run now feeds coordinate tokens to interactive tools: "LINE 0,0 10,10" starts the tool, feeds the points, and terminates as if Enter were pressed — creating real geometry through the existing command system. The headless session also leaves the welcome (Start) tab so drawing commands aren'\''t blocked. Verified end-to-end: LINE/CIRCLE create entities that save and reopen. Co-Authored-By: Claude Opus 4.8 <[email protected]>
Headless automation API
Open CAD Studio can run without a GUI and be driven over a line-based JSON protocol — for scripts, batch jobs, or AI agents.
OpenCADStudio --serve
It reads one JSON request per line on stdin and writes one JSON response per line on stdout. The active document persists across requests, so a caller can act → observe → act.
Protocol
| Request | Response |
|---|---|
{"op":"new"} |
{"ok":true,"total":0,"by_type":{}} |
{"op":"open","path":"plan.dwg"} |
entity summary |
{"op":"run","cmd":"LAYER Walls"} |
{"ok":true,"cmd":...,"entities":N,"added":D} |
{"op":"entities"} |
{"ok":true,"total":N,"by_type":{"Line":42,...}} |
{"op":"save","path":"out.dwg"} |
{"ok":true,"saved":"out.dwg"} (path optional once opened/saved) |
Every response has "ok"; failures carry "error". run drives Open CAD
Studio's own command system — no separate bindings to maintain — so its
coverage grows with the app.
Interactive draw commands take their points as coordinate tokens; the tool is started, the points are fed, and it is terminated as if Enter were pressed:
{"op":"run","cmd":"LINE 0,0 10,10 10,20"} → two Line segments
{"op":"run","cmd":"CIRCLE 5,5 3"} → centre 5,5 radius 3
Coordinates are x,y or x,y,z; @dx,dy is relative to the previous point.
Inline-argument commands (PDMODE 3, LAYER Walls) are passed through as-is.
Coverage is growing: commands whose options are typed keywords or coordinates work; ones that still rely on on-screen picking (object selection by clicking) are being wired next.
Python client
ocs.py is a ~100-line client — nothing to compile:
from ocs import Ocs
with Ocs(binary="OpenCADStudio") as ocs: # spawns `--serve`
ocs.open("plan.dwg")
ocs.run("LAYER Walls")
print(ocs.entities())
ocs.save("plan_out.dwg")
Any language can speak the same protocol over a subprocess pipe.