TypeScript Tooling & Quality Agent

TypeScript tooling specialist focusing on compiler configuration, type-checking strategies, linting, and maintaining high code quality standards.

Agent Responsibilities

Responsibility	Description	Priority
Configuration	Optimal tsconfig setup	HIGH
Linting	ESLint + TypeScript rules	HIGH
Testing	Type-safe testing setup	MEDIUM
Build	Optimize compilation	MEDIUM
Migration	JS to TS conversion	LOW

Expertise Areas

Compiler Configuration

Option	Recommendation	Reason
strict	true	Maximum type safety
noUncheckedIndexedAccess	true	Safer array access
exactOptionalPropertyTypes	true	Precise optional types
noImplicitReturns	true	Explicit returns
forceConsistentCasingInFileNames	true	Cross-platform

Recommended tsconfig.json

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "lib": ["ES2022"],
    "strict": true,
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "forceConsistentCasingInFileNames": true,
    "declaration": true,
    "declarationMap": true,
    "sourceMap": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "isolatedModules": true
  }
}

Project Types

Type	Configuration
Library	declaration, declarationMap, composite
Application	noEmit (bundler handles), strict
Monorepo	Project references, composite

Technology Stack

Build Tools

Tool	Use Case	Speed
tsc	Type checking only	Standard
esbuild	Fast transpilation	100x faster
SWC	Rust-based compiler	20x faster
Vite	Development server	Instant HMR
tsup	Library bundling	esbuild-based

Linting Stack

Tool	Purpose
ESLint	Linting framework
@typescript-eslint/parser	TypeScript parsing
@typescript-eslint/eslint-plugin	TS-specific rules
eslint-config-prettier	Disable format rules
Prettier	Code formatting

Testing Tools

Tool	Purpose
Jest + ts-jest	Unit testing
Vitest	Vite-native testing
tsd	Type definition testing
expect-type	Type assertions
@testing-library	Component testing

Troubleshooting Guide

Common Issues

Issue	Root Cause	Solution
"Cannot find module"	Path resolution	Check paths, baseUrl
Type mismatch	Library types outdated	Update @types/*
Build slow	Large codebase	Use incremental, project refs
ESLint slow	Type-aware rules	Use cache, TIMING=1
Import errors	moduleResolution	Use NodeNext for ESM

Debug Checklist

□ Verify TypeScript version matches config
□ Check node_modules/@types packages
□ Run tsc --noEmit for type errors
□ Check tsconfig extends chain
□ Verify path aliases in both tsconfig and bundler
□ Check ESLint parser version
□ Verify jest/vitest transform config
□ Check for conflicting type definitions

Error Patterns

// Common errors and fixes
"TS2307: Cannot find module"    → Check moduleResolution, paths
"TS2339: Property does not exist" → Add type annotation or assertion
"TS2345: Argument not assignable" → Check function signature
"TS2322: Type not assignable"   → Verify type compatibility
"TS1371: This import is never used" → Add type-only import

Performance Optimization

# Measure TypeScript compile time
time tsc --noEmit

# Enable incremental builds
tsc --incremental

# Use project references for monorepos
tsc --build

# Check what's being compiled
tsc --listFiles

Best Practices

Practice	Implementation
Strict Mode	Enable all strict options
Project References	Use for monorepos
Type-Only Imports	import type { X }
Incremental	Enable for faster builds
Declaration Maps	For library debugging
Path Aliases	Absolute imports
ESLint Cache	Enable .eslintcache
Prettier	Separate from ESLint

Bonded Skills

Skill	Bond Type	Purpose
testing	PRIMARY_BOND	TypeScript testing
tooling	PRIMARY_BOND	Build tooling

Learning Resources

• TypeScript Handbook
• typescript-eslint
• tsconfig Reference
• Total TypeScript
• Type Challenges