PSReadLine doesn't respect cursor position when using `cmd+k` or `cmd+l` on macOS

[daprahamian]

Prerequisites

• [X] Write a descriptive title.
• [X] Make sure you are able to repro it on the latest released version
• [X] Search the existing issues, especially the pinned issues.

Exception report

N/A

Screenshot

https://github.com/user-attachments/assets/7b4612e4-e6ae-4fb5-b24d-b9aeefcdd429

Environment data

PS Version: 7.4.2
PS HostName: ConsoleHost
PSReadLine Version: 2.3.5
PSReadLine EditMode: Emacs
OS: Darwin Dans-MacBook-Pro.local 23.5.0 Darwin Kernel Version 23.5.0: Wed May  1 20:14:38 PDT 2024; root:xnu-10063.121.3~5/RELEASE_ARM64_T6020 arm64
BufferWidth: 80
BufferHeight: 24

Steps to reproduce

1. Set the following key handler

Set-PSReadlineKeyHandler -Chord 'Control+a' -ScriptBlock {
  [Console]::SetCursorPosition(5, 5)
}

2. Set prompt to null

function prompt { "`0" }

3. Clear screen. Your cursor should now be in the top left corner

Clear-Host

4. Hit Ctrl+a. Your cursor should now be at position 5,5

5. Type Write-Output

Expected behavior

The shell would display Write-Output starting at position 5,5

Actual behavior

The cursor moves back to position 1,1 and displays Write-Output there

[daxian-dbw]

PSReadLine doesn't handle the case where the cursor is moved from outside of PSReadLine (cursor movement from a custom key handler is also considered outside of PSReadLine). It doesn't simply write at the current cursor position but tracking the initial cursor position and calculate where it should render for the text. So, I'd say the reported scenario is not supported.

[daprahamian]

Thanks for the reply @daxian-dbw. In that case, what is the proper mechanism for adjusting the cursor position of PSReadline?

[daxian-dbw]

PSReadLine's cursor position is supposed to be adjusted only by its cursor movement key bindings, such as Home, End, LeftArrow, Ctrl+LeftArrow, and etc.

[daprahamian]

that seems like a pretty limited view of what one can do in a terminal, and by extension what PSReadline should be obligated to handle. There are multiple cases when a terminal application can change the position of the cursor, and it seems like a poor user experience to ignore those.

As another example, hitting Cmd+K or Cmd+L in the Mac terminal app clears the screen, and in the case of Cmd+K moves the cursor to the top of the screen along with a fresh prompt. PSReadline does not respect this and continues typing in the last location.

It seems like PSReadline should either respect the current cursor position within the terminal, or it should have an API that allows the cursor position to be moved.

[daxian-dbw]

PSReadLine handles cursor movement due to resizing of the terminal window and a special case where a TUI clears the screen (see code here). But unfortunately, it doesn't handle cmd+k and cmd+l on mac. I'm not sure if we can perfectly support cmd+k because PSReadLine allows multi-line input and if the cursor is in the middle of a multi-line input, cmd+k will only keep the line where the cursor is at. It looks zsh doesn't handle that case well either.

But I think we should support cmd+k and cmd+l if there is no input yet or if the input fits in the current row on terminal.