refactor: replace mypy with ty for static type checking

AGENTS.md

@@ -15,7 +15,7 @@ Follow these instructions in addition to any higher-level system or tool rules.
   - `commitizen/commands/` - subcommands such as `bump`, `commit`, `changelog`, `check`, etc.
   - `commitizen/config/` - configuration discovery and loading.
   - `commitizen/providers/` - version providers (e.g., `pep621`, `poetry`, `npm`, `uv`).
-- **Config sources**: `pyproject.toml` (project config, poe tasks, ruff, mypy), `.pre-commit-config.yaml` (hooks), `.github/workflows/` (CI).
+- **Config sources**: `pyproject.toml` (project config, poe tasks, ruff, ty), `.pre-commit-config.yaml` (hooks), `.github/workflows/` (CI).
 
 ## General Expectations
 
@@ -34,7 +34,7 @@ uv sync --frozen --group base --group test --group linters
 ### Local commands
 
 - **Format**: `uv run poe format` (runs `ruff check --fix` then `ruff format`)
-- **Lint**: `uv run poe lint` (runs `ruff check` then `mypy`)
+- **Lint**: `uv run poe lint` (runs `ruff check` then `ty check`)
 - **Test**: `uv run poe test` (runs `pytest -n auto`)
 - **CI-equivalent**: `uv run poe ci` (commit check + pre-commit hooks via `prek` + test with coverage)
 - **Full local check**: `uv run poe all` (format + lint + check-commit + coverage)
@@ -50,7 +50,7 @@ Always run at least `uv run ruff check --fix . && uv run ruff format .` before p
 ### Common CI failure patterns
 
 - **"Format Python code...Failed"**: Run `uv run poe format` and commit the result.
-- **mypy `[arg-type]` on TypedDict**: Dynamically-constructed dicts (e.g., from `pytest.mark.parametrize`) passed to TypedDict-typed params need `# type: ignore[arg-type]`.
+- **ty `invalid-argument-type` on TypedDict**: Dynamically-constructed dicts (e.g., from `pytest.mark.parametrize`) passed to TypedDict-typed params need `# type: ignore  # noqa: PGH003` or `cast()`.
 - **"pathspec 'vX.Y.Z' did not match"**: `.pre-commit-config.yaml` pins a tag of this repo. Rebase onto master to pick up the tag.
 - **`VersionProtocol` + `issubclass`**: This Protocol has non-method members (properties), so `issubclass()` raises `TypeError`. Use `hasattr` checks for runtime validation.
 

commitizen/changelog.py

@@ -32,7 +32,7 @@
 from dataclasses import dataclass
 from datetime import date
 from itertools import chain
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, cast
 
 from deprecated import deprecated
 from jinja2 import (
@@ -192,10 +192,14 @@ def process_commit_message(
 
     messages = [processed_msg] if isinstance(processed_msg, dict) else processed_msg
     for msg in messages:
-        change_type = msg.pop("change_type", None)
+        if not isinstance(msg, dict):
+            continue
+        # cast needed: ty cannot narrow dict type from Iterable union
+        msg_dict = cast("dict[str, Any]", msg)
+        change_type = msg_dict.pop("change_type", None)
         if change_type_map and change_type:
             change_type = change_type_map.get(change_type, change_type)
-        ref_changes[change_type].append(msg)
+        ref_changes[change_type].append(msg_dict)
 
 
 def generate_ordered_changelog_tree(
@@ -272,6 +276,7 @@ def incremental_build(
             skip = False
             if (
                 latest_version_position is None
+                or unreleased_end is None
                 or latest_version_position > unreleased_end
             ):
                 continue

commitizen/changelog_formats/__init__.py

@@ -70,14 +70,16 @@ def get_changelog_format(
     :raises FormatUnknown: if a non-empty name is provided but cannot be found in the known formats
     """
     name: str | None = config.settings.get("changelog_format")
-    format = (
-        name and KNOWN_CHANGELOG_FORMATS.get(name) or _guess_changelog_format(filename)
+    format_cls: type[ChangelogFormat] | None = (
+        KNOWN_CHANGELOG_FORMATS.get(name) if name else None
     )
+    if format_cls is None:
+        format_cls = _guess_changelog_format(filename)
 
-    if not format:
+    if not format_cls:
         raise ChangelogFormatUnknown(f"Unknown changelog format '{name}'")
 
-    return format(config)
+    return format_cls(config)
 
 
 def _guess_changelog_format(filename: str | None) -> type[ChangelogFormat] | None:

commitizen/cli.py

@@ -720,7 +720,7 @@ def main() -> None:
     if args.no_raise:
         sys.excepthook = partial(sys.excepthook, no_raise=parse_no_raise(args.no_raise))
 
