Better explain why messages could not be deleted

This also fixes a bug in the IntroductionManager that would allow to
delete only part of a session's visible messages.

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -67,6 +67,7 @@ import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
 import org.briarproject.briar.api.conversation.ConversationRequest;
 import org.briarproject.briar.api.conversation.ConversationResponse;
+import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
 import org.briarproject.briar.api.forum.ForumSharingManager;
 import org.briarproject.briar.api.introduction.IntroductionManager;
@@ -857,9 +858,9 @@ public class ConversationActivity extends BriarActivity
 		list.showProgressBar();
 		runOnDbThread(() -> {
 			try {
-				boolean allDeleted =
+				DeletionResult result =
 						conversationManager.deleteAllMessages(contactId);
-				reloadConversationAfterDeletingMessages(allDeleted);
+				reloadConversationAfterDeletingMessages(result);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				runOnUiThreadUnlessDestroyed(() -> list.showData());
@@ -874,9 +875,9 @@ public class ConversationActivity extends BriarActivity
 		if (actionMode != null) actionMode.finish();
 		runOnDbThread(() -> {
 			try {
-				boolean allDeleted =
+				DeletionResult result =
 						conversationManager.deleteMessages(contactId, selected);
-				reloadConversationAfterDeletingMessages(allDeleted);
+				reloadConversationAfterDeletingMessages(result);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				runOnUiThreadUnlessDestroyed(() -> list.showData());
@@ -885,22 +886,55 @@ public class ConversationActivity extends BriarActivity
 	}
 
 	private void reloadConversationAfterDeletingMessages(
-			boolean allDeleted) {
+			DeletionResult result) {
 		runOnUiThreadUnlessDestroyed(() -> {
 			adapter.clear();
 			list.showProgressBar();  // otherwise clearing shows empty state
 			loadMessages();
-			if (!allDeleted) showNotAllDeletedDialog();
+			if (!result.allDeleted()) showNotAllDeletedDialog(result);
 		});
 	}
 
-	private void showNotAllDeletedDialog() {
+	private void showNotAllDeletedDialog(DeletionResult result) {
+		StringBuilder msg = new StringBuilder();
+		// get failures the user can not immediately prevent
+		StringBuilder fails = new StringBuilder();
+		if (result.hasSessionInProgress()) {
+			if (result.hasIntroduction()) {
+				String s = getString(
+						R.string.dialog_message_not_deleted_ongoing_introductions);
+				fails.append(s).append("\n");
+			}
+			if (result.hasInvitation()) {
+				String s = getString(
+						R.string.dialog_message_not_deleted_ongoing_invitations);
+				fails.append(s).append("\n");
+			}
+		}
+		if (result.hasNotFullyDownloaded()) {
+			String s = getString(
+					R.string.dialog_message_not_deleted_partly_downloaded);
+			fails.append(s).append("\n");
+		}
+		// add failures to message if there are any
+		if (fails.length() > 0) {
+			String s = getString(R.string.dialog_message_not_deleted,
+					fails.toString());
+			msg.append(s);
+		}
+		// add problems the user can resolve
+		if (result.hasNotAllSelected()) {
+			if (msg.length() > 0) msg.append("\n\n");
+			String s = getString(
+					R.string.dialog_message_not_deleted_not_all_selected);
+			msg.append(s);
+		}
+		// show dialog
 		AlertDialog.Builder builder =
 				new AlertDialog.Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(
 				getString(R.string.dialog_title_not_all_messages_deleted));
-		builder.setMessage(
-				getString(R.string.dialog_message_not_all_messages_deleted));
+		builder.setMessage(msg.toString());
 		builder.setPositiveButton(R.string.ok, null);
 		builder.show();
 	}
@@ -912,7 +946,8 @@ public class ConversationActivity extends BriarActivity
 				new AlertDialog.Builder(ConversationActivity.this,
 						R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.dialog_title_delete_contact));
-		builder.setMessage(getString(R.string.dialog_message_delete_contact));
+		builder.setMessage(
+				getString(R.string.dialog_message_delete_contact));
 		builder.setNegativeButton(R.string.delete, okListener);
 		builder.setPositiveButton(R.string.cancel, null);
 		builder.show();
@@ -953,7 +988,8 @@ public class ConversationActivity extends BriarActivity
 
 	private void showImageOnboarding() {
 		// TODO: remove cast when removing feature flag
-		((TextAttachmentController) sendController).showImageOnboarding(this);
+		((TextAttachmentController) sendController)
+				.showImageOnboarding(this);
 	}
 
 	private void showIntroductionOnboarding(@Nullable Boolean show) {
@@ -973,7 +1009,8 @@ public class ConversationActivity extends BriarActivity
 		View target = null;
 		for (int i = 0; i < toolbar.getChildCount(); i++) {
 			if (toolbar.getChildAt(i) instanceof ActionMenuView) {
-				ActionMenuView menu = (ActionMenuView) toolbar.getChildAt(i);
+				ActionMenuView menu =
+						(ActionMenuView) toolbar.getChildAt(i);
 				// The overflow icon should be the last child of the menu
 				target = menu.getChildAt(menu.getChildCount() - 1);
 				// If the menu hasn't been populated yet, use the menu itself
@@ -999,7 +1036,8 @@ public class ConversationActivity extends BriarActivity
 
 	@UiThread
 	@Override
-	public void respondToRequest(ConversationRequestItem item, boolean accept) {
+	public void respondToRequest(ConversationRequestItem item,
+			boolean accept) {
 		item.setAnswered();
 		int position = adapter.findItemPosition(item);
 		if (position != INVALID_POSITION) {

briar-android/src/main/res/values/strings.xml

@@ -139,7 +139,11 @@
 	<string name="dialog_title_delete_all_messages">Confirm Message Deletion</string>
 	<string name="dialog_message_delete_all_messages">Are you sure that you want to delete all messages?</string>
 	<string name="dialog_title_not_all_messages_deleted">Could not delete all messages</string>
-	<string name="dialog_message_not_all_messages_deleted">Messages related to\n\n• ongoing introductions\n• ongoing (blog/forum/group) invitations\n• partly downloaded messages\n\ncannot be deleted until they conclude.</string>
+	<string name="dialog_message_not_deleted">Messages related to\n\n%s\ncan not be deleted until they conclude.</string>
+	<string name="dialog_message_not_deleted_ongoing_introductions">• ongoing introductions</string>
+	<string name="dialog_message_not_deleted_ongoing_invitations">• ongoing (blog/forum/group) invitations</string>
+	<string name="dialog_message_not_deleted_partly_downloaded">• partly downloaded messages</string>
+	<string name="dialog_message_not_deleted_not_all_selected">To delete an invitation/introduction, you need to select the request and the response.</string>
 	<string name="delete_contact">Delete contact</string>
 	<string name="dialog_title_delete_contact">Confirm Contact Deletion</string>
 	<string name="dialog_message_delete_contact">Are you sure that you want to remove this contact and all messages exchanged with this contact?</string>

briar-api/src/main/java/org/briarproject/briar/api/conversation/ConversationManager.java

@@ -17,6 +17,12 @@ import java.util.Set;
 @NotNullByDefault
 public interface ConversationManager {
 
+	int DELETE_SESSION_IS_INTRODUCTION = 1;
+	int DELETE_SESSION_IS_INVITATION = 1 << 1;
+	int DELETE_SESSION_INCOMPLETE = 1 << 2;
+	int DELETE_SESSION_IN_PROGRESS = 1 << 3;
+	int DELETE_NOT_DOWNLOADED = 1 << 4;
+
 	/**
 	 * Clients that present messages in a private conversation need to
 	 * register themselves here.
@@ -39,17 +45,13 @@ public interface ConversationManager {
 
 	/**
 	 * Deletes all messages exchanged with the given contact.
-	 *
-	 * @return true if all messages could be deleted, false otherwise
 	 */
-	boolean deleteAllMessages(ContactId c) throws DbException;
+	DeletionResult deleteAllMessages(ContactId c) throws DbException;
 
 	/**
 	 * Deletes the given set of messages associated with the given contact.
-	 *
-	 * @return true if all given messages could be deleted, false otherwise
 	 */
-	boolean deleteMessages(ContactId c, Collection<MessageId> messageIds)
+	DeletionResult deleteMessages(ContactId c, Collection<MessageId> messageIds)
 			throws DbException;
 
 	@NotNullByDefault
@@ -75,10 +77,8 @@ public interface ConversationManager {
 
 		/**
 		 * Deletes all messages associated with the given contact.
-		 *
-		 * @return true if all messages could be deleted, false otherwise
 		 */
-		boolean deleteAllMessages(Transaction txn,
+		DeletionResult deleteAllMessages(Transaction txn,
 				ContactId c) throws DbException;
 
 		/**
@@ -86,10 +86,8 @@ public interface ConversationManager {
 		 * <p>
 		 * The set of message IDs must only include message IDs returned by
 		 * {@link #getMessageIds}.
-		 *
-		 * @return true if all messages could be deleted, false otherwise
 		 */
-		boolean deleteMessages(Transaction txn, ContactId c,
+		DeletionResult deleteMessages(Transaction txn, ContactId c,
 				Set<MessageId> messageIds) throws DbException;
 	}
 

briar-api/src/main/java/org/briarproject/briar/api/conversation/DeletionResult.java

