Live group update messages on conversation list and conversation.

app/build.gradle

@@ -359,10 +359,10 @@ dependencies {
     testImplementation 'junit:junit:4.12'
     testImplementation 'org.assertj:assertj-core:3.11.1'
     testImplementation 'org.mockito:mockito-core:1.9.5'
-    testImplementation 'org.powermock:powermock-api-mockito:1.6.1'
+    testImplementation 'org.powermock:powermock-api-mockito:1.6.5'
-    testImplementation 'org.powermock:powermock-module-junit4:1.6.1'
+    testImplementation 'org.powermock:powermock-module-junit4:1.6.5'
-    testImplementation 'org.powermock:powermock-module-junit4-rule:1.6.1'
+    testImplementation 'org.powermock:powermock-module-junit4-rule:1.6.5'
-    testImplementation 'org.powermock:powermock-classloading-xstream:1.6.1'
+    testImplementation 'org.powermock:powermock-classloading-xstream:1.6.5'
 
     testImplementation 'androidx.test:core:1.2.0'
     testImplementation ('org.robolectric:robolectric:4.2') {

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationUpdateItem.java

@@ -4,6 +4,7 @@ import android.content.Context;
 import android.graphics.ColorFilter;
 import android.graphics.PorterDuff;
 import android.graphics.PorterDuffColorFilter;
+import android.text.SpannableString;
 import android.util.AttributeSet;
 import android.view.View;
 import android.widget.ImageView;
@@ -13,31 +14,39 @@ import android.widget.TextView;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.core.content.ContextCompat;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.Observer;
+import androidx.lifecycle.Transformations;
 
 import org.thoughtcrime.securesms.BindableConversationItem;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.VerifyIdentityActivity;
 import org.thoughtcrime.securesms.database.IdentityDatabase.IdentityRecord;
+import org.thoughtcrime.securesms.database.model.LiveUpdateMessage;
 import org.thoughtcrime.securesms.database.model.MessageRecord;
+import org.thoughtcrime.securesms.database.model.UpdateDescription;
 import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.mms.GlideRequests;
 import org.thoughtcrime.securesms.recipients.LiveRecipient;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientForeverObserver;
 import org.thoughtcrime.securesms.util.DateUtils;
+import org.thoughtcrime.securesms.util.Debouncer;
 import org.thoughtcrime.securesms.util.ExpirationUtil;
-import org.thoughtcrime.securesms.util.GroupUtil;
 import org.thoughtcrime.securesms.util.IdentityUtil;
 import org.thoughtcrime.securesms.util.ThemeUtil;
 import org.thoughtcrime.securesms.util.concurrent.ListenableFuture;
 import org.whispersystems.libsignal.util.guava.Optional;
 
 import java.util.Locale;
+import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.ExecutionException;
 
-public class ConversationUpdateItem extends LinearLayout
+public final class ConversationUpdateItem extends LinearLayout
-    implements RecipientForeverObserver, BindableConversationItem
+                                          implements RecipientForeverObserver,
+                                                     BindableConversationItem,
+                                                     Observer<SpannableString>
 {
   private static final String TAG = ConversationUpdateItem.class.getSimpleName();
 
@@ -50,6 +59,9 @@ public class ConversationUpdateItem extends LinearLayout
   private LiveRecipient             sender;
   private MessageRecord             messageRecord;
   private Locale                    locale;
+  private LiveData<SpannableString> displayBody;
+
+  private final Debouncer bodyClearDebouncer = new Debouncer(150);
 
   public ConversationUpdateItem(Context context) {
     super(context);
@@ -108,9 +120,8 @@ public class ConversationUpdateItem extends LinearLayout
       this.sender.removeForeverObserver(this);
     }
 
-    if (this.messageRecord != null && messageRecord.isGroupAction()) {
+    observeDisplayBody(null);
-      GroupUtil.getDescription(getContext(), messageRecord.getBody(), messageRecord.isGroupV2()).removeObserver(this);
+    setBodyText(null);
-    }
 
     this.messageRecord = messageRecord;
     this.sender        = messageRecord.getIndividualRecipient().live();
@@ -118,23 +129,49 @@ public class ConversationUpdateItem extends LinearLayout
 
     this.sender.observeForever(this);
 
-    if (this.messageRecord != null && messageRecord.isGroupAction()) {
+    UpdateDescription         updateDescription      = Objects.requireNonNull(messageRecord.getUpdateDisplayBody(getContext()));
-      GroupUtil.getDescription(getContext(), messageRecord.getBody(), messageRecord.isGroupV2()).addObserver(this);
+    LiveData<String>          liveUpdateMessage      = LiveUpdateMessage.fromMessageDescription(updateDescription);
-    }
+    LiveData<SpannableString> spannableStringMessage = Transformations.map(liveUpdateMessage, SpannableString::new);
 
     present(messageRecord);
+
+    observeDisplayBody(spannableStringMessage);
+  }
+
+  private void observeDisplayBody(@Nullable LiveData<SpannableString> displayBody) {
+    if (this.displayBody != displayBody) {
+      if (this.displayBody != null) {
+        this.displayBody.removeObserver(this);
+      }
+
+      this.displayBody = displayBody;
+
+      if (this.displayBody != null) {
+        this.displayBody.observeForever(this);
+      }
+    }
+  }
+
+  private void setBodyText(@Nullable CharSequence text) {
+    if (text == null) {
+      bodyClearDebouncer.publish(() -> body.setText(null));
+    } else {
+      bodyClearDebouncer.clear();
+      body.setText(text);
+      body.setVisibility(VISIBLE);
+    }
   }
 
   private void present(MessageRecord messageRecord) {
-    if      (messageRecord.isGroupAction())           setGroupRecord(messageRecord);
+    if      (messageRecord.isGroupAction())           setGroupRecord();
     else if (messageRecord.isCallLog())               setCallRecord(messageRecord);
-    else if (messageRecord.isJoined())                setJoinedRecord(messageRecord);
+    else if (messageRecord.isJoined())                setJoinedRecord();
     else if (messageRecord.isExpirationTimerUpdate()) setTimerRecord(messageRecord);
-    else if (messageRecord.isEndSession())            setEndSessionRecord(messageRecord);
+    else if (messageRecord.isEndSession())            setEndSessionRecord();
-    else if (messageRecord.isIdentityUpdate())        setIdentityRecord(messageRecord);
+    else if (messageRecord.isIdentityUpdate())        setIdentityRecord();
     else if (messageRecord.isIdentityVerified() ||
              messageRecord.isIdentityDefault())       setIdentityVerifyUpdate(messageRecord);
-    else if (messageRecord.isProfileChange())         setProfileNameChangeRecord(messageRecord);
+    else if (messageRecord.isProfileChange())         setProfileNameChangeRecord();
     else                                              throw new AssertionError("Neither group nor log nor joined.");
 
     if (batchSelected.contains(messageRecord)) setSelected(true);
@@ -146,11 +183,9 @@ public class ConversationUpdateItem extends LinearLayout
     else if (messageRecord.isOutgoingCall()) icon.setImageResource(R.drawable.ic_call_made_grey600_24dp);
     else                                     icon.setImageResource(R.drawable.ic_call_missed_grey600_24dp);
 
-    body.setText(messageRecord.getDisplayBody(getContext()));
     date.setText(DateUtils.getExtendedRelativeTimeSpanString(getContext(), locale, messageRecord.getDateReceived()));
 
     title.setVisibility(GONE);
-    body.setVisibility(VISIBLE);
     date.setVisibility(View.VISIBLE);
   }
 
@@ -163,10 +198,8 @@ public class ConversationUpdateItem extends LinearLayout
 
     icon.setColorFilter(getIconTintFilter());
     title.setText(ExpirationUtil.getExpirationDisplayValue(getContext(), (int)(messageRecord.getExpiresIn() / 1000)));
-    body.setText(messageRecord.getDisplayBody(getContext()));
 
     title.setVisibility(VISIBLE);
-    body.setVisibility(VISIBLE);
     date.setVisibility(GONE);
   }
 
@@ -174,13 +207,11 @@ public class ConversationUpdateItem extends LinearLayout
     return new PorterDuffColorFilter(ThemeUtil.getThemedColor(getContext(), R.attr.icon_tint), PorterDuff.Mode.SRC_IN);
   }
 
-  private void setIdentityRecord(final MessageRecord messageRecord) {
+  private void setIdentityRecord() {
     icon.setImageDrawable(ThemeUtil.getThemedDrawable(getContext(), R.attr.safety_number_icon));
     icon.setColorFilter(getIconTintFilter());
-    body.setText(messageRecord.getDisplayBody(getContext()));
 
     title.setVisibility(GONE);
-    body.setVisibility(VISIBLE);
     date.setVisibility(GONE);
   }
 
@@ -189,52 +220,38 @@ public class ConversationUpdateItem extends LinearLayout
     else                                    icon.setImageResource(R.drawable.ic_info_outline_white_24dp);
 
     icon.setColorFilter(getIconTintFilter());
-    body.setText(messageRecord.getDisplayBody(getContext()));
 
     title.setVisibility(GONE);
-    body.setVisibility(VISIBLE);
     date.setVisibility(GONE);
   }
 
-  private void setProfileNameChangeRecord(MessageRecord messageRecord) {
+  private void setProfileNameChangeRecord() {
     icon.setImageDrawable(ContextCompat.getDrawable(getContext(), R.drawable.ic_profile_outline_20));
     icon.setColorFilter(getIconTintFilter());
-    body.setText(messageRecord.getDisplayBody(getContext()));
 
     title.setVisibility(GONE);
-    body.setVisibility(VISIBLE);
     date.setVisibility(GONE);
   }
 
-  private void setGroupRecord(MessageRecord messageRecord) {
+  private void setGroupRecord() {
     icon.setImageDrawable(ThemeUtil.getThemedDrawable(getContext(), R.attr.menu_group_icon));
     icon.clearColorFilter();
 
-    body.setText(messageRecord.getDisplayBody(getContext()));
-
     title.setVisibility(GONE);
-    body.setVisibility(VISIBLE);
     date.setVisibility(GONE);
   }
 
-  private void setJoinedRecord(MessageRecord messageRecord) {
+  private void setJoinedRecord() {
     icon.setImageResource(R.drawable.ic_favorite_grey600_24dp);
     icon.clearColorFilter();
-    body.setText(messageRecord.getDisplayBody(getContext()));
 
     title.setVisibility(GONE);
-    body.setVisibility(VISIBLE);
     date.setVisibility(GONE);
   }
 
-  private void setEndSessionRecord(MessageRecord messageRecord) {
+  private void setEndSessionRecord() {
     icon.setImageResource(R.drawable.ic_refresh_white_24dp);
     icon.setColorFilter(getIconTintFilter());
-    body.setText(messageRecord.getDisplayBody(getContext()));
-
-    title.setVisibility(GONE);
-    body.setVisibility(VISIBLE);
-    date.setVisibility(GONE);
   }
 
   @Override
@@ -252,9 +269,13 @@ public class ConversationUpdateItem extends LinearLayout
     if (sender != null) {
       sender.removeForeverObserver(this);
     }
-    if (this.messageRecord != null && messageRecord.isGroupAction()) {
+
-      GroupUtil.getDescription(getContext(), messageRecord.getBody(), messageRecord.isGroupV2()).removeObserver(this);
+    observeDisplayBody(null);
   }
+
+  @Override
+  public void onChanged(SpannableString update) {
+    setBodyText(update);
   }
 
   private class InternalClickListener implements View.OnClickListener {

app/src/main/java/org/thoughtcrime/securesms/conversationlist/ConversationListItem.java

@@ -21,7 +21,6 @@ import android.content.res.ColorStateList;
 import android.graphics.Typeface;
 import android.graphics.drawable.RippleDrawable;
 import android.os.Build.VERSION;
-import android.os.Build.VERSION_CODES;
 import android.text.Spannable;
 import android.text.SpannableString;
 import android.text.style.StyleSpan;
@@ -32,6 +31,9 @@ import android.widget.TextView;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.Observer;
+import androidx.lifecycle.Transformations;
 
 import org.thoughtcrime.securesms.BindableConversationListItem;
 import org.thoughtcrime.securesms.R;
@@ -42,41 +44,49 @@ import org.thoughtcrime.securesms.components.DeliveryStatusView;
 import org.thoughtcrime.securesms.components.FromTextView;
 import org.thoughtcrime.securesms.components.ThumbnailView;
 import org.thoughtcrime.securesms.components.TypingIndicatorView;
+import org.thoughtcrime.securesms.conversationlist.model.MessageResult;
 import org.thoughtcrime.securesms.database.MmsSmsColumns;
 import org.thoughtcrime.securesms.database.SmsDatabase;
 import org.thoughtcrime.securesms.database.ThreadDatabase;
+import org.thoughtcrime.securesms.database.model.LiveUpdateMessage;
+import org.thoughtcrime.securesms.database.model.MessageRecord;
 import org.thoughtcrime.securesms.database.model.ThreadRecord;
+import org.thoughtcrime.securesms.database.model.UpdateDescription;
+import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.mms.GlideRequests;
 import org.thoughtcrime.securesms.recipients.LiveRecipient;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.recipients.RecipientForeverObserver;
-import org.thoughtcrime.securesms.conversationlist.model.MessageResult;
 import org.thoughtcrime.securesms.util.DateUtils;
+import org.thoughtcrime.securesms.util.Debouncer;
 import org.thoughtcrime.securesms.util.ExpirationUtil;
 import org.thoughtcrime.securesms.util.MediaUtil;
 import org.thoughtcrime.securesms.util.SearchUtil;
 import org.thoughtcrime.securesms.util.ThemeUtil;
 import org.thoughtcrime.securesms.util.ViewUtil;
+import org.thoughtcrime.securesms.util.livedata.LiveDataUtil;
 
 import java.util.Collections;
 import java.util.Locale;
 import java.util.Set;
 
-public class ConversationListItem extends RelativeLayout
+import static org.thoughtcrime.securesms.database.model.LiveUpdateMessage.recipientToStringAsync;
+
+public final class ConversationListItem extends RelativeLayout
                                         implements RecipientForeverObserver,
-    BindableConversationListItem, Unbindable
+                                                   BindableConversationListItem,
+                                                   Unbindable,
+                                                   Observer<SpannableString>
 {
   @SuppressWarnings("unused")
-  private final static String TAG = ConversationListItem.class.getSimpleName();
+  private final static String TAG = Log.tag(ConversationListItem.class);
 
   private final static Typeface  BOLD_TYPEFACE  = Typeface.create("sans-serif-medium", Typeface.NORMAL);
   private final static Typeface  LIGHT_TYPEFACE = Typeface.create("sans-serif", Typeface.NORMAL);
 
-  private static final int MAX_SNIPPET_LENGTH = 500;
-
   private Set<Long>           selectedThreads;
+  private Set<Long>           typingThreads;
   private LiveRecipient       recipient;
-  private LiveRecipient       groupAddedBy;
   private long                threadId;
   private GlideRequests       glideRequests;
   private View                subjectContainer;
@@ -96,13 +106,9 @@ public class ConversationListItem extends RelativeLayout
   private AvatarImageView contactPhotoImage;
   private ThumbnailView   thumbnailView;
 
-  private int distributionType;
+  private final Debouncer subjectViewClearDebouncer = new Debouncer(150);
 
-  private final RecipientForeverObserver groupAddedByObserver = adder -> {
+  private LiveData<SpannableString> displayBody;
-    if (isAttachedToWindow() && subjectView != null && thread != null) {
-      subjectView.setText(getThreadDisplayBody(getContext(), thread));
-    }
-  };
 
   public ConversationListItem(Context context) {
     this(context, null);
@@ -152,14 +158,14 @@ public class ConversationListItem extends RelativeLayout
                    @Nullable String highlightSubstring)
   {
     if (this.recipient != null) this.recipient.removeForeverObserver(this);
-    if (this.groupAddedBy != null) this.groupAddedBy.removeForeverObserver(groupAddedByObserver);
+    observeDisplayBody(null);
+    setSubjectViewText(null);
 
     this.selectedThreads = selectedThreads;
     this.recipient       = thread.getRecipient().live();
     this.threadId        = thread.getThreadId();
     this.glideRequests   = glideRequests;
     this.unreadCount     = thread.getUnreadCount();
-    this.distributionType = thread.getDistributionType();
     this.lastSeen        = thread.getLastSeen();
     this.thread          = thread;
 
@@ -172,14 +178,10 @@ public class ConversationListItem extends RelativeLayout
       this.fromView.setText(recipient.get(), thread.isRead());
     }
 
+    this.typingThreads = typingThreads;
     updateTypingIndicator(typingThreads);
 
-    this.subjectView.setText(getTrimmedSnippet(getThreadDisplayBody(getContext(), thread)));
+    observeDisplayBody(getThreadDisplayBody(getContext(), thread));
-
-    if (thread.getGroupAddedBy() != null) {
-      groupAddedBy = Recipient.live(thread.getGroupAddedBy());
-      groupAddedBy.observeForever(groupAddedByObserver);
-    }
 
     this.subjectView.setTypeface(thread.isRead() ? LIGHT_TYPEFACE : BOLD_TYPEFACE);
     this.subjectView.setTextColor(thread.isRead() ? ThemeUtil.getThemedColor(getContext(), R.attr.conversation_list_item_subject_color)
@@ -213,7 +215,8 @@ public class ConversationListItem extends RelativeLayout
                    @Nullable String        highlightSubstring)
   {
     if (this.recipient != null) this.recipient.removeForeverObserver(this);
-    if (this.groupAddedBy != null) this.groupAddedBy.removeForeverObserver(groupAddedByObserver);
+    observeDisplayBody(null);
+    setSubjectViewText(null);
 
     this.selectedThreads = Collections.emptySet();
     this.recipient       = contact.live();
@@ -242,7 +245,8 @@ public class ConversationListItem extends RelativeLayout
                    @Nullable String        highlightSubstring)
   {
     if (this.recipient != null) this.recipient.removeForeverObserver(this);
-    if (this.groupAddedBy != null) this.groupAddedBy.removeForeverObserver(groupAddedByObserver);
+    observeDisplayBody(null);
+    setSubjectViewText(null);
 
     this.selectedThreads = Collections.emptySet();
     this.recipient       = messageResult.conversationRecipient.live();
@@ -274,10 +278,7 @@ public class ConversationListItem extends RelativeLayout
       contactPhotoImage.setAvatar(glideRequests, null, !batchMode);
     }
 
-    if (this.groupAddedBy != null) {
+    observeDisplayBody(null);
-      this.groupAddedBy.removeForeverObserver(groupAddedByObserver);
-      this.groupAddedBy = null;
-    }
   }
 
   @Override
@@ -317,17 +318,30 @@ public class ConversationListItem extends RelativeLayout
     return unreadCount;
   }
 
-  public int getDistributionType() {
-    return distributionType;
-  }
-
   public long getLastSeen() {
     return lastSeen;
   }
 
-  private static @NonNull CharSequence getTrimmedSnippet(@NonNull CharSequence snippet) {
+  private void observeDisplayBody(@Nullable LiveData<SpannableString> displayBody) {
-    return snippet.length() <= MAX_SNIPPET_LENGTH ? snippet
+    if (this.displayBody != null) {
-                                                  : snippet.subSequence(0, MAX_SNIPPET_LENGTH);
+      this.displayBody.removeObserver(this);
+    }
+
+    this.displayBody = displayBody;
+
+    if (this.displayBody != null) {
+      this.displayBody.observeForever(this);
+    }
+  }
+
+  private void setSubjectViewText(@Nullable CharSequence text) {
+    if (text == null) {
+      subjectViewClearDebouncer.publish(() -> subjectView.setText(null));
+    } else {
+      subjectViewClearDebouncer.clear();
+      subjectView.setText(text);
+      subjectView.setVisibility(VISIBLE);
+    }
   }
 
   private void setThumbnailSnippet(ThreadRecord thread) {
@@ -371,7 +385,7 @@ public class ConversationListItem extends RelativeLayout
   }
 
   private void setRippleColor(Recipient recipient) {
-    if (VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP) {
+    if (VERSION.SDK_INT >= 21) {
       ((RippleDrawable)(getBackground()).mutate())
           .setColor(ColorStateList.valueOf(recipient.getColor().toConversationColor(getContext())));
     }
@@ -394,16 +408,20 @@ public class ConversationListItem extends RelativeLayout
     setRippleColor(recipient);
   }
 
-
+  private static @NonNull LiveData<SpannableString> getThreadDisplayBody(@NonNull Context context, @NonNull ThreadRecord thread) {
-  private static SpannableString getThreadDisplayBody(@NonNull Context context, @NonNull ThreadRecord thread) {
     if (thread.getGroupAddedBy() != null) {
-      return emphasisAdded(context.getString(thread.isGv2Invite() ? R.string.ThreadRecord_s_invited_you_to_the_group
+      return emphasisAdded(recipientToStringAsync(thread.getGroupAddedBy(),
+                                                  r -> context.getString(thread.isGv2Invite() ? R.string.ThreadRecord_s_invited_you_to_the_group
                                                                                               : R.string.ThreadRecord_s_added_you_to_the_group,
-                                             Recipient.live(thread.getGroupAddedBy()).get().getDisplayName(context)));
+                                                                         r.getDisplayName(context))));
     } else if (!thread.isMessageRequestAccepted()) {
       return emphasisAdded(context.getString(R.string.ThreadRecord_message_request));
     } else if (SmsDatabase.Types.isGroupUpdate(thread.getType())) {
+      if (thread.getRecipient().isPushV2Group()) {
+        return emphasisAdded(MessageRecord.getGv2ChangeDescription(context, thread.getBody()));
+      } else {
         return emphasisAdded(context.getString(R.string.ThreadRecord_group_updated));
+      }
     } else if (SmsDatabase.Types.isGroupQuit(thread.getType())) {
       return emphasisAdded(context.getString(R.string.ThreadRecord_left_the_group));
     } else if (SmsDatabase.Types.isKeyExchangeType(thread.getType())) {
@@ -418,15 +436,15 @@ public class ConversationListItem extends RelativeLayout
       return emphasisAdded(context.getString(R.string.MessageRecord_message_encrypted_with_a_legacy_protocol_version_that_is_no_longer_supported));
     } else if (MmsSmsColumns.Types.isDraftMessageType(thread.getType())) {
       String draftText = context.getString(R.string.ThreadRecord_draft);
-      return emphasisAdded(draftText + " " + thread.getBody(), 0, draftText.length());
+      return emphasisAdded(draftText + " " + thread.getBody());
     } else if (SmsDatabase.Types.isOutgoingCall(thread.getType())) {
-      return emphasisAdded(context.getString(org.thoughtcrime.securesms.R.string.ThreadRecord_called));
+      return emphasisAdded(context.getString(R.string.ThreadRecord_called));
     } else if (SmsDatabase.Types.isIncomingCall(thread.getType())) {
-      return emphasisAdded(context.getString(org.thoughtcrime.securesms.R.string.ThreadRecord_called_you));
+      return emphasisAdded(context.getString(R.string.ThreadRecord_called_you));
     } else if (SmsDatabase.Types.isMissedCall(thread.getType())) {
-      return emphasisAdded(context.getString(org.thoughtcrime.securesms.R.string.ThreadRecord_missed_call));
+      return emphasisAdded(context.getString(R.string.ThreadRecord_missed_call));
     } else if (SmsDatabase.Types.isJoinedType(thread.getType())) {
-      return emphasisAdded(context.getString(R.string.ThreadRecord_s_is_on_signal, thread.getRecipient().getDisplayName(context)));
+      return emphasisAdded(recipientToStringAsync(thread.getRecipient().getId(), r -> context.getString(R.string.ThreadRecord_s_is_on_signal, r.getDisplayName(context))));
     } else if (SmsDatabase.Types.isExpirationTimerUpdate(thread.getType())) {
       int seconds = (int)(thread.getExpiresIn() / 1000);
       if (seconds <= 0) {
@@ -438,7 +456,7 @@ public class ConversationListItem extends RelativeLayout
       if (thread.getRecipient().isGroup()) {
         return emphasisAdded(context.getString(R.string.ThreadRecord_safety_number_changed));
       } else {
-        return emphasisAdded(context.getString(R.string.ThreadRecord_your_safety_number_with_s_has_changed, thread.getRecipient().getDisplayName(context)));
+        return emphasisAdded(recipientToStringAsync(thread.getRecipient().getId(), r -> context.getString(R.string.ThreadRecord_your_safety_number_with_s_has_changed, r.getDisplayName(context))));
       }
     } else if (SmsDatabase.Types.isIdentityVerified(thread.getType())) {
       return emphasisAdded(context.getString(R.string.ThreadRecord_you_marked_verified));
@@ -449,11 +467,11 @@ public class ConversationListItem extends RelativeLayout
     } else {
       ThreadDatabase.Extra extra = thread.getExtra();
       if (extra != null && extra.isViewOnce()) {
-        return new SpannableString(emphasisAdded(getViewOnceDescription(context, thread.getContentType())));
+        return emphasisAdded(getViewOnceDescription(context, thread.getContentType()));
       } else if (extra != null && extra.isRemoteDelete()) {
-        return new SpannableString(emphasisAdded(context.getString(thread.isOutgoing() ? R.string.ThreadRecord_you_deleted_this_message : R.string.ThreadRecord_this_message_was_deleted)));
+        return emphasisAdded(context.getString(thread.isOutgoing() ? R.string.ThreadRecord_you_deleted_this_message : R.string.ThreadRecord_this_message_was_deleted));
       } else {
-        return new SpannableString(removeNewlines(thread.getBody()));
+        return LiveDataUtil.just(new SpannableString(removeNewlines(thread.getBody())));
       }
     }
   }
@@ -470,17 +488,23 @@ public class ConversationListItem extends RelativeLayout
     }
   }
 
-  private static @NonNull SpannableString emphasisAdded(String sequence) {
+  private static @NonNull LiveData<SpannableString> emphasisAdded(@NonNull String string) {
-    return emphasisAdded(sequence, 0, sequence.length());
+    return emphasisAdded(UpdateDescription.staticDescription(string));
   }
 
-  private static @NonNull SpannableString emphasisAdded(String sequence, int start, int end) {
+  private static @NonNull LiveData<SpannableString> emphasisAdded(@NonNull UpdateDescription description) {
+    return emphasisAdded(LiveUpdateMessage.fromMessageDescription(description));
+  }
+
+  private static @NonNull LiveData<SpannableString> emphasisAdded(@NonNull LiveData<String> description) {
+    return Transformations.map(description, sequence -> {
       SpannableString spannable = new SpannableString(sequence);
-    spannable.setSpan(new StyleSpan(android.graphics.Typeface.ITALIC),
+      spannable.setSpan(new StyleSpan(Typeface.ITALIC),
-                      start,
+                                      0,
-                      end,
+                                      sequence.length(),
                                       Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
       return spannable;
+    });
   }
 
   private static String getViewOnceDescription(@NonNull Context context, @Nullable String contentType) {
@@ -493,6 +517,15 @@ public class ConversationListItem extends RelativeLayout
     }
   }
 
+  @Override
+  public void onChanged(SpannableString spannableString) {
+    setSubjectViewText(spannableString);
+
+    if (typingThreads != null) {
+      updateTypingIndicator(typingThreads);
+    }
+  }
+
   private static class ThumbnailPositioner implements Runnable {
 
     private final View thumbnailView;

app/src/main/java/org/thoughtcrime/securesms/database/model/GroupsV2UpdateMessageProducer.java

@@ -3,6 +3,7 @@ package org.thoughtcrime.securesms.database.model;
 import android.content.Context;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.WorkerThread;
 
 import com.google.protobuf.ByteString;
 
@@ -21,6 +22,8 @@ import org.whispersystems.libsignal.util.guava.Optional;
 import org.whispersystems.signalservice.api.groupsv2.DecryptedGroupUtil;
 import org.whispersystems.signalservice.api.util.UuidUtil;
 
