refactor(flutter): 메일 화면의 불러오기 상태 위젯을 shared 로 옮긴다

업데이트 내역(설정 모듈)도 같은 상태 틀을 쓰는데 모듈끼리 import 하지 않으므로 shared/widgets/load_states.dart 로 옮겼다.
모양 · 동작은 그대로다(MailStateLayout → StateLayout · MailListError → LoadErrorView · 막대 SkeletonBar · LoadingSkeleton). 메일 줄 꼴의 막대와 빈 메일함 등은 메일에 남는다.

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

flutter/lib/features/mail/presentation/mail_texts.dart

@@ -11,6 +11,7 @@ import 'package:arasystem_app/core/utils/korean_text.dart';
 import 'package:arasystem_app/features/mail/data/models/mailbox.dart';
 import 'package:arasystem_app/features/mail/domain/mail_body_notices.dart';
 import 'package:arasystem_app/features/mail/domain/search_conditions.dart';
+import 'package:arasystem_app/shared/widgets/load_state_texts.dart';
 
 /// 쓰기 화면 (보드 `App1Compose`). 보드에 없는 상태(불러오기 · 받지 못함 · 칸 안내 · 첨부 상태 · 나가기 확인 · 보낸 뒤 알림)의 글은
 /// 웹 상수(`frontend/src/shared/constants/mail.ts` · `mail-send-later.ts` · `large-file.ts`)를 그대로 옮겼다 — 앱에서 새로 쓴 글은 그 줄에 적었다
@@ -356,12 +357,12 @@ abstract final class MailListTexts {
   /// 다음 쪽을 받는 동안 — 화면 낭독기
   static const String loadingMore = '메일을 더 불러오는 중';
 
-  // ── 받지 못함 ──
-  static const String retry = '다시 시도';
+  // ── 받지 못함 — 글은 함께 쓰는 받지 못함 틀(`shared/widgets/load_states.dart`)의 글과 같다 ──
+  static const String retry = LoadStateTexts.retry;
 
   /// 없는 메일함(주소에 남은 옛 id) — 다시 해도 같아 빠져나갈 단추를 준다
   static const String toInbox = '받은편지함으로';
-  static String traceCode(String code) => '문의 코드 $code';
+  static String traceCode(String code) => LoadStateTexts.traceCode(code);
 
   // ── 빈 메일함 ──
   /// "휴지통이 비어 있습니다"

flutter/lib/features/mail/presentation/pages/mail_list_page.dart

@@ -24,6 +24,7 @@ import 'package:arasystem_app/features/mail/presentation/widgets/mailbox_drawer.
 import 'package:arasystem_app/features/mail/presentation/widgets/message_row.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/push_offer_line.dart';
 import 'package:arasystem_app/shared/widgets/confirm_dialog.dart';
+import 'package:arasystem_app/shared/widgets/load_states.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
@@ -280,22 +281,24 @@ class _MailListBody extends StatelessWidget {
     const Widget skeleton = _SkeletonList();
     final Widget content = switch (list.status) {
       _ when boxesFailure != null => _FillViewport(
-        child: MailListError(error: boxesFailure, onRetry: onRetryMailboxes),
+        child: LoadErrorView(error: boxesFailure, onRetry: onRetryMailboxes),
       ),
       _ when unknownMailbox => _FillViewport(
-        child: MailListError(
+        child: LoadErrorView(
           error: ApiException.fromCode('RES_001'),
           onRetry: onRetry,
           onLeave: onLeave,
+          leaveLabel: MailListTexts.toInbox,
         ),
       ),
       _ when !mailboxesReady => skeleton,
       MailListStatus.loading => skeleton,
       MailListStatus.failed => _FillViewport(
-        child: MailListError(
+        child: LoadErrorView(
           error: list.error!,
           onRetry: onRetry,
           onLeave: onLeave,
+          leaveLabel: MailListTexts.toInbox,
         ),
       ),
       MailListStatus.ready when list.items.isEmpty => _FillViewport(

