The reminder step left out the root lockfile and scripts/, which change
what is bundled into the shell and trigger the publish workflow; and it
took any change of packages/mcp-server/package.json (a dependency bump)
for a version bump. It now compares the version field between the two
commits.
- 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
Server (src/http-server.ts, src/index.ts, src/selection.ts,
src/new-diagram.ts):
- overlapping get_selection calls take turns (readSelection, one slot per
session as the export slot) instead of replacing each other's request,
which left one of them with a false "tab not in front" timeout
- an answer is taken only while a request is pending (both ids undefined
compared equal)
- the tool sees the page start_session actually opens: with dist/shell
missing the classic page is in use, which never answers, so the tool
says so instead of timing out
- the result lists at most 100 cells and counts the rest: a whole large
diagram selected would fill the model's context
- every <diagram> the model sends without an id gets one, so the page id
the shell reports exists in the server's document
Shell (shell/mcp-sync-core.ts, shell/use-mcp-sync.ts,
contexts/diagram-context.tsx, lib/drawio/editor-bridge.ts):
- an answer whose POST failed is sent again at the next poll
- no answer while a full load has yet to reach the editor: it still shows
the previous document, whose cells and pages the answer would name
- a hidden tab (the same session open twice) answers a poll later, so the
tab in front answers first; alone, it still answers within the timeout
- a cell's container is reported by the model's isLayer, not by comparing
with the default parent, which is the group the user entered
The shell's version cards (shell/node-versions-source.ts):
- a version's change and undo target are the state it replaced, the
History entry right before its first copy, not the card before it: after
a restore those differ, and undo went to the wrong version (and not
where restore_version steps_back=1 goes)
- a card restores the newest copy of its content, as restore_version
does, so page settings the user changed (a "user" copy) are kept
- a blank page after a drawing is a clear of the canvas, a version of its
own; only the blank page before any drawing is hidden
- numbers and changes are keyed by content, not by the first copy's id,
so a version keeps them when its first copy drops out of the server's
20-entry buffer; the caches start over for another server state (the
process restarted: entry ids name other content)
The server's History (src/history.ts):
- firstCopyIds compares each entry with the first of every group only: a
bare model matches any page name, so "same content" is not transitive,
and a card could show one document and restore another
- the time and pages fields had no reader; pages parsed every XML once
more on every write
Reading History (src/http-server.ts, shell/mcp-sync-core.ts):
- GET /api/state and a push's answer carry a History key (entry count,
newest id, the entry on the canvas); the shell reads History again only
when it changes, so a hand edit no longer downloads every entry's XML and
thumbnail
- a failed History read is told again at the next poll
- a History list from a state the poll has not seen yet is dropped
Unit tests for the request plumbing (random id, one answer, timeout), the tool's texts (cells, nothing selected, external draw.io) and the shell's side (one answer per request, after draw.io is up, never during a projection); the wiring test starts a session with BROWSER=none to see the no-tab message. Shell e2e: cells selected in the editor reach get_selection; a PNG of another page differs from the page on screen, which stays.
The server asks the preview tab for the selection the way it asks for an export (a random request id in GET /api/state, the answer in a POST with that id, 10 s to answer). The shell answers through the editor bridge with each cell's id, label, an edge's ends, a shape's geometry and the page on screen; without a same-origin editor it says so, and the tool names the external draw.io. The classic page cannot answer, so the tool says that at once. screenshot_diagram's description now says a page selector renders that page without changing the page on screen (PNG exports by pageId already did).
In a session of its own: three writes give three cards; undoing the newest
restores the one before on the server too, redo brings it back, a hand edit
turns the undo into a restore, and restoring the first version keeps that
edit as a version of its own, which restore_version also finds.
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.
Each History entry records who made it (a user edit, a recovering tab's
copy, a restored copy; none for the AI's writes), when, and its page
count. GET /api/history now also returns each entry's XML, the first entry
with the same content (a restore adds a copy of an older one), the state
the ids belong to, and the entry whose content the canvas shows, by the
rule restore_version uses. The shell's version cards read these; the
classic page keeps using index, id and svg.
A write taken in place that leaves the canvas as it is gets no autosave from draw.io, so the marker for its copy stayed armed and ate the user's next paper-size edit: arm it only when the write changed the document. The 15 s export timeout now retires the export's sequence number, so a result POST that answers late no longer restores the document a second time.
An autosave that arrives after loadDiagram sent a full load, and before draw.io reports it, is of the canvas being replaced (draw.io reports each load, in order). Until now it overwrote chartXMLRef: in the MCP shell, a late autosave of a one-page projection replaced the cached document, and a remount of an external draw.io then put the projection on the canvas as the whole document.
