build: adopt strict ty checks with prek

.pre-commit-config.yaml

@@ -11,14 +11,11 @@ repos:
         entry: .venv/bin/ruff format
         language: system
         types: [python]
-      - id: mypy
-        name: mypy
-        entry: .venv/bin/mypy
+      - id: ty
+        name: ty check
+        entry: .venv/bin/ty check
         language: system
         types: [python]
-        # parallel mypy processes share .mypy_cache, and mypy 2 can crash
-        # with an INTERNAL ERROR when they race on it
-        require_serial: true
       - id: shellcheck
         name: shellcheck
         entry: .venv/bin/shellcheck

AGENTS.md

@@ -14,7 +14,7 @@ Co-Authored-By: <agent and model> <email>
 - Set up: `uv sync`
 - Test: `uv run pytest tests/`
 - Test with coverage, as CI runs it: `uv run coverage erase && uv run coverage run -m pytest && uv run coverage report`
-- Lint, format, and type-check (ruff, mypy, shellcheck): `uv run prek run --all-files`
+- Lint, format, and type-check (ruff, ty, shellcheck): `uv run prek run --all-files`
 - Run your checkout against another repo: `uv run --project ~/code/devenv devenv sync` from that repo's root
 - Run the `bootstrap` workflow locally with `gh act`: `make test`
 

devenv/doctor.py

@@ -41,7 +41,7 @@ class Check:
     check: Callable[[], tuple[bool, str]]
     fix: Callable[[], tuple[bool, str]]
 
-    def __init__(self, module: ModuleType):
+    def __init__(self, module: ModuleType) -> None:
         # Check that the module has the required attributes.
         if not hasattr(module, "name"):
             raise ValueError("missing the `name` attribute")

devenv/lib/archive.py

@@ -10,6 +10,8 @@
 import urllib.request
 from collections.abc import Generator
 from collections.abc import Sequence
+from typing import BinaryIO
+from typing import cast
 from urllib.error import HTTPError
 
 from devenv.constants import home
@@ -59,9 +61,10 @@ def download(
     req = urllib.request.Request(url, headers=headers)
 
     retry_sleep = 1.0
+    resp: BinaryIO | None = None
     while retries >= 0:
         try:
-            resp = urllib.request.urlopen(req)
+            resp = cast(BinaryIO, urllib.request.urlopen(req))
             break
         except HTTPError as e:
             if retries == 0:
@@ -72,6 +75,7 @@ def download(
         retries -= 1
         retry_sleep *= retry_exp
 
+    assert resp is not None
     dest_dir = os.path.dirname(dest)
     os.makedirs(dest_dir, exist_ok=True)
 

devenv/lib/colima.py

@@ -10,6 +10,7 @@
 from collections.abc import Collection
 from dataclasses import dataclass
 from enum import Enum
+from typing import cast
 
 from devenv import constants
 from devenv.constants import SYSTEM_MACHINE
@@ -310,7 +311,7 @@ def _legacy_root_disk(config: colima_config.ColimaConfig) -> bool:
                 f"Colima store metadata {store_path} has an unsupported "
                 "format; inspect the existing VM before starting it."
             )
-        store = parsed
+        store = cast(dict[str, object], parsed)
 
     if store is not None:
         formatted = store.get("disk_formatted")

devenv/lib/colima_config.py

@@ -43,7 +43,11 @@ def _mapping(line: str, indent: int) -> tuple[str, str] | None:
     match = _MAPPING.match(_line_text(line))
     if match is None or len(match.group("indent")) != indent:
         return None
-    return match.group("key"), _commentless(match.group("rest"))
+    key = match.group("key")
+    value = match.group("rest")
+    if not isinstance(key, str) or not isinstance(value, str):
+        return None
+    return key, _commentless(value)
 
 
 def _quoted_key(line: str, indent: int) -> bool:
@@ -392,7 +396,7 @@ def set_snapshotter(path: str, snapshotter: bool) -> bool:
             "starting Colima."
         ) from error
 
