`render_buffer` computed the dashboard-fallback flag once at entry, then
ran `show_buffer_tabs` which can close the last buffer via a tab's ✕
button. The trailing `show_active_buffer` then unwrapped a now-None
`active_buffer` and panicked.

Guard the call via a free helper so the added branch stays off
`app_layout::CkEditorApp`'s cyclomatic baseline, matching the pattern
already used by `dashboard_keyboard_focused`.

@@ -0,0 +52,4 @@
+    // the bridge, write SERVER_TO_CLIENT back. This stands in for the
+    // bus's rmcp::Server serving a tool call.
+    let server_handle = tokio::spawn(async move {
+        let (mut stream, _) = listener.accept().await.unwrap();

@@ -0,0 +52,4 @@
+        let Some(ctx) = project.contexts.get(&id) else {
+            return;
+        };
+        ctx.kind.clone()

@@ -0,0 +91,4 @@
+    loop {
+        drain_requests(&mut bus.receiver, coord, buffers);
+        if task.is_finished() {
+            return task.await.expect("task panicked");