The device inside the packet was smaller than she’d expected: a wafer-thin disk, matte black, with a single, unobtrusive LED and a whisper of engraved text — BBM 22001. It fit in the palm of her hand like a coin from some future mint. Ada was a repair technician by trade: she coaxed life back into things people had given up on, and she had an instinctive respect for objects that seemed like they’d been designed to vanish. She slid BBM 22001 into the back of her worn toolkit and thought nothing of it for two days.

Outside, at dusk, a single streetlight blinked on. Its light was small and sufficient. Someone down the block paused under it and looked up at the sky, thinking of a song they had once sung. In the dark between the buildings, the world kept its small combustions of memory alive, and the last light — when tended — never quite went out.

Ada could have closed the window and stowed the device in a drawer. Instead, she carried it to the small park across the street where an old woman fed pigeons. The woman’s hands were thin as paper and full of knuckles the color of tea. Ada sat beside her and, without thinking, asked, “If you could live in one memory forever, which would you choose?”