@@ -0,0 +1,67 @@
+package org.briarproject.briar.api.conversation;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.NotThreadSafe;
+
+import static org.briarproject.briar.api.conversation.ConversationManager.DELETE_NOT_DOWNLOADED;
+import static org.briarproject.briar.api.conversation.ConversationManager.DELETE_SESSION_INCOMPLETE;
+import static org.briarproject.briar.api.conversation.ConversationManager.DELETE_SESSION_IN_PROGRESS;
+import static org.briarproject.briar.api.conversation.ConversationManager.DELETE_SESSION_IS_INTRODUCTION;
+import static org.briarproject.briar.api.conversation.ConversationManager.DELETE_SESSION_IS_INVITATION;
+
+@NotThreadSafe
+@NotNullByDefault
+public class DeletionResult {
+
+	private int result = 0;
+
+	public void addDeletionResult(DeletionResult deletionResult) {
+		result |= deletionResult.result;
+	}
+
+	public void addInvitationNotAllSelected() {
+		result |= DELETE_SESSION_INCOMPLETE | DELETE_SESSION_IS_INVITATION;
+	}
+
+	public void addInvitationSessionInProgress() {
+		result |= DELETE_SESSION_IN_PROGRESS | DELETE_SESSION_IS_INVITATION;
+	}
+
+	public void addIntroductionNotAllSelected() {
+		result |= DELETE_SESSION_INCOMPLETE | DELETE_SESSION_IS_INTRODUCTION;
+	}
+
+	public void addIntroductionSessionInProgress() {
+		result |= DELETE_SESSION_IN_PROGRESS | DELETE_SESSION_IS_INTRODUCTION;
+	}
+
+	public void addNotFullyDownloaded() {
+		result |= DELETE_NOT_DOWNLOADED;
+	}
+
+	public boolean allDeleted() {
+		return result == 0;
+	}
+
+	public boolean hasIntroduction() {
+		return (result & DELETE_SESSION_IS_INTRODUCTION) != 0;
+	}
+
+	public boolean hasInvitation() {
+		return (result & DELETE_SESSION_IS_INVITATION) != 0;
+	}
+
+	public boolean hasSessionInProgress() {
+		return (result & DELETE_SESSION_IN_PROGRESS) != 0;
+	}
+
+	public boolean hasNotAllSelected() {
+		return (result & DELETE_SESSION_INCOMPLETE) != 0;
+	}
+
+	public boolean hasNotFullyDownloaded() {
+		return (result & DELETE_NOT_DOWNLOADED) != 0;
+	}
+
+}

briar-core/src/main/java/org/briarproject/briar/introduction/IntroductionManagerImpl.java

@@ -32,6 +32,7 @@ import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVer
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.introduction.IntroductionManager;
 import org.briarproject.briar.api.introduction.IntroductionRequest;
 import org.briarproject.briar.api.introduction.IntroductionResponse;
@@ -561,73 +562,45 @@ class IntroductionManagerImpl extends ConversationClientImpl
 
 	@FunctionalInterface
 	private interface MessageRetriever {
-		Map<MessageId, BdfDictionary> getMessages(Transaction txn,
-				GroupId contactGroup) throws DbException;
-	}
-
-	@FunctionalInterface
-	private interface MessageDeletionChecker {
-		/**
-		 * This is called for all messages belonging to a session.
-		 * It returns true if the given {@link MessageId} causes a problem
-		 * so that the session can not be deleted.
-		 */
-		boolean causesProblem(MessageId messageId);
+		Set<MessageId> getMessages(Set<MessageId> allMessages);
 	}
 
 	@Override
-	public boolean deleteAllMessages(Transaction txn, ContactId c)
+	public DeletionResult deleteAllMessages(Transaction txn, ContactId c)
 			throws DbException {
-		return deleteMessages(txn, c, (txn1, g) -> {
-			// get metadata for all messages in the group
-			Map<MessageId, BdfDictionary> messages;
-			try {
-				messages = clientHelper.getMessageMetadataAsDictionary(txn1, g);
-			} catch (FormatException e) {
-				throw new DbException(e);
-			}
-			return messages;
-		}, messageId -> false);
+		return deleteMessages(txn, c, allMessages -> allMessages);
 	}
 
 	@Override
-	public boolean deleteMessages(Transaction txn, ContactId c,
+	public DeletionResult deleteMessages(Transaction txn, ContactId c,
 			Set<MessageId> messageIds) throws DbException {
-		return deleteMessages(txn, c, (txn1, g) -> {
-			// get metadata for messages that shall be deleted
-			Map<MessageId, BdfDictionary> messages =
-					new HashMap<>(messageIds.size());
-			for (MessageId m : messageIds) {
-				BdfDictionary d;
-				try {
-					d = clientHelper.getMessageMetadataAsDictionary(txn1, m);
-				} catch (FormatException e) {
-					throw new DbException(e);
-				}
-				// If message metadata does not exist,
-				// getMessageMetadataAsDictionary(txn, m) returns empty Metadata
-				if (!d.isEmpty()) messages.put(m, d);
-			}
-			return messages;
-			// don't delete sessions if a message is not part of messageIds
-		}, messageId -> !messageIds.contains(messageId));
+		return deleteMessages(txn, c, allMessages -> messageIds);
 	}
 
-	private boolean deleteMessages(Transaction txn, ContactId c,
-			MessageRetriever retriever, MessageDeletionChecker checker)
-			throws DbException {
+	private DeletionResult deleteMessages(Transaction txn, ContactId c,
+			MessageRetriever retriever) throws DbException {
 		// get ID of the contact group
 		GroupId g = getContactGroup(db.getContact(txn, c)).getId();
 
-		// get messages to be deleted
-		Map<MessageId, BdfDictionary> messages = retriever.getMessages(txn, g);
+		// get metadata for all messages in the group
+		Map<MessageId, BdfDictionary> messages;
+		try {
+			messages = clientHelper.getMessageMetadataAsDictionary(txn, g);
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
 
-		// assign protocol messages to their sessions
+		// get messages to be deleted
+		Set<MessageId> selected = retriever.getMessages(messages.keySet());
+
+		// get sessions for selected messages
 		Map<SessionId, DeletableSession> sessions = new HashMap<>();
-		for (Entry<MessageId, BdfDictionary> entry : messages.entrySet()) {
+		for (MessageId id : selected) {
+			BdfDictionary d = messages.get(id);
+			if (d == null) continue;  // throw new NoSuchMessageException()
 			MessageMetadata m;
 			try {
-				m = messageParser.parseMetadata(entry.getValue());
+				m = messageParser.parseMetadata(d);
 			} catch (FormatException e) {
 				throw new DbException(e);
 			}
@@ -644,6 +617,31 @@ class IntroductionManagerImpl extends ConversationClientImpl
 				session = getDeletableSession(txn, g, m.getSessionId());
 				sessions.put(m.getSessionId(), session);
 			}
+			session.messages.add(id);
+		}
+
+		// assign other protocol messages to their sessions
+		for (Entry<MessageId, BdfDictionary> entry : messages.entrySet()) {
+			// we handled selected messages above
+			if (selected.contains(entry.getKey())) continue;
+
+			MessageMetadata m;
+			try {
+				m = messageParser.parseMetadata(entry.getValue());
+			} catch (FormatException e) {
+				throw new DbException(e);
+			}
+			if (!m.isVisibleInConversation()) continue;
+			if (m.getSessionId() == null) {
+				// This can only be an unhandled REQUEST message.
+				// Its session is created and stored in incomingMessage(),
+				// and getMessageMetadata() only returns delivered messages,
+				// so the session ID should have been assigned.
+				throw new AssertionError("missing session ID");
+			}
+			// get session from map or database
+			DeletableSession session = sessions.get(m.getSessionId());
+			if (session == null) continue;  // not a session of a selected msg
 			session.messages.add(entry.getKey());
 		}
 
@@ -652,10 +650,10 @@ class IntroductionManagerImpl extends ConversationClientImpl
 		for (MessageStatus status : db.getMessageStatus(txn, c, g)) {
 			if (!status.isSeen()) notAcked.add(status.getMessageId());
 		}
-		boolean allDeleted =
-				deleteCompletedSessions(txn, sessions, notAcked, checker);
+		DeletionResult result =
+				deleteCompletedSessions(txn, sessions, notAcked, selected);
 		recalculateGroupCount(txn, g);
-		return allDeleted;
+		return result;
 	}
 
 	private DeletableSession getDeletableSession(Transaction txn,
@@ -677,28 +675,31 @@ class IntroductionManagerImpl extends ConversationClientImpl
 		}
 	}
 