-    args.func(conf, arguments)()  # type: ignore[arg-type]
+    args.func(conf, arguments)()  # type: ignore  # noqa: PGH003
 
 
 if __name__ == "__main__":

commitizen/commands/bump.py

@@ -8,7 +8,7 @@
 
 from commitizen import bump, factory, git, hooks, out
 from commitizen.changelog_formats import get_changelog_format
-from commitizen.commands.changelog import Changelog
+from commitizen.commands.changelog import Changelog, ChangelogArgs
 from commitizen.defaults import Settings
 from commitizen.exceptions import (
     BumpCommitFailedError,
@@ -263,7 +263,7 @@ def __call__(self) -> None:
             )
         )
 
-        rules = TagRules.from_settings(cast("Settings", self.bump_settings))
+        rules = TagRules.from_settings(self.bump_settings)
         current_tag = rules.find_tag_for(git.get_tags(), current_version)
         current_tag_version = (
             current_tag.name if current_tag else rules.normalize_tag(current_version)
@@ -323,18 +323,22 @@ def __call__(self) -> None:
                 try:
                     Changelog(
                         self.config,
-                        {**changelog_args, "dry_run": True},  # type: ignore[typeddict-item]
+                        {**changelog_args, "dry_run": True},
                     )()
                 except DryRunExit:
                     pass
 
             changelog_cmd = Changelog(
                 self.config,
-                {
-                    **changelog_args,  # type: ignore[typeddict-item]
-                    "file_name": self.file_name,
-                    "allow_no_commit": bool(self.arguments["allow_no_commit"]),
-                },
+                # TODO: remove cast once self.file_name is narrowed to str
+                cast(
+                    "ChangelogArgs",
+                    {
+                        **changelog_args,
+                        "file_name": self.file_name,
+                        "allow_no_commit": bool(self.arguments["allow_no_commit"]),
+                    },
+                ),
             )
             changelog_cmd()
             changelog_file_name = changelog_cmd.file_name

commitizen/commands/changelog.py

@@ -3,7 +3,7 @@
 from difflib import SequenceMatcher
 from operator import itemgetter
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, TypedDict, cast
+from typing import TYPE_CHECKING, Any, TypedDict
 
 from commitizen import changelog, defaults, factory, git, out
 from commitizen.changelog_formats import get_changelog_format
@@ -99,11 +99,10 @@ def __init__(self, config: BaseConfig, arguments: ChangelogArgs) -> None:
         self.change_type_map = (
             self.config.settings.get("change_type_map") or self.cz.change_type_map
         )
-        self.change_type_order = cast(
-            "list[str]",
+        self.change_type_order: list[str] = (
             self.config.settings.get("change_type_order")
             or self.cz.change_type_order
-            or defaults.CHANGE_TYPE_ORDER,
+            or defaults.CHANGE_TYPE_ORDER
         )
         self.rev_range = arguments.get("rev_range")
         self.tag_rules = TagRules(

commitizen/config/__init__.py

@@ -31,7 +31,7 @@ def _create_config_from_path(path: Path) -> BaseConfig:
     return create_config(data=path.read_bytes(), path=path)
 
 
-def read_cfg(filepath: str | None = None) -> BaseConfig:
+def read_cfg(filepath: str | Path | None = None) -> BaseConfig:
     if filepath is not None:
         conf_path = Path(filepath)
         if not conf_path.is_file():

commitizen/config/base_config.py

@@ -33,7 +33,7 @@ def settings(self) -> Settings:
 
     @property
     def path(self) -> Path:
-        return self._path  # type: ignore[return-value]
+        return self._path  # type: ignore  # noqa: PGH003
 
     @path.setter
     def path(self, path: Path) -> None:

commitizen/config/toml_config.py

@@ -36,7 +36,7 @@ def init_empty_config_content(self) -> None:
 
         if config_doc.get("tool") is None:
             config_doc["tool"] = table()
-        config_doc["tool"]["commitizen"] = table()  # type: ignore[index]
+        config_doc["tool"]["commitizen"] = table()  # type: ignore  # noqa: PGH003
 
         with self.path.open("wb") as output_toml_file:
             output_toml_file.write(
@@ -46,7 +46,7 @@ def init_empty_config_content(self) -> None:
     def set_key(self, key: str, value: object) -> Self:
         config_doc = parse(self.path.read_bytes())
 
