Extract reusable logic into custom hooks (useLocalFileManager, useDragAndDrop, useDebounce, useAbortController), add ErrorBoundary for resilience, and centralize constants. Fix cursor positioning bugs, useEffect dependency issues, and add geocoding request cancellation. Improve performance with debounced localStorage writes and ref-based flags.

🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>