Scope workspace context state by session

app/lib/providers/recent_sessions.dart

@@ -25,6 +25,7 @@ import 'device_provisioning.dart';
 import 'projects.dart';
 import 'recent_agents.dart';
 import 'sessions.dart';
+import 'session_workspace_state.dart';
 import 'ui_attention_providers.dart';
 import 'agent_transport.dart';
 
@@ -470,6 +471,7 @@ Future<RecentSessionDeleteOutcome> deleteRecentSession(
       // that does not is merely stale under an id that never comes back.
       if (ack == SessionDeleteAck.deleted) {
         clearChatComposerDraft(ref, row.session.id);
+        clearSessionWorkspaceState(ref, o.registrationId, row.session.id);
       }
       return switch (ack) {
         SessionDeleteAck.deleted => RecentSessionDeleteOutcome.deleted,
@@ -530,6 +532,7 @@ Future<RecentSessionDeleteOutcome> deleteRecentSession(
   await store.put(o.registrationId, next);
   await store.flushNow();
   clearChatComposerDraft(ref, row.session.id);
+  clearSessionWorkspaceState(ref, o.registrationId, row.session.id);
   return RecentSessionDeleteOutcome.deleted;
 }
 

app/lib/providers/session_workspace_state.dart

@@ -0,0 +1,92 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../models/workspace_view.dart';
+import 'agent_transport.dart';
+import 'sessions.dart';
+
+typedef SessionUiKey = ({String entryId, String sessionId});
+
+class SessionWorkspaceState {
+  const SessionWorkspaceState({
+    this.initialized = false,
+    this.selectedView = WorkspaceView.files,
+    this.panelMode,
+    this.mobilePage = 0,
+    this.tabletContextOpen = false,
+    this.tabletContextExpanded = false,
+    this.pinnedTerminalId,
+    this.pushedTerminalId,
+  });
+
+  final bool initialized;
+  final WorkspaceView selectedView;
+  final String? panelMode;
+  final int mobilePage;
+  final bool tabletContextOpen;
+  final bool tabletContextExpanded;
+  final String? pinnedTerminalId;
+  final String? pushedTerminalId;
+
+  SessionWorkspaceState copyWith({
+    bool? initialized,
+    WorkspaceView? selectedView,
+    String? panelMode,
+    int? mobilePage,
+    bool? tabletContextOpen,
+    bool? tabletContextExpanded,
+    String? pinnedTerminalId,
+    bool clearPinnedTerminalId = false,
+    String? pushedTerminalId,
+    bool clearPushedTerminalId = false,
+  }) => SessionWorkspaceState(
+    initialized: initialized ?? this.initialized,
+    selectedView: selectedView ?? this.selectedView,
+    panelMode: panelMode ?? this.panelMode,
+    mobilePage: mobilePage ?? this.mobilePage,
+    tabletContextOpen: tabletContextOpen ?? this.tabletContextOpen,
+    tabletContextExpanded: tabletContextExpanded ?? this.tabletContextExpanded,
+    pinnedTerminalId: clearPinnedTerminalId
+        ? null
+        : (pinnedTerminalId ?? this.pinnedTerminalId),
+    pushedTerminalId: clearPushedTerminalId
+        ? null
+        : (pushedTerminalId ?? this.pushedTerminalId),
+  );
+}
+
+class SessionWorkspaceController extends Notifier<SessionWorkspaceState> {
+  SessionWorkspaceController(this.key);
+
+  final SessionUiKey key;
+
+  @override
+  SessionWorkspaceState build() => const SessionWorkspaceState();
+
+  void update(SessionWorkspaceState Function(SessionWorkspaceState) change) {
+    state = change(state);
+  }
+}
+
+final sessionWorkspaceStateProvider =
+    NotifierProvider.family<
+      SessionWorkspaceController,
+      SessionWorkspaceState,
+      SessionUiKey
+    >(SessionWorkspaceController.new);
+
+final activeSessionUiKeyProvider = Provider<SessionUiKey?>((ref) {
+  final entryId = ref.watch(selectedRegistrationIdProvider);
+  final sessionId = ref.watch(activeSessionIdProvider);
+  if (entryId == null || sessionId == null) return null;
+  return (entryId: entryId, sessionId: sessionId);
+});
+
+void clearSessionWorkspaceState(
+  ProviderContainer ref,
+  String entryId,
+  String sessionId,
+) {
+  ref.invalidate(
+    sessionWorkspaceStateProvider((entryId: entryId, sessionId: sessionId)),
+  );
+}

app/lib/screens/workspace_shell.dart

@@ -37,6 +37,7 @@ import '../providers/new_session_picker.dart'
 import '../providers/providers.dart';
 import '../providers/relay_error_banner.dart';
 import '../providers/session_search.dart';
+import '../providers/session_workspace_state.dart';
 import '../providers/session_setup.dart';
 import '../providers/sessions.dart';
 import '../providers/supervisor_status.dart';
@@ -131,6 +132,7 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
   /// applied once, while in portrait.
   _PanelMode? _panelMode;
   bool _prefsApplied = false;
+  SessionUiKey? _sessionUiKey;
   final _mobileScaffoldKey = GlobalKey<ScaffoldState>();
 