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.UUID;
@@ -37,8 +40,7 @@ final class GroupsV2UpdateMessageProducer {
    */
   GroupsV2UpdateMessageProducer(@NonNull Context context,
                                 @NonNull DescribeMemberStrategy descriptionStrategy,
-                                @NonNull UUID selfUuid)
+                                @NonNull UUID selfUuid) {
-  {
     this.context             = context;
     this.descriptionStrategy = descriptionStrategy;
     this.selfUuid            = selfUuid;
@@ -50,10 +52,10 @@ final class GroupsV2UpdateMessageProducer {
    * <p>
    * Invitation and groups you create are the most common cases where no change is available.
    */
-  String describeNewGroup(@NonNull DecryptedGroup group) {
+  UpdateDescription describeNewGroup(@NonNull DecryptedGroup group) {
     Optional<DecryptedPendingMember> selfPending = DecryptedGroupUtil.findPendingByUuid(group.getPendingMembersList(), selfUuid);
     if (selfPending.isPresent()) {
-      return context.getString(R.string.MessageRecord_s_invited_you_to_the_group, describe(selfPending.get().getAddedByUuid()));
+      return updateDescription(selfPending.get().getAddedByUuid(), inviteBy -> context.getString(R.string.MessageRecord_s_invited_you_to_the_group, inviteBy));
     }
 
     if (group.getRevision() == 0) {
@@ -61,22 +63,22 @@ final class GroupsV2UpdateMessageProducer {
       if (foundingMember.isPresent()) {
         ByteString foundingMemberUuid = foundingMember.get().getUuid();
         if (selfUuidBytes.equals(foundingMemberUuid)) {
-          return context.getString(R.string.MessageRecord_you_created_the_group);
+          return updateDescription(context.getString(R.string.MessageRecord_you_created_the_group));
         } else {
-          return context.getString(R.string.MessageRecord_s_added_you, describe(foundingMemberUuid));
+          return updateDescription(foundingMemberUuid, creator -> context.getString(R.string.MessageRecord_s_added_you, creator));
         }
       }
     }
 
     if (DecryptedGroupUtil.findMemberByUuid(group.getMembersList(), selfUuid).isPresent()) {
-      return context.getString(R.string.MessageRecord_you_joined_the_group);
+      return updateDescription(context.getString(R.string.MessageRecord_you_joined_the_group));
     } else {
-      return context.getString(R.string.MessageRecord_group_updated);
+      return updateDescription(context.getString(R.string.MessageRecord_group_updated));
     }
   }
 
-  List<String> describeChange(@NonNull DecryptedGroupChange change) {
+  List<UpdateDescription> describeChanges(@NonNull DecryptedGroupChange change) {
-    List<String> updates = new LinkedList<>();
+    List<UpdateDescription> updates = new LinkedList<>();
 
     if (change.getEditor().isEmpty() || UuidUtil.UNKNOWN_UUID.equals(UuidUtil.fromByteString(change.getEditor()))) {
       describeUnknownEditorMemberAdditions(change, updates);
@@ -119,21 +121,21 @@ final class GroupsV2UpdateMessageProducer {
   /**
    * Handles case of future protocol versions where we don't know what has changed.
    */
-  private void describeUnknownChange(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownChange(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     if (editorIsYou) {
-      updates.add(context.getString(R.string.MessageRecord_you_updated_group));
+      updates.add(updateDescription(context.getString(R.string.MessageRecord_you_updated_group)));
     } else {
-      updates.add(context.getString(R.string.MessageRecord_s_updated_group, describe(change.getEditor())));
+      updates.add(updateDescription(change.getEditor(), (editor) -> context.getString(R.string.MessageRecord_s_updated_group, editor)));
     }
   }
 
-  private void describeUnknownEditorUnknownChange(@NonNull List<String> updates) {
+  private void describeUnknownEditorUnknownChange(@NonNull List<UpdateDescription> updates) {
-    updates.add(context.getString(R.string.MessageRecord_the_group_was_updated));
+    updates.add(updateDescription(context.getString(R.string.MessageRecord_the_group_was_updated)));
   }
 
-  private void describeMemberAdditions(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeMemberAdditions(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     for (DecryptedMember member : change.getNewMembersList()) {
@@ -141,37 +143,37 @@ final class GroupsV2UpdateMessageProducer {
 
       if (editorIsYou) {
         if (newMemberIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_you_joined_the_group));
+          updates.add(updateDescription(context.getString(R.string.MessageRecord_you_joined_the_group)));
         } else {
-          updates.add(context.getString(R.string.MessageRecord_you_added_s, describe(member.getUuid())));
+          updates.add(updateDescription(member.getUuid(), added -> context.getString(R.string.MessageRecord_you_added_s, added)));
         }
       } else {
         if (newMemberIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_s_added_you, describe(change.getEditor())));
+          updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_added_you, editor)));
         } else {
           if (member.getUuid().equals(change.getEditor())) {
-            updates.add(context.getString(R.string.MessageRecord_s_joined_the_group, describe(member.getUuid())));
+            updates.add(updateDescription(member.getUuid(), newMember -> context.getString(R.string.MessageRecord_s_joined_the_group, newMember)));
           } else {
-            updates.add(context.getString(R.string.MessageRecord_s_added_s, describe(change.getEditor()), describe(member.getUuid())));
+            updates.add(updateDescription(change.getEditor(), member.getUuid(), (editor, newMember) -> context.getString(R.string.MessageRecord_s_added_s, editor, newMember)));
           }
         }
       }
     }
   }
 
-  private void describeUnknownEditorMemberAdditions(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorMemberAdditions(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     for (DecryptedMember member : change.getNewMembersList()) {
       boolean newMemberIsYou = member.getUuid().equals(selfUuidBytes);
 
       if (newMemberIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_you_joined_the_group));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_you_joined_the_group)));
       } else {
-        updates.add(context.getString(R.string.MessageRecord_s_joined_the_group, describe(member.getUuid())));
+        updates.add(updateDescription(member.getUuid(), newMember -> context.getString(R.string.MessageRecord_s_joined_the_group, newMember)));
       }
     }
   }
 
-  private void describeMemberRemovals(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeMemberRemovals(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     for (ByteString member : change.getDeleteMembersList()) {
@@ -179,87 +181,87 @@ final class GroupsV2UpdateMessageProducer {
 
       if (editorIsYou) {
         if (removedMemberIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_you_left_the_group));
+          updates.add(updateDescription(context.getString(R.string.MessageRecord_you_left_the_group)));
         } else {
-          updates.add(context.getString(R.string.MessageRecord_you_removed_s, describe(member)));
+          updates.add(updateDescription(member, removedMember -> context.getString(R.string.MessageRecord_you_removed_s, removedMember)));
         }
       } else {
         if (removedMemberIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_s_removed_you_from_the_group, describe(change.getEditor())));
+          updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_removed_you_from_the_group, editor)));
         } else {
           if (member.equals(change.getEditor())) {
-            updates.add(context.getString(R.string.MessageRecord_s_left_the_group, describe(member)));
+            updates.add(updateDescription(member, leavingMember -> context.getString(R.string.MessageRecord_s_left_the_group, leavingMember)));
           } else {
-            updates.add(context.getString(R.string.MessageRecord_s_removed_s, describe(change.getEditor()), describe(member)));
+            updates.add(updateDescription(change.getEditor(), member, (editor, removedMember) -> context.getString(R.string.MessageRecord_s_removed_s, editor, removedMember)));
           }
         }
       }
     }
   }
 
-  private void describeUnknownEditorMemberRemovals(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorMemberRemovals(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     for (ByteString member : change.getDeleteMembersList()) {
       boolean removedMemberIsYou = member.equals(selfUuidBytes);
 
       if (removedMemberIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_you_are_no_longer_in_the_group));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_you_are_no_longer_in_the_group)));
       } else {
-        updates.add(context.getString(R.string.MessageRecord_s_is_no_longer_in_the_group, describe(member)));
+        updates.add(updateDescription(member, oldMember -> context.getString(R.string.MessageRecord_s_is_no_longer_in_the_group, oldMember)));
       }
     }
   }
 
-  private void describeModifyMemberRoles(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeModifyMemberRoles(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     for (DecryptedModifyMemberRole roleChange : change.getModifyMemberRolesList()) {
       boolean changedMemberIsYou = roleChange.getUuid().equals(selfUuidBytes);
       if (roleChange.getRole() == Member.Role.ADMINISTRATOR) {
         if (editorIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_you_made_s_an_admin, describe(roleChange.getUuid())));
+          updates.add(updateDescription(roleChange.getUuid(), newAdmin -> context.getString(R.string.MessageRecord_you_made_s_an_admin, newAdmin)));
         } else {
           if (changedMemberIsYou) {
-            updates.add(context.getString(R.string.MessageRecord_s_made_you_an_admin, describe(change.getEditor())));
+            updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_made_you_an_admin, editor)));
           } else {
-            updates.add(context.getString(R.string.MessageRecord_s_made_s_an_admin, describe(change.getEditor()), describe(roleChange.getUuid())));
+            updates.add(updateDescription(change.getEditor(), roleChange.getUuid(), (editor, newAdmin) -> context.getString(R.string.MessageRecord_s_made_s_an_admin, editor, newAdmin)));
 
           }
         }
       } else {
         if (editorIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_you_revoked_admin_privileges_from_s, describe(roleChange.getUuid())));
+          updates.add(updateDescription(roleChange.getUuid(), oldAdmin -> context.getString(R.string.MessageRecord_you_revoked_admin_privileges_from_s, oldAdmin)));
         } else {
           if (changedMemberIsYou) {
-            updates.add(context.getString(R.string.MessageRecord_s_revoked_your_admin_privileges, describe(change.getEditor())));
+            updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_revoked_your_admin_privileges, editor)));
           } else {
-            updates.add(context.getString(R.string.MessageRecord_s_revoked_admin_privileges_from_s, describe(change.getEditor()), describe(roleChange.getUuid())));
+            updates.add(updateDescription(change.getEditor(), roleChange.getUuid(), (editor, oldAdmin) -> context.getString(R.string.MessageRecord_s_revoked_admin_privileges_from_s, editor, oldAdmin)));
           }
         }
       }
     }
   }
 
-  private void describeUnknownEditorModifyMemberRoles(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorModifyMemberRoles(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     for (DecryptedModifyMemberRole roleChange : change.getModifyMemberRolesList()) {
       boolean changedMemberIsYou = roleChange.getUuid().equals(selfUuidBytes);
 
       if (roleChange.getRole() == Member.Role.ADMINISTRATOR) {
         if (changedMemberIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_you_are_now_an_admin));
+          updates.add(updateDescription(context.getString(R.string.MessageRecord_you_are_now_an_admin)));
         } else {
-          updates.add(context.getString(R.string.MessageRecord_s_is_now_an_admin, describe(roleChange.getUuid())));
+          updates.add(updateDescription(roleChange.getUuid(), newAdmin -> context.getString(R.string.MessageRecord_s_is_now_an_admin, newAdmin)));
         }
       } else {
         if (changedMemberIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_you_are_no_longer_an_admin));
+          updates.add(updateDescription(context.getString(R.string.MessageRecord_you_are_no_longer_an_admin)));
         } else {
-          updates.add(context.getString(R.string.MessageRecord_s_is_no_longer_an_admin, describe(roleChange.getUuid())));
+          updates.add(updateDescription(roleChange.getUuid(), oldAdmin -> context.getString(R.string.MessageRecord_s_is_no_longer_an_admin, oldAdmin)));
         }
       }
     }
   }
 
-  private void describeInvitations(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeInvitations(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
     int notYouInviteCount = 0;
 
@@ -267,10 +269,10 @@ final class GroupsV2UpdateMessageProducer {
       boolean newMemberIsYou = invitee.getUuid().equals(selfUuidBytes);
 
       if (newMemberIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_s_invited_you_to_the_group, describe(change.getEditor())));
+        updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_invited_you_to_the_group, editor)));
       } else {
         if (editorIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_you_invited_s_to_the_group, describe(invitee.getUuid())));
+          updates.add(updateDescription(invitee.getUuid(), newInvitee -> context.getString(R.string.MessageRecord_you_invited_s_to_the_group, newInvitee)));
         } else {
           notYouInviteCount++;
         }
@@ -278,29 +280,30 @@ final class GroupsV2UpdateMessageProducer {
     }
 
     if (notYouInviteCount > 0) {
-      updates.add(context.getResources().getQuantityString(R.plurals.MessageRecord_s_invited_members, notYouInviteCount, describe(change.getEditor()), notYouInviteCount));
+      final int notYouInviteCountFinalCopy = notYouInviteCount;
+      updates.add(updateDescription(change.getEditor(), editor -> context.getResources().getQuantityString(R.plurals.MessageRecord_s_invited_members, notYouInviteCountFinalCopy, editor, notYouInviteCountFinalCopy)));
     }
   }
 
-  private void describeUnknownEditorInvitations(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorInvitations(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     int notYouInviteCount = 0;
 
     for (DecryptedPendingMember invitee : change.getNewPendingMembersList()) {
       boolean newMemberIsYou = invitee.getUuid().equals(selfUuidBytes);
 
       if (newMemberIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_you_were_invited_to_the_group));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_you_were_invited_to_the_group)));
       } else {
         notYouInviteCount++;
       }
     }
 
     if (notYouInviteCount > 0) {
-      updates.add(context.getResources().getQuantityString(R.plurals.MessageRecord_d_people_were_invited_to_the_group, notYouInviteCount, notYouInviteCount));
+      updates.add(updateDescription(context.getResources().getQuantityString(R.plurals.MessageRecord_d_people_were_invited_to_the_group, notYouInviteCount, notYouInviteCount)));
     }
   }
 
-  private void describeRevokedInvitations(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeRevokedInvitations(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
     int notDeclineCount = 0;
 
