fix: preserve seeded IVF-PQ training contracts

python/python/lancedb/table.py

@@ -2762,6 +2762,11 @@ class LanceTable(Table):
             if config is not None and hasattr(config, "accelerator"):
                 acc = getattr(config, "accelerator", None)
                 if acc is not None:
+                    if isinstance(config, IvfPq) and config.seed is not None:
+                        raise ValueError(
+                            "IvfPq seed is not supported with accelerator-based "
+                            "index training"
+                        )
                     # Dispatch to pylance for GPU acceleration
                     index_type_map = {
                         "IvfFlat": "IVF_FLAT",

python/python/tests/test_index.py

@@ -26,7 +26,7 @@ from lancedb.index import (
     HnswFlat,
     FTS,
 )
-from lancedb.table import IndexStatistics
+from lancedb.table import IndexStatistics, LanceTable
 
 
 @pytest_asyncio.fixture
@@ -399,6 +399,11 @@ def test_seeded_ivfpq_rejects_accelerator():
     with pytest.raises(ValueError, match="seed is not supported with accelerator"):
         IvfPq(seed=42, accelerator="cuda")
 
+    config = IvfPq(seed=42)
+    config.accelerator = "cuda"
+    with pytest.raises(ValueError, match="seed is not supported with accelerator"):
+        object.__new__(LanceTable).create_index("vector", config=config)
+
 
 @pytest.mark.asyncio
 async def test_create_ivfrq_index(some_table: AsyncTable):