fix: use member list timestamp

src/chat.rs

@@ -1221,6 +1221,22 @@ impl ChatId {
         Ok(self.get_param(context).await?.exists(Param::Devicetalk))
     }
 
+    /// Returns chat member list timestamp.
+    pub(crate) async fn member_list_timestamp(self, context: &Context) -> Result<i64> {
+        let creation_timestamp: i64 = context
+            .sql
+            .query_get_value("SELECT created_timestamp FROM chats WHERE id=?", (self,))
+            .await
+            .context("SQL error querying created_timestamp")?
+            .context("Chat not found")?;
+
+        Ok(self
+            .get_param(context)
+            .await?
+            .get_i64(Param::MemberListTimestamp)
+            .unwrap_or(creation_timestamp))
+    }
+
     async fn parent_query<T, F>(
         self,
         context: &Context,

src/mimefactory.rs

@@ -12,7 +12,7 @@ use tokio::fs;
 use crate::blob::BlobObject;
 use crate::chat::{self, Chat};
 use crate::config::Config;
-use crate::constants::{Chattype, DC_FROM_HANDSHAKE};
+use crate::constants::{Chattype, DC_FROM_HANDSHAKE, TIMESTAMP_SENT_TOLERANCE};
 use crate::contact::{Contact, ContactId, Origin};
 use crate::context::Context;
 use crate::e2ee::EncryptHelper;
@@ -621,7 +621,17 @@ impl MimeFactory {
             );
         }
 
-        if !self.member_timestamps.is_empty() {
+        let chat_memberlist_is_stale = if let Loaded::Message { chat, .. } = &self.loaded {
+            let now = time();
+            let member_list_ts = chat.id.member_list_timestamp(context).await?;
+            member_list_ts > 0
+                && now.saturating_add(TIMESTAMP_SENT_TOLERANCE)
+                    >= member_list_ts.saturating_add(60 * 24 * 3600)
+        } else {
+            false
+        };
+
+        if !self.member_timestamps.is_empty() && !chat_memberlist_is_stale {
             headers.push(
                 Header::new_with_value(
                     "Chat-Group-Member-Timestamps".into(),

src/param.rs

@@ -183,8 +183,6 @@ pub enum Param {
     GroupNameTimestamp = b'g',
 
     /// For Chats: timestamp of member list update.
-    ///
-    /// Deprecated 2025-01-07.
     MemberListTimestamp = b'k',
 
     /// For Webxdc Message Instances: Current document name

src/receive_imf.rs

@@ -2395,6 +2395,14 @@ async fn apply_group_changes(
                 send_event_chat_modified = true;
             }
         }
+
+        chat_id
+            .update_timestamp(
+                context,
+                Param::MemberListTimestamp,
+                mime_parser.timestamp_sent,
+            )
+            .await?;
     }
 
     if let Some(added_id) = added_id {