file lock or checkout (REST) api to prevent overwriting and deletion
people can make one drive file editor
by using download/upload api
or file picker
or file handler addin.
but there is no way to lock/unlock or checkout/checkin files.
so concurrent modification of user A can be overwrited by user B right after.
Carlos Guzman commented
That's correct, we need this feature exposed in the API. The functionality is already there because the webdav interface and the windows client are locking the file when somebody is editing it.