DIY shell integration with kitty / WezTerm

[adam-c-anderson]

Hi, I'm a PowerShell fan who has replaced my Windows workstation with a Mac. I started out using iTerm2, but found MenuComplete rendering distractingly slow, so I've been exploring other faster terminals including kitty and WezTerm, and in going over their docs I've noticed that they both offer additional functionality via "shell integration" for Bash, Zsh, and Fish.

I'd love to try to implement the protocol myself if possible to add shell integration for PowerShell, but I'm not sure if I have enough control to fully implement either spec. The kitty docs give a quick overview of what kitty requires, but in short I need to inject ANSI escape codes in the following places:

1. Before the PS1 (standard) prompt renders. I'm confident I can do this by overriding the prompt function.
2. Before the PS2 (continuation) prompt renders. I think it should be possible to do this by overriding the prompt function, but I'm not sure exactly how yet. Answers welcome!
3. Just before command output starts. I think I might be able to do this by creating custom Format.ps1xml files and loading them in my profile file. Is this feasible?
4. Optionally, right after a command exits. I think I might be able to do this either by customizing the formatters or by doing it right at the start of the prompt function. Which choice would work better?

[adam-c-anderson]

Follow-up: I determined that I could fully implement kitty's shell integration needs with the following:

1. Override the prompt function to output <OSC>133;A<ST>
2. Use Set-PSReadLineOption -ContinuationPrompt to output <OSC>133;A;k=s<ST>
3. Override Out-Default to both output <OSC>133;C<ST> and <OSC>133;D;<exit_code><ST> in the appropriate places
   a. I delegated to the original Microsoft.PowerShell.Core\Out-Default in the body
   b. It was important to defer calling the original Out-Default until the end block to preserve correct output-formatting behavior