Two days.
He had said nothing changes in the final three days and he has been right: nothing has changed. The counter at relay four is at a number he has stopped noting. The relay node at position eight reads 94.7% and is still not updating. The self-portrait series at relay three is unchanged — the same eleven photographs in the same order, relay eight at the top right because he had put it there and had not moved it.
He walks the corridor on the second-to-last day the same way he has walked it for six months: from relay one toward relay seven, both sides of the center line, the pace that lets the relay nodes register his passage without flagging him as a maintenance event. He has learned this pace so well he no longer thinks about it. It is the pace the building expects. He has become predictable to the infrastructure.
At the witness log he stops. He has not read other people's entries since Mitsuki asked him to sign — he signed once, at relay six, during week two, when the project was still new enough that signing felt like a choice. He opens the glass panel. The notebook has three new pages he has not read. He reads the first entry. The handwriting is not Mitsuki's. It is someone else's — smaller, more deliberate, the handwriting of a person who considers each letter before making it. The entry says: if you were here but not here — I was here. I was always here. I just did not know the corridor was recording.
He reads it twice. He does not know who wrote it.
He closes the glass panel.
The corridor has been recording everyone who passes: Mitsuki's patients, Chae-Gyeol's double shift, the delivery schedules, the relay node data, the relay counter, his own eleven photographs. It has been recording the people who did not know they were being recorded. The entry in the witness log is from someone who has just learned this about themselves — and signed it. The corridor already has more of everyone in it than any of them put together.
At relay seven he steps into Euljiro for three minutes. The market is quieter at this hour. A few stalls, a man with a cart he does not rush because no one is rushing him. Bok stands on the pavement and looks back at the relay seven door. From outside, the corridor looks like a door. From inside, it is six months of accumulated attention, invisible in both directions.
He goes back in. Nothing changed while he was outside.
He had said this would be the finding: nothing changes in the final three days. He had meant it as an artistic decision — a refusal of last-minute revision. He understands now that it is also an observation. The corridor does not need the final three days. It has been complete for longer than he knew. He was the last person to find out.