# Code Style

> Enforce mirror, reuse, and symmetry principles to keep new code consistent with surrounding code. Use when writing new code in an existing codebase, adding new features, refactoring, or making any code changes.

- Skill: `majiayu000/code-style-5` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add majiayu000/code-style-5`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/code-style-5/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/code-style-5

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# Code Style: Mirror, Reuse, Symmetry

When writing new code in an existing codebase, follow these principles:

1. **Mirror the surrounding code exactly**: Match brace style, comment style, naming conventions, blank line spacing, code density, and level of detail by reading nearby code first.
2. **Reuse existing patterns**: Find the closest analogous feature and replicate its structure (method decomposition, control flow, annotations, guard clauses). Don't introduce new patterns when an existing one fits.
3. **Reuse existing code**: Before writing a new helper, check if an existing method can be reused or generalized. If a new helper is needed, model it after its closest sibling.
4. **Maintain symmetry**: If adding `fooB()` parallel to `fooA()`, ensure naming, parameter order, and structure are symmetric. Rename `fooA()` if needed.
5. **Logical ordering**: Place new methods, switch cases, and fields in the order that mirrors the existing grouping or business lifecycle, not just appended at the end.
6. **Refactor over comment**: When code needs explanation, first try renaming, extracting helpers, or restructuring so it self-explains. A comment is an admission that refactor failed to express the rationale, acceptable only for a load-bearing constraint the code itself cannot express. When in doubt, omit it.