flutter/lib/features/mail/presentation/pages/mail_search_page.dart

@@ -22,6 +22,7 @@ import 'package:arasystem_app/features/mail/presentation/widgets/mail_search_bar
 import 'package:arasystem_app/features/mail/presentation/widgets/mail_search_conditions_sheet.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/mail_search_states.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/message_row.dart';
+import 'package:arasystem_app/shared/widgets/load_states.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
@@ -273,7 +274,7 @@ class _SearchBody extends StatelessWidget {
         final ApiException error =
             search.error ?? ApiException.fromCode('SYS_001');
         content = _FillViewport(
-          child: MailListError(
+          child: LoadErrorView(
             error: error,
             onRetry: onRetry,
             // 찾던 메일함이 그사이 지워졌으면(RES_001) 다시 해도 같다 — 전체 메일함에서 찾는다

flutter/lib/features/mail/presentation/pages/message_compose_page.dart

@@ -20,9 +20,9 @@ import 'package:arasystem_app/features/mail/presentation/providers/mail_toast_pr
 import 'package:arasystem_app/features/mail/presentation/widgets/compose_bars.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/compose_recipient_field.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/compose_sections.dart';
-import 'package:arasystem_app/features/mail/presentation/widgets/mail_list_states.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/reader_notices.dart';
 import 'package:arasystem_app/shared/widgets/confirm_dialog.dart';
+import 'package:arasystem_app/shared/widgets/load_states.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/semantics.dart';
 import 'package:flutter/services.dart';
@@ -749,7 +749,7 @@ class _ComposeError extends StatelessWidget {
         SliverFillRemaining(
           hasScrollBody: false,
           child: Center(
-            child: MailListError(
+            child: LoadErrorView(
               error: error,
               onRetry: onRetry,
               onLeave: onLeave,

flutter/lib/features/mail/presentation/pages/message_reader_page.dart

@@ -22,13 +22,13 @@ import 'package:arasystem_app/features/mail/presentation/providers/message_reade
 import 'package:arasystem_app/features/mail/presentation/providers/message_reader_state.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/mail_body_view.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/mail_compose_area.dart';
-import 'package:arasystem_app/features/mail/presentation/widgets/mail_list_states.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/mail_move_sheet.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/reader_attachments.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/reader_bars.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/reader_header.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/reader_notices.dart';
 import 'package:arasystem_app/shared/widgets/confirm_dialog.dart';
+import 'package:arasystem_app/shared/widgets/load_states.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
@@ -533,7 +533,7 @@ class _ReaderError extends StatelessWidget {
         SliverFillRemaining(
           hasScrollBody: false,
           child: Center(
-            child: MailListError(
+            child: LoadErrorView(
               error: error,
               onRetry: onRetry,
               onLeave: onLeave,

flutter/lib/features/mail/presentation/widgets/mail_list_states.dart

@@ -1,4 +1,3 @@
-import 'package:arasystem_app/core/api/api_exception.dart';
 import 'package:arasystem_app/core/theme/app_spacing.dart';
 import 'package:arasystem_app/core/theme/app_theme.dart';
 import 'package:arasystem_app/core/theme/app_typography.dart';
@@ -6,17 +5,15 @@ import 'package:arasystem_app/features/mail/data/models/mailbox.dart';
 import 'package:arasystem_app/features/mail/presentation/mail_texts.dart';
 import 'package:arasystem_app/features/mail/presentation/widgets/mailbox_icons.dart';
 import 'package:arasystem_app/shared/widgets/keep_all_text.dart';
+import 'package:arasystem_app/shared/widgets/load_states.dart';
 import 'package:flutter/material.dart';
 
-/// 문의 코드로 보이는 추적 ID 앞자리 수 — 웹 `TRACE_CODE_LENGTH` 와 같다
-const int kTraceCodeLength = 8;
+// 가운데 상태의 틀([StateLayout]) · 받지 못함([LoadErrorView]) · 뼈대 막대([SkeletonBar])는 업데이트 내역과 함께 쓰려고
+// `shared/widgets/load_states.dart` 로 옮겼다(모양 · 동작 그대로). 여기에는 메일 목록에만 쓰는 상태가 남는다.
 
