The best bit
When Cog finishes something they do not walk away. Cog goes back over it, counts it, measures it, and reads you the numbers they found. So you never discover on Saturday that the bridge you crossed on Tuesday had a gap in the middle of it.
Watch the front come away. Saying a house is walk-in is easy; Cog went and stood in it, 14 blocks past the wall.
What checking means
A build can look perfect from one angle and still be wrong. So Cog reads the actual blocks and entities back out of the world and checks the things a picture cannot show you: whether the road is one unbroken shape, whether every gondola sits the same distance from the hub, whether the lamps really go dark when the power does. Cog runs the same checks over the plan before the first block lands, so most trouble never gets built in the first place.
The proof
Cog walks the finished road end to end. One connected piece, no notches missing out of it, no step too tall to walk up, and the fence stays on the road it belongs to. A bridge gets the same treatment before they tell you it holds.
357 columns · 1 piece · 0 holes · 0 unwalkable steps · 0 stray fence
Every rim segment, spoke and gondola gets counted against the plan. Then they measure each gondola out from the hub themselves, rather than trusting the drawing. A wheel with a gondola sitting a block proud of the others is not a wheel.
92/92 parts · every gondola at radius 12.000 · rim gaps under 1 block
A design names the block for every cell before a single one is placed, so this is the one they can check completely rather than sample. Cog reads back every block of it.
SpongeBob house 24,688 of 24,688 · pirate galleon 30,263 of 30,263 · rocket 22,035 of 22,035 · treehouse 35,252 of 35,252 · stone dragon 36,530 of 36,530 · 0 wrong between them
This one cannot be worked out on paper, and we tried. Measure the air with walls around it and the space between a stone dragon's legs counts as a room. Flood the space in from outside instead and a house with a front door comes back as solid, because the flood walks in through the door. So they stop calculating and go and do it: they stand outside, picks the spot furthest in from the walls with the most of the building over their head, and walks to it on foot, with the same physics as anybody else. Either they are standing in there at the end or they are not — and when they cannot find a way in, that is what they say, rather than telling you it is walk-in.
6 of 8 designs walked into · furthest in 32 blocks, under 13 blocks of building · 2 they could not find a route into
A datapack with a typo in it installs perfectly, enables perfectly, reports success and then does nothing at all, forever, silently — so "the rules are live" is not worth saying on its own. Every rule counts its own firings, and then each one is set off deliberately: a snowball dropped into the goal mouth, a score driven to its winning value, the clock wound to the tick a timer waits for. For the rules that need a person standing somewhere, Cog goes and stands there — they are a player, so nothing has to be taken on trust.
Six games, 67 rules · every one triggered on purpose · 67 of 67 fired · 0 untested
Cog flips the lever on and watch the wall slide across. Cog flips it off and watches the doorway come back. Then they do it again, at 2 blocks wide, at 4, and at 6, because a secret door that only works once is just a hole.
opens and seals at 2, 4 and 6 blocks wide · every time
Redstone
Redstone is where clever machines usually fall over — one block out of place and the whole circuit is dead. On an independent redstone benchmark, every frontier model tested plateaus near a quarter correct. So Cog does not improvise the wiring. Cog places circuits from a library that has already been built and checked, which is why the hidden door slides open the first time you flip the lever, and the hundredth. Read the six wire rules that library is built on.
The scoreboard
Gather, tools, craft, drop, pickup, chest put, chest take, farm, combat. Each one run three times in the same arena, the world reset in between so nothing can drift the result. 26 of the 27 runs landed, and that is the number on the page. A full errand — gather, walk, deposit, with nobody watching — landed 8 times out of 8. Numbers are worth something precisely because we print the one that missed.
Read next
We are opening a small number to begin with. Put your name down and we will tell you when yours is ready.