useMutationState does not update when filters change (react-query)

Describe the bug

useMutationState() ignores changes to filters. The result is only recomputed when the mutation cache notifies, so after a filter change the array keeps showing the old filters' results until something unrelated touches the cache. If nothing does, it stays wrong.

result.current is only written inside the mutationCache.subscribe() callback, and getSnapshot is () => result.current. So a render with new options recomputes nothing.

Same symptom as #11152 / #11153 in svelte-query, different cause.

Your minimal, reproducible example

N/A, reproduces in the package's own vitest suite.

Steps to reproduce

Add to packages/react-query/src/__tests__/useMutationState.test.tsx, run pnpm nx run @tanstack/react-query:test:lib -- useMutationState:

it('should update the result when mutation filters change without a cache update', async () => {
  const queryClient = new QueryClient()
  const key1 = queryKey()
  const key2 = queryKey()

  function Variables({ mutationKey }: { mutationKey?: Array<string> }) {
    const variables = useMutationState({
      filters: { mutationKey },
      select: (mutation) => mutation.state.variables,
    })

    return <div>variables: {variables.join(',')}</div>
  }

  function Page({ mutationKey }: { mutationKey?: Array<string> }) {
    const { mutate: mutate1 } = useMutation({
      mutationKey: key1,
      mutationFn: (input: number) => sleep(100).then(() => 'data' + input),
    })
    const { mutate: mutate2 } = useMutation({
      mutationKey: key2,
      mutationFn: (input: number) => sleep(100).then(() => 'data' + input),
    })

    React.useEffect(() => {
      mutate1(1)
      mutate2(2)
    }, [mutate1, mutate2])

    return <Variables mutationKey={mutationKey} />
  }

  const rendered = renderWithClient(queryClient, <Page mutationKey={undefined} />)

  await vi.advanceTimersByTimeAsync(0)
  expect(rendered.getByText('variables: 1,2')).toBeInTheDocument()

  rendered.rerender(<Page mutationKey={key1} />)

  expect(rendered.getByText('variables: 1')).toBeInTheDocument()
})

Both mutations stay pending, so the cache never notifies. Output stays variables: 1,2 instead of variables: 1.

Expected behavior

The array should always reflect whatever filters currently select, as it does in vue-query, angular and lit.

How often does this bug happen?

Every time

Platform

N/A, jsdom.

Tanstack Query adapter

react-query

TanStack Query version

v5.102.2

TypeScript version

v6.0.3

Start with the useMutationState implementation and its getSnapshot and mutationCache.subscribe logic, then add the regression case to packages/react-query/src/tests/useMutationState.test.tsx. Run pnpm nx run @tanstack/react-query:test:lib -- useMutationState. Done means the result updates from variables: 1,2 to variables: 1 when filters change without a cache update.