Important

🤖 Read this with your AI agent — don't read it by hand.

This repo is written agent-first. Point Claude Code, GitHub Copilot, Cursor, or any agent at it: "Read the README and AGENTS.md, then help me run / extend this." Structure + AGENTS.md are optimized for agent comprehension.

Floor plans as code — like Typst/LaTeX, but for architecture.

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

👀 See it

Here is a whole program, and below it the actual drawing it compiles to — not a mock-up. Walls join and hatch themselves, the door draws its own swing arc, the window draws its glazing, and the furniture is placed by anchor, never by hand-computed coordinates.

plan "Attached 1BR" {
  units mm
  grid 100
  north up

  strip right at (0,0) gap 0 height 4000 {          # a row of rooms, laid end to end
    room id=r_living size 4000 label "Living"  uses living
    room id=r_bed    size 3000 label "Bedroom" uses bedroom
  }

  wall id=w_north exterior  thickness 200 { (0,0) (7000,0) }
  wall id=w_south exterior  thickness 200 { (0,4000) (7000,4000) }
  wall id=w_west  exterior  thickness 200 { (0,0) (0,4000) }
  wall id=w_east  exterior  thickness 200 { (7000,0) (7000,4000) }
  wall id=w_part  partition thickness 100 { (4000,0) (4000,4000) }

  door id=d_main on w_south at 2000 width 1000 hinge near start swing into r_living
  door id=d_bed  on w_part  at 2000 width 900  swing into r_bed   # opens INTO the bedroom

  window on w_west at 50% width 1400                # centred on the wall, by construction
  window on w_east at 50% width 1200

  furniture sofa in r_living anchor top-left inset 300 size 2000x900  label "Sofa"
  furniture bed  in r_bed    anchor right    inset 300 size 1500x2000 label "Bed"
}

↑ arch compile attached.arch — that program, rendered. Nothing above places a wall corner, a door leaf or a sofa by hand.

▶ 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.

Why a link and not a live embed? ArchLang does ship an embeddable viewer — but GitHub's markdown sanitizer strips <iframe> (it comes back as escaped text, exactly like <script>), so no README on GitHub can host one. The embed works everywhere GitHub isn't: see Embed a plan anywhere. Source: examples/attached.arch.

🌟 Introduction

ArchLang is a small declarative language for floor plans. You declare a plan — walls, rooms, doors, windows, furniture — and the compiler renders a clean, professional SVG (also DXF, PDF, PNG, and a zero-dependency ASCII plan).

Coordinates are integer millimetres, so output is deterministic: the same source always produces byte-identical bytes, and changing one number changes exactly one thing. "Make the bedroom 1 m wider" is a one-number diff — not a re-roll of a raster image that silently redraws the kitchen too.

The compiler is pure TypeScript with zero runtime dependencies and is isomorphic — the same code runs in Node and in the browser, which is why the playground is fully client-side.

ArchLang is the floor-plan engine behind ArchCanvas, an AI design agent — but it stands alone and is useful in any app or script.

💡 Why it is different

Most "AI floor plan" tools generate a picture. A picture cannot be checked, diffed, or reasoned about — and neither the model nor you can tell whether the bathroom is actually reachable.

ArchLang generates a program, and then lets you interrogate it as facts:

	Raster image generation	ArchLang
Output	pixels	a .arch program → SVG / DXF / PDF / PNG / TXT
Edit "widen the bedroom"	re-roll the whole image	change one number
Same input twice	different image	byte-identical output
"Is the bath reachable?"	look at it and guess	arch describe --json → access graph
"Does it match the brief?"	eyeball it	arch validate --intent → exit code
Wrong syntax	—	errors returned as data, each carrying its own fix

That last row is the whole design: compile() never throws. It returns diagnostics with byte spans and a machine-applicable fix, which is what makes a tight self-correction loop possible.

🤖 The agent loop

An agent can author a plan, correct itself, and confirm the plan matches the brief without rendering an image at all — which is what makes ArchLang cheap to drive from a text-only model.

flowchart TD
    B([Brief]) --> S["<b>arch context</b> — the whole language, one call"]
    S --> W["Write <b>.arch</b>"]
    W --> C{"<b>arch compile --json</b>"}
    C -->|"ok: false"| F["<b>arch fix</b><br/><i>each diagnostic carries its own fix</i>"]
    F --> C
    C -->|"ok: true"| D["<b>arch describe --json</b><br/><i>rooms · areas · adjacency · access graph</i>"]
    D --> V{"<b>arch validate --intent</b><br/><i>does it meet the brief?</i>"}
    V -->|"no"| G["<b>arch suggest</b><br/><i>candidate door / window statements</i>"]
    G --> W
    V -->|"yes"| O([SVG · DXF · PDF · PNG])

    style B fill:#ede7f6,stroke:#6b3ae0,color:#1a1a1a
    style O fill:#e8f5e9,stroke:#2e7d32,color:#1a1a1a
    style C fill:#fff8e1,stroke:#7a6000,color:#1a1a1a
    style V fill:#fff8e1,stroke:#7a6000,color:#1a1a1a
    style D fill:#e8f5e9,stroke:#2e7d32,color:#1a1a1a
    style F fill:#fdecea,stroke:#b3261e,color:#1a1a1a
    style G fill:#fdecea,stroke:#b3261e,color:#1a1a1a

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Cold start in one command. arch context prints the entire agent context — language spec, workflow skill, CLI reference and every diagnostic code — as one system-prompt-ready document (the same llms-full.txt the docs site serves).

npx @chanmeng666/archlang context                       # EVERYTHING: spec + skill + CLI + error catalog
npx @chanmeng666/archlang spec                          # just the language, one page (~2k tokens)
npx @chanmeng666/archlang compile plan.arch --json      # render → { ok, diagnostics, summary }
npx @chanmeng666/archlang fix plan.arch --dry-run       # preview the machine-applicable fixes
npx @chanmeng666/archlang describe plan.arch --json     # VERIFY, without an image
npx @chanmeng666/archlang validate plan.arch --strict   # the ship gate

Every command takes --json (result on stdout, messages on stderr) with deterministic exit codes (0 ok · 2 user-source error · 1 IO · 3 usage). Full list: CLI reference · arch manifest --json returns the same thing as data. See SKILL.md.

Machine-native artifacts — Plan JSON, a GBNF grammar, an intent schema, and an optional MCP server

Artifact	Use
/plan.schema.json	Emit structured JSON, compile it with arch compile --from-json
/archlang.gbnf	Constrain a local model to parseable output
/intent.schema.json	Write the brief down as a contract; gate on it with validate --intent
/llms-full.txt	The whole context bundle (arch context)

MCP server (optional). @chanmeng666/archlang-mcp is a stdio Model Context Protocol shim over the library, listed on the official registry as io.github.ChanMeng666/archlang-mcp:

claude mcp add archlang -- npx -y @chanmeng666/archlang-mcp

Prefer the CLI when your agent has a shell — a CLI costs nothing in the context window until it is called, whereas an MCP tool schema sits there permanently. The server exists so MCP-native hosts can discover ArchLang. The core stays zero-dependency; the SDK lives only in that package (ADR 0012).

In CI: .github/actions/arch-render renders every ```arch fence in your Markdown to images in one step.

✨ Features

It draws like an architect, not like a plotter

Poché-hatched walls (by material), door swing arcs, window glazing, computed room areas, dimension lines, layers, line weights, a north arrow, a scale bar and a title block. Real fixture symbols for WC, basin, shower, bathtub, sink, counter, fridge and stove — plus dims auto to synthesize dimension strings for you.

It checks architectural soundness, not just syntax

arch lint encodes tacit professional knowledge: a bathroom reachable only through a bedroom, a wet room that isn't fully walled in, a door whose swing hits furniture or another door, a windowless bedroom, an unenterable room, a too-narrow door, a bath/kitchen with no fixtures, and a room whose use was merely inferred from an indirect label (W_ALIAS_MATCH — with a fix that pins the explicit uses). All tunable via the ruleset.

It models how a person actually walks the plan

arch describe runs a clearance-eroded nav grid: per-room walk distance, the narrowest pinch on the way in, and how circuitous the route is — with advisory lint for a too-tight (W_PATH_TOO_NARROW) or roundabout (W_CIRCUITOUS_PATH) walk, and an opt-in arch compile --overlay circulation that draws the routes on top of the plan.

