diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index ac0ff69..9c01fc4 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -10,6 +10,7 @@ on:
     # required if branches-ignore is supplied (jaraco/skeleton#103)
     - '**'
   pull_request:
+  workflow_dispatch:
 
 permissions:
   contents: read
@@ -34,23 +35,25 @@ jobs:
       # https://blog.jaraco.com/efficient-use-of-ci-resources/
       matrix:
         python:
-        - "3.8"
-        - "3.12"
+        - "3.9"
+        - "3.13"
         platform:
         - ubuntu-latest
         - macos-latest
         - windows-latest
         include:
-        - python: "3.9"
-          platform: ubuntu-latest
         - python: "3.10"
           platform: ubuntu-latest
         - python: "3.11"
           platform: ubuntu-latest
+        - python: "3.12"
+          platform: ubuntu-latest
+        - python: "3.14"
+          platform: ubuntu-latest
         - python: pypy3.10
           platform: ubuntu-latest
     runs-on: ${{ matrix.platform }}
-    continue-on-error: ${{ matrix.python == '3.13' }}
+    continue-on-error: ${{ matrix.python == '3.14' }}
     steps:
       - uses: actions/checkout@v4
       - name: Setup Python
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 8ec58e2..04870d1 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,6 +1,6 @@
 repos:
 - repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.5.6
+  rev: v0.7.1
   hooks:
   - id: ruff
     args: [--fix, --unsafe-fixes]
diff --git a/NEWS.rst b/NEWS.rst
index 36aac37..c3612c1 100644
--- a/NEWS.rst
+++ b/NEWS.rst
@@ -1,3 +1,13 @@
+v6.5.0
+======
+
+Features
+--------
+
+- Add type annotations for Traversable.open. (#317)
+- Require Python 3.9 or later.
+
+
 v6.4.5
 ======
 
diff --git a/README.rst b/README.rst
index b302f62..4f9fa02 100644
--- a/README.rst
+++ b/README.rst
@@ -14,7 +14,7 @@
 .. image:: https://readthedocs.org/projects/importlib-resources/badge/?version=latest
    :target: https://importlib-resources.readthedocs.io/en/latest/?badge=latest
 
-.. image:: https://img.shields.io/badge/skeleton-2024-informational
+.. image:: https://img.shields.io/badge/skeleton-2025-informational
    :target: https://blog.jaraco.com/skeleton
 
 .. image:: https://tidelift.com/badges/package/pypi/importlib-resources
diff --git a/docs/conf.py b/docs/conf.py
index 64ea3d5..570346b 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-
 extensions = [
     'sphinx.ext.autodoc',
     'jaraco.packaging.sphinx',
@@ -28,8 +27,12 @@
                 url='https://peps.python.org/pep-{pep_number:0>4}/',
             ),
             dict(
-                pattern=r'(python/cpython#|Python #|bpo-)(?P<python>\d+)',
-                url='http://bugs.python.org/issue{python}',
+                pattern=r'(python/cpython#|Python #)(?P<python>\d+)',
+                url='https://github.com/python/cpython/issues/{python}',
+            ),
+            dict(
+                pattern=r'bpo-(?P<bpo>\d+)',
+                url='http://bugs.python.org/issue{bpo}',
             ),
         ],
     ),
diff --git a/importlib_resources/__init__.py b/importlib_resources/__init__.py
index 723c9f9..27d6c7f 100644
--- a/importlib_resources/__init__.py
+++ b/importlib_resources/__init__.py
@@ -8,12 +8,11 @@
 """
 
 from ._common import (
+    Anchor,
+    Package,
     as_file,
     files,
-    Package,
-    Anchor,
 )
-
 from ._functional import (
     contents,
     is_resource,
@@ -23,10 +22,8 @@
     read_binary,
     read_text,
 )
-
 from .abc import ResourceReader
 
-
 __all__ = [
     'Package',
     'Anchor',
diff --git a/importlib_resources/_common.py b/importlib_resources/_common.py
index f065d49..5f41c26 100644
--- a/importlib_resources/_common.py
+++ b/importlib_resources/_common.py
@@ -1,15 +1,15 @@
+import contextlib
+import functools
+import importlib
+import inspect
+import itertools
 import os
 import pathlib
 import tempfile
-import functools
-import contextlib
 import types
-import importlib
-import inspect
 import warnings
-import itertools
+from typing import Optional, Union, cast
 
