优化：针对不同内存大小的机子做卡片预览优化

android/app/src/main/kotlin/com/petsheroai/app/MainActivity.kt

@@ -1,12 +1,43 @@
 package com.petsheroai.app
 
+import android.app.ActivityManager
+import android.content.Context
 import android.os.Bundle
 import com.facebook.FacebookSdk
 import com.facebook.LoggingBehavior
 import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugin.common.MethodChannel
 
 class MainActivity : FlutterActivity() {
 
+    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
+        super.configureFlutterEngine(flutterEngine)
+        MethodChannel(
+            flutterEngine.dartExecutor.binaryMessenger,
+            "com.petsheroai.app/device_memory",
+        ).setMethodCallHandler { call, result ->
+            if (call.method == "getTotalPhysicalMemoryBytes") {
+                try {
+                    val am = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
+                    val info = ActivityManager.MemoryInfo()
+                    am.getMemoryInfo(info)
+                    val total = info.totalMem
+                    if (total > 0L) {
+                        // 避免 MethodCodec 对大于 2^31-1 的 Long 编码不一致，统一用字符串给 Dart parse
+                        result.success(total.toString())
+                    } else {
+                        result.error("INVALID", "totalMem is 0", null)
+                    }
+                } catch (e: Exception) {
+                    result.error("READ_FAILED", e.message, null)
+                }
+            } else {
+                result.notImplemented()
+            }
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         // Facebook SDK 调试日志（SDK 已在 [PetsHeroApplication] 中初始化）

