diff --git a/ui/src/lib/inbox.test.ts b/ui/src/lib/inbox.test.ts
index 76deef856b..3fdf2ef02a 100644
--- a/ui/src/lib/inbox.test.ts
+++ b/ui/src/lib/inbox.test.ts
@@ -35,6 +35,7 @@ import {
   loadInboxIssueColumns,
   loadInboxWorkItemGroupBy,
   loadCollapsedInboxGroupKeys,
+  loadCollapsedInboxParentIds,
   loadLastInboxTab,
   matchesInboxIssueSearch,
   normalizeInboxIssueColumns,
@@ -45,6 +46,7 @@ import {
   resolveInboxSelectionIndex,
   saveInboxFilterPreferences,
   saveCollapsedInboxGroupKeys,
+  saveCollapsedInboxParentIds,
   saveInboxIssueColumns,
   saveInboxWorkItemGroupBy,
   saveLastInboxTab,
@@ -1560,6 +1562,23 @@ describe("inbox helpers", () => {
     expect(loadCollapsedInboxGroupKeys("company-1")).toEqual(new Set());
   });
 
+  it("persists collapsed inbox parents per company", () => {
+    saveCollapsedInboxParentIds("company-1", new Set(["parent-1", "parent-2"]));
+    saveCollapsedInboxParentIds("company-2", new Set(["parent-3"]));
+
+    expect(loadCollapsedInboxParentIds("company-1")).toEqual(new Set(["parent-1", "parent-2"]));
+    expect(loadCollapsedInboxParentIds("company-2")).toEqual(new Set(["parent-3"]));
+
+    saveCollapsedInboxParentIds("company-1", new Set());
+    expect(loadCollapsedInboxParentIds("company-1")).toEqual(new Set());
+  });
+
+  it("returns empty collapsed inbox parents for missing or invalid storage", () => {
+    expect(loadCollapsedInboxParentIds("company-1")).toEqual(new Set());
+    localStorage.setItem("paperclip:inbox:collapsed-parents:company-1", JSON.stringify({ nope: true }));
+    expect(loadCollapsedInboxParentIds("company-1")).toEqual(new Set());
+  });
+
   it("does not reset workspace grouping before experimental settings have loaded", () => {
     expect(shouldResetInboxWorkspaceGrouping("workspace", false, false)).toBe(false);
   });
diff --git a/ui/src/lib/inbox.ts b/ui/src/lib/inbox.ts
index be0e9145f7..284a1163a2 100644
--- a/ui/src/lib/inbox.ts
+++ b/ui/src/lib/inbox.ts
@@ -26,6 +26,7 @@ export const INBOX_NESTING_KEY = "paperclip:inbox:nesting";
 export const INBOX_GROUP_BY_KEY = "paperclip:inbox:group-by";
 export const INBOX_FILTER_PREFERENCES_KEY_PREFIX = "paperclip:inbox:filters";
 export const INBOX_COLLAPSED_GROUPS_KEY_PREFIX = "paperclip:inbox:collapsed-groups";
+export const INBOX_COLLAPSED_PARENTS_KEY_PREFIX = "paperclip:inbox:collapsed-parents";
 export type InboxTab = "mine" | "recent" | "unread" | "blocked" | "all";
 export type InboxCategoryFilter =
   | "everything"
@@ -187,6 +188,11 @@ function getInboxCollapsedGroupsStorageKey(companyId: string | null | undefined)
   return `${INBOX_COLLAPSED_GROUPS_KEY_PREFIX}:${companyId}`;
 }
 
+function getInboxCollapsedParentsStorageKey(companyId: string | null | undefined): string | null {
+  if (!companyId) return null;
+  return `${INBOX_COLLAPSED_PARENTS_KEY_PREFIX}:${companyId}`;
+}
+
 export function loadInboxFilterPreferences(
   companyId: string | null | undefined,
 ): InboxFilterPreferences {
@@ -271,6 +277,36 @@ export function saveCollapsedInboxGroupKeys(
   }
 }
 
+export function loadCollapsedInboxParentIds(
+  companyId: string | null | undefined,
+): Set<string> {
+  const storageKey = getInboxCollapsedParentsStorageKey(companyId);
+  if (!storageKey) return new Set();
+
+  try {
+    const raw = localStorage.getItem(storageKey);
+    if (!raw) return new Set();
+    const parsed = JSON.parse(raw);
+    return new Set(Array.isArray(parsed) ? parsed.filter((entry): entry is string => typeof entry === "string") : []);
+  } catch {
+    return new Set();
+  }
+}
+
+export function saveCollapsedInboxParentIds(
+  companyId: string | null | undefined,
+  parentIds: ReadonlySet<string>,
+) {
+  const storageKey = getInboxCollapsedParentsStorageKey(companyId);
+  if (!storageKey) return;
+
+  try {
+    localStorage.setItem(storageKey, JSON.stringify([...parentIds]));
+  } catch {
+    // Ignore localStorage failures.
+  }
+}
+
 export function loadDismissedInboxAlerts(): Set<string> {
   try {
     const raw = localStorage.getItem(DISMISSED_KEY);
diff --git a/ui/src/pages/Inbox.test.tsx b/ui/src/pages/Inbox.test.tsx
index 2879a6841d..4e5cb53bb5 100644
--- a/ui/src/pages/Inbox.test.tsx
+++ b/ui/src/pages/Inbox.test.tsx
@@ -345,6 +345,80 @@ describe("Inbox toolbar", () => {
     act(() => root.unmount());
   });
 
