Sync artifact sidebar with selected task

lib/widgets/assistant_artifact_sidebar.dart

@@ -76,6 +76,8 @@ class _AssistantArtifactSidebarState extends State<AssistantArtifactSidebar> {
   bool _loadingSnapshot = false;
   bool _loadingPreview = false;
   bool _taskContextExpanded = false;
+  int _snapshotLoadGeneration = 0;
+  int _previewLoadGeneration = 0;
   Timer? _refreshTimer;
 
   @override
@@ -88,14 +90,23 @@ class _AssistantArtifactSidebarState extends State<AssistantArtifactSidebar> {
   @override
   void didUpdateWidget(covariant AssistantArtifactSidebar oldWidget) {
     super.didUpdateWidget(oldWidget);
-    if (oldWidget.sessionKey != widget.sessionKey ||
+    final workspaceChanged =
+        oldWidget.sessionKey != widget.sessionKey ||
         oldWidget.workspacePath != widget.workspacePath ||
-        oldWidget.workspaceKind != widget.workspaceKind ||
+        oldWidget.workspaceKind != widget.workspaceKind;
+    if (workspaceChanged ||
         oldWidget.artifactSyncAtMs != widget.artifactSyncAtMs ||
         oldWidget.artifactSyncStatus != widget.artifactSyncStatus) {
-      _activeTab = AssistantArtifactSidebarTab.files;
-      _selectedEntry = null;
-      _preview = const AssistantArtifactPreview.empty();
+      if (workspaceChanged) {
+        _activeTab = AssistantArtifactSidebarTab.files;
+        _snapshot = null;
+        _selectedEntry = null;
+        _preview = const AssistantArtifactPreview.empty();
+        _loadError = null;
+        _loadingSnapshot = false;
+        _loadingPreview = false;
+        _previewLoadGeneration += 1;
+      }
       unawaited(_refreshSnapshot());
     }
     _syncRefreshTimer();
@@ -461,13 +472,17 @@ class _AssistantArtifactSidebarState extends State<AssistantArtifactSidebar> {
     if (_loadingSnapshot) {
       return;
     }
+    final generation = ++_snapshotLoadGeneration;
+    final sessionKey = widget.sessionKey;
     setState(() {
       _loadingSnapshot = true;
       _loadError = null;
     });
     try {
       final snapshot = await widget.loadSnapshot();
-      if (!mounted) {
+      if (!mounted ||
+          generation != _snapshotLoadGeneration ||
+          sessionKey != widget.sessionKey) {
         return;
       }
       final nextSelected = _reconcileSelection(
@@ -484,7 +499,9 @@ class _AssistantArtifactSidebarState extends State<AssistantArtifactSidebar> {
         await _loadPreview(nextSelected);
       }
     } catch (error) {
-      if (!mounted) {
+      if (!mounted ||
+          generation != _snapshotLoadGeneration ||
+          sessionKey != widget.sessionKey) {
         return;
       }
       setState(() {
@@ -555,13 +572,19 @@ class _AssistantArtifactSidebarState extends State<AssistantArtifactSidebar> {
   }
 
   Future<void> _loadPreview(AssistantArtifactEntry entry) async {
+    final generation = ++_previewLoadGeneration;
+    final sessionKey = widget.sessionKey;
+    final relativePath = entry.relativePath;
     setState(() {
       _loadingPreview = true;
       _preview = const AssistantArtifactPreview.empty();
     });
     try {
       final preview = await widget.loadPreview(entry);
-      if (!mounted) {
+      if (!mounted ||
+          generation != _previewLoadGeneration ||
+          sessionKey != widget.sessionKey ||
+          relativePath != _selectedEntry?.relativePath) {
         return;
       }
       setState(() {
@@ -569,7 +592,10 @@ class _AssistantArtifactSidebarState extends State<AssistantArtifactSidebar> {
         _loadingPreview = false;
       });
     } catch (error) {
-      if (!mounted) {
+      if (!mounted ||
+          generation != _previewLoadGeneration ||
+          sessionKey != widget.sessionKey ||
+          relativePath != _selectedEntry?.relativePath) {
         return;
       }
       setState(() {

test/features/assistant/assistant_artifact_sidebar_test.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:xworkmate/runtime/assistant_artifacts.dart';
@@ -46,6 +48,85 @@ void main() {
     expect(find.text('artifact-2.txt'), findsAtLeastNWidgets(1));
   });
 
