feat: Group and broadcast channel descriptions (#7829)

fix https://github.com/chatmail/core/issues/7766

Implementation notes:

- Descriptions are only sent with member additions, when the description
is changed, and when promoting a previously-unpromoted group, in order
not to waste bandwith.
- Descriptions are not loaded everytime a chat object is loaded, because
they are only needed for the profile. Instead, they are in their own
table, and can be loaded with their own JsonRPC call.

---------

Co-authored-by: iequidoo <117991069+iequidoo@users.noreply.github.com>

deltachat-ffi/deltachat.h

@@ -1854,15 +1854,16 @@ int             dc_remove_contact_from_chat  (dc_context_t* context, uint32_t ch
 
 
 /**
- * Set group name.
+ * Set the name of a group or broadcast channel.
  *
  * If the group is already _promoted_ (any message was sent to the group),
- * all group members are informed by a special status message that is sent automatically by this function.
+ * or if this is a brodacast channel,
+ * all members are informed by a special status message that is sent automatically by this function.
  *
  * Sends out #DC_EVENT_CHAT_MODIFIED and #DC_EVENT_MSGS_CHANGED if a status message was sent.
  *
  * @memberof dc_context_t
- * @param chat_id The chat ID to set the name for. Must be a group chat.
+ * @param chat_id The chat ID to set the name for. Must be a group chat or broadcast channel.
  * @param name New name of the group.
  * @param context The context object.
  * @return 1=success, 0=error
@@ -1889,10 +1890,11 @@ int             dc_set_chat_name             (dc_context_t* context, uint32_t ch
 int dc_set_chat_ephemeral_timer (dc_context_t* context, uint32_t chat_id, uint32_t timer);
 
 /**
- * Set group profile image.
+ * Set group or broadcast channel profile image.
  *
  * If the group is already _promoted_ (any message was sent to the group),
- * all group members are informed by a special status message that is sent automatically by this function.
+ * or if this is a brodacast channel,
+ * all members are informed by a special status message that is sent automatically by this function.
  *
  * Sends out #DC_EVENT_CHAT_MODIFIED and #DC_EVENT_MSGS_CHANGED if a status message was sent.
  *
@@ -1900,7 +1902,7 @@ int dc_set_chat_ephemeral_timer (dc_context_t* context, uint32_t chat_id, uint32
  *
  * @memberof dc_context_t
  * @param context The context object.
- * @param chat_id The chat ID to set the image for.
+ * @param chat_id The chat ID to set the image for.  Must be a group chat or broadcast channel.
  * @param image Full path of the image to use as the group image. The image will immediately be copied to the 
  *     `blobdir`; the original image will not be needed anymore.
  *      If you pass NULL here, the group image is deleted (for promoted groups, all members are informed about 

deltachat-jsonrpc/src/api.rs

@@ -1068,7 +1068,8 @@ impl CommandApi {
     /// Set group name.
     ///
     /// If the group is already _promoted_ (any message was sent to the group),
-    /// all group members are informed by a special status message that is sent automatically by this function.
+    /// or if this is a brodacast channel,
+    /// all members are informed by a special status message that is sent automatically by this function.
     ///
     /// Sends out #DC_EVENT_CHAT_MODIFIED and #DC_EVENT_MSGS_CHANGED if a status message was sent.
     async fn set_chat_name(&self, account_id: u32, chat_id: u32, new_name: String) -> Result<()> {
@@ -1076,10 +1077,39 @@ impl CommandApi {
         chat::set_chat_name(&ctx, ChatId::new(chat_id), &new_name).await
     }
 
