EngineeringJune 16, 2026
React 19 Migration
How we migrated Agentbot from React 18 to React 19 in one session.
Why React 19?
React 19 brings performance improvements, better TypeScript support, and is required for json-render integration. The migration was straightforward — only 6 TypeScript errors to fix.
What Changed
useRef()now requires an argumentRefObject<T>includes| null- Some third-party APIs changed signatures
- ESLint 9 needs flat config format
The Result
Migration completed in one session. Zero deprecated APIs in codebase. All tests pass. Performance improved.