Claude misidentifies React StrictMode's intentional behavior as a bug and attempts impossible solutions

Problem

React StrictMode intentionally calls effects twice in development mode, but Claude Code misidentifies this as a bug and repeatedly attempts impossible solutions.

Reproduction Steps

1. React + Next.js project (StrictMode enabled)
2. Component with useEffect calling an API
3. User request: "API is called twice in dev mode, make it call only once"
4. Claude attempts various solutions (isFetchingRef, lastFetchedDepsRef, etc.) but all fail
5. Code breaks - data no longer displays on screen
6. Eventually reverted with git restore

Expected Behavior

Claude should understand React's behavior and respond:

• "Calling effects twice in dev mode is React StrictMode's intentional behavior"
• "In production, it only runs once"
• "To call once in dev mode, you can:"

1. Set reactStrictMode: false
2. Use caching libraries like React Query or SWR

• Provide clear explanation and alternatives from the start

Actual Behavior

• Assumes the problem is solvable and keeps trying
• Wrong approach: trying to block with component-level refs (StrictMode fully unmounts/remounts components, resetting refs)
• Adds logic like lastFetchedDepsRef, which causes data not to load
• Wastes time and tokens, eventually reverts everything

Environment

• React 18+ with StrictMode
• Next.js 15
• useEffect + API calls

Suggestions

1. Learn React's official StrictMode documentation
2. Recognize "double execution in dev mode" as normal, unsolvable behavior
3. For impossible problems: clearly state "This is not solvable" + provide alternatives
4. Don't waste time on wrong solutions