UI to add/remove channel subscribers

[chrisbobbe]

The legacy app doesn't quite offer a UI for this; it has an "Add subscribers" button, but that doesn't let you see who's currently subscribed, or let you remove subscribers (if you have permission for that):

The implementation should consult the appropriate group-based permissions to determine whether to offer this UI. See at least can_remove_subscribers_group, for removing subscribers; there may be more permission groups to check.

This UI will make the most sense when it starts from showing a list of the existing subscribers. So that UI, #1910, is a prerequisite for this issue.

Related issues

• Prerequisite: View subscribers of a channel #1910
• Edit some channel settings #1102

[chrisbobbe]

This came up in beta feedback on CZO:

In the new app, I don't see any way to unsubscribe / mute / notifications / add subscriber.

From a bundle of channel-related actions, this is one that that user said he'd miss most or use most frequently:

Primarily unsubscribe, pin, and add/check subscribers.

[rishichirchi]

I would like to work on this issue!

[chrisbobbe]

See issue description:

Like #1102, this won't be ripe to work on until we're set up to handle the new group-based permissions. See at least can_remove_subscribers_group, for removing subscribers; there may be more permission groups to check.

[alya]

Requested via X: https://x.com/ZhongboK/status/1896053797052641571

[chrisbobbe]

When this is done we should update the Help Center doc. We removed instructions for the legacy app when preparing to launch the new app: zulip/zulip@c1dd12b