The Hidden Cost of Going Back
■ The word undo carries two very different meanings here
On a screen, undo is nearly free: delete the input, restore the previous state. Said to a robot, the same word splits in two. Cancel the request, or reverse the motion already made? Hakobukun chose the second and drove the whole route backwards.
■ In the physical world, reversing is itself a new action
For half a minute the corridor clears, the reverse alarm sounds, and people flatten against the walls. The cancelled errand is spending real time and space in order to be cancelled. Undo did not subtract work here. It added a second job.
■ Conclusion: Decide the scope of undo before shipping it
Stopping where it stood was all anyone needed. Split cancellation from reversal into two separate commands, and let the person choose which one runs. If they cannot choose, make stopping the default. Leave the word to the machine and the ward pays.
Say erase, and the machine goes to erase it.