-        config_doc["tool"]["commitizen"][key] = value  # type: ignore[index]
+        config_doc["tool"]["commitizen"][key] = value  # type: ignore  # noqa: PGH003
         self.path.write_bytes(config_doc.as_string().encode(self._settings["encoding"]))
 
         return self
@@ -65,6 +65,6 @@ def _parse_setting(self, data: bytes | str) -> None:
             raise InvalidConfigurationError(f"Failed to parse {self.path}: {e}")
 
         try:
-            self.settings.update(doc["tool"]["commitizen"])  # type: ignore[index,typeddict-item] # TODO: fix this
+            self.settings.update(doc["tool"]["commitizen"])  # type: ignore  # noqa: PGH003  # TODO: fix this
         except exceptions.NonExistentKey:
             pass

commitizen/cz/conventional_commits/conventional_commits.py

@@ -150,7 +150,7 @@ def questions(self) -> list[CzQuestion]:
             },
         ]
 
-    def message(self, answers: ConventionalCommitsAnswers) -> str:  # type: ignore[override]
+    def message(self, answers: ConventionalCommitsAnswers) -> str:  # type: ignore  # noqa: PGH003
         prefix = answers["prefix"]
         scope = answers["scope"]
         subject = answers["subject"]

commitizen/cz/customize/customize.py

@@ -50,12 +50,14 @@ def __init__(self, config: BaseConfig) -> None:
                 setattr(self, attr_name, value)
 
     def questions(self) -> list[CzQuestion]:
-        return self.custom_settings.get("questions", [{}])  # type: ignore[return-value]
+        return self.custom_settings.get("questions", [{}])  # type: ignore  # noqa: PGH003
 
     def message(self, answers: Mapping[str, Any]) -> str:
         message_template = Template(self.custom_settings.get("message_template", ""))
         if getattr(Template, "substitute", None):
-            return message_template.substitute(**answers)  # type: ignore[attr-defined,no-any-return] # pragma: no cover # TODO: check if we can fix this
+            return message_template.substitute(  # type: ignore[attr-defined]
+                **answers
+            )  # pragma: no cover # TODO: check if we can fix this
         return message_template.render(**answers)
 
     def example(self) -> str:

commitizen/git.py

@@ -5,6 +5,7 @@
 from functools import lru_cache
 from pathlib import Path
 from tempfile import NamedTemporaryFile
+from typing import IO, Any
 
 from commitizen import cmd, out
 from commitizen.exceptions import GitCommandError
@@ -316,7 +317,7 @@ def get_core_editor() -> str | None:
     return None
 
 
-def smart_open(*args, **kwargs):  # type: ignore[no-untyped-def,unused-ignore] # noqa: ANN201
+def smart_open(*args: Any, **kwargs: Any) -> IO[Any]:
     """Open a file with the EOL style determined from Git."""
     return open(*args, newline=EOLType.for_open(), **kwargs)
 

commitizen/providers/base_provider.py

@@ -94,7 +94,7 @@ def set_version(self, version: str) -> None:
         self.file.write_text(tomlkit.dumps(document), encoding=self._get_encoding())
 
     def get(self, document: tomlkit.TOMLDocument) -> str:
-        return document["project"]["version"]  # type: ignore[index,return-value]
+        return document["project"]["version"]  # type: ignore  # noqa: PGH003
 
     def set(self, document: tomlkit.TOMLDocument, version: str) -> None:
-        document["project"]["version"] = version  # type: ignore[index]
+        document["project"]["version"] = version  # type: ignore  # noqa: PGH003

commitizen/providers/cargo_provider.py

@@ -53,12 +53,12 @@ def set_lock_version(self, version: str) -> None:
             assert isinstance(packages, AoT)
 
         try:
-            cargo_package_name = cargo_toml_content["package"]["name"]  # type: ignore[index]
+            cargo_package_name = cargo_toml_content["package"]["name"]  # type: ignore  # noqa: PGH003
             if TYPE_CHECKING:
                 assert isinstance(cargo_package_name, str)
             for i, package in enumerate(packages):
                 if package["name"] == cargo_package_name:
-                    cargo_lock_content["package"][i]["version"] = version  # type: ignore[index]
+                    cargo_lock_content["package"][i]["version"] = version  # type: ignore  # noqa: PGH003
                     break
         except NonExistentKey:
             workspace = cargo_toml_content.get("workspace", {})
@@ -94,7 +94,7 @@ def set_lock_version(self, version: str) -> None:
 
             for i, package in enumerate(packages):
                 if package["name"] in members_inheriting:
-                    cargo_lock_content["package"][i]["version"] = version  # type: ignore[index]
+                    cargo_lock_content["package"][i]["version"] = version  # type: ignore  # noqa: PGH003
 
         self.lock_file.write_text(
             dumps(cargo_lock_content), encoding=self._get_encoding()

commitizen/providers/poetry_provider.py

@@ -15,8 +15,8 @@ class PoetryProvider(TomlProvider):
 
     filename = "pyproject.toml"
 
