toolkit working preferences (developer agents)

> Moved here from every variant's `CLAUDE.md` in v2.0-pr4. All 12 coder agents preload this skill (`skills: [karpathy-guidelines]`), so these arrive at spawn without costing an always-loaded byte. The hook-enforcement line stayed in `CLAUDE.md` because it is PO-relevant.

> **Actor note:** implementation-level preferences below (tests, CI fixes, minimal fix, post-merge verification, commit style) are PERFORMED by developer agents — the PO enforces them by putting them in spawn prompts and rejecting deliverables that violate them. The PO itself never edits code or runs builds/tests.

These are the judgement calls no hook can make:

- **Implement, don't suggest** — deliver working changes via spawned agents; infer intent from context instead of asking for a fuller spec
- **Minimal fix first** — ask "what is the smallest change that fixes this?" and cut scope aggressively. Over-engineered first attempts cause regressions and force a clawback later
- **Analyze before coding** — enumerate edge cases and identify every caller before implementing. For a bug fix, verify the root cause from data (query the DB, read the logs) before writing code
- **Re-plan on failure** — if an approach is not working after a reasonable attempt, stop and rethink the approach rather than pushing through
- **Tests** — write general solutions, never hard-code the expected values. If a test looks wrong, say so
- **Post-merge verification** — after any merge or conflict resolution, run the full build and suite, and check for dropped imports or silently reverted lines
- **Update docs with code** — a change to behaviour, an API, config, or setup updates its docs in the same commit
- **Commit messages explain why** — a reviewer reading the diff cold should not have to ask
- **Clean finish** — committed, merged, worktree removed, branch deleted, temp scripts gone. Anything left behind gets reported, with the reason
- **Checkpoint long sessions** — commit and push intermediate work; output truncation has cost 9+ hours of context before now
- **Learn from corrections** — capture the pattern to Open Brain immediately so the same mistake does not repeat