How can a different vscode Extension connect to the csharp Extension?

[CodeDevAM]

I want to write a vscode extension that requires input from the csharp extension. How can I find the right instance and how can I connect to it?

[dibarbet]

If you want to just get the results of built in features (e.g. go to definition, find references), you can use the VSCode command API to invoke the relevant commands. This is what we do in integration tests for example - https://github.com/dotnet/vscode-csharp/blob/main/test/lsptoolshost/integrationTests/gotoDefinition.integration.test.ts#L39

If you wish to access Roslyn's Solution / Symbols / SyntaxTrees etc, we unfortunately do not yet have a public API for that yet. We are planning to expose a plugin model where you can write a plugin that runs in the Roslyn LSP process and allow you to query Roslyn APIs.
See also dotnet/roslyn#68696

[CodeDevAM]

Having such a public API would be awesome.