@@ -308,9 +311,9 @@ final class GroupsV2UpdateMessageProducer {
       boolean decline = invitee.getUuid().equals(change.getEditor());
       if (decline) {
         if (editorIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_you_declined_the_invitation_to_the_group));
+          updates.add(updateDescription(context.getString(R.string.MessageRecord_you_declined_the_invitation_to_the_group)));
         } else {
-          updates.add(context.getString(R.string.MessageRecord_someone_declined_an_invitation_to_the_group));
+          updates.add(updateDescription(context.getString(R.string.MessageRecord_someone_declined_an_invitation_to_the_group)));
         }
       } else {
         notDeclineCount++;
@@ -319,32 +322,33 @@ final class GroupsV2UpdateMessageProducer {
 
     if (notDeclineCount > 0) {
       if (editorIsYou) {
-        updates.add(context.getResources().getQuantityString(R.plurals.MessageRecord_you_revoked_invites, notDeclineCount, notDeclineCount));
+        updates.add(updateDescription(context.getResources().getQuantityString(R.plurals.MessageRecord_you_revoked_invites, notDeclineCount, notDeclineCount)));
       } else {
-        updates.add(context.getResources().getQuantityString(R.plurals.MessageRecord_s_revoked_invites, notDeclineCount, describe(change.getEditor()), notDeclineCount));
+        final int notDeclineCountFinalCopy = notDeclineCount;
+        updates.add(updateDescription(change.getEditor(), editor -> context.getResources().getQuantityString(R.plurals.MessageRecord_s_revoked_invites, notDeclineCountFinalCopy, editor, notDeclineCountFinalCopy)));
       }
     }
   }
 
-  private void describeUnknownEditorRevokedInvitations(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorRevokedInvitations(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     int notDeclineCount = 0;
 
     for (DecryptedPendingMemberRemoval invitee : change.getDeletePendingMembersList()) {
       boolean inviteeWasYou = invitee.getUuid().equals(selfUuidBytes);
 
       if (inviteeWasYou) {
-        updates.add(context.getString(R.string.MessageRecord_your_invitation_to_the_group_was_revoked));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_your_invitation_to_the_group_was_revoked)));
       } else {
         notDeclineCount++;
       }
     }
 
     if (notDeclineCount > 0) {
-      updates.add(context.getResources().getQuantityString(R.plurals.MessageRecord_d_invitations_were_revoked, notDeclineCount, notDeclineCount));
+      updates.add(updateDescription(context.getResources().getQuantityString(R.plurals.MessageRecord_d_invitations_were_revoked, notDeclineCount, notDeclineCount)));
     }
   }
 
-  private void describePromotePending(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describePromotePending(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     for (DecryptedMember newMember : change.getPromotePendingMembersList()) {
@@ -353,142 +357,166 @@ final class GroupsV2UpdateMessageProducer {
 
       if (editorIsYou) {
         if (newMemberIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_you_accepted_invite));
+          updates.add(updateDescription(context.getString(R.string.MessageRecord_you_accepted_invite)));
         } else {
-          updates.add(context.getString(R.string.MessageRecord_you_added_invited_member_s, describe(uuid)));
+          updates.add(updateDescription(uuid, newPromotedMember -> context.getString(R.string.MessageRecord_you_added_invited_member_s, newPromotedMember)));
         }
       } else {
         if (newMemberIsYou) {
-          updates.add(context.getString(R.string.MessageRecord_s_added_you, describe(change.getEditor())));
+          updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_added_you, editor)));
         } else {
           if (uuid.equals(change.getEditor())) {
-            updates.add(context.getString(R.string.MessageRecord_s_accepted_invite, describe(uuid)));
+            updates.add(updateDescription(uuid, newAcceptedMember -> context.getString(R.string.MessageRecord_s_accepted_invite, newAcceptedMember)));
           } else {
-            updates.add(context.getString(R.string.MessageRecord_s_added_invited_member_s, describe(change.getEditor()), describe(uuid)));
+            updates.add(updateDescription(change.getEditor(), uuid, (editor, newAcceptedMember) -> context.getString(R.string.MessageRecord_s_added_invited_member_s, editor, newAcceptedMember)));
           }
         }
       }
     }
   }
 
-  private void describeUnknownEditorPromotePending(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorPromotePending(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     for (DecryptedMember newMember : change.getPromotePendingMembersList()) {
       ByteString uuid = newMember.getUuid();
       boolean newMemberIsYou = uuid.equals(selfUuidBytes);
 
       if (newMemberIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_you_joined_the_group));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_you_joined_the_group)));
       } else {
-        updates.add(context.getString(R.string.MessageRecord_s_joined_the_group, describe(uuid)));
+        updates.add(updateDescription(uuid, newMemberName -> context.getString(R.string.MessageRecord_s_joined_the_group, newMemberName)));
       }
     }
   }
 
-  private void describeNewTitle(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeNewTitle(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     if (change.hasNewTitle()) {
+      String newTitle = change.getNewTitle().getValue();
       if (editorIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_you_changed_the_group_name_to_s, change.getNewTitle().getValue()));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_you_changed_the_group_name_to_s, newTitle)));
       } else {
-        updates.add(context.getString(R.string.MessageRecord_s_changed_the_group_name_to_s, describe(change.getEditor()), change.getNewTitle().getValue()));
+        updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_changed_the_group_name_to_s, editor, newTitle)));
       }
     }
   }
 
-  private void describeUnknownEditorNewTitle(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorNewTitle(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     if (change.hasNewTitle()) {
-      updates.add(context.getString(R.string.MessageRecord_the_group_name_has_changed_to_s, change.getNewTitle().getValue()));
+      updates.add(updateDescription(context.getString(R.string.MessageRecord_the_group_name_has_changed_to_s, change.getNewTitle().getValue())));
     }
   }
 
-  private void describeNewAvatar(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeNewAvatar(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     if (change.hasNewAvatar()) {
       if (editorIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_you_changed_the_group_avatar));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_you_changed_the_group_avatar)));
       } else {
-        updates.add(context.getString(R.string.MessageRecord_s_changed_the_group_avatar, describe(change.getEditor())));
+        updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_changed_the_group_avatar, editor)));
       }
     }
   }
 
-  private void describeUnknownEditorNewAvatar(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorNewAvatar(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     if (change.hasNewAvatar()) {
-      updates.add(context.getString(R.string.MessageRecord_the_group_group_avatar_has_been_changed));
+      updates.add(updateDescription(context.getString(R.string.MessageRecord_the_group_group_avatar_has_been_changed)));
     }
   }
 
-  private void describeNewTimer(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeNewTimer(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     if (change.hasNewTimer()) {
       String time = ExpirationUtil.getExpirationDisplayValue(context, change.getNewTimer().getDuration());
       if (editorIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_you_set_disappearing_message_time_to_s, time));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_you_set_disappearing_message_time_to_s, time)));
       } else {
-        updates.add(context.getString(R.string.MessageRecord_s_set_disappearing_message_time_to_s, describe(change.getEditor()), time));
+        updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_set_disappearing_message_time_to_s, editor, time)));
       }
     }
   }
 
-  private void describeUnknownEditorNewTimer(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorNewTimer(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     if (change.hasNewTimer()) {
       String time = ExpirationUtil.getExpirationDisplayValue(context, change.getNewTimer().getDuration());
-      updates.add(context.getString(R.string.MessageRecord_disappearing_message_time_set_to_s, time));
+      updates.add(updateDescription(context.getString(R.string.MessageRecord_disappearing_message_time_set_to_s, time)));
     }
   }
 
-  private void describeNewAttributeAccess(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeNewAttributeAccess(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     if (change.getNewAttributeAccess() != AccessControl.AccessRequired.UNKNOWN) {
       String accessLevel = GV2AccessLevelUtil.toString(context, change.getNewAttributeAccess());
       if (editorIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_you_changed_who_can_edit_group_info_to_s, accessLevel));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_you_changed_who_can_edit_group_info_to_s, accessLevel)));
       } else {
-        updates.add(context.getString(R.string.MessageRecord_s_changed_who_can_edit_group_info_to_s, describe(change.getEditor()), accessLevel));
+        updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_changed_who_can_edit_group_info_to_s, editor, accessLevel)));
       }
     }
   }
 
-  private void describeUnknownEditorNewAttributeAccess(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorNewAttributeAccess(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     if (change.getNewAttributeAccess() != AccessControl.AccessRequired.UNKNOWN) {
       String accessLevel = GV2AccessLevelUtil.toString(context, change.getNewAttributeAccess());
-      updates.add(context.getString(R.string.MessageRecord_who_can_edit_group_info_has_been_changed_to_s, accessLevel));
+      updates.add(updateDescription(context.getString(R.string.MessageRecord_who_can_edit_group_info_has_been_changed_to_s, accessLevel)));
     }
   }
 
-  private void describeNewMembershipAccess(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeNewMembershipAccess(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     boolean editorIsYou = change.getEditor().equals(selfUuidBytes);
 
     if (change.getNewMemberAccess() != AccessControl.AccessRequired.UNKNOWN) {
       String accessLevel = GV2AccessLevelUtil.toString(context, change.getNewMemberAccess());
       if (editorIsYou) {
-        updates.add(context.getString(R.string.MessageRecord_you_changed_who_can_edit_group_membership_to_s, accessLevel));
+        updates.add(updateDescription(context.getString(R.string.MessageRecord_you_changed_who_can_edit_group_membership_to_s, accessLevel)));
       } else {
-        updates.add(context.getString(R.string.MessageRecord_s_changed_who_can_edit_group_membership_to_s, describe(change.getEditor()), accessLevel));
+        updates.add(updateDescription(change.getEditor(), editor -> context.getString(R.string.MessageRecord_s_changed_who_can_edit_group_membership_to_s, editor, accessLevel)));
       }
     }
   }
 
-  private void describeUnknownEditorNewMembershipAccess(@NonNull DecryptedGroupChange change, @NonNull List<String> updates) {
+  private void describeUnknownEditorNewMembershipAccess(@NonNull DecryptedGroupChange change, @NonNull List<UpdateDescription> updates) {
     if (change.getNewMemberAccess() != AccessControl.AccessRequired.UNKNOWN) {
       String accessLevel = GV2AccessLevelUtil.toString(context, change.getNewMemberAccess());
-      updates.add(context.getString(R.string.MessageRecord_who_can_edit_group_membership_has_been_changed_to_s, accessLevel));
+      updates.add(updateDescription(context.getString(R.string.MessageRecord_who_can_edit_group_membership_has_been_changed_to_s, accessLevel)));
     }
   }
 
-  private @NonNull String describe(@NonNull ByteString uuid) {
-    return descriptionStrategy.describe(UuidUtil.fromByteString(uuid));
-  }
-
   interface DescribeMemberStrategy {
 
     /**
      * Map a UUID to a string that describes the group member.
      */
-    @NonNull String describe(@NonNull UUID uuid);
+    @NonNull
+    @WorkerThread
+    String describe(@NonNull UUID uuid);
+  }
+
+  private interface StringFactory1Arg {
+    String create(String arg1);
+  }
+
+  private interface StringFactory2Args {
+    String create(String arg1, String arg2);
+  }
+
+  private static UpdateDescription updateDescription(@NonNull String string) {
+    return UpdateDescription.staticDescription(string);
+  }
+
+  private UpdateDescription updateDescription(@NonNull ByteString uuid1Bytes, @NonNull StringFactory1Arg stringFactory) {
+    UUID uuid1 = UuidUtil.fromByteStringOrUnknown(uuid1Bytes);
+
+    return UpdateDescription.mentioning(Collections.singletonList(uuid1), () -> stringFactory.create(descriptionStrategy.describe(uuid1)));
+  }
+
+  private UpdateDescription updateDescription(@NonNull ByteString uuid1Bytes, @NonNull ByteString uuid2Bytes, @NonNull StringFactory2Args stringFactory) {
+    UUID uuid1 = UuidUtil.fromByteStringOrUnknown(uuid1Bytes);
+    UUID uuid2 = UuidUtil.fromByteStringOrUnknown(uuid2Bytes);
+
+    return UpdateDescription.mentioning(Arrays.asList(uuid1, uuid2), () -> stringFactory.create(descriptionStrategy.describe(uuid1), descriptionStrategy.describe(uuid2)));
   }
 }

app/src/main/java/org/thoughtcrime/securesms/database/model/LiveUpdateMessage.java

@@ -0,0 +1,47 @@
+package org.thoughtcrime.securesms.database.model;
+
+import androidx.annotation.AnyThread;
+import androidx.annotation.NonNull;
+import androidx.lifecycle.LiveData;
+
+import com.annimon.stream.Stream;
+
+import org.thoughtcrime.securesms.recipients.Recipient;
+import org.thoughtcrime.securesms.recipients.RecipientId;
+import org.thoughtcrime.securesms.util.livedata.LiveDataUtil;
+import org.whispersystems.libsignal.util.guava.Function;
+
+import java.util.List;
+
+public final class LiveUpdateMessage {
+
+  /**
+   * Creates a live data that observes the recipients mentioned in the {@link UpdateDescription} and
+   * recreates the string asynchronously when they change.
+   */
+  @AnyThread
+  public static LiveData<String> fromMessageDescription(@NonNull UpdateDescription updateDescription) {
+    if (updateDescription.isStringStatic()) {
+      return LiveDataUtil.just(updateDescription.getStaticString());
+    }
+
+    List<LiveData<Recipient>> allMentionedRecipients = Stream.of(updateDescription.getMentioned())
+                                                             .map(uuid -> Recipient.resolved(RecipientId.from(uuid, null)).live().getLiveData())
+                                                             .toList();
+
+    LiveData<?> mentionedRecipientChangeStream = allMentionedRecipients.isEmpty() ? LiveDataUtil.just(new Object())
+                                                                                  : LiveDataUtil.merge(allMentionedRecipients);
+
+    return LiveDataUtil.mapAsync(mentionedRecipientChangeStream, event -> updateDescription.getString());
+  }
+
+  /**
+   * Observes a single recipient and recreates the string asynchronously when they change.
+   */
+  public static LiveData<String> recipientToStringAsync(@NonNull RecipientId recipientId,
+                                                        @NonNull Function<Recipient, String> createStringInBackground)
+  {
+    return LiveDataUtil.mapAsync(Recipient.live(recipientId).getLiveData(), createStringInBackground);
+  }
+
+}

app/src/main/java/org/thoughtcrime/securesms/database/model/MessageRecord.java

@@ -23,8 +23,8 @@ import android.text.style.RelativeSizeSpan;
 import android.text.style.StyleSpan;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
-import org.signal.storageservice.protos.groups.local.DecryptedGroupChange;
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.database.MmsSmsColumns;
 import org.thoughtcrime.securesms.database.SmsDatabase;
@@ -39,9 +39,11 @@ import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.util.Base64;
 import org.thoughtcrime.securesms.util.ExpirationUtil;
 import org.thoughtcrime.securesms.util.GroupUtil;
+import org.whispersystems.libsignal.util.guava.Function;
 import org.whispersystems.signalservice.api.util.UuidUtil;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.List;
 import java.util.UUID;
 