+    /// Set group or broadcast channel description.
+    ///
+    /// If the group is already _promoted_ (any message was sent to the group),
+    /// or if this is a brodacast channel,
+    /// all members are informed by a special status message that is sent automatically by this function.
+    ///
+    /// Sends out #DC_EVENT_CHAT_MODIFIED and #DC_EVENT_MSGS_CHANGED if a status message was sent.
+    ///
+    /// See also [`Self::get_chat_description`] / `getChatDescription()`.
+    async fn set_chat_description(
+        &self,
+        account_id: u32,
+        chat_id: u32,
+        description: String,
+    ) -> Result<()> {
+        let ctx = self.get_context(account_id).await?;
+        chat::set_chat_description(&ctx, ChatId::new(chat_id), &description).await
+    }
+
+    /// Load the chat description from the database.
+    ///
+    /// UIs show this in the profile page of the chat,
+    /// it is settable by [`Self::set_chat_description`] / `setChatDescription()`.
+    async fn get_chat_description(&self, account_id: u32, chat_id: u32) -> Result<String> {
+        let ctx = self.get_context(account_id).await?;
+        chat::get_chat_description(&ctx, ChatId::new(chat_id)).await
+    }
+
     /// Set group profile image.
     ///
     /// If the group is already _promoted_ (any message was sent to the group),
-    /// all group members are informed by a special status message that is sent automatically by this function.
+    /// or if this is a brodacast channel,
+    /// all members are informed by a special status message that is sent automatically by this function.
     ///
     /// Sends out #DC_EVENT_CHAT_MODIFIED and #DC_EVENT_MSGS_CHANGED if a status message was sent.
     ///

deltachat-jsonrpc/src/api/types/message.rs

@@ -388,6 +388,7 @@ impl From<download::DownloadState> for DownloadState {
 pub enum SystemMessageType {
     Unknown,
     GroupNameChanged,
+    GroupDescriptionChanged,
     GroupImageChanged,
     MemberAddedToGroup,
     MemberRemovedFromGroup,
@@ -440,6 +441,7 @@ impl From<deltachat::mimeparser::SystemMessage> for SystemMessageType {
         match system_message_type {
             SystemMessage::Unknown => SystemMessageType::Unknown,
             SystemMessage::GroupNameChanged => SystemMessageType::GroupNameChanged,
+            SystemMessage::GroupDescriptionChanged => SystemMessageType::GroupDescriptionChanged,
             SystemMessage::GroupImageChanged => SystemMessageType::GroupImageChanged,
             SystemMessage::MemberAddedToGroup => SystemMessageType::MemberAddedToGroup,
             SystemMessage::MemberRemovedFromGroup => SystemMessageType::MemberRemovedFromGroup,

deltachat-repl/src/cmdline.rs

@@ -343,6 +343,7 @@ pub async fn cmdline(context: Context, line: &str, chat_id: &mut ChatId) -> Resu
                  addmember <contact-id>\n\
                  removemember <contact-id>\n\
                  groupname <name>\n\
+                 groupdescription <description>\n\
                  groupimage <image>\n\
                  chatinfo\n\
                  sendlocations <seconds>\n\
@@ -770,6 +771,13 @@ pub async fn cmdline(context: Context, line: &str, chat_id: &mut ChatId) -> Resu
 
             println!("Chat name set");
         }
+        "groupdescription" => {
+            ensure!(sel_chat.is_some(), "No chat selected.");
+            ensure!(!arg1.is_empty(), "Argument <description> missing.");
+            chat::set_chat_description(&context, sel_chat.as_ref().unwrap().get_id(), arg1).await?;
+
+            println!("Chat description set");
+        }
         "groupimage" => {
             ensure!(sel_chat.is_some(), "No chat selected.");
             ensure!(!arg1.is_empty(), "Argument <image> missing.");

deltachat-repl/src/main.rs

@@ -179,7 +179,7 @@ const DB_COMMANDS: [&str; 11] = [
     "housekeeping",
 ];
 
-const CHAT_COMMANDS: [&str; 39] = [
+const CHAT_COMMANDS: [&str; 40] = [
     "listchats",
     "listarchived",
     "start-realtime",
@@ -192,6 +192,7 @@ const CHAT_COMMANDS: [&str; 39] = [
     "addmember",
     "removemember",
     "groupname",
+    "groupdescription",
     "groupimage",
     "chatinfo",
     "sendlocations",

