Update black to 26.3.1

[pyup-bot]

This PR updates black from 25.12.0 to 26.3.1.

Changelog

26.3.1

Stable style

- Prevent Jupyter notebook magic masking collisions from corrupting cells by using
exact-length placeholders for short magics and aborting if a placeholder can no longer
be unmasked safely (5038)

Configuration

- Always hash cache filename components derived from `--python-cell-magics` so custom
magic names cannot affect cache paths (5038)

_Blackd_

- Disable browser-originated requests by default, add configurable origin allowlisting
and request body limits, and bound executor submissions to improve backpressure
(5039)

26.3.0

Stable style

- Don't double-decode input, causing non-UTF-8 files to be corrupted (4964)
- Fix crash on standalone comment in lambda default arguments (4993)
- Preserve parentheses when ` type: ignore` comments would be merged with other
comments on the same line, preventing AST equivalence failures (4888)

Preview style

- Fix bug where `if` guards in `case` blocks were incorrectly split when the pattern had
a trailing comma (4884)
- Fix `string_processing` crashing on unassigned long string literals with trailing
commas (one-item tuples) (4929)
- Simplify implementation of the power operator "hugging" logic (4918)

Packaging

- Fix shutdown errors in PyInstaller builds on macOS by disabling multiprocessing in
frozen environments (4930)

Performance

- Introduce winloop for windows as an alternative to uvloop (4996)
- Remove deprecated function `uvloop.install()` in favor of `uvloop.new_event_loop()`
(4996)
- Rename `maybe_install_uvloop` function to `maybe_use_uvloop` to simplify loop
installation and creation of either a uvloop/winloop evenloop or default eventloop
(4996)

Output

- Emit a clear warning when the target Python version is newer than the running Python
version, since AST safety checks cannot parse newer syntax. Also replace the
misleading "INTERNAL ERROR" message with an actionable error explaining the version
mismatch (4983)

_Blackd_

- Introduce winloop to be used when windows in use which enables blackd to run faster on
windows when winloop is installed. (4996)

Integrations

- Remove unused gallery script (5030)
- Harden parsing of `black` requirements in the GitHub Action when `use_pyproject` is
enabled so that only version specifiers are accepted and direct references such as
`black  https://...` are rejected. Users should upgrade to the latest version of the
action as soon as possible. This update is received automatically when using
`psf/blackstable`, and is independent of the version of Black installed by the
action. (5031)

Documentation

- Expand preview style documentation with detailed examples for `wrap_comprehension_in`,
`simplify_power_operator_hugging`, and `wrap_long_dict_values_in_parens` features
(4987)
- Add detailed documentation for formatting Jupyter Notebooks (5009)

26.1.0

Highlights

Introduces the 2026 stable style (4892), stabilizing the following changes:

- `always_one_newline_after_import`: Always force one blank line after import
statements, except when the line after the import is a comment or an import statement
(4489)
- `fix_fmt_skip_in_one_liners`: Fix ` fmt: skip` behavior on one-liner declarations,
such as `def foo(): return "mock"  fmt: skip`, where previously the declaration would
have been incorrectly collapsed (4800)
- `fix_module_docstring_detection`: Fix module docstrings being treated as normal
strings if preceded by comments (4764)
- `fix_type_expansion_split`: Fix type expansions split in generic functions (4777)
- `multiline_string_handling`: Make expressions involving multiline strings more compact
(1879)
- `normalize_cr_newlines`: Add `\r` style newlines to the potential newlines to
normalize file newlines both from and to (4710)
- `remove_parens_around_except_types`: Remove parentheses around multiple exception
types in `except` and `except*` without `as` (4720)
- `remove_parens_from_assignment_lhs`: Remove unnecessary parentheses from the left-hand
side of assignments while preserving magic trailing commas and intentional multiline
formatting (4865)
- `standardize_type_comments`: Format type comments which have zero or more spaces
between `` and `type:` or between `type:` and value to ` type: (value)` (4645)

The following change was not in any previous stable release:

- Regenerated the `_width_table.py` and added tests for the Khmer language (4253)

This release alo bumps `pathspec` to v1 and fixes inconsistencies with Git's
`.gitignore` logic (4958). Now, files will be ignored if a pattern matches them, even
if the parent directory is directly unignored. For example, Black would previously
format `exclude/not_this/foo.py` with this `.gitignore`:


exclude/
!exclude/not_this/


Now, `exclude/not_this/foo.py` will remain ignored. To ensure `exclude/not_this/` and
all of it's children are included in formatting (and in Git), use this `.gitignore`:


*/exclude/*
!*/exclude/not_this/


This new behavior matches Git. The leading `*/` are only necessary if you wish to ignore
matching subdirectories (like the previous behavior did), and not just matching root
directories.

Output

- Explicitly shutdown the multiprocessing manager when run in diff mode too (4952)

Integrations

- Upgraded PyPI upload workflow to use Trusted Publishing (4611)

Links

• PyPI: https://pypi.org/project/black
• Changelog: https://data.safetycli.com/changelogs/black/