Add support for copying math source from katex blocks

[pwang347]

Screenshot

Fixes #258286

[Copilot]

Pull Request Overview

This PR adds support for copying LaTeX source code from KaTeX math elements in chat responses. Users can now right-click on rendered math formulas and select "Copy Math Source" to get the underlying LaTeX code.

Key changes:

• Adds a new context key to detect when KaTeX math elements are focused
• Implements context detection for KaTeX elements in the chat widget's context menu
• Creates a new action to extract and copy LaTeX source from KaTeX annotations

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/vs/workbench/contrib/chat/common/chatContextKeys.ts	Adds new context key isKatexMathElement to identify when KaTeX elements are focused
src/vs/workbench/contrib/chat/browser/chatWidget.ts	Implements KaTeX element detection in context menu handler and sets the context key
src/vs/workbench/contrib/chat/browser/actions/chatCopyActions.ts	Adds new "Copy Math Source" action that extracts LaTeX from KaTeX annotation elements

[mjbvz]

Seems reasonable to me. Thanks for looking into this!

[Tyriar]

Looks a little fragile to me, but @mjbvz had a look

[pwang347]

Looks a little fragile to me, but @mjbvz had a look

Happy to discuss any changes you think would improve the stability here! Probably would be nicer to not have to do the closest call twice, but this fit cleaner into the existing action framework imo without needing to forward args.

[Tyriar]

Dealing with classes like this is basically touching internals of katex that could change in the future and therefore brick this feature on our end without any indication. Unless they have committed to the DOM structure that is.

[pwang347]

Dealing with classes like this is basically touching internals of katex that could change in the future and therefore brick this feature on our end without any indication. Unless they have committed to the DOM structure that is.

That makes sense, to my knowledge the class name has been around basically since the beginning so it should be relatively stable (but not guaranteed). This is good feedback though, I can check if we can inject a custom attribute at the same element and use that instead in a follow-up PR. Thanks!

Edit: I did some more research, and it doesn't seem trivial to inject custom attributes or class names without hacky methods like string replacements or parsing. Given that we version lock the KaTeX component, I think it would be safer to leave it as is and make sure that whenever we update KaTeX that we also validate these scenarios. That being said, since the class name has been around for a long time I suspect that we should be safe for quite a while.

[Tyriar]

A custom attribute with the source would be more reliable. We do lock it, but we don't go and verify every little feature on upgrading.