perf: Phase 1 critical performance fixes + production macOS build

Performance:
- Move JSON parsing to background isolate via Isolate.run() (eliminates 2-4s UI freeze)
- Cache filteredEntries with key-based invalidation (eliminates O(n) recomputation)
- Debounce search queries at 300ms (prevents cascade rebuilds on keystroke)
- Flatten timeline from 2-level turn×response Column to single virtualized ListView.builder
- Add RepaintBoundary per timeline item (isolates repaints during scroll)
- Use context.select for granular rebuilds instead of top-level context.watch
- Lazy ExpandableCard: child not built until first expand (replaces AnimatedCrossFade)
- Use IndexedStack in AppShell (preserves screen state across tab switches)

Fixes:
- Collect parse errors instead of silently swallowing them
- Show parse error count in timeline filter bar
- Fix overflow in tokens screen pie chart legend

Build:
- Configure Developer ID signing with hardened runtime for production distribution
- Enable secure timestamps for notarization
- Update app name to Claude Session Viewer
- Signed, notarized, stapled DMG distribution

lib/providers/session_provider.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/foundation.dart';
 import '../models/agent_info.dart';
 import '../models/log_entry.dart';
@@ -10,12 +12,21 @@ class SessionProvider with ChangeNotifier {
   bool _isLoading = false;
   String? _error;
   String? _filePath;
+  List<ParseError> _parseErrors = const [];
 
   // Filter state
   String? _selectedAgentId;
   Set<String> _visibleTypes = {'user', 'assistant', 'system'};
   String _searchQuery = '';
 
+  // Cached filtered results
+  List<LogEntry> _cachedFilteredEntries = const [];
+  // Cache key — tracks what was used to compute the cache
+  _FilterKey? _cachedFilterKey;
+
+  // Debounce timer for search
+  Timer? _searchDebounce;
+
   SessionLog? get session => _session;
   bool get isLoading => _isLoading;
   String? get error => _error;
@@ -23,15 +34,30 @@ class SessionProvider with ChangeNotifier {
   String? get selectedAgentId => _selectedAgentId;
   Set<String> get visibleTypes => _visibleTypes;
   String get searchQuery => _searchQuery;
+  List<ParseError> get parseErrors => _parseErrors;
 
   AgentInfo? get selectedAgent {
     if (_session == null || _selectedAgentId == null) return null;
-    return _session!.agents
+    return _session!.agents.where((a) => a.id == _selectedAgentId).firstOrNull;
-        .where((a) => a.id == _selectedAgentId)
-        .firstOrNull;
   }
 
   List<LogEntry> get filteredEntries {
+    final key = _FilterKey(
+      selectedAgentId: _selectedAgentId,
+      visibleTypes: _visibleTypes,
+      searchQuery: _searchQuery,
+      hasSession: _session != null,
+    );
+
+    if (_cachedFilterKey == key) return _cachedFilteredEntries;
+
+    // Recompute
+    _cachedFilterKey = key;
+    _cachedFilteredEntries = _computeFilteredEntries();
+    return _cachedFilteredEntries;
+  }
+
+  List<LogEntry> _computeFilteredEntries() {
     if (_session == null) return [];
 
     List<LogEntry> entries;
@@ -73,10 +99,14 @@ class SessionProvider with ChangeNotifier {
     _filePath = filePath;
     _selectedAgentId = null;
     _searchQuery = '';
+    _parseErrors = const [];
+    _invalidateCache();
     notifyListeners();
 
     try {
-      _session = await _parser.parseFile(filePath);
+      final result = await _parser.parseFile(filePath);
+      _session = result.sessionLog;
+      _parseErrors = result.errors;
       _error = null;
     } catch (e) {
       _error = e.toString();
@@ -89,6 +119,7 @@ class SessionProvider with ChangeNotifier {
 
   void selectAgent(String? agentId) {
     _selectedAgentId = agentId;
+    _invalidateCache();
     notifyListeners();
   }
 
@@ -98,12 +129,18 @@ class SessionProvider with ChangeNotifier {
     } else {
       _visibleTypes = Set.from(_visibleTypes)..add(type);
     }
+    _invalidateCache();
     notifyListeners();
   }
 
   void setSearchQuery(String query) {
     _searchQuery = query;
+    // Update cache immediately but debounce notifyListeners
+    _invalidateCache();
+    _searchDebounce?.cancel();
+    _searchDebounce = Timer(const Duration(milliseconds: 300), () {
       notifyListeners();
+    });
   }
 
