The first document to give the fault a name had been written before Yansheng arrived in Kenya.
It was a work ticket from October 23, raised after a cooling transfer failed to return automatically to its usual configuration. The field was marked recurring condition. Beneath it a technician had typed AUX-RETURN-04, followed by a description of a relay that sometimes held its commanded state after the load step ended.
Yanchuan read the identifier twice. It was the closest thing to a physical cause that their months of correspondence had produced.
Amina had obtained the ticket through the authorized technical review. The copy contained the equipment designation, observations, and unresolved action. It did not include worker contact details or unrelated maintenance history.
“Was Daniel the technician?” he asked.
“He saw the temporary arrangement before his accident,” Amina said. “This entry was raised by another shift. Don’t attach his injury to a fault because he also spoke about it.”
“I wasn’t going to.”
“You were halfway through the question.”
He admitted she was right. Daniel’s injury had occurred during handling work on October 24. The ticket was dated the day before. The dates mattered because Yanchuan’s mind was already drawing one line through every event that frightened him.
Han Rui joined their technical call later. He asked for the failure description rather than the code.
“A name doesn’t diagnose a fault,” he said. “Someone can call anything a relay problem.”
They worked through the sequence: a cooling load was transferred temporarily between supplies; a command instructed it to return; one status field reported the command as complete, while an independent indicator showed the load still served by the temporary path. The work ticket required confirmation of the physical state before closing the task.
“That would explain why a restore sign-off matters,” Yanchuan said.
“It explains why the sign-off exists in the procedure,” Han replied. “We haven’t measured that machine ourselves.”
The difference took up a single sentence in the report. It took Yanchuan half an hour to accept.
At work, Chen asked him to examine a fault-classification product being proposed for the factory’s maintenance team. The supplier’s demonstration promised that an intelligent system would sort thousands of alerts and identify the most likely cause before a technician reached the machine.
The sample looked impressive. An alert labeled pump vibration was matched to a bearing problem, with a probability printed to two decimal places. A second alert went to motor alignment. A third, drawn from an old training case, showed a temperature increase and suggested cooling failure.
Yanchuan asked what information the model had not seen.
The salesman said its training data included years of maintenance reports and sensor histories. Yanchuan asked whether unresolved tickets appeared in that data with their final outcome or merely with the description someone had entered when they closed the screen.
The salesman checked the documentation.
“We exclude incomplete records,” he said.
“Then you may be excluding the failures that were hardest to resolve.”
The man looked annoyed, but Chen asked him to write down the limitation. They would still consider the system; an incomplete data set did not make every prediction useless. It did mean that accuracy on clean historical cases could not be sold as proof of reliability under the uncertain conditions the technicians actually faced.
After the demonstration Chen passed Yanchuan a small notebook.
“Don’t let the missing-person case turn every machine into your brother’s machine,” he said. “But don’t stop asking that question about missing records.”
Yanchuan placed the notebook beside his laptop. He had stopped knowing whether his ordinary expertise was becoming sharper or simply less patient.
The next message from Kenya answered part of the maintenance question. A later ticket referenced AUX-RETURN-04 as a condition requiring manual verification during the October 29 acceptance run. The final package stated that all listed conditions had been satisfied. It contained no attached evidence that the independent status had been checked after the temporary transfer.
Mei reviewed the document and found no basis to call the status false. The final text could reflect a missing attachment, a mistaken closure, or an approval whose evidence was retained in another system.
“And it could reflect someone treating a command as a result,” she said.
“That’s the second possibility.”
“It’s one possibility. Don’t let us give it a number because it feels neat.”
That night, Yanchuan added the identifier to the family’s technical index. He gave it a separate page from the missing-person chronology. The case needed investigators to ask where a man went; the technical inquiry needed engineers to ask how a circuit behaved. The two questions might eventually meet, but neither could answer the other by resemblance alone.
An called during dinner. Their son had developed a cough, and the school asked families to keep children with symptoms at home. She had spent the day rearranging client visits. Yanchuan began offering solutions before she finished.
“I’m telling you why I was late replying,” she said. “I’m not asking you to run tomorrow from Shenzhen.”
He apologized and asked how the boy was sleeping.
“Loudly,” she said. “Like his father.”
The line surprised them both. An did not take it back.
After they spoke, Yanchuan imagined Yansheng dealing with a stubborn relay in a hot room, irritated by a report that said a command had completed what nobody had looked at. The picture felt true because it was ordinary enough to fit his brother.
It remained an imagined picture.
He opened the message Yansheng had sent in October: Can these two summaries both be right?
For the first time, Yanchuan could give a more precise answer. Under different accounting boundaries, perhaps. For the same promised operating condition, not without an explanation of the missing load and the unfinished restoration check.
He wrote that conclusion for the reviewers, with the ticket references and three possible explanations. He did not write that the fault had caused a disappearance.
The identifier stayed at the top of the technical page. It gave the failure a name.
He checked that the request for the original handover record had reached the reviewer. The status column said pending. He did not change it.