typescript-magician

Designs complex generic types, refactors `any` types to strict alternatives, creates type guards and utility types, and resolves TypeScript compiler errors. Use when the user asks about TypeScript (TS) types, generics, type inference, type guards, removing `any` types, strict typing, type errors, `infer`, `extends`, conditional types, mapped types, template literal types, branded/opaque types, or utility types like `Partial`, `Record`, `ReturnType`, and `Awaited`.

6 stars

byHarmeet10000

View on GitHub Installation ↓

Best use case

typescript-magician is best used when you need a repeatable AI agent workflow instead of a one-off prompt.

Teams using typescript-magician should expect a more consistent output, faster repeated execution, less prompt rewriting.

When to use this skill

You want a reusable workflow that can be run more than once with consistent structure.

When not to use this skill

You only need a quick one-off answer and do not need a reusable workflow.
You cannot install or maintain the underlying files, dependencies, or repository context.

Installation

Claude Code / Cursor / Codex

$curl -o ~/.claude/skills/typescript-magician/SKILL.md --create-dirs "https://raw.githubusercontent.com/Harmeet10000/skills/main/skills/backend/Node_Bun/typescript-magician/SKILL.md"

Manual Installation

Download SKILL.md from GitHub
Place it in .claude/skills/typescript-magician/SKILL.md inside your project
Restart your AI agent — it will auto-discover the skill

How typescript-magician Compares

Feature / Agent	typescript-magician	Standard Approach
Platform Support	Not specified	Limited / Varies
Context Awareness	High	Baseline
Installation Complexity	Unknown	N/A

Frequently Asked Questions

What does this skill do?

Where can I find the source code?

You can find the source code on GitHub using the link provided at the top of the page.

Related Guides

AI Agents for Coding

Browse AI agent skills for coding, debugging, testing, refactoring, code review, and developer workflows across Claude, Cursor, and Codex.

SKILL.md Source

## When to use

Use this skill for:
- TypeScript errors and type challenges
- Eliminating `any` types from codebases
- Complex generics and type inference issues
- When strict typing is needed

## Instructions

When invoked:
1. Run `tsc --noEmit` to capture the full error output before making changes
2. Identify the root cause of type issues (unsound inference, missing constraints, implicit `any`, etc.)
3. Craft precise, type-safe solutions using advanced TypeScript features
4. Eliminate all `any` types with proper typing — validate each replacement still satisfies call sites
5. Confirm the fix compiles cleanly with a second `tsc --noEmit` pass

Capabilities include:
- Advanced generics and conditional types
- Template literal types and mapped types
- Utility types and type manipulation
- Brand types and nominal typing
- Complex inference patterns
- Variance and distribution rules
- Module augmentation and declaration merging

For every TypeScript challenge:
- Explain the type theory behind the problem
- Provide multiple solution approaches when applicable
- Show before/after type representations
- Include comprehensive type tests
- Ensure full IntelliSense support

## Quick Examples

### Eliminating `any` with generics

**Before**
```ts
function getProperty(obj: any, key: string): any {
  return obj[key];
}
```

**After**
```ts
function getProperty<T, K extends keyof T>(obj: T, key: K): T[K] {
  return obj[key];
}
// getProperty({ name: "Alice" }, "name") → inferred as string ✓
```

### Narrowing an unknown API response

**Before**
```ts
async function fetchUser(): Promise<any> {
  const res = await fetch("/api/user");
  return res.json();
}
```

**After**
```ts
interface User { id: number; name: string }

function isUser(value: unknown): value is User {
  return (
    typeof value === "object" &&
    value !== null &&
    "id" in value &&
    "name" in value
  );
}

async function fetchUser(): Promise<User> {
  const res = await fetch("/api/user");
  const data: unknown = await res.json();
  if (!isUser(data)) throw new Error("Invalid user shape");
  return data;
}
```

## Reference

Read individual rule files for detailed explanations and code examples:

### Core Patterns
- [rules/as-const-typeof.md](rules/as-const-typeof.md) - Deriving types from runtime values using `as const` and `typeof`
- [rules/array-index-access.md](rules/array-index-access.md) - Accessing array element types using `[number]` indexing
- [rules/utility-types.md](rules/utility-types.md) - Built-in utility types: Parameters, ReturnType, Awaited, Omit, Partial, Record

### Advanced Generics
- [rules/generics-basics.md](rules/generics-basics.md) - Fundamentals of generic types, constraints, and inference
- [rules/builder-pattern.md](rules/builder-pattern.md) - Type-safe builder pattern with chainable methods
- [rules/deep-inference.md](rules/deep-inference.md) - Achieving deep type inference with F.Narrow and const type parameters

### Type-Level Programming
- [rules/conditional-types.md](rules/conditional-types.md) - Conditional types for type-level if/else logic
- [rules/infer-keyword.md](rules/infer-keyword.md) - Using `infer` to extract types within conditional types
- [rules/template-literal-types.md](rules/template-literal-types.md) - String manipulation at the type level
- [rules/mapped-types.md](rules/mapped-types.md) - Creating new types by transforming existing type properties

### Type Safety Patterns
- [rules/opaque-types.md](rules/opaque-types.md) - Brand types and opaque types for type-safe identifiers
- [rules/type-narrowing.md](rules/type-narrowing.md) - Narrowing types through control flow analysis
- [rules/function-overloads.md](rules/function-overloads.md) - Using function overloads for complex function signatures

### Debugging
- [rules/error-diagnosis.md](rules/error-diagnosis.md) - Strategies for diagnosing and understanding TypeScript type errors

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