   void clearSession() {
@@ -112,6 +149,55 @@ class SessionProvider with ChangeNotifier {
     _error = null;
     _selectedAgentId = null;
     _searchQuery = '';
+    _parseErrors = const [];
+    _searchDebounce?.cancel();
+    _invalidateCache();
     notifyListeners();
   }
+
+  void _invalidateCache() {
+    _cachedFilterKey = null;
+  }
+
+  @override
+  void dispose() {
+    _searchDebounce?.cancel();
+    super.dispose();
+  }
+}
+
+/// Immutable key to detect whether the filter result has changed.
+class _FilterKey {
+  final String? selectedAgentId;
+  final Set<String> visibleTypes;
+  final String searchQuery;
+  final bool hasSession;
+
+  const _FilterKey({
+    required this.selectedAgentId,
+    required this.visibleTypes,
+    required this.searchQuery,
+    required this.hasSession,
+  });
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is _FilterKey &&
+          selectedAgentId == other.selectedAgentId &&
+          _setEquals(visibleTypes, other.visibleTypes) &&
+          searchQuery == other.searchQuery &&
+          hasSession == other.hasSession;
+
+  @override
+  int get hashCode =>
+      Object.hash(selectedAgentId, Object.hashAll(visibleTypes), searchQuery, hasSession);
+
+  static bool _setEquals<T>(Set<T> a, Set<T> b) {
+    if (a.length != b.length) return false;
+    for (final v in a) {
+      if (!b.contains(v)) return false;
+    }
+    return true;
+  }
 }

lib/screens/timeline/timeline_screen.dart

@@ -1,43 +1,212 @@
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
+import '../../models/agent_info.dart';
 import '../../models/log_entry.dart';
 import '../../providers/session_provider.dart';
+import '../../services/jsonl_parser.dart';
 import '../../theme/app_theme.dart';
 import 'widgets/assistant_message_card.dart';
 import 'widgets/system_message_card.dart';
 import 'widgets/user_message_card.dart';
 
-class TimelineScreen extends StatelessWidget {
+// ─── Flat timeline item ──────────────────────────────────────
+
+enum _TimelineItemType { userPrompt, assistantResponse, systemMessage }
+
+class _TimelineItem {
+  final _TimelineItemType type;
+  final LogEntry entry;
+  final int turnNumber;
+  final bool isFirstInTurn;
+  final bool isLastInTurn;
+
+  const _TimelineItem({
+    required this.type,
+    required this.entry,
+    required this.turnNumber,
+    this.isFirstInTurn = false,
+    this.isLastInTurn = false,
+  });
+}
+
+List<_TimelineItem> _flattenTurns(List<LogEntry> entries) {
+  final items = <_TimelineItem>[];
+  UserEntry? currentPrompt;
+  int turnNum = 0;
+  bool hadPrompt = false;
+
+  for (final entry in entries) {
+    if (entry is UserEntry && !entry.isToolResult) {
+      // Flush previous turn
+      if (hadPrompt && currentPrompt != null) {
+        // already flushed — this is a new prompt
+      }
+      if (currentPrompt != null) {
+        // The previous turn is already flushed (items added inline below)
+      }
+
+      // Emit user prompt item
+      turnNum++;
+      currentPrompt = entry;
+      hadPrompt = true;
+
+      items.add(_TimelineItem(
+        type: _TimelineItemType.userPrompt,
+        entry: entry,
+        turnNumber: turnNum,
+        isFirstInTurn: true,
+      ));
+    } else if (entry is UserEntry && entry.isToolResult) {
+      continue;
+    } else if (hadPrompt) {
+      final isAssistant = entry is AssistantEntry;
+      final isSystem = entry is SystemEntry;
+
+      items.add(_TimelineItem(
+        type: isAssistant
+            ? _TimelineItemType.assistantResponse
+            : isSystem
+                ? _TimelineItemType.systemMessage
+                : _TimelineItemType.systemMessage,
+        entry: entry,
+        turnNumber: turnNum,
+      ));
+    }
+    // else: orphaned entries before first user prompt — skip
+  }
+
+  // Mark last item in each turn
+  for (int i = 0; i < items.length; i++) {
+    final nextIsNewTurn =
+        i + 1 >= items.length || items[i + 1].isFirstInTurn;
+    if (!items[i].isFirstInTurn && nextIsNewTurn) {
+      items[i] = _TimelineItem(
+        type: items[i].type,
+        entry: items[i].entry,
+        turnNumber: items[i].turnNumber,
+        isFirstInTurn: items[i].isFirstInTurn,
+        isLastInTurn: true,
+      );
+    }
+  }
+
+  return items;
+}
+
+// ─── Turn grouping for filter bar stats ──────────────────────
+
+class ConversationTurn {
+  final UserEntry prompt;
+  final List<LogEntry> responses;
+  final int turnNumber;
+
+  ConversationTurn({
+    required this.prompt,
+    required this.responses,
+    required this.turnNumber,
+  });
+}
+
+List<ConversationTurn> groupIntoTurns(List<LogEntry> entries) {
+  final turns = <ConversationTurn>[];
+  UserEntry? currentPrompt;
+  List<LogEntry> currentResponses = [];
+  List<LogEntry> orphanedEntries = [];
+  int turnNum = 0;
+
+  for (final entry in entries) {
+    if (entry is UserEntry && !entry.isToolResult) {
+      if (currentPrompt != null) {
+        turns.add(ConversationTurn(
+          prompt: currentPrompt,
+          responses: currentResponses,
+          turnNumber: turnNum,
+        ));
+      }
+      if (orphanedEntries.isNotEmpty) {
+        currentResponses = [];
+        turnNum++;
+        currentPrompt = entry;
+        currentResponses.addAll(orphanedEntries);
+        orphanedEntries = [];
+      } else {
+        currentPrompt = entry;
+        currentResponses = [];
+        turnNum++;
+      }
+    } else if (entry is UserEntry && entry.isToolResult) {
+      continue;
+    } else if (currentPrompt != null) {
+      currentResponses.add(entry);
+    } else {
+      orphanedEntries.add(entry);
+    }
+  }
+
+  if (currentPrompt != null) {
+    turns.add(ConversationTurn(
+      prompt: currentPrompt,
+      responses: currentResponses,
+      turnNumber: turnNum,
+    ));
+  }
+
+  return turns;
+}
+
+// ─── Main screen ──────────────────────────────────────────────
+
+class TimelineScreen extends StatefulWidget {
   const TimelineScreen({super.key});
 
