TypeScript

v1.0.0

Enforces strict TypeScript practices — proper generics, discriminated unions, exhaustive checks, and elimination of any. Weak types propagate silently through a codebase, so this skill catches the patterns that erode type safety before they spread.

14 rules

1 categories

Quality(14)

Enable TypeScript Strict Mode

Enable all strict flags in tsconfig.json (strict: true). Without strict mode, TypeScript allows null access, implicit any, and unchecked function calls that will crash at runtime.

Strict ModequalityTypeScript

CRITICAL

Automate TypeScript checks on every PR

BeforeMerge scans your pull requests against all 14 TypeScript rules automatically. Get actionable feedback before code ships.

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TypeScript Review

A review skill that ensures your TypeScript code delivers on its promise of type safety rather than just adding syntax overhead.

What it covers

Strict mode compliance — noUncheckedIndexedAccess, strictNullChecks, no implicit any
Generic patterns — proper constraints, inference-friendly signatures, avoiding over-generalization
Type narrowing — discriminated unions, exhaustive switch/case, type guards over assertions
Anti-patterns — any/unknown misuse, excessive type casting, non-null assertions as band-aids
Module boundaries — explicit return types on public APIs, branded types for domain concepts

When to use

Run this on any TypeScript project, particularly after adding new modules or when reviewers frequently catch type-related issues. Essential for shared libraries where consumers depend on accurate types.

TypeScript

Quality(14)

Enable TypeScript Strict Mode

Automate TypeScript checks on every PR

Use Discriminated Unions for State

Don't use non-null assertions (`!`) — handle null explicitly

Avoid the any Type

Use exhaustive `switch` with a `never` default

Prefer `readonly`/immutable types where possible

Use `satisfies` to validate without widening

Brand primitive IDs to prevent mix-ups

Lean on inference, annotate public API boundaries

Enable `noUncheckedIndexedAccess`

Type function returns at module boundaries

Prefer unknown Over any

Avoid Type Assertions

Prefer union string literals (or `as const`) over `enum`

TypeScript Review

What it covers

When to use