style: adopt ruff (format + lint) at 88, replacing black/isort/flake8

Format-only: Python files are AST-identical apart from import order.
pre-commit end-of-file/trailing-whitespace fixes applied repo-wide.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.flake8

@@ -1,11 +0,0 @@
-[flake8]
-max-line-length=120
-ignore =
-    E121,
-    E123,
-    E126,
-    E226,
-    E24,
-    E704,
-    W605
-exclude = ./tests

.gitignore

@@ -3,4 +3,3 @@ dist
 *.egg-info
 __pycache__
 .idea
-

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v4.5.0
+    rev: v6.0.0
     hooks:
     -   id: check-yaml
     -   id: check-added-large-files
@@ -9,23 +9,10 @@ repos:
     -   id: end-of-file-fixer
     -   id: trailing-whitespace
 
-# isort -- sorts imports
--   repo: https://github.com/timothycrosley/isort
-    rev: 5.13.2
+# ruff replaces black, isort and flake8. Keep rev equal to the ruff pin in pyproject.toml.
+-   repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.16.10
     hooks:
-    -   id: isort
-        args: ["--profile", "black", "--filter-files"]
-
-# Flake8
--   repo: https://github.com/pycqa/flake8
-    rev: '7.0.0'
-    hooks:
-    -   id: flake8
-
-# Black
-# Using this mirror lets us use mypyc-compiled black, which is about 2x faster
-- repo: https://github.com/psf/black-pre-commit-mirror
-  rev: 24.2.0
-  hooks:
-    - id: black
-      language_version: python3.8
+    -   id: ruff-check
+        args: [--fix]
+    -   id: ruff-format

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## [0.2.2] (2020-07-19)
 
-Second release is focused on cleanup, documentation. 
+Second release is focused on cleanup, documentation.
 
  * flake8, black, isort - all warnings and errors fixed.
  * Documentation improved.
@@ -19,4 +19,3 @@ First release to PyPi.
  * Config through ConfigObj ini. Define spec file and input config.ini
  * Colored Logging
  * Services can be defined and provided to classes
-

CLAUDE.md

@@ -9,22 +9,20 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 ## Commands
 
 ```bash
-pip install -e '.[dev]' pytest   # dev extras = black, isort, flake8, pre-commit; pytest is NOT in the extras
+pip install -e '.[dev]' pytest   # dev extras = ruff, pre-commit; pytest is NOT in the extras
 pytest tests                     # full suite from repo root (or `pytest .` from inside tests/)
 pytest tests/cfg/test_cfg.py::TestConfig_e2e::test_uses_spec_as_defaults   # single test
 pytest tests -k "<keyword>"
 
-black app_skellington
-isort --profile black app_skellington
-flake8 app_skellington           # .flake8: max-line-length 120, tests/ excluded
+ruff check --fix                 # lint + import sorting (config in pyproject.toml)
+ruff format                      # formatter, line length 88
 
 python -m build                  # sdist + wheel into dist/
 python -m setuptools_scm         # print the version the build will get
 ```
 
 - **Versioning is tag-driven.** setuptools_scm uses `release-branch-semver` and derives the version from the latest `vX.Y.Z` git tag. It writes `app_skellington/_version.py` at build time. That file is tracked, but don't hand-edit it. `pip install -e .` also rewrites it, so `git restore` it rather than committing the churn. A release means tagging, then `python -m build`, then `twine upload dist/*`. The README covers the full publish steps.
-- **Formatter config is inconsistent.** `pyproject.toml` has no `[tool.black]`, so black runs at its default width of 88. Only flake8 allows 120. The code on `main` is formatted at 88. The pre-commit black hook pins `language_version: python3.8`. It fails unless a 3.8 interpreter is on PATH (`.python-version` names 3.8.x for pyenv).
-- **Lint is not currently clean on `main`.** black wants to reformat 2 files, isort flags 3, and flake8 reports W391 and W503. Keep unrelated reformatting out of feature diffs.
+- **ruff** handles formatting (88 columns) and lint (`E`, `F`, `W`, `I`). E501 is ignored on purpose, since the formatter owns line length. Keep the `ruff==` pin in `pyproject.toml` equal to the `rev:` in `.pre-commit-config.yaml`.
 - Tests cover only `cfg` (ConfigObj fixtures live in `tests/cfg/`) plus a CommandTree constructor smoke test. `tests/test_log.py` is empty.
 