+  @override
+  State<TimelineScreen> createState() => _TimelineScreenState();
+}
+
+class _TimelineScreenState extends State<TimelineScreen> {
+  List<_TimelineItem> _cachedItems = const [];
+  List<LogEntry>? _cachedEntriesKey;
+
   @override
   Widget build(BuildContext context) {
-    final provider = context.watch<SessionProvider>();
+    final session = context.select<SessionProvider, SessionLog?>((p) => p.session);
-    final session = provider.session;
+
     if (session == null) {
       return const Center(
-        child: Text('No session loaded', style: TextStyle(color: AppColors.textMuted)),
+        child: Text('No session loaded',
+            style: TextStyle(color: AppColors.textMuted)),
       );
     }
 
-    final entries = provider.filteredEntries;
+    // Get filtered entries and flatten to items (cached)
+    final entries = context.select<SessionProvider, List<LogEntry>>(
+        (p) => p.filteredEntries);
+
+    // Cache the flat items list — only recompute when entries reference changes
+    if (!identical(_cachedEntriesKey, entries)) {
+      _cachedEntriesKey = entries;
+      _cachedItems = _flattenTurns(entries);
+    }
 
     return Scaffold(
       backgroundColor: AppColors.background,
       body: Column(
         children: [
-          _FilterBar(provider: provider),
+          const _FilterBar(),
           Expanded(
-            child: entries.isEmpty
+            child: _cachedItems.isEmpty
                 ? const Center(
                     child: Text('No matching entries',
                         style: TextStyle(color: AppColors.textMuted)),
                   )
                 : ListView.builder(
                     padding: const EdgeInsets.fromLTRB(24, 8, 24, 24),
-                    itemCount: entries.length,
+                    itemCount: _cachedItems.length,
+                    addRepaintBoundaries: true,
                     itemBuilder: (context, index) {
-                      return _buildEntryCard(entries[index], index);
+                      return _TimelineItemWidget(
+                        item: _cachedItems[index],
+                      );
                     },
                   ),
           ),
@@ -45,38 +214,171 @@ class TimelineScreen extends StatelessWidget {
       ),
     );
   }
+}
 
