Phase 3: session-end UX overhaul + closing-grace cleanup

Promotes the customer-side chat WebSocket to active-session-scoped (driven
by a new `activeSessionProvider`) so home reflects session state in real
time without a per-screen connection. Backend now auto-completes sessions
left in `closing` after a 5-minute grace window so abandoned goodbye flows
don't leave the customer's home permanently locked.

Customer:
- New `activeSessionProvider` (replaces `unread_notifier`) — single source
  of truth for the active session + unread count; polled every 15s.
- Chat WS lifecycle moved to `main.dart` listener on activeSessionProvider.
  Chat screen joins via `connectIfNotConnected`; the new
  `refreshSessionStatus` reconciles flags from the server when re-entering
  an already-connected session (covers missed `sessionClosing`/`sessionExpired`
  WS events).
- Home filters `closing` from the "Sesi Aktif" CTA so a session pending
  goodbye doesn't block "Mulai Curhat".
- Timer-expired UX is a non-dismissible modal (Tutup / Perpanjang) instead
  of an inline bar.
- Early-end goodbye composer gets an amber "Sesi telah ditutup oleh Bestie"
  banner. Goodbye TextEditingController lifted to state so focus changes
  no longer wipe the message.
- Closure provider reset on chat_screen mount to avoid stale
  `ClosureCompleteData` from a previous session leaking into a new view.
- Chat history now lists `closing` sessions with a "Belum ditutup" badge
  that routes to the live chat (goodbye composer) instead of the transcript.

Mitra:
- Same goodbye-controller fix as customer.
- Same chat-history badge + routing for `closing` items.

Backend:
- New `EndedBy.SYSTEM_AUTO_CLOSE` constant.
- `startClosureGraceTimer` extracted in `session-timer.service.js`; wired
  in from `closure.initiateEarlyEnd`, `extension.rejectExtension`, and
  `extension.handleExtensionTimeout`. Cancelled when customer submits
  goodbye.
- Restart recovery (`restoreActiveTimers`) re-arms grace timers and stamps
  any orphaned `closing` rows with `system_auto_close`.
- `getCustomerHistory` / `getMitraHistory` include `closing` alongside
  `completed`; ordering uses `COALESCE(ended_at, created_at)`.

Removed: dead `session_active_screen.dart` (no router entry).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

client_app/lib/core/chat/active_session_notifier.dart

@@ -0,0 +1,89 @@
+import 'dart:async';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import '../api/api_client_provider.dart';
+
+part 'active_session_notifier.g.dart';
+
+/// Snapshot of the current customer's active session (if any) plus its
+/// unread-message count. Backed by `/api/client/chat/session/active-with-unread`.
+///
+/// Lives at app-scope so the home CTA, the global chat WebSocket lifecycle
+/// (see `main.dart`), and any badge consumers all share one source of truth.
+class ActiveSessionData {
+  final Map<String, dynamic>? session;
+  final int unreadCount;
+
+  const ActiveSessionData({this.session, this.unreadCount = 0});
+
+  bool get hasSession => session != null;
+  String? get sessionId => session?['id'] as String?;
+  String get mitraName =>
+      (session?['mitra_display_name'] as String?) ?? 'Bestie';
+
+  static const empty = ActiveSessionData();
+}
+
+@Riverpod(keepAlive: true)
+class ActiveSession extends _$ActiveSession {
+  Timer? _pollTimer;
+
+  @override
+  Future<ActiveSessionData> build() async {
+    ref.onDispose(_stopPolling);
+    _startPolling();
+    return await _fetch();
+  }
+
+  void _startPolling() {
+    _stopPolling();
+    _pollTimer = Timer.periodic(const Duration(seconds: 15), (_) async {
+      try {
+        final next = await _fetch();
+        state = AsyncData(next);
+      } catch (_) {
+        // Keep last known state on transient failures.
+      }
+    });
+  }
+
+  void _stopPolling() {
+    _pollTimer?.cancel();
+    _pollTimer = null;
+  }
+
+  Future<ActiveSessionData> _fetch() async {
+    final apiClient = ref.read(apiClientProvider);
+    final response = await apiClient.get('/api/client/chat/session/active-with-unread');
+    final data = response['data'];
+    if (data is Map<String, dynamic>) {
+      return ActiveSessionData(
+        session: data,
+        unreadCount: data['unread_count'] as int? ?? 0,
+      );
+    }
+    return ActiveSessionData.empty;
+  }
+
+  /// Force a fresh fetch (e.g. on resume, after pairing succeeds, after a
+  /// session ends). Updates `state` synchronously to AsyncLoading-with-prev
+  /// then to AsyncData.
+  Future<void> refresh() async {
+    try {
+      final next = await _fetch();
+      state = AsyncData(next);
+    } catch (e, st) {
+      state = AsyncError(e, st);
+    }
+  }
+
+  /// Optimistic local-only update: clear unread without a round-trip
+  /// (used after the chat screen marks messages read).
+  void markRead() {
+    final current = state.valueOrNull;
+    if (current == null || !current.hasSession) return;
+    state = AsyncData(ActiveSessionData(
+      session: current.session,
+      unreadCount: 0,
+    ));
+  }
+}

