Implement PythonTA LSP by a1-su · Pull Request #9 · pyta-uoft/python-ta-vscode-extension

a1-su · 2026-07-21T06:57:35Z

Proposed Changes

This PR introduces a simple implementation of the PythonTA LSP server, instead of manually running it from a keyboard command. However, it does not include the option to configure your changes yet, so that is a future extension.

Type of Change

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Type	Applies?
🚨 Breaking change (fix or feature that would cause existing functionality to change)
✨ New feature (non-breaking change that adds functionality)	X
🐛 Bug fix (non-breaking change that fixes an issue)
🎨 User interface change (change to user interface; provide screenshots)
♻️ Refactoring (internal change to codebase, without changing functionality)
🚦 Test update (change that only adds or modifies tests)
📦 Dependency update (change that updates a dependency)
📖 Documentation update (change that updates documentation)
🔧 Internal (change that only affects developers or continuous integration)

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I have performed a self-review of my changes.
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Questions and Comments

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david-yz-liu

@a1-su nice work, I left a few comments and also please resolve the merge conflicts (from your previous PR).

david-yz-liu · 2026-07-21T17:10:01Z

        return uris.to_fs_path(file_uri)
    return uris.to_fs_path(document.uri)

-


Revert this change

david-yz-liu · 2026-07-21T17:10:16Z

    # _run_tool_on_document and _run_tool functions as needed for your project.
    result = _run_tool_on_document(document)
-    return _parse_output_using_regex(result.stdout) if result.stdout else []
-


Revert this change (keep the blank line)

david-yz-liu · 2026-07-21T17:12:35Z

+            content = content[json_start:]
+
+        results = json.loads(content)
+        for file_result in results:


Overall I think this code can be simplified using lsp.converters.get_converter(). This returns a cattrs converter that should be usable to parse the JSON into the relevant lsp classes, since the PythonTA reporter should be set up using them already.

david-yz-liu · 2026-07-21T17:13:35Z

    # Pass document so get_cwd can resolve file-related variables for this document.
    cwd = get_cwd(settings, document)

+    if settings["interpreter"] and len(settings["interpreter"]) > 0:


I'm not sure why you changed the logic in this part of the code from what the template already provides. Let's just stick with the template here, we can always extend it later if we want.

I completely agree we should stick with what the template provides, but I believe for PythonTA to function correctly, adding this block of code might be necessary? For reference, here is the fatal error from PythonTA that we get when we run the extension without these lines:

And the file is also missing all the PythonTA-specific errors that we would see if we were to run PythonTA on the code normally. These are the only errors we see when we run the extension without this block of code:

And these are all the errors we should be seeing (matches what we would see in an HTML output) when PythonTA is run with this block of code included:

I could be wrong, but when I ran into this issue before, it was astroid using the environment of the extension (language server specifically, in this case) itself, instead of the user's workspace, so we prepend the proper virtual environment directory to the PATH to use that instead. If there's a better way, feel free to let me know!

a1-su · 2026-07-23T03:33:47Z

As a side note, I've essentially reverted the changes I made initially in the first PR (#8) since it was a proof of concept, and extension.ts doesn't need to be / shouldn't be changed from its original version for the LSP server implementation to work.

david-yz-liu

Hi @a1-su, I'll respond to your comment after testing this out locally.

I ran into an issue when running the extension: looks like an EOFError was raised.

I'm not sure what the best way to debug this is, but please first update the README with more detailed information on how you are starting and running the extension.

a1-su · 2026-07-26T06:45:26Z

Hi @a1-su, I'll respond to your comment after testing this out locally.

I ran into an issue when running the extension: looks like an EOFError was raised.

I'm not sure what the best way to debug this is, but please first update the README with more detailed information on how you are starting and running the extension.

As I was investigating the issue, I think I realized what the bug was and removed the code segment. If I had to guess, the EOFError you're encountering might be because we need to include some dependencies in bundled/lib as well, and I didn't include the proper instructions initially. In particular, we need to use a local version of PythonTA, since the latest release doesn't include the pyta-lsp option for the output format that we need for the extension. I've updated the README with the instructions as well.

