React 19 migration traps your AI keeps falling...

Every AI coding assistant was trained on React 18 patterns. When you're building with React 19 + Next.js 15, the AI generates code that compiles perfectly but fails at runtime or behaves unexpectedly. Here are the 4 most common React 19 traps I've documented, with .mdc rules to prevent each one. 1. useFormStatus() returns { pending: false } forever The trap: The AI places useFormStatus() in the same component that renders the <form>. This will NEVER work — useFormStatus only reads status from a