diff --git a/packages/testing/src/consensus_testing/forks/forks.py b/packages/testing/src/consensus_testing/forks/forks.py
index bfb6b2fd6..21677c383 100644
--- a/packages/testing/src/consensus_testing/forks/forks.py
+++ b/packages/testing/src/consensus_testing/forks/forks.py
@@ -2,8 +2,6 @@
 
 from framework.forks import BaseFork
 
-from lean_spec.spec.forks.lstar.spec import LstarSpec
-
 
 class Lstar(BaseFork):
     """Lstar fork — base fork for the lean Ethereum protocol."""
@@ -12,8 +10,3 @@ class Lstar(BaseFork):
     def name(cls) -> str:
         """Return the fork name."""
         return "Lstar"
-
-    @classmethod
-    def spec_class(cls) -> type[LstarSpec]:
-        """Return the ForkProtocol implementation for this fork."""
-        return LstarSpec
diff --git a/packages/testing/src/consensus_testing/test_fixtures/fork_choice.py b/packages/testing/src/consensus_testing/test_fixtures/fork_choice.py
index f90a88ade..f3c448785 100644
--- a/packages/testing/src/consensus_testing/test_fixtures/fork_choice.py
+++ b/packages/testing/src/consensus_testing/test_fixtures/fork_choice.py
@@ -11,6 +11,7 @@
 
 from pydantic import Field, model_validator
 
+from consensus_testing.genesis import generate_pre_state
 from consensus_testing.keys import XmssKeyManager
 from consensus_testing.test_fixtures.base import BaseConsensusFixture
 from consensus_testing.test_types import (
@@ -56,12 +57,12 @@ class ForkChoiceTest(BaseConsensusFixture):
     description: ClassVar[str] = "Tests event-driven fork choice through Store operations"
     """Human-readable summary for fixture documentation."""
 
-    anchor_state: State | None = None
+    anchor_state: State = Field(default_factory=generate_pre_state)
     """
     Initial trusted consensus state.
 
-    Most tests start from genesis.
-    The pytest fixture provides this automatically.
+    Defaults to the standard genesis state.
+    Spell it out only when the test needs a non-default anchor.
     """
 
     anchor_block: Block | None = None
@@ -120,7 +121,7 @@ def set_anchor_block_default(self) -> Self:
         Most tests start from genesis.
         Deriving the anchor block from state reduces boilerplate.
         """
-        if self.anchor_block is None and self.anchor_state is not None:
+        if self.anchor_block is None:
             # Build a minimal genesis block from the state's header fields.
             #
             # The state already contains the block header.
@@ -177,7 +178,6 @@ def make_fixture(self) -> Self:
         #
         # Pydantic validators should have populated these fields.
         # These assertions guard against misuse.
-        assert self.anchor_state is not None, "anchor state must be set before making fixture"
         assert self.anchor_block is not None, "anchor block must be set before making fixture"
         assert self.max_slot is not None, "max slot must be set before making fixture"
 
diff --git a/packages/testing/src/consensus_testing/test_fixtures/state_transition.py b/packages/testing/src/consensus_testing/test_fixtures/state_transition.py
index d41d7c7d1..d14ce4b48 100644
--- a/packages/testing/src/consensus_testing/test_fixtures/state_transition.py
+++ b/packages/testing/src/consensus_testing/test_fixtures/state_transition.py
@@ -2,8 +2,9 @@
 
 from typing import Any, ClassVar
 
-from pydantic import ConfigDict, PrivateAttr, field_serializer
+from pydantic import ConfigDict, Field, PrivateAttr, field_serializer
 
+from consensus_testing.genesis import generate_pre_state
 from consensus_testing.keys import XmssKeyManager
 from consensus_testing.test_fixtures.base import BaseConsensusFixture
 from consensus_testing.test_types import AggregatedAttestationSpec, BlockSpec, StateExpectation
@@ -50,8 +51,13 @@ class StateTransitionTest(BaseConsensusFixture):
 
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
-    pre: State
-    """The initial consensus state before processing."""
+    pre: State = Field(default_factory=generate_pre_state)
+    """
+    The initial consensus state before processing.
+
+    Defaults to the standard genesis state.
+    Spell it out only when the test needs a non-default pre-state.
+    """
 
     blocks: list[BlockSpec]
     """
diff --git a/packages/testing/src/consensus_testing/test_fixtures/verify_signatures.py b/packages/testing/src/consensus_testing/test_fixtures/verify_signatures.py
index ce52c8e00..2e9b66fd6 100644
--- a/packages/testing/src/consensus_testing/test_fixtures/verify_signatures.py
+++ b/packages/testing/src/consensus_testing/test_fixtures/verify_signatures.py
@@ -6,6 +6,7 @@
 
 from pydantic import Field
 
+from consensus_testing.genesis import generate_pre_state
 from consensus_testing.keys import XmssKeyManager
 from consensus_testing.test_fixtures.base import BaseConsensusFixture
 from consensus_testing.test_types import BlockSpec
@@ -39,11 +40,11 @@ class VerifySignaturesTest(BaseConsensusFixture):
     format_name: ClassVar[str] = "verify_signatures_test"
     description: ClassVar[str] = "Tests signature verification for signed blocks."
 
