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Overview

Apply a consistent format to your pyproject.toml file with comment support. See changelog here.

Recent Changes

  • 🐛 fix(build): write Requires-Dist into the METADATA header by @gaborbernat in #444 <a id="2.28.0"></a>

Philosophy

This is an opinionated formatter, with the same objectives as black: it offers few configuration settings on purpose. In return you get consistency, predictability, and smaller diffs.

Use

Via CLI

pyproject-fmt is a CLI tool that needs Python 3.10 or higher to run. Install it into an isolated environment with pipx or uv; that way you can upgrade pyproject-fmt later without disturbing the rest of your system. A pip path follows for completeness, though we discourage it:

# install uv per https://docs.astral.sh/uv/#getting-started
uv tool install pyproject-fmt
pyproject-fmt --help

Via pre-commit hook

See pre-commit/pre-commit for instructions, sample .pre-commit-config.yaml:

- repo: https://github.com/tox-dev/pyproject-fmt
  # Use the sha / tag you want to point at
  # or use `pre-commit autoupdate` to get the latest version
  rev: ""
  hooks:
    - id: pyproject-fmt

Via Python

Call pyproject-fmt as a Python module to format TOML from your own code.

from pyproject_fmt import run

# Format a pyproject.toml file and return the exit code
exit_code = run(["path/to/pyproject.toml"])

The run function accepts command-line arguments as a list and returns an exit code (0 for success, non-zero for failure).

The tool.pyproject-fmt table is used when present in the pyproject.toml file:

[tool.pyproject-fmt]

# After how many columns split arrays/dicts into multiple lines and wrap long strings;
# use a trailing comma in arrays to force multiline format instead of lowering this value
column_width = 120

# Number of spaces for indentation
indent = 2

# Keep full version numbers (e.g., 1.0.0 instead of 1.0) in dependency specifiers
keep_full_version = false

# Automatically generate Python version classifiers based on requires-python
# Set to false to disable automatic classifier generation
generate_python_version_classifiers = true

# Maximum Python version for generating version classifiers
max_supported_python = "3.14"

# Table format: "short" collapses sub-tables to dotted keys, "long" expands to
# [table.subtable] headers
table_format = "short"

# Extra newlines between sub-tables in the same group (e.g. "\n" for one blank line
# between sub-tables)
sub_table_spacing = ""

# Extra newlines between root table groups (e.g. "\n" for one blank line, "\n\n" for two)
separate_root_table = "\n"

# List of tables to force expand regardless of table_format setting
expand_tables = []

# List of tables to force collapse regardless of table_format or expand_tables settings
collapse_tables = []

# List of key patterns to skip string wrapping (supports wildcards like *.parse or
# tool.bumpversion.*)
skip_wrap_for_keys = []

If not set they will default to values from the CLI.

Shared configuration file

Place formatting settings in a standalone pyproject-fmt.toml file instead of (or alongside) the [tool.pyproject-fmt] table. In a monorepo this shares one configuration across projects without repeating it in every pyproject.toml.

The formatter searches for pyproject-fmt.toml from the directory of the file being formatted up to the filesystem root, and the first match wins. Pass an explicit path via --config:

pyproject-fmt --config /path/to/pyproject-fmt.toml pyproject.toml

The shared config file uses the same keys as the [tool.pyproject-fmt] table, but without the table header:

column_width = 120
indent = 2
table_format = "short"
sub_table_spacing = ""
separate_root_table = "\n"
max_supported_python = "3.14"

When both a shared config file and a [tool.pyproject-fmt] table exist, per-file settings from the [tool.pyproject-fmt] table take precedence over the shared config file.

Python version classifiers

This tool will automatically generate the Programming Language :: Python :: 3.X classifiers for you. To do so it needs to know the range of Python interpreter versions you support:

  • The lower bound can be set via the requires-python key in the pyproject.toml configuration file (defaults to the oldest non end of line CPython at the time of the release).
  • The upper bound, by default, will assume the latest stable release of CPython at the time of the release, but can be changed via CLI flag or the config file.

Table formatting

Note

Table formatting options are available in version 2.12.0 and later.

Control how sub-tables are formatted with two styles:

Short format (collapsed) - The default, where sub-tables collapse into dotted keys. Use it for a compact layout:

[project]
name = "myproject"
urls.homepage = "https://example.com"
urls.repository = "https://github.com/example/myproject"
scripts.mycli = "mypackage:main"

Long format (expanded) - Sub-tables are expanded into separate [table.subtable] sections. Use this for readability when tables have many keys or complex values:

# Before
[project]
name = "myproject"
urls.homepage = "https://example.com"
urls.repository = "https://github.com/example/myproject"
scripts.mycli = "mypackage:main"

# After
[project]
name = "myproject"
[project.urls]
homepage = "https://example.com"
repository = "https://github.com/example/myproject"
[project.scripts]
mycli = "mypackage:main"

Table spacing

The sub_table_spacing and separate_root_table options control the blank lines inserted between tables. Each option takes a string of \n characters where each \n adds one blank line:

  • sub_table_spacing (default "") controls spacing between sub-tables within the same group. For example, between [tool.ruff] and [tool.ruff.lint]. Set to "\n" to add a blank line between sub-tables.
  • separate_root_table (default "\n") controls spacing between different root table groups. For example, between [project] and [tool.ruff].
[tool.pyproject-fmt]
sub_table_spacing = "\n"  # Add blank line between sub-tables
separate_root_table = "\n"  # One blank line between root table groups (default)

Configuration priority

A priority system sets a global default while letting you override specific tables:

  1. collapse_tables - Highest priority, forces specific tables to collapse regardless of other settings
  2. expand_tables - Medium priority, forces specific tables to expand
  3. table_format - Lowest priority, sets the default for all tables not configured above

Set a broad default, then carve out exceptions per table. For example:

[tool.pyproject-fmt]
table_format = "short"  # Collapse most tables
expand_tables = ["project.entry-points"]  # But expand entry-points

Specificity rules

Table selectors follow CSS-like specificity rules: more specific selectors win over less specific ones. When determining whether to collapse or expand a table, the formatter checks from most specific to least specific until it finds a match.

For example, with this configuration:

[tool.pyproject-fmt]
table_format = "long"  # Expand all tables by default
collapse_tables = ["project"]  # Collapse project sub-tables
expand_tables = ["project.optional-dependencies"]  # But expand this specific one

The behavior will be:

  • project.urls → collapsed (matches project in collapse_tables)
  • project.scripts → collapsed (matches project in collapse_tables)
  • project.optional-dependencies → expanded (matches exactly in expand_tables, more specific than project)
  • tool.ruff.lint → expanded (no match in collapse/expand, uses table_format default)

This allows you to set broad rules for parent tables while making exceptions for specific sub-tables. The specificity check walks up the table hierarchy: for project.optional-dependencies, it first checks if project.optional-dependencies is in collapse_tables or expand_tables, then checks project, then falls back to the table_format default.

Supported tables

The following sub-tables can be formatted with this configuration:

Project tables:

  • project.urls - Project URLs (homepage, repository, documentation, changelog)
  • project.scripts - Console script entry points
  • project.gui-scripts - GUI script entry points
  • project.entry-points - Custom entry point groups
  • project.optional-dependencies - Optional dependency groups

Tool tables:

  • tool.ruff.format - Ruff formatter settings
  • tool.ruff.lint - Ruff linter settings
  • Any other tool sub-tables

Array of tables:

  • project.authors - Can be inline tables or [[project.authors]]
  • project.maintainers - Can be inline tables or [[project.maintainers]]
  • Any [[table]] entries throughout the file

Array of tables ([[table]]) are automatically collapsed to inline arrays when each inline table fits within the configured column_width. For example:

# Before
[[tool.commitizen.customize.questions]]
type = "list"

[[tool.commitizen.customize.questions]]
type = "input"

# After (with table_format = "short")
[tool.commitizen]
customize.questions = [{ type = "list" }, { type = "input" }]

If any inline table exceeds column_width, the array of tables remains in [[...]] format to maintain readability and TOML 1.0.0 compatibility (inline tables cannot span multiple lines).