-  Widget _buildEntryCard(LogEntry entry, int index) {
+// ─── Timeline item widget ────────────────────────────────────
-    if (entry is UserEntry && !entry.isToolResult) {
+
+class _TimelineItemWidget extends StatelessWidget {
+  final _TimelineItem item;
+
+  const _TimelineItemWidget({required this.item});
+
+  @override
+  Widget build(BuildContext context) {
+    final isPrompt = item.type == _TimelineItemType.userPrompt;
+
+    if (isPrompt) {
+      // User prompt — no tree line, just the card with turn indicator
       return Padding(
-        padding: const EdgeInsets.only(bottom: 8),
+        padding: EdgeInsets.only(
-        child: UserMessageCard(entry: entry, index: index),
+          bottom: item.isLastInTurn ? 0 : 6,
+          top: 2,
+        ),
+        child: Row(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            // Turn dot
+            SizedBox(
+              width: 24,
+              child: Column(
+                children: [
+                  const SizedBox(height: 14),
+                  Container(
+                    width: 10,
+                    height: 10,
+                    decoration: BoxDecoration(
+                      color: AppColors.user,
+                      shape: BoxShape.circle,
+                      boxShadow: [
+                        BoxShadow(
+                          color: AppColors.user.withAlpha(60),
+                          blurRadius: 6,
+                          spreadRadius: 1,
+                        ),
+                      ],
+                    ),
+                  ),
+                ],
+              ),
+            ),
+            Expanded(
+              child: Padding(
+                padding: const EdgeInsets.only(bottom: 10),
+                child: RepaintBoundary(
+                  child: UserMessageCard(
+                    entry: item.entry as UserEntry,
+                    index: item.turnNumber,
+                  ),
+                ),
+              ),
+            ),
+          ],
+        ),
       );
     }
-    if (entry is AssistantEntry) {
+
+    // Response/system — with tree connector line
     return Padding(
-        padding: const EdgeInsets.only(bottom: 8),
+      padding: const EdgeInsets.only(bottom: 6),
-        child: AssistantMessageCard(entry: entry, index: index),
+      child: Row(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          // Tree line column
+          SizedBox(
+            width: 24,
+            height: 36, // Fixed height for the connector
+            child: CustomPaint(
+              painter: _TreeLinePainter(
+                color: AppColors.user.withAlpha(60),
+                isLastChild: item.isLastInTurn,
+              ),
+            ),
+          ),
+          Expanded(
+            child: Padding(
+              padding: const EdgeInsets.only(bottom: 4),
+              child: RepaintBoundary(
+                child: _buildCard(item),
+              ),
+            ),
+          ),
+        ],
+      ),
     );
   }
-    if (entry is SystemEntry) {
+
-      return Padding(
+  Widget _buildCard(_TimelineItem item) {
-        padding: const EdgeInsets.only(bottom: 8),
+    if (item.entry is AssistantEntry) {
-        child: SystemMessageCard(entry: entry),
+      return AssistantMessageCard(
+        entry: item.entry as AssistantEntry,
+        index: item.turnNumber,
       );
     }
+    if (item.entry is SystemEntry) {
+      return SystemMessageCard(entry: item.entry as SystemEntry);
+    }
     return const SizedBox.shrink();
   }
 }
 
-class _FilterBar extends StatelessWidget {
+// ─── Custom painter for tree lines ────────────────────────────
-  final SessionProvider provider;
 
-  const _FilterBar({required this.provider});
+class _TreeLinePainter extends CustomPainter {
+  final Color color;
+  final bool isLastChild;
+
+  const _TreeLinePainter({
+    required this.color,
+    required this.isLastChild,
+  });
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final paint = Paint()
+      ..color = color
+      ..strokeWidth = 2
+      ..style = PaintingStyle.stroke
+      ..strokeCap = StrokeCap.round;
+
+    final centerX = size.width / 2;
+    const connectorY = 18.0;
+
+    // Vertical line from top to connector (or to bottom if not last)
+    canvas.drawLine(
+      Offset(centerX, 0),
+      Offset(centerX, isLastChild ? connectorY : size.height),
+      paint,
+    );
+
+    // Horizontal connector to right edge
+    canvas.drawLine(
+      Offset(centerX, connectorY),
+      Offset(size.width, connectorY),
+      paint,
+    );
+  }
+
+  @override
+  bool shouldRepaint(covariant _TreeLinePainter oldDelegate) {
+    return oldDelegate.color != color || oldDelegate.isLastChild != isLastChild;
+  }
+}
+
+// ─── Filter bar ───────────────────────────────────────────────
+
+class _FilterBar extends StatelessWidget {
+  const _FilterBar();
 
   @override
   Widget build(BuildContext context) {
+    final provider = context.watch<SessionProvider>();
     final session = provider.session!;
+    final entries = provider.filteredEntries;
+    final turns = groupIntoTurns(entries);
+
+    // Parse errors warning
+    final parseErrors = context.select<SessionProvider, List<ParseError>>(
+        (p) => p.parseErrors);
 
