Add a bunch of tests highlighting implicit acks

Automatically decline incoming blog/forum invitations when they self-destruct

See merge request briar/briar!1392

.gitlab-ci.yml

@@ -1,52 +1,30 @@
 image: briar/ci-image-android:latest
 
 stages:
-  - test
+- test
-  - optional_tests
+- optional_tests
-  - check_reproducibility
+- check_reproducibility
 
-.base-test:
+test:
+  stage: test
   before_script:
     - set -e
     - export GRADLE_USER_HOME=$PWD/.gradle
+
   cache:
-    key: "$CI_COMMIT_REF_SLUG"
     paths:
       - .gradle/wrapper
       - .gradle/caches
+
+  script:
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check compileOfficialDebugAndroidTestSources compileScreenshotDebugAndroidTestSources
+
   after_script:
-    # these file change every time and should not be cached
+    # these file change every time but should not be cached
     - rm -f $GRADLE_USER_HOME/caches/modules-2/modules-2.lock
     - rm -fr $GRADLE_USER_HOME/caches/*/plugin-resolution/
 
-test:
-  extends: .base-test
-  stage: test
-  script:
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check
-
-android test:
-  extends: .base-test
-  stage: optional_tests
-  image: briar/ci-image-android-emulator:latest
-  script:
-    # start emulator first, so it can fail early
-    - start-emulator.sh
-    # run normal and screenshot tests together (exclude Large tests)
-    - ./gradlew -Djava.security.egd=file:/dev/urandom connectedAndroidTest -Pandroid.testInstrumentationRunnerArguments.notAnnotation=androidx.test.filters.LargeTest
-  artifacts:
-    name: "${CI_PROJECT_PATH}_${CI_JOB_STAGE}_${CI_COMMIT_REF_NAME}_${CI_COMMIT_SHA}"
-    paths:
-      - kernel.log
-      - logcat.txt
-    expire_in: 3 days
-    when: on_failure
-  when: manual
-  except:
-    - tags
-  tags:
-    - kvm
 
 test_reproducible:
   stage: check_reproducibility
@@ -62,7 +40,6 @@ test_reproducible:
     - export GRADLE_USER_HOME=$PWD/.gradle
 
   cache:
-    key: "$CI_COMMIT_REF_SLUG"
     paths:
       - .gradle/wrapper
       - .gradle/caches

.idea/dictionaries/briar.xml

@@ -7,6 +7,7 @@
       <w>encrypter</w>
       <w>identicon</w>
       <w>introducee</w>
+      <w>introducees</w>
       <w>introducer</w>
       <w>onboarding</w>
     </words>

.idea/runConfigurations/Instrumentation_Tests__destroys_DB_.xml

@@ -1,51 +0,0 @@
-<component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="Instrumentation Tests (destroys DB)" type="AndroidTestRunConfigurationType" factoryName="Android Instrumented Tests">
-    <module name="briar.briar-android" />
-    <option name="TESTING_TYPE" value="1" />
-    <option name="METHOD_NAME" value="" />
-    <option name="CLASS_NAME" value="" />
-    <option name="PACKAGE_NAME" value="org.briarproject.briar.android" />
-    <option name="INSTRUMENTATION_RUNNER_CLASS" value="" />
-    <option name="EXTRA_OPTIONS" value="-e notAnnotation androidx.test.filters.LargeTest" />
-    <option name="INCLUDE_GRADLE_EXTRA_OPTIONS" value="true" />
-    <option name="CLEAR_LOGCAT" value="false" />
-    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
-    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
-    <option name="FORCE_STOP_RUNNING_APP" value="true" />
-    <option name="TARGET_SELECTION_MODE" value="DEVICE_AND_SNAPSHOT_COMBO_BOX" />
-    <option name="DEBUGGER_TYPE" value="Auto" />
-    <Auto>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Auto>
-    <Hybrid>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Hybrid>
-    <Java />
-    <Native>
-      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
-      <option name="SHOW_STATIC_VARS" value="true" />
-      <option name="WORKING_DIR" value="" />
-      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
-      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
-    </Native>
-    <Profilers>
-      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
-      <option name="STARTUP_PROFILING_ENABLED" value="false" />
-      <option name="STARTUP_CPU_PROFILING_ENABLED" value="false" />
-      <option name="STARTUP_CPU_PROFILING_CONFIGURATION_NAME" value="Sample Java Methods" />
-      <option name="STARTUP_NATIVE_MEMORY_PROFILING_ENABLED" value="false" />
-      <option name="NATIVE_MEMORY_SAMPLE_RATE_BYTES" value="2048" />
-    </Profilers>
-    <method v="2">
-      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-    </method>
-  </configuration>
-</component>

bramble-android/build.gradle

@@ -8,15 +8,11 @@ android {
 	compileSdkVersion 30
 	buildToolsVersion '30.0.2'
 