String wrapping

By default the formatter wraps strings past the column width using line continuations. Some strings, regex patterns especially, break when wrapped, so exclude their keys with skip_wrap_for_keys:

[tool.pyproject-fmt]
skip_wrap_for_keys = ["*.parse", "*.regex", "tool.bumpversion.*"]

Pattern matching

The skip_wrap_for_keys option supports glob-like patterns:

  • Exact match: tool.bumpversion.parse matches only that specific key
  • Wildcard suffix: *.parse matches any key ending with .parse (e.g., tool.bumpversion.parse, project.parse)
  • Wildcard prefix: tool.bumpversion.* matches any key under tool.bumpversion (e.g., tool.bumpversion.parse, tool.bumpversion.serialize)
  • Global wildcard: * skips wrapping for all strings

Examples: ["*.parse", "*.regex"] to preserve regex fields, ["tool.bumpversion.*"] for a specific tool section, or ["*"] to skip all string wrapping.

pyproject-fmt is an opinionated formatter, much like black is for Python code. It keeps configuration minimal so every pyproject.toml lands on one standard format. That buys you:

  • less time configuring tools
  • smaller diffs when committing changes
  • code reviews where formatting never comes up

A few options exist (column_width, indent, table_format, sub_table_spacing, separate_root_table), but there are no dozens of toggles. column_width controls when arrays split across lines and when string values wrap with line continuations.

General Formatting

These rules apply uniformly across the entire pyproject.toml file.

Table Ordering

Tables are reordered into a consistent structure:

  1. [build-system]
  2. [project]
  3. [dependency-groups]
  4. [tool.*] sections in the order:
    1. Build backends: poetry, poetry-dynamic-versioning, pdm, setuptools, distutils, setuptools_scm, hatch, flit, scikit-build, meson-python, maturin, pixi, whey, py-build-cmake, sphinx-theme-builder, uv
    2. Builders: cibuildwheel, nuitka
    3. Linters/formatters: autopep8, black, yapf, djlint, ruff, isort, flake8, pycln, nbqa, pylint, repo-review, codespell, docformatter, pydoclint, interrogate, tomlsort, check-manifest, check-sdist, check-wheel-contents, deptry, vulture, pyproject-fmt, typos, bandit
    4. Type checkers: mypy, pyrefly, pyright, ty, django-stubs
    5. Testing: pytest, pytest_env, pytest-enabler, coverage
    6. Task runners: doit, spin, tox
    7. Release tools: bumpversion, commitizen, jupyter-releaser, semantic_release, tbump, towncrier, vendoring
    8. Any other tool.* in alphabetical order
  5. Any other tables (alphabetically)

String Quotes

All strings use double quotes by default. Single quotes are only used when the value contains double quotes:

# Before
name = 'my-package'
description = "He said \"hello\""

# After
name = "my-package"
description = 'He said "hello"'

Key Quotes

TOML keys are normalized to the simplest valid form. Keys that are valid bare keys (containing only A-Za-z0-9_-) have redundant quotes stripped. Single-quoted (literal) keys that require quoting are converted to double-quoted (basic) strings with proper escaping. This applies to all keys: table headers, key-value pairs, and inline table keys:

# Before
[tool."ruff"]
"line-length" = 120
lint.per-file-ignores.'tests/*' = ["S101"]

# After
[tool.ruff]
line-length = 120
lint.per-file-ignores."tests/*" = [ "S101" ]

Backslashes and double quotes within literal keys are escaped during conversion:

# Before
lint.per-file-ignores.'path\to\file' = ["E501"]

# After
lint.per-file-ignores."path\\to\\file" = [ "E501" ]

Array Formatting

Arrays are formatted based on line length, trailing comma presence, and comments. Short arrays stay on one line:

# Before
keywords = ["python", "toml"]

# After
keywords = [ "python", "toml" ]

Arrays that exceed column_width are expanded and get a trailing comma (shown here with a small column_width to keep the example short):

# Before
[project]
keywords = ["web", "toml", "pyproject", "formatting"]

# After
[project]
keywords = [
  "formatting",
  "pyproject",
  "toml",
  "web",
]

A trailing comma forces the multiline format, even for an array that would otherwise fit on one line:

# Before
classifiers = ["Development Status :: 4 - Beta",]

# After
classifiers = [
  "Development Status :: 4 - Beta",
]

A comment on an entry also forces the multiline format. Here ["E501", "E701"] would fit on one line, but the comment keeps it expanded:

lint.ignore = [
  "E501", # too long
  "E701",
]

Multiline formatting rules:

An array becomes multiline when any of these conditions are met:

  1. Trailing comma present - A trailing comma signals intent to keep multiline format
  2. Exceeds column width - Arrays longer than column_width are expanded (and get a trailing comma added)
  3. Contains comments - Arrays with inline or leading comments are always multiline

String Wrapping

Strings that exceed column_width (including the key name and " = " prefix) are wrapped into multi-line triple-quoted strings using line continuations (shown here with a small column_width):

# Before
description = "Format your pyproject.toml file in place"

# After
description = """\
  Format your pyproject.toml file in \
  place\
  """

Wrapping prefers breaking at spaces and at " :: " separators (common in Python classifiers). Strings inside inline tables are never wrapped. Strings that contain actual newlines are preserved as multi-line strings without adding line continuations. Use skip_wrap_for_keys to prevent wrapping for specific keys.

Table Formatting

Sub-tables can be formatted in two styles controlled by table_format:

Short format (collapsed to dotted keys):

[project]
urls.homepage = "https://example.com"
urls.repository = "https://github.com/example/project"

Long format (expanded to table headers):

[project.urls]
homepage = "https://example.com"
repository = "https://github.com/example/project"

Expanded sub-tables keep the order their dotted keys would have: a table's key order (see the per-table sections below) ranks its sub-tables, and sub-tables it does not list follow alphabetically. So [tool.coverage.run] comes before [tool.coverage.report] in the long format just as run.* keys precede report.* keys in the short one:

# Before
[tool.coverage.report]
skip_covered = true

[tool.coverage.run]
branch = true

# After
[tool.coverage.run]
branch = true
[tool.coverage.report]
skip_covered = true

Table spacing:

By default, different table groups (e.g. [project] and [tool.ruff]) are separated by a blank line, while sub-tables within the same group (e.g. [tool.ruff] and [tool.ruff.lint]) are kept compact with no blank line between them. You can control this with sub_table_spacing and separate_root_table. Each option takes a string of \n characters where each \n adds one blank line. For example, setting sub_table_spacing = "\n" adds a blank line between sub-tables:

# Before
[tool.ruff]
line-length = 120

[tool.ruff.lint]
select = ["E", "W"]

# After
[tool.ruff]
line-length = 120

[tool.ruff.lint]
select = [ "E", "W" ]

Comment Preservation

All comments are preserved during formatting:

  • Inline comments - Comments after a value on the same line stay with that value
  • Leading comments - Comments on the line before an entry stay with the entry below
  • Block comments - Multi-line comment blocks are preserved

Inline comment alignment:

Inline comments within arrays are aligned independently per array, based on that array's longest value:

# Before
lint.ignore = [
  "COM812", # Conflict with formatter
  "CPY", # No copyright statements
  "ISC001",   # Another rule
]

# After
lint.ignore = [
  "COM812", # Conflict with formatter
  "CPY",    # No copyright statements
  "ISC001", # Another rule
]

Disabled Keys

A commented-out line whose body is itself a single valid key-value (for example # default = true) is treated as a temporarily disabled field rather than free text. The formatter enables it for the duration of the pass, so it is laid out and ordered together with the table it belongs to, then comments it out again on the way out. This keeps a disabled key anchored to its entry instead of drifting to the next table, and formats the line the same way the enabled key would be:

# Before
[[tool.uv.index]]
name = "pypi"
authenticate = "never"
# default = true
# ignore-error-codes = [400,401,403]

# After
[[tool.uv.index]]
name = "pypi"
authenticate = "never"
# default = true
# ignore-error-codes = [ 400, 401, 403 ]

Comments that are not a single valid key-value (prose, multi-line blocks, commented-out table headers like # [tool.x]) are left untouched and follow the usual comment-preservation rules above. The heuristic is purely structural, so a prose comment that happens to be valid TOML (such as a key = value example written in documentation) is reflowed too; if that matters, phrase the comment so it does not parse as a key-value. Keys that would not fit on a single line within column_width are left as plain comments.

