ROW START/END columns added with ALTER TABLE are never INVISIBLE

MariaDB [test]> CREATE OR REPLACE TABLE t (

    ->     x INT PRIMARY KEY,

    ->     valid_since TIMESTAMP(6) AS ROW START INVISIBLE,

    ->     valid_until TIMESTAMP(6) AS ROW END INVISIBLE,

    ->     PERIOD FOR SYSTEM_TIME (valid_since, valid_until)

    -> )

    ->     WITH SYSTEM VERSIONING

    -> ;

Query OK, 0 rows affected (0.018 sec)

MariaDB [test]> INSERT INTO t (x) VALUES (1), (2), (3);

Query OK, 3 rows affected (0.001 sec)

Records: 3  Duplicates: 0  Warnings: 0

MariaDB [test]> SELECT * FROM t;

+---+

| x |

+---+

| 1 |

| 2 |

| 3 |

+---+

3 rows in set (0.000 sec)

MariaDB [test]> CREATE OR REPLACE TABLE t (

    ->     x INT PRIMARY KEY

    -> )

    ->     WITH SYSTEM VERSIONING

    -> ;

Query OK, 0 rows affected (0.020 sec)

MariaDB [test]> SET SESSION system_versioning_alter_history = KEEP;

Query OK, 0 rows affected (0.000 sec)

MariaDB [test]> ALTER TABLE t

    ->     ADD COLUMN valid_since TIMESTAMP(6) AS ROW START INVISIBLE,

    ->     ADD COLUMN valid_until TIMESTAMP(6) AS ROW END INVISIBLE,

    ->     ADD PERIOD FOR SYSTEM_TIME (valid_since, valid_until);

Query OK, 0 rows affected (0.019 sec)

Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> SET SESSION system_versioning_alter_history = ERROR;

Query OK, 0 rows affected (0.000 sec)

MariaDB [test]> INSERT INTO t (x) VALUES (1), (2), (3);

Query OK, 3 rows affected (0.001 sec)

Records: 3  Duplicates: 0  Warnings: 0

MariaDB [test]> SELECT * FROM t;

+---+----------------------------+----------------------------+

| x | valid_since                | valid_until                |

+---+----------------------------+----------------------------+

| 1 | 2025-06-15 15:51:54.185627 | 2106-02-07 06:28:15.999999 |

| 2 | 2025-06-15 15:51:54.185627 | 2106-02-07 06:28:15.999999 |

| 3 | 2025-06-15 15:51:54.185627 | 2106-02-07 06:28:15.999999 |

+---+----------------------------+----------------------------+

MariaDB [test]> SHOW CREATE TABLE t \G

*************************** 1. row ***************************

       Table: t

Create Table: CREATE TABLE `t` (

  `x` int(11) NOT NULL,

  `valid_since` timestamp(6) GENERATED ALWAYS AS ROW START,

  `valid_until` timestamp(6) GENERATED ALWAYS AS ROW END,

  PRIMARY KEY (`x`,`valid_until`),

  PERIOD FOR SYSTEM_TIME (`valid_since`, `valid_until`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci WITH SYSTEM VERSIONING