-	packagingOptions {
-		doNotStrip '**/*.so'
-	}
-
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 29
-		versionCode 10220
+		versionCode 10216
-		versionName "1.2.20"
+		versionName "1.2.16"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPlugin.java

@@ -175,11 +175,6 @@ class AndroidBluetoothPlugin
 		} catch (IOException e) {
 			IoUtils.tryToClose(s, LOG, WARNING);
 			throw e;
-		} catch (NullPointerException e) {
-			// BluetoothSocket#connect() may throw an NPE under unknown
-			// circumstances
-			IoUtils.tryToClose(s, LOG, WARNING);
-			throw new IOException(e);
 		}
 	}
 

bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java

@@ -114,8 +114,12 @@ public class AndroidUtils {
 
 	/**
 	 * Returns an array of supported content types for image attachments.
+	 * GIFs can't be compressed on API < 24 so they're not supported.
+	 * <p>
+	 * TODO: Remove this restriction when large message support is added
 	 */
 	public static String[] getSupportedImageContentTypes() {
-		return new String[] {"image/jpeg", "image/png", "image/gif"};
+		if (SDK_INT < 24) return new String[] {"image/jpeg", "image/png"};
+		else return new String[] {"image/jpeg", "image/png", "image/gif"};
 	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/FeatureFlags.java

@@ -9,4 +9,5 @@ public interface FeatureFlags {
 
 	boolean shouldEnableProfilePictures();
 
+	boolean shouldEnableDisappearingMessages();
 }

bramble-api/src/main/java/org/briarproject/bramble/api/cleanup/CleanupHook.java

@@ -0,0 +1,29 @@
+package org.briarproject.bramble.api.cleanup;
+
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+
+import java.util.Collection;
+
+/**
+ * An interface for registering a hook with the {@link CleanupManager}
+ * that will be called when a message's cleanup deadline is reached.
+ */
+@NotNullByDefault
+public interface CleanupHook {
+
+	/**
+	 * Called when the cleanup deadlines of one or more messages are reached.
+	 * <p>
+	 * The callee is not required to delete the messages, but the hook won't be
+	 * called again for these messages unless another cleanup timer is set (see
+	 * {@link DatabaseComponent#setCleanupTimerDuration(Transaction, MessageId, long)}
+	 * and {@link DatabaseComponent#startCleanupTimer(Transaction, MessageId)}).
+	 */
+	void deleteMessages(Transaction txn, GroupId g,
+			Collection<MessageId> messageIds) throws DbException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/cleanup/CleanupManager.java

@@ -0,0 +1,42 @@
+package org.briarproject.bramble.api.cleanup;
+
+import org.briarproject.bramble.api.cleanup.event.CleanupTimerStartedEvent;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.ClientId;
+import org.briarproject.bramble.api.sync.MessageId;
+
+/**
+ * The CleanupManager is responsible for tracking the cleanup deadlines of
+ * messages and passing them to their respective
+ * {@link CleanupHook CleanupHooks} when the deadlines are reached.
+ * <p>
+ * The CleanupManager responds to
+ * {@link CleanupTimerStartedEvent CleanupTimerStartedEvents} broadcast by the
+ * {@link DatabaseComponent}.
+ * <p>
+ * See {@link DatabaseComponent#setCleanupTimerDuration(Transaction, MessageId, long)},
+ * {@link DatabaseComponent#startCleanupTimer(Transaction, MessageId)},
+ * {@link DatabaseComponent#stopCleanupTimer(Transaction, MessageId)}.
+ */
+@NotNullByDefault
+public interface CleanupManager {
+
+	/**
+	 * When scheduling a cleanup task we overshoot the deadline by this many
+	 * milliseconds to reduce the number of tasks that need to be scheduled
+	 * when messages have cleanup deadlines that are close together.
+	 */
+	long BATCH_DELAY_MS = 1000;
+
+	/**
+	 * Registers a hook to be called when messages are due for cleanup.
+	 * This method should be called before
+	 * {@link LifecycleManager#startServices(SecretKey)}.
+	 */
+	void registerCleanupHook(ClientId c, int majorVersion,
+			CleanupHook hook);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/cleanup/event/CleanupTimerStartedEvent.java

