Max Line Length in style guide ignored with python 3.14 when checking multiple files

how did you install flake8?

Installed on demand from TOML requirements as part of uv run command launch

unmodified output of flake8 --bug-report

{
  "platform": {
    "python_implementation": "CPython",
    "python_version": "3.14.2",
    "system": "Linux"
  },
  "plugins": [
    {
      "plugin": "mccabe",
      "version": "0.7.0"
    },
    {
      "plugin": "pep8-naming",
      "version": "0.15.1"
    },
    {
      "plugin": "pycodestyle",
      "version": "2.14.0"
    },
    {
      "plugin": "pyflakes",
      "version": "3.4.0"
    }
  ],
  "version": "7.3.0"
}

describe the problem

what I expected to happen

when using flake8 programmatically it should be possible to check multiple files with the configured style guide. This works correctly with python3.12 but seems to be ignored when using python 3.14

set up style guide

Python 3.14.2 (main, Jan  9 2026, 09:06:43) [GCC 8.5.0 20210514 (Red Hat 8.5.0-28.0.1)] on linux
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>>> from flake8.api import legacy as flake8
>>> ignore_list = []
>>> line_length = 88
>>> style_guide = flake8.get_style_guide(extend_ignore=ignore_list, max_line_length=line_length, color="never")
>>> style_guide.options
Namespace(verbose=0, output_file=None, append_config=[], config=None, isolated=False, enable_extensions=None, require_plugins=None, filenames=[], quiet=0, color='never', count=False, exclude=['.svn', 'CVS', '.bzr', '.hg', '.git', '__pycache__', '.tox', '.nox', '.eggs', '*.egg'], extend_exclude=[], filename=['*.py'], stdin_display_name='stdin', format='default', hang_closing=False, ignore=None, extend_ignore=[], per_file_ignores='', max_line_length=88, max_doc_length=None, indent_size=4, select=None, extend_select=None, disable_noqa=False, show_source=False, statistics=False, exit_zero=False, jobs=JobsArgument('auto'), tee=False, benchmark=False, bug_report=False, max_complexity=-1, ignore_names=['setUp', 'tearDown', 'setUpClass', 'tearDownClass', 'setUpModule', 'tearDownModule', 'asyncSetUp', 'asyncTearDown', 'setUpTestData', 'failureException', 'longMessage', 'maxDiff'], classmethod_decorators=['classmethod'], staticmethod_decorators=['staticmethod'], builtins=None, doctests=False, extended_default_ignore=['N818'], extended_default_select=['C90', 'N8', 'F', 'E', 'W'])

Check files ignores the set max_line_length when running with multiple files

>>> style_guide.check_files(['file1.py', 'file2.py'])
file1.py:65:80: E501 line too long (88 > 79 characters)
file1.py:66:80: E501 line too long (85 > 79 characters)
file2.py:17:80: E501 line too long (81 > 79 characters)
file2.py:18:80: E501 line too long (87 > 79 characters)
file2.py:19:80: E501 line too long (88 > 79 characters)
<flake8.api.legacy.Report object at 0x7f070003b4d0>

However running the files individually works ok, and then it is possible to run the two files in the same check correctly

>>> style_guide.check_files(['file1.py'])
<flake8.api.legacy.Report object at 0x7f06ffc50690>
>>> style_guide.check_files(['file2.py'])
<flake8.api.legacy.Report object at 0x7f06ffc507d0>
>>> 
>>> 
>>> style_guide.check_files(['file1.py', 'file2.py'])
<flake8.api.legacy.Report object at 0x7f07001223f0>

Start with the legacy API path used by style_guide.check_files and reproduce the difference between checking one file and multiple files under Python 3.14. Trace how max_line_length is applied during multi-file checks, then verify that the configured value is honored for both files in the reported example.