diff --git a/reorder_python_imports.py b/reorder_python_imports.py
index d66dc4b..a248771 100644
--- a/reorder_python_imports.py
+++ b/reorder_python_imports.py
@@ -421,7 +421,7 @@ def _fix_file(
 # Using:
 #     flake8-typing-imports==1.15.0
 #     mypy-extensions==1.0.0
-#     typing-extensions==4.8.0
+#     typing-extensions==4.12.1
 REPLACES[(3, 6)].update((
     'typing_extensions=typing:AbstractSet',
     'typing_extensions=typing:AnyStr',
@@ -433,12 +433,10 @@ def _fix_file(
     'typing_extensions=typing:ClassVar',
     'typing_extensions=typing:Collection',
     'typing_extensions=typing:Container',
-    'typing_extensions=typing:ContextManager',
     'typing_extensions=typing:Coroutine',
     'typing_extensions=typing:DefaultDict',
     'typing_extensions=typing:Dict',
     'typing_extensions=typing:FrozenSet',
-    'typing_extensions=typing:Generator',
     'typing_extensions=typing:Generic',
     'typing_extensions=typing:Hashable',
     'typing_extensions=typing:IO',
@@ -472,8 +470,6 @@ def _fix_file(
 ))
 REPLACES[(3, 7)].update((
     'mypy_extensions=typing:NoReturn',
-    'typing_extensions=typing:AsyncContextManager',
-    'typing_extensions=typing:AsyncGenerator',
     'typing_extensions=typing:ChainMap',
     'typing_extensions=typing:Counter',
     'typing_extensions=typing:Deque',
@@ -484,8 +480,6 @@ def _fix_file(
     'mypy_extensions=typing:TypedDict',
     'typing_extensions=typing:Final',
     'typing_extensions=typing:OrderedDict',
-    'typing_extensions=typing:SupportsIndex',
-    'typing_extensions=typing:runtime_checkable',
 ))
 REPLACES[(3, 9)].update((
     'typing_extensions=typing:Annotated',
@@ -520,15 +514,14 @@ def _fix_file(
 ))
 REPLACES[(3, 12)].update((
     'typing_extensions=typing:NamedTuple',
-    'typing_extensions=typing:Protocol',
     'typing_extensions=typing:SupportsAbs',
     'typing_extensions=typing:SupportsBytes',
     'typing_extensions=typing:SupportsComplex',
     'typing_extensions=typing:SupportsFloat',
+    'typing_extensions=typing:SupportsIndex',
     'typing_extensions=typing:SupportsInt',
     'typing_extensions=typing:SupportsRound',
     'typing_extensions=typing:TypeAliasType',
-    'typing_extensions=typing:TypedDict',
     'typing_extensions=typing:Unpack',
     'typing_extensions=typing:dataclass_transform',
     'typing_extensions=typing:override',
diff --git a/testing/generate-typing-rewrite-info b/testing/generate-typing-rewrite-info
index a107663..03923b7 100755
--- a/testing/generate-typing-rewrite-info
+++ b/testing/generate-typing-rewrite-info
@@ -27,25 +27,35 @@ import typing_extensions
 # - Any was change in Python 3.11 so it can be used as a base class
 # - From 3.11, NamedTuple and TypedDict can inherit from Generic;
 #   from 3.12 onwards, the __orig_bases__ attribute
-#   is properly set on NamedTuple and TypedDict classes
+#   is properly set on NamedTuple and TypedDict classes.
+#   From 3.13 onwards, TypedDict fields can be marked as `ReadOnly`.
 # - The frozen_default parameter was added to dataclass_transform in py312
 # - isinstance() checks are 20x faster or more for runtime-checkable protocols
-#   on py312; typing_extensions backports the performance improvement
+#   on py312; typing_extensions backports the performance improvement.
+#   It also backports several bugfixes from early py312 patch releases.
 # - The repr of Unpack was changed in py312 as part of PEP 692;
 #   typing_extensions backports this
 # - Python 3.12 adds the PEP 695 infer_variance parameter for TypeVar.
-#   The PEP 696 default parameter for TypeVar, TypeVarTuple, and ParamSpec
-#   is under consideration for Python 3.13.
+# - The PEP 696 default parameter for TypeVar, TypeVarTuple, and ParamSpec
+#   has been added in Python 3.13.
+# - (Async)Generator now has a default value for all type parameters except
+#   the first one on py313+, and (Async)ContextManager now has an optional
+#   second parameter with a default value; typing_extensions backports these
+#   changes.
 CUSTOM_TYPING_EXT_SYMBOLS = {
     (3, 9): {'get_type_hints'},
     (3, 10): {'get_origin', 'get_args', 'Literal', 'NewType'},
     (3, 11): {'Any', 'final', 'overload'},
     (3, 12): {
-        'Protocol', 'SupportsInt', 'SupportsFloat', 'SupportsComplex',
+        'SupportsInt', 'SupportsFloat', 'SupportsComplex',
         'SupportsBytes', 'SupportsAbs', 'SupportsRound', 'NamedTuple',
-        'TypedDict', 'Unpack', 'dataclass_transform',
+        'Unpack', 'dataclass_transform', 'SupportsIndex',
+    },
+    (3, 13): {
+        'AsyncContextManager', 'ContextManager', 'AsyncGenerator', 'Generator',
+        'TypeVar', 'TypeVarTuple', 'ParamSpec', 'TypedDict', 'Protocol',
+        'runtime_checkable',
     },
-    (3, 13): {'TypeVar', 'TypeVarTuple', 'ParamSpec'},
 }