Support for "higher order" route handlers and wrapping createFileRoute

[dhleong]

Following up on the discussion here, my team has recently stumbled onto a case where it would be useful to be able to wrap a route and do a few things:

1. Do an extra data load in parallel with whatever the route is loading
2. Unwrap this extra data
3. Plumb the data into a <Context.Provider> component wrapping whatever component the route originally intended to use, to make the data available to child components via hook

Something like one of these seems intuitive, but unsupported due to tanstack compiler and automatic code splitting constraints:

// Call the function to create a wrapper, wrap the `createFileRoute` function result:
createExperimentRoute('experiment-id')((createFileRoute(...))({
  // ...
});

// Wrap `createFileRoute` and augment the params it accepts
// Less ideal probably, because the types kind of "fight"
createExperimentRoute(createFileRoute(...))({
  experimentId: 'experiment-id',
  // ...
});

My understanding from the discussion on Discord is that there is interest in supporting this type of capability but it is not ready—would love to learn if there's still interest, what the constraints are, and if there's anything I can do to help 🙏

[schiller-manuel]

it's very much a feature we want to support. just bandwidth didnt allow to build it yet