Self-hosted draw.io diagram editor extension for piclaw. Add-on 31.4.4 contains draw.io v31.4.2; add-on fixes do not change the pinned vendor version.

Requires Piclaw >=1.8.0.

Install

Open Settings → Add-Ons and install drawio-editor from the catalog.

What it does

• Registers an HTTP route at /drawio/* serving the draw.io webapp in embed mode
• Provides the open_drawio_editor tool for the agent
• Opens .drawio, .drawio.xml, .drawio.svg, .drawio.png, and .xml workspace files
• Auto-creates a missing target file when opened through open_drawio_editor
• Supports PNG, JPG, and SVG export from the reduced export menu
• Saves through POST /drawio/save and supports read-only attachment/media preview

Multi-page previews

Read-only attachment previews show page tabs above the drawing. Click a tab or use Left/Right, Home and End while a tab is focused. Long tab rows scroll horizontally; single-page drawings do not show an unnecessary tab row. Page names are displayed as text, not interpreted as HTML.

Navigation uses the bundled editor's decoded page list, including compressed .drawio files and editable-diagram data embedded in SVG/PNG attachments. The iframe interaction lock stays active and the graph is disabled; page selection does not create undo edits or send saves. Workspace editing and exports remain separate and unchanged. Image files without embedded diagram data cannot acquire extra pages from their rendered pixels.

Read-only startup waits for the trusted editor-ready message rather than polling vendor prototypes. A single 15-second deadline reports a stalled load; a missing page API reports an unavailable-preview error without enabling editing. Closing the preview cancels the deadline and ignores late load/message callbacks.

The optional preview-pages.browser.test.ts runs the real vendored application against disposable loopback fixtures. Set PICLAW_E2E_DISPOSABLE=1, PICLAW_DRAWIO_CORE_SOURCE=/absolute/path/to/piclaw and an installed PLAYWRIGHT_BROWSERS_PATH, then run it with Bun from the repository root.

Vendor files

The public add-on tarball includes the self-hosted draw.io webapp. It does not download editor code during installation.

Maintainers update the bundle from the official upstream WAR with:

bun run --cwd addons/drawio-editor vendor:update

The refresh script uses piclaw.vendorVersion for the upstream tag, verifies the pinned WAR SHA-256, copies the browser client subset, checks EditorUi.VERSION and mxClient.VERSION, and writes vendor/drawio.meta.json.

Architecture

Uses piclaw's globalThis.__piclaw_registerRoute to serve the draw.io webapp. A wrapper page at /drawio/edit?path=... (also accepted as /drawio/edit.html) embeds the editor in an iframe and handles the postMessage protocol for load/save via the piclaw raw file API.