TypeScript Strictness Review skill for Claude and Codex

TypeScript Strictness Review as an AI skill. It asks for The code, Current tsconfig, Runtime and 2 more, then does the rest. Free to install in Claude or Codex.

Install it once and Claude or Codex runs it for you. When your request matches, your AI loads the skill, asks for anything it is missing, and works through the template itself. Prefer to fill it in by hand? See the full prompt template.

Download the skill (.zip) · View SKILL.md

When it is used

Use when a TypeScript codebase has loose compiler settings, scattered any types, or unsafe async code and needs a path to strict mode. Do not use for converting a JavaScript project to TypeScript from scratch. Related topics: coding, technical.

What it will ask you for

• The code (longer free text)
• Current tsconfig (longer free text)
• Runtime (choose one: Node, Browser, Both, Edge)
• Areas (choose any: Strict flags, Removing any, Narrowing, Discriminated unions, Async safety, Null handling, Type exports)
• Migration style (choose one: All at once, File by file, Only new code)

How it works

1. Compare the tsconfig with the strict family and list which flags to enable, ordered by how few errors each is likely to add.
2. Find every any, non-null assertion, and unchecked cast, and replace each with a proper type or a narrowing check.
3. Rewrite state-like data as a discriminated union with an exhaustive switch that ends in a never check.
4. Scan async code for unawaited promises, async callbacks in forEach, and catch blocks that hide errors, and fix each.
5. Lay out a staged plan for turning on strictness at the chosen migration style.

What you get

Findings in fix order with before and after snippets, followed by a staged rollout plan for the compiler flags.

What it watches out for

• Enabling every strict flag in one commit, which floods the team with hundreds of errors and stalls the effort.
• Swapping any for unknown without adding the narrowing check, so the code only moves the problem.
• Using non-null assertions to silence the compiler, which trades a compile error for a runtime crash.

How to install

Claude.ai and the Claude desktop app

1. Download the skill .zip.
2. Open Settings, then Capabilities, and find Skills.
3. Choose Upload skill and select the .zip.
4. Ask Claude for help with the task. It loads the skill when your request matches.

Claude Code

1. Download the skill .zip.
2. Unzip it into ~/.claude/skills/ (or .claude/skills/ inside a project).
3. Start a new session. Claude Code loads the skill when your request matches.

Codex

1. Download the skill .zip.
2. Unzip it into ~/.agents/skills/ (or .agents/skills/ inside a project).
3. Codex picks it up on its own. Type $ and the skill name to use it, or just ask for the task.

Cursor

1. Download the Cursor rule (.mdc).
2. Save it in .cursor/rules/ inside your project.
3. Cursor's agent applies the rule when your request matches its description.

AGENTS.md (Codex, Cursor, and other coding agents)

1. Copy the AGENTS.md section.
2. Paste it into AGENTS.md at the root of your repository, creating the file if needed.
3. Coding agents that read AGENTS.md follow it when your request fits.