feat: add text selection across multiple text views (MVP)

[Tnixc]

Screen.Recording.2026-02-01.at.20.52.18.mov

theres a tiny bug regarding the lines when selecting wildly. otherwise very usable.

[Copilot]

Pull request overview

This PR adds cross-block text selection functionality for markdown text on macOS, allowing users to select text across multiple markdown blocks in a single selection. This is an MVP (Minimum Viable Product) implementation that improves the user experience when copying text from messages.

Changes:

• Added new SelectableMarkdownText component that combines multiple markdown blocks into a single selectable NSTextView
• Modified MarkdownText to conditionally use the new selection mode via an environment value on macOS
• Enabled cross-block text selection in MessageBody by default for message content

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
SelectableMarkdownText.swift	New component implementing multi-block text selection using NSTextView with custom clipboard handling for Discord markdown
MarkdownText.swift	Added environment key and conditional rendering to support cross-block selection mode on macOS
MessageBody.swift	Enabled the cross-block text selection feature for message content

[llsc12]

These changes make MarkdownText ignore block elements, meaning things like codeblocks, lists and more do not show up anymore.

[llsc12]

For now, it might be best to look into this later since it seems a lot more difficult to tackle than anticipated. Tagging as help needed.

[Tnixc]

yes help wanted indeed.

i built a small prototype with NSAttributedString with code blocks.

Since HighlightSwift already has an option to return NSattributed text, this is fine. Lists shouldn't be too hard, looks like NSAttributedString has built-in styling for it

the problem is with the codeblock styling, I have to create a custom model with ObservableObject to read the rects of the code and return/update where to draw the background and to put the copy button (feels more complicated than it has to be)

This is probably not inexpensive but I think it's possible to get away with it if we only do it for the content onscreen. If this really tanks performance i hope we could have a toggle (which shouldn't be hard since none of this will be on iOS anyway?)

And for custom emojis I think I can use NSTextAttachment.

I think with how this is going there is no chance of cross message select, which is unfortunate