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.api.cleanup.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a message's cleanup timer is started.
+ */
+@Immutable
+@NotNullByDefault
+public class CleanupTimerStartedEvent extends Event {
+
+	private final MessageId messageId;
+	private final long cleanupDeadline;
+
+	public CleanupTimerStartedEvent(MessageId messageId,
+			long cleanupDeadline) {
+		this.messageId = messageId;
+		this.cleanupDeadline = cleanupDeadline;
+	}
+
+	public MessageId getMessageId() {
+		return messageId;
+	}
+
+	public long getCleanupDeadline() {
+		return cleanupDeadline;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/client/ClientHelper.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.api.client;
 
 import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
@@ -16,6 +17,7 @@ import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 
 import java.security.GeneralSecurityException;
+import java.util.Collection;
 import java.util.Map;
 
 @NotNullByDefault
@@ -50,9 +52,11 @@ public interface ClientHelper {
 	BdfDictionary getGroupMetadataAsDictionary(Transaction txn, GroupId g)
 			throws DbException, FormatException;
 
+	Collection<MessageId> getMessageIds(Transaction txn, GroupId g,
+			BdfDictionary query) throws DbException, FormatException;
+
 	BdfDictionary getMessageMetadataAsDictionary(MessageId m)
-			throws DbException,
+			throws DbException, FormatException;
-			FormatException;
 
 	BdfDictionary getMessageMetadataAsDictionary(Transaction txn, MessageId m)
 			throws DbException, FormatException;
@@ -119,4 +123,17 @@ public interface ClientHelper {
 	Map<TransportId, TransportProperties> parseAndValidateTransportPropertiesMap(
 			BdfDictionary properties) throws FormatException;
 
+	/**
+	 * Retrieves the contact ID from the group metadata of the given contact
+	 * group.
+	 */
+	ContactId getContactId(Transaction txn, GroupId contactGroupId)
+			throws DbException, FormatException;
+
+	/**
+	 * Stores the given contact ID in the group metadata of the given contact
+	 * group.
+	 */
+	void setContactId(Transaction txn, GroupId contactGroupId, ContactId c)
+			throws DbException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/client/ContactGroupConstants.java

@@ -0,0 +1,9 @@
+package org.briarproject.bramble.api.client;
+
+public interface ContactGroupConstants {
+
+	/**
+	 * Group metadata key for associating a contact ID with a contact group.
+	 */
+	String GROUP_KEY_CONTACT_ID = "contactId";
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -41,6 +41,18 @@ import javax.annotation.Nullable;
 @NotNullByDefault
 public interface DatabaseComponent extends TransactionManager {
 
+	/**
+	 * Return value for {@link #getNextCleanupDeadline(Transaction)} if
+	 * no messages are scheduled to be deleted.
+	 */
+	long NO_CLEANUP_DEADLINE = -1;
+
+	/**
+	 * Return value for {@link #startCleanupTimer(Transaction, MessageId)}
+	 * if the cleanup timer was not started.
+	 */
+	long TIMER_NOT_STARTED = -1;
+
 	/**
 	 * Opens the database and returns true if the database already existed.
 	 *
@@ -288,6 +300,16 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<MessageId> getMessageIds(Transaction txn, GroupId g)
 			throws DbException;
 
+	/**
+	 * Returns the IDs of any delivered messages in the given group with
+	 * metadata that matches all entries in the given query. If the query is
+	 * empty, the IDs of all delivered messages are returned.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<MessageId> getMessageIds(Transaction txn, GroupId g,
+			Metadata query) throws DbException;
+
 	/**
 	 * Returns the IDs of any messages that need to be validated.
 	 * <p/>
@@ -314,6 +336,15 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<MessageId> getMessagesToShare(Transaction txn)
 			throws DbException;
 
