TypeScript Development (5.x)

Critical Output Rules

• State strict TypeScript choices explicitly: strict, noUncheckedIndexedAccess, exactOptionalPropertyTypes, no any by default, and unknown for untrusted input.
• Validate untrusted API/JSON responses at the boundary before returning typed data.
• Favor composition and small functions/hooks over large classes, global state, or mixed concerns.
• Handle async errors explicitly with Result/discriminated unions or typed thrown errors at boundaries.
• Always mention behavior tests for success and failure paths. For React, include component or user-behavior tests for loading, success, error, and validation states.
• Include verification commands when code changes: bunx tsc --noEmit, bun test, and lint/format commands when configured.
• Keep dependencies minimal; add schema/form libraries only when real complexity beats a small type guard or helper.
• Do not run destructive shell commands. For broad or risky changes, state the risk and ask before acting.

Core Philosophy

Strict-mode-always, interface-vs-type, discriminated unions, flat control flow, the Result-type error pattern, the no-destructive-commands safety rule, and the post-generation verification loop are in references/principles.md — read it before generating code.

Quick Patterns