lib/core/util/device_memory_profile.dart

@@ -0,0 +1,166 @@
+import 'dart:io';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+
+/// Android MethodChannel（[MainActivity] 内 `ActivityManager.MemoryInfo.totalMem`）。
+const String kDeviceMemoryMethodChannel = 'com.petsheroai.app/device_memory';
+
+/// **仅静态封面**：物理内存 **小于** 约 **3GiB**，或 **读不到内存**。
+/// 标称 4GB 机型可见 MemTotal 多在 3.2–3.8GiB，仍走 **2 路** 预览。
+const int kMemoryTierStaticOnlyBytesThreshold = 3 * 1024 * 1024 * 1024;
+
+/// **满血 4 路解码**：物理内存不少于约 **6GiB**；\[3GiB, 6GiB) 为 **2** 路。
+const int kMemoryTierFullConcurrentBytesThreshold = 6 * 1024 * 1024 * 1024;
+
+const MethodChannel _deviceMemoryChannel =
+    MethodChannel(kDeviceMemoryMethodChannel);
+
+enum _GridVideoMemoryPolicy {
+  staticOnly,
+  maxConcurrent2,
+  maxConcurrent4,
+}
+
+_GridVideoMemoryPolicy? _cachedPolicy;
+
+/// 初始化完成前：与「读不到内存」一致，仅静态（须在 [main] 中先 await [ensureDeviceMemoryProfileInitialized]）。
+_GridVideoMemoryPolicy get _effectivePolicy =>
+    _cachedPolicy ?? _GridVideoMemoryPolicy.staticOnly;
+
+/// 须在 [main] 里 `WidgetsFlutterBinding.ensureInitialized()` 之后、`runApp` 之前调用一次。
+Future<void> ensureDeviceMemoryProfileInitialized() async {
+  if (_cachedPolicy != null) return;
+  if (!Platform.isAndroid) {
+    _cachedPolicy = _GridVideoMemoryPolicy.maxConcurrent4;
+    return;
+  }
+  try {
+    final raw =
+        await _deviceMemoryChannel.invokeMethod<dynamic>(
+          'getTotalPhysicalMemoryBytes',
+        );
+    final bytes = _coerceToPhysicalRamBytes(raw);
+    if (bytes != null && _isPlausibleDeviceRamBytes(bytes)) {
+      _cachedPolicy = _policyFromTotalBytes(bytes);
+      debugPrint(
+        'DeviceMemory: totalMem≈${(bytes / (1024 * 1024)).toStringAsFixed(0)}MiB '
+        '→ $_cachedPolicy',
+      );
+      return;
+    }
+    if (bytes != null) {
+      debugPrint(
+        'DeviceMemory: rejected implausible totalMem=$bytes (channel raw=$raw)',
+      );
+    }
+  } on MissingPluginException catch (e, st) {
+    debugPrint('DeviceMemory: channel missing (embedder/tests?): $e\n$st');
+  } on PlatformException catch (e, st) {
+    debugPrint(
+      'DeviceMemory: platform ${e.code} ${e.message}\n${e.details}\n$st',
+    );
+  } on Object catch (e, st) {
+    debugPrint('DeviceMemory: channel error: $e\n$st');
+  }
+
+  try {
+    final kb = _tryParseProcMemTotalKb();
+    if (kb != null) {
+      final bytes = kb * 1024;
+      if (_isPlausibleDeviceRamBytes(bytes)) {
+        _cachedPolicy = _policyFromTotalBytes(bytes);
+        debugPrint(
+          'DeviceMemory: /proc/meminfo MemTotal=${kb}kB '
+          '→ $_cachedPolicy',
+        );
+        return;
+      }
+      debugPrint(
+        'DeviceMemory: MemTotal kB=$kb implausible as bytes=$bytes',
+      );
+    }
+  } on Object catch (e, st) {
+    debugPrint('DeviceMemory: /proc/meminfo fallback error: $e\n$st');
+  }
+
+  // 双通道均失败：与「读不到内存」一致，仅静态封面
+  debugPrint('DeviceMemory: unreadable → staticOnly (fallback)');
+  _cachedPolicy = _GridVideoMemoryPolicy.staticOnly;
+}
+
+_GridVideoMemoryPolicy _policyFromTotalBytes(int bytes) {
+  if (bytes < kMemoryTierStaticOnlyBytesThreshold) {
+    return _GridVideoMemoryPolicy.staticOnly;
+  }
+  if (bytes < kMemoryTierFullConcurrentBytesThreshold) {
+    return _GridVideoMemoryPolicy.maxConcurrent2;
+  }
+  return _GridVideoMemoryPolicy.maxConcurrent4;
+}
+
+/// 是否在网格中禁用视频预览（仅封面）。
+bool get deviceGridStaticPreviewOnly =>
+    _effectivePolicy == _GridVideoMemoryPolicy.staticOnly;
+
+/// 网格同时解码上限。
+int get deviceGridMaxConcurrentVideos {
+  switch (_effectivePolicy) {
+    case _GridVideoMemoryPolicy.staticOnly:
+      return 0;
+    case _GridVideoMemoryPolicy.maxConcurrent2:
+      return 2;
+    case _GridVideoMemoryPolicy.maxConcurrent4:
+      return 4;
+  }
+}
+
+/// Native 侧现为 **十进制字符串**（避免 Long 跨通道精度问题），仍兼容 int/double。
+int? _coerceToPhysicalRamBytes(Object? raw) {
+  if (raw == null) return null;
+  if (raw is int) return raw > 0 ? raw : null;
+  if (raw is num) {
+    final v = raw.round();
+    if (v <= 0 || !v.isFinite) return null;
+    return v.toInt();
+  }
+  final s = raw.toString().trim();
+  if (s.isEmpty) return null;
+  return int.tryParse(s);
+}
+
+bool _isPlausibleDeviceRamBytes(int bytes) {
+  const minBytes = 128 * 1024 * 1024;
+  const maxBytes = 32 * 1024 * 1024 * 1024;
+  return bytes >= minBytes && bytes <= maxBytes;
+}
+
+/// `/proc/meminfo` 的 MemTotal（kB）；不可读或异常时返回 `null`。
+int? _tryParseProcMemTotalKb() {
+  if (!Platform.isAndroid) return null;
+  try {
+    final file = File('/proc/meminfo');
+    // 部分环境下 existsSync 不可靠，直接读并由异常兜底
+    final content = file.readAsStringSync();
+    if (content.isEmpty) return null;
+    final match = RegExp(
+      r'^MemTotal:\s+(\d+)\s+kB',
+      multiLine: true,
+    ).firstMatch(content);
+    if (match == null) return null;
+    final kb = int.tryParse(match.group(1)!);
+    if (kb == null || kb <= 0) return null;
+    if (kb > 1 << 28) return null;
+    return kb;
+  } on FileSystemException catch (e, st) {
+    debugPrint('DeviceMemory: meminfo FileSystemException: $e\n$st');
+    return null;
+  } on IOException catch (e, st) {
+    debugPrint('DeviceMemory: meminfo IOException: $e\n$st');
+  } on FormatException catch (e, st) {
+    debugPrint('DeviceMemory: meminfo FormatException: $e\n$st');
+  } on Object catch (e, st) {
+    debugPrint('DeviceMemory: meminfo: $e\n$st');
+  }
+  return null;
+}