src/chat.rs

@@ -1763,10 +1763,11 @@ impl Chat {
         } else if matches!(self.typ, Chattype::Group | Chattype::OutBroadcast)
             && self.param.get_int(Param::Unpromoted).unwrap_or_default() == 1
         {
-            msg.param.set_int(Param::AttachGroupImage, 1);
+            msg.param.set_int(Param::AttachChatAvatarAndDescription, 1);
             self.param
                 .remove(Param::Unpromoted)
-                .set_i64(Param::GroupNameTimestamp, msg.timestamp_sort);
+                .set_i64(Param::GroupNameTimestamp, msg.timestamp_sort)
+                .set_i64(Param::GroupDescriptionTimestamp, msg.timestamp_sort);
             self.update_param(context).await?;
             // TODO: Remove this compat code needed because Core <= v1.143:
             // - doesn't accept synchronization of QR code tokens for unpromoted groups, so we also
@@ -2807,9 +2808,18 @@ async fn render_mime_message_and_pre_message(
 ///
 /// The caller has to interrupt SMTP loop or otherwise process new rows.
 pub(crate) async fn create_send_msg_jobs(context: &Context, msg: &mut Message) -> Result<Vec<i64>> {
-    if msg.param.get_cmd() == SystemMessage::GroupNameChanged {
+    let cmd = msg.param.get_cmd();
+    if cmd == SystemMessage::GroupNameChanged || cmd == SystemMessage::GroupDescriptionChanged {
         msg.chat_id
-            .update_timestamp(context, Param::GroupNameTimestamp, msg.timestamp_sort)
+            .update_timestamp(
+                context,
+                if cmd == SystemMessage::GroupNameChanged {
+                    Param::GroupNameTimestamp
+                } else {
+                    Param::GroupDescriptionTimestamp
+                },
+                msg.timestamp_sort,
+            )
             .await?;
     }
 
@@ -3882,9 +3892,11 @@ pub(crate) async fn add_contact_to_chat_ex(
 
     let sync_qr_code_tokens;
     if from_handshake && chat.param.get_int(Param::Unpromoted).unwrap_or_default() == 1 {
+        let smeared_time = smeared_time(context);
         chat.param
             .remove(Param::Unpromoted)
-            .set_i64(Param::GroupNameTimestamp, smeared_time(context));
+            .set_i64(Param::GroupNameTimestamp, smeared_time)
+            .set_i64(Param::GroupDescriptionTimestamp, smeared_time);
         chat.update_param(context).await?;
         sync_qr_code_tokens = true;
     } else {
@@ -4187,7 +4199,107 @@ async fn send_member_removal_msg(
     send_msg(context, chat.id, &mut msg).await
 }
 
-/// Sets group or mailing list chat name.
+/// Set group or broadcast channel description.
+///
+/// If the group is already _promoted_ (any message was sent to the group),
+/// or if this is a brodacast channel,
+/// all members are informed by a special status message that is sent automatically by this function.
+///
+/// Sends out #DC_EVENT_CHAT_MODIFIED and #DC_EVENT_MSGS_CHANGED if a status message was sent.
+///
+/// See also [`get_chat_description`]
+pub async fn set_chat_description(
+    context: &Context,
+    chat_id: ChatId,
+    new_description: &str,
+) -> Result<()> {
+    set_chat_description_ex(context, Sync, chat_id, new_description).await
+}
+
+async fn set_chat_description_ex(
+    context: &Context,
+    mut sync: sync::Sync,
+    chat_id: ChatId,
+    new_description: &str,
+) -> Result<()> {
+    let new_description = sanitize_bidi_characters(new_description.trim());
+
+    ensure!(!chat_id.is_special(), "Invalid chat ID");
+
+    let chat = Chat::load_from_db(context, chat_id).await?;
+    ensure!(
+        chat.typ == Chattype::Group || chat.typ == Chattype::OutBroadcast,
+        "Can only set description for groups / broadcasts"
+    );
+    ensure!(
+        !chat.grpid.is_empty(),
+        "Cannot set description for ad hoc groups"
+    );
+    if !chat.is_self_in_chat(context).await? {
+        context.emit_event(EventType::ErrorSelfNotInGroup(
+            "Cannot set chat description; self not in group".into(),
+        ));
+        bail!("Cannot set chat description; self not in group");
+    }
+
+    let affected_rows = context
+        .sql
+        .execute(
+            "INSERT INTO chats_descriptions(chat_id, description) VALUES(?, ?)
+            ON CONFLICT(chat_id) DO UPDATE
+            SET description=excluded.description WHERE description<>excluded.description",
+            (chat_id, &new_description),
+        )
+        .await?;
+
+    if affected_rows == 0 {
+        return Ok(());
+    }
+
+    if chat.is_promoted() {
+        let mut msg = Message::new(Viewtype::Text);
+        msg.text = stock_str::msg_chat_description_changed(context, ContactId::SELF).await;
+        msg.param.set_cmd(SystemMessage::GroupDescriptionChanged);
+
+        msg.id = send_msg(context, chat_id, &mut msg).await?;
+        context.emit_msgs_changed(chat_id, msg.id);
+        sync = Nosync;
+    }
+    context.emit_event(EventType::ChatModified(chat_id));
+
+    if sync.into() {
+        chat.sync(context, SyncAction::SetDescription(new_description))
+            .await
+            .log_err(context)
+            .ok();
+    }
+
+    Ok(())
+}
+
+/// Load the chat description from the database.
+///
+/// UIs show this in the profile page of the chat,
+/// it is settable by [`set_chat_description`]
+pub async fn get_chat_description(context: &Context, chat_id: ChatId) -> Result<String> {
+    let description = context
+        .sql
+        .query_get_value(
+            "SELECT description FROM chats_descriptions WHERE chat_id=?",
+            (chat_id,),
+        )
+        .await?
+        .unwrap_or_default();
+    Ok(description)
+}
+
+/// Sets group, mailing list, or broadcast channel chat name.
+///
+/// If the group is already _promoted_ (any message was sent to the group),
+/// or if this is a brodacast channel,
+/// all members are informed by a special status message that is sent automatically by this function.
+///
+/// Sends out #DC_EVENT_CHAT_MODIFIED and #DC_EVENT_MSGS_CHANGED if a status message was sent.
 pub async fn set_chat_name(context: &Context, chat_id: ChatId, new_name: &str) -> Result<()> {
     rename_ex(context, Sync, chat_id, new_name).await
 }
@@ -5015,6 +5127,7 @@ pub(crate) enum SyncAction {
     ///
     /// The list is a list of pairs of fingerprint and address.
     SetPgpContacts(Vec<(String, String)>),
+    SetDescription(String),
     Delete,
 }
 
