refactor: PEP 695 generic syntax for SSZ collections and Store

src/lean_spec/forks/lstar/store.py

@@ -4,9 +4,9 @@
 The Store tracks all information required for the LMD GHOST forkchoice algorithm.
 """
 
-__all__ = ["AttestationSignatureEntry", "BlockT", "StateT", "Store"]
+__all__ = ["AttestationSignatureEntry", "Store"]
 
-from typing import Generic, NamedTuple, TypeVar
+from typing import NamedTuple
 
 from pydantic import Field
 
@@ -21,12 +21,6 @@
 from lean_spec.types.base import StrictBaseModel
 from lean_spec.types.container import Container
 
-StateT = TypeVar("StateT", bound=Container)
-"""Per-fork post-state type tracked alongside each known block."""
-
-BlockT = TypeVar("BlockT", bound=Container)
-"""Per-fork block type stored in the forkchoice view."""
-
 
 class AttestationSignatureEntry(NamedTuple):
     """
@@ -40,7 +34,7 @@ class AttestationSignatureEntry(NamedTuple):
     signature: Signature
 
 
-class Store(StrictBaseModel, Generic[StateT, BlockT]):
+class Store[StateT: Container, BlockT: Container](StrictBaseModel):
     """
     Forkchoice store tracking chain state and validator attestations.
 

src/lean_spec/types/collections.py

@@ -8,10 +8,8 @@
     IO,
     Any,
     ClassVar,
-    Generic,
     Protocol,
     Self,
-    TypeVar,
     cast,
     overload,
     override,
@@ -38,14 +36,6 @@ class IntFieldElement(Protocol):
     value: int
 
 
-T = TypeVar("T", bound=SSZType)
-"""Generic type parameter for SSZ collection elements.
-
-Bound to SSZType to ensure elements are valid SSZ types.
-Enables type checkers to infer correct return types for indexed access.
-"""
-
-
 def _extract_element_type_from_generic(cls: type, origin_class: type) -> type[SSZType] | None:
     """Extract ELEMENT_TYPE from Pydantic's generic metadata."""
     for base in cls.__bases__:
@@ -94,7 +84,7 @@ def _validate_offsets(offsets: list[int], scope: int, type_name: str) -> None:
         )
 
 
-class SSZVector(SSZModel, Generic[T]):
+class SSZVector[T: SSZType](SSZModel):
     """Fixed-length, immutable SSZ sequence.
 
     Contains exactly LENGTH elements of type ELEMENT_TYPE.
@@ -260,7 +250,7 @@ def elements(self) -> list[T]:
         return list(self.data)
 
 
-class SSZList(SSZModel, Generic[T]):
+class SSZList[T: SSZType](SSZModel):
     """Variable-length SSZ sequence with a maximum capacity.
 
     Contains between 0 and LIMIT elements of type ELEMENT_TYPE.