Address review feedback

Author: till-varoquaux

peps/pep-9999.rst

@@ -32,7 +32,7 @@ that was concise but problematic for type checkers and runtime defaults::
         id: int = Field(gt=0)
         name: str = Field(min_length=3)
 
-The transition to ``Annotated`` cleanly separated type from metadata but
+The transition to ``Annotated`` cleanly separated types from metadata but
 introduced visual noise and cognitive overhead. Library authors often surface
 "special" types, like ``PositiveInt`` or ``EmailStr``, to hide this verbosity.
 These aliases are discoverable but inherently limited. Users needing unique
@@ -125,7 +125,7 @@ The proposed syntax is straightforward to implement. Prototypes for Mypy,
 Pyright, and Ruff are compact. Since ``@`` is already a valid expression
 operator, these tools do not require parser changes. They handle the new syntax
 during semantic analysis. Ruff has already prototyped a ``pyupgrade`` rule
-(``UP051``) for automated conversion. This enables large codebases to
+for automated conversion. This enables large codebases to
 migrate to the new syntax with minimal manual effort.
 
 CPython prototype testing confirms that libraries like ``typer`` and
@@ -201,14 +201,10 @@ The ``repr()`` of an ``AnnotatedType`` uses the shorthand syntax::
     >>> int @ Field(gt=0)
     int @ Field(gt=0)
 
-``__copy__`` and ``__deepcopy__`` are not supported on ``AnnotatedType``
-objects and will raise ``AttributeError``. This is a deliberate design
-choice to avoid ambiguity around shared mutable metadata.
-
 ``AnnotatedType`` objects support pickling via ``copyreg``, reconstructing
 through ``AnnotatedType[origin, *metadata]``.
 
-``None`` on the left-hand side is accepted and uses ``NoneType`` as the
+``None`` on the left-hand side is accepted and uses ``None`` as the
 origin::
 
     >>> None @ Field()
@@ -218,16 +214,9 @@ Supported Left-Hand Operands
 -----------------------------
 
 The ``@`` operator is implemented by adding ``nb_matrix_multiply`` to the
-metatype (``type``) and to several typing-related types. The operator fires
-when the left-hand operand is any of the following:
-
-- A type object (any class, including built-ins like ``int`` and ``str``)
-- ``None`` (treated as ``NoneType``)
-- ``types.UnionType`` (e.g., ``int | str``)
-- ``types.GenericAlias`` (e.g., ``list[int]``)
-- ``typing.TypeVar``, ``typing.ParamSpec``, ``typing.TypeVarTuple``
-- ``typing.TypeAliasType``
-- ``types.AnnotatedType`` (for chaining)
+metatype (``type``) and to several typing-related types. The operator is
+supported for any left-hand operand that currently supports the ``|``
+operator for making a union.
 
 For all other left-hand operands, the operator returns ``NotImplemented``,
 allowing normal ``__matmul__`` dispatch to proceed.
@@ -288,10 +277,12 @@ is trapped inside the unresolved string and cannot be inspected until the
 forward reference is resolved. This is a blocking issue for libraries like
 Pydantic and FastAPI, which inspect metadata at class-definition time.
 
-This proposal introduces a new format, ``Format.FORWARDREF_STRUCTURAL``,
-which evaluates compound type expressions **structurally**. When a name
-cannot be resolved, only that name is wrapped in ``ForwardRef``; the
-surrounding operators are still evaluated. The example above produces::
+This proposal introduces a new format, ``Format.FORWARDREF_STRUCTURAL``.
+This format assumes typing semantics and evaluates compound type expressions
+**structurally**. It always returns an ``AnnotatedType`` for ``@``, a union
+for ``|``, and a ``GenericAlias`` for subscripting. When a name cannot be
+resolved, only that name is wrapped in ``ForwardRef``; the surrounding
+operators are still evaluated. The example above produces::
 
     AnnotatedType(ForwardRef('NotYetDefined'), Field(gt=0))
 
@@ -348,7 +339,7 @@ metaclass.
 The private ``typing._AnnotatedAlias`` class is retained as a deprecated
 compatibility shim. Code using ``isinstance(x, typing._AnnotatedAlias)``
 will continue to work but emit a ``DeprecationWarning``. The shim is
-scheduled for removal in Python 3.23.
+scheduled for removal in Python 3.18.
 
 Code that should be updated: