diff --git a/test/test_fsm.py b/test/test_fsm.py
index 7b9855f..4026002 100644
--- a/test/test_fsm.py
+++ b/test/test_fsm.py
@@ -100,6 +100,10 @@ def fsm_node_table_setup(tmp_path: Path):
     conn.execute(
         f"COPY person FROM ['{LBUG_ROOT}/dataset/tinysnb/vPerson.csv', '{LBUG_ROOT}/dataset/tinysnb/vPerson2.csv'](ignore_errors=true, header=false)"
     )
+    # COPY no longer force-checkpoints when auto_checkpoint=false (fix for #755).
+    # Checkpoint explicitly so the data pages are on disk and storage_info()
+    # reports real page indices for the reclaim assertions below.
+    conn.execute("checkpoint")
     return db, conn
 
 
@@ -112,6 +116,7 @@ def fsm_rel_table_setup(fsm_node_table_setup):
     conn.execute(
         f"COPY knows FROM ['{LBUG_ROOT}/dataset/tinysnb/eKnows.csv', '{LBUG_ROOT}/dataset/tinysnb/eKnows_2.csv']"
     )
+    conn.execute("checkpoint")
     return fsm_node_table_setup
 
 
@@ -138,6 +143,7 @@ def fsm_rel_group_setup(tmp_path: Path):
     conn.execute(
         f'COPY likes FROM "{LBUG_ROOT}/dataset/rel-group/edge.csv" (FROM="personB", TO="personA");'
     )
+    conn.execute("checkpoint")
     return db, conn
 
 
@@ -193,6 +199,7 @@ def test_fsm_reclaim_node_table_recopy(fsm_node_table_setup) -> None:
     conn.execute(
         f"COPY person FROM ['{LBUG_ROOT}/dataset/tinysnb/vPerson.csv', '{LBUG_ROOT}/dataset/tinysnb/vPerson2.csv'](ignore_errors=true, header=false)"
     )
+    conn.execute("checkpoint")
     new_num_pages = get_total_used_pages(conn)
     assert prev_num_pages == new_num_pages
 
diff --git a/test/test_issue.py b/test/test_issue.py
index 5cea6b0..0faf62a 100644
--- a/test/test_issue.py
+++ b/test/test_issue.py
@@ -152,6 +152,49 @@ def test_issue_483_numpy_ndarray_parameter(conn_db_readwrite: ConnDB) -> None:
     result.close()
 
 
+def test_issue_866_repeated_parameterized_write_then_vector_read(
+    conn_db_readwrite: ConnDB,
+) -> None:
+    # https://github.com/LadybugDB/ladybug/issues/866
+    # Re-executing the same parameterized write query string through the implicit
+    # prepared-statement cache takes the cached-physical-plan fast path, whose
+    # prepareForReuse() calls FactorizedTable::clear() on the root ResultCollector of
+    # the write. Write statements return no columns, so that FactorizedTable has an
+    # empty schema and never allocates its block collections; clear() dereferenced
+    # the null collection (SIGSEGV on 0.20.0). The vector similarity query in the
+    # original report was unrelated to the crash.
+    conn, _ = conn_db_readwrite
+    conn.execute(
+        "CREATE NODE TABLE Contribution(id STRING, embedding FLOAT[4], PRIMARY KEY(id))"
+    )
+    embeddings = {
+        "c1": [1.0, 0.0, 0.2, 0.0],
+        "c2": [0.0, 1.0, 0.0, 0.2],
+        "c3": [0.8, 0.0, 0.1, 0.0],
+    }
+    # Same parameterized query string executed repeatedly (fast path on every run
+    # but the first).
+    for node_id, embedding in embeddings.items():
+        result = conn.execute(
+            "CREATE (:Contribution {id: $id, embedding: $embedding})",
+            {"id": node_id, "embedding": embedding},
+        )
+        result.close()
+
+    result = conn.execute(
+        "MATCH (c:Contribution) RETURN c.id, ARRAY_COSINE_SIMILARITY(c.embedding, [1.0, 0.0, 0.2, 0.0])"
+        " AS sim ORDER BY c.id"
+    )
+    assert result.has_next()
+    assert result.get_next() == ["c1", pytest.approx(1.0)]
+    assert result.has_next()
+    assert result.get_next() == ["c2", pytest.approx(0.0)]
+    assert result.has_next()
+    assert 0.0 < result.get_next()[1] < 1.0
+    assert not result.has_next()
+    result.close()
+
+
 # TODO(Maxwell): check if we should change getCastCost() for the following test
 # def test_issue_3248(conn_db_readwrite: ConnDB) -> None:
 #     conn, _ = conn_db_readwrite