typescript-advanced-types

Overview of typescript-advanced-types skill

The typescript-advanced-types skill is a focused guide for generating and reviewing advanced TypeScript type logic, especially when plain interfaces and basic generics stop being enough. It is best for frontend developers, library authors, and AI-assisted coding workflows that need help with conditional types, mapped types, template literal types, utility types, and reusable generic patterns.

What this skill is actually for

Use typescript-advanced-types when your real job is not “write some TypeScript,” but “design type behavior that stays safe as code scales.” Typical cases include:

• building reusable component or hook APIs
• typing form schemas and validation flows
• shaping API client responses
• deriving types from config objects
• enforcing relationships between input and output types
• migrating loosely typed JavaScript patterns into stricter TypeScript

Best-fit users

This typescript-advanced-types skill is a strong fit if you already know everyday TypeScript and need help with harder type modeling decisions. It is especially useful for:

• frontend teams working in React, Next.js, or component libraries
• developers authoring shared utility types
• engineers reviewing type-heavy pull requests
• AI users who want better prompts than “make this generic”

If you are still learning basic interfaces, unions, narrowing, and function typing, this skill may feel too advanced as a starting point.

What makes it different from a generic prompt

A normal prompt often produces type tricks without explaining tradeoffs. The typescript-advanced-types skill is more useful when you need structured guidance across the main advanced patterns, not just a one-off snippet. It pushes the work toward durable type design: when to use generics, how to constrain them, when conditional types help, and where complexity can become a maintenance cost.

Adoption decision in one minute

Install typescript-advanced-types if you want a reusable TypeScript thinking framework for type-safe frontend development and library design. Skip it if your need is mostly runtime logic, framework setup, or beginner TypeScript syntax. The value is highest when the hard part of the task is type modeling itself.

How to Use typescript-advanced-types skill

typescript-advanced-types install context

The repository does not expose a separate package install flow inside SKILL.md, so users typically add the skill from the parent skills repo:

npx skills add https://github.com/wshobson/agents --skill typescript-advanced-types

After adding it, invoke it inside your AI coding environment when the task involves advanced type construction, refactoring, or review.

Read this file first

Start with:

• plugins/javascript-typescript/skills/typescript-advanced-types/SKILL.md

This skill is self-contained. There are no extra resources/, rules/, or helper scripts, so most of the usable guidance is in that one file. That is good for quick adoption, but it also means output quality depends heavily on the quality of your prompt and examples.

What input the skill needs

The typescript-advanced-types usage pattern works best when you provide concrete code, not abstract intent alone. Give the skill:

• the current type or API shape
• the desired developer experience
• sample valid and invalid calls
• whether inference or explicit generic arguments should be preferred
• framework context such as React props, API responses, or form state

Weak input:

• “Make this type safer.”

Strong input:

• “Create a generic type for a form field config object where type: "select" requires options, type: "text" forbids options, and the resulting value type is inferred from the field definition.”

Turn a rough goal into a strong prompt

A good typescript-advanced-types guide prompt usually includes four parts:

1. current code
2. target behavior
3. edge cases
4. readability constraints

Example:

I have this API client response type:

type ApiResponse<T> =
  | { ok: true; data: T }
  | { ok: false; error: string };

I want helper types that:
- extract success payloads
- extract error payloads
- work across unions
- stay readable for a frontend team
- avoid overly clever type-level programming

Show the final types, explain why they work, and note any maintainability tradeoffs.

That prompt is better than asking for “advanced utility types” because it gives the skill a concrete contract to optimize around.

Common tasks where this skill helps most

Use typescript-advanced-types for Frontend Development when working on:

• discriminated prop unions for components
• polymorphic component props
• route or event name generation with template literal types
• typed selectors and derived state
• API response transformation helpers
• generic hooks with inferred return types
• schema-driven UI configuration
• utility types that remove duplication across feature modules

Suggested workflow for real projects

A practical workflow is:

1. paste the real code causing friction
2. ask for the simplest type design that satisfies the constraints
3. request 2 to 3 alternatives if inference is brittle
4. test the result in your editor or CI with valid and invalid examples
5. ask for simplification if the final type is hard to explain to teammates

This matters because many advanced TypeScript solutions are technically correct but hard to maintain. The best output is usually not the most clever one.

How to ask for the right abstraction level

Be explicit about whether you need:

• a one-off local type
• a reusable utility type
• a public library-facing API type
• a migration-safe intermediate type

For example, if this is internal feature code, ask the skill to optimize for readability over maximum reuse. If it is a shared package, ask for stable naming, constraints, and examples that communicate intent.

