This PR includes:
* Implemented core signature help logic
* Added new docstring method on Definition that returns a docstring for
function and class definitions
* Modified the display code for Signature that allows a signature string
to be broken into text ranges that correspond to each parameter in the
signature
* Augmented Signature struct so it can track the Definition for a
signature when available; this allows us to find the docstring
associated with the signature
* Added utility functions for parsing parameter documentation from three
popular docstring formats (Google, NumPy and reST)
* Implemented tests for all of the above
"Signature help" is displayed by an editor when you are typing a
function call expression. It is typically triggered when you type an
open parenthesis. The language server provides information about the
target function's signature (or multiple signatures), documentation, and
parameters.
Here is how this appears:

---------
Co-authored-by: UnboundVariable <unbound@gmail.com>
Co-authored-by: Micha Reiser <micha@reiser.io>
This PR implements a basic semantic token provider for ty's language
server. This allows for more accurate semantic highlighting / coloring
within editors that support this LSP functionality.
Here are screen shots that show how code appears in VS Code using the
"rainbow" theme both before and after this change.


The token types and modifier tags in this implementation largely mirror
those used in Microsoft's default language server for Python.
The implementation supports two LSP interfaces. The first provides
semantic tokens for an entire document, and the second returns semantic
tokens for a requested range within a document.
The PR includes unit tests. It also includes comments that document
known limitations and areas for future improvements.
---------
Co-authored-by: UnboundVariable <unbound@gmail.com>
## Summary
This PR adds initial support for workspace diagnostics in the ty server.
Reference spec:
https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#workspace_diagnostic
This is currently implemented via the **pull diagnostics method** which
was added in the current version (3.17) and the server advertises it via
the `diagnosticProvider.workspaceDiagnostics` server capability.
**Note:** This might be a bit confusing but a workspace diagnostics is
not for a single workspace but for all the workspaces that the server
handles. These are the ones that the server received during
initialization. Currently, the ty server doesn't support multiple
workspaces so this capability is also limited to provide diagnostics
only for a single workspace (the first one if the client provided
multiple).
A new `ty.diagnosticMode` server setting is added which can be either
`workspace` (for workspace diagnostics) or `openFilesOnly` (for checking
only open files) (default). This is same as
`python.analysis.diagnosticMode` that Pyright / Pylance utilizes. In the
future, we could use the value under `python.*` namespace as fallback to
improve the experience on user side to avoid setting the value multiple
times.
Part of: astral-sh/ty#81
## Test Plan
This capability was introduced in the current LSP version (~3 years) and
the way it's implemented by various clients are a bit different. I've
provided notes on what I've noticed and what would need to be done on
our side to further improve the experience.
### VS Code
VS Code sends the `workspace/diagnostic` requests every ~2 second:
```
[Trace - 12:12:32 PM] Sending request 'workspace/diagnostic - (403)'.
[Trace - 12:12:32 PM] Received response 'workspace/diagnostic - (403)' in 2ms.
[Trace - 12:12:34 PM] Sending request 'workspace/diagnostic - (404)'.
[Trace - 12:12:34 PM] Received response 'workspace/diagnostic - (404)' in 2ms.
[Trace - 12:12:36 PM] Sending request 'workspace/diagnostic - (405)'.
[Trace - 12:12:36 PM] Received response 'workspace/diagnostic - (405)' in 2ms.
[Trace - 12:12:38 PM] Sending request 'workspace/diagnostic - (406)'.
[Trace - 12:12:38 PM] Received response 'workspace/diagnostic - (406)' in 3ms.
[Trace - 12:12:40 PM] Sending request 'workspace/diagnostic - (407)'.
[Trace - 12:12:40 PM] Received response 'workspace/diagnostic - (407)' in 2ms.
...
```
I couldn't really find any resource that explains this behavior. But,
this does mean that we'd need to implement the caching layer via the
previous result ids sooner. This will allow the server to avoid sending
all the diagnostics on every request and instead just send a response
stating that the diagnostics hasn't changed yet. This could possibly be
achieved by using the salsa ID.
If we switch from workspace diagnostics to open-files diagnostics, the
server would send the diagnostics only via the `textDocument/diagnostic`
endpoint. Here, when a document containing the diagnostic is closed, the
server would send a publish diagnostics notification with an empty list
of diagnostics to clear the diagnostics from that document. The issue is
the VS Code doesn't seem to be clearing the diagnostics in this case
even though it receives the notification. (I'm going to open an issue on
VS Code side for this today.)
https://github.com/user-attachments/assets/b0c0833d-386c-49f5-8a15-0ac9133e15ed
### Zed
Zed's implementation works by refreshing the workspace diagnostics
whenever the content of the documents are changed. This seems like a
very reasonable behavior and I was a bit surprised that VS Code didn't
use this heuristic.
https://github.com/user-attachments/assets/71c7b546-7970-434a-9ba0-4fa620647f6c
### Neovim
Neovim only recently added support for workspace diagnostics
(https://github.com/neovim/neovim/pull/34262, merged ~3 weeks ago) so
it's only available on nightly versions.
The initial support is limited and requires fetching the workspace
diagnostics manually as demonstrated in the video. It doesn't support
refreshing the workspace diagnostics either, so that would need to be
done manually as well. I'm assuming that these are just a temporary
limitation and will be implemented before the stable release.
https://github.com/user-attachments/assets/25b4a0e5-9833-4877-88ad-279904fffaf9
## Summary
This PR makes the necessary changes to the server that it can request
configurations from the client using the `configuration` request.
This PR doesn't make use of the request yet. It only sets up the
foundation (mainly the coordination between client and server)
so that future PRs could pull specific settings.
I plan to use this for pulling the Python environment from the Python
extension.
Deno does something very similar to this.
## Test Plan
Tested that diagnostics are still shown.
## Summary
PR adding support for it in the VS Code extension:
https://github.com/astral-sh/ty-vscode/pull/36
This PR adds support for `python.ty.disableLanguageServices` to the ty
language server by accepting this as server setting.
This has the same issue as https://github.com/astral-sh/ty/issues/282 in
that it only works when configured globally. Fixing that requires
support for multiple workspaces in the server itself.
I also went ahead and did a similar refactor as the Ruff server to use
"Options" and "Settings" to keep the code consistent although the
combine functionality doesn't exists yet because workspace settings
isn't supported in the ty server.
## Test Plan
Refer to https://github.com/astral-sh/ty-vscode/pull/36 for the test
demo.
Specifically, this PR reverts "Make completions an opt-in LSP feature
(#17921)",
corresponding to commit 51e2effd2d.
In practice, this means you don't need to opt into completions working
by enabling experimental features. i.e., I was able to remove this from
my LSP configuration:
```
"experimental": {
"completions": {
"enable": true
}
},
```
There's still a lot of work left to do to make completions awesome, but
I think it's in a state where it would be useful to get real user
feedback. It's also meaningfully using ty to provide completions that
use type information.
Ref astral-sh/ty#86
## Summary
This PR updates the language server to avoid panicking when there are
multiple workspace folders passed during initialization. The server
currently picks up the first workspace folder and provides a warning and
a log message.
## Test Plan
<img width="1724" alt="Screenshot 2025-05-17 at 11 43 09"
src="https://github.com/user-attachments/assets/1a7ddbc3-198d-4191-a28f-9b69321e8f99"
/>
## Summary
We now expect the client to send initialization options to opt-in to
experimental (but LSP-standardized) features, like completion support.
Specifically, the client should set `"experimental.completions.enable":
true`.
Closes https://github.com/astral-sh/ty/issues/74.