# How the Python in this tree is formatted, and how its imports are ordered.
# `make fmt` applies both, `make fmt-check` asks, and the pre-commit hook in
# `.githooks/` does it for what you staged (`make hooks`).
#
# ruff rather than black: it is one static binary instead of a Python dependency
# chain, it is fast enough that a pre-commit hook is free, and its formatter is
# black's output -- so this is the ecosystem's formatting, not a dialect of it.
#
# Unlike the C side, this is left at the defaults. `.clang-format` argues with
# LLVM in five places because the C here was hand-formatted into a house style
# worth keeping; the Python was not, and a formatter of this kind is only worth
# having if there is nothing left to argue about. Every knob turned here is an
# argument somebody has to have again later.

# The version this tree was formatted with, enforced by ruff itself: a formatter
# whose output moves between releases turns "formatted" into "formatted by
# whoever committed last", and the diff lands on the next person. A mismatch is
# refused with both versions named rather than quietly reformatting everything.
#
# `make tools` installs exactly this one. Bumping it is one line here, one in the
# Makefile, and a reformat commit -- the honest cost of a new version.
required-version = "==0.16.3"

target-version = "py39"
line-length = 88

# The vendored terminal core is somebody else's tree, pinned by commit (D12), and
# `.scratch/` is where experiments go to be untidy in peace.
extend-exclude = ["vendor", ".scratch"]

[lint]
# Import sorting, and nothing else. `ruff check` can enforce a great deal more and
# one day it might, but this hook's job is formatting: one that also refused a
# commit over an unused variable would be a different feature, and not one anybody
# asked for.
#
# Sorting imports is safe here in a way sorting C includes is not -- which is why
# `.clang-format` says `SortIncludes: Never` and this does the opposite. A C
# include order can be load-bearing (`_GNU_SOURCE` before the system headers, and
# a grouping somebody wrote by hand); Python import order is not, and where it
# genuinely is, a statement between the imports ends the block ruff will sort. The
# test files rely on exactly that: `sys.path.insert(...)` sits between the standard
# library and `from harness import ...`, so the harness import cannot be hoisted
# above the line that makes it importable.
select = ["I"]