default props for roots/joins

[myguidingstar]

so that

[{:person/by-id] :my/join}]
;; or
[{:person/by-id] [{:my/join [*]}]]
;; will behave just like:
[{:person/by-id] [{:my/join [:pre/defined :default/props]}]]

[myguidingstar]

this should be implemented as a wrap-read that expand the provided query repeatedly until no more change

[myguidingstar]

with the new public api, the necessary data is already available (as the root/join's :output)