At 3:17 a.m., Fang Cheng woke up right on time. He opened the laptop on his bedside table. Its blue light reflected on his face like the shadowless lamp in an operating room. In the Excel spreadsheet, the progress bar for Day 107 read: 99.7%. He typed a line in the notes column: "No anomalies today." Then he got up, measured out 250 milliliters of water, and poured it into the electric kettle.