-    temporary_path = ""
+    temporary_path: str | None = None
     try:
         descriptor, temporary_path = tempfile.mkstemp(
             prefix=".colima.yaml.", dir=os.path.dirname(path)
@@ -402,8 +406,9 @@ def set_snapshotter(path: str, snapshotter: bool) -> bool:
             file.write(replacement)
             file.flush()
             os.fsync(file.fileno())
+        assert temporary_path is not None
         os.replace(temporary_path, path)
-        temporary_path = ""
+        temporary_path = None
     except OSError as error:
         raise StorageMigrationBlocked(
             f"Unable to update Colima config {path}: {error}. The original "
@@ -412,7 +417,7 @@ def set_snapshotter(path: str, snapshotter: bool) -> bool:
             "starting Colima."
         ) from error
     finally:
-        if temporary_path:
+        if temporary_path is not None:
             try:
                 os.unlink(temporary_path)
             except FileNotFoundError:

devenv/lib/repository.py

@@ -1,8 +1,8 @@
 from __future__ import annotations
 
-import importlib
 import os.path
 from configparser import ConfigParser
+from importlib import metadata
 
 from devenv import constants
 from devenv.lib.config import get_config
@@ -34,7 +34,7 @@ def config(self) -> ConfigParser:
         return get_config(f"{self.config_path}/config.ini")
 
     def check_minimum_version(self) -> None:
-        version = importlib.metadata.version("sentry-devenv")
+        version = metadata.version("sentry-devenv")
 
         cfg = self.config()
         try:

devenv/lib/venv.py

@@ -57,7 +57,7 @@ def sync(
     editable_paths: Optional[tuple[str, ...]] = None,
     bins: Optional[tuple[str, ...]] = None,
 ) -> None:
-    cmd: tuple[str, ...] = (
+    cmd = [
         uv.find(),
         "pip",
         "install",
@@ -66,11 +66,11 @@ def sync(
         f"{venv_dir}/bin/python",
         "-r",
         requirements,
-    )
+    ]
     if editable_paths is not None:
         for path in editable_paths:
-            cmd = (*cmd, "-e", path)
-    proc.run(cmd)
+            cmd.extend(("-e", path))
+    proc.run(tuple(cmd))
 
     if bins is not None:
         binroot = fs.ensure_binroot(reporoot)

devenv/pin_gha.py

@@ -5,6 +5,7 @@
 import subprocess
 from collections.abc import Sequence
 from functools import lru_cache
+from typing import cast
 
 from devenv.lib.context import Context
 from devenv.lib.modules import DevModuleInfo
@@ -44,7 +45,7 @@ def main(context: Context, argv: Sequence[str] | None = None) -> int:
         "files", nargs="+", type=str, help="path to github actions file"
     )
     args = parser.parse_args(argv)
-    files: list[str] = args.files
+    files = cast(list[str], args.files)
 
     ACTION_VERSION_RE = re.compile(
         r"(?<=uses: )(?P<action>.*)@(?P<ref>[^#\s]+)"

pyproject.toml

@@ -35,6 +35,8 @@ line-length = 80
 
 [tool.ruff.lint]
 select = ["E", "F", "I"]
+extend-select = ["ANN", "PYI"]
+preview = true
 ignore = ["E501"]
 
 [tool.ruff.lint.isort]
@@ -48,53 +50,29 @@ skip-magic-trailing-comma = true
 [project.scripts]
 devenv = "devenv.main:main"
 
-[tool.mypy]
-python_version = "3.13"
-strict = true
-
-# disallow Any typing:
-disallow_any_unimported = true
-# there's too many Any's in typeshed:
-disallow_any_expr = false
-disallow_any_decorated = true
-disallow_any_explicit = true
-
-implicit_reexport = false
-
-warn_no_return = true
-warn_unreachable = true
-
-allow_redefinition = true
-
-[tool.pyright]
-include = ["."]
-pythonVersion = "3.13"
-
-typeCheckingMode = "strict"
-
-# turn on all the checks not already enabled by "strict":
-reportCallInDefaultInitializer = "error"
-reportImplicitStringConcatenation = "error"
-reportMissingSuperCall = "error"
-reportPropertyTypeMismatch = "error"
-reportUninitializedInstanceVariable = "error"
-reportUnnecessaryTypeIgnoreComment = "error"
-reportUnusedCallResult = "none"  # too noisy
-
-# don't flag arguments as long as their type is known
-reportMissingParameterType = "none"
-reportUnknownParameterType = "error"
-#### don't flag missing typestubs, as long as everything is typed
-###reportMissingTypeStubs = false
+[tool.ty.analysis]
+strict-equality-semantics = true
+strict-generic-narrowing = true
+
+[tool.ty.rules]
+dynamic-function-decorator-return = "error"
+missing-type-argument = "error"
+possibly-unresolved-reference = "warn"
+unsound-assignment = "error"
+unsound-return-statement = "error"
+unsound-yield = "error"
+unsupported-dynamic-base = "warn"
+possibly-missing-attribute = "warn"
+possibly-missing-import = "warn"
 
