`requires-python` and the CI pin already said 3.14, but ruff, mypy and pylint
were still grading against 3.10 -- three tools judging an interpreter nothing
runs any more, and ruff withholding the pyupgrade fixes that only become safe
at the newer target. `pin_ci_python.py` rewrites exactly these three knobs.
What the stale target was hiding: 118 sites on `datetime.timezone.utc` instead
of `datetime.UTC` (UP017), two classes still written with `Generic[...]` rather
than PEP 695 syntax, and ruff's stable formatter applying PEP 758 --
`except (A, B):` becomes `except A, B:`. That last one makes the source
3.14-only at the syntax level, which is what `requires-python = ">=3.14"`
already promised; kuhy chose it deliberately over holding ruff a release back
(2026-08-29).
The PEP 695 fix needed a hand: ruff rewrote `class WidgetGroup(Generic[_W])`
to `class WidgetGroup[W: tk.Misc]` but left the body annotated with the
module-level `_W`, a *different* type variable -- mypy caught it as "a function
returning TypeVar should receive at least one argument containing the same
TypeVar". Renamed the body to the new parameter, gave `FrameGroup.__init__`
the concrete `list[tk.Frame]` it always wrapped, and deleted the two now-dead
module-level TypeVars.
ruff, ruff-format, mypy --strict and both pylint passes clean at the new target.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SfnJmxxsZ534AKk16rC2Gr
