claudekit/.claude/skills/languages/SKILL.md

name, description

name	description
languages	Use when working with Python, TypeScript, or JavaScript language-specific patterns — including type hints, generics, async/await, dataclasses, Pydantic, PEP 8, strict mode, tsconfig.json, Zod schemas, ESM/CJS, destructuring, optional chaining, or language idioms.

Languages

When to Use

• Python files (.py) — type hints, async/await, dataclasses, Pydantic, context managers, PEP 8
• TypeScript files (.ts, .tsx) — strict mode, generics, utility types, Zod, discriminated unions
• JavaScript files (.js, .mjs, .cjs) — ES6+ patterns, ESM/CJS, ESLint, modern syntax
• Language-specific idioms, package management (pip, pnpm), or migration between languages

When NOT to Use

• Framework-specific patterns — use backend-frameworks or frontend
• Testing — use testing
• Database queries — use databases

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Quick Reference

Language	Reference	Key features
Python	references/python.md	Type hints, dataclasses, Pydantic, asyncio, context managers, PEP 8
TypeScript	references/typescript.md	Strict mode, generics, utility types, Zod, discriminated unions, satisfies
JavaScript	references/javascript.md	ES6+, async/await, ESM/CJS, destructuring, private fields, structuredClone

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Best Practices

1. Use type hints on all public functions (Python) / enable strict mode (TypeScript).
2. Prefer dataclasses or Pydantic for structured data (Python) / interfaces for object shapes (TypeScript).
3. Use context managers for resource management (Python).
4. Never use any — use unknown instead (TypeScript).
5. Use const by default, let when needed, never var (JavaScript).
6. Validate external data at boundaries — Zod (TypeScript) or Pydantic (Python).
7. Handle all promise rejections (JavaScript/TypeScript).
8. Follow PEP 8 / ESLint + Prettier consistently.

Common Pitfalls

1. Mutable default arguments (Python) — use None with default in function body.
2. Blocking calls inside async functions (Python) — use asyncio-compatible libraries.
3. Overusing type assertions as (TypeScript) — use type guards instead.
4. Implicit type coercion (JavaScript) — always use === and !==.
5. Forgetting await (all three languages).
6. Circular imports (Python) / circular dependencies (TypeScript).
7. this binding in callbacks (JavaScript) — use arrow functions.
8. Using enums instead of const objects (TypeScript).

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Related Skills

• backend-frameworks — Framework-specific patterns
• testing — Language-specific test frameworks
• error-handling — Exception handling patterns