 /// 처음 불러오는 동안의 뼈대 줄 수 — 휴대폰 한 화면쯤
 const int _skeletonRows = 8;
 
-/// 빈 메일함 · 받지 못함의 아래 여백 — 안내가 화면 가운데보다 조금 위에 오게(보드의 `padding-bottom: 120px`)
-const double _stateBottomSpace = 120;
-
 /// 뼈대 줄의 막대 폭 — 보낸 사람 · 제목(미리 보기 막대는 줄 폭을 다 쓴다)
 const double _skeletonWhoWidth = 0.4;
 const double _skeletonSubjectWidth = 0.8;
@@ -40,7 +37,7 @@ class MailListEmpty extends StatelessWidget {
   Widget build(BuildContext context) {
     final ThemeData theme = Theme.of(context);
     final AppExtraColors extra = theme.extension<AppExtraColors>()!;
-    return MailStateLayout(
+    return StateLayout(
       icon: mailboxIconOf(role),
       iconColor: extra.textMuted,
       iconBackground: theme.colorScheme.surfaceContainerHigh,
@@ -58,139 +55,6 @@ class MailListEmpty extends StatelessWidget {
   }
 }
 
-/// 받지 못함 — 사전 문구 · 문의 코드 · [다시 시도](없는 메일함은 [받은편지함으로] — 다시 해도 같다)
-/// (웹 `MailLoadError` 와 같은 결 — 문구는 에러 코드 사전에서만 온다). 읽기 화면도 쓴다(없는 메일은 [목록으로]),
-/// 검색 화면도 쓴다(찾던 메일함이 지워졌으면 [전체 메일함에서 찾기] — 제목은 보드 `App1SearchStates` 대로 작게)
-class MailListError extends StatelessWidget {
-  const MailListError({
-    required this.error,
-    required this.onRetry,
-    this.onLeave,
-    this.leaveLabel = MailListTexts.toInbox,
-    this.titleStyle,
-    super.key,
-  });
-
-  final ApiException error;
-  final VoidCallback onRetry;
-
-  /// 없는 메일함(`RES_001`)일 때 갈 곳 — 없으면 늘 [다시 시도]
-  final VoidCallback? onLeave;
-
-  /// [onLeave] 단추의 이름
-  final String leaveLabel;
-
-  /// 제목 글자 — 없으면 [MailStateLayout] 의 기본(목록 보드의 크기)
-  final TextStyle? titleStyle;
-
-  @override
-  Widget build(BuildContext context) {
-    final ThemeData theme = Theme.of(context);
-    final AppExtraColors extra = theme.extension<AppExtraColors>()!;
-    final VoidCallback? leave = onLeave;
-    final bool notFound = error.code == 'RES_001' && leave != null;
-    final String? trace = traceCodeOf(error.traceId);
-    return MailStateLayout(
-      icon: Icons.error_outline,
-      iconColor: theme.colorScheme.error,
-      iconBackground: theme.colorScheme.errorContainer,
-      title: error.message,
-      titleStyle: titleStyle,
-      children: <Widget>[
-        if (trace != null)
-          Text(
-            MailListTexts.traceCode(trace),
-            style: theme.textTheme.bodySmall?.copyWith(color: extra.textMuted),
-          ),
-        TextButton(
-          onPressed: notFound ? leave : onRetry,
-          child: Text(notFound ? leaveLabel : MailListTexts.retry),
-        ),
-      ],
-    );
-  }
-}
-
-/// 추적 ID → 화면의 문의 코드(앞 8자리). 없으면 null
-String? traceCodeOf(String? traceId) {
-  final String? value = traceId?.trim();
-  if (value == null || value.isEmpty) return null;
-  return value.length > kTraceCodeLength
-      ? value.substring(0, kTraceCodeLength)
-      : value;
-}
-
-/// 가운데 상태 화면의 틀 — 아이콘 원(72) · 제목(머리) · 그 아래 글 · 단추. 화면 가운데보다 조금 위에 온다.
-/// 목록의 빈 메일함 · 받지 못함, 검색의 결과 없음 · 아직 못 찾음 · 찾을 말이 너무 많음이 쓴다
-class MailStateLayout extends StatelessWidget {
-  const MailStateLayout({
-    required this.icon,
-    required this.iconColor,
-    required this.iconBackground,
-    required this.title,
-    required this.children,
-    this.titleStyle,
-    super.key,
-  });
-
-  final IconData icon;
-  final Color iconColor;
-  final Color iconBackground;
-  final String title;
-  final List<Widget> children;
-
-  /// 제목 글자 — 없으면 `titleMedium`(목록 보드 17 → 18). 검색 보드는 15(`titleSmall`)
-  final TextStyle? titleStyle;
-
-  @override
-  Widget build(BuildContext context) {
-    final ThemeData theme = Theme.of(context);
-    return Padding(
-      padding: const EdgeInsets.fromLTRB(
-        AppSpacing.s40,
-        0,
-        AppSpacing.s40,
-        _stateBottomSpace,
-      ),
-      child: Column(
-        mainAxisAlignment: MainAxisAlignment.center,
-        children: <Widget>[
-          ExcludeSemantics(
-            child: Container(
-              width: AppSize.stateIcon,
-              height: AppSize.stateIcon,
-              decoration: BoxDecoration(
-                shape: BoxShape.circle,
-                color: iconBackground,
-              ),
-              child: Icon(icon, size: AppSize.stateIconGlyph, color: iconColor),
-            ),
-          ),
-          const SizedBox(height: AppSpacing.s16),
-          // 여러 줄(긴 사전 문구)이어도 가운데에 — 글 자체를 가운데 맞춘다
-          DefaultTextStyle.merge(
-            textAlign: TextAlign.center,
-            child: Semantics(
-              header: true,
-              child: KeepAllText(
-                title,
-                style:
-                    titleStyle ??
-                    theme.textTheme.titleMedium?.copyWith(
-                      fontWeight: AppTypography.semiBold,
