You are the last classifier.
File the slips. Write the rules the hall keeps repeating. The rules are what move the readers.
No standing rules. The library is writing its own.
The hall is running itself.
It just does not know it yet.
Eleven readers. Four bays. A counter of record slips. Every slip you file feeds a bay, and every reader you starve walks out. When the same two classes of finding keep turning up in the same bay, the hall notices a pattern — and you can write it down as a Standing Rule.
A rule pools two classes into one bay. If that empties a bay, the bay is shut, and everyone standing in it is lost for good. You can withdraw a rule to reopen the path. You cannot get the readers back.
The index is empty.
Held.
The readers wait where they stand. They will wait a while.
The hall keeps running.
How the index works
File. A slip on the counter carries one of four classes — Minute, Binder, Provenance, Condensation. Drag it to a bay mouth. A bay only answers readers whose class is keyed to it, so a slip in the wrong bay is a page nobody will ask for. Each bay holds five pages; overfill and the oldest is reshelved away.
Promote. When two classes of reader keep ending up at the same bay, a pattern chip appears with three marks. Writing it down makes a Standing Rule: the first class is filed with the second, from then on. If that leaves a bay with nothing keyed to it, the bay shuts.
Shut bays cost readers. Everyone inside a bay at the moment it shuts is refused, and refused readers never come back. Count who is standing at a bay before you promote.
Withdraw. A Standing Rule can be withdrawn. The bay reopens and the paths free, but the ledger keeps every refusal the rule ever caused — the hall is permanently smaller.
Read the hall. Thin threads show where each reader is headed. Faint lines appear between readers who keep passing each other; when a line joins two readers of the same class, the hall has sorted itself. When circulation is low the chip reads QUIET.