chore: adopt ruff 0.16.0

planning/changes/2026-06-26.03-type-eof-action-seam.md

@@ -26,13 +26,18 @@ change to what the tool does.
 
 ```python
 @dataclasses.dataclass(frozen=True)
-class Noop: ...        # empty, or already ends with exactly one terminator
+class Noop: ...  # empty, or already ends with exactly one terminator
+
+
 @dataclasses.dataclass(frozen=True)
-class AppendLf: ...    # lacks a trailing newline; append one LF
+class AppendLf: ...  # lacks a trailing newline; append one LF
+
+
 @dataclasses.dataclass(frozen=True)
-class Truncate:        # excess trailing newlines; truncate to `offset` (0 = empty)
+class Truncate:  # excess trailing newlines; truncate to `offset` (0 = empty)
     offset: int
 
+
 _EofAction = Noop | AppendLf | Truncate
 ```
 

pyproject.toml

@@ -73,6 +73,7 @@ ignore = [
     "D213",   # "multi-line-summary-second-line" conflicting with D212
     "COM812", # flake8-commas "Trailing comma missing"
     "ISC001", # flake8-implicit-str-concat
+    "CPY001", # no per-file copyright header
 ]
 isort.lines-after-imports = 2
 isort.no-lines-before = ["standard-library", "local-folder"]