+	/**
+	 * Returns the IDs of any messages of any messages that are due for
+	 * deletion, along with their group IDs.
+	 * <p/>
+	 * Read-only.
+	 */
+	Map<GroupId, Collection<MessageId>> getMessagesToDelete(Transaction txn)
+			throws DbException;
+
 	/**
 	 * Returns the metadata for all delivered messages in the given group.
 	 * <p/>
@@ -395,6 +426,15 @@ public interface DatabaseComponent extends TransactionManager {
 	MessageStatus getMessageStatus(Transaction txn, ContactId c, MessageId m)
 			throws DbException;
 
+	/**
+	 * Returns the next time (in milliseconds since the Unix epoch) when a
+	 * message is due to be deleted, or {@link #NO_CLEANUP_DEADLINE}
+	 * if no messages are scheduled to be deleted.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getNextCleanupDeadline(Transaction txn) throws DbException;
+
 	/*
 	 * Returns the next time (in milliseconds since the Unix epoch) when a
 	 * message is due to be sent to the given contact. The returned value may
@@ -535,6 +575,13 @@ public interface DatabaseComponent extends TransactionManager {
 	void removeTransportKeys(Transaction txn, TransportId t, KeySetId k)
 			throws DbException;
 
+	/**
+	 * Sets the cleanup timer duration for the given message. This does not
+	 * start the message's cleanup timer.
+	 */
+	void setCleanupTimerDuration(Transaction txn, MessageId m, long duration)
+			throws DbException;
+
 	/**
 	 * Marks the given contact as verified.
 	 */
@@ -557,6 +604,12 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	void setMessagePermanent(Transaction txn, MessageId m) throws DbException;
 
+	/**
+	 * Marks the given message as not shared. This method is only meant for
+	 * testing.
+	 */
+	void setMessageNotShared(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Marks the given message as shared.
 	 */
@@ -599,6 +652,22 @@ public interface DatabaseComponent extends TransactionManager {
 	void setTransportKeysActive(Transaction txn, TransportId t, KeySetId k)
 			throws DbException;
 
+	/**
+	 * Starts the cleanup timer for the given message, if a timer duration
+	 * has been set and the timer has not already been started.
+	 *
+	 * @return The cleanup deadline, or {@link #TIMER_NOT_STARTED} if no
+	 * timer duration has been set for this message or its timer has already
+	 * been started.
+	 */
+	long startCleanupTimer(Transaction txn, MessageId m) throws DbException;
+
+	/**
+	 * Stops the cleanup timer for the given message, if the timer has been
+	 * started.
+	 */
+	void stopCleanupTimer(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Stores the given transport keys, deleting any keys they have replaced.
 	 */

bramble-api/src/main/java/org/briarproject/bramble/util/ValidationUtils.java

@@ -6,7 +6,9 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
 
+@Immutable
 @NotNullByDefault
 public class ValidationUtils {
 
@@ -64,4 +66,9 @@ public class ValidationUtils {
 		if (dictionary != null && dictionary.size() != size)
 			throw new FormatException();
 	}
+
+	public static void checkRange(@Nullable Long l, long min, long max)
+			throws FormatException {
+		if (l != null && (l < min || l > max)) throw new FormatException();
+	}
 }

bramble-api/src/test/java/org/briarproject/bramble/test/TimeTravel.java

@@ -0,0 +1,8 @@
+package org.briarproject.bramble.test;
+
+public interface TimeTravel {
+
+	void setCurrentTimeMillis(long now) throws InterruptedException;
+
+	void addCurrentTimeMillis(long add) throws InterruptedException;
+}

bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreEagerSingletons.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble;
 
+import org.briarproject.bramble.cleanup.CleanupModule;
 import org.briarproject.bramble.contact.ContactModule;
 import org.briarproject.bramble.crypto.CryptoExecutorModule;
 import org.briarproject.bramble.db.DatabaseExecutorModule;
@@ -14,6 +15,8 @@ import org.briarproject.bramble.versioning.VersioningModule;
 
 public interface BrambleCoreEagerSingletons {
 
+	void inject(CleanupModule.EagerSingletons init);
+
 	void inject(ContactModule.EagerSingletons init);
 
 	void inject(CryptoExecutorModule.EagerSingletons init);
@@ -39,6 +42,7 @@ public interface BrambleCoreEagerSingletons {
 	class Helper {
 
 		public static void injectEagerSingletons(BrambleCoreEagerSingletons c) {
+			c.inject(new CleanupModule.EagerSingletons());
 			c.inject(new ContactModule.EagerSingletons());
 			c.inject(new CryptoExecutorModule.EagerSingletons());
 			c.inject(new DatabaseExecutorModule.EagerSingletons());

bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreModule.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble;
 
