dsh-drawio-chat

The chat-first draw.io plugin for DeepSeek Harness. The model creates, inspects and edits native .drawio files, the chat renders them with the real draw.io viewer, and every diagram stays in the workspace.

• No draw.io account, no npx MCP server, no local editor install.
• Rendering happens inside a sandboxed iframe (opaque origin), so model-generated XML never touches the GUI origin.
• drawio_reference fetches draw.io's official XML reference from https://mcp.draw.io/mcp (no auth); the diagram itself is never uploaded, with a built-in condensed fallback.
• Tools only touch .drawio files under the session workspace; writes are atomic.

Feature overview

Draw — flowcharts, architecture, UML, ER, network topologies, wireframes and other draw.io shape libraries; multi-page diagrams, layers, containers and swimlanes; LaTeX typesetting in labels.

Edit — drawio_read returns the structure by id/geometry/style plus the current revision; drawio_apply batches semantic ops (labels, styles, add/remove nodes and edges, move, z-order) with atomic writes and a revision-conflict guard; drawio_undo restores any of the last 8 versions of a file.

View — an interactive draw.io viewer in the transcript (zoom, pan, layers, page navigation), and .drawio files open in the right sidebar tab instead of showing raw XML.

Export — download the .drawio, export SVG or 2× PNG, or open it in draw.io. Files are saved under diagrams/ and can be committed with the repository.

Scope — built for structural, flow, architecture and teaching diagrams. Not for 3D interactive courseware or video: those need a different plugin or pipeline.

Install

After publishing: dsh plugin --profile web add dsh-drawio-chat (or install from the desktop marketplace). For a local build (the desktop app owns the desktop profile, quit it first):

pnpm install && pnpm build
node scripts/install-into-desktop-profile.mjs --dry-run
node scripts/install-into-desktop-profile.mjs

Restart the app, then ask the model to "draw a login flow diagram": it calls drawio_create, a draw.io viewer appears in the transcript, and the file lands under diagrams/. Follow-ups such as "rename the Home node" use drawio_read + drawio_apply; "undo that" uses drawio_undo.

Known limits

• XML input only (mxGraphModel/mxfile); Mermaid input is not supported yet.
• The inline viewer script is loaded from https://viewer.diagrams.net (no account; first render needs network). An offline vendor pack is planned.
• No 3D or video output — see Scope above.

Verification

pnpm typecheck, pnpm test (13 files / 50 tests) and pnpm build pass; inline rendering was verified with a headless-browser screenshot (.harness/assets/viewer-sandbox-proof.png), and SVG/PNG export were verified end-to-end in headless Chrome (PNG: 2400×1600 canvas, 84,368 bytes, no canvas taint).