-    anchor_state: State | None = None
+    anchor_state: State = Field(default_factory=generate_pre_state)
     """
     The initial consensus state before processing.
 
-    If not provided, the framework will use the genesis fixture.
+    Defaults to the standard genesis state.
     """
 
     block: BlockSpec = Field(exclude=True)
@@ -101,9 +102,6 @@ def make_fixture(self) -> VerifySignaturesTest:
         Raises:
             AssertionError: If signature verification fails unexpectedly.
         """
-        # Ensure anchor_state is set
-        assert self.anchor_state is not None, "anchor state must be set before making the fixture"
-
         # Use shared key manager
         key_manager = XmssKeyManager.shared()
 
@@ -264,7 +262,6 @@ def _apply_tamper(self, signed_block: SignedBlock) -> SignedBlock:
             attestations = body.attestations.data
             if len(attestations) < 2:
                 raise ValueError("swap_first_two_attestations requires at least two attestations")
-            assert self.anchor_state is not None
 
             key_manager = XmssKeyManager.shared()
             original_attestation_proofs = [
diff --git a/packages/testing/src/framework/pytest_plugins/filler.py b/packages/testing/src/framework/pytest_plugins/filler.py
index f872e1133..315dea4d0 100644
--- a/packages/testing/src/framework/pytest_plugins/filler.py
+++ b/packages/testing/src/framework/pytest_plugins/filler.py
@@ -8,7 +8,6 @@
 from typing import Any
 
 import pytest
-from consensus_testing import generate_pre_state
 from consensus_testing.forks import FORKS_BY_NAME
 from consensus_testing.test_fixtures import (
     ApiEndpointTest,
@@ -341,22 +340,6 @@ def test_case_description(request: pytest.FixtureRequest) -> str:
     return combined_docstring
 
 
-@pytest.fixture(scope="function")
-def pre(request: pytest.FixtureRequest, fork: Any) -> Any:
-    """
-    Default consensus pre-state.
-
-    Tests can request this fixture to customize the initial state,
-    or omit it to use the default (auto-injected by framework).
-    """
-    spec = fork.spec_class()()
-
-    if hasattr(request, "param"):
-        return generate_pre_state(fork=spec, **request.param)
-
-    return generate_pre_state(fork=spec)
-
-
 def base_spec_filler_parametrizer(fixture_class: Any) -> Any:
     """
     Generate pytest.fixture for a given fixture class.
@@ -376,7 +359,6 @@ def base_spec_filler_parametrizer_func(
         request: pytest.FixtureRequest,
         fork: Any,
         test_case_description: str,
-        pre: Any,  # Auto-inject pre fixture
     ) -> Any:
         """Fixture used to instantiate an auto-fillable fixture object."""
 
@@ -384,15 +366,6 @@ class FixtureWrapper(fixture_class):
             """Wrapper class that auto-fills and collects fixtures on instantiation."""
 
             def __init__(self, **kwargs: Any) -> None:
-                # Auto-inject pre-state if not provided by test
-                if "pre" not in kwargs and "anchor_state" not in kwargs:
-                    # Determine which field to inject based on fixture type
-                    if hasattr(fixture_class, "__annotations__"):
-                        if "pre" in fixture_class.__annotations__:
-                            kwargs["pre"] = pre
-                        elif "anchor_state" in fixture_class.__annotations__:
-                            kwargs["anchor_state"] = pre
-
                 super().__init__(**kwargs)
 
                 filled_fixture = self.make_fixture()
diff --git a/src/lean_spec/spec/crypto/xmss/__init__.py b/src/lean_spec/spec/crypto/xmss/__init__.py
index aa19e1b20..4ecaedee3 100644
--- a/src/lean_spec/spec/crypto/xmss/__init__.py
+++ b/src/lean_spec/spec/crypto/xmss/__init__.py
@@ -10,6 +10,11 @@
 
