notify admins of state-changing commands

Value

As one of many admins, I would like to know when another admin has performed an action that modifies the state of my channel so I can communicate with other admins about it if needed and not be caught off guard.

Behavior

GIVEN a channel with admins

• WHEN any of the following commands are successfully executed: RENAME/RESPONSES ON-OFF/ADD/HELLO/GOODBY
• OR WHEN an admin issues GOODBYE
• THEN notify all admins with an appropriate notification message

Definitions

• notification for ADD/REMOVE says `Another admin was just {added/removed}.'
• notification for RENAME says The channel was renamed from {old name} to {new name}.
• notification for RESPONSES ON / OFF says Responses were turned on Responses were turned off
• notification for an admin issuing GOODBYE says An admin just left the channel

All of the above assumes we want to keep admin phone numbers out of notification messages.

Scoping Notes

• if time permits: make it possible to toggle HELLO/GOODBYE notifications on/off