Does Android's built-in SQLlite support Stored Procedures? SP would be a good way 1) to give only limiled access to other apps to the database 2) as a level of abstraction, in case the database scheme needs to get changed in Transito.

android-specific way to do this / share a common filepath (atleast as RO)

that would be great!

But that would mean two have to copies of the gtfs database on the android device? one in the transito app, another one in the compiled c-library?

transito feature request: local API, for other Apps running on the same device, so that they can query Transito locally for nearby stations or stations for given coordinates.

maybe routes and connecitons also. Or translating a given station name to coordinates.

The "Öffi" app does a search for nearby stations, but only online, not offline. If Transito is installed on a device, an other App could locally search for nearby stations, if transito offers the function through some API.

probably the same feed, that privously did not import because of the vis-a-vis string.

front end could also be a smart watch (either wear os , or chinese smart watch with Android8++)

(2) + limited storage capcity

probably quouting is needed during import of gtfs data

transito installed on two devices: the one with more storage and computing power is the backend, the other is the front end with GUI.

On the frontend are only the station names downloaded.

Frontend and backend app connected by bluetooth/wiki/usb.

check for updates of installed gtfs feeds by sending a http-head request for the feed, then check the http-response for changed values for content-length and last-modified http-response headeers. then offer to update all feeds that have changed.