 from lean_multisig_py import setup_prover
 
+# Why: break the import cycle between the signature and fork containers.
+# The signature containers need the fork slot type, while the fork
+# aggregation containers import the signature containers back.
+# Loading the forks package first lets the cycle resolve from any entry point.
+import lean_spec.spec.forks  # noqa: F401
 from lean_spec.config import LEAN_ENV
 from lean_spec.spec.crypto.xmss.containers import PublicKey, SecretKey
 from lean_spec.spec.crypto.xmss.interface import TARGET_SIGNATURE_SCHEME, GeneralizedXmssScheme
diff --git a/tests/consensus/lstar/fc/test_block_attestation_limits.py b/tests/consensus/lstar/fc/test_block_attestation_limits.py
index dde40984b..20eb5ee63 100644
--- a/tests/consensus/lstar/fc/test_block_attestation_limits.py
+++ b/tests/consensus/lstar/fc/test_block_attestation_limits.py
@@ -8,7 +8,6 @@
     ForkChoiceStep,
     ForkChoiceTestFiller,
     StoreChecks,
-    generate_pre_state,
 )
 from consensus_testing.keys import XmssKeyManager
 
@@ -99,7 +98,6 @@ def test_block_with_maximum_attestations(
     )
 
     fork_choice_test(
-        anchor_state=generate_pre_state(),
         steps=chain,
     )
 
@@ -175,6 +173,5 @@ def test_block_exceeding_maximum_attestations_is_rejected(
     )
 
     fork_choice_test(
-        anchor_state=generate_pre_state(),
         steps=chain,
     )
diff --git a/tests/consensus/lstar/state_transition/test_block_processing.py b/tests/consensus/lstar/state_transition/test_block_processing.py
index 9b848f318..64c49538c 100644
--- a/tests/consensus/lstar/state_transition/test_block_processing.py
+++ b/tests/consensus/lstar/state_transition/test_block_processing.py
@@ -37,7 +37,6 @@ def test_process_first_block_after_genesis(
     This is the foundation for all subsequent blocks.
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1)),
         ],
@@ -70,7 +69,6 @@ def test_linear_chain_multiple_blocks(
     5. Final state at slot 5
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
@@ -114,7 +112,6 @@ def test_blocks_with_gaps(
     This validates resilience to gaps.
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(4), parent_label="block_1", label="block_4"),
@@ -150,7 +147,6 @@ def test_block_at_large_slot_number(
     4. State remains consistent
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(100)),
         ],
@@ -182,7 +178,6 @@ def test_block_at_very_large_slot_with_many_skipped(
     5. No integer overflow or memory issues
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(500)),
         ],
@@ -225,7 +220,6 @@ def test_block_with_invalid_proposer(
     # - expected proposer is Uint64(1),
     # - we'll try to use Uint64(5) instead
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(
                 slot=Slot(1),
@@ -263,7 +257,6 @@ def test_block_with_invalid_parent_root(
     Without this check, attackers could create invalid chain branches.
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(
                 slot=Slot(1),
@@ -299,7 +292,6 @@ def test_block_with_invalid_state_root(
     This is a critical validation - without it, proposers could claim any arbitrary state.
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(
                 slot=Slot(1),
@@ -377,7 +369,6 @@ def test_block_extends_deep_chain(
     )
 
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=blocks,
         post=StateExpectation(slot=Slot(20)),
     )
@@ -419,7 +410,6 @@ def test_empty_blocks(
     ]
 
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=blocks,
         post=StateExpectation(
             slot=Slot(6), latest_block_header_slot=Slot(6), historical_block_hashes_count=6
@@ -451,7 +441,6 @@ def test_empty_blocks_with_missed_slots(
 
