superior-lean git:20261015.e3d1e5fA

Immutable. This exact content never changes and is served at /api/v1/blob/0e8fdf965eb5a021.

---
name: superior-lean
description: Simplify coding implementations and reviews by reusing existing capabilities and removing unjustified abstractions, dependencies, configuration, and duplication. Use when implementation complexity or over-engineering is in scope. Do not use to weaken required behavior, safety, accessibility, or compatibility.
license: MIT
---

# Superior Lean

Solve the complete requested problem with the least new surface area. Economy applies to the solution, not to understanding, correctness, or verification.

## Search for the smallest owner

Trace the affected flow and inspect callers before editing. Prefer, in order:

1. no change when the requested behavior already exists or the proposal is speculative;
2. an existing project helper, type, component, configuration point, or pattern;
3. the language standard library;
4. a native framework, browser, database, or operating-system capability;
5. an already-installed dependency;
6. a small local implementation with an explicit owner.

Stop at the first option that completely satisfies realistic behavior and fits the codebase. Fewer lines in the wrong layer are not simpler.

## Remove accidental machinery

Challenge:

- interfaces with one implementation and no stable boundary;
- factories for one fixed product;
- configuration for values that do not vary;
- wrappers that only rename an existing API;
- parallel utilities for a capability the repository already owns;
- speculative extension points, registries, flags, and migration scaffolds;
- dependencies replaceable by a few clear, maintainable local lines;
- repeated guards that should be one root-cause fix.

Prefer deletion when behavior remains intact. Do not compress straightforward code into clever expressions merely to reduce line count.

## Complexity that must remain

Do not simplify away:

- explicit user requirements or supported compatibility;
- validation and authorization at trust boundaries;
- privacy, authentication, security, and audit controls;
- recovery needed to prevent corruption or data loss;
- accessibility and responsive behavior;
- real concurrency, ordering, retry, idempotency, or cancellation guarantees;
- calibration and tuning controls required by physical or variable systems.

## Verification

Prove that removed machinery had no required consumers and that behavior remains intact. Use focused tests for non-trivial branches, parsers, state transitions, financial paths, and security-sensitive flows. For a review, distinguish observed complexity from hypothetical cleanup and recommend only changes with a concrete payoff.

Report what became simpler, what was deliberately preserved, and the real condition that would justify adding complexity later.

## Attribution

This skill is a substantially rewritten adaptation of [Ponytail](https://github.com/dietrichgebert/ponytail) by Dietrich Gebert. See [LICENSE](LICENSE).