+import org.briarproject.bramble.cleanup.CleanupModule;
 import org.briarproject.bramble.client.ClientModule;
 import org.briarproject.bramble.connection.ConnectionModule;
 import org.briarproject.bramble.contact.ContactModule;
@@ -21,15 +22,14 @@ import org.briarproject.bramble.rendezvous.RendezvousModule;
 import org.briarproject.bramble.settings.SettingsModule;
 import org.briarproject.bramble.sync.SyncModule;
 import org.briarproject.bramble.sync.validation.ValidationModule;
-import org.briarproject.bramble.system.ClockModule;
 import org.briarproject.bramble.transport.TransportModule;
 import org.briarproject.bramble.versioning.VersioningModule;
 
 import dagger.Module;
 
 @Module(includes = {
+		CleanupModule.class,
 		ClientModule.class,
-		ClockModule.class,
 		ConnectionModule.class,
 		ContactModule.class,
 		CryptoModule.class,

bramble-core/src/main/java/org/briarproject/bramble/cleanup/CleanupManagerImpl.java

@@ -0,0 +1,159 @@
+package org.briarproject.bramble.cleanup;
+
+import org.briarproject.bramble.api.cleanup.CleanupHook;
+import org.briarproject.bramble.api.cleanup.CleanupManager;
+import org.briarproject.bramble.api.cleanup.event.CleanupTimerStartedEvent;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.lifecycle.Service;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.ClientId;
+import org.briarproject.bramble.api.sync.Group;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.system.TaskScheduler;
+import org.briarproject.bramble.api.versioning.ClientMajorVersion;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
+import javax.inject.Inject;
+
+import static java.lang.Math.max;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.db.DatabaseComponent.NO_CLEANUP_DEADLINE;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@ThreadSafe
+@NotNullByDefault
+class CleanupManagerImpl implements CleanupManager, Service, EventListener {
+
+	private static final Logger LOG =
+			getLogger(CleanupManagerImpl.class.getName());
+
+	private final Executor dbExecutor;
+	private final DatabaseComponent db;
+	private final TaskScheduler taskScheduler;
+	private final Clock clock;
+	private final Map<ClientMajorVersion, CleanupHook> hooks =
+			new ConcurrentHashMap<>();
+	private final Object lock = new Object();
+
+	@GuardedBy("lock")
+	private final Set<CleanupTask> pending = new HashSet<>();
+
+	@Inject
+	CleanupManagerImpl(@DatabaseExecutor Executor dbExecutor,
+			DatabaseComponent db, TaskScheduler taskScheduler, Clock clock) {
+		this.dbExecutor = dbExecutor;
+		this.db = db;
+		this.taskScheduler = taskScheduler;
+		this.clock = clock;
+	}
+
+	@Override
+	public void registerCleanupHook(ClientId c, int majorVersion,
+			CleanupHook hook) {
+		hooks.put(new ClientMajorVersion(c, majorVersion), hook);
+	}
+
+	@Override
+	public void startService() {
+		maybeScheduleTask(clock.currentTimeMillis());
+	}
+
+	@Override
+	public void stopService() {
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof CleanupTimerStartedEvent) {
+			CleanupTimerStartedEvent a = (CleanupTimerStartedEvent) e;
+			maybeScheduleTask(a.getCleanupDeadline());
+		}
+	}
+
+	private void maybeScheduleTask(long deadline) {
+		synchronized (lock) {
+			for (CleanupTask task : pending) {
+				if (task.deadline <= deadline) return;
+			}
+			CleanupTask task = new CleanupTask(deadline);
+			pending.add(task);
+			scheduleTask(task);
+		}
+	}
+
+	private void scheduleTask(CleanupTask task) {
+		long now = clock.currentTimeMillis();
+		long delay = max(0, task.deadline - now + BATCH_DELAY_MS);
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Scheduling cleanup task in " + delay + " ms");
+		}
+		taskScheduler.schedule(() -> deleteMessagesAndScheduleNextTask(task),
+				dbExecutor, delay, MILLISECONDS);
+	}
+
+	private void deleteMessagesAndScheduleNextTask(CleanupTask task) {
+		try {
+			synchronized (lock) {
+				pending.remove(task);
+			}
+			long deadline = db.transactionWithResult(false, txn -> {
+				deleteMessages(txn);
+				return db.getNextCleanupDeadline(txn);
+			});
+			if (deadline != NO_CLEANUP_DEADLINE) {
+				maybeScheduleTask(deadline);
+			}
+		} catch (DbException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
+
+	private void deleteMessages(Transaction txn) throws DbException {
+		Map<GroupId, Collection<MessageId>> ids = db.getMessagesToDelete(txn);
+		for (Entry<GroupId, Collection<MessageId>> e : ids.entrySet()) {
+			GroupId groupId = e.getKey();
+			Collection<MessageId> messageIds = e.getValue();
+			if (LOG.isLoggable(INFO)) {
+				LOG.info(messageIds.size() + " messages to delete");
+			}
+			for (MessageId m : messageIds) db.stopCleanupTimer(txn, m);
+			Group group = db.getGroup(txn, groupId);
+			ClientMajorVersion cv = new ClientMajorVersion(group.getClientId(),
+					group.getMajorVersion());
+			CleanupHook hook = hooks.get(cv);
+			if (hook == null) {
+				throw new IllegalStateException("No cleanup hook for " + cv);
+			}
+			hook.deleteMessages(txn, groupId, messageIds);
+		}
+	}
+
+	private static class CleanupTask {
+
+		private final long deadline;
+
+		private CleanupTask(long deadline) {
+			this.deadline = deadline;
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/cleanup/CleanupModule.java

