diff --git a/openagent_eval/core/__init__.py b/openagent_eval/core/__init__.py
index 46c1cf0..c92fb03 100644
--- a/openagent_eval/core/__init__.py
+++ b/openagent_eval/core/__init__.py
@@ -1,8 +1,16 @@
 """Core module for OpenAgent Eval."""
 
-from openagent_eval.core.engine import Engine
+from openagent_eval.core.engine import Engine, EvaluationReport
 from openagent_eval.core.executor import Executor
-from openagent_eval.core.pipeline import Pipeline
+from openagent_eval.core.pipeline import EvaluationResult, Pipeline, PipelineResult
 from openagent_eval.core.registry import Registry
 
-__all__ = ["Engine", "Executor", "Pipeline", "Registry"]
+__all__ = [
+    "Engine",
+    "EvaluationReport",
+    "EvaluationResult",
+    "Executor",
+    "Pipeline",
+    "PipelineResult",
+    "Registry",
+]
diff --git a/tests/unit/test_core/test_exports.py b/tests/unit/test_core/test_exports.py
new file mode 100644
index 0000000..117e253
--- /dev/null
+++ b/tests/unit/test_core/test_exports.py
@@ -0,0 +1,58 @@
+"""Tests for the public import surface of ``openagent_eval.core``.
+
+Regression guard for #55: every name in ``core.__all__`` must be importable
+directly from the package, not only from its defining submodule, and must be
+the exact same object as the one defined there (no accidental shadowing or
+copying).
+"""
+
+from __future__ import annotations
+
+import openagent_eval.core as core
+from openagent_eval.core.engine import Engine as EngineEngine
+from openagent_eval.core.engine import EvaluationReport as EngineEvaluationReport
+from openagent_eval.core.executor import Executor as ExecutorExecutor
+from openagent_eval.core.pipeline import EvaluationResult as PipelineEvaluationResult
+from openagent_eval.core.pipeline import Pipeline as PipelinePipeline
+from openagent_eval.core.pipeline import PipelineResult as PipelinePipelineResult
+from openagent_eval.core.registry import Registry as RegistryRegistry
+
+
+def test_all_lists_the_full_public_surface() -> None:
+    """``__all__`` must enumerate exactly the intended public names."""
+    assert set(core.__all__) == {
+        "Engine",
+        "EvaluationReport",
+        "EvaluationResult",
+        "Executor",
+        "Pipeline",
+        "PipelineResult",
+        "Registry",
+    }
+
+
+def test_every_name_in_all_is_importable() -> None:
+    """Every name in ``__all__`` must actually be a package attribute."""
+    for name in core.__all__:
+        assert hasattr(core, name), f"{name} listed in __all__ but not importable"
+
+
+def test_reexported_names_are_the_defining_objects() -> None:
+    """Every re-exported name must be the same object as its original."""
+    from openagent_eval.core import (
+        Engine,
+        EvaluationReport,
+        EvaluationResult,
+        Executor,
+        Pipeline,
+        PipelineResult,
+        Registry,
+    )
+
+    assert Engine is EngineEngine
+    assert EvaluationReport is EngineEvaluationReport
+    assert EvaluationResult is PipelineEvaluationResult
+    assert Executor is ExecutorExecutor
+    assert Pipeline is PipelinePipeline
+    assert PipelineResult is PipelinePipelineResult
+    assert Registry is RegistryRegistry