Psalmustrack/lambdacad-mcp

**Let AI draw in your CAD.**
An MCP server for **any AutoLISP-capable CAD** — no COM, no SDK, no plugins. Pure AutoLISP.
The reference adapter drives **BricsCAD on Linux**: the first MCP server for a professional DWG CAD on Linux.
> *"Draw a DN80 flange: front view, hatched section, dimensions — then model it in 3D."*
*Real-time capture, unedited: front view with bolt circle, hatched section, radial/diameter dimensions, leader, title block — then the same flange modeled as a 3D solid with an AI-written parametric AutoLISP loop and one boolean subtraction. ~20 seconds, 12 tool calls.*
| Complete 2D drawing, drawn by Claude | 3D solids with booleans | Clean render for AI vision |
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Why this exists
Every other MCP server for a professional DWG CAD (multiCAD-mcp, autocad-mcp, CAD-MCP, ...) talks to the CAD through **Windows COM** — none of them can run on Linux, and none of them does real 3D.
BricsCAD is the professional DWG CAD that *does* run natively on Linux. This server drives it through a mechanism that needs no API at all: an **AutoLISP file bridge**. The MCP server writes LISP expressions to a file, triggers a tiny MCP command inside the CAD, and reads the result back. That's the whole trick — and it unlocks everything the CAD can do, including 3D solid modeling.
Because the bridge is plain AutoLISP + standard DXF entmake + AutoCAD-compatible commands, it is **portable by construction**: AutoCAD, ARES Commander (also Linux-native!), ZWCAD, GstarCAD and the IntelliCAD family all speak the same language. Porting means swapping the autoload file name and the keystroke trigger — **adapters welcome**.
What it can do
- **Full 2D drafting** — lines/arcs/polylines/splines, **line weights per layer** (0.50 walls / 0.35 edges / 0.18 dimensions — measured on the plotted page, not just set), real HATCH (with islands), dimensions incl. radius/diameter/angular, leaders, linetypes (chain/hidden), text styles, trim/extend/fillet/chamfer/offset/mirror/arrays, blocks
- **Semantic shapes** — slot, bolt_circle, rounded_rect, polygon, center_mark: one call, the server does the math
- **3D solid modeling** — box/cylinder/sphere/cone/wedge/torus, **extrude/revolve/sweep**, **union/subtract/intersect**, slice, **fillet/chamfer on solid edges**, **3D move/rotate around any axis** — and **flatshot_view**: auto-generate correct 2D drawing views from the 3D model
- **Batch & atomic** — draw_batch executes N operations in one round-trip, wrapped in one undo group (**one batch = one Ctrl+Z**)
- **Talk about what the user selected** — get_selection reads the GUI pickfirst set; select_by/select_window highlight what the AI found *before* acting; modify tools accept "selection"
- **Verification without screenshots** — bounding boxes, key points, exact lengths/areas, **intersection checks** (collision detection), solid volume/centroid
- **Design review — tools that answer an engineering question, not just run a command** *(new in 1.2)* — boolean_verified cuts *and measures* the change against the volume you expected (a cut that lands short reads SHORT, not success); overhang_report reads the STL mesh and says whether a part prints without supports, scoring all six orientations; contact_report over an **assembly** (assembly_place/assembly_list/assembly_clear) says who touches whom, who interferes, and who is an **orphan** — a part touching nothing, because its job was superseded and nobody noticed; hole_report physically probes every hole and says which are actually open (a drawing lies about its holes until something checks); graph_build/graph_trace read the 2D geometry as a connectivity graph — separate networks, exact run lengths, and the open ends that are real breaks vs T-junctions, with the joining tolerance *emerging from the drawing* instead of hardcoded