feat(stats): #10 第②层 —— 统计页按设备过滤(per-device 本地日曲线)

镜像账户级时区曲线到「按设备」:
- migration 000018 `usage_device_hourly`(每设备 UTC 小时桶,稀疏)。
- ReportUsage deviceID>0 时加 AccumulateDeviceHourly;NodeStore 接口+impl+mock。
- usage.Store.DeviceHourlyRange(JOIN devices 校验归属+解析 uuid→id);UsageCurve
  增 deviceUUID 形参:空=账户级,非空=该设备本地日曲线(分桶逻辑复用)。
- /v1/usage?device=<uuid>;客户端 account_api.usage(device)、usageProvider key 改
  记录 (days,device)、stats_page 接 statsDeviceProvider → 选设备即重取该设备曲线。
测试:per-device 曲线隔离+归属校验(A的设备不进B)、UsageCurve(deviceUUID)、
migration v18、客户端 widget(选设备→/v1/usage 带 device=)。全量 go/flutter 绿。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/lib/screens/stats_page.dart

@@ -23,7 +23,10 @@ class StatsPage extends ConsumerWidget {
   Widget build(BuildContext context, WidgetRef ref) {
     final c = context.pangolin;
     final t = ref.watch(appTextProvider);
-    final usageAsync = ref.watch(usageProvider(30));
+    // 选中设备(#10②):null=全部=账户级;否则只算该设备的本地日曲线。
+    final selDevice = ref.watch(statsDeviceProvider);
+    final usageKey = (days: 30, device: selDevice);
+    final usageAsync = ref.watch(usageProvider(usageKey));
     final usage = usageAsync.valueOrNull ?? const <UsagePoint>[];
     // 先拉数据再渲染(不闪默认 0):auth 还在读 token,或已登录但 usage 还在拉 → 整页转圈。
     // (auth 加载期 isLoggedIn=false → usage 会同步返回空,故必须并上 auth.isLoading。)
@@ -62,7 +65,7 @@ class StatsPage extends ConsumerWidget {
       color: c.accent,
       backgroundColor: c.surface,
       onRefresh: () async {
-        ref.invalidate(usageProvider(30));
+        ref.invalidate(usageProvider(usageKey));
         ref.invalidate(deviceUsageProvider(30));
         await ref.read(meProvider.notifier).refresh();
       },

client/lib/services/account_api.dart

@@ -67,9 +67,10 @@ class AccountApi {
   /// GET /v1/usage?days=N&tz_offset=M — 最近 N 天用量(默认 7,后端范围 [1,90])。
   /// 带本机时区偏移(分钟,如 UTC+8=480),服务端按「本地日」聚合 → 「今天」与本地日历一致
   /// (修「29 号却显示 28 号数据」的时区 bug)。
-  Future<List<UsagePoint>> usage({int days = 7}) async {
+  Future<List<UsagePoint>> usage({int days = 7, String? device}) async {
     final tz = DateTime.now().timeZoneOffset.inMinutes;
-    final body = await _c.getJson('/v1/usage?days=$days&tz_offset=$tz');
+    final dev = (device != null && device.isNotEmpty) ? '&device=$device' : '';
+    final body = await _c.getJson('/v1/usage?days=$days&tz_offset=$tz$dev');
     final raw = (body['points'] as List<dynamic>?) ?? const [];
     return raw.map((e) => UsagePoint.fromJson(e as Map<String, dynamic>)).toList();
   }

client/lib/state/account_providers.dart

@@ -58,9 +58,12 @@ final plansProvider = FutureProvider<List<Plan>>((ref) async {
 /// 最近 N 天用量(GET /v1/usage?days=N)。未登录返回空。
 /// autoDispose:离开统计页即销毁,重进自动重取(配合下拉刷新/连接态变化 invalidate),
 /// 根治「本月流量取一次就冻住」。后端每 60s 才更新,无需更勤刷新。
-final usageProvider = FutureProvider.autoDispose.family<List<UsagePoint>, int>((ref, days) async {
+/// 用量曲线 key:days + 可选设备 uuid(null = 全部/账户级)。
+typedef UsageKey = ({int days, String? device});
+
+final usageProvider = FutureProvider.autoDispose.family<List<UsagePoint>, UsageKey>((ref, key) async {
   if (!ref.watch(authProvider).isLoggedIn) return const [];
-  return ref.read(accountApiProvider).usage(days: days);
+  return ref.read(accountApiProvider).usage(days: key.days, device: key.device);
 });
 