-	private boolean deleteCompletedSessions(Transaction txn,
+	private DeletionResult deleteCompletedSessions(Transaction txn,
 			Map<SessionId, DeletableSession> sessions, Set<MessageId> notAcked,
-			MessageDeletionChecker checker) throws DbException {
+			Set<MessageId> selected) throws DbException {
 		// find completed sessions to delete
-		boolean allDeleted = true;
+		DeletionResult result = new DeletionResult();
 		for (DeletableSession session : sessions.values()) {
 			if (!session.state.isComplete()) {
-				allDeleted = false;
+				result.addIntroductionSessionInProgress();
 				continue;
 			}
 			// we can only delete sessions
 			// where delivery of all messages was confirmed (aka ACKed)
-			boolean allAcked = true;
+			boolean sessionDeletable = true;
 			for (MessageId m : session.messages) {
-				if (notAcked.contains(m) || checker.causesProblem(m)) {
-					allAcked = false;
-					allDeleted = false;
+				if (notAcked.contains(m) || !selected.contains(m)) {
+					sessionDeletable = false;
+					if (notAcked.contains(m))
+						result.addIntroductionSessionInProgress();
+					if (!selected.contains(m))
+						result.addIntroductionNotAllSelected();
 					break;
 				}
 			}
 			// delete messages of session, if all were ACKed
-			if (allAcked) {
+			if (sessionDeletable) {
 				for (MessageId m : session.messages) {
 					db.deleteMessage(txn, m);
 					db.deleteMessageMetadata(txn, m);
@@ -707,7 +708,7 @@ class IntroductionManagerImpl extends ConversationClientImpl
 				// and then needs the previous MessageIds
 			}
 		}
-		return allDeleted;
+		return result;
 	}
 
 	@Override

briar-core/src/main/java/org/briarproject/briar/messaging/ConversationManagerImpl.java

@@ -9,6 +9,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.conversation.DeletionResult;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -75,27 +76,27 @@ class ConversationManagerImpl implements ConversationManager {
 	}
 
 	@Override
-	public boolean deleteAllMessages(ContactId c) throws DbException {
+	public DeletionResult deleteAllMessages(ContactId c) throws DbException {
 		return db.transactionWithResult(false, txn -> {
-			boolean allDeleted = true;
+			DeletionResult result = new DeletionResult();
 			for (ConversationClient client : clients) {
-				allDeleted = client.deleteAllMessages(txn, c) && allDeleted;
+				result.addDeletionResult(client.deleteAllMessages(txn, c));
 			}
-			return allDeleted;
+			return result;
 		});
 	}
 
 	@Override
-	public boolean deleteMessages(ContactId c, Collection<MessageId> toDelete)
+	public DeletionResult deleteMessages(ContactId c, Collection<MessageId> toDelete)
 			throws DbException {
 		return db.transactionWithResult(false, txn -> {
-			boolean allDeleted = true;
+			DeletionResult result = new DeletionResult();
 			for (ConversationClient client : clients) {
 				Set<MessageId> idSet = client.getMessageIds(txn, c);
 				idSet.retainAll(toDelete);
-				allDeleted = client.deleteMessages(txn, c, idSet) && allDeleted;
+				result.addDeletionResult(client.deleteMessages(txn, c, idSet));
 			}
-			return allDeleted;
+			return result;
 		});
 	}
 

briar-core/src/main/java/org/briarproject/briar/messaging/MessagingManagerImpl.java

@@ -31,6 +31,7 @@ import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 import org.briarproject.briar.api.conversation.ConversationManager.ConversationClient;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.FileTooBigException;
@@ -430,7 +431,7 @@ class MessagingManagerImpl implements MessagingManager, IncomingMessageHook,
 	}
 
 	@Override
-	public boolean deleteAllMessages(Transaction txn, ContactId c)
+	public DeletionResult deleteAllMessages(Transaction txn, ContactId c)
 			throws DbException {
 		GroupId g = getContactGroup(db.getContact(txn, c)).getId();
 		// this indiscriminately deletes all raw messages in this group
@@ -440,13 +441,13 @@ class MessagingManagerImpl implements MessagingManager, IncomingMessageHook,
 			db.deleteMessageMetadata(txn, messageId);
 		}
 		messageTracker.initializeGroupCount(txn, g);
-		return true;
+		return new DeletionResult();
 	}
 
 	@Override
-	public boolean deleteMessages(Transaction txn, ContactId c,
+	public DeletionResult deleteMessages(Transaction txn, ContactId c,
 			Set<MessageId> messageIds) throws DbException {
-		boolean allDeleted = true;
+		DeletionResult result = new DeletionResult();
 		for (MessageId m : messageIds) {
 			// get attachment headers
 			List<AttachmentHeader> headers;
@@ -480,12 +481,12 @@ class MessagingManagerImpl implements MessagingManager, IncomingMessageHook,
 				db.deleteMessage(txn, m);
 				db.deleteMessageMetadata(txn, m);
 			} else {
-				allDeleted = false;
+				result.addNotFullyDownloaded();
 			}
 		}
 		GroupId g = getContactGroup(db.getContact(txn, c)).getId();
 		recalculateGroupCount(txn, g);
-		return allDeleted;
+		return result;
 	}
 
 	private void recalculateGroupCount(Transaction txn, GroupId g)

briar-core/src/main/java/org/briarproject/briar/privategroup/invitation/GroupInvitationManagerImpl.java

@@ -27,6 +27,7 @@ import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVer
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
 import org.briarproject.briar.api.privategroup.PrivateGroupFactory;
 import org.briarproject.briar.api.privategroup.PrivateGroupManager;
@@ -636,7 +637,7 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 	}
 
 	@Override
-	public boolean deleteAllMessages(Transaction txn, ContactId c)
+	public DeletionResult deleteAllMessages(Transaction txn, ContactId c)
 			throws DbException {
 		return deleteMessages(txn, c, (txn1, g, metadata) -> {
 			// get all sessions and their states
@@ -657,7 +658,7 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 	}
 
 	@Override
-	public boolean deleteMessages(Transaction txn, ContactId c,
+	public DeletionResult deleteMessages(Transaction txn, ContactId c,
 			Set<MessageId> messageIds) throws DbException {
 		return deleteMessages(txn, c, (txn1, g, metadata) -> {
 			// get only sessions from given messageIds
@@ -685,7 +686,7 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 		}, messageId -> !messageIds.contains(messageId));
 	}
 
-	private boolean deleteMessages(Transaction txn, ContactId c,
+	private DeletionResult deleteMessages(Transaction txn, ContactId c,
 			DeletableSessionRetriever retriever, MessageDeletionChecker checker)
 			throws DbException {
 		// get ID of the contact group
@@ -729,40 +730,43 @@ class GroupInvitationManagerImpl extends ConversationClientImpl
 		for (MessageStatus status : db.getMessageStatus(txn, c, g)) {
 			if (!status.isSeen()) notAcked.add(status.getMessageId());
 		}
-		boolean allDeleted = deleteCompletedSessions(txn, sessions.values(),
+		DeletionResult result = deleteCompletedSessions(txn, sessions.values(),
 				notAcked, checker);
 		recalculateGroupCount(txn, g);
-		return allDeleted;
+		return result;
 	}
 
-	private boolean deleteCompletedSessions(Transaction txn,
+	private DeletionResult deleteCompletedSessions(Transaction txn,
 			Collection<DeletableSession> sessions, Set<MessageId> notAcked,
 			MessageDeletionChecker checker) throws DbException {
 		// find completed sessions to delete
-		boolean allDeleted = true;
+		DeletionResult result = new DeletionResult();
 		for (DeletableSession session : sessions) {
 			if (session.state.isAwaitingResponse()) {
-				allDeleted = false;
+				result.addInvitationSessionInProgress();
 				continue;
 			}
 			// we can only delete sessions
 			// where delivery of all messages was confirmed (aka ACKed)
-			boolean allAcked = true;
+			boolean sessionDeletable = true;
 			for (MessageId m : session.messages) {
 				if (notAcked.contains(m) || checker.causesProblem(m)) {
-					allAcked = false;
-					allDeleted = false;
+					sessionDeletable = false;
+					if (notAcked.contains(m))
+						result.addInvitationSessionInProgress();
+					if (checker.causesProblem(m))
+						result.addInvitationNotAllSelected();
 					break;
 				}
 			}
-			if (allAcked) {
+			if (sessionDeletable) {
 				for (MessageId m : session.messages) {
 					db.deleteMessage(txn, m);
 					db.deleteMessageMetadata(txn, m);
 				}
 			}
 		}
-		return allDeleted;
+		return result;
 	}
 
 	@Override

briar-core/src/main/java/org/briarproject/briar/sharing/SharingManagerImpl.java

@@ -28,6 +28,7 @@ import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
 import org.briarproject.briar.api.conversation.ConversationRequest;
+import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.sharing.InvitationResponse;
 import org.briarproject.briar.api.sharing.Shareable;
 import org.briarproject.briar.api.sharing.SharingInvitationItem;
@@ -557,7 +558,7 @@ abstract class SharingManagerImpl<S extends Shareable>
 	}
 
 	@Override
-	public boolean deleteAllMessages(Transaction txn, ContactId c)
+	public DeletionResult deleteAllMessages(Transaction txn, ContactId c)
 			throws DbException {
 		return deleteMessages(txn, c, (txn1, contactGroup, metadata) -> {
 			// get all sessions and their states
@@ -578,7 +579,7 @@ abstract class SharingManagerImpl<S extends Shareable>
 	}
 
