L17 INTEGRATED EXERCISE - PROBLEM C
Fuel state classification
Label: AI allowed — keep a record. Your specification and your tests are
your own unaided work. Generation of the implementation is assisted.

SITUATION
A facilities company (invented) looks after the diesel tank that feeds a
building's backup generator. Its tank-level sheet defines four fuel
states as a share of the tank's capacity:

    NORMAL      more than 40 percent of capacity
    LOW         40 percent of capacity or less
    MINIMUM     20 percent of capacity or less
    EMERGENCY   10 percent of capacity or less

Fuel quantity and tank capacity are both reported in litres. Level
sensors sometimes fail. The sheet says a reading below zero, or a reading
higher than the tank can hold, must be reported as SENSOR FAULT rather
than as a fuel state.

TASK
Write a function named fuel_state that takes the fuel reading and the
tank capacity and returns the fuel state as one of these exact strings:
"NORMAL", "LOW", "MINIMUM", "EMERGENCY", "SENSOR FAULT".

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.
