diff --git a/test/unit/test_assembly.py b/test/unit/test_assembly.py
index beeafbc..5067110 100644
--- a/test/unit/test_assembly.py
+++ b/test/unit/test_assembly.py
@@ -578,6 +578,11 @@ def test_init_assembly_enforcement_mode_forwarded_to_client(
     mode: str,
 ) -> None:
     """All three valid EnforcementMode values land on the GatewayClient."""
+    # Force the pure-Python path so `enforce` does not trigger the AAASM-3402
+    # native gRPC registration (which would fail-closed without a live gateway).
+    # This keeps the test focused on enforcement-mode forwarding regardless of
+    # whether the native `_core` extension is built (AAASM-3435).
+    monkeypatch.setattr(core_assembly, "_native_core_available", lambda: False)
     monkeypatch.setattr(core_assembly, "_register_adapters", lambda **kwargs: [])
     monkeypatch.setattr(
         core_assembly,
diff --git a/test/unit/test_types_audit_event.py b/test/unit/test_types_audit_event.py
index 1c9f457..cb0fe64 100644
--- a/test/unit/test_types_audit_event.py
+++ b/test/unit/test_types_audit_event.py
@@ -11,6 +11,15 @@
 import pytest
 
 from agent_assembly import AuditEvent, CallStackNode
+from agent_assembly.core.runtime_interceptor import _native_core_available
+
+# The native `_core` extension implements the wire codec; these import-error
+# guards only fire in pure-Python mode where it is absent (AAASM-3435).
+_NATIVE_CORE_PRESENT = _native_core_available()
+_requires_no_native_core = pytest.mark.skipif(
+    _NATIVE_CORE_PRESENT,
+    reason="native `_core` is present; the import-error path only exists without it",
+)
 
 
 def test_call_stack_node_required_fields() -> None:
@@ -98,6 +107,7 @@ def test_top_level_imports_resolve_to_types_module() -> None:
     assert CallStackNode is TypesCallStackNode
 
 
+@_requires_no_native_core
 def test_to_wire_bytes_raises_helpful_import_error_without_native_core() -> None:
     """In pure-Python mode the native `_core` extension is absent, so the
     encode path raises ImportError with a maturin/reinstall hint."""
@@ -110,6 +120,7 @@ def test_to_wire_bytes_raises_helpful_import_error_without_native_core() -> None
     assert "maturin develop" in message
 
 
+@_requires_no_native_core
 def test_from_wire_bytes_raises_helpful_import_error_without_native_core() -> None:
     """The decode path raises the same kind of guidance when `_core` is absent."""
     with pytest.raises(ImportError) as exc_info: