Battenmark

Open, backend-neutral CAD infrastructure for AI agents and software.

Battenmark provides a typed, backend-neutral interface for creating, editing, inspecting, validating and exporting authoritative CAD geometry across interchangeable CAD backends. Callers request create_hole — never PartDesign::Hole. No transport owns the model; one canonical service does.

ChatGPT / Claude / Gemini / Grok / Codex / local models / IDE agents / custom apps
                                   │
                    MCP / HTTP / Python / CLI
                                   │
                                   ▼
                         Battenmark Core
                                   │
                    typed CAD operations / CAD IR
                                   │
                        Backend Registry
                                   │
             ┌─────────────────────┼──────────────────────┐
             ▼                     ▼                      ▼
          FreeCAD                JSCAD              future adapters
     authoritative B-rep        preview        build123d/CadQuery/etc.

• FreeCAD / OpenCascade — authoritative B-rep kernel (headless JSON-lines worker)
• JSCAD — in-process preview/envelope backend (not the source of truth)

Quickstart

Prerequisites: Node.js ≥ 20 and npm. FreeCAD is optional for the core service and required only for the authoritative B-rep backend.

npm install
npx tsc --noEmit   # type check
npm test           # fast kernel-free suites (parametric, selectors, registry)

FreeCAD backend

sh scripts/bootstrap-macos.sh      # macOS: discovers /Applications/FreeCAD.app
sh scripts/install-freecad.sh      # Linux: installs headless 1.0.2 AppImage (no FUSE)
npm run test:freecad               # proves the real worker end-to-end

Discovery order: $AGENTCAD_FREECAD_CMD → macOS FreeCAD.app bundles → Homebrew → extracted Linux AppImage → PATH. See docs/MACOS.md and docs/LINUX.md.

Transports

Transport	Entry point
MCP stdio	npx agentcad-mcp
HTTP	npx agentcad serve --port 8787 then /api/v1/... (Bearer token via AGENTCAD_API_TOKEN)
CLI	npx agentcad --help
Python	python/agentcad — see examples

Python client example:

from agentcad import AgentCad

c = AgentCad(base_url="http://127.0.0.1:8787", token="secret-token")
pid = c.project_create("demo")["project_id"]
c.create_box(pid, 80, 50, 12)
print(c.rebuild(pid)["data"]["volume_mm3"])   # 48000

Golden smoke model

The canonical release smoke test is an 80 × 50 × 12 mm box = 48,000 mm³, verified through JSCAD, FreeCAD, HTTP, CLI, MCP and the Python client (test:transport-parity). Do not change this fixture casually.

Capabilities

• Backend-neutral typed CAD operations with explicit schema (agentcad_schema_version: 2)
• FreeCAD/OpenCascade authoritative B-rep; JSCAD preview
• Scalar parameter expressions and dependency evaluation
• Semantic face/edge selectors (top_perimeter, …) that re-resolve after edits
• Persistent geometry references (gref) with explicit lost/ambiguous errors
• Through / blind / counterbore / countersink holes
• Fillets and chamfers · linear and rectangular patterns
• STEP / FCStd / STL interchange · four-view PNG previews
• Dynamic backend registry with per-backend capability discovery
• One serialized FreeCAD worker with kill/restart recovery
• Assemblies: component definitions, persistent instances, grounded frames, face mates, axis/concentric alignment, distance & angle constraints (see docs/ASSEMBLIES.md)

Platform status

Platform	Status
macOS Apple Silicon	Tier 1 — hardware verified (arm64, macOS 26.6.2, FreeCAD 1.1.3)
Linux x86_64	headless / development validated (FreeCAD 1.0.2 AppImage)
macOS Intel	unverified
Windows	unsupported / unverified

Known limitations

This is pre-1.0 alpha software; APIs may change.

• No assemblies, mates or assembly constraints yet
• No circular patterns
• Threads are cosmetic metadata, not helical solids
• Imported STEP is geometry import — not automatic parametric reconstruction
• Native FCStd documents keep historical PartDesign feature shapes; Battenmark measures the final Body Tip (summing historical solids double-counts)
• One serialized FreeCAD worker (no pooling)
• Preview rendering is JSCAD, not OCC hidden-line
• Complete topological naming is not solved; persistent gref mitigates it

Full list: docs/LIMITATIONS.md.

Documentation

Topic	Doc
Architecture & foundation	docs/ARCHITECTURE.md · docs/FOUNDATION.md
Operation contract & schema	docs/CONTRACT.md · docs/VERSIONING.md
Backends & kernels	docs/BACKENDS.md · docs/FREECAD.md · docs/JSCAD.md · docs/KERNEL.md
Transports	docs/MCP.md · docs/HTTP.md · docs/CLI.md · docs/PYTHON.md · docs/CLIENTS.md
Service & persistence	docs/SERVICE.md · docs/AUTH.md
Import / export & preview	docs/IMPORT.md · docs/PREVIEW.md
Platforms & validation	docs/MACOS.md · docs/LINUX.md · docs/RELEASE.md

Compatibility identifiers

Public branding is Battenmark. Historical engineering identifiers remain on purpose and are a compatibility surface, not a second brand: AgentCadService, agentcad_schema_version, AGENTCAD_* environment variables, the agentcad / agentcad-mcp binaries. The internal service version 0.5.6 intentionally differs from the release tag; see docs/VERSIONING.md.

Contributing & security

See CONTRIBUTING.md and SECURITY.md. Code of Conduct: CODE_OF_CONDUCT.md.

License

Apache-2.0 for this repository. FreeCAD/OpenCascade are invoked as a separate LGPL process (the worker scripts run inside FreeCADCmd). See LICENSE, NOTICE and THIRD_PARTY_NOTICES.md.