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), body=None, parent_label="block_1", label="block_2"),
diff --git a/tests/consensus/lstar/state_transition/test_finalization.py b/tests/consensus/lstar/state_transition/test_finalization.py
index 42e13c707..7d851128a 100644
--- a/tests/consensus/lstar/state_transition/test_finalization.py
+++ b/tests/consensus/lstar/state_transition/test_finalization.py
@@ -45,7 +45,6 @@ def test_finalization_on_next_justifiable_step(
     7. There are no pending justifications
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -120,7 +119,6 @@ def test_pending_justification_survives_finalization_rebase(
     8. justifications_validators contains a single 1-of-4 pending tally
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -307,7 +305,6 @@ def test_mid_block_finalized_slot_visibility(
     7. There are no pending justifications
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
@@ -405,7 +402,6 @@ def test_finalization_prunes_stale_pending_votes_and_rebases_window(
     7. There are no pending justifications
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -513,7 +509,6 @@ def test_stale_finalized_source_justifies_without_rewinding_finalization(
     5. There are no pending justifications
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -640,7 +635,6 @@ def test_source_at_finalized_boundary_justifies_without_refinalizing(
     5. There are no pending justifications
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -767,7 +761,6 @@ def test_non_adjacent_justification_finalizes_across_non_justifiable_gap(
     7. There are no pending justifications
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
@@ -848,7 +841,6 @@ def test_no_finalization_when_rebased_boundary_exposes_intermediate_justifiable_
     7. There are no pending justifications
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
@@ -973,7 +965,6 @@ def test_mid_block_finalized_slot_rejects_target_that_loses_justifiability(
     7. There are no pending justifications
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -1079,7 +1070,6 @@ def test_merged_attestations_for_same_target_justify_and_finalize_cleanly(
     7. There are no pending justifications
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -1164,7 +1154,6 @@ def test_rebased_finalization_prunes_stale_votes_and_preserves_future_votes(
     8. justifications_validators contains a single 1-of-4 pending tally
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
diff --git a/tests/consensus/lstar/state_transition/test_genesis.py b/tests/consensus/lstar/state_transition/test_genesis.py
index f2976a335..d4da3f4be 100644
--- a/tests/consensus/lstar/state_transition/test_genesis.py
+++ b/tests/consensus/lstar/state_transition/test_genesis.py
@@ -71,7 +71,6 @@ def test_genesis_default_configuration(
     - 4 validators with zero public_keys
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[],
         post=StateExpectation(
             slot=Slot(0),
diff --git a/tests/consensus/lstar/state_transition/test_justification.py b/tests/consensus/lstar/state_transition/test_justification.py
index 07ec8ee7d..46a45d56a 100644
--- a/tests/consensus/lstar/state_transition/test_justification.py
+++ b/tests/consensus/lstar/state_transition/test_justification.py
@@ -41,7 +41,6 @@ def test_supermajority_attestations_justify_block(
     4. latest_justified_slot advances to slot 1
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -256,7 +255,6 @@ def test_repeated_validators_do_not_double_count_across_blocks(
     4. latest_justified_slot stays at genesis
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -388,7 +386,6 @@ def test_pronic_boundary_acceptance(
     4. latest_justified_slot advances to slot 6
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
@@ -442,7 +439,6 @@ def test_non_justifiable_boundary_rejection(
     4. latest_justified_slot stays at genesis
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
@@ -497,7 +493,6 @@ def test_square_boundary_acceptance(
     4. latest_justified_slot advances to slot 9
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
@@ -724,7 +719,6 @@ def test_supermajority_with_mismatched_target_root_is_ignored(
     3. latest_justified_slot stays at genesis
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
@@ -776,7 +770,6 @@ def test_attestation_with_target_root_not_in_historical_hashes_is_skipped(
     4. latest_justified_slot stays at genesis
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -921,7 +914,6 @@ def test_target_at_or_before_source_is_ignored(
     4. latest_justified_slot remains at slot 4
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -1042,7 +1034,6 @@ def test_attestation_with_already_justified_target_is_silently_skipped(
     4. The block containing the duplicate attestation is accepted as valid
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             # Step 1 — Build chain and justify slot X
             BlockSpec(slot=Slot(1), label="block_1"),
@@ -1128,7 +1119,6 @@ def test_attestation_with_zero_hash_source_root_is_skipped(
     What matters for client teams: correct post-state, no crash.
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -1206,7 +1196,6 @@ def test_attestation_with_zero_hash_target_root_is_skipped(
     The test proves correct post-state regardless of which fires.
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(
@@ -1288,7 +1277,6 @@ def test_attestation_with_unjustified_source_is_silently_skipped(
     The 4-entry pending votes (not 8) proves it was skipped.
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             # Justify slot 1: 3/4 validators attest.
@@ -1410,7 +1398,6 @@ def test_same_block_multi_target_attestations_advance_to_highest_slot(
     since slot 9 is later in chain history.
     """
     state_transition_test(
-        pre=generate_pre_state(),
         blocks=[
             BlockSpec(slot=Slot(1), label="block_1"),
             BlockSpec(slot=Slot(2), parent_label="block_1", label="block_2"),
diff --git a/tests/consensus/lstar/verify_signatures/test_index_out_of_range.py b/tests/consensus/lstar/verify_signatures/test_index_out_of_range.py
index 96496a58f..c83a18919 100644
--- a/tests/consensus/lstar/verify_signatures/test_index_out_of_range.py
+++ b/tests/consensus/lstar/verify_signatures/test_index_out_of_range.py
@@ -5,7 +5,6 @@
     AggregatedAttestationSpec,
     BlockSpec,
     VerifySignaturesTestFiller,
-    generate_pre_state,
 )
 
 from lean_spec.spec.forks import Slot, ValidatorIndex
@@ -42,7 +41,6 @@ def test_attestation_validator_index_out_of_range_rejected(
       so the failure reason is unambiguous across clients.
     """
     verify_signatures_test(
-        anchor_state=generate_pre_state(),
         block=BlockSpec(
             slot=Slot(2),
             attestations=[