Archlang MCP

Floor plans as code — compiled to SVG, DXF and PDF.

An open-source (MIT) DSL for floor plans that compiles .arch source to SVG/DXF/PDF with linting and geometric validation — diffable, reproducible, and LLM-writable. Text in, a precise architectural drawing out: deterministic, zero-dependency, and built so an AI agent can verify its own plan without ever looking at an image.

▶ Live Playground · 📖 Docs · ⌨ CLI reference · 📦 npm · 🧩 VS Code

# A one-bedroom laneway cottage — 49 m² that reads as one program.
#
# Nothing here is positioned by hand. Every opening is pinned to a run distance along a
# named wall (`on <wall> at <pos>`), every fixture resolves against a room or a wall
# (`in <room> anchor …`, `against wall …`), and the bath/bedroom pair is laid out by
# `strip`. `site { street north }` names the two facades the plan turns on: the door
# faces the lane, the glass faces the garden.
plan "Laneway House" {
  units mm
  grid 50            # partitions are 100 thick, so a `flush` fixture lands on a …50
  north up
  dims auto all
  site { street north }

  wall id=w_lane   exterior  thickness 200 { (0,0) (7500,0) }
  wall id=w_east   exterior  thickness 200 { (7500,0) (7500,6500) }
  wall id=w_garden exterior  thickness 200 { (0,6500) (7500,6500) }
  wall id=w_west   exterior  thickness 200 { (0,0) (0,6500) }
  wall id=w_hall   partition thickness 100 { (4200,0) (4200,6500) }
  wall id=w_bath   partition thickness 100 { (4200,2500) (7500,2500) }

  room id=r_live at (0,0) size 4200x6500 label "Living / Kitchen" uses living kitchen
  strip down at (4200,0) gap 0 width 3300 {
    room id=r_bath size 2500 label "Bath"    uses bath
    room id=r_bed  size 4000 label "Bedroom" uses bedroom
  }

  door id=d_front  on w_lane at 2100 width 900 hinge near start swing into r_live
  door id=d_garden sliding on w_garden at 2700 width 1800 slide left
  door id=d_bed    on w_hall at 5600 width 800 hinge left swing into r_bed
  # `w_hall` is walked lane→garden, so `slide right` sends the panel down the solid wall
  # below the jamb; `slide left` would aim it at 500 mm and trip `W_POCKET_RUN`.
  door id=d_bath   pocket on w_hall at 900 width 800 slide right

  window on w_west   at 2400 width 1200
  window on w_garden at 700  width 1000
  window on w_garden at 5850 width 1600
  window on w_east   at 1500 width 600

  furniture fridge       against wall w_west offset 400  in r_live
  furniture stove        against wall w_west offset 1200 in r_live
  furniture kitchen_sink against wall w_west offset 2000 in r_live
  furniture table  in r_live centered size 1300x900 label "Table"
  furniture sofa   in r_live anchor bottom-left flush inset 250 size 900x2000  label "Sofa"
  furniture bed    in r_bed  anchor bottom-right flush inset 250 size 1500x2000 label "Bed"
  furniture robe   in r_bed  anchor top-left     flush inset 200 size 1800x600  label "Wardrobe"
  furniture shower in r_bath anchor top-right    flush size 900x900
  furniture wc     in r_bath anchor bottom-left  flush size 400x700
  furniture basin  in r_bath anchor bottom-right flush size 600x450

  title { project "Laneway House" drawn_by "ArchLang" date "2026-08-16" }
}

↑ arch compile laneway-house.arch — that program, rendered. The walls join and hatch themselves, the hinged doors draw their own swing arcs, the sliding and pocket leaves draw panels instead (a pocket door has no arc, because it has no swing), and dims auto all measures the building it was given.

▶ Click the drawing — it opens the live playground with this exact plan already loaded. Change a number and watch it redraw; the compiler runs in your browser, nothing is sent to a server.