- a download button in the header opens the web app's export dialog
(.drawio, .png, .svg, .drawio.svg), which the classic page had and the
shell lacked when it became the default
- the shell asks draw.io for the custom library menu (libraries=1), as
the classic page did; the web app keeps libraries=0
- the newest card no longer shows "Rendering preview" for good: the sync
takes the thumbnail of a diagram the server recovered from its file
(saved without pictures) while the canvas kept it, and of a write whose
picture was skipped because an edit came first, once the canvas shows
the write again
- e2e: the get_selection test covers a shape in a container the user
entered; a download test saves a .drawio file
The shell's VersionsSource (shell/node-versions-source.ts) reads GET
/api/history through the sync and shows one version per distinct content
(a restore's copy folds into the entry it copies; the blank page is none),
numbered as they first appeared, with what changed since the one before.
The entry the server says is on the canvas marks the version; undo and
redo of the newest version restore the one before it, or it again, through
POST /api/restore, so hand edits stay as versions of their own. The cards
sit in a panel beside the canvas (toggle in the header); the strip and
Compare come from the shared canvas components. The sync tells listeners
once per server version, and when History changed without one, so the
list is read again only then.
The stalled-tab note names the page start_session opened (the shell
with DRAWIO_PREVIEW_UI=shell) instead of the classic page. With the
shell not built, start_session opens the classic page and the server
says so at startup, as it does for a missing dist/drawio. BROWSER=none
skips the system browser, as Vite and CRA dev servers do: the e2e tests
set it. Without a fixed DRAWIO_UI, the shell's draw.io URL carries
themes=1 so Extras > Theme is offered, as on the classic page.
shell/mcp-sync-core.ts ports preview.js's protocol without the page or
React: polling GET /api/state every 2 s with the state id and version,
pushes of the user's edits with their base version and state, 409 and 413
handling, recovery of a recreated session (the tab's copy goes to History),
the token refresh after a 403, sync and export requests (PNG by page id,
SVG of another page through a transient one-page projection with autosave
ignored, the 600 ms wait for icons), thumbnails for History, and History
reads and restores that name the state the list belongs to.
A server write goes on the canvas as one undo step (loadDiagram commit,
with the change marked) when decideLoad finds it changes only the page on
screen, keeps the file variables and needs no load-only setting; the other
pages are compared with the MCP core's contentFingerprint. draw.io's own
re-serialized copy of such a write is recognized with isSameDocument and
not pushed back as an edit.
shell/use-mcp-sync.ts mounts the sync once inside DiagramProvider, reads
draw.io's autosave and load messages, and reports the connection state,
which the shell's status bar shows; notices come as toasts from the
dictionaries.
The shell (packages/mcp-server/shell) renders DrawioFrame inside the
shared providers without the chat: its config comes from
window.__MCP_CONFIG__, the four dictionaries ship in the bundle, the
theme is kept under an mcp: localStorage key, and system fonts stand in
for the web fonts. scripts/build-shell.mjs bundles it into dist/shell
with the root's esbuild and Tailwind; check-package caps shell.js at
1.5 MB and shell.css at 300 KB.
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