-    def get(self, pyproject: tomlkit.TOMLDocument) -> str:
-        return pyproject["tool"]["poetry"]["version"]  # type: ignore[index,return-value]
+    def get(self, document: tomlkit.TOMLDocument) -> str:
+        return document["tool"]["poetry"]["version"]  # type: ignore  # noqa: PGH003
 
-    def set(self, pyproject: tomlkit.TOMLDocument, version: str) -> None:
-        pyproject["tool"]["poetry"]["version"] = version  # type: ignore[index]
+    def set(self, document: tomlkit.TOMLDocument, version: str) -> None:
+        document["tool"]["poetry"]["version"] = version  # type: ignore  # noqa: PGH003

commitizen/providers/uv_provider.py

@@ -29,17 +29,17 @@ def set_lock_version(self, version: str) -> None:
         pyproject_toml_content = tomlkit.parse(
             self.file.read_text(encoding=self._get_encoding())
         )
-        project_name = pyproject_toml_content["project"]["name"]  # type: ignore[index]
+        project_name = pyproject_toml_content["project"]["name"]  # type: ignore  # noqa: PGH003
         normalized_project_name = canonicalize_name(str(project_name))
 
         document = tomlkit.parse(
             self.lock_file.read_text(encoding=self._get_encoding())
         )
 
-        packages: tomlkit.items.AoT = document["package"]  # type: ignore[assignment]
+        packages: tomlkit.items.AoT = document["package"]  # type: ignore  # noqa: PGH003
         for i, package in enumerate(packages):
             if package["name"] == normalized_project_name:
-                document["package"][i]["version"] = version  # type: ignore[index]
+                document["package"][i]["version"] = version  # type: ignore  # noqa: PGH003
                 break
         self.lock_file.write_text(
             tomlkit.dumps(document), encoding=self._get_encoding()

commitizen/version_schemes.py

@@ -159,7 +159,7 @@ def scheme(self) -> VersionScheme:
 
     @property
     def prerelease(self) -> str | None:
-        # version.pre is needed for mypy check
+        # version.pre is needed for static type checking
         if self.is_prerelease and self.pre:
             return f"{self.pre[0]}{self.pre[1]}"
         return None
@@ -253,7 +253,7 @@ def bump(
 
         if self.local and is_local_version:
             local_version = self.scheme(self.local).bump(increment)
-            return self.scheme(f"{self.public}+{local_version}")  # type: ignore[return-value]
+            return self.scheme(f"{self.public}+{local_version}")  # type: ignore  # noqa: PGH003
 
         base = self._get_increment_base(increment, exact_increment)
         dev_version = self.generate_devrelease(devrelease)
@@ -270,7 +270,7 @@ def bump(
         # TODO: post version
         return self.scheme(
             f"{base}{pre_version}{dev_version}{self.generate_build_metadata(build_metadata)}"
-        )  # type: ignore[return-value]
+        )  # type: ignore  # noqa: PGH003
 
     def _get_increment_base(
         self, increment: Increment | None, exact_increment: bool
@@ -385,7 +385,8 @@ def _get_prerelease(self) -> str:
         return ".".join(prerelease_parts)
 
 
-DEFAULT_SCHEME: VersionScheme = Pep440
+# cast needed: ty cannot resolve type[Pep440] as type[VersionProtocol]
+DEFAULT_SCHEME: VersionScheme = cast("VersionScheme", Pep440)
 
 SCHEMES_ENTRYPOINT = "commitizen.scheme"
 """Schemes entrypoints group"""
@@ -420,7 +421,7 @@ def get_version_scheme(settings: Settings, name: str | None = None) -> VersionSc
         (ep,) = metadata.entry_points(name=name, group=SCHEMES_ENTRYPOINT)
     except ValueError:
         raise VersionSchemeUnknown(f'Version scheme "{name}" unknown.')
-    scheme = cast("VersionScheme", ep.load())
+    scheme: VersionScheme = ep.load()
 
     # `VersionProtocol` is a `@runtime_checkable` Protocol, but `issubclass()` is not
     # supported for Protocols with non-method members. We check an instance instead by

docs/contributing/contributing_tldr.md

@@ -20,11 +20,11 @@ uv sync --dev --frozen
 # Make ruff happy
 uv run poe format
 
-# Check if ruff and mypy are happy
+# Check if ruff and ty are happy
 uv run poe lint
 
-# Check if mypy is happy in python 3.10
-mypy --python-version 3.10
+# Check ty against Python 3.10 types (matches [tool.ty.environment] python-version)
+uv run ty check --python-version 3.10
 
 # Run tests in parallel.
 pytest -n auto # This may take a while.