 	@Override
-	public boolean deleteMessages(Transaction txn, ContactId c,
+	public DeletionResult deleteMessages(Transaction txn, ContactId c,
 			Set<MessageId> messageIds) throws DbException {
 		return deleteMessages(txn, c, (txn1, g, metadata) -> {
 			// get only sessions from given messageIds
@@ -606,7 +607,7 @@ abstract class SharingManagerImpl<S extends Shareable>
 		}, messageId -> !messageIds.contains(messageId));
 	}
 
-	private boolean deleteMessages(Transaction txn, ContactId c,
+	private DeletionResult deleteMessages(Transaction txn, ContactId c,
 			DeletableSessionRetriever retriever, MessageDeletionChecker checker)
 			throws DbException {
 		// get ID of the contact group
@@ -621,7 +622,7 @@ abstract class SharingManagerImpl<S extends Shareable>
 			throw new DbException(e);
 		}
 
-		// get all sessions and their states
+		// get sessions and their states
 		Map<GroupId, DeletableSession> sessions =
 				retriever.getDeletableSessions(txn, g, metadata);
 
@@ -650,40 +651,43 @@ abstract class SharingManagerImpl<S extends Shareable>
 		for (MessageStatus status : db.getMessageStatus(txn, c, g)) {
 			if (!status.isSeen()) notAcked.add(status.getMessageId());
 		}
-		boolean allDeleted = deleteCompletedSessions(txn, sessions.values(),
+		DeletionResult result = deleteCompletedSessions(txn, sessions.values(),
 				notAcked, checker);
 		recalculateGroupCount(txn, g);
-		return allDeleted;
+		return result;
 	}
 
-	private boolean deleteCompletedSessions(Transaction txn,
+	private DeletionResult deleteCompletedSessions(Transaction txn,
 			Collection<DeletableSession> sessions, Set<MessageId> notAcked,
 			MessageDeletionChecker checker) throws DbException {
 		// find completed sessions to delete
-		boolean allDeleted = true;
+		DeletionResult result = new DeletionResult();
 		for (DeletableSession session : sessions) {
 			if (session.state.isAwaitingResponse()) {
-				allDeleted = false;
+				result.addInvitationSessionInProgress();
 				continue;
 			}
 			// we can only delete sessions
 			// where delivery of all messages was confirmed (aka ACKed)
-			boolean allAcked = true;
+			boolean sessionDeletable = true;
 			for (MessageId m : session.messages) {
 				if (notAcked.contains(m) || checker.causesProblem(m)) {
-					allAcked = false;
-					allDeleted = false;
+					sessionDeletable = false;
+					if (notAcked.contains(m))
+						result.addInvitationSessionInProgress();
+					if (checker.causesProblem(m))
+						result.addInvitationNotAllSelected();
 					break;
 				}
 			}
-			if (allAcked) {
+			if (sessionDeletable) {
 				for (MessageId m : session.messages) {
 					db.deleteMessage(txn, m);
 					db.deleteMessageMetadata(txn, m);
 				}
 			}
 		}
-		return allDeleted;
+		return result;
 	}
 
 	@Override

briar-core/src/test/java/org/briarproject/briar/introduction/IntroductionIntegrationTest.java

@@ -28,6 +28,7 @@ import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
 import org.briarproject.briar.api.conversation.ConversationResponse;
+import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.introduction.IntroductionManager;
 import org.briarproject.briar.api.introduction.IntroductionRequest;
 import org.briarproject.briar.api.introduction.IntroductionResponse;
@@ -1152,61 +1153,77 @@ public class IntroductionIntegrationTest
 		eventWaiter.await(TIMEOUT, 1);
 
 		// introducer can not yet remove messages
-		assertFalse(deleteAllMessages1From0());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages1From0().hasIntroduction());
+		assertTrue(deleteAllMessages1From0().hasSessionInProgress());
 		// introducee1 can not yet remove messages
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasIntroduction());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 
 		// sync second REQUEST message
 		sync0To2(1, true);
 		eventWaiter.await(TIMEOUT, 1);
 
 		// introducer can not yet remove messages
-		assertFalse(deleteAllMessages2From0());
+		assertFalse(deleteAllMessages2From0().allDeleted());
+		assertTrue(deleteAllMessages2From0().hasSessionInProgress());
 		// introducee2 can not yet remove messages
-		assertFalse(deleteAllMessages0From2());
+		assertFalse(deleteAllMessages0From2().allDeleted());
+		assertTrue(deleteAllMessages0From2().hasSessionInProgress());
 
 		// sync first ACCEPT message
 		sync1To0(1, true);
 		eventWaiter.await(TIMEOUT, 1);
 
 		// introducer can not yet remove messages
-		assertFalse(deleteAllMessages1From0());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages1From0().hasSessionInProgress());
 
 		// sync second ACCEPT message
 		sync2To0(1, true);
 		eventWaiter.await(TIMEOUT, 1);
 
 		// introducer can not yet remove messages
-		assertFalse(deleteAllMessages2From0());
+		assertFalse(deleteAllMessages2From0().allDeleted());
+		assertTrue(deleteAllMessages2From0().hasSessionInProgress());
 
 		// sync forwarded ACCEPT messages to introducees
 		sync0To1(1, true);
 		sync0To2(1, true);
 
 		// introducee1 can not yet remove messages
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 		// introducee2 can not yet remove messages
-		assertFalse(deleteAllMessages0From2());
+		assertFalse(deleteAllMessages0From2().allDeleted());
+		assertTrue(deleteAllMessages0From2().hasSessionInProgress());
 
 		// sync first AUTH and its forward
 		sync1To0(1, true);
 		sync0To2(1, true);
 
 		// introducer can not yet remove messages
-		assertFalse(deleteAllMessages1From0());
-		assertFalse(deleteAllMessages2From0());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages1From0().hasSessionInProgress());
+		assertFalse(deleteAllMessages2From0().allDeleted());
+		assertTrue(deleteAllMessages2From0().hasSessionInProgress());
 		// introducee2 can not yet remove messages
-		assertFalse(deleteAllMessages0From2());
+		assertFalse(deleteAllMessages0From2().allDeleted());
+		assertTrue(deleteAllMessages0From2().hasSessionInProgress());
 
 		// sync second AUTH and its forward as well as the following ACTIVATE
 		sync2To0(2, true);
 		sync0To1(2, true);
 
 		// introducer can not yet remove messages
-		assertFalse(deleteAllMessages1From0());
-		assertFalse(deleteAllMessages2From0());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages1From0().hasSessionInProgress());
+		assertFalse(deleteAllMessages2From0().allDeleted());
+		assertTrue(deleteAllMessages2From0().hasSessionInProgress());
 		// introducee1 can not yet remove messages
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 
 		// sync second ACTIVATE and its forward
 		sync1To0(1, true);
@@ -1221,13 +1238,15 @@ public class IntroductionIntegrationTest
 		assertGroupCount(messageTracker0, g1.getId(), 2, 1);
 
 		// introducer can now remove messages
-		assertTrue(deleteAllMessages1From0());
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
-		assertTrue(deleteAllMessages1From0());  // a second time returns true
+		// a second time returns true
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertGroupCount(messageTracker0, g1.getId(), 0, 0);
 
 		// introducee1 can not yet remove messages, because last not ACKed
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 		assertEquals(2, getMessages0From1().size());
 
 		// check that introducee1 messages are tracked properly
@@ -1237,18 +1256,20 @@ public class IntroductionIntegrationTest
 		sendAcks(c0, c1, contactId1From0, 1);
 
 		// introducee1 can now remove messages
-		assertTrue(deleteAllMessages0From1());
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertEquals(0, getMessages0From1().size());
-		assertTrue(deleteAllMessages0From1());  // a second time returns true
+		// a second time returns true
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertGroupCount(messageTracker1, g1.getId(), 0, 0);
 
 		// check that introducee2 messages are tracked properly
 		assertGroupCount(messageTracker2, g2.getId(), 2, 1);
 
 		// introducee2 can remove messages (last message was incoming)
-		assertTrue(deleteAllMessages0From2());
+		assertTrue(deleteAllMessages0From2().allDeleted());
 		assertEquals(0, getMessages0From2().size());
-		assertTrue(deleteAllMessages0From2());  // a second time returns true
+		// a second time returns true
+		assertTrue(deleteAllMessages0From2().allDeleted());
 		assertGroupCount(messageTracker2, g2.getId(), 0, 0);
 
 		// a new introduction is still possible
@@ -1271,10 +1292,14 @@ public class IntroductionIntegrationTest
 		assertFalse(listener2.aborted);
 
 		// nobody can delete anything again
-		assertFalse(deleteAllMessages1From0());
-		assertFalse(deleteAllMessages2From0());
-		assertFalse(deleteAllMessages0From1());
-		assertFalse(deleteAllMessages0From2());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages1From0().hasSessionInProgress());
+		assertFalse(deleteAllMessages2From0().allDeleted());
+		assertTrue(deleteAllMessages2From0().hasSessionInProgress());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
+		assertFalse(deleteAllMessages0From2().allDeleted());
+		assertTrue(deleteAllMessages0From2().hasSessionInProgress());
 