+  testWidgets(
+    'clears stale artifacts and ignores late snapshot after task switch',
+    (tester) async {
+      final firstSnapshot = Completer<AssistantArtifactSnapshot>();
+      var sessionKey = 'task-a';
+      var workspacePath = '/tmp/task-a';
+
+      Future<AssistantArtifactSnapshot> loadSnapshot() {
+        final capturedSessionKey = sessionKey;
+        if (capturedSessionKey == 'task-a') {
+          return firstSnapshot.future;
+        }
+        return Future<AssistantArtifactSnapshot>.value(
+          AssistantArtifactSnapshot(
+            workspacePath: '/tmp/task-b',
+            workspaceKind: WorkspaceRefKind.localPath,
+            fileEntries: const <AssistantArtifactEntry>[
+              AssistantArtifactEntry(
+                id: 'task-b-entry',
+                label: 'task-b.md',
+                relativePath: 'task-b.md',
+                kind: AssistantArtifactEntryKind.file,
+                mimeType: 'text/markdown',
+                previewable: true,
+                workspacePath: '/tmp/task-b',
+              ),
+            ],
+          ),
+        );
+      }
+
+      await tester.pumpWidget(
+        _buildTestApp(
+          sessionKey: sessionKey,
+          workspacePath: workspacePath,
+          artifactSyncAtMs: 1,
+          loadSnapshot: loadSnapshot,
+        ),
+      );
+      await tester.pump();
+
+      sessionKey = 'task-b';
+      workspacePath = '/tmp/task-b';
+      await tester.pumpWidget(
+        _buildTestApp(
+          sessionKey: sessionKey,
+          workspacePath: workspacePath,
+          artifactSyncAtMs: 1,
+          loadSnapshot: loadSnapshot,
+        ),
+      );
+      await tester.pump();
+
+      expect(find.text('task-a.md'), findsNothing);
+
+      firstSnapshot.complete(
+        AssistantArtifactSnapshot(
+          workspacePath: '/tmp/task-a',
+          workspaceKind: WorkspaceRefKind.localPath,
+          fileEntries: const <AssistantArtifactEntry>[
+            AssistantArtifactEntry(
+              id: 'task-a-entry',
+              label: 'task-a.md',
+              relativePath: 'task-a.md',
+              kind: AssistantArtifactEntryKind.file,
+              mimeType: 'text/markdown',
+              previewable: true,
+              workspacePath: '/tmp/task-a',
+            ),
+          ],
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('task-a.md'), findsNothing);
+      expect(find.text('task-b.md'), findsAtLeastNWidgets(1));
+    },
+  );
+
   testWidgets('keeps polling partial artifact snapshots', (tester) async {
     var loadCount = 0;
 
@@ -242,6 +323,8 @@ void main() {
 }
 
 Widget _buildTestApp({
+  String sessionKey = 'unit-fixture-task-a',
+  String workspacePath = '/tmp/thread',
   required double artifactSyncAtMs,
   String artifactSyncStatus = '',
   required Future<AssistantArtifactSnapshot> Function() loadSnapshot,
@@ -256,9 +339,9 @@ Widget _buildTestApp({
         width: 460,
         height: 640,
         child: AssistantArtifactSidebar(
-          sessionKey: 'unit-fixture-task-a',
+          sessionKey: sessionKey,
           threadTitle: 'Thread',
-          workspacePath: '/tmp/thread',
+          workspacePath: workspacePath,
           workspaceKind: WorkspaceRefKind.localPath,
           artifactSyncAtMs: artifactSyncAtMs,
           artifactSyncStatus: artifactSyncStatus,