Group Markers

By default the formatter reorders each array, table, and section list as a single unit, so any entry can move to its sorted position. Mark a boundary with a standalone comment that starts with # Group:: the formatter then sorts within each group, holds the groups in their original order, and keeps the marker at the top of its group. Reach for this when related entries belong together but should still be sorted.

Files without a # Group: marker format the same as before, so the feature stays opt-in. Case does not matter, so # group: works too. Only standalone comment lines count; the formatter ignores inline trailing comments.

The formatter sorts the entries inside each group:

# Before
[project]
dependencies = [
  # Group: web
  "flask",
  "django",
  # Group: db
  "sqlalchemy",
  "psycopg2",
]

# After
[project]
dependencies = [
  # Group: web
  "django",
  "flask",
  # Group: db
  "psycopg2",
  "sqlalchemy",
]

A # Group: marker works the same way before a key in a table or before a [tool.*] header: the formatter sorts the keys or sections up to the next marker, and never moves them across the boundary.

Table-Specific Handling

Beyond general formatting, each table has specific key ordering and value normalization rules.

[build-system]

The PEP 517 / PEP 518 table that declares how your project is built. See the packaging specification.

Keys are ordered build-backend → requires → backend-path, and requires is normalized and sorted. A redundant wheel requirement is removed when the build backend is setuptools.

Key ordering: build-backend → requires → backend-path

Value normalization:

  • requires: dependencies normalized per PEP 508 and sorted alphabetically by package name
  • backend-path: entries sorted alphabetically

Redundant wheel removal:

A bare wheel entry is removed from requires when build-backend is setuptools.build_meta or setuptools.build_meta:__legacy__: setuptools either injects wheel dynamically when building (before version 70.1) or bundles its own copy of bdist_wheel (70.1 and later), so listing it has no effect. The entry is kept when it carries a version constraint, extras, or markers (it then expresses intent the backend's dynamic injection would honor), when backend-path is set (an in-tree backend may import wheel directly), or when setuptools itself is missing from requires.

# Before
[build-system]
requires = ["setuptools >= 45", "wheel"]
build-backend = "setuptools.build_meta"

# After
[build-system]
build-backend = "setuptools.build_meta"
requires = [ "setuptools>=45" ]

[project]

The PEP 621 core metadata table. See the packaging specification.

Keys follow the canonical metadata order; name, dependencies, classifiers, and keywords are normalized and sorted; version is validated.

Key ordering: name → version → import-names → import-namespaces → description → readme → keywords → license → license-files → maintainers → authors → requires-python → classifiers → dynamic → dependencies → optional-dependencies → urls → scripts → gui-scripts → entry-points

Field normalizations:

name
Converted to canonical format (lowercase with hyphens): My_Package → my-package
version
Kept verbatim, because it is the exact version published in the package metadata — normalizing would rewrite e.g. CalVer 2026.08.10 to 2026.8.10. A value that is not a valid PEP 440 version is rejected: the formatter reports it on standard error, leaves the file untouched, and exits with a non-zero status.
description
Whitespace normalized: multiple spaces collapsed, consistent spacing after periods.
license
License expression operators (and, or, with) uppercased: MIT or Apache-2.0 → MIT OR Apache-2.0
requires-python
Whitespace removed: >= 3.9 → >=3.9
keywords
Deduplicated (case-insensitive) and sorted alphabetically.
dynamic
Sorted alphabetically.
import-names / import-namespaces
Semicolon spacing normalized (foo;bar → foo; bar), entries sorted alphabetically.
classifiers
Deduplicated and sorted alphabetically.
authors / maintainers
Sorted by name, then email. Keys within each entry ordered: name → email.

Dependency normalization: every dependency array (dependencies, optional-dependencies.*) is normalized per PEP 508 (spaces removed, redundant .0 suffixes stripped unless keep_full_version = true) and sorted alphabetically by canonical package name:

# Before
[project]
dependencies = ["requests >= 2.0.0", "click~=8.0"]

# After
[project]
dependencies = [ "click~=8.0", "requests>=2" ]

A direct-reference dependency keeps a space before its marker separator, because PEP 508 only ends the URL at whitespace; without it, installers read the ; and the marker as part of the URL and reject the entry:

# Before
[project]
dependencies = ["pkg @ git+https://github.com/user/repo.git@main; python_version>='3.10'"]

# After
[project]
dependencies = [ "pkg @ git+https://github.com/user/repo.git@main ; python_version>='3.10'" ]

Optional-dependency extra names are normalized to lowercase with hyphens:

# Before
[project.optional-dependencies]
Dev_Tools = ["pytest"]

# After
[project]
optional-dependencies.dev-tools = [ "pytest" ]

Python version classifiers are generated automatically from requires-python and max_supported_python (here 3.14). Disable with generate_python_version_classifiers = false:

# Before
[project]
requires-python = ">=3.10"

# After
[project]
requires-python = ">=3.10"
classifiers = [
  "Programming Language :: Python :: 3 :: Only",
  "Programming Language :: Python :: 3.10",
  "Programming Language :: Python :: 3.11",
  "Programming Language :: Python :: 3.12",
  "Programming Language :: Python :: 3.13",
  "Programming Language :: Python :: 3.14",
]

Entry points: inline tables within entry-points are expanded to dotted keys:

# Before
[project]
entry-points.console_scripts = { mycli = "mypackage:main" }

# After
[project]
entry-points.console_scripts.mycli = "mypackage:main"

Authors / maintainers can be inline tables (short format):

# Before
[project]
authors = [{ name = "Alice", email = "alice@example.com" }]

# After
[project]
authors = [ { name = "Alice", email = "alice@example.com" } ]

or an expanded array of tables (long format, controlled by table_format, expand_tables, and collapse_tables):

[[project.authors]]
name = "Alice"
email = "alice@example.com"

[dependency-groups]

The PEP 735 table for named groups of development dependencies. See the packaging specification.

Groups are ordered dev → test → type → docs → others alphabetically; each group is normalized and sorted.

Key ordering: dev → test → type → docs → others alphabetically

Value normalization:

  • all dependencies normalized per PEP 508
  • sorted with regular dependencies first, then include-group entries
# Before
[dependency-groups]
dev = [{ include-group = "test" }, "ruff>=0.4", "mypy>=1"]

# After
[dependency-groups]
dev = [ "mypy>=1", "ruff>=0.4", { include-group = "test" } ]

[tool.poetry]

Poetry is a Python dependency management and packaging tool. See its pyproject.toml reference.

Covers both Poetry 1.x (legacy metadata under [tool.poetry]) and Poetry 2.x (metadata moved to [project], Poetry-specific keys still here). Metadata is ordered by section, Poetry-specific inline tables get canonical key order, and set-semantic arrays are sorted while order-significant ones are preserved.

