Wire datetime_columns through query params and reads; add db_size and vacuum guard

tests/test_cache.py

@@ -288,3 +288,21 @@ def test_vacuum_in_memory_is_noop(cache, source_conn):
     cache.load_table("users", ["name"], source_conn)
     cache.vacuum(incremental=False)  # no-op, no error
     assert cache.is_table_cached("users") is True
+
+
+def test_incremental_vacuum_warns_without_incremental_auto_vacuum(tmp_path, source_conn):
+    """Incremental vacuum on a DB that isn't auto_vacuum=INCREMENTAL warns and skips."""
+    from loguru import logger
+
+    messages: list[str] = []
+    sink_id = logger.add(messages.append, level="WARNING", filter="sqlmem")
+    logger.enable("sqlmem")
+    try:
+        c = CacheManager(db_path=tmp_path / "c.db", backup_interval=9999, in_memory=False)
+        c.load_table("users", ["name"], source_conn)
+        c.vacuum(incremental=True)  # auto_vacuum defaults to NONE → no-op + warning
+        c.close()
+    finally:
+        logger.remove(sink_id)
+        logger.disable("sqlmem")
+    assert any("auto_vacuum" in m for m in messages)