fix(trash): implement robust ancestor-preserving restore and filterActiveTree for trash reliability

src/components/layout/AppShell.tsx

@@ -20,6 +20,7 @@ import {
   findTaskInTree,
   getAllTrashTasks,
   filterTasksByTag,
+  filterActiveTree,
 } from "@/lib/mockData";
 
 interface AppShellProps {
@@ -126,10 +127,10 @@ export function AppShell({ user, isDemo = false }: AppShellProps) {
       } else if (selectedTag) {
         setTasks(filterTasksByTag(store.tasks, selectedTag) as Task[]);
       } else if (selectedListId) {
-        const listTasks = (store.tasks as Task[]).filter(
-          (t) => !t.isDeleted && t.listId === selectedListId && (showCompleted ? true : !t.completed)
+        const listTasks = filterActiveTree(store.tasks as MockTask[], showCompleted).filter(
+          (t) => t.listId === selectedListId
         );
-        setTasks(listTasks);
+        setTasks(listTasks as Task[]);
       } else {
         setTasks([]);
       }
@@ -337,7 +338,13 @@ export function AppShell({ user, isDemo = false }: AppShellProps) {
       const store = getDemoStore();
       const newTasks = moveToTrashInTree(store.tasks, task.id);
       saveDemoStore(store.lists, newTasks);
-      setTasks((prev) => prev.filter((t) => t.id !== task.id));
+      if (isTrashActive) {
+        setTasks(getAllTrashTasks(newTasks) as Task[]);
+      } else if (selectedListId) {
+        setTasks(filterActiveTree(newTasks, showCompleted).filter((t) => t.listId === selectedListId) as Task[]);
+      } else if (selectedTag) {
+        setTasks(filterTasksByTag(newTasks, selectedTag) as Task[]);
+      }
       if (selectedTask?.id === task.id) setSelectedTask(null);
     } else {
       setTasks((prev) => prev.filter((t) => t.id !== task.id));

src/components/layout/Sidebar.tsx

@@ -7,7 +7,7 @@ import { useTheme } from "@/app/providers";
 import { LanguageSelector } from "@/components/ui/LanguageSelector";
 import { ContextMenu, MenuItem } from "@/components/ui/ContextMenu";
 import { SettingsModal } from "@/components/settings/SettingsModal";
-import { getCustomTags, MockTag, getAllTrashTasks, getDemoStore, getTagTaskCount } from "@/lib/mockData";
+import { getCustomTags, MockTag, getAllTrashTasks, getDemoStore, getTagTaskCount, filterActiveTree, MockTask } from "@/lib/mockData";
 
 interface User { id: string; name?: string | null; email?: string | null }
 interface List { id: string; name: string; color: string; icon: string; _count?: { tasks: number } }
@@ -578,8 +578,8 @@ export function Sidebar({
                   ? (() => {
                       if (typeof window === "undefined") return "";
                       const store = getDemoStore();
-                      const cnt = store.tasks.filter((t) => t.listId === list.id && !t.isDeleted && !t.completed).length;
-                      return cnt > 0 ? cnt : "";
+                      const active = filterActiveTree(store.tasks as MockTask[], false).filter((t) => t.listId === list.id);
+                      return active.length > 0 ? active.length : "";
                     })()
                   : list._count?.tasks || ""}
               </span>
@@ -646,7 +646,7 @@ export function Sidebar({
                 ? getAllTrashTasks(getDemoStore().tasks).length
                 : (externalTrashCount !== undefined ? externalTrashCount : internalTrashCount);
               return count > 0 ? (
-                <span className="item-count" style={{ color: "var(--danger)", fontWeight: 600 }}>{count}</span>
+                <span className="item-count" style={{ color: "var(--danger)", fontWeight: 700 }}>{count}</span>
               ) : null;
             })()}
           </div>

src/lib/mockData.ts

@@ -278,24 +278,56 @@ export function moveToTrashInTree(tree: MockTask[], id: string): MockTask[] {
   });
 }
 
-// Restore from Trash (recursively unmark node and its children)
-export function restoreTaskInTree(tree: MockTask[], id: string): MockTask[] {
-  const markRestored = (node: MockTask): MockTask => ({
+// Restore task (and all its subtasks) from Trash, ensuring ancestor parents are also un-deleted
+export function restoreTaskInTree(tree: MockTask[], targetId: string): MockTask[] {
+  const unmarkNodeAndChildren = (node: MockTask): MockTask => ({
     ...node,
     isDeleted: false,
     deletedAt: null,
-    children: node.children ? node.children.map(markRestored) : [],
+    children: node.children ? node.children.map(unmarkNodeAndChildren) : [],
   });
 
-  return tree.map((node) => {
-    if (node.id === id) {
-      return markRestored(node);
+  function processNodes(nodes: MockTask[]): { updated: MockTask[]; found: boolean } {
+    let foundInThisLevel = false;
+    const updated = nodes.map((node) => {
+      if (node.id === targetId) {
+        foundInThisLevel = true;
+        return unmarkNodeAndChildren(node);
+      }
+      if (node.children && node.children.length > 0) {
+        const res = processNodes(node.children);
+        if (res.found) {
+          foundInThisLevel = true;
+          // If a child was restored, ancestor parent must also be restored
+          return {
+            ...node,
+            isDeleted: false,
+            deletedAt: null,
+            children: res.updated,
+          };
+        }
+        return { ...node, children: res.updated };
+      }
+      return node;
+    });
+    return { updated, found: foundInThisLevel };
+  }
+
+  return processNodes(tree).updated;
+}
+
+// Recursively filter active tree (stripping isDeleted tasks at all depths)
+export function filterActiveTree(nodes: MockTask[], showCompleted = true): MockTask[] {
+  const result: MockTask[] = [];
+  for (const node of nodes) {
+    if (!node.isDeleted) {
+      if (showCompleted || !node.completed) {
+        const cleanChildren = node.children ? filterActiveTree(node.children, showCompleted) : [];
+        result.push({ ...node, children: cleanChildren });
+      }
     }
-    if (node.children && node.children.length > 0) {
-      return { ...node, children: restoreTaskInTree(node.children, id) };
-    }
-    return node;
-  });
+  }
+  return result;
 }
 
 // Permanent delete