What the skill covers well

From the source, the skill clearly emphasizes:

• generics
• generic constraints
• conditional types
• mapped types
• template literal types
• utility-type style composition

That makes it most valuable when you need patterns and examples across the advanced type toolbox, not just a single isolated answer.

What can block good results

The biggest blocker is underspecified desired behavior. Advanced types are about relationships, so the skill needs examples of those relationships. Without them, it may generate something elegant but wrong in practice.

Other common blockers:

• missing sample inputs and outputs
• unclear runtime invariants
• asking for “maximum type safety” without maintainability limits
• not saying whether distribution over unions is wanted
• not clarifying if any, unknown, or fallback types are acceptable

Quick quality checks before you ship

Before accepting the output from typescript-advanced-types, verify:

• inferred types match actual editor behavior
• invalid examples fail as expected
• error messages remain understandable
• teammates can read the utility without deep type-system expertise
• runtime code still matches the type-level assumptions

If the type solution needs a paragraph to explain basic usage, it may be too complex for the codebase.

typescript-advanced-types skill FAQ

Is typescript-advanced-types good for beginners?

Usually not as a first TypeScript resource. The skill assumes you already understand interfaces, unions, intersections, narrowing, and basic generics. Beginners can still use it, but mainly for guided examples rather than production-heavy type design.

When is this better than an ordinary AI prompt?

It is better when the task spans multiple advanced type concepts and you want a reliable pattern-selection guide. A plain prompt may return a working trick; typescript-advanced-types is more useful when you need a cleaner path through generics, constraints, conditional logic, and mapped transformations.

Is it useful for frontend teams specifically?

Yes. typescript-advanced-types for Frontend Development is a strong match because many frontend APIs depend on inferred props, discriminated states, config-driven rendering, and typed async data flows. The skill is especially relevant for React component libraries, forms, and API-driven UI layers.

Does it include runnable tooling or automation?

No. This is documentation-first guidance inside SKILL.md, not a toolchain with scripts or reference files. Its usefulness comes from how well it shapes prompts and design decisions, not from automation.

When should I not use typescript-advanced-types?

Do not reach for it when:

• the problem is mostly runtime validation
• basic interfaces solve the issue
• your team cannot maintain dense type-level code
• the bug is caused by framework behavior, not type modeling
• you need schema libraries, codegen, or linting more than type design advice

Can it help with library API design?

Yes. This is one of the best use cases. If you are designing reusable hooks, helpers, or components where consumer ergonomics matter, the skill can help balance inference, constraints, and API clarity.

How to Improve typescript-advanced-types skill

Give the skill examples, not just goals

The fastest way to improve typescript-advanced-types output quality is to provide:

• one valid usage example
• one invalid usage example
• the expected inferred type
• any error behavior you want to preserve

Advanced types become much easier to design when the desired call-site experience is visible.

State your tradeoffs up front

Tell the skill whether to prioritize:

• readability
• strongest possible inference
• minimal generic parameters
• public API stability
• migration friendliness

Without this, it may choose a clever pattern that is correct but hard to maintain.

Ask for explanation plus final code

A strong prompt for the typescript-advanced-types skill is:

“Give me the final type, then explain which parts are generic constraints, which parts are conditional logic, and where inference could fail.”

This helps you review the output instead of copying it blindly.

Watch for common failure modes

Common issues with advanced type output include:

• over-distributed conditional types
• inference collapsing to never
• accidental widening to string or any
• unreadable nested helper types
• public APIs that require explicit generics too often

If you see these, ask the skill to simplify or to produce a more ergonomic alternative.

Iterate from simple to complex

Do not start by asking for the most generalized utility possible. Ask first for a local version that works for one case, then expand it. This often produces a clearer result than requesting a universal abstraction on the first pass.

Ask for maintainable naming

If the output introduces multiple helper types, ask the skill to rename them by intent, not mechanism. For example, names like ExtractFormValue<T> or ComponentVariantProps<T> are usually more maintainable than opaque names based on internal type tricks.

Validate with editor behavior

The best improvement loop is outside the markdown: paste the result into your editor and inspect hover types, autocomplete behavior, and error messages. Then return with specific failures:

• “Inference fails on arrays”
• “The union no longer narrows”
• “Consumers must pass generics manually”

That gives typescript-advanced-types enough signal to refine the design accurately.

Use it as a review tool, not only a generator

One high-value use of typescript-advanced-types is reviewing an existing complicated type and asking:

• what it is doing
• where it is fragile
• how to reduce nesting
• whether a runtime helper would be clearer than more type logic

That review mode is often more valuable than generating a fresh advanced type from scratch.