Dose "closest" mean closest to the working directory or the target file?

[otakutyrant]

The documentation says:

Similar to ESLint, Ruff supports hierarchical configuration, such that the "closest" config file in the directory hierarchy is used for every individual file, with all paths in the config file (e.g., exclude globs, src paths) being resolved relative to the directory containing that config file.

However, this result confused me:

$ ruff format --force-exclude --verbose b/c.py
[2025-12-07][23:05:34][ruff::resolve][DEBUG] Using configuration file (via parent) at: /home/otakutyrant/Projects/a/pyp
roject.toml
[2025-12-07][23:05:34][ruff_workspace::resolver][DEBUG] Ignored path via `exclude`: "/home/otakutyrant/Projects/a/b/c.p
y"
warning: No Python files found under the given path(s)
$ cat pyproject.toml
[tool.ruff]
$ cat b/pyproject.toml
[tool.ruff]
exclude = ["c.py"]
$ tree .
.
├── b
│   ├── c.py
│   └── pyproject.toml
└── pyproject.toml

2 directories, 3 files

The working directory is a.

ruff says that it use the parent configuration file a/pyproject.toml but it excludes a/b/c.py because of the configuration file a/b/pyproject.toml.

[MichaReiser]

Ruff uses the configuration closest to the checked file, but its configuration discovery always starts from the current working directory.

cd b
ruff format --force-exclude --verbose c.py

should work, because Ruff skips the /pyproject.toml.

Ruff skips subdirectories if the parent configuration excludes them, since traversing excluded directories like .venv can be expensive.

[otakutyrant]

Good. Thank you!