@@ -109,78 +111,84 @@ public abstract class MessageRecord extends DisplayRecord {
 
   @Override
   public SpannableString getDisplayBody(@NonNull Context context) {
-    if (isGroupUpdate() && isGroupV2()) {
+    UpdateDescription updateDisplayBody = getUpdateDisplayBody(context);
-      return new SpannableString(getGv2Description(context));
+
-    } else if (isGroupUpdate() && isOutgoing()) {
+    if (updateDisplayBody != null) {
-      return new SpannableString(context.getString(R.string.MessageRecord_you_updated_group));
+      return new SpannableString(updateDisplayBody.getString());
-    } else if (isGroupUpdate()) {
-      return new SpannableString(GroupUtil.getDescription(context, getBody(), false).toString(getIndividualRecipient()));
-    } else if (isGroupQuit() && isOutgoing()) {
-      return new SpannableString(context.getString(R.string.MessageRecord_left_group));
-    } else if (isGroupQuit()) {
-      return new SpannableString(context.getString(R.string.ConversationItem_group_action_left, getIndividualRecipient().getDisplayName(context)));
-    } else if (isIncomingCall()) {
-      return new SpannableString(context.getString(R.string.MessageRecord_s_called_you, getIndividualRecipient().getDisplayName(context)));
-    } else if (isOutgoingCall()) {
-      return new SpannableString(context.getString(R.string.MessageRecord_you_called));
-    } else if (isMissedCall()) {
-      return new SpannableString(context.getString(R.string.MessageRecord_missed_call));
-    } else if (isJoined()) {
-      return new SpannableString(context.getString(R.string.MessageRecord_s_joined_signal, getIndividualRecipient().getDisplayName(context)));
-    } else if (isExpirationTimerUpdate()) {
-      int seconds = (int)(getExpiresIn() / 1000);
-      if (seconds <= 0) {
-        return isOutgoing() ? new SpannableString(context.getString(R.string.MessageRecord_you_disabled_disappearing_messages))
-                            : new SpannableString(context.getString(R.string.MessageRecord_s_disabled_disappearing_messages, getIndividualRecipient().getDisplayName(context)));
-      }
-      String time = ExpirationUtil.getExpirationDisplayValue(context, seconds);
-      return isOutgoing() ? new SpannableString(context.getString(R.string.MessageRecord_you_set_disappearing_message_time_to_s, time))
-                          : new SpannableString(context.getString(R.string.MessageRecord_s_set_disappearing_message_time_to_s, getIndividualRecipient().getDisplayName(context), time));
-    } else if (isIdentityUpdate()) {
-      return new SpannableString(context.getString(R.string.MessageRecord_your_safety_number_with_s_has_changed, getIndividualRecipient().getDisplayName(context)));
-    } else if (isIdentityVerified()) {
-      if (isOutgoing()) return new SpannableString(context.getString(R.string.MessageRecord_you_marked_your_safety_number_with_s_verified, getIndividualRecipient().getDisplayName(context)));
-      else              return new SpannableString(context.getString(R.string.MessageRecord_you_marked_your_safety_number_with_s_verified_from_another_device, getIndividualRecipient().getDisplayName(context)));
-    } else if (isIdentityDefault()) {
-      if (isOutgoing()) return new SpannableString(context.getString(R.string.MessageRecord_you_marked_your_safety_number_with_s_unverified, getIndividualRecipient().getDisplayName(context)));
-      else              return new SpannableString(context.getString(R.string.MessageRecord_you_marked_your_safety_number_with_s_unverified_from_another_device, getIndividualRecipient().getDisplayName(context)));
-    } else if (isProfileChange()) {
-      return new SpannableString(getProfileChangeDescription(context));
     }
 
     return new SpannableString(getBody());
   }
 
-  private @NonNull String getGv2Description(@NonNull Context context) {
+  public @Nullable UpdateDescription getUpdateDisplayBody(@NonNull Context context) {
-    if (!isGroupUpdate() || !isGroupV2()) {
+    if (isGroupUpdate() && isGroupV2()) {
-      throw new AssertionError();
+      return getGv2ChangeDescription(context, getBody());
+    } else if (isGroupUpdate() && isOutgoing()) {
+      return staticUpdateDescription(context.getString(R.string.MessageRecord_you_updated_group));
+    } else if (isGroupUpdate()) {
+      return fromRecipient(getIndividualRecipient(), r -> GroupUtil.getNonV2GroupDescription(context, getBody()).toString(r));
+    } else if (isGroupQuit() && isOutgoing()) {
+      return staticUpdateDescription(context.getString(R.string.MessageRecord_left_group));
+    } else if (isGroupQuit()) {
+      return fromRecipient(getIndividualRecipient(), r -> context.getString(R.string.ConversationItem_group_action_left, r.getDisplayName(context)));
+    } else if (isIncomingCall()) {
+      return fromRecipient(getIndividualRecipient(), r -> context.getString(R.string.MessageRecord_s_called_you, r.getDisplayName(context)));
+    } else if (isOutgoingCall()) {
+      return staticUpdateDescription(context.getString(R.string.MessageRecord_you_called));
+    } else if (isMissedCall()) {
+      return staticUpdateDescription(context.getString(R.string.MessageRecord_missed_call));
+    } else if (isJoined()) {
+      return staticUpdateDescription(context.getString(R.string.MessageRecord_s_joined_signal, getIndividualRecipient().getDisplayName(context)));
+    } else if (isExpirationTimerUpdate()) {
+      int seconds = (int)(getExpiresIn() / 1000);
+      if (seconds <= 0) {
+        return isOutgoing() ? staticUpdateDescription(context.getString(R.string.MessageRecord_you_disabled_disappearing_messages))
+                            : fromRecipient(getIndividualRecipient(), r -> context.getString(R.string.MessageRecord_s_disabled_disappearing_messages, r.getDisplayName(context)));
       }
+      String time = ExpirationUtil.getExpirationDisplayValue(context, seconds);
+      return isOutgoing() ? staticUpdateDescription(context.getString(R.string.MessageRecord_you_set_disappearing_message_time_to_s, time))
+                          : fromRecipient(getIndividualRecipient(), r -> context.getString(R.string.MessageRecord_s_set_disappearing_message_time_to_s, r.getDisplayName(context), time));
+    } else if (isIdentityUpdate()) {
+      return fromRecipient(getIndividualRecipient(), r -> context.getString(R.string.MessageRecord_your_safety_number_with_s_has_changed, r.getDisplayName(context)));
+    } else if (isIdentityVerified()) {
+      if (isOutgoing()) return fromRecipient(getIndividualRecipient(), r -> context.getString(R.string.MessageRecord_you_marked_your_safety_number_with_s_verified, r.getDisplayName(context)));
+      else              return fromRecipient(getIndividualRecipient(), r -> context.getString(R.string.MessageRecord_you_marked_your_safety_number_with_s_verified_from_another_device, r.getDisplayName(context)));
+    } else if (isIdentityDefault()) {
+      if (isOutgoing()) return fromRecipient(getIndividualRecipient(), r -> context.getString(R.string.MessageRecord_you_marked_your_safety_number_with_s_unverified, r.getDisplayName(context)));
+      else              return fromRecipient(getIndividualRecipient(), r -> context.getString(R.string.MessageRecord_you_marked_your_safety_number_with_s_unverified_from_another_device, r.getDisplayName(context)));
+    } else if (isProfileChange()) {
+      return staticUpdateDescription(getProfileChangeDescription(context));
+    }
+
+    return null;
+  }
+
+  public static @NonNull UpdateDescription getGv2ChangeDescription(@NonNull Context context, @NonNull String body) {
     try {
       ShortStringDescriptionStrategy descriptionStrategy     = new ShortStringDescriptionStrategy(context);
-      byte[]                         decoded                 = Base64.decode(getBody());
+      byte[]                         decoded                 = Base64.decode(body);
       DecryptedGroupV2Context        decryptedGroupV2Context = DecryptedGroupV2Context.parseFrom(decoded);
       GroupsV2UpdateMessageProducer  updateMessageProducer   = new GroupsV2UpdateMessageProducer(context, descriptionStrategy, Recipient.self().getUuid().get());
 
       if (decryptedGroupV2Context.hasChange() && decryptedGroupV2Context.getGroupState().getRevision() > 0) {
-        DecryptedGroupChange change  = decryptedGroupV2Context.getChange();
+        return UpdateDescription.concatWithNewLines(updateMessageProducer.describeChanges(decryptedGroupV2Context.getChange()));
-        List<String>         strings = updateMessageProducer.describeChange(change);
-        StringBuilder        result  = new StringBuilder();
-
-        for (int i = 0; i < strings.size(); i++) {
-          if (i > 0) result.append('\n');
-          result.append(strings.get(i));
-        }
-
-        return result.toString();
       } else {
         return updateMessageProducer.describeNewGroup(decryptedGroupV2Context.getGroupState());
       }
     } catch (IOException e) {
       Log.w(TAG, "GV2 Message update detail could not be read", e);
-      return context.getString(R.string.MessageRecord_group_updated);
+      return staticUpdateDescription(context.getString(R.string.MessageRecord_group_updated));
     }
   }
 
+  private static @NonNull UpdateDescription fromRecipient(@NonNull Recipient recipient, @NonNull Function<Recipient, String> stringFunction) {
+    return UpdateDescription.mentioning(Collections.singletonList(recipient.getUuid().or(UuidUtil.UNKNOWN_UUID)), () -> stringFunction.apply(recipient.resolve()));
+  }
+
+  private static @NonNull UpdateDescription staticUpdateDescription(@NonNull String string) {
+    return UpdateDescription.staticDescription(string);
+  }
+
   private @NonNull String getProfileChangeDescription(@NonNull Context context) {
     try {
       byte[]               decoded              = Base64.decode(getBody());
@@ -316,7 +324,7 @@ public abstract class MessageRecord extends DisplayRecord {
     return isFailed() && ((getRecipient().isPushGroup() && hasNetworkFailures()) || !isIdentityMismatchFailure());
   }
 
-  protected SpannableString emphasisAdded(String sequence) {
+  protected static SpannableString emphasisAdded(String sequence) {
     SpannableString spannable = new SpannableString(sequence);
     spannable.setSpan(new RelativeSizeSpan(0.9f), 0, sequence.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
     spannable.setSpan(new StyleSpan(android.graphics.Typeface.ITALIC), 0, sequence.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

app/src/main/java/org/thoughtcrime/securesms/database/model/UpdateDescription.java

@@ -0,0 +1,151 @@
+package org.thoughtcrime.securesms.database.model;
+
+import androidx.annotation.AnyThread;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.WorkerThread;
+
+import org.thoughtcrime.securesms.util.Util;
+import org.whispersystems.signalservice.api.util.UuidUtil;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.UUID;
+
+/**
+ * Contains a list of people mentioned in an update message and a function to create the update message.
+ */
+public final class UpdateDescription {
+
+  public interface StringFactory {
+    @WorkerThread
+    String create();
+  }
+
+  private final Collection<UUID> mentioned;
+  private final StringFactory    stringFactory;
+  private final String           staticString;
+
+  private UpdateDescription(@NonNull Collection<UUID> mentioned,
+                            @Nullable StringFactory stringFactory,
+                            @Nullable String staticString)
+  {
+    if (staticString == null && stringFactory == null) {
+      throw new AssertionError();
+    }
+    this.mentioned     = mentioned;
+    this.stringFactory = stringFactory;
+    this.staticString  = staticString;
+  }
+
+  /**
+   * Create an update description which has a string value created by a supplied factory method that
+   * will be run on a background thread.
+   *
+   * @param mentioned     UUIDs of recipients that are mentioned in the string.
+   * @param stringFactory The background method for generating the string.
+   */
+  public static UpdateDescription mentioning(@NonNull Collection<UUID> mentioned,
+                                             @NonNull StringFactory stringFactory)
+  {
+    return new UpdateDescription(UuidUtil.filterKnown(mentioned),
+                                 stringFactory,
+                                 null);
+  }
+
+  /**
+   * Create an update description that's string value is fixed.
+   */
+  public static UpdateDescription staticDescription(@NonNull String staticString) {
+    return new UpdateDescription(Collections.emptyList(), null, staticString);
+  }
+
+  public boolean isStringStatic() {
+    return staticString != null;
+  }
+
+  @AnyThread
+  public @NonNull String getStaticString() {
+    if (staticString == null) {
+      throw new UnsupportedOperationException();
+    }
+
+    return staticString;
+  }
+
+  @WorkerThread
+  public @NonNull String getString() {
+    if (staticString != null) {
+      return staticString;
+    }
+
+    Util.assertNotMainThread();
+
+    //noinspection ConstantConditions
+    return stringFactory.create();
+  }
+
+  @AnyThread
+  public Collection<UUID> getMentioned() {
+    return mentioned;
+  }
+
+  public static UpdateDescription concatWithNewLines(@NonNull List<UpdateDescription> updateDescriptions) {
+    if (updateDescriptions.size() == 0) {
+      throw new AssertionError();
+    }
+
+    if (updateDescriptions.size() == 1) {
+      return updateDescriptions.get(0);
+    }
+
+    if (allAreStatic(updateDescriptions)) {
+      return UpdateDescription.staticDescription(concatStaticLines(updateDescriptions));
+    }
+
+    Set<UUID> allMentioned = new HashSet<>();
+
+    for (UpdateDescription updateDescription : updateDescriptions) {
+      allMentioned.addAll(updateDescription.getMentioned());
+    }
+
+    return UpdateDescription.mentioning(allMentioned, () -> concatLines(updateDescriptions));
+  }
+
+  private static boolean allAreStatic(@NonNull Collection<UpdateDescription> updateDescriptions) {
+    for (UpdateDescription description : updateDescriptions) {
+      if (!description.isStringStatic()) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  @WorkerThread
+  private static String concatLines(@NonNull List<UpdateDescription> updateDescriptions) {
+    StringBuilder result = new StringBuilder();
+
+    for (int i = 0; i < updateDescriptions.size(); i++) {
+      if (i > 0) result.append('\n');
+      result.append(updateDescriptions.get(i).getString());
+    }
+
+    return result.toString();
+  }
+
+  @AnyThread
+  private static String concatStaticLines(@NonNull List<UpdateDescription> updateDescriptions) {
+    StringBuilder result = new StringBuilder();
+
+    for (int i = 0; i < updateDescriptions.size(); i++) {
+      if (i > 0) result.append('\n');
+      result.append(updateDescriptions.get(i).getStaticString());
+    }
+
+    return result.toString();
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/util/GroupUtil.java

