Prototype: Detect dark/light asynchronously

[bash]

No description provided.

[the-mikedavis]

https://github.com/contour-terminal/contour/blob/master/docs/vt-extensions/color-palette-update-notifications.md sounds like a good approach to me. We should be able to add support for enabling mode 2031 and receiving colorscheme change events in crossterm. With that there's no need to add any extra dependencies (especially platform-specific ones like in dark-light) - we can vendor or reimplement the perceived lightness function from terminal-colorsaurus instead.

Your patch to crossterm is small but for a proper implementation I think we should be adding a crossterm event which exposes the changed color(s) (similar to the resize event for example). Crossterm should ideally not be exposing escape sequences to consuming applications. I can take a look at writing a patch like that in the new year unless you'd like to give it a go.

edit: I actually took a swing at this already in #12362

[bash]

The contour extension is amazing 😍—and it's even supported by Kitty and Ghostty.

Your patch to crossterm is small but for a proper implementation I think we should be adding a crossterm event which exposes the changed color(s) (similar to the resize event for example).

Agreed, exposing the OSC String directly was the easiest way for me to experiment :)

Regarding terminal-colorsaurus: My goal with bash/terminal-colorsaurus#30 was to expose xparsecolor in a way such that if you depend on colorsaurus with default-features = false you get no extra dependencies. So vendoring should not be necessary :)

edit: I decided to publish the xparsecolor stuff as a separate mini-crate: https://docs.rs/xterm-color/