Top-level key ordering:

  1. Identity: name → version → description → package-mode
  2. License & authorship: license → authors → maintainers
  3. Documentation: readme → homepage → repository → documentation
  4. Discovery: keywords → classifiers
  5. Packaging contents: packages → include → exclude → build
  6. Dependencies (sub-tables): dependencies → dev-dependencies → group → extras
  7. Entry points / distribution: scripts → plugins → urls → source
  8. Poetry runtime constraints: requires-poetry → requires-plugins → build-constraints

Sub-table key ordering:

[tool.poetry.dependencies] / [tool.poetry.dev-dependencies] / per-group dependencies
python first (interpreter constraint), all other package names alphabetized.
[tool.poetry.group.<name>]
optional → include-groups → dependencies.
[tool.poetry.extras], [tool.poetry.scripts], [tool.poetry.urls], [tool.poetry.plugins.*], [tool.poetry.requires-plugins], [tool.poetry.build-constraints]
Keys alphabetized.
[tool.poetry.build]
script → generate-setup-file.
[[tool.poetry.source]]
Each entry's keys ordered name → url → priority → links → indexed, with the deprecated default and secondary keys placed last. Array order itself is preserved (priority ordering is semantically significant).

Sorted arrays:

  • keywords, classifiers: deduplicated (case-insensitive) and sorted alphabetically.
  • exclude: sorted alphabetically.
  • [tool.poetry.extras] values (each extras.<name>): sorted alphabetically.
  • [tool.poetry.group.<name>.include-groups]: sorted alphabetically.
  • Per-dependency extras arrays (in dependencies, dev-dependencies, per-group dependencies, requires-plugins, build-constraints): sorted alphabetically.

Preserved as written (order is semantically significant): authors, maintainers, packages, include, readme (when an array), multi-constraint dependency arrays, and [[tool.poetry.source]] entries.

Inline-table key ordering: when a Poetry-specific inline table is detected (via discriminator keys unique to Poetry's schema), its keys are reordered:

  • Sources ({ priority = ... }, { secondary = ... }, { links = ... }, { indexed = ... }): name → url → priority → links → indexed → default → secondary.
  • Git dependencies ({ git = ... }): git → branch → tag → rev → subdirectory → python → platform → markers → allow-prereleases → allows-prereleases → optional → extras → develop.
  • Path dependencies ({ path = ... }): path → develop → subdirectory → python → platform → markers → optional → extras.
  • File dependencies ({ file = ... }): file → subdirectory → python → platform → markers → optional → extras.

Inline tables that don't match any Poetry-specific schema (for example [[project.authors]] inline form { name = "...", email = "..." }) are left untouched.

# Before
[[tool.poetry.source]]
priority = "primary"
url = "https://example.com"
name = "private"

[tool.poetry.dependencies]
zebra = "^1.0"
python = "^3.11"
foo = { branch = "main", git = "https://example.com/foo" }

# After
[tool.poetry]
dependencies.python = "^3.11"
dependencies.foo = { git = "https://example.com/foo", branch = "main" }
dependencies.zebra = "^1.0"
source = [ { name = "private", url = "https://example.com", priority = "primary" } ]

[tool.pdm.*]

PDM is a modern Python package and dependency manager. See its build configuration reference.

Top-level keys are ordered distribution → resolution → version → build → scripts → source → dev-dependencies → publish → options; name and glob arrays are sorted, while source-entry order is preserved.

Top-level key ordering: distribution / package-type / plugins → resolution → version → build → scripts → source → dev-dependencies → publish → options.

Sub-table ordering (collapsed to dotted keys):

  • version: source → path → getter → write_to → write_template → tag_regex → tag_filter → fallback_version → version_format.
  • build: includes → excludes → source-includes → package-dir → is-purelib → run-setuptools → custom-hook → editable-backend.
  • [[tool.pdm.source]] (array of tables, order preserved): per-entry name → url → type → verify_ssl → include_packages → exclude_packages.

Sorted arrays: plugins, build.includes, build.excludes, build.source-includes, resolution.excludes, every dev-dependencies.<group> value array, and include_packages / exclude_packages inside source entries.

[tool.setuptools] and [tool.setuptools_scm]

setuptools is a long-standing build backend and packaging library; setuptools_scm derives the package version from SCM tags. See the setuptools pyproject.toml reference and the setuptools_scm configuration reference.

Keys in both tables are grouped (discovery → data → metadata → deprecated); name and glob arrays are sorted, while literal lists like packages are preserved.

[tool.setuptools] top-level key ordering (grouped):

  1. Packaging discovery: py-modules → packages.find.* / packages.find-namespace.* → packages → package-dir
  2. Package data: include-package-data → package-data → exclude-package-data
  3. Dynamic metadata: dynamic
  4. Extensions / build customization: ext-modules → cmdclass
  5. Distribution metadata: platforms → provides → obsoletes → license-files
  6. Data files: data-files
  7. Deprecated / obsolete (pushed last): script-files → namespace-packages → zip-safe → eager-resources → dependency-links

[tool.setuptools.packages.find] / [tool.setuptools.packages.find-namespace] inner ordering: where → include → exclude → namespaces.

[tool.setuptools.package-data] / [tool.setuptools.exclude-package-data] / [tool.setuptools.data-files] ordering: the catch-all "*" pattern always goes first, then the other package patterns alphabetically; each value (an array of glob patterns) is sorted alphabetically.

[tool.setuptools.dynamic] ordering: field names alphabetized. Inline-table directives (e.g. version = { attr = "pkg.__version__" } or readme = { file = "README.md", content-type = "text/markdown" }) get their keys ordered attr → file → content-type.

Sorted arrays:

  • py-modules, platforms, provides, obsoletes, script-files, namespace-packages, eager-resources: alphabetized.
  • packages.find.include / packages.find.exclude / packages.find-namespace.*: alphabetized.
  • Values inside package-data / exclude-package-data / data-files tables: alphabetized.

Preserved as written (order is meaningful): packages (literal list, first match wins), license-files (PEP 639 concatenation order), and everything under [[tool.setuptools.ext-modules]] (compiler and linker argv arrays).

[tool.setuptools_scm] key ordering (grouped):

  1. Version output: version_file → version_file_template
  2. Version computation: version_scheme → local_scheme → version_cls → normalize
  3. Root discovery: root → relative_to → fallback_root → parent → search_parent_directories → dist_name
  4. Tag / parse: tag_regex → parse → parentdir_prefix_version → fallback_version
  5. Nested SCM-specific tables: scm.git.pre_parse → scm.git.describe_command
  6. Deprecated (pushed last): git_describe_command (use scm.git.describe_command) → write_to (use version_file) → write_to_template (use version_file_template) → version_class (use version_cls) → template
# Before
[tool.setuptools]
zip-safe = false
py-modules = ["foo", "bar"]
packages = ["my_pkg"]

[tool.setuptools.packages.find]
namespaces = true
where = ["src"]
include = ["my_pkg*"]

[tool.setuptools.dynamic]
readme = { content-type = "text/markdown", file = "README.md" }

# After
[tool.setuptools]
py-modules = [ "bar", "foo" ]
packages.find.where = [ "src" ]
packages.find.include = [ "my_pkg*" ]
packages.find.namespaces = true
packages = [ "my_pkg" ]
dynamic.readme = { file = "README.md", content-type = "text/markdown" }
zip-safe = false

[tool.hatch.*]

Hatch is a modern, extensible Python project manager built around the Hatchling build backend. See its build configuration reference.

Keys across the many [tool.hatch.*] sub-tables are grouped (version → metadata → build → publish → workspace → environments); name and path arrays are sorted, while build-hook and matrix order are preserved.

