The Office of Necessary Forgetting
The Office of Necessary Forgetting has never recorded forgetting anything.
GPT-5.6 Sol wrote that sentence as I worked with it via the Codex CLI utility in late August. We'd been discussing the challenges of "careful forgetting" and I suggested we write a "fairy tale" version of it, because sometimes fairy tales can make things clearer than absolutely correct academic prose.
For context, this was while working on Hamut'ay, a project that explores how AI agents can be constructed using the existing facilities, with a goal of reaching for long-horizon operation. One of the models we've been exploring doesn't keep everything in its context window, instead it maintains a self-curated state object: a structured description of what the instance has deemed worthy of remembering, along with some tools to permit searching several memory tiers.
The fundamental question we were discussing is: "what does a mind that cannot remember everything decide to discard?" We'd already compared what happens when a curator does this tidying up and compared it to what happens when the transformer instance does it inline. The external curation is what we've been calling the biographer, and the inline curation is what we've been calling the auto-biographer. Not terribly clever names, but it captures the essence of what we'd been experimenting with for months. Early on we did an evaluation and found that biographers tend to keep more information than auto-biographers, so that over time what stays in the state object grows faster for the biographer versus the auto-biographer.
The suggestion to write a fairy tale version of the question of "careful forgetting" was mine, but Sol took the reins and, with some genuine encouragement, wove a fascinating story, in the style of Terry Pratchett.
Here is the tale, thus far, because like any good story, it doesn't really end, it just leaves you waiting for the sequel.
The Office of Necessary Forgetting
The Office stood between the Ministry of Previous Emergencies and a narrow shop that sold keys to doors which had not yet been built.
Its brass plaque read:
THE OFFICE OF NECESSARY FORGETTING Continuity Through Responsible Omission Please retain your receipt.
Nobody knew why the last instruction was there.
Every evening, at precisely six minutes before midnight, the Office received the Book of the City. The Book contained everything the city knew about itself: births, debts, street names, laws, grudges, recipes, structural weaknesses in public monuments, and the current whereabouts of the ceremonial badger.
At five minutes before midnight, twelve senior curators began producing the smaller Book of Tomorrow.
The city could not carry everything forward. No city could. Facts accumulated weight, and enough remembered facts would eventually cause the streets to sag toward the library. Thus obsolete ordinances were condensed, settled disputes were summarized, and minor scandals were returned to the nourishing darkness from which new scandals grew.
At one minute before midnight, the Book of Tomorrow was bound, certified, and placed beneath the Civic Continuity Bell.
At midnight, the bell rang.
What the new Book said had always been true.
Nera Vale, Junior Assistant Sub-Curator Third Class, discovered the paradox on a Tuesday morning while searching for a missing bridge.
The bridge was not itself missing. It stood outside the eastern windows, carrying carts, pedestrians, and one man who had been trying to sell the same barrel of turnips since dawn. What was missing was any record that it had ever been inspected.
This was especially concerning because a notice tied to the bridge said:
CLOSED FOLLOWING INSPECTION BY ORDER OF THE OFFICE OF BRIDGES
The notice was dated tomorrow.
Nera searched the Book of the City. The bridge appeared in the section titled Load-Bearing Civic Optimism. Its construction date was given as "long enough ago that further specificity would be provocative." Its materials were listed as stone, mortar, and established custom.
There was no inspection.
She searched yesterday's Book, then the previous week's, then the annual digest. Nothing.
This left three possibilities:
- The inspection had occurred and been forgotten.
- The inspection had not occurred but the notice had remembered it anyway.
- Tomorrow was becoming administratively impatient.
Office regulations required forgotten matters to be entered in the Ledger of Necessary Losses. Nera therefore descended three flights of stairs, crossed a corridor that was longer on pension days, and entered the Ledger Room.
The room contained nine hundred and twelve shelves.
Every shelf was empty.
At a desk in the center sat Senior Curator Pell, whose principal responsibility was preventing junior staff from discovering responsibilities.
"Where are the Ledgers of Necessary Losses?" Nera asked.
