Implement `textDocument/selectionRange` to enable language-aware smart select in VS Code

[JulzDave]

Feature request: LSP textDocument/selectionRange support

Background

VS Code has a built-in “smart select” feature (triggered by Alt+Shift+Right Arrow) which incrementally expands the selection to the next larger syntactic block — for example:

• inside an expression ➔ whole statement ➔ surrounding method ➔ class ➔ file.

For many languages (like TypeScript or Python), this is powered by the language server implementing the LSP textDocument/selectionRange capability. This allows editor selection to be fully syntax-aware.

The problem with C# today

In C# (via OmniSharp), smart select is limited because textDocument/selectionRange is not implemented. This causes:

• Selections to jump from inside a function directly to selecting the entire file.
• No granular expansion from expression ➔ statement ➔ block ➔ method ➔ class.

This significantly reduces editing productivity compared to other languages in VS Code.

Why this belongs here

OmniSharp acts as the language server backbone for C# in VS Code, including with the new C# Dev Kit. Thus, implementing selectionRange here would immediately benefit all VS Code users working with C#.

Proposal

Please consider adding support for the textDocument/selectionRange LSP request in OmniSharp. This would allow:
✅ Incremental, syntax-aware selection expansion in VS Code.
✅ Consistency with other language experiences in the editor.
✅ Improved developer ergonomics.

References

• LSP spec: selectionRange
• VS Code command: editor.action.smartSelect.expand
• Example implementation for TypeScript: typescript-language-server

Thank you very much for considering this improvement!