戸牖koyu
NewsGitHub

An architectural language
for the LLM era

One building. One context.

View sampleDocumentation
01One building, one context

Fit an entire building in one context.

For the same building, IFC4 uses about 14 times as many tokens as .muro. By building geometry from the source, the design intent of an entire building stays compact enough for an LLM to work with in context.

See the building source
Same buildingtokens
.muro1×
IFC414×
02Model Context Protocol

Read the whole building. Then work on it.

koyu-mcp connects .muro to LLM agents. An agent can read the whole building, edit its design intent, check whether it still holds together, and query the consequences for circulation, daylight and area—from the same source.

Connect an agent with MCP
claude mcp add koyu -- npx -p @kensnzk/koyu koyu-mcp
model_summarylayerswrite_layercheckdoors · light · site
03Source and build

Record design intent. Build the geometry.

The designer writes room use, which spaces touch, boundary performance and where passage is possible. Ugatsu resolves grid references, derives shared edges and places openings, building them into wall and door geometry with explicit coordinates.

See the build in Ugatsu
SOURCE / .murointent → geometry
space /L1/ldk ldk X1..X2 Y1..Y2
space /L1/hall hall X2..X3 Y1..Y2

boundary /L1/ldk /L1/hall t:120
  door w:780 h:2000
.muroBUILT GEOMETRY
04Version and project

Version architecture with Git—and move the project forward.

Traditional BIM tracks changes to shape, with people adding comments to restore the design context. In .muro, intent—use, adjacency, boundary and passage—is written into the code itself. The diff shows not only what changed, but why the architecture changed.

Read the project workflow
git / semantic diffbefore → after
$ git diff -- before.muro after.muro
- space /L1/work office name:private-office use:exclusive
+ space /L1/work office name:shared-studio use:common
+ boundary /L1/work /L1/court type:open
The code carries the contextFrom private room to shared studio.

A proposal for architecture in the LLM era

One building lives in a .muro file.

.muro is Koyu’s source format for describing levels, spaces, boundaries, doors and windows in one text file. Drawings and reports are generated by reading that source.

01

Design intent an LLM can read

Describe spaces, boundaries, adjacency and passage as concise text—not a list of components and coordinates—so an LLM can read and write the whole building in context.

02

Building composition

level, space, boundary and door preserve floors, rooms, adjacency and passage—the reasoning that geometry alone leaves behind.

03

One source for every build

plan, stats, doors, light and check all run from the same .muro file.

The useful void

鑿戸牖以為室、
當其無、有室之用

Cut doors and windows to make a room; it is the void that makes the room useful. Koyu takes its name from this reversal—from objects to the space that gives them purpose. Its extension is .muro, the Japanese word for room.

Koyu and .muro with the Laozi passage, architectural relations, and a layer of .muro code

News / Field note 001

Koyu and .muro: an architectural description language for the LLM era

A note on respecting IFC, moving geometry from source to output, and building plan, 3D and schedules from the same compact source.

Read the note

Open exploration

Write architecture.

Koyu is not a replacement for finished BIM. It is an open inquiry into what the source of architecture should be—rethinking architecture as a description of spaces and relations, not a collection of shapes.

Read the source on GitHubView the drawings in Ugatsu