Custom channels list

I would like to implement a channels list which contains not only the channel topic and number of users, but also show things like how active the conversation is, the current mood/vibe of the channel, as well as a short summary of the channel conversation, updated periodically.

There are also other things to consider such as if I want to mark a channel as "nsfw" for example, and be able to include or filter these explicitly in results.

I have a few considerations with regards to server-side implementation:

• METADATA - By setting this information as channel METADATA we could, as a client, query each value for each channel as they are received by the client. The problem with this is that could take a while to render depending on the size of the channels list.
• Message Tags - By including values in the Message Tag body, prefixed to the 322 numeric, we can easily reference all the data we need about a channel for the list frame by frame, meaning rendering might still be a little bit slow but each result will already be fully-formed. This also means we would need to implement some custom commands to set and change the values and propagate them to the client later in some new invented format.

I think we should go for a mix of both of these for most things, i.e. a channel operator could set the channel as nsfw using METADATA, which a user won't need to subscribe to but can still be shown in the channels list via tags, or maybe something like music or channel icon/avatar which a user could subscribe to and also show in the channels list via tags.

Start by tracing the existing channel-list handling and the IRC 322 numeric in the TypeScript client and server-related code. Compare the proposed METADATA and message-tag approaches, including how channel operators would set values and how clients would filter them. Done means a defined, implemented, and documented channel-list format supporting the requested metadata and filters.