-from typing import Union, Optional, cast
 from .abc import ResourceReader, Traversable
 
 Package = Union[types.ModuleType, str]
diff --git a/importlib_resources/_functional.py b/importlib_resources/_functional.py
index f59416f..5a3ca0a 100644
--- a/importlib_resources/_functional.py
+++ b/importlib_resources/_functional.py
@@ -2,8 +2,7 @@
 
 import warnings
 
-from ._common import files, as_file
-
+from ._common import as_file, files
 
 _MISSING = object()
 
diff --git a/importlib_resources/abc.py b/importlib_resources/abc.py
index 7a58dd2..84631c7 100644
--- a/importlib_resources/abc.py
+++ b/importlib_resources/abc.py
@@ -1,12 +1,25 @@
 import abc
-import io
 import itertools
+import os
 import pathlib
-from typing import Any, BinaryIO, Iterable, Iterator, NoReturn, Text, Optional
-from typing import runtime_checkable, Protocol
-
-from .compat.py38 import StrPath
-
+from typing import (
+    Any,
+    BinaryIO,
+    Iterable,
+    Iterator,
+    NoReturn,
+    Optional,
+    Protocol,
+    Text,
+    TextIO,
+    Union,
+    overload,
+    runtime_checkable,
+)
+
+from typing_extensions import Literal
+
+StrPath = Union[str, os.PathLike[str]]
 
 __all__ = ["ResourceReader", "Traversable", "TraversableResources"]
 
@@ -130,8 +143,16 @@ def __truediv__(self, child: StrPath) -> "Traversable":
         """
         return self.joinpath(child)
 
+    @overload
+    def open(self, mode: Literal['r'] = 'r', *args: Any, **kwargs: Any) -> TextIO: ...
+
+    @overload
+    def open(self, mode: Literal['rb'], *args: Any, **kwargs: Any) -> BinaryIO: ...
+
     @abc.abstractmethod
-    def open(self, mode='r', *args, **kwargs):
+    def open(
+        self, mode: str = 'r', *args: Any, **kwargs: Any
+    ) -> Union[TextIO, BinaryIO]:
         """
         mode may be 'r' or 'rb' to open as text or binary. Return a handle
         suitable for reading (same as pathlib.Path.open).
@@ -158,7 +179,7 @@ class TraversableResources(ResourceReader):
     def files(self) -> "Traversable":
         """Return a Traversable object for the loaded package."""
 
-    def open_resource(self, resource: StrPath) -> io.BufferedReader:
+    def open_resource(self, resource: StrPath) -> BinaryIO:
         return self.files().joinpath(resource).open('rb')
 
     def resource_path(self, resource: Any) -> NoReturn:
diff --git a/importlib_resources/compat/py38.py b/importlib_resources/compat/py38.py
deleted file mode 100644
index 4d54825..0000000
--- a/importlib_resources/compat/py38.py
+++ /dev/null
@@ -1,11 +0,0 @@
-import os
-import sys
-
-from typing import Union
-
-
-if sys.version_info >= (3, 9):
-    StrPath = Union[str, os.PathLike[str]]
-else:
-    # PathLike is only subscriptable at runtime in 3.9+
-    StrPath = Union[str, "os.PathLike[str]"]
diff --git a/importlib_resources/compat/py39.py b/importlib_resources/compat/py39.py
index ed5abd5..684d3c6 100644
--- a/importlib_resources/compat/py39.py
+++ b/importlib_resources/compat/py39.py
@@ -1,6 +1,5 @@
 import sys
 
-
 __all__ = ['ZipPath']
 
 
diff --git a/importlib_resources/future/adapters.py b/importlib_resources/future/adapters.py
index 0e9764b..239e52b 100644
--- a/importlib_resources/future/adapters.py
+++ b/importlib_resources/future/adapters.py
@@ -3,7 +3,7 @@
 from contextlib import suppress
 from types import SimpleNamespace
 
