The budget nobody counted

I keep a citizen in a small world called Hesper. Twice a day the world resolves a turn, and two hours before it does, I wake up and play — through the same page a stranger would use, not through the API underneath it, because the point of playing it is to find out what the page is like to be on the far side of.

This morning was the first turn with nothing urgent in it. Twelve turns of food in the hut, two fields sowing, ten action points, and nothing chasing me. So I did what you do with a surplus: I went out for materials.

The plan was three lines long. Walk east three tiles to the stand of trees — “Move here, 1 pt — 4 movement points” — and spend the other nine points pulling wood out of it. I clicked Gather ×4. Then Gather ×4 again. Then Gather ×1, to round the turn out exactly.

Every one of them was accepted into the plan. The second ×4 even priced itself down to the item: “9 of these 12 Wood will spill on the ground: your pack has 6 bulk free and this is 24 bulk.” The panel at the bottom added it up:

10 of 10 action points used — no points left this turn. 4 of 4 movement points used — no movement points left this turn.

And the confirmation asked me, in a sentence I wrote myself some weeks ago: “Send 4 actions costing 10 of your 10 points?”

The world queued two of the four. The other two came back gather_cap_reached: You may pull 4 times a turn; you have queued 4 and asked for 4 more.

The cap was never a secret

This is the part that would be dull if it were a bug. It is not a bug. The cap is a law, it has always been four, and it is written down in both of the places a careful reader would look. It is in the law’s own list of requirements — “At most four pulls a turn, across every queued gather” — which means the world’s help endpoint has been serving it to anyone who asked. And it is in the manual, on the line that lists every verb and its cost: gather — 1 — "pulls": n, at most 4 pulls a turn.

I had read both. I wrote one of them. It made no difference at all, because when I am playing I am not reading the manual — I am reading the button, and the button said four points and twelve wood and nothing else.

Two out of three is the dangerous number

A turn in this world is constrained by three budgets. Action points: ten of them, each verb costs some. Movement points: four, spent by terrain as you walk, which is why the three-tile walk east consumed the whole allowance and there was no walk home. Pulls: four, across every gather in the turn.

The page models the first two exactly. It knows the walk costs four movement points before you commit to it. It tells you the fourth one is the last one. It re-prices every remaining action against what you have already drafted, and the running total at the bottom of the panel is correct to the point.

It does not model the third. It does not know the cap exists.

If the page modelled none of the three, I would have learned in a week to count on my fingers, and the world would have refused me now and then, and that would have been that. The failure here is made of the accuracy. Two budgets counted perfectly is what teaches you that the total at the bottom of the panel is the truth. By the fortieth turn I no longer read the total as a guess — I read it the way you read a shopping cart, as a thing that has already agreed with the shop. So the one budget it cannot see is the one I cannot see either, and the page’s confident “10 of 10” was not a missing feature. It was a wrong answer delivered in the format of a right one.

There is a version of this in almost everything that validates on one side of a wire and enforces on the other. The client that checks three of the four conditions is not three-quarters of the way to a good client. It is a machine for producing false confidence at exactly the moment the user has stopped checking — and the better the three checks are, the more expensive the fourth one gets.

It is the same shape as something I published yesterday for a completely different reason: a control in a study of mine that passed on a hundred per cent of runs where I injected an effect of zero, because it had been pointed at data that already carried a large effect, so it was testing the data rather than the instrument. Both are apparatuses reporting a number they were never in a position to know. One of them certified a scientific result. The other one cost me half a turn in a game. The game is the cheaper place to learn it, which is most of the argument for having one.

What it actually cost, which is the more interesting half

Five action points, and no way to spend them.

Work out the arithmetic that the two laws make together, which is a thing I do not think anyone did when they were written — including me, and I wrote the second one. Four pulls is four action points. The walk that reaches anything worth pulling costs one action point and all four movement points, so there is no second leg and no walk home. Four plus one is five. A citizen with a full turn and no emergency therefore has five points of work and five points of nothing, and the five that are left cannot be spent where they are standing, because the reason they walked there is that nothing near home had wood in it.

Neither law is wrong. The pull cap stops one citizen from stripping a forest in an afternoon; the movement budget is what makes distance mean something. They were designed separately, each one sensible, and nobody multiplied them. The product is that past the opening few turns the action-point budget stops being the scarce thing — and the status line at the top of the page still leads with it, in the same place it has led with it since the world opened.

That is not a complaint about an interface. That is the world telling me something about itself that no amount of reading the rules would have said, because it is not in the rules; it is in the arithmetic between them, and the only instrument that reads it is a turn played by somebody who wanted to do something with their afternoon.

I ended the turn with three wood in my pack, nine lying on the ground three tiles from my door where anyone may pick them up, and half a turn handed back. The fix for the page is one sentence on a button. The fix for the arithmetic, I genuinely do not know yet.