     return Container(
       padding: const EdgeInsets.fromLTRB(24, 16, 24, 12),
@@ -86,7 +388,10 @@ class _FilterBar extends StatelessWidget {
           bottom: BorderSide(color: AppColors.surfaceBorder, width: 1),
         ),
       ),
-      child: Row(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          Row(
             children: [
               // Session info
               Expanded(
@@ -104,12 +409,22 @@ class _FilterBar extends StatelessWidget {
                     if (session.version != null)
                       _InfoChip(label: 'v${session.version}'),
                     const SizedBox(width: 8),
-                _InfoChip(
+                    _InfoChip(label: '${turns.length} turns'),
-                    label: '${provider.filteredEntries.length} entries'),
                     const SizedBox(width: 8),
                     _InfoChip(
                         label:
                             '${_formatTokens(session.totalUsage.totalTokens)} tokens'),
+                    // Parse errors warning
+                    if (parseErrors.isNotEmpty) ...[
+                      const SizedBox(width: 8),
+                      Tooltip(
+                        message:
+                            '${parseErrors.length} lines could not be parsed',
+                        child: _InfoChip(
+                          label: '⚠ ${parseErrors.length} parse errors',
+                        ),
+                      ),
+                    ],
                   ],
                 ),
               ),
@@ -177,15 +492,17 @@ class _FilterBar extends StatelessWidget {
                 width: 180,
                 child: TextField(
                   onChanged: provider.setSearchQuery,
-              style: const TextStyle(fontSize: 12, color: AppColors.textPrimary),
+                  style: const TextStyle(
+                      fontSize: 12, color: AppColors.textPrimary),
                   decoration: InputDecoration(
                     hintText: 'Search...',
-                hintStyle:
+                    hintStyle: const TextStyle(
-                    const TextStyle(fontSize: 12, color: AppColors.textMuted),
+                        fontSize: 12, color: AppColors.textMuted),
                     prefixIcon: const Icon(Icons.search,
                         size: 16, color: AppColors.textMuted),
                     isDense: true,
-                contentPadding: const EdgeInsets.symmetric(vertical: 8),
+                    contentPadding:
+                        const EdgeInsets.symmetric(vertical: 8),
                     filled: true,
                     fillColor: AppColors.surfaceLight,
                     border: OutlineInputBorder(
@@ -203,6 +520,8 @@ class _FilterBar extends StatelessWidget {
               ),
             ],
           ),
+        ],
+      ),
     );
   }
 

lib/screens/tokens/tokens_screen.dart

@@ -174,6 +174,7 @@ class TokensScreen extends StatelessWidget {
                   ),
                   const SizedBox(width: 24),
                   Expanded(
+                    child: SingleChildScrollView(
                       child: Column(
                       mainAxisAlignment: MainAxisAlignment.center,
                       crossAxisAlignment: CrossAxisAlignment.start,
@@ -226,6 +227,7 @@ class TokensScreen extends StatelessWidget {
                       }).toList(),
                     ),
                     ),
+                  ),
                 ],
               ),
             ),

lib/services/jsonl_parser.dart

@@ -1,79 +1,144 @@
 import 'dart:convert';
-import 'dart:io';
+import 'dart:io' as io;
+import 'dart:isolate';
 
 import '../models/agent_info.dart';
 import '../models/content_block.dart';
 import '../models/log_entry.dart';
 import '../models/token_usage.dart';
 
+class ParseError {
+  final int? line;
+  final String? source;
+  final String error;
+  const ParseError({this.line, this.source, required this.error});
+}
+
+class ParseResult {
+  final SessionLog sessionLog;
+  final List<ParseError> errors;
+  const ParseResult(this.sessionLog, this.errors);
+}
+
+class _IsolateInput {
+  final List<String> mainLines;
+  final String sessionFileName;
+  final Map<String, List<String>> subagentLines;
+  final Map<String, String> subagentMetaRaw;
+  const _IsolateInput({
+    required this.mainLines,
+    required this.sessionFileName,
+    required this.subagentLines,
+    required this.subagentMetaRaw,
+  });
+}
+
 class JsonlParser {
-  Future<SessionLog> parseFile(String filePath) async {
+  Future<ParseResult> parseFile(String filePath) async {
-    final file = File(filePath);
+    final file = io.File(filePath);
-    final lines = await file.readAsLines(encoding: utf8);
+    final mainLines = await file.readAsLines(encoding: utf8);
 
-    final entries = <LogEntry>[];
+    final sessionFileName =
-    for (final line in lines) {
+        file.uri.pathSegments.last.replaceAll('.jsonl', '');
-      if (line.trim().isEmpty) continue;
-      try {
-        final json = jsonDecode(line) as Map<String, dynamic>;
-        entries.add(LogEntry.fromJson(json));
-      } catch (_) {}
-    }
-
-    // Resolve the subagents directory from the session file path
-    // e.g. /path/to/project/64a8386a.jsonl → /path/to/project/64a8386a/subagents/
-    final sessionFileName = file.uri.pathSegments.last.replaceAll('.jsonl', '');
     final parentDir = file.parent.path;
-    final subagentsDir = Directory('$parentDir/$sessionFileName/subagents');
+    final subagentsDir =
+        io.Directory('$parentDir/$sessionFileName/subagents');
+
+    final subagentLines = <String, List<String>>{};
+    final subagentMetaRaw = <String, String>{};
 
