[rejected AI] Fix BOOL conversion of 0 and 1

CHANGES.md

@@ -2,6 +2,10 @@
 
 Unreleased
 
+- `BOOL` converts `0` and `1` to `False` and `True` again instead of raising
+  `AttributeError`. Regression introduced in `8.2.2` by {pr}`2956`.
+  {issue}`3846`
+
 ## Version 8.5.0
 
 Released 2026-08-24

src/click/types.py

@@ -852,9 +852,9 @@ def str_to_bool(value: str | bool) -> bool | None:
 
         Returns `None` if the value does not match any known boolean state.
         """
-        if isinstance(value, bool):
-            return value
-        return BoolParamType.bool_states.get(value.strip().lower())
+        if value in {False, True}:
+            return bool(value)
+        return BoolParamType.bool_states.get(str(value).strip().lower())
 
     def convert(
         self, value: t.Any, param: Parameter | None, ctx: Context | None

tests/test_basic.py

@@ -321,6 +321,8 @@ def cli(on):
         (True, [], True),
         (False, ["--f"], True),
         (False, [], False),
+        (1, [], True),
+        (0, [], False),
         # Boolean flags have a 3-states logic.
         # See: https://github.com/pallets/click/issues/3024#issue-3285556668
         (None, ["--f"], True),