@@ -5113,6 +5226,9 @@ impl Context {
                 Err(anyhow!("sync_alter_chat({id:?}, {action:?}): Bad request."))
             }
             SyncAction::Rename(to) => rename_ex(self, Nosync, chat_id, to).await,
+            SyncAction::SetDescription(to) => {
+                set_chat_description_ex(self, Nosync, chat_id, to).await
+            }
             SyncAction::SetContacts(addrs) => set_contacts_by_addrs(self, chat_id, addrs).await,
             SyncAction::SetPgpContacts(fingerprint_addrs) => {
                 set_contacts_by_fingerprints(self, chat_id, fingerprint_addrs).await

src/chat/chat_tests.rs

@@ -3156,6 +3156,119 @@ async fn test_broadcasts_name_and_avatar() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_chat_description_basic() {
+    test_chat_description("", false).await.unwrap()
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_chat_description_unpromoted_description() {
+    test_chat_description("Unpromoted description in the beginning", false)
+        .await
+        .unwrap()
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_chat_description_qr() {
+    test_chat_description("", true).await.unwrap()
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn test_chat_description_unpromoted_description_qr() {
+    test_chat_description("Unpromoted description in the beginning", true)
+        .await
+        .unwrap()
+}
+
+async fn test_chat_description(initial_description: &str, join_via_qr: bool) -> Result<()> {
+    let mut tcm = TestContextManager::new();
+    let alice = &tcm.alice().await;
+    let alice2 = &tcm.alice().await;
+    let bob = &tcm.bob().await;
+
+    alice.set_config_bool(Config::SyncMsgs, true).await?;
+    alice2.set_config_bool(Config::SyncMsgs, true).await?;
+
+    tcm.section("Create a group chat, and add Bob");
+    let alice_chat_id = create_group(alice, "My Group").await?;
+
+    if !initial_description.is_empty() {
+        set_chat_description(alice, alice_chat_id, initial_description).await?;
+    }
+    sync(alice, alice2).await;
+
+    let alice2_chat_id = get_chat_id_by_grpid(
+        alice2,
+        &Chat::load_from_db(alice, alice_chat_id).await?.grpid,
+    )
+    .await?
+    .unwrap()
+    .0;
+    assert_eq!(
+        get_chat_description(alice2, alice2_chat_id).await?,
+        initial_description
+    );
+
+    let bob_chat_id = if join_via_qr {
+        let qr = get_securejoin_qr(alice, Some(alice_chat_id)).await.unwrap();
+        tcm.exec_securejoin_qr(bob, alice, &qr).await
+    } else {
+        let alice_bob_id = alice.add_or_lookup_contact_id(bob).await;
+        add_contact_to_chat(alice, alice_chat_id, alice_bob_id).await?;
+        let sent = alice.send_text(alice_chat_id, "promoting the group").await;
+        bob.recv_msg(&sent).await.chat_id
+    };
+    assert_eq!(
+        get_chat_description(bob, bob_chat_id).await?,
+        initial_description
+    );
+
+    for description in ["This is a cool group", "", "ä ẟ 😂"] {
+        tcm.section(&format!(
+            "Alice sets the chat description to '{description}'"
+        ));
+        set_chat_description(alice, alice_chat_id, description).await?;
+        let sent = alice.pop_sent_msg().await;
+        assert_eq!(
+            sent.load_from_db().await.text,
+            "You changed the chat description."
+        );
+
+        tcm.section("Bob receives the description change");
+        let rcvd = bob.recv_msg(&sent).await;
+        assert_eq!(rcvd.get_info_type(), SystemMessage::GroupDescriptionChanged);
+        assert_eq!(rcvd.text, "Chat description changed by alice@example.org.");
+
+        assert_eq!(get_chat_description(bob, rcvd.chat_id).await?, description);