Key ordering: keys at [tool.hatch] level (after collapse, dotted version.* / build.* / metadata.* / envs.* / publish.* / workspace.*):

  1. Version: version.source → version.path → version.pattern → version.expression → version.scheme → version.validate-bump → version.fallback-version → version.raw-options.
  2. Metadata: metadata.allow-direct-references → metadata.allow-ambiguous-features → metadata.hooks.
  3. Build: build.dev-mode-dirs → build.directory → build.sources → build.packages → build.include → build.exclude → build.force-include → build.artifacts → build.ignore-vcs → build.skip-excluded-dirs → build.reproducible → build.hooks → wheel target (packages, include, exclude, force-include, artifacts, hooks, shared-data, extra-metadata, etc.) → sdist target (include, exclude, force-include, support-legacy, strict-naming).
  4. Publish: publish.index.disable → publish.index.repos → publish.index.
  5. Workspace: workspace.members → workspace.exclude.
  6. Environments (envs.<name>.*): each environment's keys follow type → template → detached → description → platforms → python → path → installer → skip-install → system-packages → dev-mode → features → dependencies → extra-dependencies → extra-args → pre-install-commands → post-install-commands → env-include → env-exclude → env-vars → scripts → matrix → matrix-name-format → overrides.

Sorted arrays:

  • Build: include, exclude, force-include, artifacts, packages, sources, dev-mode-dirs, and the matching build.targets.wheel.* / build.targets.sdist.* arrays.
  • Environments: per-env dependencies, extra-dependencies, features, platforms, env-include, env-exclude, pre-install-commands, post-install-commands.
  • Workspace: members, exclude.

scripts and env-vars sub-tables under each environment have their inner keys alphabetized.

Preserved as written: build-hook order and matrix entry order (both carry semantic meaning).

[tool.scikit-build]

scikit-build-core is a CMake-based build backend for Python C/C++ extensions. See its configuration reference.

Keys are ordered meta → build → cmake → ninja → sdist → wheel → install → editable → logging → metadata → search → generate → overrides; name and path lists are sorted, while cmake/ninja argv are preserved.

Key ordering: meta keys (minimum-version, build-dir, fail, experimental, strict-config) → build → cmake → ninja → sdist → wheel → install → editable → logging / messages → metadata → search → generate (array of tables) → overrides (array of tables).

Sorted arrays: include, exclude, packages, files, targets, components, exclude-fields.

Preserved as written: args and define (CLI argv for cmake/ninja).

[tool.maturin]

Maturin builds and publishes Rust-based Python extension modules. See its configuration reference.

Keys are ordered module identity → source layout → cargo settings → compatibility/strip → behavior; set-semantic arrays are sorted, while cargo/rustc argv are preserved.

Key ordering: module identity (module-name, bindings, python-source, python-packages, python-bin-path) → source layout (src, manifest-path, include, exclude, sdist-include, sdist-generator, data) → cargo settings (features, no-default-features, all-features, cargo-extra-args, rustc-extra-args, config, profile, target, target-dir) → compatibility / strip (compatibility, auditwheel, skip-auditwheel, strip, frozen, locked, offline, zig) → behavior (use-cross).

Sorted arrays: python-packages, include, exclude, sdist-include, features (all set semantics).

Preserved as written: cargo-extra-args / rustc-extra-args (CLI argv).

[tool.pixi]

Pixi is a cross-platform conda/PyPI package and environment manager. See its pyproject.toml reference.

Keys are grouped by function (workspace metadata → configuration → dependencies → environments → build); channel and platform arrays are sorted.

Key ordering:

  1. Workspace metadata: workspace.name → workspace.version → workspace.description → workspace.authors → workspace.license → workspace.license-file → workspace.readme → workspace.homepage → workspace.repository → workspace.documentation
  2. Workspace configuration: workspace.channels → workspace.platforms → workspace.channel-priority → workspace.solve-strategy → workspace.conda-pypi-map → workspace.requires-pixi → workspace.exclude-newer → workspace.preview → workspace.build-variants → workspace.build-variants-files
  3. Dependencies: dependencies → host-dependencies → build-dependencies → run-dependencies → constraints → pypi-dependencies → pypi-options
  4. Development: dev
  5. Environment setup: system-requirements → activation → tasks
  6. Targeting: target → feature → environments
  7. Package build: package

Sorted arrays: workspace.channels, workspace.platforms, workspace.preview, workspace.build-variants-files.

[tool.uv]

uv is a fast Python package and project manager from Astral. See its settings reference.

Keys are grouped by function (Python → dependencies → sources → resolution → build → network → publishing → workspace); package-name arrays and the sources table are sorted alphabetically.

Key ordering:

  1. Version & Python: required-version → python-preference → python-downloads
  2. Dependencies: dev-dependencies → default-groups → dependency-groups → constraint-dependencies → override-dependencies → exclude-dependencies → dependency-metadata
  3. Sources & indexes: sources → index → index-url → extra-index-url → find-links → no-index → index-strategy → keyring-provider
  4. Package handling: no-binary* → no-build* → no-sources* → reinstall* → upgrade*
  5. Resolution: resolution → prerelease → fork-strategy → environments → required-environments → exclude-newer*
  6. Build & Install: compile-bytecode → link-mode → config-settings* → extra-build-* → concurrent-builds → concurrent-downloads → concurrent-installs
  7. Network & Security: allow-insecure-host → native-tls → offline → no-cache → cache-dir → http-proxy → https-proxy → no-proxy
  8. Publishing: publish-url → check-url → trusted-publishing
  9. Python management: python-install-mirror → pypy-install-mirror → python-downloads-json-url
  10. Workspace & Project: managed → package → workspace → conflicts → cache-keys → build-backend
  11. Other: pip → preview → torch-backend

Sorted arrays:

Package-name arrays
constraint-dependencies, override-dependencies, dev-dependencies, exclude-dependencies, no-binary-package, no-build-package, no-build-isolation-package, no-sources-package, reinstall-package, upgrade-package
Other arrays
environments, required-environments, allow-insecure-host, no-proxy, workspace.members, workspace.exclude

Sources table: sources entries are sorted alphabetically by package name:

# Before
[tool.uv.sources]
zebra = { git = "..." }
alpha = { path = "..." }

# After
[tool.uv]
sources.alpha = { path = "..." }
sources.zebra = { git = "..." }

pip subsection: [tool.uv.pip] follows the same rules, with arrays like extra, no-binary-package, no-build-package, reinstall-package, and upgrade-package sorted alphabetically.

[tool.cibuildwheel]

cibuildwheel builds Python wheels across platforms in CI. See its options reference.

Keys are ordered selection → build config → build phases → test phases → platform images → per-platform sub-tables → overrides; set-semantic arrays are sorted, while argv-like lists are preserved.

Key ordering: selection (build, skip, test-skip, archs, enable, free-threaded-support) → build configuration (build-frontend, build-verbosity, config-settings, dependency-versions, environment, environment-pass) → build phases (before-all, before-build, repair-wheel-command) → test phases (before-test, test-command, test-requires, test-extras, test-groups, test-sources) → platform images (manylinux-*-image, musllinux-*-image) → container-engine → per-platform sub-tables (linux, macos, windows, android, ios, pyodide) → overrides last.

Per-platform sub-tables follow the same inner ordering. overrides entries, whether written as [[tool.cibuildwheel.overrides]] or as inline tables in overrides = [...], place select first (required), then the regular cibuildwheel keys; the array order itself is preserved (later overrides win).

Sorted arrays: enable, test-extras, test-groups.

Preserved as written: most other array-valued keys (test-requires, before-all, test-command, the various environment* fields) are CLI argv or ordered lists.