@@ -0,0 +1,29 @@
+package org.briarproject.bramble.cleanup;
+
+import org.briarproject.bramble.api.cleanup.CleanupManager;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class CleanupModule {
+
+	public static class EagerSingletons {
+		@Inject
+		CleanupManager cleanupManager;
+	}
+
+	@Provides
+	@Singleton
+	CleanupManager provideCleanupManager(LifecycleManager lifecycleManager,
+			EventBus eventBus, CleanupManagerImpl cleanupManager) {
+		lifecycleManager.registerService(cleanupManager);
+		eventBus.addListener(cleanupManager);
+		return cleanupManager;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/client/ClientHelperImpl.java

@@ -2,11 +2,13 @@ package org.briarproject.bramble.client;
 
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.client.ClientHelper;
+import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyParser;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
+import org.briarproject.bramble.api.data.BdfEntry;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.data.BdfReader;
 import org.briarproject.bramble.api.data.BdfReaderFactory;
@@ -32,6 +34,7 @@ import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.security.GeneralSecurityException;
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -39,6 +42,7 @@ import java.util.Map.Entry;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.client.ContactGroupConstants.GROUP_KEY_CONTACT_ID;
 import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
@@ -151,6 +155,12 @@ class ClientHelperImpl implements ClientHelper {
 		return metadataParser.parse(metadata);
 	}
 
+	@Override
+	public Collection<MessageId> getMessageIds(Transaction txn, GroupId g,
+			BdfDictionary query) throws DbException, FormatException {
+		return db.getMessageIds(txn, g, metadataEncoder.encode(query));
+	}
+
 	@Override
 	public BdfDictionary getMessageMetadataAsDictionary(MessageId m)
 			throws DbException, FormatException {
@@ -389,4 +399,27 @@ class ClientHelperImpl implements ClientHelper {
 		return tpMap;
 	}
 
+	@Override
+	public ContactId getContactId(Transaction txn, GroupId contactGroupId)
+			throws DbException {
+		try {
+			BdfDictionary meta =
+					getGroupMetadataAsDictionary(txn, contactGroupId);
+			return new ContactId(meta.getLong(GROUP_KEY_CONTACT_ID).intValue());
+		} catch (FormatException e) {
+			throw new DbException(e); // Invalid group metadata
+		}
+	}
+
+	@Override
+	public void setContactId(Transaction txn, GroupId contactGroupId,
+			ContactId c) throws DbException {
+		BdfDictionary meta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_CONTACT_ID, c.getInt()));
+		try {
+			mergeGroupMetadata(txn, contactGroupId, meta);
+		} catch (FormatException e) {
+			throw new AssertionError(e);
+		}
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/db/Database.java

@@ -497,6 +497,25 @@ interface Database<T> {
 	 */
 	Collection<MessageId> getMessagesToShare(T txn) throws DbException;
 