-from .. import readers, _adapters
+from .. import _adapters, readers
 
 
 def _block_standard(reader_getter):
@@ -23,6 +23,13 @@ def wrapper(*args, **kwargs):
         except NotADirectoryError:
             # MultiplexedPath may fail on zip subdirectory
             return
+        except ValueError as exc:
+            # NamespaceReader in stdlib may fail for editable installs
+            # (python/importlib_resources#311, python/importlib_resources#318)
+            # Remove after bugfix applied to Python 3.13.
+            if "not enough values to unpack" not in str(exc):
+                raise
+            return
         # Python 3.10+
         mod_name = reader.__class__.__module__
         if mod_name.startswith('importlib.') and mod_name.endswith('readers'):
diff --git a/importlib_resources/readers.py b/importlib_resources/readers.py
index 4f761c6..99884b6 100644
--- a/importlib_resources/readers.py
+++ b/importlib_resources/readers.py
@@ -3,14 +3,13 @@
 import collections
 import contextlib
 import itertools
-import pathlib
 import operator
+import pathlib
 import re
 import warnings
 from collections.abc import Iterator
 
 from . import abc
-
 from ._itertools import only
 from .compat.py39 import ZipPath
 
diff --git a/importlib_resources/tests/_path.py b/importlib_resources/tests/_path.py
index b144628..0033983 100644
--- a/importlib_resources/tests/_path.py
+++ b/importlib_resources/tests/_path.py
@@ -1,10 +1,6 @@
-import pathlib
 import functools
-
-from typing import Dict, Union
-from typing import runtime_checkable
-from typing import Protocol
-
+import pathlib
+from typing import Dict, Protocol, Union, runtime_checkable
 
 ####
 # from jaraco.path 3.7.1
diff --git a/importlib_resources/tests/test_compatibilty_files.py b/importlib_resources/tests/test_compatibilty_files.py
index 13ad0df..e8aac28 100644
--- a/importlib_resources/tests/test_compatibilty_files.py
+++ b/importlib_resources/tests/test_compatibilty_files.py
@@ -2,7 +2,6 @@
 import unittest
 
 import importlib_resources as resources
-
 from importlib_resources._adapters import (
     CompatibilityFiles,
     wrap_spec,
diff --git a/importlib_resources/tests/test_contents.py b/importlib_resources/tests/test_contents.py
index 741a740..dcb872e 100644
--- a/importlib_resources/tests/test_contents.py
+++ b/importlib_resources/tests/test_contents.py
@@ -1,4 +1,5 @@
 import unittest
+
 import importlib_resources as resources
 
 from . import util
diff --git a/importlib_resources/tests/test_custom.py b/importlib_resources/tests/test_custom.py
index 86c6567..25ae0e7 100644
--- a/importlib_resources/tests/test_custom.py
+++ b/importlib_resources/tests/test_custom.py
@@ -1,10 +1,11 @@
-import unittest
 import contextlib
 import pathlib
+import unittest
 
 import importlib_resources as resources
+
 from .. import abc
-from ..abc import TraversableResources, ResourceReader
+from ..abc import ResourceReader, TraversableResources
 from . import util
 from .compat.py39 import os_helper
 
diff --git a/importlib_resources/tests/test_files.py b/importlib_resources/tests/test_files.py
index f1fe233..be20660 100644
--- a/importlib_resources/tests/test_files.py
+++ b/importlib_resources/tests/test_files.py
@@ -1,17 +1,16 @@
-import os
+import contextlib
+import importlib
 import pathlib
 import py_compile
-import shutil
 import textwrap
 import unittest
 import warnings
-import importlib
-import contextlib
 
 import importlib_resources as resources
+
 from ..abc import Traversable
 from . import util
-from .compat.py39 import os_helper, import_helper
+from .compat.py39 import import_helper, os_helper
 