+  it("restores folded and unfolded sub-tasks across remounts", async () => {
+    routerMock.location.pathname = "/inbox/mine";
+    const storageKey = "paperclip:inbox:collapsed-parents:company-1";
+    localStorage.removeItem(storageKey);
+
+    const parent = createIssue({
+      id: "parent-issue",
+      identifier: "PAP-1001",
+      title: "Parent inbox task",
+    });
+    const child = createIssue({
+      id: "child-issue",
+      identifier: "PAP-1002",
+      parentId: parent.id,
+      title: "Nested inbox task",
+    });
+    apiMocks.issuesList.mockResolvedValue([parent, child]);
+
+    const mountInbox = async () => {
+      const queryClient = new QueryClient({
+        defaultOptions: { queries: { retry: false, staleTime: 0, gcTime: 0 } },
+      });
+      const root = createRoot(container);
+      await act(async () => {
+        root.render(
+          <QueryClientProvider client={queryClient}>
+            <Inbox />
+          </QueryClientProvider>,
+        );
+      });
+      await vi.waitFor(() => {
+        expect(container.textContent).toContain(parent.title);
+      });
+      return root;
+    };
+    const parentToggle = () => {
+      const parentRow = Array.from(container.querySelectorAll("[data-inbox-item]"))
+        .find((row) => row.textContent?.includes(parent.title));
+      return parentRow?.querySelector<HTMLButtonElement>('button[data-slot="icon-button"]') ?? null;
+    };
+
+    let root = await mountInbox();
+    try {
+      expect(container.textContent).toContain(child.title);
+
+      await act(async () => {
+        parentToggle()?.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+      });
+      await vi.waitFor(() => {
+        expect(container.textContent).not.toContain(child.title);
+      });
+      expect(JSON.parse(localStorage.getItem(storageKey) ?? "[]")).toEqual([parent.id]);
+
+      act(() => root.unmount());
+      root = await mountInbox();
+      expect(container.textContent).not.toContain(child.title);
+
+      await act(async () => {
+        parentToggle()?.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+      });
+      await vi.waitFor(() => {
+        expect(container.textContent).toContain(child.title);
+      });
+      expect(JSON.parse(localStorage.getItem(storageKey) ?? "[]")).toEqual([]);
+
+      act(() => root.unmount());
+      root = await mountInbox();
+      expect(container.textContent).toContain(child.title);
+    } finally {
+      localStorage.removeItem(storageKey);
+      act(() => root.unmount());
+    }
+  });
+
   it("shows blocked toolbar controls on the Blocked tab", async () => {
     routerMock.location.pathname = "/inbox/blocked";
     const queryClient = new QueryClient({
diff --git a/ui/src/pages/Inbox.tsx b/ui/src/pages/Inbox.tsx
index e9abc46966..4bf93eb0d4 100644
--- a/ui/src/pages/Inbox.tsx
+++ b/ui/src/pages/Inbox.tsx
@@ -144,6 +144,7 @@ import {
   isInboxEntityDismissed,
   isMineInboxTab,
   loadCollapsedInboxGroupKeys,
+  loadCollapsedInboxParentIds,
   loadInboxFilterPreferences,
   loadInboxIssueColumns,
   loadInboxNesting,
@@ -155,6 +156,7 @@ import {
   resolveInboxSelectionIndex,
   saveInboxFilterPreferences,
   saveCollapsedInboxGroupKeys,
+  saveCollapsedInboxParentIds,
   saveInboxIssueColumns,
   saveInboxNesting,
   saveInboxWorkItemGroupBy,
@@ -801,6 +803,7 @@ export function Inbox() {
       previousSelectedCompanyIdRef.current = selectedCompanyId;
       setFilterPreferences(loadInboxFilterPreferences(selectedCompanyId));
       setCollapsedGroupKeys(loadCollapsedInboxGroupKeys(selectedCompanyId));
+      setCollapsedInboxParents(loadCollapsedInboxParentIds(selectedCompanyId));
     }
   }, [selectedCompanyId]);
 
@@ -1372,7 +1375,9 @@ export function Inbox() {
       return next;
     });
   }, []);
-  const [collapsedInboxParents, setCollapsedInboxParents] = useState<Set<string>>(new Set());
+  const [collapsedInboxParents, setCollapsedInboxParents] = useState<Set<string>>(
+    () => loadCollapsedInboxParentIds(selectedCompanyId),
+  );
   const [collapsedGroupKeys, setCollapsedGroupKeys] = useState<Set<string>>(() => loadCollapsedInboxGroupKeys(selectedCompanyId));
   const toggleGroupCollapse = useCallback((groupKey: string) => {
     setCollapsedGroupKeys((prev) => {
@@ -1508,18 +1513,20 @@ export function Inbox() {
       const next = new Set(prev);
       if (next.has(parentId)) next.delete(parentId);
       else next.add(parentId);
+      saveCollapsedInboxParentIds(selectedCompanyId, next);
       return next;
     });
-  }, []);
+  }, [selectedCompanyId]);
   const setInboxParentCollapsed = useCallback((parentId: string, collapsed: boolean) => {
     setCollapsedInboxParents((prev) => {
       if (prev.has(parentId) === collapsed) return prev;
       const next = new Set(prev);
       if (collapsed) next.add(parentId);
       else next.delete(parentId);
+      saveCollapsedInboxParentIds(selectedCompanyId, next);
       return next;
     });
-  }, []);
+  }, [selectedCompanyId]);
 
   // Build flat navigation list from visible rows so keyboard traversal respects collapsed groups.
   const flatNavItems = useMemo((): NavEntry[] => {