test(FN-4316): complete Step 4 — add todo aging column coverage

Fusion-Task-Id: FN-4316
Fusion-Task-Lineage: 6b2b78b4-effa-479c-9a22-5a53d0f74894

packages/dashboard/app/components/__tests__/Column.test.tsx

@@ -438,7 +438,7 @@ describe("Column same-column drop", () => {
     
     render(<Column {...defaultProps} column="todo" tasks={tasks} onMoveTask={onMoveTask} addToast={addToast} />);
 
-    const columnEl = screen.getByText("1").closest(".column") as HTMLElement;
+    const columnEl = screen.getByRole("heading", { name: "Todo" }).closest(".column") as HTMLElement;
     const dataTransfer = {
       getData: vi.fn().mockReturnValue("FN-001"),
       dropEffect: "move",
@@ -456,7 +456,7 @@ describe("Column same-column drop", () => {
     
     render(<Column {...defaultProps} column="todo" tasks={tasks} onMoveTask={onMoveTask} />);
 
-    const columnEl = screen.getByText("1").closest(".column") as HTMLElement;
+    const columnEl = screen.getByRole("heading", { name: "Todo" }).closest(".column") as HTMLElement;
     const dataTransfer = {
       getData: vi.fn().mockReturnValue("FN-001"),
       dropEffect: "move",
@@ -536,6 +536,90 @@ describe("Column same-column drop", () => {
   });
 });
 
+describe("Column todo aging summary", () => {
+  const now = new Date("2026-04-04T12:00:00Z").getTime();
+
+  const makeTodoTask = (id: string, ageDays: number): Task => ({
+    ...makeTask(id),
+    column: "todo",
+    columnMovedAt: new Date(now - ageDays * 24 * 60 * 60 * 1000).toISOString(),
+    createdAt: new Date(now - ageDays * 24 * 60 * 60 * 1000).toISOString(),
+    updatedAt: new Date(now - ageDays * 24 * 60 * 60 * 1000).toISOString(),
+  });
+
+  it.each(["triage", "in-progress", "in-review", "done", "archived"] as const)(
+    "renders aging summary only on todo column (not %s)",
+    (column) => {
+      render(<Column {...defaultProps} column={column} tasks={[{ ...makeTask("FN-001"), column }]} lastFetchTimeMs={now} />);
+      expect(screen.queryByTestId("todo-aging-summary")).toBeNull();
+    },
+  );
+
+  it("renders aging summary counts for todo bucket totals", () => {
+    render(
+      <Column
+        {...defaultProps}
+        column="todo"
+        tasks={[makeTodoTask("FN-001", 2), makeTodoTask("FN-002", 10), makeTodoTask("FN-003", 45)]}
+        lastFetchTimeMs={now}
+      />,
+    );
+
+    expect(screen.getByTestId("todo-aging-chip-fresh")).toHaveTextContent("0–7d1");
+    expect(screen.getByTestId("todo-aging-chip-aging")).toHaveTextContent("8–30d1");
+    expect(screen.getByTestId("todo-aging-chip-stale")).toHaveTextContent("31+d1");
+  });
+
+  it("filters todo tasks by selected bucket and toggles off on second click", async () => {
+    const user = userEvent.setup();
+    render(
+      <Column
+        {...defaultProps}
+        column="todo"
+        tasks={[makeTodoTask("FN-001", 2), makeTodoTask("FN-002", 10), makeTodoTask("FN-003", 45)]}
+        lastFetchTimeMs={now}
+      />,
+    );
+
+    await user.click(screen.getByTestId("todo-aging-chip-stale"));
+    expect(screen.queryByTestId("task-FN-001")).toBeNull();
+    expect(screen.queryByTestId("task-FN-002")).toBeNull();
+    expect(screen.getByTestId("task-FN-003")).toBeTruthy();
+    const columnCount = screen.getByText((_content, node) => {
+      if (!node || !node.classList.contains("column-count")) {
+        return false;
+      }
+      return node.textContent?.includes("1 / 3") ?? false;
+    });
+    expect(columnCount).toBeTruthy();
+
+    await user.click(screen.getByTestId("todo-aging-chip-stale"));
+    expect(screen.getByTestId("task-FN-001")).toBeTruthy();
+    expect(screen.getByTestId("task-FN-002")).toBeTruthy();
+    expect(screen.getByTestId("task-FN-003")).toBeTruthy();
+  });
+
+  it("renders empty bucket hint and clear filter action when selected bucket has no tasks", async () => {
+    const user = userEvent.setup();
+    render(
+      <Column
+        {...defaultProps}
+        column="todo"
+        tasks={[makeTodoTask("FN-001", 2), makeTodoTask("FN-002", 8)]}
+        lastFetchTimeMs={now}
+      />,
+    );
+
+    await user.click(screen.getByTestId("todo-aging-chip-stale"));
+    expect(screen.getByText("No tasks in this bucket")).toBeTruthy();
+
+    await user.click(screen.getByRole("button", { name: "Clear filter" }));
+    expect(screen.queryByText("No tasks in this bucket")).toBeNull();
+    expect(screen.getByTestId("task-FN-001")).toBeTruthy();
+    expect(screen.getByTestId("task-FN-002")).toBeTruthy();
+  });
+});
+
 describe("Column PluginSlot integration", () => {
   it("renders PluginSlot for board-column-footer", () => {
     mockUsePluginUiSlots.mockReturnValue({