add option to show timestamps on historical messages

Defaults to off so historical messages now respect the global timestamp
setting instead of forcing a locale-based timestamp when timestamps are
disabled.

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

lib/models/irc.dart

@@ -664,6 +664,7 @@ class IRCMessage {
     Map<String, UserTwitch>? channelIdToUserTwitch,
     TimestampType timestamp = TimestampType.disabled,
     bool forceTimestamp = false,
+    bool showHistoricalTimestamps = false,
     String? currentChannelId,
   }) {
     final emoteToObject = assetsStore.emoteToObject;
@@ -674,11 +675,13 @@ class IRCMessage {
     // The span list that will be used to render the chat message
     final span = <InlineSpan>[];
 
-    // Always show timestamps on historical messages, falling back to the
-    // device's locale preference when the user has timestamps disabled.
+    // When the user has timestamps disabled globally, fall back to the device's
+    // locale preference for historical messages (opt-in via setting) and for
+    // forced contexts like previews.
     final isHistorical = tags['historical'] == '1';
     final effectiveTimestamp =
-        (timestamp == TimestampType.disabled && (isHistorical || forceTimestamp))
+        (timestamp == TimestampType.disabled &&
+                ((isHistorical && showHistoricalTimestamps) || forceTimestamp))
             ? (MediaQuery.alwaysUse24HourFormatOf(context)
                 ? TimestampType.twentyFour
                 : TimestampType.twelve)

lib/screens/channel/chat/widgets/chat_message.dart

@@ -129,7 +129,10 @@ class ChatMessage extends StatelessWidget {
                   launchExternal: chatStore.settings.launchUrlExternal,
                   timestamp: chatStore.settings.timestampType,
                   forceTimestamp: forceTimestamp,
-                  channelIdToUserTwitch: overrideChannelIdToUserTwitch ??
+                  showHistoricalTimestamps:
+                      chatStore.settings.showHistoricalTimestamps,
+                  channelIdToUserTwitch:
+                      overrideChannelIdToUserTwitch ??
                       chatStore.assetsStore.channelIdToUserTwitch,
                   currentChannelId:
                       overrideCurrentChannelId ?? chatStore.channelId,
@@ -238,7 +241,10 @@ class ChatMessage extends StatelessWidget {
                   launchExternal: chatStore.settings.launchUrlExternal,
                   timestamp: chatStore.settings.timestampType,
                   forceTimestamp: forceTimestamp,
-                  channelIdToUserTwitch: overrideChannelIdToUserTwitch ??
+                  showHistoricalTimestamps:
+                      chatStore.settings.showHistoricalTimestamps,
+                  channelIdToUserTwitch:
+                      overrideChannelIdToUserTwitch ??
                       chatStore.assetsStore.channelIdToUserTwitch,
                   currentChannelId:
                       overrideCurrentChannelId ?? chatStore.channelId,
@@ -393,10 +399,12 @@ class ChatMessage extends StatelessWidget {
                         },
                         launchExternal: chatStore.settings.launchUrlExternal,
                         timestamp: chatStore.settings.timestampType,
-                  forceTimestamp: forceTimestamp,
+                        forceTimestamp: forceTimestamp,
+                        showHistoricalTimestamps:
+                            chatStore.settings.showHistoricalTimestamps,
                         channelIdToUserTwitch:
                             overrideChannelIdToUserTwitch ??
-                                chatStore.assetsStore.channelIdToUserTwitch,
+                            chatStore.assetsStore.channelIdToUserTwitch,
                         currentChannelId:
                             overrideCurrentChannelId ?? chatStore.channelId,
                       ),
@@ -523,10 +531,12 @@ class ChatMessage extends StatelessWidget {
                           badgeScale: chatStore.settings.badgeScale,
                           launchExternal: chatStore.settings.launchUrlExternal,
                           timestamp: chatStore.settings.timestampType,
-                  forceTimestamp: forceTimestamp,
+                          forceTimestamp: forceTimestamp,
+                          showHistoricalTimestamps:
+                              chatStore.settings.showHistoricalTimestamps,
                           channelIdToUserTwitch:
                               overrideChannelIdToUserTwitch ??
-                                  chatStore.assetsStore.channelIdToUserTwitch,
+                              chatStore.assetsStore.channelIdToUserTwitch,
                           currentChannelId:
                               overrideCurrentChannelId ?? chatStore.channelId,
                         ),

