offline updates and playhead fix

lib/debug/log_store.dart

@@ -0,0 +1,64 @@
+import 'package:flutter/foundation.dart';
+
+/// Severity of a captured log line, used only to tint it in the Debug tab.
+enum LogLevel { info, error }
+
+/// A single captured console line, stamped with the wall-clock time it arrived.
+@immutable
+class LogEntry {
+  const LogEntry(this.time, this.text, this.level);
+
+  final DateTime time;
+  final String text;
+  final LogLevel level;
+
+  /// `HH:MM:SS.mmm` — enough resolution to correlate bursts while streaming.
+  String get timeLabel {
+    String two(int n) => n.toString().padLeft(2, '0');
+    return '${two(time.hour)}:${two(time.minute)}:${two(time.second)}'
+        '.${time.millisecond.toString().padLeft(3, '0')}';
+  }
+}
+
+/// In-memory ring buffer of console/system output, surfaced in the Debug tab so
+/// the app's logs can be read (and copied) on-device during beta testing —
+/// there's no attached debugger on a TestFlight/sideloaded build.
+///
+/// A process-wide singleton because the capture hooks (the zone `print`
+/// override and `FlutterError.onError`) are installed in `main()`, outside the
+/// widget/provider tree. The UI listens via [ListenableBuilder].
+class LogStore extends ChangeNotifier {
+  LogStore._();
+  static final LogStore instance = LogStore._();
+
+  /// Keep the tail bounded so a chatty session can't grow memory without limit.
+  static const int _maxEntries = 3000;
+
+  final List<LogEntry> _entries = <LogEntry>[];
+
+  /// Newest-last, read-only view for the UI.
+  List<LogEntry> get entries => List.unmodifiable(_entries);
+
+  int get length => _entries.length;
+
+  void add(String text, {LogLevel level = LogLevel.info}) {
+    // A single print can carry embedded newlines; split so each shows as its
+    // own row (and the timestamp lines up per line).
+    final now = DateTime.now();
+    for (final line in text.split('\n')) {
+      _entries.add(LogEntry(now, line, level));
+    }
+    final overflow = _entries.length - _maxEntries;
+    if (overflow > 0) _entries.removeRange(0, overflow);
+    notifyListeners();
+  }
+
+  void clear() {
+    _entries.clear();
+    notifyListeners();
+  }
+
+  /// The whole buffer as plain text, for copy-to-clipboard / sharing.
+  String asText() =>
+      _entries.map((e) => '${e.timeLabel}  ${e.text}').join('\n');
+}