The e2e job's first shard builds the MCP package, packs it, installs the
tarball in an empty directory and runs packages/mcp-server/tests/e2e
against the installed dist/index.js (MCP_SERVER_ENTRY), so a shell that
builds but fails in the browser, or a tarball missing a runtime
dependency, fails the PR. Its traces go with the Playwright report. The
publish workflow also triggers on the web app code the shell is bundled
from (components, contexts, hooks, lib, stores, globals.css) and the
root lockfile.
tsc -p shell checked nothing: the inherited exclude dropped every shell
file; the shell's tsconfig now excludes node_modules only. Tailwind scans
app-toaster.tsx too, so the sync notices look like the web app's toasts.
The bundle keeps its dependencies' license comments (esbuild appends them
at the end). postcss, which build-shell.mjs loads from the root, is a
declared devDependency.
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.
A recovery loads the server's diagram in full and waits for draw.io's
load report, as the classic page does: whether the canvas takes a write
in place is decided inside DiagramProvider, and an autosave of the
canvas being replaced went to the server as an edit when the decision
was wrong. A paper size change alone is pushed again: autosaves are
compared as documents only for draw.io's own copy of a committed write.
A projection stays on screen until draw.io reports the restore load
(5 s at most), the whole export ends in 15 s even when its result POST
hangs, and an export in flight is dropped when draw.io starts over. A
refused poll shows the tab offline. With several pages and the page on
screen unknown, a write loads in full. hasLoadOnlySettings and the
highlight of an AI change are shared with the editor bridge.
The shell connects, shows what create_new_diagram draws, marks an
edit_diagram change and takes it back with one Ctrl+Z (which get_diagram
then reflects), pushes a shape inserted in the editor, serves
screenshot_diagram, and shows another page only for its SVG export before
the user's page comes back.
The recovery, thumbnail, size limit and History cases of
tests/unit/mcp-preview-recovery.test.ts, driven against mcp-sync-core.ts
with a stubbed server and canvas, plus the stale 409 recovery, an export
request answered once, a projection that ignores edits and restores the
document, the thumbnail of a write loaded before draw.io was ready, writes
taken in place as commits (draw.io's own copy is not pushed), and the
commit-or-load decision table of decideLoad.
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.
requestExport(request, timeoutMs) runs one draw.io export with the
request's own parameters (a PNG's pageId and width) and resolves with its
answer (data, or xml for format "xml"); null when draw.io does not answer.
showTransient(xml) puts a document on the canvas for an export only: it is
not recorded, its autosaves are ignored, and the next loadDiagram brings
the user back to the page they were on. The MCP's canvas shell answers the
server's export requests with both.
npm run test:e2e starts dist/index.js over the MCP SDK with
DRAWIO_PREVIEW_UI=shell, opens the URL start_session returns in headless
Chromium, and checks that the bundled draw.io loads without console
errors and that the theme toggle switches draw.io in place.
GET /shell/ fills the page template's {{CONFIG_JSON}} with the session,
the API token, where draw.io comes from and the host's editor settings,
with the classic page's security headers; /shell/<file> serves the built
files like the draw.io copy. start_session opens the shell when
DRAWIO_PREVIEW_UI=shell; the classic page stays the default.
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.
- Mermaid's converter is in js/extensions.min.js, which the editor loads at
startup, so the README no longer lists it as left out; the org chart
layout (js/orgchart.min.js) is the example of a feature that is.
- Note that the bundled copy, like the web app's, has no /drawio/proxy:
images from other websites, including those in some templates, are left
out of exports and thumbnails. The guard's comment names this as a known
limitation it does not cover.
- Export requests carried a per-process counter. The preview page retries a
result refused with 403 against the process that took over the port, so a
late result of the old process's export could be taken for the new
process's export with the same number. The id is a random UUID now.
- The ETag of a bundled draw.io file now starts with the version the fetch
script stamps into dist/drawio/.version. An install that keeps the
archive's dates (npm does not) would otherwise answer 304 for a changed
file of the same size after an upgrade.
- busyReason had no reader: the chat engine sets isBusy through the store's
generic set, like every other flag.
- The isSameDocument comment says the two "same document" rules disagree
in both directions, so neither is a subset of the other.
- The import boundary test bundles minified with one pako (the MCP core
resolves its own copy) and caps the canvas core at 160 KB (134 KB now).
- The offline deployment guides point at packages/mcp-server/src/
drawio-version.json for the draw.war version; scripts/fetch-drawio.mjs
no longer names it.