lib/features/gallery/gallery_screen.dart

@@ -11,6 +11,7 @@ import '../../core/api/services/image_api.dart';
 import '../../core/auth/auth_service.dart';
 import '../../core/theme/app_colors.dart';
 import '../../core/theme/app_spacing.dart';
+import '../../core/util/device_memory_profile.dart';
 import '../../shared/widgets/top_nav_bar.dart';
 import '../home/widgets/video_card.dart';
 
@@ -128,8 +129,7 @@ class _GalleryScreenState extends State<GalleryScreen> {
 
   /// 略低于首页：网格边缘格子可见但比例偏低时也应计入「在屏」
   static const double _videoVisibilityThreshold = 0.08;
-  /// 可见格子按曝光比例排序，同时最多自动播放 [_maxConcurrentGalleryVideos] 路；滑出后 [VideoCard] 释放解码器
+  /// 可见格子按曝光比例排序，同时最多自动播放 [deviceGridMaxConcurrentVideos] 路；滑出后 [VideoCard] 释放解码器
-  static const int _maxConcurrentGalleryVideos = 4;
   Set<int> _visibleVideoIndices = {};
   final Set<int> _userPausedVideoIndices = {};
   final Map<int, double> _cardVisibleFraction = {};
@@ -228,7 +228,7 @@ class _GalleryScreenState extends State<GalleryScreen> {
     }
     scored.sort((a, b) => b.value.compareTo(a.value));
     final next = scored
-        .take(_maxConcurrentGalleryVideos)
+        .take(deviceGridMaxConcurrentVideos)
         .map((e) => e.key)
         .toSet();
     _userPausedVideoIndices.removeWhere((i) => !next.contains(i));
@@ -527,7 +527,8 @@ class _GalleryScreenState extends State<GalleryScreen> {
                                             final coverSpecs =
                                                 _galleryCardCover(media);
                                             final videoUrl = media.videoUrl;
-                                            final hasVideo = videoUrl != null &&
+                                            final hasVideo = !deviceGridStaticPreviewOnly &&
+                                                videoUrl != null &&
                                                 videoUrl.isNotEmpty;
                                             final detectorKey =
                                                 'gallery_${index}_${videoUrl ?? media.imageUrl ?? ''}';

lib/features/home/home_screen.dart

@@ -3,6 +3,7 @@ import 'package:visibility_detector/visibility_detector.dart';
 
 import '../../core/api/services/image_api.dart';
 import '../../core/auth/auth_service.dart';
+import '../../core/util/device_memory_profile.dart';
 import '../../core/user/account_refresh.dart';
 import '../../core/user/user_state.dart';
 import '../../core/theme/app_spacing.dart';
@@ -102,7 +103,9 @@ class _HomeScreenState extends State<HomeScreen> with WidgetsBindingObserver {
     final tasks = _displayTasks;
     if (tasks.isEmpty) return;
     final seed = <int>{};
-    for (var i = 0; i < tasks.length && seed.length < _maxConcurrentHomeVideos; i++) {
+    for (var i = 0;
+        i < tasks.length && seed.length < deviceGridMaxConcurrentVideos;
+        i++) {
       final u = tasks[i].previewVideoUrl;
       if (u != null && u.isNotEmpty) seed.add(i);
     }
@@ -150,8 +153,7 @@ class _HomeScreenState extends State<HomeScreen> with WidgetsBindingObserver {
 