Facts and advice — never an invisible auto-arranger (ADR 0005). arch repair is the one explicit corrector: it pushes furniture out of walls, doorways and swing arcs, and emits a change log you review.

Errors are data, and many carry a machine-applicable fix

compile() never throws on bad source — it returns diagnostics with byte spans, a catalogued E_*/W_* code, and a fix. Where the edit is mechanical, the diagnostic also carries applicable fixes that arch fix applies for you. --error-svg even turns a plan that won't compile into a self-describing error card an agent can look at.

Parametric, scriptable, and still deterministic

Values, arithmetic, arrays, for/if/while and pure functions — plus relational placement (right-of / below / …) and room strips, resolved by deterministic topological arithmetic, not an optimizer. All of it expands at compile time: no runtime, no clock, no I/O. Optional metric unit suffixes (4m / 40cm / 20mm) fold exactly to millimetres at lex time.

Five output formats · accessible SVG · IDE-grade tooling

SVG, DXF and a TXT ASCII plan with zero dependencies; PDF (vector, selectable text) and PNG (deterministic raster) via optional, lazily-loaded add-ons the default install never pulls. arch compile --accessible stamps the SVG with <title>/<desc> + role="img".

A full LSP (hover, completion, go-to-definition, rename, signature help), an arch fmt formatter, an arch explain <CODE> catalog, and a VS Code extension.

🚀 Quick start

npx @chanmeng666/archlang new -o plan.arch          # scaffold a starter plan
npx @chanmeng666/archlang compile plan.arch -o plan.svg

Or install it:

npm install @chanmeng666/archlang

As a library (zero dependencies, runs in Node and the browser):

import { compile } from "@chanmeng666/archlang";

const { svg, diagnostics } = compile(`
plan "Tiny" {
  units mm
  grid 50
  wall exterior thickness 200 { (0,0) (4000,0) (4000,3000) (0,3000) close }
  room id=r at (0,0) size 4000x3000 label "Studio"
  door at (2000,3000) width 900 wall exterior hinge left swing in
  window at (0,1500) width 1200 wall exterior
}`);

// compile() never throws — errors come back as data, each with a span and a fix.
if (diagnostics.some((d) => d.severity === "error")) console.error(diagnostics);
else writeFileSync("tiny.svg", svg);

Also exported, all pure: describe() (facts), lint() (soundness), validateIntent() + projectSubscores() (does it match the brief?), repair(), applyFixes(), suggestTopology(), renderAscii(), toDxf(), and the LSP core (completion, hover, …).

Develop this repo

npm install          # one install bootstraps every workspace
npm run build        # build the library + CLI into dist/
npm run check        # typecheck + lint + the full test suite
npm run check:drift  # every generated artifact must match its source
npm run playground:dev   # build the core, then open the playground

🖼️ Gallery

Every one of these is a real, compiled example from examples/ — click through to the source.

studio The flagship: fitted kitchen & bath, enclosed bath off a central hall. Lint-clean.

two-bed A larger plan: central corridor, multiple rooms and openings.

attached No hand-computed coordinates: strips, on-wall openings, anchors.

Also in examples/: parametric (a for loop that generates units), themed (a custom theme + brick hatch), relational (right-of / below), and accessible (accTitle/accDescr). The docs gallery renders all of them live and editable in the browser.

🏗️ How it works

ArchLang is a compiler pipeline. Source text becomes a backend-neutral Scene IR, and every backend is a pure serializer of that scene — which is why adding a format never touches the language.

flowchart TD
    SRC["<b>.arch</b> source"] --> LEX["<b>lexer</b><br/><i>hand-written → tokens with byte spans</i>"]
    LEX --> PAR["<b>parser</b><br/><i>recursive descent → AST · recovers, never throws</i>"]
    PAR --> IR["<b>resolve()</b><br/><i>expand scripting · grid-snap<br/>relational placement · host openings</i>"]

    IR -->|"render"| SCN["<b>toScene()</b><br/><i>wall union · hatches · page</i>"]
    IR -->|"read back"| DESC["<b>describe() · lint() · validateIntent()</b><br/><i>the SAME resolved plan, as FACTS —<br/>no rendering required</i>"]

