@types/react@^18 in dependencies breaks type-checking in React 19 projects #2594

Summary

Since 3.33.0, braintrust lists @types/react: ^18.3.1 under dependencies. As far as I can tell it is only needed for the braintrust/custom-views type definitions (dist/custom-views.d.ts imports ReactNode from react), which came in with #2191.

Because it is a hard dependency, every consumer gets React 18 types installed, including projects that don't use custom views or don't use React at all. In a React 19 project, this can break tsc.

What happened

We use pnpm (workspace) and React 19 (@types/react@19). After upgrading braintrust from 3.32.0 to 3.35.0, pnpm hoisted @types/react@18.3.31 into node_modules/.pnpm/node_modules. Packages that import types from react without declaring @types/react themselves (in our case @sentry/react) then resolved React 18 types, while our own code used React 19 types. tsc --noEmit failed with errors like this:

error TS2322: Type 'React.ReactNode' is not assignable to type 'import(".../@types+react@18.3.31/node_modules/@types/react/index").ReactNode'.
  Type 'ReactElement<unknown, string | JSXElementConstructor<any>>' is not assignable to type 'ReactNode'.
    Property 'children' is missing in type 'ReactElement<unknown, string | JSXElementConstructor<any>>' but required in type 'ReactPortal'.

We work around it with a pnpm override ("braintrust>@types/react": "^19"), or by staying on 3.32.0.

Versions

• braintrust: 3.33.0 – 3.37.1 (not in 3.32.0)
• @types/react in the project: 19.2.x
• Package manager: pnpm 11 (workspace)

Suggestion

Declare @types/react (and react, if needed) as an optional peer dependency, for example:

"peerDependencies": {
  "@types/react": ">=18"
},
"peerDependenciesMeta": {
  "@types/react": { "optional": true }
}

That way, projects that use custom views get the @types/react they already have, whatever its version, and other projects don't get React types installed at all.