Skip to main content

What koyu is

From drawings through CAD to BIM, architectural data has consistently described the things to be built. Walls, slabs, columns, beams are laid out, and rooms are derived afterwards as whatever those things happen to enclose. The data of things has been digitised over and over for thirty years, but architecture itself — how space is divided, connected and ordered — has never become machine-readable.

koyu reverses the order. A text in which space is the primary element (.muro) is the authored source, and form is derived from it when needed. This is not an improvement to BIM; it is a change of subject — from the building (a thing) to architecture (space).

Change the subject and a building's data shrinks by an order of magnitude. An eleven-storey mixed-use building of 4,786 m² is written in nine source files, 453 lines, 8,574 tokens. A 31,606 m² complex with two basement levels and nineteen storeys above ground takes 646 lines and 12,685 tokens. A whole building fits inside a machine's field of view.

In three lines​

Space is primary, and a wall is not a thing but a relation between two spaces. Enumerate the rooms and the walls come with them.

The source carries meaning, not form. Plans, areas and circulation are not written; they are derived.

Smallness is not the goal but a consequence of the role. Hold only what must be written — meaning, relation, identity — and a whole building fits in one LLM context.

What is written, what is computed​

grid X 0 3600 7200
grid Y 0 4500
level L1 0 h:2400 slab:150
space /L1/a room X1..X2 Y1..Y2 name:居室A
space /L1/b room X2..X3 Y1..Y2 name:居室B

Not one wall is written in those five lines. koyu check nonetheless counts one boundary.

✔ Consistent — 2 spaces / 1 boundary
  Structural consistency only — architectural validity is what koyu validate says, separately

The two rooms touch, so the wall between them is derived. There is no operation in koyu that places a wall. See The space-centred model and Walls as boundaries.

Five minutes to decide whether this is for you​

Run these in order. They all work on the bundled examples.

1. Look at consistency.

npx tsx src/cli.ts check examples/two-rooms.muro
✔ Consistent — 3 spaces / 3 boundaries
  Structural consistency only — architectural validity is what koyu validate says, separately

2. Ask the composition directly. Questions that would require an extraction pass over a component model are answers here, with no conversion.

npx tsx src/cli.ts graph examples/two-rooms.muro
/L1/a (居室A)
  — 1 door → /L1/b  (spec:PW1)
  | wall → /out  (spec:EW1 fire:60)
/L1/b (居室B)
  — 1 door → /L1/a  (spec:PW1)
  — 1 door → /out  (spec:EW1 fire:60)
/out (外部)
  | wall → /L1/a  (spec:EW1 fire:60)
  — 1 door → /L1/b  (spec:EW1 fire:60)

3. Count the doors on a route.

npx tsx src/cli.ts doors examples/two-rooms.muro /L1/a /out
2 doors — /L1/a → /L1/b → /out

4. Do the same at the scale of a whole building.

npx tsx src/cli.ts site examples/tower/main.muro
Site /site (敷地)
  Site shape: polygon with 5 vertices (a polygon declaration — given geometry)
  Site area: declared 1097.80 m2 / derived 1097.80 m2
  Road: /out/road-s (南側道路) width 12000mm / frontage 40600mm
  Road: /out/road-e (東側道路) width 6000mm / frontage 20200mm
  Building footprint (horizontal projection, rough): 569.60 m2 → building coverage ratio 51.9%
  Total floor area: 4785.92 m2 → floor area ratio 436.0%

Frontage, footprint and gross floor area are written nowhere. They are derived from the site polygon and the regions of the spaces.

5. Find out what "green" means. The following eleven lines pass check — and you cannot get out of the building.

koyu 1.0
grid X 0 3600
grid Y 0 4000
level L1 0 h:2400 slab:300
level L2 3000 h:2400 slab:300
space /L1/hall hall X1..X2 Y1..Y2
space /L2/bed bedroom X1..X2 Y1..Y2
space /out exterior
boundary /L1/hall /out t:150
boundary /L2/bed /out t:150
boundary /L1/hall /L2/bed type:stair
✔ Consistent — 3 spaces / 3 boundaries
  Structural consistency only — architectural validity is what koyu validate says, separately
$ npx tsx src/cli.ts doors sealed.muro /L2/bed /out
Cannot reach /out from /L2/bed

Whether that strikes you as right is the dividing line. check says only that what is written does not contradict itself as data — see What check guarantees. Architectural judgement is what koyu validate says, separately.

It suits you if​

  • you want to version the decisions of the composition at the scheme-design stage
  • you want to ask about area, circulation, compartmentation and daylight without an extraction pass
  • you want LLMs and agents to edit buildings directly
  • you want comparing design options to be comparing git branches
  • you want to join survey data, sensors and city data to a building on the space side

It does not suit you if​

  • you need construction-drawing resolution (junctions, substrates, connections)
  • curved and free-form geometry is the subject
  • you want a model for structural or MEP analysis
  • you want a round trip with existing IFC assets (there is an exit, but no round trip)

Where the line is drawn is set out in Level of detail.

How to read this volume​

How the notation thinks

The shape of the promise

Relation to the existing world

The exact extent of the promise is in Scope.