TypeScript Engineering

Use these rules when writing or editing TypeScript code. The goal is senior-level application engineering: clear ownership, precise types, explicit boundaries, small reviewable changes, and behavior that remains understandable after the original author leaves the room.

How To Use This Skill

Before changing TypeScript or TSX:

1. Read local project instructions first, including AGENTS.md, contributing docs, and nearby conventions.
2. Inspect the existing code shape before deciding on abstractions, dependencies, or file layout.
3. Make the smallest change that fully solves the request.
4. Keep runtime boundaries explicit: parse untrusted data at the edge, then pass trusted typed values inward.
5. Run the deterministic checks the project supports, such as typecheck, lint, focused tests, or format checks.

When reviewing TypeScript, lead with behavioral risks, broken contracts, weak validation, async/state bugs, missing tests, and type unsoundness. Keep style-only observations secondary unless they hide a real maintenance risk.

Core Principle

Preserve the system's important invariants before optimizing for convenience.