Multi Fetch GET with /full option?

[bhousel]

Per openstreetmap/iD#6668 (comment)
iD is using the Multi Fetch GET API call in a few situations to fetch ways and relations:

• downloading additional member ways for correct handling of multipolygons, routes, etc.
• checking and dealing with error 409 conflicts at save time

Unfortunately we need to still perform more calls after this to get all the related nodes (and this can be a lot of nodes).

It would be really great if we could have a version of this call that works like the /full Single Fetch GET call that returns all the related nodes in the response.

cc @mmd-osm

[gravitystorm]

Seems reasonable to me.

[mmd-osm]

As I mentioned in the linked issue, we still need to sort out, how the new "multi fetch with full option" is exposed via the API. Should we extend the existing endpoint (if so, how exactly should that look like?), or would it make more sense to define a new endpoint?
That's more or less the same level of detail you would need to update the OSM API documentation in the WIki.

[pnorman]

As I mentioned in the linked issue, we still need to sort out, how the new "multi fetch with full option" is exposed via the API. Should we extend the existing endpoint (if so, how exactly should that look like?), or would it make more sense to define a new endpoint?

Any opinions on this from those who want the new endpoint?