lib/screens/settings/chat_settings.dart

@@ -211,6 +211,16 @@ class ChatSettings extends StatelessWidget {
             onChanged: (newValue) => settingsStore.timestampType =
                 TimestampType.values[timestampNames.indexOf(newValue)],
           ),
+          SettingsListSwitch(
+            title: 'Show timestamps on historical messages',
+            subtitle: const Text(
+              'Always show timestamps on messages loaded from chat history, '
+              'even when timestamps are disabled above.',
+            ),
+            value: settingsStore.showHistoricalTimestamps,
+            onChanged: (newValue) =>
+                settingsStore.showHistoricalTimestamps = newValue,
+          ),
           const SectionHeader('Delay'),
           SettingsListSwitch(
             title: 'Auto-sync chat delay',

lib/screens/settings/stores/settings_store.dart

@@ -127,6 +127,7 @@ abstract class _SettingsStoreBase with Store {
   static const defaultShowDeletedMessages = false;
   static const defaultShowChatMessageDividers = false;
   static const defaultTimestampType = TimestampType.disabled;
+  static const defaultShowHistoricalTimestamps = false;
 
   // Alert defaults
   static const defaultHighlightFirstTimeChatter = true;
@@ -196,6 +197,10 @@ abstract class _SettingsStoreBase with Store {
   @observable
   var timestampType = defaultTimestampType;
 
+  @JsonKey(defaultValue: defaultShowHistoricalTimestamps)
+  @observable
+  var showHistoricalTimestamps = defaultShowHistoricalTimestamps;
+
   @JsonKey(defaultValue: defaultHighlightFirstTimeChatter)
   @observable
   var highlightFirstTimeChatter = defaultHighlightFirstTimeChatter;
@@ -314,6 +319,7 @@ abstract class _SettingsStoreBase with Store {
     showDeletedMessages = defaultShowDeletedMessages;
     showChatMessageDividers = defaultShowChatMessageDividers;
     timestampType = defaultTimestampType;
+    showHistoricalTimestamps = defaultShowHistoricalTimestamps;
     highlightFirstTimeChatter = defaultHighlightFirstTimeChatter;
     showUserNotices = defaultShowUserNotices;
 

lib/screens/settings/stores/settings_store.g.dart

@@ -41,6 +41,8 @@ SettingsStore _$SettingsStoreFromJson(
         unknownValue: TimestampType.disabled,
       ) ??
       TimestampType.disabled
+  ..showHistoricalTimestamps =
+      json['showHistoricalTimestamps'] as bool? ?? false
   ..highlightFirstTimeChatter =
       json['highlightFirstTimeChatter'] as bool? ?? true
   ..showUserNotices = json['showUserNotices'] as bool? ?? true
@@ -114,6 +116,7 @@ Map<String, dynamic> _$SettingsStoreToJson(
   'showDeletedMessages': instance.showDeletedMessages,
   'showChatMessageDividers': instance.showChatMessageDividers,
   'timestampType': _$TimestampTypeEnumMap[instance.timestampType]!,
+  'showHistoricalTimestamps': instance.showHistoricalTimestamps,
   'highlightFirstTimeChatter': instance.highlightFirstTimeChatter,
   'showUserNotices': instance.showUserNotices,
   'showTwitchEmotes': instance.showTwitchEmotes,
@@ -547,6 +550,28 @@ mixin _$SettingsStore on _SettingsStoreBase, Store {
     });
   }
 
+  late final _$showHistoricalTimestampsAtom = Atom(
+    name: '_SettingsStoreBase.showHistoricalTimestamps',
+    context: context,
+  );
+
+  @override
+  bool get showHistoricalTimestamps {
+    _$showHistoricalTimestampsAtom.reportRead();
+    return super.showHistoricalTimestamps;
+  }
+
+  @override
+  set showHistoricalTimestamps(bool value) {
+    _$showHistoricalTimestampsAtom.reportWrite(
+      value,
+      super.showHistoricalTimestamps,
+      () {
+        super.showHistoricalTimestamps = value;
+      },
+    );
+  }
+
   late final _$highlightFirstTimeChatterAtom = Atom(
     name: '_SettingsStoreBase.highlightFirstTimeChatter',
     context: context,
@@ -1197,6 +1222,7 @@ fontSize: ${fontSize},
 showDeletedMessages: ${showDeletedMessages},
 showChatMessageDividers: ${showChatMessageDividers},
 timestampType: ${timestampType},
+showHistoricalTimestamps: ${showHistoricalTimestamps},
 highlightFirstTimeChatter: ${highlightFirstTimeChatter},
 showUserNotices: ${showUserNotices},
 showTwitchEmotes: ${showTwitchEmotes},