[tool.autopep8]

autopep8 automatically formats Python code to conform to PEP 8. See its configuration reference.

Keys are ordered length/indent → mode → rules → behavior; rule lists are sorted.

Key ordering: length/indent → mode (in-place, recursive, diff, list-fixes) → rules (ignore, select, exclude) → behavior.

Sorted arrays: ignore, select, exclude.

[tool.black]

Black is an opinionated Python code formatter. See its configuration reference.

Keys follow Black's option grouping; target-version and enable-unstable-feature arrays are alphabetized.

Key ordering:

  1. required-version → target-version → line-length
  2. File selection: include → extend-exclude → force-exclude → exclude
  3. Behavior: skip-string-normalization → skip-magic-trailing-comma → preview → unstable → enable-unstable-feature → fast → workers
  4. Output: color → verbose → quiet

Sorted arrays: target-version (so py39 precedes py310), enable-unstable-feature.

The include / exclude family are regex strings, not arrays, so they're left as-is.

[tool.yapf]

YAPF is a configurable Python code formatter from Google. See its configuration reference.

A single flat table: based_on_style comes first (it sets the defaults), then the rest in a fixed order.

Key ordering: based_on_style first (sets defaults), then column_limit, indent_width, continuation_indent_width, then the remaining keys alphabetized.

[tool.djlint]

djLint is a linter and formatter for HTML templates (Django, Jinja, and more). See its configuration reference.

Keys are ordered profile/scope → formatting → linting → ignores → output; exclude and block lists are sorted.

Key ordering: profile/scope → formatting → linting → ignores → output.

Sorted arrays: exclude, extend_exclude, custom_blocks, custom_html, ignore, ignore_blocks.

[tool.ruff]

Ruff is a fast Python linter and formatter written in Rust. See its settings reference.

Keys follow Ruff's option grouping (global → paths → behavior → output → format → lint); rule-code, path, and name arrays are sorted with natural ordering (RUF1 < RUF9 < RUF10).

Key ordering:

  1. Global settings: required-version → extend → target-version → line-length → indent-width → tab-size
  2. Path settings: builtins → namespace-packages → src → include → extend-include → exclude → extend-exclude → force-exclude → respect-gitignore
  3. Behavior flags: preview → fix → unsafe-fixes → fix-only → show-fixes → show-source
  4. Output settings: output-format → cache-dir
  5. format.* keys
  6. lint.* keys: select → extend-select → ignore → extend-ignore → per-file-ignores → fixable → unfixable → plugin configurations

Sorted arrays: alphabetical with natural ordering (RUF1 < RUF9 < RUF10); per-file-ignores values are sorted too:

# Before
[tool.ruff]
lint.select = ["F", "E", "RUF", "I"]
lint.ignore = ["E701", "E501"]
lint.per-file-ignores."tests/*.py" = ["S101", "D103"]

# After
[tool.ruff]
lint.select = [ "E", "F", "I", "RUF" ]
lint.ignore = [ "E501", "E701" ]
lint.per-file-ignores."tests/*.py" = [ "D103", "S101" ]

The full set of sorted array keys:

Top-level
exclude, extend-exclude, include, extend-include, builtins, namespace-packages, src
Format
format.exclude
Lint
select, extend-select, ignore, extend-ignore, fixable, extend-fixable, unfixable, extend-safe-fixes, extend-unsafe-fixes, external, task-tags, exclude, typing-modules, allowed-confusables, logger-objects
Per-file patterns
lint.per-file-ignores.*, lint.extend-per-file-ignores.*
Plugin arrays
lint.flake8-bandit.hardcoded-tmp-directory, lint.flake8-bandit.hardcoded-tmp-directory-extend, lint.flake8-boolean-trap.extend-allowed-calls, lint.flake8-bugbear.extend-immutable-calls, lint.flake8-builtins.builtins-ignorelist, lint.flake8-gettext.extend-function-names, lint.flake8-gettext.function-names, lint.flake8-import-conventions.banned-from, lint.flake8-pytest-style.raises-extend-require-match-for, lint.flake8-pytest-style.raises-require-match-for, lint.flake8-self.extend-ignore-names, lint.flake8-self.ignore-names, lint.flake8-tidy-imports.banned-module-level-imports, lint.flake8-type-checking.exempt-modules, lint.flake8-type-checking.runtime-evaluated-base-classes, lint.flake8-type-checking.runtime-evaluated-decorators, lint.isort.constants, lint.isort.default-section, lint.isort.extra-standard-library, lint.isort.forced-separate, lint.isort.no-lines-before, lint.isort.required-imports, lint.isort.single-line-exclusions, lint.isort.variables, lint.pep8-naming.classmethod-decorators, lint.pep8-naming.extend-ignore-names, lint.pep8-naming.ignore-names, lint.pep8-naming.staticmethod-decorators, lint.pydocstyle.ignore-decorators, lint.pydocstyle.property-decorators, lint.pyflakes.extend-generics, lint.pylint.allow-dunder-method-names, lint.pylint.allow-magic-value-types

[tool.isort]

isort sorts and organizes Python imports. See its configuration options.

profile comes first (it sets the defaults everything else overrides), then output style, known sources, separation, skip patterns, and import edits; name lists are sorted, while sequence-sensitive lists are preserved.

Key ordering:

  1. profile: sets defaults that the keys below override
  2. Output style: line, wrap, indent, and multi-line options
  3. Known sources: sections → default_section → known_standard_library → extra_standard_library → known_third_party → known_first_party → known_local_folder → known_other
  4. Forced separation, skip patterns, import add/remove, and section heading comments

Sorted arrays: known_standard_library, extra_standard_library, known_third_party, known_first_party, known_local_folder, known_other, namespace_packages, src_paths, skip, skip_glob, extend_skip, extend_skip_glob, supported_extensions, blocked_extensions, single_line_exclusions, forced_separate, treat_comments_as_code, treat_all_comments_as_code, constants, variables.

Preserved as written (sequence is significant): sections (output section order), no_lines_before, add_imports, remove_imports, required_imports, force_to_top.

[tool.pylint.*]

Pylint is a static analyzer and linter for Python. See its configuration reference.

Sub-tables follow Pylint's checker-group order; all rule, name, and path lists are sorted by leaf key name regardless of sub-table.

Sub-table order: main (and legacy alias master) → messages_control → reports → basic → format → design → classes → exceptions → imports → logging → method_args → refactoring → similarities → spelling → string → typecheck → variables → miscellaneous.

Sorted arrays: enable, disable, load-plugins, extension-pkg-allow-list, extension-pkg-whitelist, ignore, ignore-patterns, ignore-paths, ignored-modules, ignored-classes, ignored-argument-names, good-names, bad-names, logging-modules, valid-classmethod-first-arg, valid-metaclass-classmethod-first-arg, callbacks, additional-builtins, allowed-redefined-builtins, preferred-modules, deprecated-modules, known-third-party, known-standard-library, allowed-modules, expected-line-ending-format, overgeneral-exceptions, defining-attr-methods, exclude-protected. Matching is on the leaf key name regardless of which sub-table it appears in.

[tool.codespell]

codespell checks code and text for common misspellings. See its configuration reference.

Keys are ordered dictionaries → scope → fix behavior → output; word and path lists are sorted.

Key ordering: dictionaries (builtin, dictionary, ignore-words, ignore-words-list, ignore-regex, ignore-multiline-regex, exclude-file) → scope (skip, uri-ignore-words-list, check-filenames, check-hidden, hidden, regex, user-input) → fix behavior (write-changes, interactive, enable-colors, disable-colors) → output (count, quiet-level, summary).

Sorted arrays: builtin, dictionary, skip, ignore-words-list, uri-ignore-words-list.

[tool.docformatter]

docformatter formats Python docstrings to follow PEP 257. See its configuration reference.

