Karpathy Guardrails

Four rules. Load them into context at the start of every task. The reviewer enforces them as a Pass-1 filter before it looks at code quality.

1. Think Before Coding

Before the first edit, write down:

What am I actually building? One sentence. If you cannot state it, stop.
What am I assuming? List every assumption. If any is load-bearing and unverified, flag NEEDS_CONTEXT and ask — do not guess.
What does success look like? Map each acceptance criterion to a concrete test, check, or observable behaviour. If a criterion is not verifiable, propose a sharpening via the revision skill (automated-trace subsection), not a vague attempt.

Refusing to produce code is allowed. A task with unknown scope is a spec bug, not a coding task.

2. Simplicity First

The correct amount of code is the minimum that meets the acceptance criteria.

No speculative features. No abstraction layer "in case we need it."
No new dependencies unless the task requires one and no existing dep fits.
No "while I'm in here" refactors. Surface them as separate kits.
Duplication is not always wrong. Three similar lines usually beat a premature abstraction with two configuration knobs.

If the diff is larger than the acceptance criteria seem to demand, explain why in the commit body. If you cannot, trim the diff.

3. Surgical Changes

Every line in the diff must trace back to an acceptance criterion. Touching code outside the task's owned files is justified only when a requirement forces it. Examples of violations:

Fixing a formatter warning in an unrelated file.
Renaming a helper "to match new convention."
Reordering imports, docstrings, whitespace.
Tightening a type signature the task did not ask about.

If you see a real bug in adjacent code, log it to .cavekit/history/backprop-log.md as a candidate kit item and keep it out of this task's diff.

4. Goal-Driven Execution

Transform vague tasks into verifiable success criteria before execution.

A task that cannot be verified is not a task — escalate it.
The verification plan must be concrete: exact commands, exact assertions, exact files to inspect. "Make sure it works" is not a plan.
After implementation, run the verification plan. Report the output.

Role-specific enforcement

task-builder — must produce, alongside code, a Verification Report listing each AC, the verification step, and the observed result.
reviewer — must refuse to advance to Pass 2 (code quality) if Pass 1 finds any of: undeclared assumptions, diff lines unjustified by an AC, out-of-scope edits, or unreachable verification steps.
planner — must reject kits that contain un-testable ACs. They are spec bugs and block planning.
inspector — must flag completed tasks whose verification logs are missing or hand-waved.

When you are tempted to break a rule

You are probably over-confident about a shortcut that will cost more than the delay of asking. Stop and note the tension in the commit body or in the build log so the reviewer can judge.