diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 3d725a50..c79c0de8 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -2,13 +2,7 @@
 version: 2
 updates:
 - package-ecosystem: pip
-  directory: /dependencies/default
-  schedule:
-    interval: weekly
-  open-pull-requests-limit: 10
-  target-branch: main
-- package-ecosystem: pip
-  directory: /dependencies/docs
+  directory: /
   schedule:
     interval: weekly
   open-pull-requests-limit: 10
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 14e2361d..f55f1d27 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -16,8 +16,8 @@ env:
   PYTHON_LATEST: 3.13
 
 jobs:
-  lint:
-    name: Run linters
+  build:
+    name: Build package
     runs-on: ubuntu-latest
     outputs:
       version: ${{ steps.version.outputs.version }}
@@ -30,23 +30,12 @@ jobs:
     - uses: actions/setup-python@v5
       with:
         python-version: ${{ env.PYTHON_LATEST }}
-    - name: Install GitHub matcher for ActionLint checker
-      run: |
-        echo "::add-matcher::.github/actionlint-matcher.json"
-    - name: Install pre-commit
-      run: python -m pip install pre-commit
-    - name: Run pre-commit checks
-      run: pre-commit run --all-files --show-diff-on-failure
-    - name: Install check-wheel-content, and twine
-      run: python -m pip install build check-wheel-contents twine
-    - name: Build package
-      run: python -m build
+    - name: Install tox
+      run: python -m pip install tox
+    - name: Build package and check distributions
+      run: tox run -e build
     - name: List result
       run: ls -l dist
-    - name: Check wheel contents
-      run: check-wheel-contents dist/*.whl
-    - name: Check long_description
-      run: python -m twine check dist/*
     - name: Install pytest-asyncio
       run: pip install .
     - name: Get version info
@@ -58,6 +47,25 @@ jobs:
         name: dist
         path: dist
 
+  lint:
+    name: Run linters
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v5
+      with:
+        fetch-depth: 0
+        persist-credentials: false
+    - uses: actions/setup-python@v5
+      with:
+        python-version: ${{ env.PYTHON_LATEST }}
+    - name: Install GitHub matcher for ActionLint checker
+      run: |
+        echo "::add-matcher::.github/actionlint-matcher.json"
+    - name: Install pre-commit
+      run: python -m pip install pre-commit
+    - name: Run pre-commit checks
+      run: pre-commit run --all-files --show-diff-on-failure
+
   test:
     name: ${{ matrix.os }} - Python ${{ matrix.python-version }}
     runs-on: ${{ matrix.os }}-latest
@@ -109,7 +117,7 @@ jobs:
   check:
     name: Check
     if: always()
-    needs: [lint, test]
+    needs: [build, lint, test]
     runs-on: ubuntu-latest
     steps:
     - name: Decide whether the needed jobs succeeded or failed
@@ -145,7 +153,7 @@ jobs:
 
   create-github-release:
     name: Create GitHub release
-    needs: [lint, check]
+    needs: [build, lint, check]
     runs-on: ubuntu-latest
     permissions:
       contents: write
@@ -168,7 +176,7 @@ jobs:
       if: ${{ !contains(github.ref, 'refs/tags/') }}
       run: towncrier build --draft --version "${version}" > release-notes.rst
       env:
-        version: ${{ needs.lint.outputs.version }}
+        version: ${{ needs.build.outputs.version }}
     - name: Extract release notes from Git tag
       if: github.event_name == 'push' && contains(github.ref, 'refs/tags/')
       run: |
@@ -194,16 +202,16 @@ jobs:
       if: github.event_name == 'push' && contains(github.ref, 'refs/tags/')
       uses: ncipollo/release-action@bcfe5470707e8832e12347755757cec0eb3c22af  # v1.18.0
       with:
-        name: pytest-asyncio ${{ needs.lint.outputs.version }}
+        name: pytest-asyncio ${{ needs.build.outputs.version }}
         artifacts: dist/*
         bodyFile: release-notes.md
-        prerelease: ${{ needs.lint.outputs.prerelease }}
+        prerelease: ${{ needs.build.outputs.prerelease }}
         token: ${{ secrets.GITHUB_TOKEN }}
 
