[rchl]

typing_extensions isn't available at runtime in Sublime Text's plugin host, and sublime_lib doesn't declare it as a runtime dependency. So the unconditional from typing_extensions import Self in flags.py and activity_indicator.py could fail with ImportError.

Changes:

• Enable ruff's flake8-type-checking (TC) rules.
• Set exempt-modules = ["typing", "sublime"]. Ruff exempts typing_extensions by default, which hides exactly this problem. sublime is always present at runtime, so it stays a plain import.
• Apply the TC fixes, which move Self, TracebackType, Iterable and Generator behind TYPE_CHECKING. All of them are used only in annotations, and every affected module has from __future__ import annotations.
• Add typing-extensions to the lint dependency group for type checkers.
• Bump the sublime-text-stubs lower bound.

ruff check and ruff format --check pass.

[deathaxe]

The little amount of such type only imports doesn't really justify overhead of extra TYPE_CHECKING imports.

[FichteFoll]

I do not understand how a TYPE_CHECKING import can qualify as "overhead" for a module that is practically always loaded (and that we load in sublime_lib anyway). Besides, the main goal to enable the TC lint rules is to avoid such issues in the future.

[deathaxe]

It adds useless noise for just gating single imports.

[deathaxe]

There are two justifications for TYPE_CHECKING gates

1. many type only imports which would cause too much overhead at runtime imports
2. keeping incompatible typing syntax out of the way for older runtimes.

[FichteFoll]

By the way, we can also remove the typing-extensions dependency from the docs project now for the same reason.