The more advanced features SyncTERM gets, the less useful the scrollback buffer becomes. Replacing this with a timeline instead, which basically keeps the whole stream contents with the exception of file transfers, and generates the occasional "I frame" for more efficient display (possibly based on a cumulative "render time" metric).
Being able to save these and play them back could also have a large number of unexpected benefits.
Anonymous
For proper replay-ability, the time domain would need to be captured as well, potentially making this a much larger storage format.
Global state "stuff" (ie: cached files) will need to be dealt with for replays as well.
Possibly add debug/log data into it as well.
Note that the interface needs to be at least as convenient for common use-cases (scrolling back to original message when replying, etc).
Clipboard-copy functionality is (for text) is my main use case for scroll-back