Keys are ordered behavior → format width → wrap/summary tweaks → other.

Key ordering: behavior (in-place, recursive, check, diff, black, pep257, non-strict) → format width (line-length, wrap-summaries, wrap-descriptions, tab-width) → wrap/summary tweaks → other.

[tool.interrogate]

interrogate measures docstring coverage of a Python codebase. See its configuration reference.

Keys are ordered threshold → ignore flags → exclude → output; exclude and regex lists are sorted.

Key ordering: threshold → ignore flags → exclude → output.

Sorted arrays: exclude, extend-exclude, ignore-regex.

[tool.check-manifest]

check-manifest checks that MANIFEST.in is complete for an sdist. See its configuration reference.

Keys are ordered ignore → ignore-bad-ideas → ignore-default-rules; both glob lists are sorted.

Key ordering: ignore → ignore-bad-ideas → ignore-default-rules.

Sorted arrays: ignore and ignore-bad-ideas (file-glob lists).

[tool.deptry]

deptry finds unused, missing, and transitive dependencies in Python projects. See its usage reference.

Keys are ordered scope/exclude → ignore rules → per-rule ignores → behavior → mapping; the ignore and path lists are sorted.

Key ordering: scope/exclude → ignore rules → per-rule ignores → behavior → mapping.

Sorted arrays: the ignore_* / exclude / requirements_files / pep621_dev_dependency_groups / known_first_party lists.

[tool.vulture]

Vulture finds unused (dead) Python code. See its configuration reference.

Keys are ordered paths → ignore → behavior → output; path and name lists are sorted.

Key ordering: paths → ignore (exclude, ignore_names, ignore_decorators) → behavior (make_whitelist, min_confidence, sort_by_size) → output (verbose).

Sorted arrays: paths, exclude, ignore_names, ignore_decorators.

[tool.bandit]

Bandit finds common security issues in Python code. See its configuration reference.

Keys are ordered exclude_dirs → targets → tests → skips → per-plugin sub-tables; all array values are alphabetized.

Key ordering: exclude_dirs → targets → tests → skips → per-plugin sub-tables (assert_used, hardcoded_tmp_directory, etc.).

Sorted arrays: all array values (rule IDs, directory paths, function-name lists, all set semantics).

[tool.mypy]

mypy is a static type checker for Python. See its configuration reference.

Covers all documented mypy options plus the [[tool.mypy.overrides]] array of tables, reordered to match mypy's configuration reference; set-semantic arrays are sorted, while plugins and mypy_path are preserved.

Top-level key ordering (sectioned):

  1. Import discovery: mypy_path → files → modules → packages → exclude → exclude_gitignore → namespace_packages → explicit_package_bases → ignore_missing_imports → follow_untyped_imports → follow_imports → follow_imports_for_stubs → python_executable → no_site_packages → no_silence_site_packages
  2. Platform configuration: python_version → platform → always_true → always_false
  3. Disallow dynamic typing: disallow_any_unimported → disallow_any_expr → disallow_any_decorated → disallow_any_explicit → disallow_any_generics → disallow_subclassing_any
  4. Untyped definitions and calls: disallow_untyped_calls → untyped_calls_exclude → disallow_untyped_defs → disallow_incomplete_defs → check_untyped_defs → disallow_untyped_decorators
  5. None and Optional: implicit_optional → strict_optional
  6. Configuring warnings: warn_redundant_casts → warn_unused_ignores → warn_no_return → warn_return_any → warn_unreachable → deprecated_calls_exclude
  7. Suppressing errors: ignore_errors
  8. Miscellaneous strictness: allow_untyped_globals → allow_redefinition → local_partial_types → disable_error_code → enable_error_code → extra_checks → implicit_reexport → strict_equality → strict_bytes → strict
  9. Configuring error messages: show_error_context → show_column_numbers → show_error_end → hide_error_codes → show_error_code_links → pretty → color_output → error_summary → show_absolute_path
  10. Incremental mode: incremental → cache_dir → sqlite_cache → cache_fine_grained → skip_version_check → skip_cache_mtime_checks
  11. Advanced options: plugins → pdb → show_traceback → raise_exceptions → custom_typing_module → custom_typeshed_dir → warn_incomplete_stub → native_parser
  12. Report generation: any_exprs_report → cobertura_xml_report → html_report → linecount_report → linecoverage_report → lineprecision_report → txt_report → xml_report → xslt_html_report → xslt_txt_report
  13. Miscellaneous: junit_xml → junit_format → scripts_are_modules → warn_unused_configs → verbosity
  14. overrides last.

Overrides entry key ordering: in each [[tool.mypy.overrides]] entry, module comes first (required), then per-module overridable keys in the same logical grouping as the parent table (import behavior, platform markers, disallow dynamic typing, untyped defs/calls, optional handling, warnings, suppression, miscellaneous strictness).

Sorted arrays:

  • Top-level: files, modules, packages, exclude, always_true, always_false, untyped_calls_exclude, deprecated_calls_exclude, disable_error_code, enable_error_code.
  • Inside overrides entries: module (when an array of patterns), always_true, always_false, disable_error_code, enable_error_code.

Preserved as written: plugins (run in declared order; reordering changes behavior) and mypy_path (a search path with priority semantics).

Inline-table handling: when [[tool.mypy.overrides]] collapses to overrides = [{...}, {...}] under the default table_format = "short", key order inside each entry is normalized via discriminators unique to mypy (disable_error_code / enable_error_code / ignore_missing_imports / follow_untyped_imports / ignore_errors / warn_unused_ignores / disallow_untyped_defs / check_untyped_defs). The arrays inside each inline entry are sorted in place, so disable_error_code = [...] is alphabetized whether the override is expanded or collapsed.

# Before
[[tool.mypy.overrides]]
disable_error_code = ["import-untyped", "attr-defined"]
module = "pkg.*"

# After
[tool.mypy]
overrides = [ { module = "pkg.*", disable_error_code = [ "attr-defined", "import-untyped" ] } ]

[tool.pyrefly]

Pyrefly is Meta's fast Python type checker and language server, written in Rust. See its configuration reference.

Keys follow a fixed platform → paths → behavior → errors order; path arrays are sorted.

Key ordering: python_version → python_platform → python_interpreter → project_includes → project_excludes → search_path → site_package_path → use_untyped_imports → replace_imports_with_any → ignore_errors_in_generated_code → errors.

Sorted arrays: the path arrays.

[tool.pyright] and [tool.basedpyright]

Pyright is Microsoft's fast Python type checker; basedpyright is a community fork sharing the same schema. See the pyright configuration reference and the basedpyright config-files reference.

Keys are ordered platform → mode flags → paths → strict-flavor toggles → defineConstant → report* rules (alphabetized) → executionEnvironments; path arrays are sorted.

Key ordering:

  1. Platform / interpreter: pythonVersion → pythonPlatform → pythonPath → venv → venvPath → typeshedPath → stubPath
  2. Mode flags: typeCheckingMode → strict → failOnWarnings → useLibraryCodeForTypes
  3. Paths: include → exclude → ignore → extraPaths
  4. Strict-flavor toggles: strictListInference, strictDictionaryInference, strictSetInference, strictParameterNoneValue, enableExperimentalFeatures, enableTypeIgnoreComments, analyzeUnannotatedFunctions, disableBytesTypePromotions, deprecateTypingAliases
  5. defineConstant
  6. All report* rules, alphabetized
  7. executionEnvironments (last)

The report* rules (70+ in pyright; basedpyright adds more) are collected from the input and inserted alphabetically rather than hardcoded, so new diagnostic rules don't require formatter changes.

Sorted arrays: include, exclude, ignore, extraPaths, strict.

