Fix settings host sections showing "host not found" when the local daemon is stopped (#1749)

The local daemon's serverId persists while the daemon is stopped, so it isn't
among the connected hosts. The settings host-section resolver fell back to it
without checking it was connected, resolving the section to an unknown id and
rendering "host not found".

Extract the fallback into resolveActiveHostServerId, which only uses a serverId
when it names a currently connected host (covering both the picker selection and
the local daemon), and add regression tests.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/app/src/screens/settings-screen.tsx

@@ -56,7 +56,11 @@ import {
 } from "@/hooks/use-settings";
 import { useHostRuntimeIsConnected, useHosts } from "@/runtime/host-runtime";
 import { useSessionStore } from "@/stores/session-store";
-import { orderHostsLocalFirst, type HostProfile } from "@/types/host-connection";
+import {
+  orderHostsLocalFirst,
+  resolveActiveHostServerId,
+  type HostProfile,
+} from "@/types/host-connection";
 import { TitlebarDragRegion } from "@/components/desktop/titlebar-drag-region";
 import { WindowChromeRegion, WindowChromeSafeArea } from "@/utils/desktop-window";
 import { confirmDialog } from "@/utils/confirm-dialog";
@@ -1144,15 +1148,6 @@ export default function SettingsScreen({ view, openAddHostIntent = null }: Setti
   const [selectedSettingsHostServerId, setSelectedSettingsHostServerId] = useState<string | null>(
     view.kind === "host" ? view.serverId : null,
   );
-  const knownSelectedSettingsHostServerId = useMemo(() => {
-    if (!selectedSettingsHostServerId) {
-      return null;
-    }
-    return hosts.some((host) => host.serverId === selectedSettingsHostServerId)
-      ? selectedSettingsHostServerId
-      : null;
-  }, [hosts, selectedSettingsHostServerId]);
-
   useEffect(() => {
     if (view.kind === "host") {
       setSelectedSettingsHostServerId(view.serverId);
@@ -1160,11 +1155,16 @@ export default function SettingsScreen({ view, openAddHostIntent = null }: Setti
   }, [view]);
 
   // The host the four sections scope to: the host on the active view, otherwise
-  // the picker choice, otherwise the local daemon, otherwise the first host.
+  // the picker choice, otherwise the connected local daemon, otherwise the first host.
   const activeHostServerId = useMemo(() => {
     if (view.kind === "host") return view.serverId;
-    return knownSelectedSettingsHostServerId ?? localServerId ?? sortedHosts[0]?.serverId ?? null;
-  }, [view, knownSelectedSettingsHostServerId, localServerId, sortedHosts]);
+    return resolveActiveHostServerId({
+      selectedServerId: selectedSettingsHostServerId,
+      localServerId,
+      hosts,
+      orderedHosts: sortedHosts,
+    });
+  }, [view, selectedSettingsHostServerId, localServerId, hosts, sortedHosts]);
 
   const handleSendBehaviorChange = useCallback(
     (behavior: SendBehavior) => {