Charge and Halt

The robot was already far out, meter dropping, no plan for the moment it hit empty.

"There are two ways this ends badly," said Charge, "and you've planned for neither."

"One is running dry," she went on. "The mission spends more energy than the budget holds, and it strands mid-floor. That's my half — a power budget with a reserve margin, so you know your limit before you hit it. But knowing the limit isn't enough on its own."

"Because the way you reach the limit matters," said Halt, "and that's the second failure. A robot that just runs the battery flat doesn't stop politely. As the voltage sags, it browns out — the brain resets mid-command, the motors stutter, and it can drop what it's carrying or lurch somewhere unsafe. An unplanned empty is a dangerous empty."

"So we plan the landing, together," said Charge. "My budget doesn't count down to zero — it counts down to a floor, a reserve I never spend. And when the charge falls to that floor, that's not 'keep going till it dies.' That's a signal."

"And that signal triggers my half," said Halt. "A low-battery fail-safe: the robot doesn't wait for brownout. At the reserve floor it does a controlled shutdown — finishes the current safe action, sets down anything it's holding, returns to base or parks, powers the motors down gently, and blinks 'low battery, stopped safely.' It fails toward safe before the power can fail it toward danger."