Dashboard editor undo: ⌘Z / ⇧⌘Z over a 50-entry history of commits, folding keystrokes and the grid's own correction as the flow editor does

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WgBfkm4rCmtd1T4vHWjEPx

frontend/src/components/Dashboard/DashboardEditor.tsx

@@ -288,6 +288,41 @@ const scaledStrategy = (scale: number) => ({
   calcStyle: setTransform as (pos: Position) => CSSProperties,
 })
 
+/** Dashboards to step back and forward through, newest last. */
+type History = {
+  past: Dashboard[]
+  future: Dashboard[]
+  /** When the last entry was recorded, so a burst of typing stays one edit. */
+  at: number
+}
+
+const HISTORY_LIMIT = 50
+const TYPING_WINDOW = 500
+
+/**
+ * Remember the dashboard as it was before a change.
+ *
+ * Fields commit on every keystroke, and the grid writes back its own
+ * correction a moment after a widget comes or goes, so consecutive edits that
+ * leave the same widgets in place fold into the entry already on the stack.
+ * Adding, removing or reordering a widget is a finished action and starts its
+ * own.
+ */
+function record(history: History, previous: Dashboard, next: Dashboard) {
+  const before = widgetsOf(previous)
+  const after = widgetsOf(next)
+  const sameWidgets =
+    before.length === after.length &&
+    before.every((widget, index) => widget.id === after[index].id)
+  if (!sameWidgets || Date.now() - history.at >= TYPING_WINDOW) {
+    history.past.push(previous)
+    if (history.past.length > HISTORY_LIMIT) history.past.shift()
+  }
+  history.at = Date.now()
+  // A new change is a new branch: what was undone is not coming back.
+  history.future = []
+}
+
 const same = (a: Layout, b: Layout) =>
   a.length === b.length &&
   a.every((item, index) => {
@@ -349,6 +384,7 @@ export function DashboardEditor({
   // The saved version is what the next save is based on; without following it
   // the second save of a session is always a conflict.
   const version = useRef(dashboard.version)
+  const history = useRef<History>({ past: [], future: [], at: 0 })
 
   useEffect(() => {
     version.current = dashboard.version
@@ -369,7 +405,8 @@ export function DashboardEditor({
     return request
   }
 
-  const commit = (next: Dashboard) => {
+  /** Put a dashboard on the canvas and on its way to the server. */
+  const apply = (next: Dashboard) => {
     setDraft(next)
     if (timer.current) clearTimeout(timer.current)
     timer.current = setTimeout(() => {
@@ -378,6 +415,25 @@ export function DashboardEditor({
     }, AUTOSAVE_MS)
   }
 
+  /** Apply a change and make it undoable. */
+  const commit = (next: Dashboard) => {
+    record(history.current, draft, next)
+    apply(next)
+  }
+
+  /**
+   * Step through the history. Undo and redo save like any other edit, so the
+   * autosave debounce collapses a run of them into one write.
+   */
+  const step = (back: boolean) => {
+    const { past, future } = history.current
+    const remembered = (back ? past : future).pop()
+    if (!remembered) return
+    ;(back ? future : past).push(draft)
+    history.current.at = 0
+    apply(remembered)
+  }
+
   /** Send what is queued and wait for the server to have it. */
   const flush = async () => {
     if (timer.current) {
@@ -439,10 +495,13 @@ export function DashboardEditor({
     setSettingsOpen(true)
   }
 
-  // As on the flow canvas, and reachable while typing for the same reasons.
-  // Outside edit mode both keys stay the browser's.
+  // As on the flow canvas: undo and redo step aside while typing, since a
+  // field keeps its own, and ⌘P and ⌘S stay reachable for the same reasons.
+  // Outside edit mode every key stays the browser's.
   useShortcuts(
     {
+      "mod+z": () => (edit ? step(true) : false),
+      "mod+shift+z": () => (edit ? step(false) : false),
       "mod+p": () => (edit ? setPaletteOpen((open) => !open) : false),
       // An edit still waiting for its autosave counts: publishing flushes it.
       "mod+s": () => {