🧠 Cursor Rule — Auto-Setup TypeScript Configs

Summary

Automate TypeScript configuration so projects begin with strict typing, correct module resolution, and predictable builds. A well-structured tsconfig improves runtime safety, prevents common bugs, and keeps the codebase consistent.

Objectives

• Enforce strict type checking to catch issues early
• Align Node, bundlers, and test environments with proper resolution modes
• Produce reliable build outputs such as declarations and maps
• Simplify onboarding with clear, documented settings

Principles

1. Strictness is a runtime safety feature, not a preference.

2. Configs should be modular and extendable.

3. Module resolution must match the actual runtime.

4. Comments and documentation help maintain long-term clarity.

Implementation Pattern

Step 1: Create a base config with essential strictness flags such as strict, noImplicitAny, strictNullChecks, exactOptionalPropertyTypes, and noUncheckedIndexedAccess.

Step 2: Layer environment-specific configs.

Frontend configs include DOM types.

Backend configs rely on Node typings.

Build configs include declaration output and source maps.

Step 3: Choose the correct module resolution mode.

Use bundler for modern tooling such as Vite and Next.js.

Use node16 for Node-based projects using ESM.

Step 4: Validate with Cursor by running type checks and verifying that no unsafe any values or missing null checks appear.

Bug Prevention Examples

• Prevents undefined access errors that would otherwise cause runtime crashes.
• Ensures imports resolve predictably across development, CI, and production.
• Ensures declaration maps exist for debugging stack traces in deployed environments.

Anti-Pattern (Before)

A loose config where strict is disabled and skipLibCheck hides underlying type issues. This leads to inconsistent behavior across environments and hidden bugs.

Recommended Pattern (After)

A layered configuration using tsconfig.base.json as the foundation, extended by app, server, and build configs with clear intent and strict validation.

Best Practices

• Document settings inside the config.
• Use incremental builds for monorepos.
• Avoid combining frontend and backend typings.
• Keep skipLibCheck off unless intentionally justified.

Cursor Prompts

"Generate a complete tsconfig setup with base, app, and build configs, including comments."

"Typecheck the entire project and surface any unsafe or inconsistent patterns."

"Explain how different module resolution modes affect this codebase."

Notes

Treat TypeScript configuration as part of your reliability strategy, not a one-time setup step.