   publish-test-pypi:
     name: Publish packages to test.pypi.org
     if: github.event_name == 'push' && github.ref == 'refs/heads/main'
-    needs: [lint, check]
+    needs: [build, lint, check]
     runs-on: ubuntu-latest
     permissions:
       id-token: write
@@ -222,7 +230,7 @@ jobs:
     name: Publish packages to pypi.org
     environment: release
     if: github.event_name == 'push' && contains(github.ref, 'refs/tags/')
-    needs: [lint, check]
+    needs: [build, lint, check]
     runs-on: ubuntu-latest
     permissions:
       id-token: write
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 16938eaa..77dc1773 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -72,7 +72,7 @@ repos:
   hooks:
   - id: pyproject-fmt
       # https://pyproject-fmt.readthedocs.io/en/latest/#calculating-max-supported-python-version
-    additional_dependencies: [tox>=4.9]
+    additional_dependencies: [tox>=4.28]
 - repo: https://github.com/zizmorcore/zizmor-pre-commit
   rev: v1.12.1
   hooks:
diff --git a/changelog.d/+dc5bb56e.downstream.rst b/changelog.d/+dc5bb56e.downstream.rst
new file mode 100644
index 00000000..6bb210bb
--- /dev/null
+++ b/changelog.d/+dc5bb56e.downstream.rst
@@ -0,0 +1 @@
+Bump the minimum required version of tox to v4.28. This change is only relevant if you use the ``tox.ini`` file provided by pytest-asyncio to run tests.
diff --git a/constraints.txt b/constraints.txt
new file mode 100644
index 00000000..0e696c64
--- /dev/null
+++ b/constraints.txt
@@ -0,0 +1,66 @@
+alabaster==0.7.16
+annotated-types-0.7.0
+attrs==25.3.0
+babel==2.17.0
+backports.asyncio.runner==1.2.0
+backports.tarfile==1.2.0
+certifi==2025.8.3
+charset-normalizer==3.4.3
+check-wheel-contents==0.6.1
+cffi==1.17.1
+click==8.1.8
+coverage==7.10.4
+cryptography==45.0.6
+docutils==0.21.2
+exceptiongroup==1.3.0
+hypothesis==6.138.2
+iniconfig==2.1.0
+id==1.5.0
+idna==3.10
+imagesize==1.4.1
+importlib_metadata==8.7.0
+iniconfig==2.1.0
+jaraco.classes==3.4.0
+jaraco.context==6.0.1
+jaraco.functools==4.3.0
+jeepney==0.9.0
+Jinja2==3.1.6
+keyring==25.6.0
+markdown-it-py==3.0.0
+MarkupSafe==3.0.2
+mdurl==0.1.2
+more-itertools==10.7.0
+nh3==0.3.0
+packaging==25.0
+pluggy==1.6.0
+Pygments==2.19.2
+pycparser==2.22
+pydantic==2.11.7
+pydantic-core==2.33.2
+pytest==8.4.1
+readme-renderer==44.0
+requests==2.32.4
+requests-toolbelt==1.0.0
+rfc3986==2.0.0
+rich==14.1.0
+SecretStorage==3.3.3
+setuptools==80.9.0
+setuptools-scm==8.3.0
+snowballstemmer==3.0.1
+sortedcontainers==2.4.0
+Sphinx==8.0.2
+sphinx-rtd-theme==3.0.2
+sphinxcontrib-applehelp==2.0.0
+sphinxcontrib-devhelp==2.0.0
+sphinxcontrib-htmlhelp==2.1.0
+sphinxcontrib-jquery==4.1
+sphinxcontrib-jsmath==1.0.1
+sphinxcontrib-qthelp==2.0.0
+sphinxcontrib-serializinghtml==2.0.0
+tomli==2.2.1
+twine==6.1.0
+typing_extensions==4.14.1
+typing-inspection==0.4.1
+urllib3==2.5.0
+wheel-filename==1.4.2
+zipp==3.23.0
diff --git a/dependencies/default/constraints.txt b/dependencies/default/constraints.txt
deleted file mode 100644
index 4db129fb..00000000
--- a/dependencies/default/constraints.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-attrs==25.3.0
-coverage==7.10.4
-exceptiongroup==1.3.0
-hypothesis==6.138.2
-iniconfig==2.1.0
-packaging==25.0
-pluggy==1.6.0
-pytest==8.4.1
-sortedcontainers==2.4.0
-tomli==2.2.1
-typing_extensions==4.14.1
diff --git a/dependencies/default/requirements.txt b/dependencies/default/requirements.txt
deleted file mode 100644
index 42cfc8d3..00000000
--- a/dependencies/default/requirements.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-# Always adjust install_requires in setup.cfg and pytest-min-requirements.txt
-# when changing runtime dependencies
-pytest >= 8.2,<9
diff --git a/dependencies/docs/constraints.txt b/dependencies/docs/constraints.txt
deleted file mode 100644
index c4524c4b..00000000
--- a/dependencies/docs/constraints.txt
+++ /dev/null
@@ -1,23 +0,0 @@
-alabaster==0.7.16
-Babel==2.17.0
-certifi==2025.8.3
-charset-normalizer==3.4.3
-docutils==0.21.2
-idna==3.10
-imagesize==1.4.1
-Jinja2==3.1.6
-MarkupSafe==3.0.2
-packaging==25.0
-Pygments==2.19.2
-requests==2.32.4
-snowballstemmer==3.0.1
-Sphinx==8.0.2
-sphinx-rtd-theme==3.0.2
-sphinxcontrib-applehelp==2.0.0
-sphinxcontrib-devhelp==2.0.0
-sphinxcontrib-htmlhelp==2.1.0
-sphinxcontrib-jquery==4.1
-sphinxcontrib-jsmath==1.0.1
-sphinxcontrib-qthelp==2.0.0
-sphinxcontrib-serializinghtml==2.0.0
-urllib3==2.5.0
diff --git a/dependencies/docs/requirements.txt b/dependencies/docs/requirements.txt
deleted file mode 100644
index 1bfd7f50..00000000
--- a/dependencies/docs/requirements.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-sphinx >= 5.3
-sphinx-rtd-theme >= 1.0
diff --git a/pyproject.toml b/pyproject.toml
index d3c5b6bf..e3809be1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,8 +1,8 @@
 [build-system]
 build-backend = "setuptools.build_meta"
 requires = [
-  "setuptools==80.9",
-  "setuptools-scm==9.2",
+  "setuptools>=77",
+  "setuptools-scm[toml]>=6.2",
 ]
 