client_app/lib/core/chat/active_session_notifier.g.dart

@@ -0,0 +1,26 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'active_session_notifier.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+String _$activeSessionHash() => r'8d7dec22d94b3efc32e0401b9a82a5f712e6cc16';
+
+/// See also [ActiveSession].
+@ProviderFor(ActiveSession)
+final activeSessionProvider =
+    AsyncNotifierProvider<ActiveSession, ActiveSessionData>.internal(
+  ActiveSession.new,
+  name: r'activeSessionProvider',
+  debugGetCreateSourceHash: const bool.fromEnvironment('dart.vm.product')
+      ? null
+      : _$activeSessionHash,
+  dependencies: null,
+  allTransitiveDependencies: null,
+);
+
+typedef _$ActiveSession = AsyncNotifier<ActiveSessionData>;
+// ignore_for_file: type=lint
+// ignore_for_file: subtype_of_sealed_class, invalid_use_of_internal_member, invalid_use_of_visible_for_testing_member, deprecated_member_use_from_same_package

client_app/lib/core/chat/chat_notifier.dart

@@ -6,6 +6,7 @@ import '../api/api_client.dart';
 import '../api/api_client_provider.dart';
 import '../auth/auth_bridge.dart';
 import '../constants.dart';
+import 'active_session_notifier.dart';
 
 part 'chat_notifier.g.dart';
 
@@ -102,13 +103,64 @@ class Chat extends _$Chat {
   WebSocketChannel? _channel;
   StreamSubscription? _wsSubscription;
   Timer? _typingTimer;
+  String? _connectedSessionId;
 
   ApiClient get _apiClient => ref.read(apiClientProvider);
 
   @override
   ChatData build() => const ChatInitialData();
 
+  /// Idempotent connect: if we're already connected to [sessionId], refresh
+  /// the session status from the server (in case it transitioned to closing /
+  /// expired while we weren't watching closely) but reuse the live WS.
+  /// If we're connected to a different session, disconnect first.
+  Future<void> connectIfNotConnected(String sessionId) async {
+    // ignore: avoid_print
+    print('[CONNECT_IF_NOT] target=$sessionId existing=$_connectedSessionId state=${state.runtimeType}');
+    if (_connectedSessionId == sessionId &&
+        (state is ChatConnectedData || state is ChatConnectingData)) {
+      await refreshSessionStatus(sessionId);
+      return;
+    }
+    if (_connectedSessionId != null && _connectedSessionId != sessionId) {
+      _cleanup();
+    }
+    await connect(sessionId);
+  }
+
+  /// Re-pull session status from the server and reconcile local flags. Used
+  /// when re-entering the chat screen for a session we're already connected
+  /// to — covers the case where a `sessionClosing` / `sessionExpired` WS event
+  /// was missed (e.g. socket dropped, app backgrounded, status changed before
+  /// we connected).
+  Future<void> refreshSessionStatus(String sessionId) async {
+    final current = state;
+    // ignore: avoid_print
+    print('[REFRESH_STATUS] called sessionId=$sessionId currentState=${current.runtimeType}');
+    if (current is! ChatConnectedData) return;
+    try {
+      final info = await _apiClient.get('/api/shared/chat/$sessionId/info');
+      final data = info['data'] as Map<String, dynamic>?;
+      final status = data?['status'] as String?;
+      // ignore: avoid_print
+      print('[REFRESH_STATUS] backend status=$status');
+      if (status == SessionStatus.completed ||
+          status == SessionStatus.cancelled ||
+          status == SessionStatus.expired) {
+        state = current.copyWith(sessionExpired: true);
+        return;
+      }
+      state = current.copyWith(
+        sessionClosing: status == SessionStatus.closing,
+      );
+    } catch (e) {
+      // ignore: avoid_print
+      print('[REFRESH_STATUS] error=$e');
+    }
+  }
+
   Future<void> connect(String sessionId) async {
+    _connectedSessionId = sessionId;
     state = const ChatConnectingData();
 
     try {
@@ -174,6 +226,8 @@ class Chat extends _$Chat {
     state = const ChatInitialData();
   }
 
