My case is the following. I have an .ics file in a delta chat conversation (which further, was developed with mini app meet up). When I try to open it, if I have not chosen a default app for opening ics files it offers the distinct calendar apps I have installed in my (Android derived /e/OS) system.
However, it does not offer the mini app calendar, which I have also included in the same conversation.
Would it be possible that trying to opening files included in conversations detect suitable mini apps included in the same conversations too? Or may this be more a bug for the calendar app than a feature request for Delta Chat?
Interesting idea.
At least on Desktop these protocol handlers are usually declared when the app gets installed (although I think it’s still possible to add them dynamically).
Implementation-wise one would first have to declare that Delta Chat handles a specific protocol, and then route the links to a specific WebXDC app instance.
Personally to me this doesn’t sound too exciting TBH.
Let me address your individual questions separately.
The calendar webxdc app already supports importing a .ics file. Instead of clicking on the .ics attachment, export it as a file on the device from the timeline, open the calendar app, and then browse the file from the file picker to put it into your calendar.
One may consider proposing to declare in the webxdc manifest any protocol handlers it can define. Then subject to confirmation on first use in DC, it could apply to either intents coming from the same group, same profile or anywhere within DC. protocol_handlers - Web app manifest | MDN
One may consider a feature request for DC clients to declare serving OS-level protocol handlers backed by webxdc selected by the user.