usage: dg <command> [flags]

commands:
  check       validate the project
  fmt         format the project's files
  export      draw a view, or every view, as SVG, PNG, GIF or JSON geometry
  serve       show the views in the browser, redrawn when a file changes
  vocabulary  print the kinds, edge kinds, tags and views the project defines, as JSON
  op          apply an operation to the project's files (dg op --help lists them)
  mcp         serve the Model Context Protocol over standard input and output
  lsp         serve the Language Server Protocol over standard input and output
  version     print dg's version

coding agents: read https://raw.githubusercontent.com/nvcnvn/dg/main/skills/dg/SKILL.md before using dg

In a VS Code terminal with the extension installed, dg is already on the PATH. Elsewhere, install the command line.

Every command takes -C <dir>, the project directory (default: the current directory). Flags take one dash or two: -json and --json are the same.

Exit codes are the same for every command: 0 when it succeeded, 1 when the project has errors or the input is invalid (an operation refused, a flag wrong), and 2 when dg itself failed, such as an unreadable directory or a browser that does not start.

dg check

Flag Value Meaning
-C string project directory (default “.”)
--json   print diagnostics as JSON
--strict   treat warnings as errors

Validates the whole project and prints one line per diagnostic, sorted by file, line and column:

model.hcl:13:12: error: Undefined node: Parent "backnd" of node "api" is not defined.

Severities are error, warning and info. --strict fails on warnings too, never on information. --json prints a JSON array of objects with severity, summary, detail and, when there is a position, file, line, column, end_line and end_column. file is relative to the project; diagnostics about the built-in pack name <generic>/spec.hcl or <generic>/style.hcl.

dg fmt

Flag Value Meaning
-C string project directory (default “.”)
--check   list the files that would change and write nothing

Formats every writable HCL file the project loads in HCL’s canonical style, and rewrites layout files in their canonical form, all files together. It prints the path of each file it changed. read_only files are skipped, files that do not parse are reported and left alone, and nothing is written while dg.hcl has errors. --check lists the files that would change, writes nothing, and exits with 1 if there are any.

dg export

Flag Value Meaning
-C string project directory (default “.”)
--all   export every view into the –out directory, one <view>.<format> file each
--format string output format: svg, png, gif or json (default “svg”)
--out string output file, or directory with –all (default standard output)
--scale float pixels per unit of a PNG, from 1 to 8 (default 1)
--view string view to export (default “main”)

Draws a view in headless Chrome or Chromium, which must be installed, exactly as the editor draws it, without the editor’s selection, fading or drill-down badges. On Windows it falls back to Edge. No other browser works: with none of these installed, the command fails and says so.

Format Output
svg an SVG file; animated edges keep their animation as CSS. Text names the font (Inter, sans-serif) without embedding it
png a picture on white, one pixel per unit or --scale pixels, animations at their start
gif one half-second animation period in 10 frames, looping
json the geometry: each node’s box, port positions and row lines, each edge’s route, in canvas coordinates; and each node’s frame and its position rel in it, as move takes them, or ordered_in, the stack or grid that places it 
dg export -C examples/hello --format svg --out hello.svg
dg export -C examples/c4-container --view sign-in --format gif --out sign-in.gif
dg export -C examples/c4 --all --format png --out pictures

--all writes one <view>.<format> file per view into the --out directory, and nothing unless every view can be drawn. Without --out, the picture goes to standard output. Exporting is deterministic: the same files give the same bytes.

dg serve

Flag Value Meaning
-C string project directory (default “.”)
--addr string address to listen on (default “127.0.0.1:0”)
--open   open the editor in the browser (default true)
--stdin   stop when standard input closes, as when the editor that started dg serve exits

Starts the editor on a local address, prints it (dg serve: http://127.0.0.1:…/) and opens it in the browser. The editor redraws within a fraction of a second when a project file changes on disk. While the project has errors it lists them and keeps showing the last good drawing, read-only. Stop it with Ctrl+C.

dg serve listens only on the loopback address and has no authentication. Several browser windows can edit one project; they share one undo history.

dg op

Applies one operation to the project’s files: the same changes the editor makes, for scripts and agents. dg op --help lists the operations and dg op <operation> --help shows one’s flags.

dg vocabulary

Flag Value Meaning
-C string project directory (default “.”)

Prints, as JSON, what a project can be built from: its packs in load order, its kinds (with the pack that defines each, their ports, properties and whether they are containers or hold rows, inherited ones included), edge kinds, tags and views. Agents read it before writing a model.

dg mcp

Flag Value Meaning
-C string project directory (default “.”)

Serves the Model Context Protocol over standard input and output, for agents. It has four tools, each giving the same result as its command:

Tool Does
check the diagnostics, as dg check --json
vocabulary the kinds, edge kinds, tags and views, as dg vocabulary
op applies an operation given as a JSON object, batch included; the result is dg op --json’s, an error result when refused
export draws a view: {view?, format?}; PNG (the default) and GIF are returned as images the agent can see, SVG and JSON as text

To use it from an MCP client, add dg mcp -C /path/to/project as a stdio server. An agent started in a VS Code terminal finds the extension’s dg; a client that starts dg from anywhere else, VS Code’s own MCP servers included, needs the command line installed. One server serves one project. Without -C it serves the directory the client starts it in. Most clients take this JSON:

{
  "mcpServers": {
    "dg": { "command": "dg", "args": ["mcp", "-C", "/path/to/project"] }
  }
}

VS Code’s .vscode/mcp.json names the key servers and can use the workspace’s folder:

{
  "servers": {
    "dg": { "type": "stdio", "command": "dg", "args": ["mcp", "-C", "${workspaceFolder}"] }
  }
}

A client started from the desktop may not have your shell’s PATH: if it cannot find dg, give command the full path, such as /home/you/.local/bin/dg or C:\Users\you\.local\bin\dg.exe. The export tool needs Chrome or Chromium, as dg export does.

dg lsp

Flag Value Meaning
-C string project directory (default “.”)

Serves the Language Server Protocol over standard input and output for the project’s HCL files, working on the editor’s unsaved text: diagnostics, completion, hover, go to definition, find references, rename and formatting. The VS Code extension runs it; other editors can run dg lsp -C <project> for .hcl files.