@@ -14,7 +14,6 @@ import org.thoughtcrime.securesms.groups.GroupId;
 import org.thoughtcrime.securesms.logging.Log;
 import org.thoughtcrime.securesms.mms.MessageGroupContext;
 import org.thoughtcrime.securesms.recipients.Recipient;
-import org.thoughtcrime.securesms.recipients.RecipientForeverObserver;
 import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.whispersystems.libsignal.util.guava.Optional;
 import org.whispersystems.signalservice.api.messages.SignalServiceDataMessage;
@@ -67,13 +66,13 @@ public final class GroupUtil {
     return Optional.absent();
   }
 
-  public static @NonNull GroupDescription getDescription(@NonNull Context context, @Nullable String encodedGroup, boolean isV2) {
+  public static @NonNull GroupDescription getNonV2GroupDescription(@NonNull Context context, @Nullable String encodedGroup) {
     if (encodedGroup == null) {
       return new GroupDescription(context, null);
     }
 
     try {
-      MessageGroupContext groupContext = new MessageGroupContext(encodedGroup, isV2);
+      MessageGroupContext groupContext = new MessageGroupContext(encodedGroup, false);
       return new GroupDescription(context, groupContext);
     } catch (IOException e) {
       Log.w(TAG, e);
@@ -117,7 +116,8 @@ public final class GroupUtil {
       }
     }
 
-    public String toString(Recipient sender) {
+    @WorkerThread
+    public String toString(@NonNull Recipient sender) {
       StringBuilder description = new StringBuilder();
       description.append(context.getString(R.string.MessageRecord_s_updated_group, sender.getDisplayName(context)));
 
@@ -142,22 +142,6 @@ public final class GroupUtil {
       return description.toString();
     }
 
-    public void addObserver(RecipientForeverObserver listener) {
-      if (this.members != null) {
-        for (RecipientId member : this.members) {
-          Recipient.live(member).observeForever(listener);
-        }
-      }
-    }
-
-    public void removeObserver(RecipientForeverObserver listener) {
-      if (this.members != null) {
-        for (RecipientId member : this.members) {
-          Recipient.live(member).removeForeverObserver(listener);
-        }
-      }
-    }
-
     private String toString(List<RecipientId> recipients) {
       StringBuilder result = new StringBuilder();
 

app/src/main/java/org/thoughtcrime/securesms/util/livedata/LiveDataUtil.java

@@ -11,6 +11,10 @@ import org.thoughtcrime.securesms.util.concurrent.SerialMonoLifoExecutor;
 import org.thoughtcrime.securesms.util.concurrent.SignalExecutors;
 import org.whispersystems.libsignal.util.guava.Function;
 
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Set;
 import java.util.concurrent.Executor;
 
 public final class LiveDataUtil {
@@ -78,6 +82,34 @@ public final class LiveDataUtil {
     return new CombineLiveData<>(a, b, combine);
   }
 
+  /**
+   * Merges the supplied live data streams.
+   */
+  public static <T> LiveData<T> merge(@NonNull List<LiveData<T>> liveDataList) {
+    Set<LiveData<T>> set = new LinkedHashSet<>(liveDataList);
+
+    set.addAll(liveDataList);
+
+    if (set.size() == 1) {
+      return liveDataList.get(0);
+    }
+
+    MediatorLiveData<T> mergedLiveData = new MediatorLiveData<>();
+
+    for (LiveData<T> liveDataSource : set) {
+      mergedLiveData.addSource(liveDataSource, mergedLiveData::setValue);
+    }
+
+    return mergedLiveData;
+  }
+
+  /**
+   * @return Live data with just the initial value.
+   */
+  public static <T> LiveData<T> just(@NonNull T item) {
+    return new MutableLiveData<>(item);
+  }
+
   public interface Combine<A, B, R> {
     @NonNull R apply(@NonNull A a, @NonNull B b);
   }

app/src/main/res/layout/conversation_item_update.xml

@@ -41,7 +41,7 @@
 
 
     <LinearLayout
-        android:layout_width="wrap_content"
+        android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginBottom="7dp"
         android:gravity="center"
@@ -50,7 +50,7 @@
         <org.thoughtcrime.securesms.components.emoji.EmojiTextView
             android:id="@+id/conversation_update_body"
             style="@style/Signal.Text.Preview"
-            android:layout_width="wrap_content"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:autoLink="all"
             android:gravity="center"

app/src/test/java/org/thoughtcrime/securesms/database/model/GroupsV2UpdateMessageProducerTest.java

@@ -5,11 +5,16 @@ import android.app.Application;
 import androidx.annotation.NonNull;
 import androidx.test.core.app.ApplicationProvider;
 
+import com.annimon.stream.Stream;
 import com.google.common.collect.ImmutableMap;
 
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.powermock.core.classloader.annotations.PowerMockIgnore;
+import org.powermock.core.classloader.annotations.PrepareForTest;
+import org.powermock.modules.junit4.rule.PowerMockRule;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
 import org.signal.storageservice.protos.groups.AccessControl;
@@ -22,19 +27,27 @@ import org.signal.storageservice.protos.groups.local.DecryptedPendingMember;
 import org.signal.storageservice.protos.groups.local.DecryptedPendingMemberRemoval;
 import org.signal.storageservice.protos.groups.local.DecryptedString;
 import org.signal.storageservice.protos.groups.local.DecryptedTimer;
+import org.thoughtcrime.securesms.testutil.MainThreadUtil;
+import org.thoughtcrime.securesms.util.Util;
 import org.whispersystems.signalservice.api.util.UuidUtil;
 
 import java.util.Arrays;
+import java.util.List;
 import java.util.Map;
 import java.util.UUID;
 
+import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
 
 @RunWith(RobolectricTestRunner.class)
 @Config(manifest = Config.NONE, application = Application.class)
+@PowerMockIgnore({ "org.mockito.*", "org.robolectric.*", "android.*", "androidx.*" })
+@PrepareForTest(Util.class)
 public final class GroupsV2UpdateMessageProducerTest {
 
   private UUID you;
@@ -43,6 +56,9 @@ public final class GroupsV2UpdateMessageProducerTest {
 
   private GroupsV2UpdateMessageProducer producer;
 
+  @Rule
+  public PowerMockRule powerMockRule = new PowerMockRule();
+
   @Before
   public void setup() {
     you   = UUID.randomUUID();
@@ -57,7 +73,7 @@ public final class GroupsV2UpdateMessageProducerTest {
     DecryptedGroupChange change = changeBy(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice updated the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice updated the group.")));
   }
 
   @Test
@@ -65,7 +81,7 @@ public final class GroupsV2UpdateMessageProducerTest {
     DecryptedGroupChange change = changeBy(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You updated the group.")));
+    assertThat(describeChange(change), is(singletonList("You updated the group.")));
   }
 
   @Test
@@ -73,7 +89,7 @@ public final class GroupsV2UpdateMessageProducerTest {
     DecryptedGroupChange change = changeByUnknown()
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("The group was updated.")));
+    assertThat(describeChange(change), is(singletonList("The group was updated.")));
   }
 
   // Member additions
@@ -84,7 +100,16 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .addMember(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice added Bob.")));
+    assertThat(describeChange(change), is(singletonList("Alice added Bob.")));
+  }
+
+  @Test
+  public void member_added_member_mentions_both() {
+    DecryptedGroupChange change = changeBy(alice)
+                                    .addMember(bob)
+                                    .build();
+
+    assertSingleChangeMentioning(change, Arrays.asList(alice, bob));
   }
 
   @Test
@@ -93,7 +118,16 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .addMember(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You added Bob.")));
+    assertThat(describeChange(change), is(singletonList("You added Bob.")));
+  }
+
+  @Test
+  public void you_added_member_mentions_just_member() {
+    DecryptedGroupChange change = changeBy(you)
+                                    .addMember(bob)
+                                    .build();
+
+    assertSingleChangeMentioning(change, singletonList(bob));
   }
 
   @Test
@@ -102,7 +136,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .addMember(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice added you to the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice added you to the group.")));
   }
 
   @Test
@@ -111,7 +145,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .addMember(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You joined the group.")));
+    assertThat(describeChange(change), is(singletonList("You joined the group.")));
   }
 
   @Test
@@ -120,7 +154,16 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .addMember(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob joined the group.")));
+    assertThat(describeChange(change), is(singletonList("Bob joined the group.")));
+  }
+
+  @Test
+  public void member_added_themselves_mentions_just_member() {
+    DecryptedGroupChange change = changeBy(bob)
+                                    .addMember(bob)
+                                    .build();
+
+    assertSingleChangeMentioning(change, singletonList(bob));
   }
 
   @Test
@@ -129,7 +172,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .addMember(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You joined the group.")));
+    assertThat(describeChange(change), is(singletonList("You joined the group.")));
   }
 
   @Test
@@ -138,18 +181,18 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .addMember(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob joined the group.")));
+    assertThat(describeChange(change), is(singletonList("Bob joined the group.")));
   }
 
-  // Member removals
 
+  // Member removals
   @Test
   public void member_removed_member() {
     DecryptedGroupChange change = changeBy(alice)
                                     .deleteMember(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice removed Bob.")));
+    assertThat(describeChange(change), is(singletonList("Alice removed Bob.")));
   }
 
   @Test
@@ -158,7 +201,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .deleteMember(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You removed Bob.")));
+    assertThat(describeChange(change), is(singletonList("You removed Bob.")));
   }
 
   @Test
@@ -167,7 +210,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .deleteMember(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice removed you from the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice removed you from the group.")));
   }
 
   @Test
@@ -176,7 +219,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .deleteMember(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You left the group.")));
+    assertThat(describeChange(change), is(singletonList("You left the group.")));
   }
 
   @Test
@@ -185,7 +228,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .deleteMember(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob left the group.")));
+    assertThat(describeChange(change), is(singletonList("Bob left the group.")));
   }
 
   @Test
@@ -194,7 +237,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .deleteMember(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice is no longer in the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice is no longer in the group.")));
   }
 
   @Test
@@ -203,7 +246,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .deleteMember(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You are no longer in the group.")));
+    assertThat(describeChange(change), is(singletonList("You are no longer in the group.")));
   }
 
   // Member role modifications
@@ -214,7 +257,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promoteToAdmin(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You made Alice an admin.")));
+    assertThat(describeChange(change), is(singletonList("You made Alice an admin.")));
   }
 
   @Test
@@ -223,7 +266,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promoteToAdmin(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob made Alice an admin.")));
+    assertThat(describeChange(change), is(singletonList("Bob made Alice an admin.")));
   }
 
   @Test
@@ -232,7 +275,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promoteToAdmin(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice made you an admin.")));
+    assertThat(describeChange(change), is(singletonList("Alice made you an admin.")));
   }
 
   @Test
@@ -241,7 +284,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .demoteToMember(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You revoked admin privileges from Bob.")));
+    assertThat(describeChange(change), is(singletonList("You revoked admin privileges from Bob.")));
   }
 
   @Test
@@ -250,7 +293,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .demoteToMember(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob revoked admin privileges from Alice.")));
+    assertThat(describeChange(change), is(singletonList("Bob revoked admin privileges from Alice.")));
   }
 
   @Test
@@ -259,7 +302,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .demoteToMember(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice revoked your admin privileges.")));
+    assertThat(describeChange(change), is(singletonList("Alice revoked your admin privileges.")));
   }
 
   @Test
@@ -268,7 +311,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promoteToAdmin(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice is now an admin.")));
+    assertThat(describeChange(change), is(singletonList("Alice is now an admin.")));
   }
 
   @Test
@@ -277,7 +320,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promoteToAdmin(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You are now an admin.")));
+    assertThat(describeChange(change), is(singletonList("You are now an admin.")));
   }
 
   @Test
@@ -286,7 +329,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .demoteToMember(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice is no longer an admin.")));
+    assertThat(describeChange(change), is(singletonList("Alice is no longer an admin.")));
   }
 
   @Test
@@ -295,7 +338,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .demoteToMember(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You are no longer an admin.")));
+    assertThat(describeChange(change), is(singletonList("You are no longer an admin.")));
   }
 
   // Member invitation
@@ -306,7 +349,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .invite(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You invited Alice to the group.")));
+    assertThat(describeChange(change), is(singletonList("You invited Alice to the group.")));
   }
 
   @Test
@@ -315,7 +358,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .invite(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice invited you to the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice invited you to the group.")));
   }
 
   @Test
@@ -324,7 +367,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .invite(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice invited 1 person to the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice invited 1 person to the group.")));
   }
 
   @Test
@@ -334,7 +377,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .invite(UUID.randomUUID())
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice invited 2 people to the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice invited 2 people to the group.")));
   }
 
   @Test
@@ -346,7 +389,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .invite(UUID.randomUUID())
                                     .build();
 
-    assertThat(producer.describeChange(change), is(Arrays.asList("Bob invited you to the group.", "Bob invited 3 people to the group.")));
+    assertThat(describeChange(change), is(Arrays.asList("Bob invited you to the group.", "Bob invited 3 people to the group.")));
   }
 
   @Test
@@ -355,7 +398,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .invite(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You were invited to the group.")));
+    assertThat(describeChange(change), is(singletonList("You were invited to the group.")));
   }
 
   @Test
@@ -364,7 +407,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .invite(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("1 person was invited to the group.")));
+    assertThat(describeChange(change), is(singletonList("1 person was invited to the group.")));
   }
 
   @Test
@@ -374,7 +417,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .invite(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("2 people were invited to the group.")));
+    assertThat(describeChange(change), is(singletonList("2 people were invited to the group.")));
   }
 