 		// group counts get counted up again correctly
 		assertGroupCount(messageTracker0, g1.getId(), 2, 1);
@@ -1302,50 +1327,54 @@ public class IntroductionIntegrationTest
 		eventWaiter.await(TIMEOUT, 1);
 
 		// introducer can not yet remove messages
-		assertFalse(deleteAllMessages1From0());
+		assertFalse(deleteAllMessages1From0().allDeleted());
 		// introducee1 can not yet remove messages
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
 
 		// sync second DECLINE message
 		sync2To0(1, true);
 		eventWaiter.await(TIMEOUT, 1);
 
 		// introducer can not yet remove messages
-		assertFalse(deleteAllMessages2From0());
+		assertFalse(deleteAllMessages2From0().allDeleted());
 		// introducee2 can not yet remove messages
-		assertFalse(deleteAllMessages0From2());
+		assertFalse(deleteAllMessages0From2().allDeleted());
 
 		// forward first DECLINE message
 		sync0To2(1, true);
 
 		// introducee2 can now remove messages
-		assertTrue(deleteAllMessages0From2());
+		assertTrue(deleteAllMessages0From2().allDeleted());
 		assertEquals(0, getMessages0From2().size());
-		assertTrue(deleteAllMessages0From2());  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteAllMessages0From2().allDeleted());
 
 		// forward second DECLINE message
 		sync0To1(1, true);
 
 		// introducee1 can now remove messages
-		assertTrue(deleteAllMessages0From1());
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertEquals(0, getMessages0From1().size());
-		assertTrue(deleteAllMessages0From1());  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteAllMessages0From1().allDeleted());
 
 		// introducer can not yet remove messages
-		assertFalse(deleteAllMessages1From0());
-		assertFalse(deleteAllMessages2From0());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertFalse(deleteAllMessages2From0().allDeleted());
 
 		// introducer can remove messages after getting ACK from introducee1
 		sendAcks(c1, c0, contactId0From1, 1);
-		assertTrue(deleteAllMessages1From0());
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
-		assertTrue(deleteAllMessages1From0());  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteAllMessages1From0().allDeleted());
 
 		// introducer can remove messages after getting ACK from introducee2
 		sendAcks(c2, c0, contactId0From2, 1);
-		assertTrue(deleteAllMessages2From0());
+		assertTrue(deleteAllMessages2From0().allDeleted());
 		assertEquals(0, getMessages2From0().size());
-		assertTrue(deleteAllMessages2From0());  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteAllMessages2From0().allDeleted());
 
 		// a new introduction is still possible
 		assertTrue(introductionManager0
@@ -1368,10 +1397,10 @@ public class IntroductionIntegrationTest
 		assertFalse(listener2.aborted);
 
 		// nobody can delete anything again
-		assertFalse(deleteAllMessages1From0());
-		assertFalse(deleteAllMessages2From0());
-		assertFalse(deleteAllMessages0From1());
-		assertFalse(deleteAllMessages0From2());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertFalse(deleteAllMessages2From0().allDeleted());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertFalse(deleteAllMessages0From2().allDeleted());
 	}
 
 	@Test
@@ -1401,9 +1430,10 @@ public class IntroductionIntegrationTest
 
 		// introducer can remove messages after getting ACK from introducee1
 		sendAcks(c1, c0, contactId0From1, 1);
-		assertTrue(deleteAllMessages1From0());
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
-		assertTrue(deleteAllMessages1From0());  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteAllMessages1From0().allDeleted());
 
 		// a new introduction is still possible
 		assertTrue(introductionManager0
@@ -1422,16 +1452,16 @@ public class IntroductionIntegrationTest
 
 		// introducer can remove messages after getting ACK from introducee1
 		sendAcks(c1, c0, contactId0From1, 1);
-		assertTrue(deleteAllMessages1From0());
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
-		assertTrue(deleteAllMessages1From0());  // a second time nothing happens
+		assertTrue(deleteAllMessages1From0().allDeleted());  // a second time nothing happens
 
 		// introducer can remove messages after getting ACK from introducee2
 		// if this succeeds, we still had the session object after delete above
 		sendAcks(c2, c0, contactId0From2, 1);
-		assertTrue(deleteAllMessages2From0());
+		assertTrue(deleteAllMessages2From0().allDeleted());
 		assertEquals(0, getMessages2From0().size());
-		assertTrue(deleteAllMessages2From0());  // a second time nothing happens
+		assertTrue(deleteAllMessages2From0().allDeleted());  // a second time nothing happens
 
 		// no one should have aborted
 		assertFalse(listener0.aborted);
@@ -1454,7 +1484,9 @@ public class IntroductionIntegrationTest
 		MessageId messageId1 = m1From0.iterator().next().getId();
 		Set<MessageId> toDelete1 = new HashSet<>();
 		toDelete1.add(messageId1);
-		assertFalse(deleteMessages1From0(toDelete1));
+		assertFalse(deleteMessages1From0(toDelete1).allDeleted());
+		assertTrue(deleteMessages1From0(toDelete1).hasIntroduction());
+		assertTrue(deleteMessages1From0(toDelete1).hasSessionInProgress());
 
 		// deleting the introduction for introducee2 will fail as well
 		Collection<ConversationMessageHeader> m2From0 = getMessages2From0();
@@ -1462,7 +1494,9 @@ public class IntroductionIntegrationTest
 		MessageId messageId2 = m2From0.iterator().next().getId();
 		Set<MessageId> toDelete2 = new HashSet<>();
 		toDelete2.add(messageId2);
-		assertFalse(deleteMessages2From0(toDelete2));
+		assertFalse(deleteMessages2From0(toDelete2).allDeleted());
+		assertTrue(deleteMessages2From0(toDelete2).hasIntroduction());
+		assertTrue(deleteMessages2From0(toDelete2).hasSessionInProgress());
 
 		// sync REQUEST messages
 		sync0To1(1, true);
@@ -1470,33 +1504,38 @@ public class IntroductionIntegrationTest
 		sync0To2(1, true);
 		eventWaiter.await(TIMEOUT, 1);
 
-		// deleting introduction fails for introducees,
-		// because response is not yet selected for deletion
-		assertFalse(deleteMessages0From1(toDelete1));
-		assertFalse(deleteMessages0From2(toDelete2));
+		// deleting introduction fails, because responses did not arrive
+		assertFalse(deleteMessages0From1(toDelete1).allDeleted());
+		assertTrue(deleteMessages0From1(toDelete1).hasSessionInProgress());
+		assertFalse(deleteMessages0From2(toDelete2).allDeleted());
+		assertTrue(deleteMessages0From2(toDelete2).hasSessionInProgress());
 
-		// add response of introducee1 for deletion
+		// remember response of introducee1 for future deletion
 		Collection<ConversationMessageHeader> m0From1 = getMessages0From1();
 		assertEquals(2, m0From1.size());
+		MessageId response1 = null;
 		for (ConversationMessageHeader h : m0From1) {
-			if (!h.getId().equals(messageId1)) toDelete1.add(h.getId());
+			if (!h.getId().equals(messageId1)) response1 = h.getId();
 		}
+		assertNotNull(response1);
 
-		// add response of introducee2 for deletion
+		// remember response of introducee2 for future deletion
 		Collection<ConversationMessageHeader> m0From2 = getMessages0From2();
 		assertEquals(2, m0From2.size());
+		MessageId response2 = null;
 		for (ConversationMessageHeader h : m0From2) {
-			if (!h.getId().equals(messageId2)) toDelete2.add(h.getId());
+			if (!h.getId().equals(messageId2)) response2 = h.getId();
 		}
+		assertNotNull(response2);
 
 		// sync first DECLINE message
 		sync1To0(1, true);
 		eventWaiter.await(TIMEOUT, 1);
 
 		// introducer can not yet remove messages
-		assertFalse(deleteMessages1From0(toDelete1));
+		assertFalse(deleteMessages1From0(toDelete1).allDeleted());
 		// introducee1 can not yet remove messages
-		assertFalse(deleteMessages0From1(toDelete1));
+		assertFalse(deleteMessages0From1(toDelete1).allDeleted());
 
 		// sync second DECLINE message
 		sync2To0(1, true);
@@ -1508,77 +1547,104 @@ public class IntroductionIntegrationTest
 		assertGroupCount(messageTracker1, g1.getId(), 2, 1);
 		assertGroupCount(messageTracker2, g2.getId(), 2, 1);
 
-		// introducer can now remove messages with both introducees
-		assertTrue(deleteMessages1From0(toDelete1));
-		assertTrue(deleteMessages2From0(toDelete2));
+		// introducer can now remove messages with both introducees,
+		// if the responses are also selected
+		Set<MessageId> toDelete1From0 = new HashSet<>(toDelete1);
+		toDelete1From0.add(response1);
+		DeletionResult result = deleteMessages1From0(toDelete1From0);
+		assertTrue(result.allDeleted());
+		Set<MessageId> toDelete2From0 = new HashSet<>(toDelete2);
+		toDelete2From0.add(response2);
+		assertTrue(deleteMessages2From0(toDelete2From0).allDeleted());
 		assertGroupCount(messageTracker0, g1.getId(), 0, 0);
 		assertGroupCount(messageTracker0, g2.getId(), 0, 0);
+
 		// introducee2 can not yet remove messages, missing the other response
-		assertFalse(deleteMessages0From1(toDelete1));
+		assertFalse(deleteMessages0From1(toDelete1).allDeleted());
 