-                    ),
-              ),
-            ),
-          ),
-          const SizedBox(height: AppSpacing.s8),
-          for (final Widget child in children)
-            DefaultTextStyle.merge(textAlign: TextAlign.center, child: child),
-        ],
-      ),
-    );
-  }
-}
-
 /// 처음 불러오는 동안의 뼈대 — 줄 모양의 회색 막대(화면 낭독기는 "메일 목록 불러오는 중" — 검색은 "찾는 중")
 class MailListSkeleton extends StatelessWidget {
   const MailListSkeleton({this.label = MailListTexts.loading, super.key});
@@ -201,72 +65,52 @@ class MailListSkeleton extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final Color bar = Theme.of(context).colorScheme.surfaceContainerHighest;
-    return Semantics(
+    return LoadingSkeleton(
       label: label,
-      liveRegion: true,
-      child: ExcludeSemantics(
-        child: Column(
-          children: <Widget>[
-            for (int index = 0; index < _skeletonRows; index++)
-              Padding(
-                padding: const EdgeInsets.fromLTRB(
-                  AppSpacing.s12,
-                  AppSpacing.s14,
-                  AppSpacing.s16,
-                  AppSpacing.s14,
-                ),
-                child: Row(
-                  crossAxisAlignment: CrossAxisAlignment.start,
-                  children: <Widget>[
-                    Container(
-                      width: AppSize.avatar,
-                      height: AppSize.avatar,
-                      decoration: BoxDecoration(
-                        shape: BoxShape.circle,
-                        color: bar,
-                      ),
-                    ),
-                    const SizedBox(width: AppSpacing.s10),
-                    Expanded(
-                      child: Column(
-                        crossAxisAlignment: CrossAxisAlignment.start,
-                        children: <Widget>[
-                          FractionallySizedBox(
-                            widthFactor: _skeletonWhoWidth,
-                            child: _SkeletonBar(color: bar),
-                          ),
-                          const SizedBox(height: AppSpacing.s8),
-                          FractionallySizedBox(
-                            widthFactor: _skeletonSubjectWidth,
-                            child: _SkeletonBar(color: bar),
-                          ),
-                          const SizedBox(height: AppSpacing.s8),
-                          _SkeletonBar(color: bar),
-                        ],
-                      ),
-                    ),
-                  ],
-                ),
+      child: Column(
+        children: <Widget>[
+          for (int index = 0; index < _skeletonRows; index++)
+            Padding(
+              padding: const EdgeInsets.fromLTRB(
+                AppSpacing.s12,
+                AppSpacing.s14,
+                AppSpacing.s16,
+                AppSpacing.s14,
               ),
-          ],
-        ),
-      ),
-    );
-  }
-}
-
-class _SkeletonBar extends StatelessWidget {
-  const _SkeletonBar({required this.color});
-
-  final Color color;
-
-  @override
-  Widget build(BuildContext context) {
-    return Container(
-      height: AppSpacing.s10,
-      decoration: BoxDecoration(
-        color: color,
-        borderRadius: BorderRadius.circular(AppRadius.xs),
+              child: Row(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: <Widget>[
+                  Container(
+                    width: AppSize.avatar,
+                    height: AppSize.avatar,
+                    decoration: BoxDecoration(
+                      shape: BoxShape.circle,
+                      color: bar,
+                    ),
+                  ),
+                  const SizedBox(width: AppSpacing.s10),
+                  Expanded(
+                    child: Column(
+                      crossAxisAlignment: CrossAxisAlignment.start,
+                      children: <Widget>[
+                        FractionallySizedBox(
+                          widthFactor: _skeletonWhoWidth,
+                          child: SkeletonBar(color: bar),
+                        ),
+                        const SizedBox(height: AppSpacing.s8),
+                        FractionallySizedBox(
+                          widthFactor: _skeletonSubjectWidth,
+                          child: SkeletonBar(color: bar),
+                        ),
+                        const SizedBox(height: AppSpacing.s8),
+                        SkeletonBar(color: bar),
+                      ],
+                    ),
+                  ),
+                ],
+              ),
+            ),
+        ],
       ),
     );
   }