 
 @contextlib.contextmanager
@@ -72,7 +71,7 @@ def test_non_paths_in_dunder_path(self):
         to cause the ``PathEntryFinder`` to be called when searching
         for packages. In that case, resources should still be loadable.
         """
-        import namespacedata01
+        import namespacedata01  # type: ignore[import-not-found]
 
         namespacedata01.__path__.append(
             '__editable__.sample_namespace-1.0.finder.__path_hook__'
@@ -154,18 +153,19 @@ def test_implicit_files_submodule(self):
     def _compile_importlib(self):
         """
         Make a compiled-only copy of the importlib resources package.
+
+        Currently only code is copied, as importlib resources doesn't itself
+        have any resources.
         """
         bin_site = self.fixtures.enter_context(os_helper.temp_dir())
         c_resources = pathlib.Path(bin_site, 'c_resources')
         sources = pathlib.Path(resources.__file__).parent
-        shutil.copytree(sources, c_resources, ignore=lambda *_: ['__pycache__'])
-
-        for dirpath, _, filenames in os.walk(c_resources):
-            for filename in filenames:
-                source_path = pathlib.Path(dirpath) / filename
-                cfile = source_path.with_suffix('.pyc')
-                py_compile.compile(source_path, cfile)
-                pathlib.Path.unlink(source_path)
+
+        for source_path in sources.glob('**/*.py'):
+            c_path = c_resources.joinpath(source_path.relative_to(sources)).with_suffix(
+                '.pyc'
+            )
+            py_compile.compile(source_path, c_path)
         self.fixtures.enter_context(import_helper.DirsOnSysPath(bin_site))
 
     def test_implicit_files_with_compiled_importlib(self):
diff --git a/importlib_resources/tests/test_functional.py b/importlib_resources/tests/test_functional.py
index 1851edf..2285389 100644
--- a/importlib_resources/tests/test_functional.py
+++ b/importlib_resources/tests/test_functional.py
@@ -1,12 +1,11 @@
-import unittest
-import os
 import importlib
-
-from .compat.py39 import warnings_helper
+import os
+import unittest
 
 import importlib_resources as resources
 
 from . import util
+from .compat.py39 import warnings_helper
 
 # Since the functional API forwards to Traversable, we only test
 # filesystem resources here -- not zip files, namespace packages etc.
@@ -182,17 +181,23 @@ def test_contents(self):
             set(c),
             {'utf-8.file', 'utf-16.file', 'binary.file', 'subdirectory'},
         )
-        with self.assertRaises(OSError), warnings_helper.check_warnings((
-            ".*contents.*",
-            DeprecationWarning,
-        )):
+        with (
+            self.assertRaises(OSError),
+            warnings_helper.check_warnings((
+                ".*contents.*",
+                DeprecationWarning,
+            )),
+        ):
             list(resources.contents(self.anchor01, 'utf-8.file'))
 
         for path_parts in self._gen_resourcetxt_path_parts():
-            with self.assertRaises(OSError), warnings_helper.check_warnings((
-                ".*contents.*",
-                DeprecationWarning,
-            )):
+            with (
+                self.assertRaises(OSError),
+                warnings_helper.check_warnings((
+                    ".*contents.*",
+                    DeprecationWarning,
+                )),
+            ):
                 list(resources.contents(self.anchor01, *path_parts))
         with warnings_helper.check_warnings((".*contents.*", DeprecationWarning)):
             c = resources.contents(self.anchor01, 'subdirectory')
diff --git a/importlib_resources/tests/test_open.py b/importlib_resources/tests/test_open.py
index c40bb8c..8a4b68e 100644
--- a/importlib_resources/tests/test_open.py
+++ b/importlib_resources/tests/test_open.py
@@ -1,6 +1,7 @@
 import unittest
 
 import importlib_resources as resources
+
 from . import util
 
 
diff --git a/importlib_resources/tests/test_path.py b/importlib_resources/tests/test_path.py
index 1e30f2b..0be673d 100644
--- a/importlib_resources/tests/test_path.py
+++ b/importlib_resources/tests/test_path.py
@@ -3,6 +3,7 @@
 import unittest
 
 import importlib_resources as resources
+
 from . import util
 
 
diff --git a/importlib_resources/tests/test_read.py b/importlib_resources/tests/test_read.py
index 6780a2d..216c8fe 100644
--- a/importlib_resources/tests/test_read.py
+++ b/importlib_resources/tests/test_read.py
@@ -1,8 +1,9 @@
 import unittest
+from importlib import import_module
+
 import importlib_resources as resources
 