 /// 最近 N 天按设备用量(GET /v1/usage/devices?days=N)。统计页设备下拉/明细用。

client/test/golden/tablet_pages_golden_test.dart

@@ -115,7 +115,7 @@ Future<void> _shoot(
         localeProvider.overrideWith((ref) => lang),
         nodesProvider.overrideWith(_FakeNodesNotifier.new),
         meProvider.overrideWith(_FakeMeNotifier.new),
-        usageProvider(30).overrideWith((ref) async => _demoUsage),
+        usageProvider((days: 30, device: null)).overrideWith((ref) async => _demoUsage),
         deviceUsageProvider(30).overrideWith((ref) async => _demoDeviceUsage),
       ],
       child: MaterialApp(

client/test/widget/stats_device_filter_test.dart

@@ -0,0 +1,87 @@
+// stats_device_filter_test.dart — #10②:统计页选设备 → /v1/usage 带 device 参数。
+import 'dart:convert';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:http/http.dart' as http;
+import 'package:http/testing.dart';
+import 'package:pangolin_vpn/l10n/strings_zh.dart';
+import 'package:pangolin_vpn/pangolin_theme.dart';
+import 'package:pangolin_vpn/screens/stats_page.dart';
+import 'package:pangolin_vpn/services/api_client.dart';
+import 'package:pangolin_vpn/services/token_store.dart';
+import 'package:pangolin_vpn/state/account_providers.dart';
+import 'package:pangolin_vpn/state/auth_provider.dart';
+
+import '../helpers/harness.dart';
+
+class _LoggedIn implements TokenStore {
+  const _LoggedIn();
+  @override
+  Future<String?> loadAccessToken() async => 'tok';
+  @override
+  Future<String?> loadRefreshToken() async => null;
+  @override
+  Future<void> saveTokens({required String access, required String refresh}) async {}
+  @override
+  Future<void> clear() async {}
+  @override
+  Future<void> markOnboarded() async {}
+  @override
+  Future<bool> isOnboarded() async => true;
+  @override
+  Future<void> saveLastEmail(String email) async {}
+  @override
+  Future<String?> loadLastEmail() async => null;
+}
+
+void main() {
+  setUpAll(disableGoogleFontsFetching);
+  const t = StringsZh();
+
+  testWidgets('选设备 → /v1/usage 带 device=<uuid>', (tester) async {
+    await tester.binding.setSurfaceSize(const Size(900, 1200));
+    addTearDown(() => tester.binding.setSurfaceSize(null));
+
+    final usageDeviceParams = <String?>[];
+    final mock = MockClient((req) async {
+      final p = req.url.path;
+      if (p == '/v1/me') {
+        return http.Response(jsonEncode({'email': 'u@e', 'plan': 'free', 'devices_used': 1, 'devices_max': 5}), 200);
+      }
+      if (p == '/v1/usage') {
+        usageDeviceParams.add(req.url.queryParameters['device']);
+        return http.Response(jsonEncode({'points': []}), 200);
+      }
+      if (p == '/v1/usage/devices') {
+        return http.Response(jsonEncode({'devices': [
+          {'uuid': 'dev-1', 'name': 'iPhone', 'platform': 'ios', 'bytes_up': 10, 'bytes_down': 20, 'minutes_used': 3},
+        ]}), 200);
+      }
+      return http.Response('{}', 200);
+    });
+
+    await tester.pumpWidget(ProviderScope(
+      overrides: [
+        tokenStoreProvider.overrideWithValue(const _LoggedIn()),
+        apiClientProvider.overrideWithValue(ApiClient(
+          baseUrl: 'http://test.local', getToken: () => 'tok', refresh: () async => false, client: mock,
+        )),
+      ],
+      child: MaterialApp(theme: PangolinTheme.light, home: const Scaffold(body: StatsPage(isWide: true))),
+    ));
+    await tester.pumpAndSettle();
+
+    // 初次:账户级,不带 device。
+    expect(usageDeviceParams.contains(null), isTrue, reason: '首拉应不带 device: $usageDeviceParams');
+
+    // 打开下拉,选 iPhone。
+    await tester.tap(find.byType(PopupMenuButton<String>));
+    await tester.pumpAndSettle();
+    await tester.tap(find.text('iPhone').last);
+    await tester.pumpAndSettle();
+
+    expect(usageDeviceParams.contains('dev-1'), isTrue, reason: '选设备后应带 device=dev-1: $usageDeviceParams');
+  });
+}