flutter/lib/features/mail/presentation/widgets/mail_search_states.dart

@@ -2,12 +2,12 @@ import 'package:arasystem_app/core/theme/app_spacing.dart';
 import 'package:arasystem_app/core/theme/app_theme.dart';
 import 'package:arasystem_app/core/theme/app_typography.dart';
 import 'package:arasystem_app/features/mail/presentation/mail_texts.dart';
-import 'package:arasystem_app/features/mail/presentation/widgets/mail_list_states.dart';
 import 'package:arasystem_app/shared/widgets/keep_all_text.dart';
+import 'package:arasystem_app/shared/widgets/load_states.dart';
 import 'package:flutter/material.dart';
 
 /// 검색 화면의 상태 글 — 찾기 전 · 결과 없음 · 아직 못 찾음 · 찾을 말이 너무 많음 · 목록 끝의 [더 찾기] (보드 `App1Search` · `App1SearchStates`).
-/// 가운데 상태는 목록과 같은 틀([MailStateLayout])이고, 제목은 보드대로 15(`titleSmall`) · 도움말 13(`bodySmall`)이다
+/// 가운데 상태는 목록과 같은 틀([StateLayout] — `shared/widgets/load_states.dart`)이고, 제목은 보드대로 15(`titleSmall`) · 도움말 13(`bodySmall`)이다
 TextStyle? _stateTitleStyle(ThemeData theme) =>
     theme.textTheme.titleSmall?.copyWith(fontWeight: AppTypography.semiBold);
 
@@ -71,7 +71,7 @@ class MailSearchEmpty extends StatelessWidget {
         : query.isEmpty
         ? MailSearchTexts.emptyConditionsHint
         : MailSearchTexts.emptyHint;
-    return MailStateLayout(
+    return StateLayout(
       icon: Icons.search,
       iconColor: extra.textMuted,
       iconBackground: theme.colorScheme.surfaceContainerHigh,
@@ -114,7 +114,7 @@ class MailSearchPartial extends StatelessWidget {
   Widget build(BuildContext context) {
     final ThemeData theme = Theme.of(context);
     final AppExtraColors extra = theme.extension<AppExtraColors>()!;
-    return MailStateLayout(
+    return StateLayout(
       icon: Icons.search,
       iconColor: extra.textMuted,
       iconBackground: theme.colorScheme.surfaceContainerHigh,
@@ -139,7 +139,7 @@ class MailSearchTooManyWords extends StatelessWidget {
   Widget build(BuildContext context) {
     final ThemeData theme = Theme.of(context);
     final AppExtraColors extra = theme.extension<AppExtraColors>()!;
-    return MailStateLayout(
+    return StateLayout(
       icon: Icons.error_outline,
       iconColor: extra.textMuted,
       iconBackground: theme.colorScheme.surfaceContainerHigh,