refactor(node): make fork required in _try_load_store_from_database (leanEthereum#987)

The store loader always receives a concrete fork from its only production
caller, which asserts the fork is an LstarSpec before calling. The optional,
defaulted fork parameter and its None branch were dead: nothing ever fell
back to the base Store class.

Make fork a required positional parameter, drop the None default, and remove
the None-handling branch so the store class always comes from the fork. Update
all test callers to pass the fork explicitly.

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

Author: tcoratger

src/lean_spec/node/node.py

@@ -226,7 +226,7 @@ def from_genesis(cls, config: NodeConfig) -> Node:
         # If the database contains valid state, resume from there.
         # Otherwise, fall through to genesis initialization.
         store = cls._try_load_store_from_database(
-            database, validator_index, config.genesis_time, config.time_fn, fork
+            database, validator_index, fork, config.genesis_time, config.time_fn
         )
 
         # An explicit anchor wins over genesis synthesis but loses to the database.
@@ -375,9 +375,9 @@ async def publish_and_process_block(block: SignedBlock) -> None:
     def _try_load_store_from_database(
         database: Database | None,
         validator_index: ValidatorIndex | None,
+        fork: ForkProtocol,
         genesis_time: Uint64 | None = None,
         time_fn: Callable[[], float] = time.time,
-        fork: ForkProtocol | None = None,
     ) -> Store | None:
         """
         Try to load forkchoice store from existing database state.
@@ -393,9 +393,9 @@ def _try_load_store_from_database(
         Args:
             database: Database to load from.
             validator_index: Validator index for the store instance.
+            fork: Fork specification for store construction.
             genesis_time: Unix timestamp of genesis (slot 0).
             time_fn: Wall-clock time source.
-            fork: Fork specification for store construction.
 
         Returns:
             Loaded Store or None if no valid state exists.
@@ -443,8 +443,7 @@ def _try_load_store_from_database(
         #
         # The store starts with just the head block and state.
         # Additional blocks can be loaded on demand or via sync.
-        store_cls = fork.store_class if fork is not None else Store
-        return store_cls(
+        return fork.store_class(
             time=Interval(store_time),
             config=head_state.config,
             head=head_root,

tests/node/test_node.py

@@ -174,21 +174,28 @@ class TestDatabaseLoading:
 
     def test_returns_none_when_no_database(self) -> None:
         """No database returns None."""
-        assert Node._try_load_store_from_database(None, validator_index=None) is None
+        assert (
+            Node._try_load_store_from_database(None, validator_index=None, fork=LstarSpec()) is None
+        )
 
     def test_returns_none_when_no_head_root(self) -> None:
         """Empty database returns None."""
         empty_db = SQLiteDatabase(":memory:", State, Block)
 
-        assert Node._try_load_store_from_database(empty_db, validator_index=None) is None
+        assert (
+            Node._try_load_store_from_database(empty_db, validator_index=None, fork=LstarSpec())
+            is None
+        )
 
     def test_returns_none_when_block_missing(self) -> None:
         """A head root pointing at no stored block returns None."""
         head_root, _, _, _ = _make_block_state_checkpoint()
         db = SQLiteDatabase(":memory:", State, Block)
         db.put_head_root(head_root)
 
-        assert Node._try_load_store_from_database(db, validator_index=None) is None
+        assert (
+            Node._try_load_store_from_database(db, validator_index=None, fork=LstarSpec()) is None
+        )
 
     def test_returns_none_when_state_missing(self) -> None:
         """A head root with a stored block but no stored state returns None."""
@@ -197,7 +204,9 @@ def test_returns_none_when_state_missing(self) -> None:
         db.put_block(block, head_root)
         db.put_head_root(head_root)
 
-        assert Node._try_load_store_from_database(db, validator_index=None) is None
+        assert (
+            Node._try_load_store_from_database(db, validator_index=None, fork=LstarSpec()) is None
+        )
 
     def test_returns_none_when_justified_missing(self) -> None:
         """A populated head with no justified checkpoint returns None."""
@@ -207,7 +216,9 @@ def test_returns_none_when_justified_missing(self) -> None:
         db.put_state(state, head_root)
         db.put_head_root(head_root)
 
-        assert Node._try_load_store_from_database(db, validator_index=None) is None
+        assert (
+            Node._try_load_store_from_database(db, validator_index=None, fork=LstarSpec()) is None
+        )
 
     def test_returns_none_when_finalized_missing(self) -> None:
         """A populated head with a justified but no finalized checkpoint returns None."""
@@ -218,7 +229,9 @@ def test_returns_none_when_finalized_missing(self) -> None:
         db.put_head_root(head_root)
         db.put_justified_checkpoint(checkpoint)
 
-        assert Node._try_load_store_from_database(db, validator_index=None) is None
+        assert (
+            Node._try_load_store_from_database(db, validator_index=None, fork=LstarSpec()) is None
+        )
 
     def test_successful_load_uses_wall_clock_time(self) -> None:
         """Store time uses wall clock when it exceeds block-based time."""
@@ -230,6 +243,7 @@ def test_successful_load_uses_wall_clock_time(self) -> None:
         store = Node._try_load_store_from_database(
             db,
             validator_index=ValidatorIndex(0),
+            fork=LstarSpec(),
             genesis_time=GENESIS_TIME,
             time_fn=lambda: wall_time,
         )
@@ -253,6 +267,7 @@ def test_load_uses_block_time_when_wall_clock_behind(self) -> None:
         store = Node._try_load_store_from_database(
             db,
             validator_index=ValidatorIndex(0),
+            fork=LstarSpec(),
             genesis_time=GENESIS_TIME,
             time_fn=lambda: wall_time,
         )
@@ -389,6 +404,7 @@ def test_falls_back_to_database_genesis_time(self) -> None:
         store = Node._try_load_store_from_database(
             db,
             validator_index=None,
+            fork=LstarSpec(),
             genesis_time=None,
             time_fn=lambda: wall_time,
         )
@@ -409,6 +425,7 @@ def test_zero_genesis_time_when_database_returns_none(self) -> None:
         store = Node._try_load_store_from_database(
             db,
             validator_index=None,
+            fork=LstarSpec(),
             genesis_time=None,
             time_fn=lambda: wall_time,
         )