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cadcraft/docs/control-protocol.md
T
by TruittandClaude Opus 5.5 c87a38546c Default save format for new drawings (DXF or DWG) (#298)
Save As suggested `.dxf` for every untitled drawing, so saving new work as
DWG meant typing the extension each time. AutoCAD keeps this choice in
Options > Open and Save > "Save as".

- File > Default Save Format > DXF / DWG sets the format Save As suggests
  for drawings that have no file yet. Drawings opened from a file keep that
  file's format, as before. DXF stays the default.
- The choice is saved across restarts with the other preferences
  (`saveFormat`), survives Reset Palettes, and is scriptable as
  `ui.saveformat {format}` or the `saveFormat` UiState field.
- Ukrainian labels for the new menu entries.

On macOS the suggested `.dwg` name needs DWG in the Save As filter list
(#198) to survive the dialog.


Claude-Session: https://claude.ai/code/session_019uMCkRAB8DMd8MEmoY9Vyr

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-10 16:11:46 -04:00

3.6 KiB

CADCraft control protocol

Start the desktop app with --control PORT (or CADCRAFT_CONTROL_PORT=PORT). It listens on 127.0.0.1:PORT for JSON lines: one request per line, one reply per line.

{"id": 1, "method": "cmdline.input", "params": {"text": "circle 0,0 5"}}
{"id": 1, "ok": true, "result": {"prompt": "Command:", "output": ["Command: CIRCLE"], ...}}

Errors come back as {"id": …, "ok": false, "error": "message"}.

Method Params What it does
cmdline.input {text} Type a line at the command line exactly like a user. Starts commands by name/alias and answers prompts (points x,y, @dx,dy, @d<a, distances, keywords, empty = Enter). Spaces act as Enter except at text prompts.
cmdline.script {text} Run a multi-line script (like .scr files).
cmdline.key {key: "enter"|"escape"} Press Enter or Escape.
cmdline.state Current prompt, keywords, accepted input kinds, history tail.
engine.execute {command, params} Run any command with JSON parameters. Never opens a dialog.
engine.commands Every command: id, label, menu path, shortcut, aliases, params doc, enabled.
drawing.inspect {entities?, limit?} Drawing summary (counts, extents, layers, styles, blocks, layouts, selection, undo) and entities with handles and geometry.
ui.inspect UI state, canvas rect, view, cursor and snap, performance counters; closePrompt: the drawing a "Save changes?" prompt is asking about (null when none).
ui.menu.list / ui.menu.invoke {command} The menu tree; invoke an item like a click (interactive).
ui.pointer {x, y, space?: "world"|"screen", button?, action?: "click"|"move"} Click in the drawing area (world coordinates by default). Right button = Enter.
ui.click / ui.move {x, y, button?, shift?} Real egui pointer events in screen points (reach every widget).
ui.drag {x, y, to: [x, y], button?} Real press, move and release (drag the command line's top edge, the ViewCube ring…).
ui.key / ui.text {key, cmd?, shift?, alt?} / {text} Synthetic keyboard input.
ui.set UiState fields Show/hide palettes, toolbars, command line, ViewCube…; theme: "system"|"light"|"dark" (also engine.execute with ui.theme {theme}); ui.inspect reports the theme shown (theme: light/dark). saveFormat: "dxf"|"dwg" (also ui.saveformat {format}) is the format Save As suggests for new drawings.
ui.resize {width, height} Resize the window.
ui.screenshot {path?} PNG of the window (needs a presented frame).
ui.render {path?, width?, height?, fit?} Headless render. fit (default true) frames the whole drawing; false uses the current view. Replies {pngBase64, width, height, bytes, path?}.
app.open / app.save / app.quit {path} File operations.

The MCP server (cadcraft-cli mcp --connect 127.0.0.1:PORT) wraps this protocol; headless (cadcraft-cli mcp) it serves the same methods from an in-process session.

Interface language

Select a language with engine.execute and the UI command ui.language:

{"id":1,"method":"engine.execute","params":{"command":"ui.language","params":{"lang":"uk"}}}

Supported values are auto, en and uk. ui.set also accepts {"interfaceLanguage":"uk"}; ui.inspect reports the saved choice in its UI state. Invalid choices leave the current language unchanged. Menus, command labels and prompt text returned by the control channel retain their English source text. See localization.md.