The actual error was in the PythonTA repository. In the static_type_checker.py calls mypy directly, which uses the OS's PATH to determine which mypy executable this is.

https://github.com/pyta-uoft/pyta/blob/0e32f5244333e3cc3f27a2c1147aa93398bee8be/packages/python-ta/src/python_ta/checkers/static_type_checker.py#L91

call = ["mypy", filename] + mypy_options

However, if we use sys.executable, we can execute mypy using the selected Python interpreter. This isn't typically a problem with how PythonTA usually runs, but it means for the extension, we can have the language server run the proper mypy without explicitly updating the path with the Python interpreter.

call = [sys.executable, "-m", "mypy", filename] + mypy_options

I've made a PR on the PythonTA repository with this change, so if that change gets made and you install the local version with change, hopefully the extension will work properly 👍

david-yz-liu · 2026-07-26T18:22:43Z


 1. Install Python dependencies: `uv sync`.
 2. Install Javascript dependencies: `pnpm install`.
+3. Clone the [`pyta`](https://github.com/pyta-uoft/pyta) repository locally. The most recent release does not include the `pyta-lsp` output format needed for the VSCode extension.


This isn't necessary. Modify the pyproject.toml to specify the GitHub URL for installing PythonTA.

For the bundled/libs issue, I think you can modify step 1 above to replace the uv sync with a uv pip install --target bundled/libs -r pyproject.toml

david-yz-liu · 2026-07-26T18:23:38Z

+```

-To start the extension, use the `Debug Extension and Python` configuration in VS Code.
+To start the extension, use the `Debug Extension and Python` (shortcut `F5`) configuration in VS Code.


So overall I'm able to start the extension now and I don't think I see any errors, but I don't see anything happening, either. Please provide instructions in the README on what to do after the extension window opens. Add a video to the PR description as well.

david-yz-liu · 2026-07-26T18:24:08Z

        # 'path' setting takes priority over everything.
        use_path = True
        argv = settings["path"]
-    elif settings["interpreter"] and not utils.is_current_interpreter(


I see you deleted some of the code you added, but it also seems like we should then restore this block here.

david-yz-liu · 2026-07-26T18:53:21Z

@a1-su Claude helped identify an issue with the document URI filtering (Line 256 of lsp_server.py). There seems to be a path mismatch on Windows, and it suggest defining a normalization function:

def _normalize_uri_path(uri: str) -> str:
    """Normalizes a file URI to a comparable filesystem path.

    On Windows, `pathlib.Path.resolve()` uppercases drive letters (used by
    PythonTA's JSON reporter), while VS Code always sends `document.uri` with
    a lowercase drive letter. Comparing raw URI strings therefore never
    matches on Windows, so diagnostics must be compared as normalized paths.
    """
    return os.path.normcase(os.path.normpath(uris.to_fs_path(uri)))

Can you investigate this as well?

a1-su added 2 commits July 21, 2026 02:55

Implement PythonTA LSP

78b13bc

Update changelog

2dede84

a1-su force-pushed the implement-python-ta-lsp branch from b227c95 to 2dede84 Compare July 21, 2026 06:58

david-yz-liu reviewed Jul 21, 2026

View reviewed changes

a1-su added 2 commits July 22, 2026 23:24

Revert empty lines and use get_converter

5d8122b

Merge branch 'main' into implement-python-ta-lsp

a0c92d3

a1-su requested a review from david-yz-liu July 23, 2026 03:37

david-yz-liu reviewed Jul 23, 2026

View reviewed changes

Update README and remove unnecessary code

8b7f70c

david-yz-liu reviewed Jul 26, 2026

View reviewed changes

		return uris.to_fs_path(file_uri)
		return uris.to_fs_path(document.uri)

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a1-su commented Jul 21, 2026

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a1-su commented Jul 23, 2026

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a1-su commented Jul 26, 2026

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david-yz-liu commented Jul 26, 2026

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