 ## Python support policy

app_skellington/app_container.py

@@ -4,13 +4,13 @@ import os
 
 import appdirs
 
-from ._util import ServiceNotFound, NoCommandSpecified, get_root_asset
 from . import log
-from .cfg import Config
-from .cli import CommandTree
 
 # Application scaffolding:
 from ._bootstrap import _bootstrap_logger
+from ._util import NoCommandSpecified, ServiceNotFound, get_root_asset
+from .cfg import Config
+from .cli import CommandTree
 
 # These two variables affect the directory paths for
 # config files and logging.
@@ -189,5 +189,3 @@ class ApplicationContainer:
     def usage(self):
         pass
         # Applications need a default usage
-
-

app_skellington/cfg.py

@@ -217,9 +217,9 @@ class Config:
         try:
             _bootstrap_logger.info("cfg - Validating config file against spec")
             val = validate.Validator()
-            assert isinstance(
-                self._config_obj, configobj.ConfigObj
-            ), "expecting configobj.ConfigObj, received %s" % type(self._config_obj)
+            assert isinstance(self._config_obj, configobj.ConfigObj), (
+                "expecting configobj.ConfigObj, received %s" % type(self._config_obj)
+            )
             # NOTE(MG) copy arg below instructs configobj to use defaults from spec file
             test_results = self._config_obj.validate(
                 val, copy=True, preserve_errors=True

app_skellington/cli.py

@@ -3,8 +3,8 @@ import inspect
 import re
 import sys
 
-from ._util import NoCommandSpecified
 from ._bootstrap import _bootstrap_logger
+from ._util import NoCommandSpecified
 
 # If explicit fail is enabled, any command with at least one unknown
 # argument will be rejected entirely. If not enabled, unknown arguments
@@ -233,22 +233,21 @@ class CommandTree:
         # the CommandTree with no SubMenu (submenu will be disabled
         # in this case):
         if self._cmd_tree_is_single_command:
-            assert (
-                self._cmd_tree_is_single_command is True
-            ), "corrupt data structure in CommandMenu"
+            assert self._cmd_tree_is_single_command is True, (
+                "corrupt data structure in CommandMenu"
+            )
             assert self._entries is None, "corrupt data structure in CommandMenu"
-            assert isinstance(
-                self._single_command, CommandEntry
-            ), "corrupt data structure in CommandMenu"
+            assert isinstance(self._single_command, CommandEntry), (
+                "corrupt data structure in CommandMenu"
+            )
             return self._single_command
 
         # There is at least one submenu we need to go down:
         else:
-
             assert self._single_command is None, "corrupt data structure in CommandMenu"
-            assert (
-                self._cmd_tree_is_single_command is False
-            ), "corrupt data structure in CommandMenu"
+            assert self._cmd_tree_is_single_command is False, (
+                "corrupt data structure in CommandMenu"
+            )
 
             # Key or variable name used by argparse to store the submenu options
             argparse_param = self.submenu_param  # e.g.: submenu_root

docs/superpowers/plans/2026-10-04-modernization-hotfix-track.md

@@ -160,7 +160,9 @@ def norm(src):
     tree = ast.parse(src)
     imports, rest = [], []
     for node in tree.body:
-        (imports if isinstance(node, (ast.Import, ast.ImportFrom)) else rest).append(node)
+        (imports if isinstance(node, (ast.Import, ast.ImportFrom)) else rest).append(
+            node
+        )
     for node in imports:
         node.names = sorted(node.names, key=lambda a: (a.name, a.asname or ""))
     return sorted(ast.dump(n) for n in imports), [ast.dump(n) for n in rest]
@@ -876,8 +878,7 @@ import pytest  # add to the imports
 
