`useMatches` missing generic

[y-nk]

Reproduction

Try to write a hook to generate breadcrumbs using useMatches such as:

import { UIMatch, useMatches } from 'react-router'

type BreadcrumbMatch = UIMatch<unknown, { breadcrumb: string }>

export function useBreadcrumbs(): { title: string; path?: string }[] {
  return useMatches()
    .filter((m): m is BreadcrumbMatch => !!m.handle?.breadcrumb)
    .map((match, i, a) => ({
      path: i < a.length - 1 ? match.pathname : undefined,
      title: match.handle.breadcrumb,
    }))
}

There will be a typescript error because handle is defaulted to unknown, which forces us to write:

type MaybeBreadcrumbMatch = UIMatch<unknown, { breadcrumb?: string }>

export function useBreadcrumbs(): { title: string; path?: string }[] {
  return (useMatches() as MaybeBreadcrumbMatch[])
    .filter((m): m is BreadcrumbMatch => !!m.handle?.breadcrumb)

System Info

Binaries:
    Node: 24.2.0
    pnpm: 10.13.1

(The rest is irrelevant to my issue.)

Used Package Manager

npm

Expected Behavior

There should be a way to pass the generics of returned UIMatch from the useMatches() hook. Maybe a useMatches<A = unknown, B = unknown>(): UIMatch<A, B>[] would be non breaking and appropriate.

Actual Behavior

There's no way to type correctly without making use of as because the default type of handle is unknown