[Bug] Claude suggests deprecated React.FormEvent instead of React.SubmitEvent for React 19+ projects

Summary

When working in a React 19+ project, Claude Code consistently suggests or reverts form submit event handler types to the deprecated React.FormEvent<HTMLFormElement>, even after the user has manually corrected them to the current React.SubmitEvent<HTMLFormElement>.

Steps to Reproduce

1. Open a React 19+ TypeScript project
2. Write or ask Claude to write a form onSubmit handler
3. Claude suggests: (e: React.FormEvent<HTMLFormElement>) => { ... }
4. Manually correct it to: (e: React.SubmitEvent<HTMLFormElement>) => { ... }
5. On the next edit or review pass, Claude reverts or re-suggests the deprecated type

Expected Behavior

Claude should use React.SubmitEvent<HTMLFormElement> for form submit handlers when the project is on React 19+, where React.FormEvent is deprecated.

Actual Behavior

Claude uses React.FormEvent<HTMLFormElement> regardless of the React version, forcing users to repeatedly fix the same deprecation.

Context

• React.FormEvent / React.FormEventHandler were deprecated in React v19.2.10
• The correct replacement is React.SubmitEvent<HTMLFormElement>
• Reference: https://github.com/remix-run/react-router/issues/14795

Environment

• React version: 19+
• TypeScript project

Suggested Fix

Claude should detect the React version from package.json and use the appropriate event types. For React >= 19, prefer React.SubmitEvent over React.FormEvent for form submit handlers.

🤖 Reported via Claude Code