Add TypeAlias annotations for improved type clarity

Leverage TypeAlias (available in Python 3.10+) to explicitly mark
type aliases throughout the codebase:

- _hooks.py: _Namespace, _Plugin, _HookExec, _HookImplFunction, _CallHistory
- _manager.py: _BeforeTrace, _AfterTrace
- _result.py: _ExcInfo
- _callers.py: Teardown

This improves IDE support, type checker accuracy, and makes the
distinction between type aliases and regular assignments clear.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: RonnyPfannschmidt

src/pluggy/_callers.py

@@ -9,6 +9,7 @@
 from collections.abc import Sequence
 from typing import cast
 from typing import NoReturn
+from typing import TypeAlias
 import warnings
 
 from ._hooks import HookImpl
@@ -19,7 +20,7 @@
 
 # Need to distinguish between old- and new-style hook wrappers.
 # Wrapping with a tuple is the fastest type-safe way I found to do it.
-Teardown = Generator[None, object, object]
+Teardown: TypeAlias = Generator[None, object, object]
 
 
 def run_old_style_hookwrapper(

src/pluggy/_hooks.py

@@ -17,6 +17,7 @@
 from typing import final
 from typing import overload
 from typing import TYPE_CHECKING
+from typing import TypeAlias
 from typing import TypedDict
 from typing import TypeVar
 import warnings
@@ -26,13 +27,14 @@
 
 _T = TypeVar("_T")
 _F = TypeVar("_F", bound=Callable[..., object])
-_Namespace = ModuleType | type
-_Plugin = object
-_HookExec = Callable[
+
+_Namespace: TypeAlias = ModuleType | type
+_Plugin: TypeAlias = object
+_HookExec: TypeAlias = Callable[
     [str, Sequence["HookImpl"], Mapping[str, object], bool],
     object | list[object],
 ]
-_HookImplFunction = Callable[..., _T | Generator[None, Result[_T], None]]
+_HookImplFunction: TypeAlias = Callable[..., _T | Generator[None, Result[_T], None]]
 
 
 class HookspecOpts(TypedDict):
@@ -372,7 +374,9 @@ def __getattr__(self, name: str) -> HookCaller: ...
 _HookRelay = HookRelay
 
 
-_CallHistory = list[tuple[Mapping[str, object], Callable[[Any], None] | None]]
+_CallHistory: TypeAlias = list[
+    tuple[Mapping[str, object], Callable[[Any], None] | None]
+]
 
 
 class HookCaller:

src/pluggy/_manager.py

@@ -10,6 +10,7 @@
 from typing import cast
 from typing import Final
 from typing import TYPE_CHECKING
+from typing import TypeAlias
 import warnings
 
 from . import _tracing
@@ -32,8 +33,10 @@
     import importlib.metadata
 
 
-_BeforeTrace = Callable[[str, Sequence[HookImpl], Mapping[str, Any]], None]
-_AfterTrace = Callable[[Result[Any], str, Sequence[HookImpl], Mapping[str, Any]], None]
+_BeforeTrace: TypeAlias = Callable[[str, Sequence[HookImpl], Mapping[str, Any]], None]
+_AfterTrace: TypeAlias = Callable[
+    [Result[Any], str, Sequence[HookImpl], Mapping[str, Any]], None
+]
 
 
 def _warn_for_function(warning: Warning, function: Callable[..., object]) -> None:

src/pluggy/_result.py

@@ -9,10 +9,11 @@
 from typing import cast
 from typing import final
 from typing import Generic
+from typing import TypeAlias
 from typing import TypeVar
 
 
-_ExcInfo = tuple[type[BaseException], BaseException, TracebackType | None]
+_ExcInfo: TypeAlias = tuple[type[BaseException], BaseException, TracebackType | None]
 ResultType = TypeVar("ResultType")