   /// Desktop-shaped layout, touch platform only: both the projects sidebar
@@ -499,8 +501,9 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
 
   // ── Preferences ──────────────────────────────────────────────────────
 
-  /// Apply preferences, updating state directly (no setState needed when
-  /// called from build — the build will use the updated values immediately).
+  /// Apply preferences, updating the local values immediately. Provider state
+  /// initialization is deferred when this runs during build because Riverpod
+  /// forbids notifying listeners while the widget tree is being built.
   void _applyPrefs(ProjectPreferences prefs) {
     _splitRatio = prefs.splitRatio;
     // An unrecognized name resolves to null — unchosen, so the viewport default
@@ -521,9 +524,53 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
     if (idx >= 0 && idx < WorkspaceView.values.length) {
       _selectedView = WorkspaceView.values[idx];
     }
+    final key = ref.read(activeSessionUiKeyProvider);
+    if (key != null) {
+      final saved = ref.read(sessionWorkspaceStateProvider(key));
+      if (saved.initialized) {
+        _restoreSessionUi(saved);
+      } else {
+        final selectedView = _selectedView;
+        final panelMode = _panelMode?.name;
+        WidgetsBinding.instance.addPostFrameCallback((_) {
+          if (!mounted) return;
+          final current = ref.read(sessionWorkspaceStateProvider(key));
+          if (current.initialized) return;
+          ref
+              .read(sessionWorkspaceStateProvider(key).notifier)
+              .update(
+                (s) => s.copyWith(
+                  initialized: true,
+                  selectedView: selectedView,
+                  panelMode: panelMode,
+                ),
+              );
+        });
+      }
+      _sessionUiKey = key;
+    }
     _prefsApplied = true;
   }
 
+  void _restoreSessionUi(SessionWorkspaceState state) {
+    _selectedView = state.selectedView;
+    _panelMode = state.panelMode == null
+        ? null
+        : _PanelMode.values.asNameMap()[state.panelMode];
+    _tabletEndDrawerOpen = state.tabletContextOpen;
+    _tabletContextPanelExpanded = state.tabletContextExpanded;
+  }
+
+  void _updateSessionUi(
+    SessionWorkspaceState Function(SessionWorkspaceState) change,
+  ) {
+    final key = _sessionUiKey ?? ref.read(activeSessionUiKeyProvider);
+    if (key == null) return;
+    ref
+        .read(sessionWorkspaceStateProvider(key).notifier)
+        .update((state) => change(state).copyWith(initialized: true));
+  }
+
   void _updatePrefs() {
     // `projectPreferencesProvider` skips the demo, so `PreferencesService` is
     // still bound to the LAST REAL project — a split drag or tab switch inside
@@ -800,6 +847,40 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
 
   @override
   Widget build(BuildContext context) {
+    ref.listen<SessionUiKey?>(activeSessionUiKeyProvider, (previous, next) {
+      if (next == null || next == previous) return;
+      _sessionUiKey = next;
+      var saved = ref.read(sessionWorkspaceStateProvider(next));
+      if (!saved.initialized) {
+        final prefsService = ref.read(preferencesServiceProvider);
+        // The session can be selected while this project's asynchronous
+        // preference load is still in flight. `_applyPrefs` will seed it once
+        // the load lands; using `current` here would copy the previous
+        // project's layout into the new session.
+        if (prefsService.projectId != next.entryId) return;
+        final prefs = prefsService.current;
+        final idx = prefs.workspaceViewIndex;
+        saved = saved.copyWith(
+          initialized: true,
+          selectedView: idx >= 0 && idx < WorkspaceView.values.length
+              ? WorkspaceView.values[idx]
+              : WorkspaceView.files,
+          panelMode: prefs.panelMode,
+        );
+        ref
+            .read(sessionWorkspaceStateProvider(next).notifier)
+            .update((_) => saved);
+      }
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        if (!mounted || ref.read(activeSessionUiKeyProvider) != next) return;
+        setState(() => _restoreSessionUi(saved));
+        if (_pageController.hasClients &&
+            _pageController.page?.round() != saved.mobilePage) {
+          _pageController.jumpToPage(saved.mobilePage);
+        }
+      });
+    });
+
     // Subsequent project switches (A → B while WorkspaceShell stays mounted)
     // bootstrap via this listener. The *initial* mount is handled by the
     // initState post-frame callback below: WorkspaceShell is only built
@@ -1266,6 +1347,7 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
   }
 
