typescript-pro skill (jeffallan): advanced TypeScript types and tRPC

Makes your agent write strict, type-first TypeScript with advanced generics, branded types, type guards and tRPC.

Installs: 14.4K; on skills.sh
Stars: 12.2K; on GitHub
Files: 5; besides SKILL.md
Updated: Oct 2026; last repo commit

This skill gives your agent a five-step TypeScript workflow: analyze the type setup, design type-first APIs, implement with type safety, optimize the build, and test the types. It runs tsc --noEmit while implementing and again after build changes, and confirms type coverage with a tool like type-coverage.

It triggers on advanced generics, conditional or mapped types, discriminated unions, monorepo setup, and tRPC. Its must-not rules cover explicit any without justification, enums and unnecessary as assertions. Five reference files cover advanced types, type guards, utility types, configuration and patterns.

Good for

TypeScript developers designing complex types and generics
Teams tightening tsconfig and build performance
Full-stack developers wanting end-to-end type safety with tRPC

Install typescript-pro

Claude Code

Copy this prompt.

Install the typescript-pro skill in Claude Code. Run this command:

/plugin marketplace add jeffallan/claude-skills
/plugin install fullstack-dev-skills@fullstack-dev-skills

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Plugin route: adds the pack's 67 skills (the repo has 67) and its 9 workflow commands, such as /common-ground and /project:*, not only this skill. Restart Claude Code when prompted. Skills CLI route: the Quick Start says it installs skills only, without the slash commands; the --skill flag picks this one.

From the project README. Source.

What's in the skill

When it loads

Implements advanced TypeScript type systems, creates custom type guards, utility types, and branded types, and configures tRPC for end-to-end type safety. Use when building TypeScript applications requiring advanced generics, conditional or mapped types, discriminated unions, monorepo setup, or full-stack type safety with tRPC.

Sections in SKILL.md

Core Workflow
Reference Guide
Code Examples
Branded Types
Discriminated Unions & Type Guards
Custom Utility Types
Recommended tsconfig.json
Constraints
MUST DO
MUST NOT DO
Output Templates
Knowledge Reference

Key facts

Author: Jeffallan (SKILL.md: maintained by @jeffallan, Principal Consultant at Synergetic Solutions)
Repo: jeffallan/claude-skills, folder skills/typescript-pro
Installs on skills.sh: 14,411 as of 2 Nov 2026
GitHub stars: 12,161 for the whole jeffallan/claude-skills repo, 2 Nov 2026
License: MIT
Last commit in the repo: 2026-10-30
What is inside: 6 files including SKILL.md
skills.sh audits: Gen Agent Trust Hub fail, Socket pass, Snyk pass
Works in: The pack README documents a Claude Code plugin; the SKILL.md names no other client
Related skills in SKILL.md: fullstack-guardian, api-designer

What it includes

Analyze, design, implement, optimize, test types
Reviews tsconfig and type coverage, builds branded types and unions, runs tsc --noEmit to confirm zero errors, tunes project references and incremental builds, and checks type coverage.
Try: “Add branded UserId and OrderId types and make the order API type-safe end to end.”
Runs code · Core workflow
Generics, conditional, mapped and template literal types
Also recursive types, variance and type-level programming.
Read · references/advanced-types.md
Narrowing, discriminated unions, assertion functions
Also branded types and advanced narrowing.
Read · references/type-guards.md
Partial, Pick, Omit, Record and custom utilities
Also tuple and string utilities.
Read · references/utility-types.md
tsconfig strict mode, project references, module resolution
Also incremental compilation, declaration files and framework configs.
Read · references/configuration.md
Builder, factory, repository, result and state machine
Typed versions of common design patterns and a type-safe API client.
Read · references/patterns.md
Eight must-do and eight must-not rules
Strict mode, satisfies, discriminated unions and declaration files; no explicit any without justification, no enums, no unnecessary assertions.
Read · Constraints

From the official docs

Permissions

Low risk

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It edits compiler settings
The skill enables strict flags and tunes tsconfig, which can surface many new type errors. Commit first so you can compare. github.com
The plugin route installs the whole pack
The plugin manifest describes 67 skills and 9 workflow commands. The repo has no hooks file or .mcp.json at its top level; each skill is a SKILL.md with reference files. github.com

Technical details

Turning on read-only	The SKILL.md defines no read-only switch.
Scopes	Runs tsc --noEmit and a type-coverage tool Edits TypeScript files and tsconfig.json

Questions

What does the typescript-pro skill do?

It makes your agent write TypeScript in a type-first way: strict compiler flags, generics, branded types, discriminated unions, custom utility types, and tRPC for end-to-end types.

How do I install it?

Use the install box on this page. It installs this skill alone. The pack README also documents a Claude Code plugin route that installs the whole pack of skills and workflow commands.

Why does it forbid enums?

The SKILL.md says to prefer const objects with as const over enums. It lists this among its eight must-not rules and gives no further reason.

Does it need its related skills?

No. The SKILL.md lists fullstack-guardian and api-designer as related skills, but nothing in it requires them.

Is it safe to run?

It runs tsc and type-coverage and edits your TypeScript files and tsconfig. Work on a branch and review the diff.

Information

updated Nov 2, 2026

Repository: jeffallan/claude-skills
Folder: skills/typescript-pro

jeffallan/claude-skills skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 4

claude-skills README · github.com
jeffallan/claude-skills Quick Start · github.com
fullstack-dev-skills plugin manifest · github.com
typescript-pro SKILL.md · github.com