Modified bus scheduling problem in ortools

I want to modify the bus scheduling problem from ortools so as each driver's shift to be consecutive in terms of slots and drivers can share a shift at the same time if needed.

For example, assuming that we have the following half-hour shifts:

shifts = [
[0, '07:00', '07:30', 420, 450, 30],
[1, '07:30', '08:00', 450, 480, 30],
[2, '08:00', '08:30', 480, 510, 30],
[3, '08:30', '09:00', 510, 540, 30],
[4, '09:00', '09:30', 540, 570, 30],
[5, '09:30', '10:00', 570, 600, 30],
[6, '10:00', '10:30', 600, 630, 30],
[7, '10:30', '11:00', 630, 660, 30],
[8, '11:00', '11:30', 660, 690, 30],
[9, '11:30', '12:00', 690, 720, 30],
[10, '12:00', '12:30', 720, 750, 30],
[11, '12:30', '13:00', 750, 780, 30],
[12, '13:00', '13:30', 780, 810, 30],
[13, '13:30', '14:00', 810, 840, 30],
[14, '14:00', '14:30', 840, 870, 30],
[15, '14:30', '15:00', 870, 900, 30],
[16, '15:00', '15:30', 900, 930, 30],
[17, '15:30', '16:00', 930, 960, 30],
[18, '16:00', '16:30', 960, 990, 30],
[19, '16:30', '17:00', 990, 1020, 30],
[20, '17:00', '17:30', 1020, 1050, 30],
[21, '17:30', '18:00', 1050, 1080, 30],
[22, '18:00', '18:30', 1080, 1110, 30],
[23, '18:30', '19:00', 1110, 1140, 30],
[24, '19:00', '19:30', 1140, 1170, 30],
[25, '19:30', '20:00', 1170, 1200, 30],
[26, '20:00', '20:30', 1200, 1230, 30],
[27, '20:30', '21:00', 1230, 1260, 30],
[28, '21:00', '21:30', 1260, 1290, 30],
[29, '21:30', '22:00', 1290, 1320, 30],
[30, '22:00', '22:30', 1320, 1350, 30],
[31, '22:30', '23:00', 1350, 1380, 30],
[32, '23:00', '23:30', 1380, 1410, 30],
[33, '23:30', '24:00', 1410, 1440, 30]

]

I successfully execute the this version of the bus_scheduling code and I find that I need 2 drivers to satisfy the needs for the above mentioned schedule. The range of working hours is from 07:00 am to 24:00 (midnight).

As a result, if we have 2 bus drivers for this schedule, I would accept an allocation that covers the daily duty based on 12-h driver shift as following:

Driver 1: 07:00 - 19:00 with a break at 13:00
Driver 2: 12:00 - 24:00 with a break at 14:00 (basically no overlap with Driver 1's break)

What I mean by consecutive hours is that solutions that satisfy a 12-h driver shift solution in the form of 07:00-11:00 + 14:00-15:00 + 17:00-24:00 should not be acceptable.

I got an answer at the or-tools discussion saying that I need to maintain at each node the total time since the start of the shift, but I'm having difficulty in coding that assuming it solves my question.

from Modified bus scheduling problem in ortools