Custom syntax highlighting theme

[franknoirot]

We've been using the default syntax highlighting theme in light mode and the "oneDark" syntax highlighting theme in dark mode for a long time, and I've got some qualms with them:

Light mode

1. The comment color is a bit too noticeable and clashes with our UI, a sort of rusty red
2. Most of the text of KCL programs are either variable declarations or variable references, and all of these are bright blue
3. Function argument labels have the same appearance as variable declarations

Dark mode

1. There is very little differentiation between: variable declarations, variable references, function calls, and argument labels
2. The text is overwhelmingly red which is not really the color palette we use for the app otherwise

Over the weekend I tried out a first pass at a replacement light and dark theme. I'm not sold on my approach but I want to get it out to the team to give their feedback and adjustments, because now I should be able to make changes very easily.

Light

Before

After

Dark

Before

After

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Project	Deployment	Preview	Comments	Updated (UTC)
modeling-app	Ready	Preview	Comment	Nov 18, 2025 11:05pm

[franknoirot]

The unit tests are failing because I tried to wrap the unlabeled argument in KCL with a named grammar so I could somehow highlight it differently than labelled arguments, but I didn't find a way to do that at the end of the pipeline. I can remove that change if no one has ideas on how to get that highlighting to work, or if you think it's not worth trying to highlight them differently anyway.

[jtran]

You need to update the unit tests. I'm guessing the ones in this file, packages/codemirror-lang-kcl/test/call.txt, but anything that uses a call with an unlabeled arg in that directory.

[adamchalmers]

My only concern is that this looks a bit weird, I think it's too high contrast between the black and white and cyan. Maybe a darker shade of blue?

Other than that, this looks amazing. Great work!

[franknoirot]

Can do @jtran and @adamchalmers!

[franknoirot]

@jtran I opted to just drop my UnlabeledArgument because I couldn't get highlighting to work how I wanted for it and I didn't have a very clear idea to begin with. So I think the tests will likely pass now.

[franknoirot]

@adamchalmers how is this feeling now? I dropped the chroma and the lightness a bit.

[franknoirot]

I did break that E2E test, I'll debug in the AM