 		// forward first DECLINE message
 		sync0To2(1, true);
 
+		// deleting introduction fails for introducee 2,
+		// because response is not yet selected for deletion
+		assertFalse(deleteMessages0From2(toDelete2).allDeleted());
+		assertTrue(deleteMessages0From2(toDelete2).hasIntroduction());
+		assertTrue(deleteMessages0From2(toDelete2).hasNotAllSelected());
+
+		// add response to be deleted as well
+		toDelete2.add(response2);
+
 		// introducee2 can now remove messages
-		assertTrue(deleteMessages0From2(toDelete2));
+		assertTrue(deleteMessages0From2(toDelete2).allDeleted());
 		assertEquals(0, getMessages0From2().size());
-		assertTrue(deleteMessages0From2(toDelete2));  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteMessages0From2(toDelete2).allDeleted());
 		assertGroupCount(messageTracker2, g2.getId(), 0, 0);
 
 		// forward second DECLINE message
 		sync0To1(1, true);
 
+		// deleting introduction fails for introducee 1,
+		// because response is not yet selected for deletion
+		assertFalse(deleteMessages0From1(toDelete1).allDeleted());
+		assertTrue(deleteMessages0From1(toDelete1).hasIntroduction());
+		assertTrue(deleteMessages0From1(toDelete1).hasNotAllSelected());
+
+		// add response to be deleted as well
+		toDelete1.add(response1);
+
 		// introducee1 can now also remove messages
-		assertTrue(deleteMessages0From1(toDelete1));
+		assertTrue(deleteMessages0From1(toDelete1).allDeleted());
 		assertEquals(0, getMessages0From1().size());
-		assertTrue(deleteMessages0From1(toDelete1));  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteMessages0From1(toDelete1).allDeleted());
 		assertGroupCount(messageTracker1, g1.getId(), 0, 0);
 	}
 
 	@Test
 	public void testDeletingEmptySet() throws Exception {
-		assertTrue(deleteMessages0From1(emptySet()));
+		assertTrue(deleteMessages0From1(emptySet()).allDeleted());
 	}
 
-	private boolean deleteAllMessages1From0() throws DbException {
+	private DeletionResult deleteAllMessages1From0() throws DbException {
 		return db0.transactionWithResult(false, txn -> introductionManager0
 				.deleteAllMessages(txn, contactId1From0));
 	}
 
-	private boolean deleteAllMessages2From0() throws DbException {
+	private DeletionResult deleteAllMessages2From0() throws DbException {
 		return db0.transactionWithResult(false, txn -> introductionManager0
 				.deleteAllMessages(txn, contactId2From0));
 	}
 
-	private boolean deleteAllMessages0From1() throws DbException {
+	private DeletionResult deleteAllMessages0From1() throws DbException {
 		return db1.transactionWithResult(false, txn -> introductionManager1
 				.deleteAllMessages(txn, contactId0From1));
 	}
 
-	private boolean deleteAllMessages0From2() throws DbException {
+	private DeletionResult deleteAllMessages0From2() throws DbException {
 		return db2.transactionWithResult(false, txn -> introductionManager2
 				.deleteAllMessages(txn, contactId0From2));
 	}
 
-	private boolean deleteMessages1From0(Set<MessageId> toDelete)
+	private DeletionResult deleteMessages1From0(Set<MessageId> toDelete)
 			throws DbException {
 		return db0.transactionWithResult(false, txn -> introductionManager0
 				.deleteMessages(txn, contactId1From0, toDelete));
 	}
 
-	private boolean deleteMessages2From0(Set<MessageId> toDelete)
+	private DeletionResult deleteMessages2From0(Set<MessageId> toDelete)
 			throws DbException {
 		return db0.transactionWithResult(false, txn -> introductionManager0
 				.deleteMessages(txn, contactId2From0, toDelete));
 	}
 
-	private boolean deleteMessages0From1(Set<MessageId> toDelete)
+	private DeletionResult deleteMessages0From1(Set<MessageId> toDelete)
 			throws DbException {
 		return db1.transactionWithResult(false, txn -> introductionManager1
 				.deleteMessages(txn, contactId0From1, toDelete));
 	}
 
-	private boolean deleteMessages0From2(Set<MessageId> toDelete)
+	private DeletionResult deleteMessages0From2(Set<MessageId> toDelete)
 			throws DbException {
 		return db2.transactionWithResult(false, txn -> introductionManager2
 				.deleteMessages(txn, contactId0From2, toDelete));

briar-core/src/test/java/org/briarproject/briar/messaging/MessagingManagerIntegrationTest.java

@@ -7,6 +7,7 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.test.TestDatabaseConfigModule;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessage;
@@ -159,9 +160,11 @@ public class MessagingManagerIntegrationTest
 
 		// delete all messages on both sides (deletes all, because returns true)
 		assertTrue(db0.transactionWithResult(false,
-				txn -> messagingManager0.deleteAllMessages(txn, contactId)));
+				txn -> messagingManager0.deleteAllMessages(txn, contactId))
+				.allDeleted());
 		assertTrue(db1.transactionWithResult(false,
-				txn -> messagingManager1.deleteAllMessages(txn, contactId)));
+				txn -> messagingManager1.deleteAllMessages(txn, contactId))
+				.allDeleted());
 
 		// all messages are gone
 		assertEquals(0, getMessages(c0).size());
@@ -185,9 +188,11 @@ public class MessagingManagerIntegrationTest
 		toDelete.add(m1.getMessage().getId());
 		toDelete.add(m2.getMessage().getId());
 		assertTrue(db0.transactionWithResult(false, txn ->
-				messagingManager0.deleteMessages(txn, contactId, toDelete)));
+				messagingManager0.deleteMessages(txn, contactId, toDelete))
+				.allDeleted());
 		assertTrue(db1.transactionWithResult(false, txn ->
-				messagingManager1.deleteMessages(txn, contactId, toDelete)));
+				messagingManager1.deleteMessages(txn, contactId, toDelete))
+				.allDeleted());
 
 		// all messages except 1 are gone
 		assertEquals(1, getMessages(c0).size());
@@ -203,7 +208,8 @@ public class MessagingManagerIntegrationTest
 		toDelete.clear();
 		toDelete.add(m0.getMessage().getId());
 		assertTrue(db0.transactionWithResult(false, txn ->
-				messagingManager0.deleteMessages(txn, contactId, toDelete)));
+				messagingManager0.deleteMessages(txn, contactId, toDelete))
+				.allDeleted());
 		assertEquals(0, getMessages(c0).size());
 		assertGroupCounts(c0, 0, 0);
 	}
@@ -225,9 +231,9 @@ public class MessagingManagerIntegrationTest
 		Set<MessageId> toDelete = new HashSet<>();
 		toDelete.add(m0.getMessage().getId());
 		assertTrue(c0.getConversationManager()
-				.deleteMessages(contactId, toDelete));
+				.deleteMessages(contactId, toDelete).allDeleted());
 		assertTrue(c1.getConversationManager()
-				.deleteMessages(contactId, toDelete));
+				.deleteMessages(contactId, toDelete).allDeleted());
 
 		// message was deleted
 		assertEquals(0, getMessages(c0).size());
@@ -246,9 +252,11 @@ public class MessagingManagerIntegrationTest
 
 		// delete message on both sides (deletes all, because returns true)
 		assertTrue(db0.transactionWithResult(false,
-				txn -> messagingManager0.deleteAllMessages(txn, contactId)));
+				txn -> messagingManager0.deleteAllMessages(txn, contactId))
+				.allDeleted());
 		assertTrue(db1.transactionWithResult(false,
-				txn -> messagingManager1.deleteAllMessages(txn, contactId)));
+				txn -> messagingManager1.deleteAllMessages(txn, contactId))
+				.allDeleted());
 
 		// attachment was deleted on both devices
 		try {
@@ -285,10 +293,14 @@ public class MessagingManagerIntegrationTest
 		// deleting message fails (on both sides),
 		// because attachment is not yet delivered
 		Set<MessageId> toDelete = singleton(m.getMessage().getId());
-		assertFalse(db0.transactionWithResult(false, txn ->
-				messagingManager0.deleteMessages(txn, contactId, toDelete)));
-		assertFalse(db1.transactionWithResult(false, txn ->
-				messagingManager1.deleteMessages(txn, contactId, toDelete)));
+		DeletionResult result0 = db0.transactionWithResult(false, txn ->
+				messagingManager0.deleteMessages(txn, contactId, toDelete));
+		assertFalse(result0.allDeleted());
+		assertTrue(result0.hasNotFullyDownloaded());
+		DeletionResult result1 = db1.transactionWithResult(false, txn ->
+				messagingManager1.deleteMessages(txn, contactId, toDelete));
+		assertFalse(result1.allDeleted());
+		assertTrue(result1.hasNotFullyDownloaded());
 
 		// deliver attachment
 		db0.transaction(false,
@@ -298,9 +310,11 @@ public class MessagingManagerIntegrationTest
 