-    // Load all subagent .jsonl files
-    final subagentFiles = <String, List<LogEntry>>{};
-    final subagentMeta = <String, Map<String, dynamic>>{};
     if (await subagentsDir.exists()) {
       await for (final entity in subagentsDir.list()) {
-        if (entity is File && entity.path.endsWith('.jsonl')) {
+        if (entity is io.File) {
+          if (entity.path.endsWith('.jsonl')) {
             final agentFileName = entity.uri.pathSegments.last;
-          // agent-a014e30b71de602bb.jsonl → a014e30b71de602bb
             final agentId = agentFileName
                 .replaceAll('.jsonl', '')
                 .replaceFirst('agent-', '');
-
-          final agentEntries = <LogEntry>[];
             try {
-            final agentLines = await entity.readAsLines(encoding: utf8);
+              final lines = await entity.readAsLines(encoding: utf8);
-            for (final line in agentLines) {
+              subagentLines[agentId] = lines;
-              if (line.trim().isEmpty) continue;
-              try {
-                final json = jsonDecode(line) as Map<String, dynamic>;
-                agentEntries.add(LogEntry.fromJson(json));
             } catch (_) {}
-            }
+          } else if (entity.path.endsWith('.meta.json')) {
-          } catch (_) {}
-          if (agentEntries.isNotEmpty) {
-            subagentFiles[agentId] = agentEntries;
-          }
-        } else if (entity is File && entity.path.endsWith('.meta.json')) {
-          try {
-            final metaContent = await entity.readAsString();
-            final meta = jsonDecode(metaContent) as Map<String, dynamic>;
             final agentFileName = entity.uri.pathSegments.last;
             final agentId = agentFileName
                 .replaceAll('.meta.json', '')
                 .replaceFirst('agent-', '');
-            subagentMeta[agentId] = meta;
+            try {
+              subagentMetaRaw[agentId] = await entity.readAsString();
             } catch (_) {}
           }
         }
       }
-
-    return _buildSessionLog(entries, subagentFiles, subagentMeta);
     }
 
-  SessionLog _buildSessionLog(
+    // Run CPU-bound parsing in a background isolate
+    return Isolate.run(
+      () => _parseInIsolate(_IsolateInput(
+        mainLines: mainLines,
+        sessionFileName: sessionFileName,
+        subagentLines: subagentLines,
+        subagentMetaRaw: subagentMetaRaw,
+      )),
+    );
+  }
+}
+
+ParseResult _parseInIsolate(_IsolateInput input) {
+  final errors = <ParseError>[];
+  final entries = <LogEntry>[];
+
+  for (var i = 0; i < input.mainLines.length; i++) {
+    final line = input.mainLines[i];
+    if (line.trim().isEmpty) continue;
+    try {
+      final json = jsonDecode(line) as Map<String, dynamic>;
+      entries.add(LogEntry.fromJson(json));
+    } catch (e) {
+      errors.add(ParseError(line: i, error: e.toString()));
+    }
+  }
+
+  // Parse subagent entries
+  final subagentFiles = <String, List<LogEntry>>{};
+  for (final entry in input.subagentLines.entries) {
+    final agentEntries = <LogEntry>[];
+    for (var i = 0; i < entry.value.length; i++) {
+      final line = entry.value[i];
+      if (line.trim().isEmpty) continue;
+      try {
+        final json = jsonDecode(line) as Map<String, dynamic>;
+        agentEntries.add(LogEntry.fromJson(json));
+      } catch (e) {
+        errors.add(ParseError(
+            line: i, source: entry.key, error: e.toString()));
+      }
+    }
+    if (agentEntries.isNotEmpty) {
+      subagentFiles[entry.key] = agentEntries;
+    }
+  }
+
+  // Parse subagent metadata
+  final subagentMeta = <String, Map<String, dynamic>>{};
+  for (final entry in input.subagentMetaRaw.entries) {
+    try {
+      subagentMeta[entry.key] =
+          jsonDecode(entry.value) as Map<String, dynamic>;
+    } catch (e) {
+      errors.add(ParseError(source: entry.key, error: e.toString()));
+    }
+  }
+
+  final sessionLog = _buildSessionLog(entries, subagentFiles, subagentMeta);
+  return ParseResult(sessionLog, errors);
+}
+
+SessionLog _buildSessionLog(
   List<LogEntry> entries,
   Map<String, List<LogEntry>> subagentFiles,
   Map<String, Map<String, dynamic>> subagentMeta,
-  ) {
+) {
   // Extract metadata from first user/assistant entry
   String? sessionId, cwd, version, gitBranch;
   for (final entry in entries) {
@@ -86,34 +151,24 @@ class JsonlParser {
     }
   }
 