   void _publishVisibleSurfaces(int page) {
+    _updateSessionUi((s) => s.copyWith(mobilePage: page));
     ref
         .read(agentSurfaceVisibleProvider.notifier)
         .set(page == _MobilePage.agent);
@@ -1363,6 +1445,7 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
   void _selectView(WorkspaceView view) {
     setState(() {
       _selectedView = view;
+      _updateSessionUi((s) => s.copyWith(selectedView: view));
       _updatePrefs();
     });
     ref.read(visibleWorkspaceViewProvider.notifier).set(view);
@@ -1381,7 +1464,10 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
       return;
     }
     if (_effectivePanelMode == _PanelMode.contextHidden) {
-      setState(() => _panelMode = _PanelMode.normal);
+      setState(() {
+        _panelMode = _PanelMode.normal;
+        _updateSessionUi((s) => s.copyWith(panelMode: _panelMode!.name));
+      });
     }
   }
 
@@ -1815,22 +1901,31 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
   }
 
   void _setTabletContextExpanded(bool expanded) {
-    setState(() => _tabletContextPanelExpanded = expanded);
+    setState(() {
+      _tabletContextPanelExpanded = expanded;
+      _updateSessionUi((s) => s.copyWith(tabletContextExpanded: expanded));
+    });
   }
 
   /// Opens the touch tablet's context pane — reached only from
   /// [_openContextPanel]'s tablet branch, since no fling opens the pane (see
   /// [_tabletFlingLeftward]).
   void _openTabletContextPanel() {
     if (_tabletEndDrawerOpen) return;
-    setState(() => _tabletEndDrawerOpen = true);
+    setState(() {
+      _tabletEndDrawerOpen = true;
+      _updateSessionUi((s) => s.copyWith(tabletContextOpen: true));
+    });
   }
 
   /// Closes the touch tablet's context pane — the shared tail of its two
   /// close paths ([_closeTabletDrawers]'s back handler and the close button in
   /// the pane's own tab bar).
   void _closeTabletContextPanel() {
-    setState(() => _tabletEndDrawerOpen = false);
+    setState(() {
+      _tabletEndDrawerOpen = false;
+      _updateSessionUi((s) => s.copyWith(tabletContextOpen: false));
+    });
   }
 
   /// Closes whichever of the touch tablet's sidebar/context pane is open —
@@ -1907,6 +2002,7 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
       _panelMode = _effectivePanelMode == _PanelMode.contextHidden
           ? _PanelMode.normal
           : _PanelMode.contextHidden;
+      _updateSessionUi((s) => s.copyWith(panelMode: _panelMode!.name));
       _updatePrefs();
     });
   }
@@ -1917,6 +2013,7 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
   void _hideContextPanel() {
     setState(() {
       _panelMode = _PanelMode.contextHidden;
+      _updateSessionUi((s) => s.copyWith(panelMode: _panelMode!.name));
       _updatePrefs();
     });
   }
@@ -1961,6 +2058,9 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
                 isExpanded: false,
                 onToggleExpand: () => setState(() {
                   _panelMode = _PanelMode.contextExpanded;
+                  _updateSessionUi(
+                    (s) => s.copyWith(panelMode: _panelMode!.name),
+                  );
                   _updatePrefs();
                 }),
                 onClose: _hideContextPanel,
@@ -1992,6 +2092,9 @@ class WorkspaceShellState extends ConsumerState<WorkspaceShell>
               isExpanded: true,
               onToggleExpand: () => setState(() {
                 _panelMode = _PanelMode.normal;
+                _updateSessionUi(
+                  (s) => s.copyWith(panelMode: _panelMode!.name),
+                );
                 _updatePrefs();
               }),
               onClose: _hideContextPanel,

app/lib/widgets/session_row.dart

@@ -26,6 +26,7 @@ import '../providers/open_checkout.dart';
 import '../providers/project_work_status.dart';
 import '../providers/providers.dart';
 import '../providers/session_delete_pending.dart';
+import '../providers/session_workspace_state.dart';
 import '../providers/session_setup.dart';
 import '../providers/sessions.dart';
 import '../providers/ui_attention_providers.dart';
@@ -847,6 +848,7 @@ class _SessionMenu extends ConsumerWidget {
           final archived = await svc.archive(session.id);
           if (archived != null) {
             clearChatComposerDraft(ref, session.id);
+            clearSessionWorkspaceState(ref, entryId, session.id);
           }
           _disconnectIfEmpty(ref);
         case _SessionAction.delete:
@@ -914,6 +916,7 @@ class _SessionMenu extends ConsumerWidget {
     );
     if (result == SessionDeleteResult.deleted) {
       clearChatComposerDraft(ref, capturedId);
+      clearSessionWorkspaceState(ref, entryId, capturedId);
       _disconnectIfEmpty(ref);
     }
   }