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:

importlsp_types# Use the types

Using an LSP process through stdio:

Tip

Recommend using basedpyright for extended features.

fromlsp_types.processimportLSPProcess, ProcessLaunchInfoprocess_info=ProcessLaunchInfo(cmd=[
"pyright-langserver", "--stdio"
])
asyncwithLSPProcess(process_info) asprocess:
# Initialize the process
...
# Grab a typed listenerdiagnostics_listener=process.notify.on_publish_diagnostics(timeout=1.0)
# Send a notification (`await` is optional. It ensures messages have been drained)awaitprocess.notify.did_open_text_document(...)
# Wait for diagnostics to come indiagnostics=awaitdiagnostics_listener

LSPProcess.stop() is terminal — including the implicit stop() when the async with block exits. Calling start() on a stopped process raises RuntimeError instead of relaunching the server, and requests and notifications sent through it raise RuntimeError too (notifications are no longer dropped with a warning). The messages name the state they came from (LSP process has been stopped vs. LSP process has not been started). Construct a new LSPProcess when you need to restart a server.

LSPs

The following LSPs are available out of the box:

• Pyright
• Pyrefly
• ty - Astral's fast Python type checker
• Zuban - Rust-based type checker + LSP by the author of Jedi

Pyrefly CLI tools

This library drives Pyrefly's LSP server (pyrefly lsp), but Pyrefly also ships a broader standalone CLI worth knowing about (verified with Pyrefly 1.2.0):

Command	What it does
pyrefly init	Scaffold a pyrefly.toml (or [tool.pyrefly] in pyproject.toml), or migrate an existing mypy/pyright config to Pyrefly
pyrefly check	Full type check of a file or project
pyrefly snippet <CODE>	Type-check an inline code snippet
pyrefly infer	Automatically add inferred type annotations to a file or directory
pyrefly coverage	Type-coverage reporting commands
pyrefly suppress	Add ignore comments for existing errors, or remove unused ignores
pyrefly stubgen	Generate .pyi stub files from Python source
pyrefly dump-config	Print Pyrefly's resolved configuration
pyrefly tsp	Start a TSP (Type Server Protocol) server (new in 1.2.x)

Run pyrefly <command> --help for details, or see the Pyrefly docs.

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 1.39.9, Pyrefly 1.2.0, ty 0.0.61, Zuban 0.9.0

Feature	Pyright	Pyrefly	ty	Zuban	Notes
Diagnostics	✅	✅	⚠️	✅	ty requires files on disk
Hover	✅	✅	✅	✅	ty shows type only, not variable name
Completion	✅	✅	⚠️	✅	ty requires files on disk
Completion Resolution	✅	❌	❌	✅	Pyrefly: no-op (returns item unchanged); ty: not supported (-32601)
Signature Help	✅	✅	✅	✅
Rename	✅	✅	⚠️	✅	ty: requires files on disk
Semantic Tokens	✅*	✅**	✅	✅	*basedpyright recommended; **Pyrefly: legend not advertised (see docs)
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 documentation:

• Semantic Tokens Reference - Token types and modifiers for Monaco/editor integration
• Pyrefly Known Limitations
• ty Known Limitations
• Zuban Known Limitations

Pyright Example

fromlsp_typesimportSessionfromlsp_types.pyright.backendimportPyrightBackendasyncdeftest_pyright_session():
code="""\def greet(name: str) -> str: return 123"""session=awaitSession.create(PyrightBackend(), initial_code=code)
diagnostics=awaitsession.get_diagnostics()
assertdiagnostics!= []
code="""\def greet(name: str) -> str: return f"Hello, {name}""""awaitsession.update_code(code)
diagnostics=awaitsession.get_diagnostics()
assertdiagnostics== []
awaitsession.shutdown()

After shutdown(), a session's operational methods raise RuntimeError; its captured server and semantic-token metadata remain readable. Calling shutdown() while other operations are in flight is safe: it waits up to five seconds for them to finish, and if any are still running it stops the language server process instead of returning it to the pool, keeping stale operations out of the next session's protocol stream. (One narrow exception: cancelling an operation ends its in-flight accounting even if a notification write it already queued is still being flushed.)

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.