 
 @pytest.mark.skipif(not VERIFY_SCRIPT.exists(), reason="added with the release task")
-def test_verify_script_covers_matrix():
-    ...
+def test_verify_script_covers_matrix(): ...
 ```
 Run again. Expected: all pass, 1 skipped.
 

pyproject.toml

@@ -33,13 +33,26 @@ documentation = "https://git-repos.zavage.net/Zavage-Software/app_skellington"
 
 [project.optional-dependencies]
 dev = [
-    "black",
+    "ruff==0.16.10",
     "pre-commit",
-    "isort",
-    "flake8"
 ]
 
 [tool.setuptools_scm]
 version_file = "app_skellington/_version.py"
 version_scheme = "release-branch-semver"
 local_scheme = "node-and-date"
+
+[tool.ruff]
+line-length = 88
+target-version = "py38"
+extend-exclude = ["app_skellington/_version.py"]
+
+[tool.ruff.lint]
+# E/W = pycodestyle, F = pyflakes, I = isort: the old flake8 + isort coverage.
+select = ["E", "F", "W", "I"]
+# The formatter owns line length. Long strings and comments it can't wrap are allowed.
+ignore = ["E501"]
+
+[tool.ruff.lint.per-file-ignores]
+# Placeholder smoke test. The characterization-tests plan rewrites it.
+"tests/test_cli.py" = ["F841", "E712"]

setup.cfg

@@ -1,3 +1,2 @@
 [metadata]
 description-file = README.md
-

tests/README.md

@@ -15,4 +15,3 @@ Run test by keyword:
 Run test by directory:
 
     pytest <dirname>
-  

tests/cfg/sample_config.ini

@@ -2,4 +2,3 @@ root_option = root_option_val
 
 [app]
     sub_option = sub_option_val
-

tests/cfg/sample_config.spec

@@ -2,4 +2,3 @@ root_option = string(max=255, default='def_string')
 
 [app]
     sub_option = string(max=255, default='def_sub')
-

tests/cfg/sample_config_full.ini

@@ -2,4 +2,3 @@ root_option = root_option_val
 
 [app]
     sub_option = sub_option_val
-

tests/cfg/sample_config_full.spec

@@ -3,4 +3,3 @@ int_option = integer(min=0, max=100)
 
 [app]
     sub_option = string(max=255, default='def_sub')
-

tests/cfg/sample_config_invalid.spec

@@ -1,2 +1 @@
 root_option = invalid(max=255, default='def_string')
-

tests/cfg/test_cfg.py

@@ -32,18 +32,18 @@ def sample_invalid_configspec_filepath():
 class TestConfig_e2e:
     def test_allows_reading_ini_and_no_spec(self, sample_configini_filepath):
         cfg = Config(configini_filepath=sample_configini_filepath)
-        assert (
-            cfg["root_option"] == "root_option_val"
-        ), "expecting default from config.spec (didnt get)"
-        assert (
-            cfg["app"]["sub_option"] == "sub_option_val"
-        ), "expecting default for sub option"
+        assert cfg["root_option"] == "root_option_val", (
+            "expecting default from config.spec (didnt get)"
+        )
+        assert cfg["app"]["sub_option"] == "sub_option_val", (
+            "expecting default for sub option"
+        )
 
     def test_allows_reading_spec_and_no_ini(self, sample_configspec_filepath):
         cfg = Config(configspec_filepath=sample_configspec_filepath)
-        assert (
-            cfg["root_option"] == "def_string"
-        ), "expecting default from config.spec (didnt get)"
+        assert cfg["root_option"] == "def_string", (
+            "expecting default from config.spec (didnt get)"
+        )
 
     # NOTE(MG) Changed the functionality to not do it this way.
     # def test_constructor_fails_with_invalid_spec(
@@ -71,9 +71,9 @@ class TestConfig_e2e:
         assert cfg["root_option"] == "newval"
 
         cfg["app"]["sub_option"] = "another_new_val"
-        assert (
-            cfg["app"]["sub_option"] == "another_new_val"
-        ), "expecting default for sub option"
+        assert cfg["app"]["sub_option"] == "another_new_val", (
+            "expecting default for sub option"
+        )
 
     def test_can_set_option_without_config(self):
         cfg = Config()
@@ -86,7 +86,7 @@ class TestConfig_e2e:
 
     def test_uses_spec_as_defaults(self, sample_configspec_filepath):
         cfg = Config(configspec_filepath=sample_configspec_filepath)
-        assert (
-            cfg["root_option"] == "def_string"
-        ), "expecting default from config.spec (didnt get)"
+        assert cfg["root_option"] == "def_string", (
+            "expecting default from config.spec (didnt get)"
+        )
         assert cfg["app"]["sub_option"] == "def_sub", "expecting default for sub option"

tests/pytest.ini

@@ -1,4 +1,3 @@
 [pytest]
 filterwarnings =
     ignore::DeprecationWarning
-