[arribada] feat(gantt): undo / Ctrl+Z for bar date edits

Record an issue's dates before each bar drag/resize; an Undo button (and Ctrl/Cmd+Z,
ignored while typing) re-applies the previous dates via updateIssue. Stack is
per-project (cleared on project change), capped at 50.

Author: Schade77

apps/web/ce/components/gantt-chart/undo-button.tsx

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) 2026-present Arribada Initiative and contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ * See the LICENSE file for details.
+ *
+ * Small Undo control for the issue gantt — appears only when a bar date edit can
+ * be reverted. Ctrl+Z does the same thing (wired in base-gantt-root).
+ */
+import { observer } from "mobx-react";
+import { Undo2 } from "lucide-react";
+import { ganttUndo } from "@/plane-web/store/gantt-undo";
+
+export const GanttUndoButton = observer(function GanttUndoButton({ onUndo }: { onUndo: () => void }) {
+  if (!ganttUndo.canUndo) return null;
+  return (
+    <button
+      type="button"
+      onClick={onUndo}
+      title="Undo last date change (Ctrl+Z)"
+      className="flex items-center gap-1.5 rounded-md border border-subtle bg-layer-1 px-2 py-1 text-12 text-secondary shadow-sm hover:bg-layer-2"
+    >
+      <Undo2 className="size-3.5" />
+      Undo
+    </button>
+  );
+});

apps/web/ce/store/gantt-undo.ts

@@ -0,0 +1,49 @@
+/**
+ * Copyright (c) 2026-present Arribada Initiative and contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ * See the LICENSE file for details.
+ *
+ * A tiny undo stack for gantt bar date edits. The bar drag/resize handler records
+ * each issue's dates BEFORE the change; Ctrl+Z (or the Undo button) re-applies the
+ * previous dates. Cleared when the project changes so undo never crosses projects.
+ */
+import { action, computed, makeObservable, observable } from "mobx";
+
+export type GanttUndoEntry = {
+  projectId: string | null | undefined;
+  issueId: string;
+  prev: { start_date?: string | null; target_date?: string | null };
+};
+
+class GanttUndoStore {
+  stack: GanttUndoEntry[] = [];
+
+  constructor() {
+    makeObservable(this, {
+      stack: observable.shallow,
+      canUndo: computed,
+      push: action,
+      pop: action,
+      clear: action,
+    });
+  }
+
+  get canUndo(): boolean {
+    return this.stack.length > 0;
+  }
+
+  push(entry: GanttUndoEntry): void {
+    this.stack.push(entry);
+    if (this.stack.length > 50) this.stack.shift();
+  }
+
+  pop(): GanttUndoEntry | undefined {
+    return this.stack.pop();
+  }
+
+  clear(): void {
+    this.stack = [];
+  }
+}
+
+export const ganttUndo = new GanttUndoStore();

apps/web/core/components/issues/issue-layouts/gantt/base-gantt-root.tsx

@@ -18,6 +18,8 @@ import { renderFormattedPayloadDate } from "@plane/utils";
 import { TimeLineTypeContext } from "@/components/gantt-chart/contexts";
 import { GanttChartRoot } from "@/components/gantt-chart/root";
 import { GanttColorBy } from "@/plane-web/components/gantt-chart/color-by";
+import { GanttUndoButton } from "@/plane-web/components/gantt-chart/undo-button";
+import { ganttUndo } from "@/plane-web/store/gantt-undo";
 import { IssueGanttSidebar } from "@/components/gantt-chart/sidebar/issues/sidebar";
 // hooks
 import { useIssues } from "@/hooks/store/use-issues";
@@ -85,12 +87,48 @@ export const BaseGanttRoot = observer(function BaseGanttRoot(props: IBaseGanttRo
   const updateIssueBlockStructure = async (issue: TIssue, data: IBlockUpdateData) => {
     if (!workspaceSlug) return;
 
+    // record the pre-change dates so Ctrl+Z / Undo can revert a bar drag or resize
+    if (data.start_date !== undefined || data.target_date !== undefined) {
+      ganttUndo.push({
+        projectId: issue.project_id,
+        issueId: issue.id,
+        prev: { start_date: issue.start_date, target_date: issue.target_date },
+      });
+    }
+
     const payload: any = { ...data };
     if (data.sort_order) payload.sort_order = data.sort_order.newSortOrder;
 
     updateIssue && (await updateIssue(issue.project_id, issue.id, payload));
   };
 
+  // revert the last recorded bar date edit
+  const handleGanttUndo = useCallback(async () => {
+    const entry = ganttUndo.pop();
+    if (!entry || !updateIssue) return;
+    await updateIssue(entry.projectId, entry.issueId, entry.prev);
+  }, [updateIssue]);
+
+  // Ctrl/Cmd+Z reverts the last bar date edit (ignored while typing in a field)
+  useEffect(() => {
+    const onKey = (e: KeyboardEvent) => {
+      if (!((e.ctrlKey || e.metaKey) && !e.shiftKey && e.key.toLowerCase() === "z")) return;
+      const el = document.activeElement as HTMLElement | null;
+      if (el?.tagName === "INPUT" || el?.tagName === "TEXTAREA" || el?.isContentEditable) return;
+      if (!ganttUndo.canUndo) return;
+      e.preventDefault();
+      void handleGanttUndo();
+    };
+    window.addEventListener("keydown", onKey);
+    return () => window.removeEventListener("keydown", onKey);
+  }, [handleGanttUndo]);
+
+  // undo history is scoped to the current project
+  useEffect(() => {
+    ganttUndo.clear();
+    return () => ganttUndo.clear();
+  }, [projectId]);
+
   const isAllowed = allowPermissions([EUserPermissions.ADMIN, EUserPermissions.MEMBER], EUserPermissionsLevel.PROJECT);
   const updateBlockDates = useCallback(
     (
@@ -129,8 +167,9 @@ export const BaseGanttRoot = observer(function BaseGanttRoot(props: IBaseGanttRo
     <IssueLayoutHOC layout={EIssueLayoutTypes.GANTT}>
       <TimeLineTypeContext.Provider value={GANTT_TIMELINE_TYPE.ISSUE}>
         <div className="relative h-full w-full">
-          <div className="absolute left-3 top-1.5 z-20">
+          <div className="absolute left-3 top-1.5 z-20 flex items-center gap-2">
             <GanttColorBy />
+            <GanttUndoButton onUndo={handleGanttUndo} />
           </div>
           <GanttChartRoot
             border={false}