Essay 02
The line is the record.
The long window on the rail is not a decoration. It is the only place a request is allowed to become readable.
A program can prepare a request and display its own summary. That summary is convenient and it is also untrusted. The chip receives the request over USB-C and paints its own version on the horizontal line. Amount, destination, and any warning the chip wants to raise are part of that painting.
The teal slit along the top edge lights while this is happening. It marks the rail as the object that is awake. It does not talk to a phone, a network, or another rail.
You move through the line with the square key. If a word is wrong, you clear it. The silver dial is for the moment the line matches what you meant. A signature is produced only then, and the key that produced it stays behind the glass.