- The MCP README says what the bundled draw.io copy includes, and that the
preview page cannot be shown inside an editor's built-in browser since it
is served with frame-ancestors 'self'.
- The list now ships the templates of Insert > Template, the PlantUML
parser of Insert > Advanced and the template dialog's icon: the menu
items were shown but failed with 404s. 15.1 MB packed; the tarball cap
goes from 40 MB to 20 MB, where it still catches a list that grew by a
whole js/ directory.
- The guard drives both features, fails when the copy it runs against
lacks files the editor asked for or when an export does not answer,
checks that the copy is the pinned draw.io version, and runs in CI
(npm run check-drawio, one E2E shard) so a list regression cannot reach
a release.
- The preview page fetches a fresh copy of itself and retries once when an
API request is refused with 403: another MCP process, with its own token,
now answers on this port, and the recovery logic (recoverState) needs its
polls to go through. The page is sent with Cache-Control: no-store.
- draw.io files are served with an ETag and Cache-Control: no-cache instead
of a 24 hour max-age: their names do not change between versions, so a
package upgrade must reach the browser on the next preview. HEAD and
If-None-Match (304) are answered.
- The file read stream goes through stream.pipeline, so a read error no
longer ends the MCP process and a client that leaves mid-download no
longer leaks the file handle.
GET /drawio/<path> serves dist/drawio with a MIME table, a day of
caching and nosniff; paths are normalized and never reach WEB-INF or
META-INF. The preview embeds /drawio/index.html when the copy exists and
DRAWIO_BASE_URL is unset, else the external draw.io as before (and
start_session says so). Every /api request must carry the per-process
X-Drawio-Token the page gets in its HTML; pages send
frame-ancestors 'self' and nosniff.
scripts/fetch-drawio.mjs downloads the pinned draw.war into a cache
(DRAWIO_WAR_CACHE, or DRAWIO_WAR for a local file), checks its SHA-256
and extracts the files named in drawio-files.txt plus a LICENSE with the
Apache-2.0 text. scripts/check-drawio-files.mjs drives the embedded
editor in headless Chromium from a full copy, records every requested
file and checks or rewrites (--update) the list.
The boundary test scans the canvas modules' imports and bundles the canvas components with esbuild; both fail on anything from components/chat, the tool handlers, next/navigation, next/font, next/script, next/headers or a server-only module. The card test renders VersionCard and VersionStrip on a fake VersionsSource.
The canvas components will be reused by the MCP server's browser shell,
which has no chat and no Next.js. They now read everything they need
from small contexts and the canvas store instead of the chat engine:
- components/canvas/versions-context.tsx: VersionsProvider and
useVersionsContext give the version cards, the strip and the compare
dialog a VersionsSource (versions, onCanvasId, undoneId, isBusy,
canUndo, canRedo, restore, undo, redo). The chat fills it from the
versions store and the engine in components/chat/chat-versions.tsx.
- stores/canvas-store.ts: isBusy and busyReason; the chat engine sets
them while a turn runs, SelectionAsk and the version UI read them.
- components/canvas/version-card.tsx: the visual version card and the
thumbnail, out of tool-activity.tsx; the chat's card composes it and
adds its "Show XML" link and code panel.
- compare-dialog.tsx and version-strip.tsx move to components/canvas;
the strip takes the minimum number of versions to show as a prop, the
chat panel computes it from the cards it has.
- components/canvas/locale-context.tsx: LocaleProvider and useLocale,
fed by the [lang] layout; CanvasStage no longer uses next/navigation.
The overlay (SelectionAsk) is a slot and the wait for the saved
language is a prop, so the shell can leave both out.
- lib/version-text.ts: describeChanges is now describeChangeSummary, so
it can be imported next to the MCP core's describeChanges.
* feat(mcp-server): optional screenshot attached to create_new_diagram and edit_diagram results
Both write tools take an optional boolean `screenshot`; the default comes
from DRAWIO_AUTO_SCREENSHOT. The body of screenshot_diagram moved into
captureScreenshot so the write tools can append the PNG and checklist to
their result, or a "Screenshot skipped" note when the preview tab is not
available. The preview page delays the PNG export by 600 ms right after
loading a new version so icon images finish loading.
* fix(mcp-server): review fixes for screenshot attached to create and edit results
* fix(mcp-server): Codex review fixes for the screenshot on write results
- A cleared canvas also gets the screenshot note when one was asked for
- The note for a tab that never polled says it may not have connected yet
* docs: list undo and custom drawing rules among the MCP features
* test(mcp-server): truncation check with named styles and compact cells after the merge
dayuan.jiang