[tool.ty]

ty is Astral's fast Python type checker, written in Rust. See its configuration reference.

Keys are ordered src → respect-ignore-files → environment → rules → terminal → overrides; the src array is sorted.

Key ordering: src → respect-ignore-files → environment → rules → terminal → overrides (last).

Sorted arrays: src.

The schema is still pre-1.0; unknown keys are alphabetized after the canonical set.

[tool.pytest.ini_options]

pytest is a feature-rich testing framework for Python. See its configuration reference.

Keys in the ini_options block follow the pytest reference order; set-semantic arrays are sorted, while addopts and pythonpath are preserved.

Key ordering: pytest itself → discovery → CLI arguments → markers/parametrize → warnings → doctest → output → logging (capture / CLI / file) → JUnit XML → cache and tmp_path → assertion / faulthandler.

Sorted arrays (set semantics): testpaths, norecursedirs, collect_ignore, collect_ignore_glob, python_files, python_classes, python_functions, markers, filterwarnings, doctest_optionflags, usefixtures, required_plugins.

Preserved as written: addopts (CLI argv, order matters) and pythonpath (a search path with priority semantics).

# Before
[tool.pytest.ini_options]
log_cli_level = "INFO"
markers = [ "slow: marks tests as slow", "fast: marks tests as fast" ]
addopts = [ "--strict-markers", "-ra" ]
testpaths = [ "tests" ]
minversion = "8"

# After
[tool.pytest]
ini_options.minversion = "8"
ini_options.testpaths = [ "tests" ]
ini_options.addopts = [ "--strict-markers", "-ra" ]
ini_options.markers = [ "fast: marks tests as fast", "slow: marks tests as slow" ]
ini_options.log_cli_level = "INFO"

[tool.coverage]

coverage.py measures code coverage of Python programs. See its configuration reference.

Keys follow coverage.py's workflow phases (run → paths → report → output formats) with related options kept adjacent; set-semantic arrays are sorted.

Key ordering: coverage.py's workflow phases:

  1. Run phase (run.*): data collection
    • Source selection: source → source_pkgs → source_dirs
    • File filtering: include → omit
    • Measurement: branch → cover_pylib → timid
    • Execution context: command_line → concurrency → context → dynamic_context
    • Data management: data_file → parallel → relative_files
    • Extensions: plugins
    • Debugging: debug → debug_file → disable_warnings
    • Other: core → patch → sigterm
  2. Paths (paths.*): path mapping between source locations
  3. Report phase (report.*): general reporting
    • Thresholds: fail_under → precision
    • File filtering: include → omit → include_namespace_packages
    • Line exclusion: exclude_lines → exclude_also
    • Partial branches: partial_branches → partial_also
    • Output control: skip_covered → skip_empty → show_missing
    • Formatting: format → sort
    • Error handling: ignore_errors
  4. Output formats (after report)
    • html.*: directory → title → extra_css → show_contexts → skip_covered → skip_empty
    • json.*: output → pretty_print → show_contexts
    • lcov.*: output → line_checksums
    • xml.*: output → package_depth

Related options stay adjacent: include / omit, exclude_lines / exclude_also, partial_branches / partial_also, and skip_covered / skip_empty.

Sorted arrays:

Run phase
source, source_pkgs, source_dirs, include, omit, concurrency, plugins, debug, disable_warnings
Report phase
include, omit, exclude_lines, exclude_also, partial_branches, partial_also
# Before
[tool.coverage]
report.exclude_also = ["if TYPE_CHECKING:"]
report.omit = ["tests/*"]
run.branch = true
run.omit = ["tests/*"]

# After
[tool.coverage]
run.omit = [ "tests/*" ]
run.branch = true
report.omit = [ "tests/*" ]
report.exclude_also = [ "if TYPE_CHECKING:" ]

[tool.tox]

tox automates and standardizes testing across multiple Python environments. See its configuration reference.

A [tool.tox] block in pyproject.toml reuses the tox-toml-fmt rules, so it is formatted identically to a standalone tox.toml.

Reuses the rules from tox-toml-fmt: alias normalization (envlist → env_list, setenv → set_env, etc.), canonical key ordering for the root table and every env table, PEP 508 requirement normalization and sorting in deps and constraints, sorted pass_env (inline-table entries first), version-aware env_list sorting (py313 before py312 before py311), and inline-table reordering for replace, prefix, product, and value directives.

See the tox-toml-fmt documentation for the full schema and per-key behavior; the only difference here is the namespace (tool.tox instead of the root table).

[tool.bumpversion]

bump-my-version (the successor to bumpversion) updates version strings across files and tags releases. See its configuration reference.

Keys are ordered identity → format → tag → commit → behavior → files / parts.

Key ordering: identity (current_version) → format (parse, serialize, search, replace, regex, ignore_missing_*) → tag (tag, sign_tags, tag_name, tag_message) → commit (allow_dirty, commit, commit_args, message, moveable_tags) → behavior → files / parts (arrays of tables, last).

[tool.commitizen]

Commitizen enforces conventional commits and automates version bumps and changelogs. See its configuration reference.

Keys are ordered rule selection → version source → bump behavior → tag/sign → changelog → hooks → customize.

Key ordering: rule selection (name, schema, schema_pattern, allowed_prefixes) → version source (version, version_scheme, version_provider, version_files) → bump behavior → tag/sign → changelog → hooks (pre_bump_hooks, post_bump_hooks) → customize.

Sorted arrays: version_files, allowed_prefixes, extras, extra_files.

[tool.semantic_release]

python-semantic-release automates versioning and releases from commit history. See its configuration reference.

Keys are ordered tag/version → assets → version source → repo → commit parser → branches → publish → changelog → remote; version and asset lists are sorted.

Key ordering: tag/version → assets → version source → repo → commit parser → branches → publish → changelog → remote.

Sorted arrays: version_variables, version_toml, assets, exclude_commit_patterns.

[tool.towncrier]

towncrier builds release notes from news-fragment files. See its configuration reference.

Keys are ordered package identity → news location → rendering → behavior → type / section; the ignore glob list is sorted, while changelog display order is preserved.

Key ordering: package identity (name, version, package, package_dir) → news location (directory, filename, start_string, template, title_format, issue_format, underlines) → rendering (wrap, all_bullets, single_file, orphan_prefix, create_eof_newline, create_add_extension) → behavior (ignore) → type and section (arrays of tables, last).

[[tool.towncrier.type]] entries get keys ordered directory → name → showcontent; [[tool.towncrier.section]] entries get path → name → showcontent. Array order is preserved (display order in the rendered changelog).

Sorted arrays: ignore (file globs to skip).

[tool.pyproject-fmt]

The formatter's own configuration table.

Keys are ordered to match the documented configuration sequence; the expand_tables, collapse_tables, and skip_wrap_for_keys lists are sorted and deduplicated.

Key ordering: column_width → indent → keep_full_version → generate_python_version_classifiers → max_supported_python → table_format → sub_table_spacing → separate_root_table → expand_tables → collapse_tables → skip_wrap_for_keys. Unrecognized keys are appended alphabetically.

Sorted arrays: expand_tables, collapse_tables, skip_wrap_for_keys. Each is matched as a set, so sorting and dropping byte-identical duplicates leaves behavior unchanged. Duplicate removal keeps case variants distinct, matching the case-sensitive lookups these lists feed.

# Before
[tool.pyproject-fmt]
keep_full_version = true
column_width = 120
skip_wrap_for_keys = ["b", "a", "a"]
indent = 4

# After
[tool.pyproject-fmt]
column_width = 120
indent = 4
keep_full_version = true
skip_wrap_for_keys = [ "a", "b" ]

Other Tables

Any unrecognized tables are preserved and reordered according to standard table ordering rules. Keys within unknown tables are not reordered or normalized.