+
+        tcm.section("Check Alice's second device");
+        alice2.recv_msg(&sent).await;
+        let alice2_chat_id = get_chat_id_by_grpid(
+            alice2,
+            &Chat::load_from_db(alice, alice_chat_id).await?.grpid,
+        )
+        .await?
+        .unwrap()
+        .0;
+
+        assert_eq!(
+            get_chat_description(alice2, alice2_chat_id).await?,
+            description
+        );
+    }
+
+    tcm.section("Alice calls set_chat_description() without actually changing the description");
+    set_chat_description(alice, alice_chat_id, "ä ẟ 😂").await?;
+    assert!(
+        alice
+            .pop_sent_msg_opt(Duration::from_secs(0))
+            .await
+            .is_none()
+    );
+
+    Ok(())
+}
+
 /// Tests that directly after broadcast-securejoin,
 /// the brodacast is shown correctly on both devices.
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]

src/headerdef.rs

@@ -60,6 +60,9 @@ pub enum HeaderDef {
     ChatGroupName,
     ChatGroupNameChanged,
     ChatGroupNameTimestamp,
+    ChatGroupDescription,
+    ChatGroupDescriptionChanged,
+    ChatGroupDescriptionTimestamp,
     ChatVerified,
     ChatGroupAvatar,
     ChatUserAvatar,

src/message.rs

@@ -1005,6 +1005,7 @@ impl Message {
     pub async fn get_info_contact_id(&self, context: &Context) -> Result<Option<ContactId>> {
         match self.param.get_cmd() {
             SystemMessage::GroupNameChanged
+            | SystemMessage::GroupDescriptionChanged
             | SystemMessage::GroupImageChanged
             | SystemMessage::EphemeralTimerChanged => {
                 if self.from_id != ContactId::INFO {

src/mimefactory.rs

@@ -663,7 +663,7 @@ impl MimeFactory {
 
                 if msg
                     .param
-                    .get_bool(Param::AttachGroupImage)
+                    .get_bool(Param::AttachChatAvatarAndDescription)
                     .unwrap_or_default()
                 {
                     return chat.param.get(Param::ProfileImage).map(Into::into);
@@ -1669,6 +1669,12 @@ impl MimeFactory {
                         mail_builder::headers::text::Text::new(old_name).into(),
                     ));
                 }
+                SystemMessage::GroupDescriptionChanged => {
+                    headers.push((
+                        "Chat-Group-Description-Changed",
+                        mail_builder::headers::text::Text::new("").into(),
+                    ));
+                }
                 SystemMessage::GroupImageChanged => {
                     headers.push((
                         "Chat-Content",
@@ -1683,6 +1689,26 @@ impl MimeFactory {
                 }
                 _ => {}
             }
+
+            if command == SystemMessage::GroupDescriptionChanged
+                || command == SystemMessage::MemberAddedToGroup
+                || msg
+                    .param
+                    .get_bool(Param::AttachChatAvatarAndDescription)
+                    .unwrap_or_default()
+            {
+                let description = chat::get_chat_description(context, chat.id).await?;
+                headers.push((
+                    "Chat-Group-Description",
+                    mail_builder::headers::text::Text::new(description.clone()).into(),
+                ));
+                if let Some(ts) = chat.param.get_i64(Param::GroupDescriptionTimestamp) {
+                    headers.push((
+                        "Chat-Group-Description-Timestamp",
+                        mail_builder::headers::text::Text::new(ts.to_string()).into(),
+                    ));
+                }
+            }
         }
 
