diff --git a/docs/adr/0016-sticky-timestamp-inside-chat.md b/docs/adr/0016-sticky-timestamp-inside-chat.md
new file mode 100644
index 0000000000..3c950ec972
--- /dev/null
+++ b/docs/adr/0016-sticky-timestamp-inside-chat.md
@@ -0,0 +1,45 @@
+# 16. Sticky timestamp inside chat
+
+Date: 2024-02-07
+
+## Status
+
+Accepted
+
+## Context
+
+We need to update timestamp stick to header of Chat screen
+
+## Decision
+
+- Using [inview_notifier_list](https://pub.dev/packages/inview_notifier_list) combine with `ScrollNotification`
+- Building a `ViewPort` is `InViewNotifierList` and item `InViewNotifierWidget` to wrap each message
+- Whenever a message scroll to `ViewPort` a callback will be called to update timestamp stick to header of Chat screen
+- The condition to receive the callback is `isInViewPortCondition` to the InViewNotifierList widget. 
+This is the function that defines the area where the widgets overlap should be notified as currently in-view.
+
+```dart
+typedef bool IsInViewPortCondition(
+  double deltaTop,
+  double deltaBottom,
+  double viewPortDimension,
+);
+```
+
+- In this case, we will use `deltaTop` and `deltaBottom` to check if the message is in the view port or not.
+Because list is **reversed**, so we change `deltaTopReversed` and `deltaBottomReversed`.
+
+```dart
+bool isInViewPortCondition(deltaTopReversed, deltaBottomReversed, viewPortDimension) {
+  final stickyTimestampHeight = stickyTimestampKey.globalPaintBoundsRect?.height ?? 0;
+  return deltaTopReversed < viewPortDimension - stickyTimestampHeight &&
+      deltaBottomReversed > viewPortDimension - stickyTimestampHeight;
+}
+```
+
+- When the message is in the viewport and new timestamp is different from the previous one, 
+we will update the timestamp sticky to header of Chat screen.
+
+## Consequences
+
+- The timestamp will be updated when the message is in the viewport and new timestamp is different from the previous one.
\ No newline at end of file
diff --git a/lib/pages/chat/chat.dart b/lib/pages/chat/chat.dart
index 23b0cad035..0187d9b5ca 100644
--- a/lib/pages/chat/chat.dart
+++ b/lib/pages/chat/chat.dart
@@ -1583,14 +1583,14 @@ class ChatController extends State<Chat>
   }
 
   bool isInViewPortCondition(
-    double deltaTop,
-    double deltaBottom,
+    double deltaTopReversed,
+    double deltaBottomReversed,
     double viewPortDimension,
   ) {
     final stickyTimestampHeight =
         stickyTimestampKey.globalPaintBoundsRect?.height ?? 0;
-    return deltaTop < viewPortDimension - stickyTimestampHeight &&
-        deltaBottom > viewPortDimension - stickyTimestampHeight;
+    return deltaTopReversed < viewPortDimension - stickyTimestampHeight &&
+        deltaBottomReversed > viewPortDimension - stickyTimestampHeight;
   }
 
   void _handleHideStickyTimestamp() {