   @Test
@@ -386,7 +429,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .invite(UUID.randomUUID())
                                     .build();
 
-    assertThat(producer.describeChange(change), is(Arrays.asList("You were invited to the group.", "3 people were invited to the group.")));
+    assertThat(describeChange(change), is(Arrays.asList("You were invited to the group.", "3 people were invited to the group.")));
   }
 
   // Member invitation revocation
@@ -397,7 +440,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice revoked an invitation to the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice revoked an invitation to the group.")));
   }
 
   @Test
@@ -407,7 +450,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(UUID.randomUUID())
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice revoked 2 invitations to the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice revoked 2 invitations to the group.")));
   }
 
   @Test
@@ -416,7 +459,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You revoked an invitation to the group.")));
+    assertThat(describeChange(change), is(singletonList("You revoked an invitation to the group.")));
   }
 
   @Test
@@ -426,7 +469,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(UUID.randomUUID())
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You revoked 2 invitations to the group.")));
+    assertThat(describeChange(change), is(singletonList("You revoked 2 invitations to the group.")));
   }
 
   @Test
@@ -435,7 +478,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Someone declined an invitation to the group.")));
+    assertThat(describeChange(change), is(singletonList("Someone declined an invitation to the group.")));
   }
 
   @Test
@@ -444,7 +487,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You declined the invitation to the group.")));
+    assertThat(describeChange(change), is(singletonList("You declined the invitation to the group.")));
   }
 
   @Test
@@ -453,7 +496,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Your invitation to the group was revoked.")));
+    assertThat(describeChange(change), is(singletonList("Your invitation to the group was revoked.")));
   }
 
   @Test
@@ -462,7 +505,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("An invitation to the group was revoked.")));
+    assertThat(describeChange(change), is(singletonList("An invitation to the group was revoked.")));
   }
 
   @Test
@@ -472,7 +515,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(UUID.randomUUID())
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("2 invitations to the group were revoked.")));
+    assertThat(describeChange(change), is(singletonList("2 invitations to the group were revoked.")));
   }
 
   @Test
@@ -484,7 +527,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .uninvite(UUID.randomUUID())
                                     .build();
 
-    assertThat(producer.describeChange(change), is(Arrays.asList("Your invitation to the group was revoked.", "3 invitations to the group were revoked.")));
+    assertThat(describeChange(change), is(Arrays.asList("Your invitation to the group was revoked.", "3 invitations to the group were revoked.")));
   }
 
   // Promote pending members
@@ -495,7 +538,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promote(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob accepted an invitation to the group.")));
+    assertThat(describeChange(change), is(singletonList("Bob accepted an invitation to the group.")));
   }
 
   @Test
@@ -504,7 +547,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promote(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You accepted the invitation to the group.")));
+    assertThat(describeChange(change), is(singletonList("You accepted the invitation to the group.")));
   }
 
   @Test
@@ -513,7 +556,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promote(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob added invited member Alice.")));
+    assertThat(describeChange(change), is(singletonList("Bob added invited member Alice.")));
   }
 
   @Test
@@ -522,7 +565,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promote(bob)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You added invited member Bob.")));
+    assertThat(describeChange(change), is(singletonList("You added invited member Bob.")));
   }
 
   @Test
@@ -531,7 +574,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promote(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob added you to the group.")));
+    assertThat(describeChange(change), is(singletonList("Bob added you to the group.")));
   }
 
   @Test
@@ -540,7 +583,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promote(you)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You joined the group.")));
+    assertThat(describeChange(change), is(singletonList("You joined the group.")));
   }
 
   @Test
@@ -549,7 +592,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .promote(alice)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice joined the group.")));
+    assertThat(describeChange(change), is(singletonList("Alice joined the group.")));
   }
 
   // Title change
@@ -560,7 +603,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .title("New title")
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice changed the group name to \"New title\".")));
+    assertThat(describeChange(change), is(singletonList("Alice changed the group name to \"New title\".")));
   }
 
   @Test
@@ -569,7 +612,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .title("Title 2")
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You changed the group name to \"Title 2\".")));
+    assertThat(describeChange(change), is(singletonList("You changed the group name to \"Title 2\".")));
   }
 
   @Test
@@ -578,7 +621,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .title("Title 3")
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("The group name has changed to \"Title 3\".")));
+    assertThat(describeChange(change), is(singletonList("The group name has changed to \"Title 3\".")));
   }
   
   // Avatar change
@@ -589,7 +632,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .avatar("Avatar1")
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice changed the group avatar.")));
+    assertThat(describeChange(change), is(singletonList("Alice changed the group avatar.")));
   }
 
   @Test
@@ -598,7 +641,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .avatar("Avatar2")
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You changed the group avatar.")));
+    assertThat(describeChange(change), is(singletonList("You changed the group avatar.")));
   }
 
   @Test
@@ -607,7 +650,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .avatar("Avatar3")
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("The group avatar has been changed.")));
+    assertThat(describeChange(change), is(singletonList("The group avatar has been changed.")));
   }
 
   // Timer change
@@ -618,7 +661,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .timer(10)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob set the disappearing message timer to 10 seconds.")));
+    assertThat(describeChange(change), is(singletonList("Bob set the disappearing message timer to 10 seconds.")));
   }
 
   @Test
@@ -627,7 +670,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .timer(60)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You set the disappearing message timer to 1 minute.")));
+    assertThat(describeChange(change), is(singletonList("You set the disappearing message timer to 1 minute.")));
   }
 
   @Test
@@ -636,7 +679,16 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .timer(120)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("The disappearing message timer has been set to 2 minutes.")));
+    assertThat(describeChange(change), is(singletonList("The disappearing message timer has been set to 2 minutes.")));
+  }
+
+  @Test
+  public void unknown_change_timer_mentions_no_one() {
+    DecryptedGroupChange change = changeByUnknown()
+                                    .timer(120)
+                                    .build();
+
+    assertSingleChangeMentioning(change, emptyList());
   }
 
   // Attribute access change
@@ -647,7 +699,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .attributeAccess(AccessControl.AccessRequired.MEMBER)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Bob changed who can edit group info to \"All members\".")));
+    assertThat(describeChange(change), is(singletonList("Bob changed who can edit group info to \"All members\".")));
   }
 
   @Test
@@ -656,7 +708,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .attributeAccess(AccessControl.AccessRequired.ADMINISTRATOR)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You changed who can edit group info to \"Only admins\".")));
+    assertThat(describeChange(change), is(singletonList("You changed who can edit group info to \"Only admins\".")));
   }
 
   @Test
@@ -665,7 +717,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .attributeAccess(AccessControl.AccessRequired.ADMINISTRATOR)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Who can edit group info has been changed to \"Only admins\".")));
+    assertThat(describeChange(change), is(singletonList("Who can edit group info has been changed to \"Only admins\".")));
   }
 
   // Membership access change
@@ -676,7 +728,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .membershipAccess(AccessControl.AccessRequired.ADMINISTRATOR)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Alice changed who can edit group membership to \"Only admins\".")));
+    assertThat(describeChange(change), is(singletonList("Alice changed who can edit group membership to \"Only admins\".")));
   }
 
   @Test
@@ -685,7 +737,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .membershipAccess(AccessControl.AccessRequired.MEMBER)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("You changed who can edit group membership to \"All members\".")));
+    assertThat(describeChange(change), is(singletonList("You changed who can edit group membership to \"All members\".")));
   }
 
   @Test
@@ -694,7 +746,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .membershipAccess(AccessControl.AccessRequired.ADMINISTRATOR)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(singletonList("Who can edit group membership has been changed to \"Only admins\".")));
+    assertThat(describeChange(change), is(singletonList("Who can edit group membership has been changed to \"Only admins\".")));
   }
 
   // Multiple changes
@@ -708,7 +760,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .timer(300)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(Arrays.asList(
+    assertThat(describeChange(change), is(Arrays.asList(
       "Alice added Bob.",
       "Alice changed the group name to \"Title\".",
       "Alice set the disappearing message timer to 5 minutes.",
@@ -725,7 +777,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                                     .timer(600)
                                     .build();
 
-    assertThat(producer.describeChange(change), is(Arrays.asList(
+    assertThat(describeChange(change), is(Arrays.asList(
       "Bob joined the group.",
       "The group name has changed to \"Title 2\".",
       "The group avatar has been changed.",
@@ -740,7 +792,7 @@ public final class GroupsV2UpdateMessageProducerTest {
     DecryptedGroup group = newGroupBy(you, 0)
                              .build();
 
-    assertThat(producer.describeNewGroup(group), is("You created the group."));
+    assertThat(describeNewGroup(group), is("You created the group."));
   }
 
   @Test
@@ -749,7 +801,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                              .member(you)
                              .build();
 
-    assertThat(producer.describeNewGroup(group), is("Alice added you to the group."));
+    assertThat(describeNewGroup(group), is("Alice added you to the group."));
   }
 
   @Test
@@ -758,7 +810,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                              .member(you)
                              .build();
 
-    assertThat(producer.describeNewGroup(group), is("You joined the group."));
+    assertThat(describeNewGroup(group), is("You joined the group."));
   }
 
   @Test
@@ -767,7 +819,7 @@ public final class GroupsV2UpdateMessageProducerTest {
                              .invite(bob, you)
                              .build();
 
-    assertThat(producer.describeNewGroup(group), is("Bob invited you to the group."));
+    assertThat(describeNewGroup(group), is("Bob invited you to the group."));
   }
 
   @Test
@@ -775,13 +827,40 @@ public final class GroupsV2UpdateMessageProducerTest {
     DecryptedGroup group = newGroupBy(alice, 1)
                              .build();
 
-    assertThat(producer.describeNewGroup(group), is("Group updated."));
+    assertThat(describeNewGroup(group), is("Group updated."));
   } 
   
-  private GroupStateBuilder newGroupBy(UUID foundingMember, int revision) {
+  private @NonNull List<String> describeChange(@NonNull DecryptedGroupChange change) {
+    MainThreadUtil.setMainThread(false);
+    return Stream.of(producer.describeChanges(change))
+                 .map(UpdateDescription::getString)
+                 .toList();
+  }
+
+  private @NonNull String describeNewGroup(@NonNull DecryptedGroup group) {
+    MainThreadUtil.setMainThread(false);
+    return producer.describeNewGroup(group).getString();
+  }
+
+  private static GroupStateBuilder newGroupBy(UUID foundingMember, int revision) {
     return new GroupStateBuilder(foundingMember, revision);
   }
 
+  private void assertSingleChangeMentioning(DecryptedGroupChange change, List<UUID> expectedMentions) {
+    List<UpdateDescription> changes = producer.describeChanges(change);
+
+    assertThat(changes.size(), is(1));
+
+    UpdateDescription description = changes.get(0);
+    assertThat(description.getMentioned(), is(expectedMentions));
+
+    if (expectedMentions.isEmpty()) {
+      assertTrue(description.isStringStatic());
+    } else {
+      assertFalse(description.isStringStatic());
+    }
+  }
+
   private static class GroupStateBuilder {
 
     private final DecryptedGroup.Builder builder;

app/src/test/java/org/thoughtcrime/securesms/database/model/UpdateDescriptionTest.java

