Code Style: Exist, Reuse, Mirror, Symmetry

What it does

Gives Claude seven ordered rules for writing code inside an existing project — earlier rules win when they conflict:

• Prove the code needs to exist: drop one-implementation abstractions, single-caller config points, unreachable branches, and speculative scaffolding. New tests must name the regression they protect, and should extend an existing test when it covers the same contract.
• Reuse code: check whether an existing method can be reused or generalized before adding a helper.
• Reuse patterns: find the closest analogous feature and replicate its decomposition, control flow, and guard clauses.
• Mirror surrounding code: match brace style, comment style, naming, blank-line spacing, and code density by reading nearby files first.
• Maintain symmetry: when adding fooB() next to fooA(), align names, parameter order, route paths, config keys, event names, env vars, CLI flags, and file naming — renaming the older name by default unless it's a published contract.
• Logical ordering: insert methods, switch cases, and fields where the existing grouping or business lifecycle says, not at the end.
• Default to no comment: refactor until the comment is unnecessary; keep only load-bearing constraints.

Trust-boundary validation, data-loss-preventing error handling, security controls, accessibility, and explicit requests override the minimalism rule.

Who it's for

• Developers shipping changes into legacy or team-owned codebases who want stylistic consistency.
• Teams tired of AI-generated over-abstraction, redundant comments, and low-value tests.
• Tech leads who want a language-agnostic, written review standard.

Examples

1. New endpoint: model a GET /orders/:id handler on the existing GET /users/:id one, matching route naming, error handling, and file placement.
2. Symmetric sibling: add exportToJson() beside exportToCsv() with identical parameter order and config key naming, renaming the old key if the pair becomes asymmetric.
3. Refactor request: ask "clean up this module" and Claude traces callers, removes dead branches and single-implementation interfaces, and replaces comments with better extraction.

Read the instructions in this file and follow them to help me:
https://raw.githubusercontent.com/tobihagemann/turbo/HEAD/claude/skills/code-style/SKILL.md

What I want: (describe your task here)

Install the skill I found on AI Skill Mart.
Copy the claude/skills/code-style folder from the GitHub repo tobihagemann/turbo into my ~/.claude/skills/code-style/.
When it's done, tell me in one line what this skill can do.