Window comes back at its last size, position and maximized state

Saved on resize, move, maximize and close; on start (and hot restart)
the normal size and maximized state come back everywhere, the position
on Windows and X11 when it still lands on a display (Wayland places
windows itself).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/desktop/lib/src/platform/window_memory.dart

@@ -0,0 +1,106 @@
+import 'dart:async';
+import 'dart:io';
+import 'dart:ui';
+
+import 'package:flutter/foundation.dart';
+import 'package:hive_ce_flutter/hive_flutter.dart';
+import 'package:screen_retriever/screen_retriever.dart';
+import 'package:window_manager/window_manager.dart';
+
+/// The window's size, position and maximized state across restarts (and
+/// hot restarts), in the settings box. The size and position kept are
+/// the normal (unmaximized) ones; fullscreen is never saved or restored.
+/// Wayland lets no app place its own window, so there only the size and
+/// maximized state come back (the compositor decides the position).
+class WindowMemory with WindowListener {
+  static const _key = 'windowBounds';
+  static const defaultSize = Size(1280, 720);
+
+  // Null when the settings box failed to open: defaults, nothing saved.
+  final Box? _box;
+  Timer? _save;
+  WindowMemory(this._box);
+
+  static bool get _canPlace => !(Platform.isLinux && Platform.environment['WAYLAND_DISPLAY'] != null);
+
+  Map? get _saved => _box?.get(_key) is Map ? _box!.get(_key) as Map : null;
+
+  /// The size to open at: the last normal size, else [defaultSize].
+  Size get size {
+    final s = _saved;
+    final w = s?['w'], h = s?['h'];
+    return w is num && h is num && w >= 160 && h >= 90 ? Size(w.toDouble(), h.toDouble()) : defaultSize;
+  }
+
+  /// Whether a saved position exists to place the window at (else center).
+  bool get hasPosition => _canPlace && _saved?['x'] is num && _saved?['y'] is num;
+
+  /// After the window shows: back to the saved position when it still
+  /// lands on a connected display, maximized when it was; then listens.
+  Future<void> restore() async {
+    final s = _saved;
+    try {
+      if (s != null && hasPosition) {
+        final rect = Offset((s['x'] as num).toDouble(), (s['y'] as num).toDouble()) & size;
+        if (await _onSomeDisplay(rect)) {
+          await windowManager.setPosition(rect.topLeft);
+        } else {
+          await windowManager.center();
+        }
+      }
+      if (s?['max'] == true) await windowManager.maximize();
+    } catch (e) {
+      debugPrint('window restore failed: $e');
+    }
+    windowManager.addListener(this);
+  }
+
+  // At least a 100×50 corner of the title area on a display's visible area.
+  static Future<bool> _onSomeDisplay(Rect r) async {
+    final grip = Rect.fromLTWH(r.left, r.top, r.width.clamp(0, 100).toDouble(), 50);
+    for (final d in await screenRetriever.getAllDisplays()) {
+      final area = (d.visiblePosition ?? Offset.zero) & (d.visibleSize ?? d.size);
+      if (area.overlaps(grip)) return true;
+    }
+    return false;
+  }
+
+  void _later() {
+    _save?.cancel();
+    _save = Timer(const Duration(milliseconds: 400), () => unawaited(save()));
+  }
+
+  /// Writes the current state now (also on close).
+  Future<void> save() async {
+    _save?.cancel();
+    final box = _box;
+    if (box == null) return;
+    try {
+      if (await windowManager.isFullScreen() || await windowManager.isMinimized()) return;
+      final max = await windowManager.isMaximized();
+      final s = Map<String, Object?>.of((_saved ?? const {}).cast<String, Object?>());
+      s['max'] = max;
+      if (!max) {
+        final b = await windowManager.getBounds();
+        s['w'] = b.width;
+        s['h'] = b.height;
+        if (_canPlace) {
+          s['x'] = b.left;
+          s['y'] = b.top;
+        }
+      }
+      await box.put(_key, s);
+    } catch (e) {
+      debugPrint('window save failed: $e');
+    }
+  }
+
+  @override
+  void onWindowResized() => _later();
+  @override
+  void onWindowMoved() => _later();
+  @override
+  void onWindowMaximize() => _later();
+  @override
+  void onWindowUnmaximize() => _later();
+}