+  String? get connectedSessionId => _connectedSessionId;
+
   void sendMessage(String content) {
     if (state is! ChatConnectedData || _channel == null) return;
     final current = state as ChatConnectedData;
@@ -317,6 +371,9 @@ class Chat extends _$Chat {
 
       case WsMessage.sessionCompleted:
         _cleanup();
+        // Home CTA must clear immediately — backend just told us the session
+        // is gone, so refresh the shared snapshot.
+        ref.invalidate(activeSessionProvider);
         break;
 
       case WsMessage.sessionTopicUpdated:
@@ -336,5 +393,6 @@ class Chat extends _$Chat {
     _channel = null;
     _typingTimer?.cancel();
     _typingTimer = null;
+    _connectedSessionId = null;
   }
 }

client_app/lib/core/chat/chat_notifier.g.dart

@@ -6,7 +6,7 @@ part of 'chat_notifier.dart';
 // RiverpodGenerator
 // **************************************************************************
 
-String _$chatHash() => r'b704f27f25fb06bbb266f394daf05ca12f518363';
+String _$chatHash() => r'30e0aa41d2022e5bb080877e23fcb0a0c0c4b927';
 
 /// See also [Chat].
 @ProviderFor(Chat)

client_app/lib/core/chat/session_closure_notifier.dart

@@ -2,6 +2,7 @@ import 'package:dio/dio.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:riverpod_annotation/riverpod_annotation.dart';
 import '../api/api_client_provider.dart';
+import 'active_session_notifier.dart';
 
 part 'session_closure_notifier.g.dart';
 
@@ -68,10 +69,14 @@ class SessionClosure extends _$SessionClosure {
         'message': message,
       });
       state = const ClosureCompleteData();
+      // The session is now completed server-side; refresh home snapshot so the
+      // CTA returns to "Mulai Curhat" without waiting for the next poll tick.
+      ref.invalidate(activeSessionProvider);
     } on DioException catch (e) {
       final code = e.response?.data?['error']?['code'];
       if (code == 'SESSION_NOT_ACTIVE' || e.response?.statusCode == 409) {
         state = const ClosureCompleteData();
+        ref.invalidate(activeSessionProvider);
       } else {
         state = const ClosureErrorData('Gagal mengirim pesan penutup.');
       }

client_app/lib/core/chat/session_closure_notifier.g.dart

@@ -6,7 +6,7 @@ part of 'session_closure_notifier.dart';
 // RiverpodGenerator
 // **************************************************************************
 
-String _$sessionClosureHash() => r'22a7994290c3a0cc3c692a68063bdc8ffcb2bf87';
+String _$sessionClosureHash() => r'f238e4098aefdd942314a13eb3fb77ed19cd2b77';
 
 /// See also [SessionClosure].
 @ProviderFor(SessionClosure)

client_app/lib/core/chat/unread_notifier.dart

@@ -1,50 +0,0 @@
-import 'dart:async';
-import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:riverpod_annotation/riverpod_annotation.dart';
-import '../api/api_client_provider.dart';
-
-part 'unread_notifier.g.dart';
-
-@Riverpod(keepAlive: true)
-class UnreadCount extends _$UnreadCount {
-  Timer? _pollTimer;
-
-  @override
-  int build() {
-    _startPolling();
-    ref.onDispose(_stopPolling);
-    return 0;
-  }
-
-  void _startPolling() {
-    _stopPolling();
-    _fetchUnreadCount();
-    _pollTimer = Timer.periodic(const Duration(seconds: 15), (_) {
-      _fetchUnreadCount();
-    });
-  }
-
-  void _stopPolling() {
-    _pollTimer?.cancel();
-    _pollTimer = null;
-  }
-
-  Future<void> _fetchUnreadCount() async {
-    try {
-      final apiClient = ref.read(apiClientProvider);
-      final response = await apiClient.get('/api/client/chat/session/active-with-unread');
-      final data = response['data'];
-      if (data is Map<String, dynamic>) {
-        state = data['unread_count'] as int? ?? 0;
-      } else {
-        state = 0;
-      }
-    } catch (_) {}
-  }
-
-  void markRead() {
-    state = 0;
-  }
-
-  void refresh() => _fetchUnreadCount();
-}

client_app/lib/core/chat/unread_notifier.g.dart

@@ -1,24 +0,0 @@
-// GENERATED CODE - DO NOT MODIFY BY HAND
-
-part of 'unread_notifier.dart';
-
-// **************************************************************************
-// RiverpodGenerator
-// **************************************************************************
-
-String _$unreadCountHash() => r'6a0b31b86ae616177f54346392d9675f916a7bec';
-
-/// See also [UnreadCount].
-@ProviderFor(UnreadCount)
-final unreadCountProvider = NotifierProvider<UnreadCount, int>.internal(
-  UnreadCount.new,
-  name: r'unreadCountProvider',
-  debugGetCreateSourceHash:
-      const bool.fromEnvironment('dart.vm.product') ? null : _$unreadCountHash,
-  dependencies: null,
-  allTransitiveDependencies: null,
-);
-
-typedef _$UnreadCount = Notifier<int>;
-// ignore_for_file: type=lint
-// ignore_for_file: subtype_of_sealed_class, invalid_use_of_internal_member, invalid_use_of_visible_for_testing_member, deprecated_member_use_from_same_package