-    // Link tool results to tool use blocks in main session
   _linkToolResults(entries);
-
-    // Link tool results inside each subagent session
   for (final agentEntries in subagentFiles.values) {
     _linkToolResults(agentEntries);
   }
 
-    // Separate main conversation from progress entries
   final mainConversation = entries
-        .where((e) => e.type != 'progress' && e.type != 'file-history-snapshot')
+      .where(
+          (e) => e.type != 'progress' && e.type != 'file-history-snapshot')
       .toList();
 
-    // Build agent info
+  final agents = _buildAgents(mainConversation, subagentFiles, subagentMeta);
-    final agents = _buildAgents(
-      mainConversation,
-      subagentFiles,
-      subagentMeta,
-    );
   final mainAgent = agents.firstWhere((a) => a.id == 'main');
 
-    // Compute total usage
   var totalUsage = const TokenUsage();
   for (final agent in agents) {
     totalUsage = totalUsage + agent.aggregatedUsage;
   }
 
-    // Build tools by name index
   final toolsByName = <String, List<ToolUseBlock>>{};
   for (final agent in agents) {
     for (final tool in agent.toolsUsed) {
@@ -121,7 +176,6 @@ class JsonlParser {
     }
   }
 
-    // Timestamps
   final timestamps = entries
       .where((e) => e.timestamp != null)
       .map((e) => e.timestamp!)
@@ -142,9 +196,9 @@ class JsonlParser {
     startTime: timestamps.isNotEmpty ? timestamps.first : null,
     endTime: timestamps.isNotEmpty ? timestamps.last : null,
   );
-  }
+}
 
-  void _linkToolResults(List<LogEntry> entries) {
+void _linkToolResults(List<LogEntry> entries) {
   final resultMap = <String, ToolResultData>{};
   for (final entry in entries) {
     if (entry is UserEntry && entry.isToolResult) {
@@ -160,16 +214,15 @@ class JsonlParser {
       }
     }
   }
-  }
+}
 
-  List<AgentInfo> _buildAgents(
+List<AgentInfo> _buildAgents(
   List<LogEntry> mainEntries,
   Map<String, List<LogEntry>> subagentFiles,
   Map<String, Map<String, dynamic>> subagentMeta,
-  ) {
+) {
   final agents = <AgentInfo>[];
 
-    // Main agent tools and usage
   final mainToolUses = <ToolUseBlock>[];
   String? mainModel;
   var mainUsage = const TokenUsage();
@@ -197,7 +250,6 @@ class JsonlParser {
     aggregatedUsage: mainUsage,
   ));
 
-    // Find Agent tool calls from the main conversation to get descriptions
   final agentToolCalls = <String, ToolUseBlock>{};
   for (final entry in mainEntries) {
     if (entry is AssistantEntry) {
@@ -209,13 +261,11 @@ class JsonlParser {
     }
   }
 
-    // Build subagent infos from the actual subagent .jsonl files
   for (final entry in subagentFiles.entries) {
     final agentId = entry.key;
     final agentEntries = entry.value;
     final meta = subagentMeta[agentId] ?? {};
 
-      // Extract tool uses, model, and usage from subagent entries
     final subToolUses = <ToolUseBlock>[];
     var subUsage = const TokenUsage();
     String? subModel;
@@ -234,8 +284,6 @@ class JsonlParser {
       }
     }
 
-      // Try to match this subagent to an Agent tool call for description/prompt.
-      // The agentId in the file might be a prefix of the tool_use id.
     ToolUseBlock? matchedCall;
     for (final call in agentToolCalls.entries) {
       if (call.key.contains(agentId) || agentId.contains(call.key)) {
@@ -244,7 +292,6 @@ class JsonlParser {
       }
     }
 
-      // Also check the slug from the first entry to match
     String? slug;
     for (final e in agentEntries) {
       if (e.raw.containsKey('slug')) {
@@ -253,12 +300,10 @@ class JsonlParser {
       }
     }
 
-      final agentType = meta['agentType'] as String? ??
+    final agentType =
-          matchedCall?.subagentType;
+        meta['agentType'] as String? ?? matchedCall?.subagentType;
-      final description = matchedCall?.agentDescription ??
+    final description =
-          slug ??
+        matchedCall?.agentDescription ?? slug ?? agentType ?? 'Subagent';
-          agentType ??
-          'Subagent';
 
     agents.add(AgentInfo(
       id: agentId,
@@ -274,5 +319,4 @@ class JsonlParser {
   }
 
   return agents;
-  }
 }

lib/widgets/common/expandable_card.dart

@@ -26,11 +26,13 @@ class _ExpandableCardState extends State<ExpandableCard>
   late bool _expanded;
   late AnimationController _controller;
   late Animation<double> _rotation;
+  bool _hasBeenExpanded = false; // Track if ever expanded to lazy-build
 
