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
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.
* feat(mcp-server): list and resume saved diagram sessions
start_session accepts an optional session_id to continue a saved diagram
under the same preview URL and auto-save file, reporting the restored
pages. New read-only tool list_saved_diagrams prints every auto-saved
file newest first with its pages. Autosaver gains list() and dataDir().
INSTRUCTIONS and both READMEs mention the new tool.
* feat(mcp-server): add restore_version tool for undo and redo from History
Add the restore_version write tool so the model can put an earlier
version from History back on the canvas (steps_back, default 1). The
current canvas is kept in History unless it is the blank page, so a redo
is possible. http-server.ts exports restoreHistoryEntry, shared by the
HTTP restore endpoint and the tool; history.ts exports HistoryEntry and
otherVersions (distinct versions other than the canvas, newest first).
The drawing guide tells the model to call restore_version when the user
asks to undo, and both READMEs document the tool.
* feat(mcp-server): save the diagram History next to the auto-saved file
The Autosaver writes each session's History (the XML of its last 20 versions, without thumbnails) to <session-id>.history.json beside the .drawio file, after the same 1 second delay and only when the entries changed. When a saved session is resumed after an idle timeout or a process restart, the saved History is loaded back before the diagram, so the History panel and restore_version keep working. Removing the oldest files also removes their History files.
* fix(mcp-server): review fixes for saved sessions, undo tool, history on disk
* fix(mcp-server): Codex review fixes for saved sessions, undo and History on disk
- start_session resumes every saved file, also a cleared one or one of
empty named pages, and decompresses pages draw.io compressed
- History kept by a lost user edit or a recovering tab is saved too
- A diagram cleared before its first save keeps its History on disk
- The History file is written again after the 50-file cap removed it
- restore_version compares versions like the edit gate (a bare
mxGraphModel from the browser has no page name), checks the restore
result, and says "none" when no version is left
- The preview closes an open History list when the server state was
recreated, since the entries got new ids
- start_session's description mentions session_id
* fix(mcp-server): compare History versions pairwise and tie restores to the server state
Second Codex review of the History fixes:
- One bare mxGraphModel in History no longer hides page renames in every
comparison: names are left out only when one of the two is bare
- A History list asked for before the server recreated the session is
dropped, and a restore names the state its list belongs to; the server
refuses one from a lost state (History ids change after a restart)
* fix(mcp-server): restore from a History list with the state it was taken in
Third Codex review: a restore sent the tab's current state, so an old
list shown after a failed refresh passed the server's check. The list now
keeps the state it came from, and the server refuses a missing (null)
state too; only a tab of an older version, which sends none, is let
through.
dayuan.jiang