I'll write a quick update during my break.
I've finished the logic for the life-support modules. As long as there are active modules and they can support the crew, everything is quiet. Each in-game day, one unit of life-support supplies is consumed for each person aboard. Things get more interesting when something goes wrong.
When the total capacity of the systems is exceeded, they start raising alarms. Living conditions for crew and passengers deteriorate. Once a certain threshold is reached, the systems can no longer handle the load and automatically try to start backup or emergency life support, if such systems are aboard and operational. If the situation isn't resolved, some crew members may die. If the operating systems can support the survivors, conditions improve. If capacity is sufficient but supplies are running low, the system issues a warning. The ship will automatically head for the nearest port. At a critical warning, it will enter bubble mode, send an SOS, and request either crew rescue or delivery of supplies. This will happen regardless of the player's orders. The crew are saving their own lives and don't care about the boss's foolishness. In some cases, the player can still force the crew to continue flying and face death, but that's another matter. It would require a military ship, certain customs and rules in the colony, and particular training and morale among the crew.
Also, if there's no crew aboard, whether the ship is in port, in a parking orbit, or has been abandoned after a death or departure, all life-support systems enter standby. This preserves them, saves a great deal of power, and avoids consuming supplies.
Break's over; back to work. I'll build the crew and passenger module next. Or perhaps cargo. We'll see.