fix(mobile): one way to select a page, so split view stops pushing

apps/mobile/src/App.tsx

@@ -6,7 +6,12 @@ import { StatusBar } from "react-native";
 import { GestureHandlerRootView } from "react-native-gesture-handler";
 import { KeyboardProvider } from "react-native-keyboard-controller";
 import { SafeAreaProvider } from "react-native-safe-area-context";
-import { createStaticNavigation, getStateFromPath } from "@react-navigation/native";
+import {
+  createNavigationContainerRef,
+  createStaticNavigation,
+  getActionFromState,
+  getStateFromPath,
+} from "@react-navigation/native";
 
 import { RegistryContext } from "@effect/atom-react";
 import { ProjectChipIconRasterizer } from "./native/ProjectChipIconImages";
@@ -38,6 +43,7 @@ import {
   recordWorkspaceSelections,
   settingsLinkPage,
 } from "./features/workspace/workspace-selection-store";
+import { workspaceDetailLinkAction } from "./features/workspace/workspace-detail-selection";
 import { NativeLayoutMetricsProvider } from "./native/native-layout-metrics";
 
 import "../global.css";
@@ -54,6 +60,13 @@ const appLinking = {
   config: { initialRouteName: "Home" },
   filter: shouldHandleAppLink,
   getInitialURL: async () => (await Linking.getInitialURL()) ?? (await launchWorkspaceURL()),
+  getActionFromState: (
+    state: Parameters<typeof getActionFromState>[0],
+    options: Parameters<typeof getActionFromState>[1],
+  ): ReturnType<typeof getActionFromState> =>
+    // Our router handles the selection; React Navigation's type only lists its own actions.
+    (workspaceDetailLinkAction(state) as ReturnType<typeof getActionFromState>) ??
+    getActionFromState(state, options),
   getStateFromPath: (path: string, options: Parameters<typeof getStateFromPath>[1]) =>
     restoreSettingsLinkState(
       restoreDraftLinkState(getStateFromPath(path, options), path),
@@ -62,6 +75,7 @@ const appLinking = {
 };
 
 const Navigation = createStaticNavigation(RootStack);
+const navigationRef = createNavigationContainerRef();
 
 function SplashScreenCoordinator() {
   const { isReady } = useAppearancePreferences();
@@ -116,7 +130,9 @@ function AppContent() {
                 <NativeLayoutMetricsProvider>
                   <IncomingShareProvider>
                     <Navigation
+                      ref={navigationRef}
                       linking={appLinking}
+                      onReady={() => recordWorkspaceSelections(navigationRef.getRootState())}
                       theme={navigationTheme}
                       onStateChange={recordWorkspaceSelections}
                     />

apps/mobile/src/Stack.tsx

@@ -149,6 +149,10 @@ import { nativeHeaderScrollEdgeEffects } from "./native/StackHeader";
 import { HORIZONTAL_FORM_SHEET_OPTIONS, formSheetDetents } from "./native/sheet-surface";
 import { useThreadOutboxDrain } from "./state/use-thread-outbox-drain";
 import { useComposerAttachmentUploadWorker } from "./state/composer-attachment-uploads";
+import {
+  selectWorkspaceDetail,
+  workspaceDetailRouter,
+} from "./features/workspace/workspace-detail-selection";
 
 const HEADER_SCROLL_EDGE_EFFECTS = nativeHeaderScrollEdgeEffects(Platform.OS, Platform.Version);
 
@@ -525,7 +529,12 @@ function RootStackLayout(props: {
     if (!transition.shareIdToPresent) {
       return;
     }
-    navigation.navigate("Thread", { draft: { incomingShareId: transition.shareIdToPresent } });
+    navigation.dispatch(
+      selectWorkspaceDetail({
+        name: "Thread",
+        params: { draft: { incomingShareId: transition.shareIdToPresent } },
+      }),
+    );
   }, [navigation, pendingShare, props.state]);
 
   return (
@@ -599,6 +608,7 @@ function NotFoundScreen() {
 
 const RootStackConfig = createWorkspaceStackNavigator({
   initialRouteName: "Home",
+  UNSTABLE_router: workspaceDetailRouter,
   // React Navigation calls layouts inline; compiled components would share the navigator's memo cache.
   layout: (props) => <RootStackLayout {...props} />,
   screenOptions: {

