What the team inbox plugin needs, kept general for other plugins:
- `api.ui.setListFilters`: keyword filters drawn as chips in the list
header of the folders they apply to (by account kind and folder
role). A chip the user turns on is ANDed into the folder's query and
comes off with one click; a keyword change a filter tests loads the
list again (ui:message-list).
- Actions get `accounts`, `hasKeyword` and `notKeyword`, so a button
shows only on messages of group accounts, or of a keyword state; the
click of message-row-actions and reader-actions carries the message's
`accountId`.
- `api.email.updateKeywords`: several keywords in one change, through
the list for a listed message (email:write).
- `api.user.getSelf`, `getMailAccounts` and `findPeople`: the user's own
account id (Stalwart's principal id), which accounts are group
accounts, and people from the directory (account:read).
- `api.accountData`: a plugin's own entry in a mail account's shared
Inbox metadata on Stalwart 1.0 (email:read / email:write).
- Row badges take an `icon`.