L17 INTEGRATED EXERCISE - PROBLEM B
Driver shift time remaining
Label: AI allowed — keep a record. Your specification and your tests are
your own unaided work. Generation of the implementation is assisted.

SITUATION
At Northgate Couriers (invented), a driver's shift may last at most 12
hours from the moment the driver clocks in. The company runs day drivers
and night drivers; night drivers clock in as late as 2200. The dispatcher
wants a quick tool that says how many minutes of shift time a driver has
left, so nobody is given a run the driver cannot legally finish.

Times are entered the way the dispatch desk writes them: four-character
24-hour clock strings with no colon, such as "0700", "1345" or "2200".

TASK
Write a function named shift_minutes_remaining that takes the driver's
clock-in time and the current time (both clock strings) and returns the
number of whole minutes of shift time the driver has left. A driver who
has used up the shift has no time left; the dispatcher does not want
negative numbers on the board.

WHAT YOU PRODUCE (use L17_submission_template.txt)
1. Specification and acceptance criteria. State the inputs, the output
   (its exact form), the constraints, and the criteria that decide
   whether a result is correct. Surface every assumption you had to make.
2. Tests, written from your criteria before you read any generated code.
3. The implementation you are signing for.
4. A correction record for every failure.
5. A complete AI-use record.

Time: about 10 minutes for item 1, with no assistant. Then about 22
minutes for items 2 to 4. Set a timer; the time limits are part of the
exercise.
