diff --git a/.changeset/fn-7377-planner-chat-failed-banner.md b/.changeset/fn-7377-planner-chat-failed-banner.md
new file mode 100644
index 0000000000..6d3dc3b88b
--- /dev/null
+++ b/.changeset/fn-7377-planner-chat-failed-banner.md
@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: Hide failed-task banners while task planner chat is maximized.
+category: fix
+dev: TaskDetailModal no longer mounts failed-banner chrome during expanded planner Chat; Activity and collapsed detail still show failures.
diff --git a/packages/dashboard/app/components/TaskDetailModal.tsx b/packages/dashboard/app/components/TaskDetailModal.tsx
index d97e058ad0..512919ce8b 100644
--- a/packages/dashboard/app/components/TaskDetailModal.tsx
+++ b/packages/dashboard/app/components/TaskDetailModal.tsx
@@ -2728,6 +2728,11 @@ export function TaskDetailContent({
   Maximized Activity applies to Live, Feed, and Raw Logs, not only the legacy `current` chat segment. Reserve the detail surface for header context and Activity content, and do not mount branch-group chrome in this mode so expand/promote controls are not hidden-but-focusable.
   */
   const shouldShowBranchGroupCard = Boolean(task.branchContext?.groupId && !isActivityExpanded);
+  /*
+  FNXC:TaskDetailPlannerChat 2026-07-01-00:00:
+  Maximized Planner Chat reserves vertical room for task identity and the planner conversation, so failed-task chrome is not mounted in that state. Normal detail, Activity expansion, and collapsed Planner Chat still surface task failures immediately.
+  */
+  const shouldShowTaskFailureAlert = Boolean(task.status === "failed" && task.error && !isPlannerChatExpanded);
 
   const taskActionMenuModel = useMemo(() => buildTaskActionMenuModel({
     task,
@@ -3463,7 +3468,7 @@ export function TaskDetailContent({
               {isWorkspaceTask(workingTask) && <WorkspaceWorktreesSummary task={workingTask} />}
             </>
           )}
-          {task.status === "failed" && task.error && (
+          {shouldShowTaskFailureAlert && (
             <div className="detail-error-alert">
               <span className="detail-error-icon">⚠</span>
               <div className="detail-error-content">
diff --git a/packages/dashboard/app/components/__tests__/TaskDetailModal.test.tsx b/packages/dashboard/app/components/__tests__/TaskDetailModal.test.tsx
index 1b92aeafe5..8dee9d1e02 100644
--- a/packages/dashboard/app/components/__tests__/TaskDetailModal.test.tsx
+++ b/packages/dashboard/app/components/__tests__/TaskDetailModal.test.tsx
@@ -228,6 +228,107 @@ describe("TaskDetailModal planner Chat tab", () => {
     expect(detail).toHaveClass("task-detail-content--planner-chat-expanded");
     expect(detail).not.toHaveClass("task-detail-content--chat-expanded");
   });
+
+  it("hides failed-task banner only while planner Chat is expanded and restores it on collapse", async () => {
+    const user = userEvent.setup();
+    const { container } = render(
+      <TaskDetailModal
+        initialTab="planner-chat"
+        taskDetailChatFirst
+        task={makeTask({ column: "todo" as any, status: "failed", error: "Planner failed hard" })}
+        onClose={noop}
+        onMoveTask={noopMove}
+        onDeleteTask={noopDelete}
+        onMergeTask={noopMerge}
+        onOpenDetail={noopOpenDetail}
+        addToast={noop}
+      />,
+    );
+    const detail = container.querySelector(".task-detail-content");
+
+    expect(screen.getByText("Task Failed")).toBeInTheDocument();
+    expect(screen.getByText("Planner failed hard")).toBeInTheDocument();
+    expect(container.querySelector(".detail-error-alert")).toBeInTheDocument();
+
+    await user.click(screen.getByTestId("task-planner-chat-expand-toggle"));
+
+    expect(detail).toHaveClass("task-detail-content--planner-chat-expanded");
+    expect(screen.queryByText("Task Failed")).not.toBeInTheDocument();
+    expect(screen.queryByText("Planner failed hard")).not.toBeInTheDocument();
+    expect(container.querySelector(".detail-error-alert")).toBeNull();
+
+    await user.click(screen.getByTestId("task-planner-chat-expand-toggle"));
+
+    expect(detail).not.toHaveClass("task-detail-content--planner-chat-expanded");
+    expect(screen.getByText("Task Failed")).toBeInTheDocument();
+    expect(screen.getByText("Planner failed hard")).toBeInTheDocument();
+    expect(container.querySelector(".detail-error-alert")).toBeInTheDocument();
+  });
+
+  it("keeps failed-task banner visible while Activity is expanded", async () => {
+    const user = userEvent.setup();
+    const { container } = render(
+      <TaskDetailModal
+        initialTab="chat"
+        taskDetailChatFirst
+        task={makeTask({ column: "todo" as any, status: "failed", error: "Activity failure stays visible" })}
+        onClose={noop}
+        onMoveTask={noopMove}
+        onDeleteTask={noopDelete}
+        onMergeTask={noopMerge}
+        onOpenDetail={noopOpenDetail}
+        addToast={noop}
+      />,
+    );
+    const detail = container.querySelector(".task-detail-content");
+
+    expect(screen.getByText("Task Failed")).toBeInTheDocument();
+    expect(screen.getByText("Activity failure stays visible")).toBeInTheDocument();
+
+    await user.click(screen.getByTestId("task-chat-expand-toggle"));
+
+    expect(detail).toHaveClass("task-detail-content--chat-expanded");
+    expect(detail).not.toHaveClass("task-detail-content--planner-chat-expanded");
+    expect(screen.getByText("Task Failed")).toBeInTheDocument();
+    expect(screen.getByText("Activity failure stays visible")).toBeInTheDocument();
+    expect(container.querySelector(".detail-error-alert")).toBeInTheDocument();
+  });
+
+  it("does not render empty failed-task alert shells for non-failed or errorless failed tasks", () => {
+    const { container, rerender } = render(
+      <TaskDetailModal
+        initialTab="planner-chat"
+        taskDetailChatFirst
+        task={makeTask({ column: "todo" as any, status: "failed" })}
+        onClose={noop}
+        onMoveTask={noopMove}
+        onDeleteTask={noopDelete}
+        onMergeTask={noopMerge}
+        onOpenDetail={noopOpenDetail}
+        addToast={noop}
+      />,
+    );
+
+    expect(screen.queryByText("Task Failed")).not.toBeInTheDocument();
+    expect(container.querySelector(".detail-error-alert")).toBeNull();
+
+    rerender(
+      <TaskDetailModal
+        initialTab="planner-chat"
+        taskDetailChatFirst
+        task={makeTask({ column: "todo" as any, status: "in-progress", error: "Ignored because task is not failed" })}
+        onClose={noop}
+        onMoveTask={noopMove}
+        onDeleteTask={noopDelete}
+        onMergeTask={noopMerge}
+        onOpenDetail={noopOpenDetail}
+        addToast={noop}
+      />,
+    );
+
+    expect(screen.queryByText("Task Failed")).not.toBeInTheDocument();
+    expect(container.querySelector(".detail-error-alert")).toBeNull();
+  });
 });
 
 describe("TaskDetailModal summarize title action", () => {