 		// deleting message and attachment on both sides works now
 		assertTrue(db0.transactionWithResult(false, txn ->
-				messagingManager0.deleteMessages(txn, contactId, toDelete)));
+				messagingManager0.deleteMessages(txn, contactId, toDelete))
+				.allDeleted());
 		assertTrue(db1.transactionWithResult(false, txn ->
-				messagingManager1.deleteMessages(txn, contactId, toDelete)));
+				messagingManager1.deleteMessages(txn, contactId, toDelete))
+				.allDeleted());
 
 		// attachment was deleted on both devices
 		try {
@@ -320,7 +334,8 @@ public class MessagingManagerIntegrationTest
 	@Test
 	public void testDeletingEmptySet() throws Exception {
 		assertTrue(db0.transactionWithResult(false, txn ->
-				messagingManager0.deleteMessages(txn, contactId, emptySet())));
+				messagingManager0.deleteMessages(txn, contactId, emptySet()))
+				.allDeleted());
 	}
 
 	private PrivateMessage sendMessage(BriarIntegrationTestComponent from,

briar-core/src/test/java/org/briarproject/briar/privategroup/invitation/GroupInvitationIntegrationTest.java

@@ -6,6 +6,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.test.TestDatabaseConfigModule;
 import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.privategroup.GroupMessage;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
 import org.briarproject.briar.api.privategroup.PrivateGroupManager;
@@ -463,9 +464,13 @@ public class GroupInvitationIntegrationTest
 		sync0To1(1, true);
 
 		// messages can not be deleted
-		assertFalse(deleteAllMessages1From0());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages1From0().hasInvitation());
+		assertTrue(deleteAllMessages1From0().hasSessionInProgress());
 		assertEquals(1, getMessages1From0().size());
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasInvitation());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 		assertEquals(1, getMessages0From1().size());
 
 		// respond
@@ -478,13 +483,15 @@ public class GroupInvitationIntegrationTest
 		assertGroupCount(messageTracker1, g0From1.getId(), 2, 1);
 
 		// messages can be deleted now by creator, invitee needs to wait for ACK
-		assertTrue(deleteAllMessages1From0());
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
-		assertTrue(deleteAllMessages1From0());  // a second time nothing happens
+		assertTrue(deleteAllMessages1From0().allDeleted());  // a second time nothing happens
 		assertGroupCount(messageTracker0, g1From0.getId(), 0, 0);
 
 		// trying to delete fails for invitee
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasInvitation());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 		assertEquals(2, getMessages0From1().size());
 
 		// creator sends two JOIN messages (one sharing + one in private group)
@@ -492,9 +499,10 @@ public class GroupInvitationIntegrationTest
 		sync0To1(2, true);
 
 		// now invitee can also delete messages
-		assertTrue(deleteAllMessages0From1());
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertEquals(0, getMessages0From1().size());
-		assertTrue(deleteAllMessages0From1());  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertGroupCount(messageTracker1, g0From1.getId(), 0, 0);
 
 		// invitee now leaves
@@ -524,21 +532,25 @@ public class GroupInvitationIntegrationTest
 		assertGroupCount(messageTracker1, g0From1.getId(), 2, 1);
 
 		// messages can be deleted now by creator, invitee needs to wait for ACK
-		assertTrue(deleteAllMessages1From0());
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
-		assertTrue(deleteAllMessages1From0());  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteAllMessages1From0().allDeleted());
 
 		// trying to delete fails for invitee
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasInvitation());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 		assertEquals(2, getMessages0From1().size());
 
 		// creator sends ACK
 		sendAcks(c0, c1, contactId1From0, 1);
 
 		// now invitee can also delete messages
-		assertTrue(deleteAllMessages0From1());
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertEquals(0, getMessages0From1().size());
-		assertTrue(deleteAllMessages0From1());  // a second time nothing happens
+		// a second time nothing happens
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertGroupCount(messageTracker1, g0From1.getId(), 0, 0);
 
 		// creator can re-invite
@@ -546,8 +558,10 @@ public class GroupInvitationIntegrationTest
 		sync0To1(1, true);
 
 		// now new messages can not be deleted anymore
-		assertFalse(deleteAllMessages1From0());
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages1From0().hasSessionInProgress());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 
 		// responding again
 		groupInvitationManager1
@@ -562,8 +576,8 @@ public class GroupInvitationIntegrationTest
 		assertGroupCount(messageTracker0, g1From0.getId(), 2, 1);
 
 		// deleting is possible again
-		assertTrue(deleteAllMessages1From0());
-		assertTrue(deleteAllMessages0From1());
+		assertTrue(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertGroupCount(messageTracker1, g0From1.getId(), 0, 0);
 		assertGroupCount(messageTracker0, g1From0.getId(), 0, 0);
 	}
@@ -580,8 +594,10 @@ public class GroupInvitationIntegrationTest
 		MessageId messageId = m0.iterator().next().getId();
 		Set<MessageId> toDelete = new HashSet<>();
 		toDelete.add(messageId);
-		assertFalse(deleteMessages1From0(toDelete));
-		assertFalse(deleteMessages0From1(toDelete));
+		assertFalse(deleteMessages1From0(toDelete).allDeleted());
+		assertTrue(deleteMessages1From0(toDelete).hasSessionInProgress());
+		assertFalse(deleteMessages0From1(toDelete).allDeleted());
+		assertTrue(deleteMessages0From1(toDelete).hasSessionInProgress());
 
 		// respond
 		groupInvitationManager1
@@ -590,8 +606,10 @@ public class GroupInvitationIntegrationTest
 
 		// both can still not delete the invitation,
 		// because the response was not selected for deletion as well
-		assertFalse(deleteMessages1From0(toDelete));
-		assertFalse(deleteMessages0From1(toDelete));
+		assertFalse(deleteMessages1From0(toDelete).allDeleted());
+		assertTrue(deleteMessages1From0(toDelete).hasNotAllSelected());
+		assertFalse(deleteMessages0From1(toDelete).allDeleted());
+		assertTrue(deleteMessages0From1(toDelete).hasNotAllSelected());
 
 		// after selecting response, both messages can be deleted by creator
 		m0 = getMessages1From0();
@@ -600,14 +618,15 @@ public class GroupInvitationIntegrationTest
 			if (!h.getId().equals(messageId)) toDelete.add(h.getId());
 		}
 		assertGroupCount(messageTracker0, g1From0.getId(), 2, 1);
-		assertTrue(deleteMessages1From0(toDelete));
+		assertTrue(deleteMessages1From0(toDelete).allDeleted());
 		assertEquals(0, getMessages1From0().size());
 		// a second time nothing happens
-		assertTrue(deleteMessages1From0(toDelete));
+		assertTrue(deleteMessages1From0(toDelete).allDeleted());
 		assertGroupCount(messageTracker0, g1From0.getId(), 0, 0);
 
 		// 1 can still not delete the messages, as last one has not been ACKed
-		assertFalse(deleteMessages0From1(toDelete));
+		assertFalse(deleteMessages0From1(toDelete).allDeleted());
+		assertTrue(deleteMessages0From1(toDelete).hasSessionInProgress());
 		assertEquals(2, getMessages0From1().size());
 		assertGroupCount(messageTracker1, g0From1.getId(), 2, 1);
 
@@ -615,16 +634,16 @@ public class GroupInvitationIntegrationTest
 		sendAcks(c0, c1, contactId1From0, 1);
 
 		// 1 can now delete all messages, as last one has been ACKed
-		assertTrue(deleteMessages0From1(toDelete));
+		assertTrue(deleteMessages0From1(toDelete).allDeleted());
 		assertEquals(0, getMessages0From1().size());
 		assertGroupCount(messageTracker1, g0From1.getId(), 0, 0);
 		// a second time nothing happens
-		assertTrue(deleteMessages0From1(toDelete));
+		assertTrue(deleteMessages0From1(toDelete).allDeleted());
 	}
 
 	@Test
 	public void testDeletingEmptySet() throws Exception {
-		assertTrue(deleteMessages0From1(emptySet()));
+		assertTrue(deleteMessages0From1(emptySet()).allDeleted());
 	}
 
 	private Collection<ConversationMessageHeader> getMessages1From0()
@@ -639,23 +658,23 @@ public class GroupInvitationIntegrationTest
 				.getMessageHeaders(txn, contactId0From1));
 	}
 
-	private boolean deleteAllMessages1From0() throws DbException {
+	private DeletionResult deleteAllMessages1From0() throws DbException {
 		return db0.transactionWithResult(false, txn -> groupInvitationManager0
 				.deleteAllMessages(txn, contactId1From0));
 	}
 
-	private boolean deleteAllMessages0From1() throws DbException {
+	private DeletionResult deleteAllMessages0From1() throws DbException {
 		return db1.transactionWithResult(false, txn -> groupInvitationManager1
 				.deleteAllMessages(txn, contactId0From1));
 	}
 
-	private boolean deleteMessages1From0(Set<MessageId> toDelete)
+	private DeletionResult deleteMessages1From0(Set<MessageId> toDelete)
 			throws DbException {
 		return db0.transactionWithResult(false, txn -> groupInvitationManager0
 				.deleteMessages(txn, contactId1From0, toDelete));
 	}
 
