LSP Types

Publish the excellent work of Sublime LSP as a PyPI package.

LSP Types is a Python package that aims to provide a fully typed interface to Language Server Protocol (LSP) interactions. It can be used to simply utilize the types, or to interact with an LSP server over stdio.

The library has minimal dependencies (tomli-w for TOML config serialization).

Installation

pip install lsp-types

Usage

Using the LSP types:

import lsp_types

# Use the types

Using an LSP process through stdio:

Tip

Recommend using basedpyright for extended features.

from lsp_types.process import LSPProcess, ProcessLaunchInfo

process_info = ProcessLaunchInfo(cmd=[
    "pyright-langserver", "--stdio"
])

async with LSPProcess(process_info) as process:
    # Initialize the process
    ...

    # Grab a typed listener
    diagnostics_listener = process.notify.on_publish_diagnostics(timeout=1.0)

    # Send a notification (`await` is optional. It ensures messages have been drained)
    await process.notify.did_open_text_document(...)

    # Wait for diagnostics to come in
    diagnostics = await diagnostics_listener

LSPs

The following LSPs are available out of the box:

• Pyright
• Pyrefly
• ty - Astral's fast Python type checker

Feature Support Matrix

Legend

Symbol	Meaning
✅	Fully supported
⚠️	Partial support (see notes)
❌	Not supported
❔	Not tested / Not exposed in API

Features by Backend

Last verified: basedpyright 1.36.2, Pyrefly 0.48.2, ty 0.0.12

Feature	Pyright	Pyrefly	ty	Notes
Diagnostics	✅	✅	⚠️	ty requires files on disk
Hover	✅	✅	✅	ty shows type only, not variable name
Completion	✅	✅	⚠️	ty requires files on disk
Completion Resolution	✅	❌	✅	Pyrefly: not yet supported
Signature Help	✅	✅	✅
Rename	✅	⚠️	⚠️	Pyrefly: disabled for external files; ty: requires files on disk
Semantic Tokens	✅*	✅	✅	*basedpyright recommended for extended features
Go to Definition	❔	❔	❔	Not exposed in Session API
Find References	❔	❔	❔	Not exposed in Session API
Code Actions	❔	❔	❔	Not exposed in Session API
Formatting	❔	❔	❔	Not exposed in Session API

See Feature Verification Guide for methodology on maintaining this table.

For detailed backend limitations:

• Pyrefly Known Limitations
• ty Known Limitations

Pyright Example

from lsp_types import Session
from lsp_types.pyright.backend import PyrightBackend

async def test_pyright_session():
    code = """\
def greet(name: str) -> str:
    return 123
"""

    session = await Session.create(PyrightBackend(), initial_code=code)
    diagnostics = await session.get_diagnostics()

    assert diagnostics != []

    code = """\
def greet(name: str) -> str:
    return f"Hello, {name}"
"""

    await session.update_code(code)
    diagnostics = await session.get_diagnostics()
    assert diagnostics == []

    await session.shutdown()

Development

• Requires Python 3.12+.
• Requires uv for dev dependencies.

Generate latest types in one go:

make generate-latest-types

Download the latest json schema:

make download-schemas

Generate the types:

make generate-types

Copy the lsp_types/types.py file to your project.

NOTE: Do not import types that begin with __. These types are internal types and are not meant to be used.

TODOs

• Support server request handlers.