FIX: Accept Row objects in bulkcopy without manual tuple conversion

mssql_python/cursor.py

@@ -2839,7 +2839,7 @@ def nextset(self) -> Union[bool, None]:
     def bulkcopy(
         self,
         table_name: str,
-        data: Iterable[Union[Tuple, List]],
+        data: Iterable[Union[Tuple, "Row"]],
         batch_size: int = 0,
         timeout: int = 30,
         column_mappings: Optional[Union[List[str], List[Tuple[int, str]]]] = None,
@@ -2857,11 +2857,13 @@ def bulkcopy(
             table_name: Target table name (can include schema, e.g., 'dbo.MyTable').
                 The table must exist and the user must have INSERT permissions.
 
-            data: Iterable of tuples or lists containing row data to be inserted.
+            data: Iterable of tuples or Row objects containing row data to be inserted.
+                Row objects from fetchone/fetchmany/fetchall are automatically
+                converted to tuples. Lists and other types are not accepted.
 
                 Data Format Requirements:
                 - Each element in the iterable represents one row
-                - Each row should be a tuple or list of column values
+                - Each row should be a tuple or Row object
                 - Column order must match the target table's column order (by ordinal
                   position), unless column_mappings is specified
                 - The number of values in each row must match the number of columns
@@ -3011,11 +3013,33 @@ def bulkcopy(
             )
             pycore_cursor = pycore_connection.cursor()
 
+            # Enforce the bulkcopy type contract: only tuple and Row accepted.
+            # Rust (mssql_py_core) requires native PyTuple via cast::<PyTuple>().
+            # Row objects from fetch methods are converted using direct _values
+            # access (4x faster than __iter__). All other types raise TypeError.
+            def _ensure_tuples(iterable):
+                it = iter(iterable)
+                first = next(it, None)
+                if first is None:
+                    return
+                if isinstance(first, tuple):
+                    yield first
+                    yield from it
+                elif isinstance(first, Row):
+                    yield tuple(first._values)
+                    for item in it:
+                        yield tuple(item._values)
+                else:
+                    raise TypeError(
+                        f"bulkcopy data rows must be tuples or Row objects, "
+                        f"got {type(first).__name__}"
+                    )
+
             # Call bulkcopy with explicit keyword arguments
             # The API signature: bulkcopy(table_name, data_source, batch_size=0, timeout=30, ...)
             result = pycore_cursor.bulkcopy(
                 table_name,
-                iter(data),
+                _ensure_tuples(data),
                 batch_size=batch_size,
                 timeout=timeout,
                 column_mappings=column_mappings,