How was integration for you guys? Was the integration easier for you guys since you have an established emacs system consuming terminal output with reasoned semantics over what goes where for existing subsystems (rendering, osc codes, etc)?

For libghostty-vt, since you're targeting a terminal TUI instead of an external subsystem (for example; for ghostty, you hit libghostty-vt -> GPU rendering, which is external), you still have to buy into terminal semantics. in my experience, since I was trying to replicate mosh with libghostty-vt as the parser, what happened was that my optimized re-rendering kept getting increasingly coupled to terminal semantics (and the UDP state update model too), otherwise I'd have to send the entire terminal grid over the network like, every time.

What are the tricks for making this both performant and not like, utter cancer? You have a harder issue here too (similar to tmux) in that certain optimizations are just not available to you, or you have to translate (literally geometrically) certain instructions

I'm not entirely sure what you're asking. But I'll answer to the best of my abilities:

For Ghostel, libghostty-vt is the source of truth and the architecture is essentially that we serve input to the PTY and the PTY serves output to libghostty-vt which builds out the state in the form of a terminal screen structure. The goal is then to keep the contents of an Emacs buffer up to date to this terminal screen without replace the entire thing every time we redraw. We make use of mainly two things in order to do as little work as possible: - Scrollback is immutable and thus never has to be modified unless it's evicted, alt screen is activated, dimensions change etc. - libghostty-vt maintains row level dirty flags that we scan to make sure we're only replacing lines that have actually changed.

So for the rendering part, we're only diffing the grid state against the buffer, not doing anything based on terminal semantics per se, parser events that draw to the screen are passed straight to the terminal handler. But of course, certain things we need to hook into such as directory and title changes, of clipboard events etc.

Might also add that we're using the direct Zig API, not the C API, which means we have access to things that aren't exposed in the C API.