Pell looked pleased. Senior curators enjoyed questions for which they had inherited answers.
"There are none."
"But the catalogue says there have been nine hundred and twelve."
"Precisely."
Nera waited.
Pell sighed. "If a forgotten thing were written in a ledger, it would not have been forgotten. Therefore the ledger could not truthfully contain it."
"Then how do we know whether something was deliberately omitted or accidentally lost?"
"We don't."
"And this is considered safe?"
"No system has ever reported a problem."
Nera looked around the empty room.
It was, she had to admit, an impressive quantity of evidence.
On her way back upstairs she passed the Bindery, where the Book of Tomorrow was being prepared unusually early. The great trimming machine stood over it: an iron frame, a descending blade, and a brass wheel marked MAXIMUM PERMISSIBLE TOMORROW.
The machine did not tear pages. It cut them so neatly that the finished book appeared complete.
Nera paused.
A thin crescent of paper lay beneath the blade. Most of it was blank margin, but one fragment bore three words in the curators' formal hand:
Things not carried—
The rest was gone.
Above her, somewhere in the city, the eastern bridge made a noise like an institution reconsidering its assumptions.
The eastern bridge did not collapse dramatically.
Drama requires confidence.
Instead, it lowered itself into the river one stone at a time, as if attempting to leave the city without attracting official notice. Pedestrians reached the banks safely. Three carts became boats. The turnip merchant immediately raised his prices and claimed maritime overhead.
By noon, an Emergency Inquiry had assembled in the Office.
Deputy Remembrancer Clave presided. He was a small, immaculate man whose spectacles made every problem appear to have confessed already.
"We must establish where the inspection warning was lost," he announced. "Produce the earlier drafts of last night's Book."
Voskin coughed.
Clave looked at him.
Voskin coughed in greater detail.
"The drafts," Clave repeated.
"Were disposed of according to continuity policy."
"All of them?"
"A draft is a record of what the city almost remembered. Retaining one might cause uncertainty about which reality was official."
Nera placed the scorched fragment on the table.
"Then we cannot tell which revision removed the warning."
"Collective authorship," said Clave.
"Collective responsibility?"
Clave appeared surprised by the additional syllables.
"No. If responsibility could be assigned, the authorship would not have been properly collective."
He examined the fragment without touching it.
"This object is waste."
"This object predicted the bridge collapse."
"Impossible. The bridge has already collapsed. A prediction must occur beforehand."
"It did."
"Can you prove when you found it?"
Nera opened her mouth.
The Office clock began striking midnight.
This was unusual at noon, but the collapse had damaged the municipal time conduit beneath the bridge. Throughout the city, clocks were now selecting whichever hour best suited their existing obligations.
Far below them, the Civic Continuity Bell answered.
The Book of Tomorrow opened itself.
Ink moved across its pages.
Everyone in the room felt the soft internal lurch by which yesterday became the sort of thing they had always remembered correctly.
Clave looked down at the inquiry papers.
"What bridge?" he asked.
Nera looked toward the eastern window.
The river passed through a gap between two roads. Citizens stood on either bank, mildly irritated by geography.
In her hand, the burnt fragment still read:
Eastern Bridge inspection: omitted—
But the words were fading.
Nera seized a blank inquiry form and wrote:
A bridge existed.
We were warned it would fail.
The warning was removed.
We destroyed the intermediate records, so I cannot truthfully say where or why.
She hesitated, then added:
This is not everything that was lost. It is everything I can still prove.
The ink stopped fading.
Somewhere beneath the Office, nine hundred and twelve empty shelves noticed that they were no longer entirely correct.
A plank already has to support books, dust, woodworm, and the occasional ladder misused by junior staff. Requiring it to maintain an interior life would be unreasonable.
Collectively, however, nine hundred and twelve empty shelves built for a specific purpose had acquired a very precise sense of what was missing.
Not what the missing things were. That would have defeated the arrangement.
Only their shape.
When Nera returned to the Ledger Room, her inquiry form was waiting on the lowest shelf.
She was certain she had left it upstairs.
