DocC Language Features in SourceKit-LSP

Greetings! My name is Aditya Bhushan and I am a third-year Computer Science student with a strong interest in Swift development and developer tooling. I am a Swift Student Challenge 2025 winner which motivated me to explore deeper contributions to the Swift ecosystem.

While preparing for GSoC, I studied the DocumentationLanguageService module and related components such as swift-markdown and IndexStoreDB. During this process, I submitted a few small fixes to SourceKit-LSP:

#2571 - Simplified MarkdownTitleFinder.visitHeading using SymbolLink.destination
#2572 - Fixed incorrect error type in encode(_:) and corrected a typo
#2573 - Fixed testEmptyActor using class instead of actor declaration

I have prepared a GSoC proposal titled “DocC Language Features in SourceKit-LSP,” focusing on adding semantic tokens, go-to-definition, diagnostics, and preview link navigation for DocC documentation files.

I would greatly appreciate any feedback on the proposal particularly regarding scope realism, architectural risks or areas that may need refinement.

Proposal draft: Gsoc - Google Docs

Thank you for your time and guidance.

@ahoppen @matthewbastien - I would be grateful for any feedback or suggestions.