    SCN --> SVG["<b>SVG</b><br/><sub>zero-dep</sub>"]
    SCN --> DXF["<b>DXF</b><br/><sub>zero-dep</sub>"]
    SCN --> TXT["<b>TXT</b><br/><sub>zero-dep</sub>"]
    SCN --> PDF["<b>PDF</b><br/><sub>optional</sub>"]
    SCN --> PNG["<b>PNG</b><br/><sub>optional</sub>"]

    DESC --> FACTS(["rooms · areas · adjacency<br/>access graph · intent score"])

    style SRC fill:#ede7f6,stroke:#6b3ae0,color:#1a1a1a
    style IR fill:#eceef2,stroke:#464d59,color:#1a1a1a
    style SCN fill:#eceef2,stroke:#464d59,color:#1a1a1a
    style DESC fill:#e8f5e9,stroke:#2e7d32,color:#1a1a1a
    style FACTS fill:#e8f5e9,stroke:#2e7d32,color:#1a1a1a
    style SVG fill:#fbfbfc,stroke:#464d59,color:#1a1a1a
    style DXF fill:#fbfbfc,stroke:#464d59,color:#1a1a1a
    style TXT fill:#fbfbfc,stroke:#464d59,color:#1a1a1a
    style PDF fill:#fbfbfc,stroke:#8a8f98,color:#1a1a1a
    style PNG fill:#fbfbfc,stroke:#8a8f98,color:#1a1a1a

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The dotted branch is the point: describe, lint and the intent check read the same resolved plan the renderer does — so what an agent verifies is exactly what gets drawn, and it costs no pixels to check.

compile() is pure, synchronous and deterministic — no I/O, no Date.now(), no Math.random(). The only place Node APIs are allowed is the CLI; everything else gets its environment through a World seam. See AGENTS.md and the ADRs.

📦 Ecosystem

Package / surface	What it is
@chanmeng666/archlang	The core: compiler, CLI, analysis. Zero runtime deps, isomorphic.
@chanmeng666/archlang-mcp	Optional stdio MCP server (the SDK is quarantined here).
VS Code extension	Syntax + live diagnostics, hover, completion, rename.
Playground	Client-side editor: preview, describe, lint, intent scoring, apply-fix, embed.
Docs site	Guide, reference, CLI reference, ADRs, live examples.
🤗 Dataset	Synthetic, self-verifying repair trajectories + authoring pairs. CC0.
GitHub Action	Render ```arch fences in any repo's Markdown.

Embed a plan anywhere

A live, editable plan in any blog, wiki or docs page — one <iframe>, no build step, nothing sent to a server (the source rides in the compressed #z= hash, so the page is self-contained):

<iframe src="https://archlang-playground.vercel.app/embed.html#z=…" width="720" height="480"></iframe>

The playground's Embed button generates the snippet. Optional params: editable=1 (show a compact editor that re-renders as you type) and theme=blueprint|dark|mono|presentation.

Not on GitHub, though. GitHub's markdown sanitizer strips <iframe> — it renders as escaped text, the same way <script> does — so a README (here or anywhere on github.com) cannot host a live embed, no matter how it's written. The honest substitutes GitHub does allow are what this README uses: a static SVG the compiler really produced, linked to a playground permalink that opens the same plan live. On the docs site, where the sanitizer doesn't apply, every plan is live and editable in place.

📚 Documentation

• 📖 Docs site — guide, reference, error catalog, ADRs, and a live, editable examples gallery. Every ```arch fence on a docs page is itself an editable plan.
• ⌨ CLI reference — every command, flag and exit code (generated from the manifest, so it can't fall behind).
• spec.llm.md — the whole language in one page (~2k tokens) for AI agents; also arch spec.
• SKILL.md — the agent Skill: the spec → compile → fix → describe → validate loop.
• Language Reference · Error catalog · The intent contract · ADRs
• AGENTS.md — orientation for AI agents working in this repo.

🤝 Contributing

Contributions are welcome! Please read the Contributing Guide and our Code of Conduct. Use the issue and pull-request templates when you open one.

❤️ Support & Sponsor

• Questions? Open a Discussion or see SUPPORT.md.
• Found a security issue? Follow SECURITY.md.
• If this project helps you, consider sponsoring ☕.

📄 License

Released under the MIT license.

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Chan Meng
Need a custom app like this one? I build them — let's talk.