fix(ex.lsp.single): replace deprecated get_buffers_by_client_id

[icalvo]

Summary

• Replace vim.lsp.get_buffers_by_client_id() with client.attached_buffers in ex.lsp.single
• Update tests to set attached_buffers on mocked clients instead of stubbing the deprecated API

Fixes the Neovim 0.12 deprecation warning (removed in 0.13) shown when the statusline refreshes after LSP attach.

Test plan

• make test only=components/lsp_spec.lua
• Open a file with LSP attached and confirm no get_buffers_by_client_id warning in :checkhealth vim.deprecated

Made with Cursor

[icalvo]

It's doing fine on my local. Also I understand you may want backwards compat, but maybe you can open a branch for 0.13. Also I know it's AI and you can throw it to the bin for that reason, np!

[vladimir-popov]

@icalvo Thanks for the PR! AI-generated code is not a problem by itself. I only care about the final
result.

Right now the formatting check is failing, as well as the test
ex.lsp.single component on draw should not create highlight for the different client with the same name.
Please fix them.

I also do not see an obvious backward compatibility issue. The project targets
Neovim 0.10+, and client.attached_buffers is available there. Could you clarify what exactly you expect to break, and in which Neovim version or usage scenario?

[icalvo]

I didn't expect anything either way; I am just not knowledgeable enough about Neovim to know if the new API has been there long enough not to break any version you support.

[vladimir-popov]

@icalvo Good job! Thank you!