-	private boolean deleteMessages0From1(Set<MessageId> toDelete)
+	private DeletionResult deleteMessages0From1(Set<MessageId> toDelete)
 			throws DbException {
 		return db1.transactionWithResult(false, txn -> groupInvitationManager1
 				.deleteMessages(txn, contactId0From1, toDelete));

briar-core/src/test/java/org/briarproject/briar/sharing/ForumSharingIntegrationTest.java

@@ -16,6 +16,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.test.TestDatabaseConfigModule;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
 import org.briarproject.briar.api.conversation.ConversationResponse;
+import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.forum.Forum;
 import org.briarproject.briar.api.forum.ForumInvitationRequest;
 import org.briarproject.briar.api.forum.ForumInvitationResponse;
@@ -864,8 +865,12 @@ public class ForumSharingIntegrationTest
 		eventWaiter.await(TIMEOUT, 1);
 
 		// messages can not be deleted
-		assertFalse(deleteAllMessages1From0());
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages1From0().hasInvitation());
+		assertTrue(deleteAllMessages1From0().hasSessionInProgress());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasInvitation());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 
 		// accept invitation
 		respondToRequest(contactId0From1, true);
@@ -881,19 +886,20 @@ public class ForumSharingIntegrationTest
 		assertGroupCount(messageTracker1, g0From1, 2, 1);
 
 		// 0 deletes all messages
-		assertTrue(deleteAllMessages1From0());
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
 		assertGroupCount(messageTracker0, g1From0, 0, 0);
 
 		// 1 can not delete all messages, as last one has not been ACKed
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 		assertGroupCount(messageTracker1, g0From1, 2, 1);
 
 		// 0 sends an ACK to their last message
 		sendAcks(c0, c1, contactId1From0, 1);
 
 		// 1 can now delete all messages, as last one has been ACKed
-		assertTrue(deleteAllMessages0From1());
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertEquals(0, getMessages0From1().size());
 		assertGroupCount(messageTracker1, g0From1, 0, 0);
 
@@ -911,10 +917,12 @@ public class ForumSharingIntegrationTest
 		eventWaiter.await(TIMEOUT, 1);
 
 		// messages can not be deleted anymore
-		assertFalse(deleteAllMessages1From0());
+		assertFalse(deleteAllMessages1From0().allDeleted());
+		assertTrue(deleteAllMessages1From0().hasSessionInProgress());
 		assertEquals(1, getMessages1From0().size());
 		assertGroupCount(messageTracker0, g1From0, 1, 1);
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
+		assertTrue(deleteAllMessages0From1().hasSessionInProgress());
 		assertEquals(1, getMessages0From1().size());
 		assertGroupCount(messageTracker1, g0From1, 1, 0);
 
@@ -926,10 +934,10 @@ public class ForumSharingIntegrationTest
 		sendAcks(c1, c0, contactId0From1, 1);
 
 		// messages can now get deleted again
-		assertTrue(deleteAllMessages1From0());
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
 		assertGroupCount(messageTracker0, g1From0, 0, 0);
-		assertTrue(deleteAllMessages0From1());
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertEquals(0, getMessages0From1().size());
 		assertGroupCount(messageTracker1, g0From1, 0, 0);
 	}
@@ -949,17 +957,17 @@ public class ForumSharingIntegrationTest
 		eventWaiter.await(TIMEOUT, 1);
 
 		// 0 deletes all messages
-		assertTrue(deleteAllMessages1From0());
+		assertTrue(deleteAllMessages1From0().allDeleted());
 		assertEquals(0, getMessages1From0().size());
 
 		// 1 can not delete all messages, as last one has not been ACKed
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
 
 		// 0 sends an ACK to their last message
 		sendAcks(c0, c1, contactId1From0, 1);
 
 		// 1 can now delete all messages, as last one has been ACKed
-		assertTrue(deleteAllMessages0From1());
+		assertTrue(deleteAllMessages0From1().allDeleted());
 		assertEquals(0, getMessages0From1().size());
 
 		// re-sending invitation is possible
@@ -969,9 +977,9 @@ public class ForumSharingIntegrationTest
 		eventWaiter.await(TIMEOUT, 1);
 
 		// messages can not be deleted anymore
-		assertFalse(deleteAllMessages1From0());
+		assertFalse(deleteAllMessages1From0().allDeleted());
 		assertEquals(1, getMessages1From0().size());
-		assertFalse(deleteAllMessages0From1());
+		assertFalse(deleteAllMessages0From1().allDeleted());
 		assertEquals(1, getMessages0From1().size());
 	}
 
@@ -989,7 +997,9 @@ public class ForumSharingIntegrationTest
 		MessageId messageId = m0.iterator().next().getId();
 		Set<MessageId> toDelete = new HashSet<>();
 		toDelete.add(messageId);
-		assertFalse(deleteMessages1From0(toDelete));
+		assertFalse(deleteMessages1From0(toDelete).allDeleted());
+		assertTrue(deleteMessages1From0(toDelete).hasInvitation());
+		assertTrue(deleteMessages1From0(toDelete).hasSessionInProgress());
 
 		// decline invitation
 		respondToRequest(contactId0From1, true);
@@ -998,8 +1008,12 @@ public class ForumSharingIntegrationTest
 
 		// both can still not delete the invitation,
 		// because the response was not selected for deletion as well
-		assertFalse(deleteMessages1From0(toDelete));
-		assertFalse(deleteMessages0From1(toDelete));
+		assertFalse(deleteMessages1From0(toDelete).allDeleted());
+		assertTrue(deleteMessages1From0(toDelete).hasInvitation());
+		assertTrue(deleteMessages1From0(toDelete).hasNotAllSelected());
+		assertFalse(deleteMessages0From1(toDelete).allDeleted());
+		assertTrue(deleteMessages0From1(toDelete).hasInvitation());
+		assertTrue(deleteMessages0From1(toDelete).hasNotAllSelected());
 
 		// after selecting response, both messages can be deleted
 		m0 = getMessages1From0();
@@ -1007,27 +1021,30 @@ public class ForumSharingIntegrationTest
 		for (ConversationMessageHeader h : m0) {
 			if (!h.getId().equals(messageId)) toDelete.add(h.getId());
 		}
-		assertTrue(deleteMessages1From0(toDelete));
+		assertTrue(deleteMessages1From0(toDelete).allDeleted());
 		assertEquals(0, getMessages1From0().size());
 		// a second time nothing happens
-		assertTrue(deleteMessages1From0(toDelete));
+		assertTrue(deleteMessages1From0(toDelete).allDeleted());
 
 		// 1 can still not delete the messages, as last one has not been ACKed
-		assertFalse(deleteMessages0From1(toDelete));
+		assertFalse(deleteMessages0From1(toDelete).allDeleted());
+		assertFalse(deleteMessages0From1(toDelete).hasNotAllSelected());
+		assertTrue(deleteMessages0From1(toDelete).hasInvitation());
+		assertTrue(deleteMessages0From1(toDelete).hasSessionInProgress());
 
 		// 0 sends an ACK to their last message
 		sendAcks(c0, c1, contactId1From0, 1);
 
 		// 1 can now delete all messages, as last one has been ACKed
-		assertTrue(deleteMessages0From1(toDelete));
+		assertTrue(deleteMessages0From1(toDelete).allDeleted());
 		assertEquals(0, getMessages0From1().size());
 		// a second time nothing happens
-		assertTrue(deleteMessages0From1(toDelete));
+		assertTrue(deleteMessages0From1(toDelete).allDeleted());
 	}
 
 	@Test
 	public void testDeletingEmptySet() throws Exception {
-		assertTrue(deleteMessages0From1(emptySet()));
+		assertTrue(deleteMessages0From1(emptySet()).allDeleted());
 	}
 
 	private Collection<ConversationMessageHeader> getMessages1From0()
@@ -1042,23 +1059,23 @@ public class ForumSharingIntegrationTest
 				.getMessageHeaders(txn, contactId0From1));
 	}
 
-	private boolean deleteAllMessages1From0() throws DbException {
+	private DeletionResult deleteAllMessages1From0() throws DbException {
 		return db0.transactionWithResult(false, txn -> forumSharingManager0
 				.deleteAllMessages(txn, contactId1From0));
 	}
 
-	private boolean deleteAllMessages0From1() throws DbException {
+	private DeletionResult deleteAllMessages0From1() throws DbException {
 		return db1.transactionWithResult(false, txn -> forumSharingManager1
 				.deleteAllMessages(txn, contactId0From1));
 	}
 
-	private boolean deleteMessages1From0(Set<MessageId> toDelete)
+	private DeletionResult deleteMessages1From0(Set<MessageId> toDelete)
 			throws DbException {
 		return db0.transactionWithResult(false, txn -> forumSharingManager0
 				.deleteMessages(txn, contactId1From0, toDelete));
 	}
 
-	private boolean deleteMessages0From1(Set<MessageId> toDelete)
+	private DeletionResult deleteMessages0From1(Set<MessageId> toDelete)
 			throws DbException {
 		return db1.transactionWithResult(false, txn -> forumSharingManager1
 				.deleteMessages(txn, contactId0From1, toDelete));