I would like to request both IRCv3's echo-message and batch capabilities to be added, namely because of an issue we've been experiencing when using recent git checkouts of ZNC.

Since a specific commit they've started to time stamp *all* messages (the server-time CAP), while previously only the buffer playback was time stamped. This new behavior is leading to inconsistent times being shown to the user.
An example:
Code:
[15:05:33] <timetester> hi
[15:04:36] <timewizard> hey, timetester
[15:05:49] <timetester> how are you today?
[15:04:53] <timewizard> i'm fine, and you?
[15:06:04] <timetester> just got home from...

timetester is a remote user, and timewizard is the user connected to ZNC. This issue also happens for other events, such as quits, kicks, etc.
In the example the clock is behind by almost a full minute, but even a few seconds is an annoyance if you're active on IRC (chatting while others are also active).

It's been said that implementing echo-message can solve this problem.

Alternatively it's also been said that implementing batch support may also solve the problem, because then we could have a client-side script listen for the end of the batch and then send a "CAP REQ :-server-time" when we receive it, though I don't like this solution much since it is a workaround, it's better than nothing.

An issue about this was opened here but has been closed: https://github.com/znc/znc/issues/1144
Please read the full issue thread first before commenting here about fixing clocks and keeping them synced, as it's already been discussed over there and is not a foolproof solution.