         match command {

src/mimeparser.rs

@@ -186,10 +186,10 @@ pub enum SystemMessage {
     #[default]
     Unknown = 0,
 
-    /// Group name changed.
+    /// Group or broadcast channel name changed.
     GroupNameChanged = 2,
 
-    /// Group avatar changed.
+    /// Group or broadcast channel avatar changed.
     GroupImageChanged = 3,
 
     /// Member was added to the group.
@@ -254,6 +254,9 @@ pub enum SystemMessage {
 
     /// Message indicating that a call was ended.
     CallEnded = 67,
+
+    /// Group or broadcast channel description changed.
+    GroupDescriptionChanged = 70,
 }
 
 const MIME_AC_SETUP_FILE: &str = "application/autocrypt-setup";
@@ -773,6 +776,11 @@ impl MimeMessage {
             self.is_system_message = SystemMessage::MemberAddedToGroup;
         } else if self.get_header(HeaderDef::ChatGroupNameChanged).is_some() {
             self.is_system_message = SystemMessage::GroupNameChanged;
+        } else if self
+            .get_header(HeaderDef::ChatGroupDescriptionChanged)
+            .is_some()
+        {
+            self.is_system_message = SystemMessage::GroupDescriptionChanged;
         }
     }
 

src/param.rs

@@ -140,7 +140,7 @@ pub enum Param {
     Arg4 = b'H',
 
     /// For Messages
-    AttachGroupImage = b'A',
+    AttachChatAvatarAndDescription = b'A',
 
     /// For Messages
     WebrtcRoom = b'V',
@@ -219,6 +219,9 @@ pub enum Param {
     /// For Chats: timestamp of group name update.
     GroupNameTimestamp = b'g',
 
+    /// For Chats: timestamp of chat description update.
+    GroupDescriptionTimestamp = b'6',
+
     /// For Chats: timestamp of member list update.
     MemberListTimestamp = b'k',
 

src/receive_imf.rs

@@ -8,7 +8,8 @@ use std::sync::LazyLock;
 use anyhow::{Context as _, Result, ensure};
 use data_encoding::BASE32_NOPAD;
 use deltachat_contact_tools::{
-    ContactAddress, addr_cmp, addr_normalize, may_be_valid_addr, sanitize_single_line,
+    ContactAddress, addr_cmp, addr_normalize, may_be_valid_addr, sanitize_bidi_characters,
+    sanitize_single_line,
 };
 use iroh_gossip::proto::TopicId;
 use mailparse::SingleInfo;
@@ -3101,7 +3102,7 @@ async fn apply_group_changes(
     }
 
     if is_from_in_chat {
-        apply_chat_name_and_avatar_changes(
+        apply_chat_name_avatar_and_description_changes(
             context,
             mime_parser,
             from_id,
@@ -3280,7 +3281,7 @@ async fn apply_group_changes(
 ///
 /// - `send_event_chat_modified` is set to `true` if ChatModified event should be sent
 /// - `better_msg` is filled with an info message about name change, if necessary
-async fn apply_chat_name_and_avatar_changes(
+async fn apply_chat_name_avatar_and_description_changes(
     context: &Context,
     mime_parser: &MimeMessage,
     from_id: ContactId,
@@ -3339,6 +3340,51 @@ async fn apply_chat_name_and_avatar_changes(
         }
     }
 