   /// 与 Gallery 一致：边缘格子可见比例偏低时也应参与自动播
   static const double _videoVisibilityThreshold = 0.08;
-  /// 可见格子按曝光比例排序，同时最多 [_maxConcurrentHomeVideos] 路；滑出后 [VideoCard] 释放解码器
+  /// 可见格子按曝光比例排序，同时最多 [deviceGridMaxConcurrentVideos] 路；滑出后 [VideoCard] 释放解码器
-  static const int _maxConcurrentHomeVideos = 4;
 
   void _onGridCardVisibilityChanged(int index, VisibilityInfo info) {
     if (!mounted || !widget.isActive) return;
@@ -194,7 +196,7 @@ class _HomeScreenState extends State<HomeScreen> with WidgetsBindingObserver {
 
     scored.sort((a, b) => b.value.compareTo(a.value));
     final next = scored
-        .take(_maxConcurrentHomeVideos)
+        .take(deviceGridMaxConcurrentVideos)
         .map((e) => e.key)
         .toSet();
     _userPausedVideoIndices.removeWhere((i) => !next.contains(i));
@@ -451,8 +453,11 @@ class _HomeScreenState extends State<HomeScreen> with WidgetsBindingObserver {
                               final credits = task.credits480p != null
                                   ? task.credits480p.toString()
                                   : '50';
+                              final effectiveVideoUrl = deviceGridStaticPreviewOnly
+                                  ? null
+                                  : task.previewVideoUrl;
                               final detectorKey =
-                                  'home_card_${index}_${task.previewVideoUrl ?? ''}_${task.title}';
+                                  'home_card_${index}_${effectiveVideoUrl ?? ''}_${task.title}';
                               return VisibilityDetector(
                                 key: ValueKey(detectorKey),
                                 onVisibilityChanged: (info) =>
@@ -461,7 +466,7 @@ class _HomeScreenState extends State<HomeScreen> with WidgetsBindingObserver {
                                   key: ValueKey(detectorKey),
                                   imageUrl: task.previewImageUrl ??
                                       _placeholderImage,
-                                  videoUrl: task.previewVideoUrl,
+                                  videoUrl: effectiveVideoUrl,
                                   credits: credits,
                                   playbackResumeListenable:
                                       homePlaybackResumeNonce,

lib/features/home/widgets/video_card.dart

@@ -188,9 +188,17 @@ class _VideoCardState extends State<VideoCard> {
     _bottomProgressFraction = null;
   }
 
+  /// [onStopRequested] 会触发父级 [setState]（如 HomeScreen）；不得在 [build] / [didUpdateWidget] 同步栈内调用。
+  void _scheduleNotifyStopRequested() {
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (!mounted) return;
+      widget.onStopRequested();
+    });
+  }
+
   Future<void> _loadAndPlay() async {
     if (widget.videoUrl == null || widget.videoUrl!.isEmpty) {
-      widget.onStopRequested();
+      _scheduleNotifyStopRequested();
       return;
     }
 
@@ -295,7 +303,7 @@ class _VideoCardState extends State<VideoCard> {
           _clearBottomProgress();
           _videoOpacityTarget = false;
         });
-        widget.onStopRequested();
+        _scheduleNotifyStopRequested();
       }
     }
   }

lib/main.dart

@@ -9,12 +9,14 @@ import 'app.dart';
 import 'core/api/api_config.dart';
 import 'core/auth/auth_service.dart';
 import 'core/log/app_logger.dart';
+import 'core/util/device_memory_profile.dart';
 import 'core/referrer/referrer_service.dart';
 import 'core/theme/app_colors.dart';
 import 'features/recharge/google_play_purchase_service.dart';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
+  await ensureDeviceMemoryProfileInitialized();
   _initAdjust();
   // 勿在此 await ReferrerService.init()：会阻塞首帧（Adjust 最长可达十余秒）。[AuthService.init] 内已 await getReferrer()
   SystemChrome.setSystemUIOverlayStyle(