@@ -0,0 +1,56 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+import multiprocessing
+import os
+import subprocess
+import sys
+
+import pytest
+
+# Runs in a fresh interpreter so the forked parent is small and holds only what the
+# scenario creates, not whatever earlier tests left in the pytest worker.
+_PREVIEW_IN_FORKED_CHILD = """
+import multiprocessing
+import sys
+
+import data_designer.config as dd
+from data_designer.interface import DataDesigner
+
+
+def preview():
+    builder = dd.DataDesignerConfigBuilder()
+    builder.add_column(
+        dd.SamplerColumnConfig(
+            name="category",
+            sampler_type=dd.SamplerType.CATEGORY,
+            params=dd.CategorySamplerParams(values=["a", "b", "c"]),
+        )
+    )
+    assert len(DataDesigner().preview(builder, num_records=3).dataset) == 3
+
+
+preview()  # the parent starts DataDesigner's background event loop
+child = multiprocessing.get_context("fork").Process(target=preview)
+child.start()
+child.join(timeout=30)
+if child.is_alive():
+    child.kill()
+    child.join()
+    sys.exit("forked child hung in preview()")
+sys.exit(child.exitcode)
+"""
+
+
+@pytest.mark.skipif("fork" not in multiprocessing.get_all_start_methods(), reason="requires the fork start method")
+def test_preview_in_child_forked_after_parent_preview() -> None:
+    result = subprocess.run(
+        [sys.executable, "-c", _PREVIEW_IN_FORKED_CHILD],
+        capture_output=True,
+        text=True,
+        timeout=120,
+        env={**os.environ, "NEMO_TELEMETRY_ENABLED": "false"},
+    )
+    assert result.returncode == 0, f"preview() in a forked child failed:\n{result.stderr[-4000:]}"