Display a counter next to each relay showing how many contacts depend on it

[bencan]

When switching to a new relay it is helpful to know if any of your contacts only know about your old relay before you delete it.

To make it easier to know if it is safe to delete an old relay, I suggest adding a counter next to each relay when you open the relay settings which shows how many of your contacts depend on the relay (because they don’t know about your other relays) for example “6 of your contacts only know about this relay”. If the counter is zero then you know it is safe to delete.

Ideally if you tap the counter, it will then show you exactly which contacts depend on this relay, so you know which contacts you need to message from your new relay, or delta chat will offer to send them all an automatic message.

Here are some examples of real use cases where this would help:

Example 1

@tmattei

I’m thinking of deleting the malfunctioning relay altogether. I already selected a different one for sending. I’ve read in the FAQ’s that

If you remove a relay, contacts who only know this relay may not reach you until you message them again. To stay reachable in the meantime, choose Hide from Contacts in the confirmation dialog instead of removing it right away.

So, if I send a message to all of my contacts, I should be safe removing it, is it right?

Example 2

@stbaeumer

I switched from posteo.de to chat.vim.wtf. I now have both servers listed under “Relays”, but only vim.wtf is enabled.
My questions are:

1. Can I delete posteo.de after some time?

Expected behavior

When you open the relay settings you can see with one glance if a relay is safe to delete or if some of your contacts still depend on it. Each relay displays a counter next to it showing you how many of your contacts depend on it.

Actual behavior

To know how many of your contacts depend on a specific relay, you have to open each chat and manually inspect read receipts or replies which is time consuming and error prone.