+    // ========== Apply chat description changes ==========
+
+    if let Some(new_description) = mime_parser
+        .get_header(HeaderDef::ChatGroupDescription)
+        .map(|d| d.trim())
+    {
+        let new_description = sanitize_bidi_characters(new_description.trim());
+        let old_description = chat::get_chat_description(context, chat.id).await?;
+
+        let old_timestamp = chat
+            .param
+            .get_i64(Param::GroupDescriptionTimestamp)
+            .unwrap_or(0);
+        let timestamp_in_header = mime_parser
+            .get_header(HeaderDef::ChatGroupDescriptionTimestamp)
+            .and_then(|s| s.parse::<i64>().ok());
+
+        let new_timestamp = timestamp_in_header.unwrap_or(mime_parser.timestamp_sent);
+        // To provide consistency, compare descriptions if timestamps are equal.
+        if (old_timestamp, &old_description) < (new_timestamp, &new_description)
+            && chat
+                .id
+                .update_timestamp(context, Param::GroupDescriptionTimestamp, new_timestamp)
+                .await?
+            && new_description != old_description
+        {
+            info!(context, "Updating description for chat {}.", chat.id);
+            context
+                .sql
+                .execute(
+                    "INSERT OR REPLACE INTO chats_descriptions(chat_id, description) VALUES(?, ?)",
+                    (chat.id, &new_description),
+                )
+                .await?;
+            *send_event_chat_modified = true;
+        }
+        if mime_parser
+            .get_header(HeaderDef::ChatGroupDescriptionChanged)
+            .is_some()
+        {
+            better_msg
+                .get_or_insert(stock_str::msg_chat_description_changed(context, from_id).await);
+        }
+    }
+
     // ========== Apply chat avatar changes ==========
 
     if let (Some(value), None) = (mime_parser.get_header(HeaderDef::ChatContent), &better_msg)
@@ -3667,7 +3713,7 @@ async fn apply_out_broadcast_changes(
     let mut better_msg = None;
 
     if from_id == ContactId::SELF {
-        apply_chat_name_and_avatar_changes(
+        apply_chat_name_avatar_and_description_changes(
             context,
             mime_parser,
             from_id,
@@ -3757,7 +3803,7 @@ async fn apply_in_broadcast_changes(
     let mut send_event_chat_modified = false;
     let mut better_msg = None;
 
-    apply_chat_name_and_avatar_changes(
+    apply_chat_name_avatar_and_description_changes(
         context,
         mime_parser,
         from_id,

src/sql/migrations.rs

@@ -1558,6 +1558,15 @@ ALTER TABLE contacts ADD COLUMN name_normalized TEXT;
         .await?;
     }
 
+    inc_and_check(&mut migration_version, 147)?;
+    if dbversion < migration_version {
+        sql.execute_migration(
+            "CREATE TABLE chats_descriptions (chat_id INTEGER PRIMARY KEY AUTOINCREMENT, description TEXT NOT NULL DEFAULT '') STRICT;",
+            migration_version,
+        )
+        .await?;
+    }
+
     let new_version = sql
         .get_raw_config_int(VERSION_CFG)
         .await?

src/stock_str.rs

@@ -423,6 +423,12 @@ https://delta.chat/donate"))]
 
     #[strum(props(fallback = "Incoming video call"))]
     IncomingVideoCall = 235,
+
+    #[strum(props(fallback = "You changed the chat description."))]
+    MsgYouChangedDescription = 240,
+
+    #[strum(props(fallback = "Chat description changed by %1$s."))]
+    MsgChatDescriptionChangedBy = 241,
 }
 
 impl StockMessage {
@@ -601,6 +607,19 @@ pub(crate) async fn msg_grp_img_changed(context: &Context, by_contact: ContactId
     }
 }
 
+pub(crate) async fn msg_chat_description_changed(
+    context: &Context,
+    by_contact: ContactId,
+) -> String {
+    if by_contact == ContactId::SELF {
+        translated(context, StockMessage::MsgYouChangedDescription).await
+    } else {
+        translated(context, StockMessage::MsgChatDescriptionChangedBy)
+            .await
+            .replace1(&by_contact.get_stock_name(context).await)
+    }
+}
+
 /// Stock string: `You added member %1$s.` or `Member %1$s added by %2$s.`.
 ///
 /// The `added_member_addr` parameter should be an email address and is looked up in the