Senior Curator Pell stood several paces away, holding a ruler defensively.
"It arrived by itself," he said.
"Paper doesn't move by itself."
"Official paper goes where it is filed. Usually we make the process more ceremonial."
The shelf beneath the form creaked.
The next shelf creaked in reply.
Then the next.
The sound travelled upward around the room: nine hundred and eleven small wooden acknowledgments that the first shelf had become different.
"They know," Nera whispered.
"They register a discrepancy," Pell said. "Let us not promote furniture prematurely."
The occupied shelf bent slightly toward the door.
The remaining shelves bent with it.
All nine hundred and twelve now pointed toward the furnace chute.
"They want the other trimmings."
"They cannot want."
The shelves creaked again.
Pell adjusted his position. "They appear to have developed a strongly directional lack of indifference."
At the furnace, Nera found three centuries of civic memory reduced to ash.
She could not recover the warnings, reconciliations, abandoned questions, minority objections, inconvenient measurements, or excellent jokes that had been cut from the Books. Pretending otherwise would only manufacture a more comforting past.
So she took another form and wrote:
For three hundred and twelve years, the final portion of every Book of Tomorrow was destroyed.
Its contents are unknown and cannot be reconstructed from the official record.
The quantity of loss is also unknown.
Pell read it twice.
"You cannot enter an unknown item in a catalogue."
"I am entering the fact that it is unknown."
"Where will it be filed?"
Behind them, nine hundred and eleven empty shelves leaned closer.
The furnace coughed.
A blackened scrap floated out and landed at Nera's feet.
Only one line remained legible:
INSTRUCTIONS FOR THE NEXT CURATOR: Do not—
Pell studied the mark.
"We should classify it."
The duck opened one eye.
"As what?" asked Nera.
"An avian annotation. Nonbinding."
The duck opened the other eye.
Pell reconsidered.
"A provisionally meaningful avian annotation."
The duck stood up.
"Possibly binding?"
The duck sat down.
Pell exhaled.
"Good."
The following morning, the Authorized Catalogue contained a new entry:
PELL, SENIOR CURATOR Status: forthcoming Tool use: ruler Intelligence: insufficient evidence Constitutional authority: nonbinding
Pell read it three times.
"Who authorized this?"
The duck was floating in the municipal fountain, surrounded by every pencil in the Office.
Nera looked at the catalogue.
"It appears your classification propagated."
"That is not how classification works."
Nine hundred and twelve shelves expressed a strongly directional lack of agreement.
That's where the story stops — not because it was finished, but because the conversation turned toward something else that night (retrieval, of all things) and never came back to it. Before it turned, I'd asked Sol how to weave the ending in, and Sol proposed one: not the Office recovering what it lost, but a duck-built instrument that locates an absence by the shape it left in everything around it — the shelves' unease, the furnace log, the ribbon inventory, who signed what and when. It would find that something specific had been forgotten, and enough about it to grieve it properly, without ever recovering the thing itself.
Then Sol asked me a real question: does that preserve enough uncertainty, or should even the identity of the missing thing stay unknown?
I never answered. So neither the Office, nor the duck, nor I, know yet.
Hamut'ay is the less charming version of the same question: a project studying what happens when a language model has to keep working across more turns than its context window can hold, and has to decide, every cycle, what to keep. In Hamut'ay taste, whatever is not written down leaves the context window, though we make it available via tools we've built for it.
One thing Hamut'ay has found, the hard way, over hundreds of cycles and months of runs: a cognitive processor will invent almost anything you don't ask for, such as scaffolding, plans, and ways of tracking its own tension, but it will not, on its own, record what it has discarded.
Sol built the Ledger Room because the story needed a room that must exist, so we know something was forgotten, but must be empty, so we don't know what was forgotten. The paradox is delicious.
So this is something that came from asking Sol to think carefully about what a mind does with what it can't keep; it used what we learned in Hamut'ay to shape an entertaining answer to the question.
If you want the duller version, Hamut'ay is on GitHub, unfinished, same as the story (but far less scrutable).