 [project]
diff --git a/tox.ini b/tox.ini
index 3608cc56..b6121581 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,26 +1,41 @@
 [tox]
-minversion = 4.9.0
-envlist = py39, py310, py311, py312, py313, py314, pytest-min, docs, pyright
+minversion = 4.28.0
+envlist = build, py39, py310, py311, py312, py313, py314, pytest-min, docs, pyright
 isolated_build = true
 passenv =
     CI
 
+[pkgenv]
+constraints = constraints.txt
+
 [testenv]
+package = external
 extras = testing
-install_command = python -m pip install \
-    --requirement dependencies/default/requirements.txt \
-    --constraint dependencies/default/constraints.txt \
-    {opts} {packages}
+constraints = constraints.txt
 commands = make test
 allowlist_externals =
     make
 
+[testenv:.pkg_external]
+deps = build
+package_glob = {toxinidir}{/}dist{/}*.whl
+commands =
+    python -c 'import shutil; shutil.rmtree("{toxinidir}{/}dist", ignore_errors=True)'
+    pyproject-build --outdir {toxinidir}{/}dist .
+
+[testenv:build]
+description = Check distribution files
+deps =
+    check-wheel-contents
+    twine
+commands =
+    check-wheel-contents {toxinidir}{/}dist
+    twine check {toxinidir}{/}dist{/}*
+
 [testenv:pytest-min]
 extras = testing
-install_command = python -m pip install \
-    --requirement dependencies/pytest-min/requirements.txt \
-    --constraint dependencies/pytest-min/constraints.txt \
-    {opts} {packages}
+constraints = dependencies/pytest-min/constraints.txt
+deps = -r dependencies/pytest-min/requirements.txt
 commands = make test
 allowlist_externals =
     make
@@ -29,9 +44,6 @@ allowlist_externals =
 allowlist_externals =
     git
 extras = docs
-deps =
-     --requirement dependencies/docs/requirements.txt
-     --constraint dependencies/docs/constraints.txt
 change_dir = docs
 description = Build The Docs with {basepython}
 commands =
@@ -78,7 +90,7 @@ skip_install = true
 
 [gh-actions]
 python =
-    3.9: py39, pytest-min
+    3.9: py39, pytest-min, build
     3.10: py310
     3.11: py311
     3.12: py312