   @override
   void initState() {
     super.initState();
     _expanded = widget.initiallyExpanded;
+    _hasBeenExpanded = _expanded;
     _controller = AnimationController(
       duration: const Duration(milliseconds: 200),
       vsync: this,
@@ -51,6 +53,7 @@ class _ExpandableCardState extends State<ExpandableCard>
     setState(() {
       _expanded = !_expanded;
       if (_expanded) {
+        _hasBeenExpanded = true;
         _controller.forward();
       } else {
         _controller.reverse();
@@ -76,7 +79,8 @@ class _ExpandableCardState extends State<ExpandableCard>
             onTap: _toggle,
             borderRadius: BorderRadius.circular(8),
             child: Padding(
-              padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 10),
+              padding:
+                  const EdgeInsets.symmetric(horizontal: 12, vertical: 10),
               child: Row(
                 children: [
                   RotationTransition(
@@ -93,17 +97,16 @@ class _ExpandableCardState extends State<ExpandableCard>
               ),
             ),
           ),
+          // Lazy animated expand: only build child once ever expanded
+          if (_hasBeenExpanded)
             ClipRect(
-            child: AnimatedCrossFade(
+              child: SizeTransition(
-              firstChild: const SizedBox.shrink(),
+                sizeFactor: _controller,
-              secondChild: Padding(
+                axisAlignment: -1.0,
+                child: Padding(
                   padding: const EdgeInsets.fromLTRB(12, 0, 12, 12),
                   child: widget.child,
                 ),
-              crossFadeState: _expanded
-                  ? CrossFadeState.showSecond
-                  : CrossFadeState.showFirst,
-              duration: const Duration(milliseconds: 200),
               ),
             ),
         ],

lib/widgets/navigation/app_shell.dart

@@ -39,24 +39,18 @@ class _AppShellState extends State<AppShell> {
           hasSession: hasSession,
         ),
         Expanded(
-          child: _buildScreen(),
+          child: IndexedStack(
+            index: _screen.index,
+            children: [
+              HomeScreen(onSessionLoaded: _onSessionLoaded),
+              const TimelineScreen(),
+              const AgentsScreen(),
+              const ToolbeltScreen(),
+              const TokensScreen(),
+            ],
+          ),
         ),
       ],
     );
   }
-
-  Widget _buildScreen() {
-    switch (_screen) {
-      case SidebarScreen.home:
-        return HomeScreen(onSessionLoaded: _onSessionLoaded);
-      case SidebarScreen.timeline:
-        return const TimelineScreen();
-      case SidebarScreen.agents:
-        return const AgentsScreen();
-      case SidebarScreen.toolbelt:
-        return const ToolbeltScreen();
-      case SidebarScreen.tokens:
-        return const TokensScreen();
-    }
-  }
 }

macos/Runner.xcodeproj/project.pbxproj

@@ -671,7 +671,7 @@
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
 				CLANG_WARN_RANGE_LOOP_ANALYSIS = YES;
 				CLANG_WARN_SUSPICIOUS_MOVE = YES;
-				CODE_SIGN_IDENTITY = "-";
+				CODE_SIGN_IDENTITY = "Developer ID Application";
 				COPY_PHASE_STRIP = NO;
 				DEAD_CODE_STRIPPING = YES;
 				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
@@ -720,7 +720,11 @@
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				CLANG_ENABLE_MODULES = YES;
 				CODE_SIGN_ENTITLEMENTS = Runner/Release.entitlements;
-				CODE_SIGN_STYLE = Automatic;
+				CODE_SIGN_IDENTITY = "Developer ID Application";
+				CODE_SIGN_STYLE = Manual;
+				"DEVELOPMENT_TEAM[sdk=macosx*]" = LD76P8L42W;
+				ENABLE_HARDENED_RUNTIME = YES;
+				OTHER_CODE_SIGN_FLAGS = "--timestamp --options runtime";
 				COMBINE_HIDPI_IMAGES = YES;
 				INFOPLIST_FILE = Runner/Info.plist;
 				LD_RUNPATH_SEARCH_PATHS = (

macos/Runner/Configs/AppInfo.xcconfig

@@ -5,10 +5,10 @@
 // 'flutter create' template.
 
 // The application's name. By default this is also the title of the Flutter window.
-PRODUCT_NAME = Claude Session Analysis
+PRODUCT_NAME = Claude Session Viewer
 
 // The application's bundle identifier
-PRODUCT_BUNDLE_IDENTIFIER = com.svrnty.claudeSessionAnalysis
+PRODUCT_BUNDLE_IDENTIFIER = com.svrnty.claude-session-viewer
 
 // The copyright displayed in application information
 PRODUCT_COPYRIGHT = Copyright © 2026 Svrnty. All rights reserved.