apps/mobile/src/features/files/ThreadFilesRouteScreen.tsx

@@ -22,7 +22,6 @@ import { AudioFilePreview } from "./AudioFilePreview";
 import { EmptyState } from "../../components/ui/EmptyState";
 import { FilePreviewModal, type FilePreviewSource } from "../../components/FilePreviewModal";
 import { LoadingScreen } from "../../components/LoadingScreen";
-import { resolveFileSelectionNavigationAction } from "../../lib/adaptive-navigation";
 import { copyTextWithHaptic } from "../../lib/copyTextWithHaptic";
 import { isPdfFile } from "../../lib/filePreview";
 import { tryOpenExternalUrl } from "../../lib/openExternalUrl";
@@ -478,10 +477,7 @@ export function ThreadFilesTreeScreen(props: ThreadFilesRouteScreenProps) {
       navigation.navigate("NewTaskFile", params);
       return;
     }
-    const navigationAction = resolveFileSelectionNavigationAction({
-      hasPersistentFileInspector: hasFileInspector,
-    });
-    if (navigationAction === "replace") {
+    if (hasFileInspector) {
       navigation.dispatch(StackActions.replace("ThreadFile", params));
       return;
     }

apps/mobile/src/features/home/HomeRouteScreen.tsx

@@ -28,14 +28,14 @@ import { HomeScreen } from "./HomeScreen";
 import { HomeHeader } from "./HomeHeader";
 import { useHomeListOptions } from "./home-list-options";
 import { useAtomValueWhileVisible, useHomeRouteVisible } from "./home-route-visibility";
-import { useHomeThreadRouteSelection, useHomeThreadSelection } from "./home-thread-navigation";
 import { buildHomeProjectScopes } from "./homeThreadList";
 import { usePendingTaskListActions } from "./usePendingTaskListActions";
 import { useThreadListActions } from "./useThreadListActions";
 import { getConnectionAwareBrandHeaderOptions } from "./WorkspaceConnectionTitle";
 import { useWorkspaceTabs } from "../workspace/WorkspaceTabsContext";
 import { openSettings } from "../settings/settings-navigation";
 import { useSelectWorkspaceTab } from "../workspace/useSelectWorkspaceTab";
+import { useSelectWorkspaceDetail } from "../workspace/useSelectWorkspaceDetail";
 
 export function HomeRouteScreen() {
   const { width: windowWidth } = useWindowDimensions();
@@ -45,6 +45,7 @@ export function HomeRouteScreen() {
   const headerWidth = nativePrimaryColumn ? (columnMetrics?.width ?? windowWidth) : windowWidth;
   const { layout, panes, primarySidebarSearchQuery, setPrimarySidebarSearchQuery, startNewTask } =
     useAdaptiveWorkspaceLayout();
+  const selectDetail = useSelectWorkspaceDetail();
   const projects = useProjects();
   // Stop rebuilding the streaming thread list while Thread covers Home.
   const visible = useHomeRouteVisible();
@@ -67,8 +68,18 @@ export function HomeRouteScreen() {
     else if (workspace) workspace.dispatch({ type: "query", query, tab: "threads" });
     else setLocalSearchQuery(query);
   };
-  const handleSelectThread = useHomeThreadSelection();
-  const selectThreadRoute = useHomeThreadRouteSelection();
+  const handleSelectThread = useCallback(
+    (thread: EnvironmentThreadShell) =>
+      selectDetail({
+        name: "Thread",
+        params: { environmentId: String(thread.environmentId), threadId: String(thread.id) },
+      }),
+    [selectDetail],
+  );
+  const selectThreadRoute = useCallback(
+    (params: ReactNavigation.RootParamList["Thread"]) => selectDetail({ name: "Thread", params }),
+    [selectDetail],
+  );
   const handleNewThreadOnBranch = useCallback(
     (thread: EnvironmentThreadShell) => {
       selectThreadRoute({
@@ -104,7 +115,8 @@ export function HomeRouteScreen() {
     unsettleThread,
   } = useThreadListActions();
   const pendingTasks = usePendingNewTasks();
-  const { openPendingTask, confirmDeletePendingTask } = usePendingTaskListActions();
+  const { openPendingTask, confirmDeletePendingTask } =
+    usePendingTaskListActions(selectThreadRoute);
   const environments = useMemo(() => {
     const connectionStateByEnvironmentId = new Map(
       workspaceEnvironments.map(