Modify rows in a 2d array so that datetime stamps are contiguous

I have a 2d array of jobs and each job contains a start time, an end time which is always 60 minutes after the start time, then an "add" value which is the number of minutes until the next job should start.

I need to adjust all rows so that each start time is the previous job's end time plus its "add" time.

Here is a sample array:

[
    [
        'id' => 9,
        'needed_at' => '2023-02-26 03:31:04',
        'ended_at' => '2023-02-26 04:31:04',
        'add' => 20
    ],
    [
        'id' => 6,
        'needed_at' => '2023-02-26 04:51:04',
        'ended_at' => '2023-02-26 05:51:04',
        'add' => 30
    ],
    [
        'id' => 7,
        'needed_at' => '2023-02-26 09:21:04',
        'ended_at' => '2023-02-26 10:21:04',
        'add' => 30
    ]
]

My desired result:

[
    [
        'id' => 9,
        'needed_at' => '2023-02-26 03:31:04',
        'ended_at' => '2023-02-26 04:31:04',
        'add' => 20
    ],
    [
        'id' => 6,
        'needed_at' => '2023-02-26 04:51:04',
        'ended_at' => '2023-02-26 05:51:04',
        'add' => 30
    ],
    [
        'id' => 7,
        'needed_at' => '2023-02-26 06:21:04',  # changed based on id 6 data
        'ended_at' => '2023-02-26 07:21:04',   # changed based on new need_at time of this row
        'add' => 30                            # not actually used because no next job
    ]
]

What I have tried is:

foreach ($jobs as $k => $j) {
    $s = $k+1;
    $date = new \DateTimeImmutable($j->ended_at);
    $add = $j->add;
    $date_new = $date->modify('+'.$add.' minutes');
    $needed_at = $date_new->format('Y-m-d H:i:s');
    $data['needed_at'] = $needed_at;
    
    $date2 = new \DateTimeImmutable($needed_at);
    $ended_at = $date2->modify('+60 minutes');
    $data['ended_at'] = $ended_at->format('Y-m-d H:i:s');
    $d[]=[
        'id' => $jobs[$s]->id,
        'needed_at' => $needed_at,
        'ended_at' => $data['ended_at'],
        'add' => $add
    ];
}

It is not working. Is it possible to use first iteration modified data into second iteration?

Since the first element of the array will not change we excluded from the loop.

Two elements are important to get the expected output : ended_at and add, then after each iteration those variables will take the current values and so on

$format = 'Y-m-d H:i:s';

$ended_at = $jobs[0]['ended_at'];
$add = $jobs[0]['add'];

$d[0] = $jobs[0];
foreach($jobs as $k => $j){
       if ($k < 1) continue;
       
       $ended_at = DateTimeImmutable::createFromFormat($format, $ended_at);
       
       $ended = $ended_at->modify('+'.$add.' minutes');
       $needed = $ended->modify('+60 minutes');
       
       $ended = $ended->format($format);
       $needed = $needed->format($format);
       
       $d[]=array(
         'id' => $jobs[$k]['id'],
         'needed_at' => $ended,
         'ended_at' => $needed,
         'add' => $jobs[$k]['add']
       );
       
       $ended_at = $needed;
       $add = $jobs[$k]['add'];
       
}

print_r($d);

Demo here