 [dependency-groups]
 dev = [
   "coverage",
   "covdefaults",
-  "mypy",
   "prek",
   "pytest",
   "re-assert",
   "ruff",
   "shellcheck-py",
+  "ty",
 ]

tests/lib/test_archive.py

@@ -6,7 +6,9 @@
 import tarfile
 import time
 import typing
+import urllib.error
 import urllib.request
+from http.client import HTTPMessage
 from unittest import mock
 
 import pytest
@@ -150,12 +152,16 @@ def tar5(tmp_path: pathlib.Path) -> pathlib.Path:
 
 
 @pytest.fixture
-def mock_sleep() -> typing.Generator[mock.MagicMock, None, None]:
+def mock_sleep() -> typing.Generator[
+    mock.MagicMock | mock.AsyncMock, None, None
+]:
     with mock.patch.object(time, "sleep", autospec=True) as mock_sleep:
         yield mock_sleep
 
 
-def test_download(tmp_path: pathlib.Path, mock_sleep: mock.MagicMock) -> None:
+def test_download(
+    tmp_path: pathlib.Path, mock_sleep: mock.MagicMock | mock.AsyncMock
+) -> None:
     data = b"foo\n"
     data_sha256 = (
         "b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c"
@@ -165,7 +171,7 @@ def test_download(tmp_path: pathlib.Path, mock_sleep: mock.MagicMock) -> None:
         "https://example.com/foo",
         503,
         "Service Unavailable",
-        "",  # type: ignore
+        HTTPMessage(),
         io.BytesIO(b""),
     )
 
@@ -195,7 +201,7 @@ def test_download(tmp_path: pathlib.Path, mock_sleep: mock.MagicMock) -> None:
 
 
 def test_download_exceeded_retries(
-    tmp_path: pathlib.Path, mock_sleep: mock.MagicMock
+    tmp_path: pathlib.Path, mock_sleep: mock.MagicMock | mock.AsyncMock
 ) -> None:
     data_sha256 = (
         "b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c"
@@ -205,7 +211,7 @@ def test_download_exceeded_retries(
         "https://example.com/foo",
         503,
         "Service Unavailable",
-        "",  # type: ignore
+        HTTPMessage(),
         io.BytesIO(b""),
     )
     dest = f"{tmp_path}/a"
@@ -226,7 +232,7 @@ def test_download_exceeded_retries(
 
 
 def test_download_dest_is_broken_symlink(
-    tmp_path: pathlib.Path, mock_sleep: mock.MagicMock
+    tmp_path: pathlib.Path, mock_sleep: mock.MagicMock | mock.AsyncMock
 ) -> None:
     data = b"foo\n"
     data_sha256 = (
@@ -251,7 +257,7 @@ def test_download_dest_is_broken_symlink(
 
 
 def test_download_wrong_sha(
-    tmp_path: pathlib.Path, mock_sleep: mock.MagicMock
+    tmp_path: pathlib.Path, mock_sleep: mock.MagicMock | mock.AsyncMock
 ) -> None:
     data = b"foo\n"
     data_sha256 = (

tests/lib/test_colima_storage.py

@@ -314,7 +314,7 @@ def test_stopped_legacy_vm_ignores_standalone_lima_disk(tmp_path: Path) -> None:
     limactl = root / "bin/limactl"
     limactl.parent.mkdir(parents=True)
     limactl.touch()
-    probe_environments: list[dict[str, str] | None] = []
+    probe_environments: list[object | None] = []
 
     def run(command: tuple[str, ...], **kwargs: object) -> str:
         if command[0].endswith("limactl"):
@@ -352,7 +352,7 @@ def test_stopped_modern_vm_disk_prevents_overlay2_override(
     limactl = root / "bin/limactl"
     limactl.parent.mkdir(parents=True)
     limactl.touch()
-    probe_environments: list[dict[str, str] | None] = []
+    probe_environments: list[object | None] = []
 
     def run(command: tuple[str, ...], **kwargs: object) -> str:
         if command[0].endswith("limactl"):
@@ -394,7 +394,7 @@ def test_explicit_lima_home_is_used_for_colima_instance_and_disk_probe(
     limactl = root / "bin/limactl"
     limactl.parent.mkdir(parents=True)
     limactl.touch()
-    probe_environments: list[dict[str, str] | None] = []
+    probe_environments: list[object | None] = []
 
     def run(command: tuple[str, ...], **kwargs: object) -> str:
         if command[0].endswith("limactl"):