pac-vector

Local stdio MCP server: an SVG editor over in-memory virtual documents (one per "window", like Inkscape), with a live browser preview of every edit.

• Content goes in as SVG markup; structure (layers, groups, masks, z-order) has typed tools.
• Layers are real Inkscape layers, so exported files open in Inkscape with layers intact.
• Path booleans (union, difference, intersection, exclusion, division) via Skia PathOps.
• Every edit is atomic (a failed call changes nothing), one undo/redo step, and autosaved: windows of a crashed session reopen in the next one.
• render returns a PNG the agent can look at; rendering is resvg (no browser, no Cairo).

Install

Same shape as pac-pincers: a pip package, run as a module by whatever Python it was installed into.

python -m pip install --upgrade pac-vector
claude mcp add pac-vector --scope user -- python -m pac_vector

As a plugin .mcp.json entry (mirrors the datatopia plugin's pac-pincers entry):

"pac-vector": {
  "type": "stdio",
  "command": "${PAC_VECTOR_PYTHON:-python}",
  "args": ["-m", "pac_vector"],
  "env": {}
}

Development:

python -m venv .venv
.\.venv\Scripts\python.exe -m pip install -e ".[dev]"
.\.venv\Scripts\python.exe run_tests.py -q
.\.venv\Scripts\python.exe -m build          # dist/pac_vector-<ver>.tar.gz + .whl

Tools (21)

Preview

doc_create / doc_list / inspect print preview: http://127.0.0.1:<port>/#<doc>. The page has a tab per document, outlines the elements each edit touched, and shows (and copies) the id of anything you click. The server lives inside the MCP process: it starts on the first doc_create and dies with the session.

Environment

Notes

• stdout is the JSON-RPC pipe: nothing may print to it. tests/test_stdout_safety.py scans the package for print() / sys.stdout, and tests/test_stdio.py runs a real session.
• Native modules are loaded before the stdio loop starts (render.warm): on Windows a first native load from inside the FastMCP loop can hang (see pac-pincers' _excel.py).
• Bounding boxes are measured from pixels (two-pass render), so they include strokes and filters and work for text and curves; content further than two page-widths off-canvas isn't found. align uses them, so it aligns what you see.
• Booleans use fill geometry only (strokes, text and images don't take part); the result is a <path> in the bottom operand's place, styled like it, keeping its id.
• Animations are SMIL: the browser preview plays them; render / PNG export show the static first frame.
• Version lives only in pyproject.toml; a release is a commit named after the version.