refactor(ssz): collapse identical hash_tree_root leaf handlers (leanEthereum#1037)

* refactor(ssz): collapse identical hash_tree_root leaf handlers

Four singledispatch handlers for hash_tree_root had byte-identical
bodies: the ones for unsigned integers, booleans, field elements, and
fixed-size byte vectors all merkleized the packed encoded bytes.

Collapse them into one handler registered against all four base types
with stacked explicit registrations. Dispatch precedence is unchanged:
the fixed byte-vector base is a subclass of the bytes builtin, so its
instances still resolve to the new handler while plain bytes,
bytearray, and memoryview keep their distinct handlers. The byte-list,
bitvector, bitlist, vector, list, and container handlers are untouched
because their bodies differ.

Verified with just check (lint, format, types, spell, mdformat) and
uv run fill --fork=lstar --clean -n auto: 539 vectors pass and the
cross-seed determinism check is green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore(vulture): sync whitelist with collapsed hash_tree_root handler

Collapsing the four identical leaf handlers into one left the whitelist
naming the four removed functions and not the new one, so vulture flagged
the new singledispatch handler as unused. Replace the four stale entries
with the single new handler name.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: tcoratger

src/lean_spec/spec/crypto/merkleization.py

@@ -208,18 +208,13 @@ def hash_tree_root(value: object) -> Bytes32:
     raise TypeError(f"hash_tree_root: unsupported value type {type(value).__name__}")
 
 
-@hash_tree_root.register
-def _htr_uint(value: BaseUint) -> Bytes32:
-    return merkleize(_pack_bytes(value.encode_bytes()))
-
-
-@hash_tree_root.register
-def _htr_boolean(value: Boolean) -> Bytes32:
-    return merkleize(_pack_bytes(value.encode_bytes()))
-
-
-@hash_tree_root.register
-def _htr_fp(value: Fp) -> Bytes32:
+@hash_tree_root.register(BaseUint)
+@hash_tree_root.register(Boolean)
+@hash_tree_root.register(Fp)
+@hash_tree_root.register(BaseBytes)
+def _htr_packed_leaf(value: BaseUint | Boolean | Fp | BaseBytes) -> Bytes32:
+    # Each of these encodes to a fixed-width byte string with no length prefix.
+    # The root is the Merkle root of those bytes packed into 32-byte chunks.
     return merkleize(_pack_bytes(value.encode_bytes()))
 
 
@@ -228,11 +223,6 @@ def _htr_bytes(value: bytes) -> Bytes32:
     return merkleize(_pack_bytes(value))
 
 
-@hash_tree_root.register
-def _htr_bytevector(value: BaseBytes) -> Bytes32:
-    return merkleize(_pack_bytes(value.encode_bytes()))
-
-
 @hash_tree_root.register
 def _htr_bytelist(value: BaseByteList) -> Bytes32:
     serialized_bytes = value.encode_bytes()

vulture_whitelist.py

@@ -15,11 +15,8 @@
 
 # Single-dispatch handlers for the hash_tree_root generic function.
 # Dispatched by argument type, so they have no direct call site.
-_htr_uint
-_htr_boolean
-_htr_fp
+_htr_packed_leaf
 _htr_bytes
-_htr_bytevector
 _htr_bytelist
 _htr_bitvector_base
 _htr_bitlist_base