@@ -0,0 +1,168 @@
+package org.thoughtcrime.securesms.database.model;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.powermock.core.classloader.annotations.PrepareForTest;
+import org.powermock.modules.junit4.PowerMockRunner;
+import org.thoughtcrime.securesms.util.Util;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.thoughtcrime.securesms.testutil.MainThreadUtil.setMainThread;
+
+@RunWith(PowerMockRunner.class)
+@PrepareForTest(Util.class)
+public final class UpdateDescriptionTest {
+
+  @Before
+  public void setup() {
+    setMainThread(true);
+  }
+
+  @Test
+  public void staticDescription_byGetStaticString() {
+    UpdateDescription description = UpdateDescription.staticDescription("update");
+
+    assertEquals("update", description.getStaticString());
+  }
+
+  @Test
+  public void staticDescription_has_empty_mentions() {
+    UpdateDescription description = UpdateDescription.staticDescription("update");
+
+    assertTrue(description.getMentioned().isEmpty());
+  }
+
+  @Test
+  public void staticDescription_byString() {
+    UpdateDescription description = UpdateDescription.staticDescription("update");
+
+    assertEquals("update", description.getString());
+  }
+
+  @Test(expected = AssertionError.class)
+  public void stringFactory_cannot_run_on_main_thread() {
+    UpdateDescription description = UpdateDescription.mentioning(Collections.singletonList(UUID.randomUUID()), () -> "update");
+
+    setMainThread(true);
+
+    description.getString();
+  }
+
+  @Test(expected = UnsupportedOperationException.class)
+  public void stringFactory_cannot_call_static_string() {
+    UpdateDescription description = UpdateDescription.mentioning(Collections.singletonList(UUID.randomUUID()), () -> "update");
+
+    description.getStaticString();
+  }
+
+  @Test
+  public void stringFactory_not_evaluated_until_getString() {
+    AtomicInteger factoryCalls = new AtomicInteger();
+
+    UpdateDescription.StringFactory stringFactory = () -> {
+      factoryCalls.incrementAndGet();
+      return "update";
+    };
+
+    UpdateDescription description = UpdateDescription.mentioning(Collections.singletonList(UUID.randomUUID()), stringFactory);
+
+    assertEquals(0, factoryCalls.get());
+
+    setMainThread(false);
+
+    String string = description.getString();
+
+    assertEquals("update", string);
+    assertEquals(1, factoryCalls.get());
+  }
+
+  @Test
+  public void stringFactory_reevaluated_on_every_call() {
+    AtomicInteger                   factoryCalls  = new AtomicInteger();
+    UpdateDescription.StringFactory stringFactory = () -> "call" + factoryCalls.incrementAndGet();
+    UpdateDescription               description   = UpdateDescription.mentioning(Collections.singletonList(UUID.randomUUID()), stringFactory);
+
+    setMainThread(false);
+
+    assertEquals("call1", description.getString());
+    assertEquals("call2", description.getString());
+    assertEquals("call3", description.getString());
+  }
+
+  @Test
+  public void concat_static_lines() {
+    UpdateDescription description1 = UpdateDescription.staticDescription("update1");
+    UpdateDescription description2 = UpdateDescription.staticDescription("update2");
+
+    UpdateDescription description = UpdateDescription.concatWithNewLines(Arrays.asList(description1, description2));
+
+    assertTrue(description.isStringStatic());
+    assertEquals("update1\nupdate2", description.getStaticString());
+    assertEquals("update1\nupdate2", description.getString());
+  }
+
+  @Test
+  public void concat_single_does_not_make_new_object() {
+    UpdateDescription description = UpdateDescription.staticDescription("update1");
+
+    UpdateDescription concat = UpdateDescription.concatWithNewLines(Collections.singletonList(description));
+
+    assertSame(description, concat);
+  }
+
+  @Test
+  public void concat_dynamic_lines() {
+    AtomicInteger                   factoryCalls1  = new AtomicInteger();
+    AtomicInteger                   factoryCalls2  = new AtomicInteger();
+    UpdateDescription.StringFactory stringFactory1 = () -> "update." + factoryCalls1.incrementAndGet();
+    UpdateDescription.StringFactory stringFactory2 = () -> "update." + factoryCalls2.incrementAndGet();
+    UpdateDescription               description1   = UpdateDescription.mentioning(Collections.singletonList(UUID.randomUUID()), stringFactory1);
+    UpdateDescription               description2   = UpdateDescription.mentioning(Collections.singletonList(UUID.randomUUID()), stringFactory2);
+
+    factoryCalls1.set(10);
+    factoryCalls2.set(20);
+
+    UpdateDescription description = UpdateDescription.concatWithNewLines(Arrays.asList(description1, description2));
+
+    assertFalse(description.isStringStatic());
+
+    setMainThread(false);
+
+    assertEquals("update.11\nupdate.21", description.getString());
+    assertEquals("update.12\nupdate.22", description.getString());
+    assertEquals("update.13\nupdate.23", description.getString());
+  }
+
+  @Test
+  public void concat_dynamic_lines_and_static_lines() {
+    AtomicInteger                   factoryCalls1  = new AtomicInteger();
+    AtomicInteger                   factoryCalls2  = new AtomicInteger();
+    UpdateDescription.StringFactory stringFactory1 = () -> "update." + factoryCalls1.incrementAndGet();
+    UpdateDescription.StringFactory stringFactory2 = () -> "update." + factoryCalls2.incrementAndGet();
+    UpdateDescription               description1   = UpdateDescription.mentioning(Collections.singletonList(UUID.randomUUID()), stringFactory1);
+    UpdateDescription               description2   = UpdateDescription.staticDescription("static");
+    UpdateDescription               description3   = UpdateDescription.mentioning(Collections.singletonList(UUID.randomUUID()), stringFactory2);
+
+    factoryCalls1.set(100);
+    factoryCalls2.set(200);
+
+    UpdateDescription description = UpdateDescription.concatWithNewLines(Arrays.asList(description1, description2, description3));
+
+    assertFalse(description.isStringStatic());
+
+    setMainThread(false);
+
+    assertEquals("update.101\nstatic\nupdate.201", description.getString());
+    assertEquals("update.102\nstatic\nupdate.202", description.getString());
+    assertEquals("update.103\nstatic\nupdate.203", description.getString());
+  }
+}

app/src/test/java/org/thoughtcrime/securesms/testutil/MainThreadUtil.java

@@ -0,0 +1,30 @@
+package org.thoughtcrime.securesms.testutil;
+
+import org.thoughtcrime.securesms.util.Util;
+
+import static org.mockito.Mockito.when;
+import static org.powermock.api.mockito.PowerMockito.doCallRealMethod;
+import static org.powermock.api.mockito.PowerMockito.mockStatic;
+
+public final class MainThreadUtil {
+
+  private MainThreadUtil() {
+  }
+
+  /**
+   * Makes {@link Util}'s Main thread assertions pass or fail during tests.
+   * <p>
+   * Use with {@link org.powermock.modules.junit4.PowerMockRunner} or robolectric with powermock
+   * rule and {@code @PrepareForTest(Util.class)}
+   */
+  public static void setMainThread(boolean isMainThread) {
+    mockStatic(Util.class);
+    when(Util.isMainThread()).thenReturn(isMainThread);
+    try {
+      doCallRealMethod().when(Util.class, "assertMainThread");
+      doCallRealMethod().when(Util.class, "assertNotMainThread");
+    } catch (Exception e) {
+      throw new AssertionError();
+    }
+  }
+}

app/src/test/java/org/thoughtcrime/securesms/util/livedata/LiveDataTestUtil.java

@@ -14,7 +14,7 @@ public final class LiveDataTestUtil {
    * <p>
    * This will therefore only work in conjunction with {@link LiveDataRule}.
    */
-  public static <T> T getValue(final LiveData<T> liveData) {
+  public static <T> T observeAndGetOneValue(final LiveData<T> liveData) {
     AtomicReference<T> data     = new AtomicReference<>();
     Observer<T>        observer = data::set;
 

app/src/test/java/org/thoughtcrime/securesms/util/livedata/LiveDataUtilTest_combineLatest.java

@@ -10,9 +10,9 @@ import org.thoughtcrime.securesms.util.DefaultValueLiveData;
 
 import static org.junit.Assert.assertEquals;
 import static org.thoughtcrime.securesms.util.livedata.LiveDataTestUtil.assertNoValue;
-import static org.thoughtcrime.securesms.util.livedata.LiveDataTestUtil.getValue;
+import static org.thoughtcrime.securesms.util.livedata.LiveDataTestUtil.observeAndGetOneValue;
 
-public final class LiveDataUtilTest {
+public final class LiveDataUtilTest_combineLatest {
 
   @Rule
   public TestRule rule = new LiveDataRule();
@@ -61,7 +61,7 @@ public final class LiveDataUtilTest {
     liveDataA.setValue("Hello, ");
     liveDataB.setValue("World!");
 
-    assertEquals("Hello, World!", getValue(combined));
+    assertEquals("Hello, World!", observeAndGetOneValue(combined));
   }
 
   @Test
@@ -74,10 +74,10 @@ public final class LiveDataUtilTest {
     liveDataA.setValue("Hello, ");
     liveDataB.setValue("World!");
 
-    assertEquals("Hello, World!", getValue(combined));
+    assertEquals("Hello, World!", observeAndGetOneValue(combined));
 
     liveDataA.setValue("Welcome, ");
-    assertEquals("Welcome, World!", getValue(combined));
+    assertEquals("Welcome, World!", observeAndGetOneValue(combined));
   }
 
   @Test
@@ -90,10 +90,10 @@ public final class LiveDataUtilTest {
     liveDataA.setValue("Hello, ");
     liveDataB.setValue("World!");
 
-    assertEquals("Hello, World!", getValue(combined));
+    assertEquals("Hello, World!", observeAndGetOneValue(combined));
 
     liveDataB.setValue("Joe!");
-    assertEquals("Hello, Joe!", getValue(combined));
+    assertEquals("Hello, Joe!", observeAndGetOneValue(combined));
   }
 
   @Test
@@ -104,7 +104,7 @@ public final class LiveDataUtilTest {
 
     liveDataA.setValue("Echo! ");
 
-    assertEquals("Echo! Echo! ", getValue(combined));
+    assertEquals("Echo! Echo! ", observeAndGetOneValue(combined));
   }
 
   @Test
@@ -118,7 +118,7 @@ public final class LiveDataUtilTest {
 
     liveDataB.setValue("World!");
 
-    assertEquals("Hello, World!", getValue(combined));
+    assertEquals("Hello, World!", observeAndGetOneValue(combined));
   }
 
   @Test
@@ -128,6 +128,6 @@ public final class LiveDataUtilTest {
 
     LiveData<Integer> combined = LiveDataUtil.combineLatest(liveDataA, liveDataB, (a, b) -> a * b);
 
-    assertEquals(Integer.valueOf(300), getValue(combined));
+    assertEquals(Integer.valueOf(300), observeAndGetOneValue(combined));
   }
 }

app/src/test/java/org/thoughtcrime/securesms/util/livedata/LiveDataUtilTest_merge.java

@@ -0,0 +1,161 @@
+package org.thoughtcrime.securesms.util.livedata;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TestRule;
+import org.thoughtcrime.securesms.util.DefaultValueLiveData;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
+import static org.thoughtcrime.securesms.util.livedata.LiveDataTestUtil.assertNoValue;
+import static org.thoughtcrime.securesms.util.livedata.LiveDataTestUtil.observeAndGetOneValue;
+
+public final class LiveDataUtilTest_merge {
+
+  @Rule
+  public TestRule rule = new LiveDataRule();
+
+  @Test
+  public void merge_nothing() {
+    LiveData<String> combined = LiveDataUtil.merge(Collections.emptyList());
+
+    assertNoValue(combined);
+  }
+  
+  @Test
+  public void merge_one_is_a_no_op() {
+    MutableLiveData<String> liveDataA = new MutableLiveData<>();
+    
+    LiveData<String> combined = LiveDataUtil.merge(Collections.singletonList(liveDataA));
+
+    assertSame(liveDataA, combined);
+  }
+
+  @Test
+  public void initially_no_value() {
+    MutableLiveData<String> liveDataA = new MutableLiveData<>();
+    MutableLiveData<String> liveDataB = new MutableLiveData<>();
+
+    LiveData<String> combined = LiveDataUtil.merge(Arrays.asList(liveDataA, liveDataB));
+
+    assertNoValue(combined);
+  }
+
+  @Test
+  public void value_on_first() {
+    MutableLiveData<String> liveDataA = new MutableLiveData<>();
+    MutableLiveData<String> liveDataB = new MutableLiveData<>();
+
+    LiveData<String> combined = LiveDataUtil.merge(Arrays.asList(liveDataA, liveDataB));
+
+    liveDataA.setValue("A");
+
+    assertEquals("A", observeAndGetOneValue(combined));
+  }
+
+  @Test
+  public void value_on_second() {
+    MutableLiveData<String> liveDataA = new MutableLiveData<>();
+    MutableLiveData<String> liveDataB = new MutableLiveData<>();
+
+    LiveData<String> combined = LiveDataUtil.merge(Arrays.asList(liveDataA, liveDataB));
+
+    liveDataB.setValue("B");
+
+    assertEquals("B", observeAndGetOneValue(combined));
+  }
+
+  @Test
+  public void value_on_third() {
+    MutableLiveData<String> liveDataA = new MutableLiveData<>();
+    MutableLiveData<String> liveDataB = new MutableLiveData<>();
+    MutableLiveData<String> liveDataC = new MutableLiveData<>();
+
+    LiveData<String> combined = LiveDataUtil.merge(Arrays.asList(liveDataA, liveDataB, liveDataC));
+
+    liveDataC.setValue("C");
+
+    assertEquals("C", observeAndGetOneValue(combined));
+  }
+
+  @Test
+  public void several_values_merged() {
+    MutableLiveData<String> liveDataA = new MutableLiveData<>();
+    MutableLiveData<String> liveDataB = new MutableLiveData<>();
+    MutableLiveData<String> liveDataC = new MutableLiveData<>();
+
+    LiveData<String> combined = LiveDataUtil.merge(Arrays.asList(liveDataA, liveDataB, liveDataC));
+
+    liveDataC.setValue("C");
+
+    assertEquals("C", observeAndGetOneValue(combined));
+
+    liveDataA.setValue("A");
+
+    assertEquals("A", observeAndGetOneValue(combined));
+
+    liveDataB.setValue("B");
+
+    assertEquals("B", observeAndGetOneValue(combined));
+  }
+
+  @Test
+  public void combined_same_instance() {
+    MutableLiveData<String> liveDataA = new MutableLiveData<>();
+
+    LiveData<String> combined = LiveDataUtil.merge(Arrays.asList(liveDataA, liveDataA));
+
+    liveDataA.setValue("Echo! ");
+
+    assertSame(liveDataA, combined);
+  }
+
+  @Test
+  public void combined_same_instances_repeated() {
+    MutableLiveData<String> liveDataA = new MutableLiveData<>();
+    MutableLiveData<String> liveDataB = new MutableLiveData<>();
+    MutableLiveData<String> liveDataC = new MutableLiveData<>();
+
+    LiveData<String> combined = LiveDataUtil.merge(Arrays.asList(liveDataA, liveDataB, liveDataC, liveDataA, liveDataB, liveDataC));
+
+    liveDataC.setValue("C");
+
+    assertEquals("C", observeAndGetOneValue(combined));
+
+    liveDataA.setValue("A");
+
+    assertEquals("A", observeAndGetOneValue(combined));
+
+    liveDataB.setValue("B");
+
+    assertEquals("B", observeAndGetOneValue(combined));
+  }
+
+  @Test
+  public void on_a_set_before_combine() {
+    MutableLiveData<String> liveDataA = new MutableLiveData<>();
+    MutableLiveData<String> liveDataB = new MutableLiveData<>();
+
+    liveDataA.setValue("A");
+
+    LiveData<String> combined = LiveDataUtil.merge(Arrays.asList(liveDataA, liveDataB));
+
+    assertEquals("A", observeAndGetOneValue(combined));
+  }
+
+  @Test
+  public void on_default_values() {
+    MutableLiveData<Integer> liveDataA = new DefaultValueLiveData<>(10);
+    MutableLiveData<Integer> liveDataB = new DefaultValueLiveData<>(30);
+
+    LiveData<Integer> combined = LiveDataUtil.merge(Arrays.asList(liveDataA, liveDataB));
+
+    assertEquals(Integer.valueOf(30), observeAndGetOneValue(combined));
+  }
+}

libsignal/service/src/main/java/org/whispersystems/signalservice/api/util/UuidUtil.java

@@ -63,6 +63,11 @@ public final class UuidUtil {
     return parseOrNull(bytes.toByteArray());
   }
 
+  public static UUID fromByteStringOrUnknown(ByteString bytes) {
+    UUID uuid = fromByteStringOrNull(bytes);
+    return uuid != null ? uuid : UNKNOWN_UUID;
+  }
+
   private static UUID parseOrNull(byte[] byteArray) {
     return byteArray != null && byteArray.length == 16 ? parseOrThrow(byteArray) : null;
   }