💚 don't require ruff during type-checking

Author: jorenham

tool/_ruff.py

@@ -1,10 +1,16 @@
 import subprocess
 from pathlib import Path
+from typing import TYPE_CHECKING
 
-# see https://github.com/astral-sh/ruff/pull/18224
-from ruff.__main__ import (  # type: ignore[import-untyped]  # pyright: ignore[reportMissingTypeStubs]
-    find_ruff_bin,  # noqa: PLC2701
-)
+if TYPE_CHECKING:
+    # ruff should be optional during type-checking
+    def find_ruff_bin() -> str: ...
+
+else:
+    # see https://github.com/astral-sh/ruff/pull/18224
+    from ruff.__main__ import (  # type: ignore[import-untyped]
+        find_ruff_bin,  # noqa: PLC2701
+    )
 
 
 def ruff_format(source: str) -> str: