[bashtage]

Moves the development configuration of arch into pyproject.toml, following the same change in randomgen 2.5.0. Each tool now has its settings in one place, and nothing says "keep synced with" another file any more. The minimum versions of arch and its dependencies are unchanged, and the wheel declares exactly the same Requires-Dist.

Commits

1. MAINT: Replace flake8 with ruff. ruff already covers pyflakes, the pycodestyle errors and warnings it implements, and flake8-bugbear, while black handles the whitespace checks. The one extra check flake8 made, the 99-character limit on comments, docstrings and long strings, is now ruff's E501 with [tool.ruff.lint.pycodestyle] max-line-length = 99. black stays at 88. Removes .flake8 and the flake8 Lint step.

2. MAINT: Move the development requirements into dependency groups. PEP 735 groups replace requirements.txt, requirements-dev.txt, doc/requirements.txt, the simulation scripts' requirements.txt, and the test/doc/dev extras. pip 25.1 or later installs them with --group:

   • build: what pip install -e . --no-build-isolation needs
   • test: pytest, pytest-xdist, pytest-cov and coverage
   • notebooks: what the example notebooks need
   • lint: black, isort, ruff, mypy and the type stubs
   • docstrings: numpydoc, which test and lint include
   • dev: build, test, lint and notebooks, plus matplotlib, seaborn and pytest-randomly
   • doc: what the documentation needs, on top of dev
   • simulation: what the critical value simulation scripts need

   CI installs the groups. The Lint workflow now uses the versions pinned in the lint group (black 26.10.1, isort 9.0, ruff 0.17.4 or later), which are the versions its unpinned install picks today.

3. MAINT: Move the coverage settings into pyproject.toml. coverage reads .coveragerc before pyproject.toml, so the [tool.coverage] tables were never used. .coveragerc is removed, and CI no longer passes --cov-config.

4. MAINT: Clean up the tool settings in pyproject.toml.

   • black and ruff take their target Python from requires-python.
   • The two mypy sections that used setup.cfg names, which mypy ignores, are now real overrides.
   • Fixes a typo in black's exclude list, and adds the "3 :: Only" classifier and an issues URL.
   • Removes .gitattributes, whose only line applied to arch/_version.py, a file git doesn't track.

5. DOC: Add a release note under "Documentation and maintenance".

Left outside pyproject.toml

• meson.build and meson.options: meson can't read pyproject.toml.
• codecov.yml and .codacy.yml: those services read only their own files.
• The CI files and docs build files.
• Three build pins (Cython, meson-python, setuptools-scm) appear in both [build-system].requires and the build group, because a group can't include the build requirements. A comment says so.

CI changes to be aware of

• Azure Windows installs only the build and test groups. It no longer installs pytest-randomly, so the fast tests run in a fixed order, as on Linux. The linters, Sphinx and jupyter are no longer installed there either.
• Windows ARM installs the test group, which adds numpydoc, so test_docstrings.py now runs there.
• Azure Linux installs the groups in the same pip command as the exact versions of numpy, scipy and the rest. In the conda job, pip installs the groups after the conda packages.
• Coverage: [tool.coverage] has a few more exclusions than .coveragerc had and omits conftest.py, so the coverage figure may rise slightly.

Checks

• Lint: ruff check arch, black --check arch, isort --check and numpydoc lint are all clean with the new settings.
• ruff format: it would reformat 6 files, so black stays.
• Builds: python -m build (an isolated sdist, then the wheel built from the sdist) and a no-binary wheel built from the sdist all pass twine check --strict. The sdist contains none of the removed files.
• Fast suite: 31,582 passed (Windows, Python 3.14).
• Installed wheel: run from outside the source tree, its tests pass.
• Docs: built in a fresh environment set up only with pip install --group dev --group doc plus the wheel, with no Sphinx warnings.
• Dependency groups: a dry-run install resolves for the setup of every Azure, Windows ARM, Lint and docs job.
• arch-wheels: its build-wheels.yml doesn't depend on any moved or removed file.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.51%. Comparing base (b7c5046) to head (4ec3bc5).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1021      +/-   ##
==========================================
+ Coverage   99.44%   99.51%   +0.06%     
==========================================
  Files         153      152       -1     
  Lines       34278    34209      -69     
  Branches     2595     2588       -7     
==========================================
- Hits        34088    34043      -45     
+ Misses        114       94      -20     
+ Partials       76       72       -4     

Flag	Coverage Δ
adder	99.45% <ø> (+0.06%)	⬆️
subtractor	99.45% <ø> (+0.06%)	⬆️

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