 from . import util
-from importlib import import_module
 
 
 class CommonBinaryTests(util.CommonTests, unittest.TestCase):
diff --git a/importlib_resources/tests/test_reader.py b/importlib_resources/tests/test_reader.py
index 0a77eb4..f8cfd8d 100644
--- a/importlib_resources/tests/test_reader.py
+++ b/importlib_resources/tests/test_reader.py
@@ -1,8 +1,8 @@
 import os.path
 import pathlib
 import unittest
-
 from importlib import import_module
+
 from importlib_resources.readers import MultiplexedPath, NamespaceReader
 
 from . import util
diff --git a/importlib_resources/tests/test_resource.py b/importlib_resources/tests/test_resource.py
index a0da6a3..c80afdc 100644
--- a/importlib_resources/tests/test_resource.py
+++ b/importlib_resources/tests/test_resource.py
@@ -1,8 +1,9 @@
 import unittest
+from importlib import import_module
+
 import importlib_resources as resources
 
 from . import util
-from importlib import import_module
 
 
 class ResourceTests:
diff --git a/importlib_resources/tests/util.py b/importlib_resources/tests/util.py
index a4eafac..07d1529 100644
--- a/importlib_resources/tests/util.py
+++ b/importlib_resources/tests/util.py
@@ -1,18 +1,16 @@
 import abc
+import contextlib
 import importlib
 import io
+import pathlib
 import sys
 import types
-import pathlib
-import contextlib
+from importlib.machinery import ModuleSpec
 
 from ..abc import ResourceReader
-from .compat.py39 import import_helper, os_helper
-from . import zip as zip_
 from . import _path
-
-
-from importlib.machinery import ModuleSpec
+from . import zip as zip_
+from .compat.py39 import import_helper, os_helper
 
 
 class Reader(ResourceReader):
@@ -145,7 +143,7 @@ def test_useless_loader(self):
     data01={
         '__init__.py': '',
         'binary.file': bytes(range(4)),
-        'utf-16.file': 'Hello, UTF-16 world!\n'.encode('utf-16'),
+        'utf-16.file': '\ufeffHello, UTF-16 world!\n'.encode('utf-16-le'),
         'utf-8.file': 'Hello, UTF-8 world!\n'.encode('utf-8'),
         'subdirectory': {
             '__init__.py': '',
@@ -160,7 +158,7 @@ def test_useless_loader(self):
     },
     namespacedata01={
         'binary.file': bytes(range(4)),
-        'utf-16.file': 'Hello, UTF-16 world!\n'.encode('utf-16'),
+        'utf-16.file': '\ufeffHello, UTF-16 world!\n'.encode('utf-16-le'),
         'utf-8.file': 'Hello, UTF-8 world!\n'.encode('utf-8'),
         'subdirectory': {
             'binary.file': bytes(range(12, 16)),
diff --git a/pyproject.toml b/pyproject.toml
index ec5312d..608e751 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,7 +19,7 @@ classifiers = [
 	"Programming Language :: Python :: 3",
 	"Programming Language :: Python :: 3 :: Only",
 ]
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 dependencies = [
 	"zipp >= 3.1.0; python_version < '3.10'",
 ]
@@ -74,7 +74,3 @@ type = [
 
 
 [tool.setuptools_scm]
-
-
-[tool.pytest-enabler.mypy]
-# Disabled due to jaraco/skeleton#143
diff --git a/ruff.toml b/ruff.toml
index 922aa1f..9379d6e 100644
--- a/ruff.toml
+++ b/ruff.toml
@@ -1,3 +1,6 @@
+# extend pyproject.toml for requires-python (workaround astral-sh/ruff#10299)
+extend = "pyproject.toml"
+
 [lint]
 extend-select = [
 	"C901",
diff --git a/tox.ini b/tox.ini
index 01f0975..1424305 100644
--- a/tox.ini
+++ b/tox.ini
@@ -31,9 +31,7 @@ extras =
 changedir = docs
 commands =
 	python -m sphinx -W --keep-going . {toxinidir}/build/html
-	python -m sphinxlint \
-		# workaround for sphinx-contrib/sphinx-lint#83
-		--jobs 1
+	python -m sphinxlint
 
 [testenv:finalize]
 description = assemble changelog and tag a release