+	/**
+	 * Returns the IDs of any messages of any messages that are due for
+	 * deletion, along with their group IDs.
+	 * <p/>
+	 * Read-only.
+	 */
+	Map<GroupId, Collection<MessageId>> getMessagesToDelete(T txn)
+			throws DbException;
+
+	/**
+	 * Returns the next time (in milliseconds since the Unix epoch) when a
+	 * message is due to be deleted, or
+	 * {@link DatabaseComponent#NO_CLEANUP_DEADLINE} if no messages are
+	 * scheduled to be deleted.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getNextCleanupDeadline(T txn) throws DbException;
+
 	/**
 	 * Returns the next time (in milliseconds since the Unix epoch) when a
 	 * message is due to be sent to the given contact. The returned value may
@@ -606,8 +625,10 @@ interface Database<T> {
 
 	/**
 	 * Marks a message as having been seen by the given contact.
+	 *
+	 * @return True if the message was not already marked as seen.
 	 */
-	void raiseSeenFlag(T txn, ContactId c, MessageId m) throws DbException;
+	boolean raiseSeenFlag(T txn, ContactId c, MessageId m) throws DbException;
 
 	/**
 	 * Removes a contact from the database.
@@ -671,6 +692,13 @@ interface Database<T> {
 	 */
 	void resetExpiryTime(T txn, ContactId c, MessageId m) throws DbException;
 
+	/**
+	 * Sets the cleanup timer duration for the given message. This does not
+	 * start the message's cleanup timer.
+	 */
+	void setCleanupTimerDuration(T txn, MessageId m, long duration)
+			throws DbException;
+
 	/**
 	 * Marks the given contact as verified.
 	 */
@@ -701,9 +729,10 @@ interface Database<T> {
 	void setMessagePermanent(T txn, MessageId m) throws DbException;
 
 	/**
-	 * Marks the given message as shared.
+	 * Marks the given message as shared or not.
 	 */
-	void setMessageShared(T txn, MessageId m) throws DbException;
+	void setMessageShared(T txn, MessageId m, boolean shared)
+			throws DbException;
 
 	/**
 	 * Sets the validation and delivery state of the given message.
@@ -730,6 +759,22 @@ interface Database<T> {
 	void setTransportKeysActive(T txn, TransportId t, KeySetId k)
 			throws DbException;
 
+	/**
+	 * Starts the cleanup timer for the given message, if a timer duration
+	 * has been set and the timer has not already been started.
+	 *
+	 * @return The cleanup deadline, or
+	 * {@link DatabaseComponent#TIMER_NOT_STARTED} if no timer duration has
+	 * been set for this message or its timer has already been started.
+	 */
+	long startCleanupTimer(T txn, MessageId m) throws DbException;
+
+	/**
+	 * Stops the cleanup timer for the given message, if the timer has been
+	 * started.
+	 */
+	void stopCleanupTimer(T txn, MessageId m) throws DbException;
+
 	/**
 	 * Updates the transmission count, expiry time and estimated time of arrival
 	 * of the given message with respect to the given contact, using the latency

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.db;
 
+import org.briarproject.bramble.api.cleanup.event.CleanupTimerStartedEvent;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.PendingContact;
@@ -576,6 +577,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessageIds(txn, g);
 	}
 
+	@Override
+	public Collection<MessageId> getMessageIds(Transaction transaction,
+			GroupId g, Metadata query) throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsGroup(txn, g))
+			throw new NoSuchGroupException();
+		return db.getMessageIds(txn, g, query);
+	}
+
 	@Override
 	public Collection<MessageId> getMessagesToValidate(Transaction transaction)
 			throws DbException {
@@ -597,6 +607,13 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessagesToShare(txn);
 	}
 
+	@Override
+	public Map<GroupId, Collection<MessageId>> getMessagesToDelete(
+			Transaction transaction) throws DbException {
+		T txn = unbox(transaction);
+		return db.getMessagesToDelete(txn);
+	}
+
 	@Override
 	public Map<MessageId, Metadata> getMessageMetadata(Transaction transaction,
 			GroupId g) throws DbException {
@@ -692,6 +709,13 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessageDependents(txn, m);
 	}
 
+	@Override
+	public long getNextCleanupDeadline(Transaction transaction)
+			throws DbException {
+		T txn = unbox(transaction);
+		return db.getNextCleanupDeadline(txn);
+	}
+
 	@Override
 	public long getNextSendTime(Transaction transaction, ContactId c)
 			throws DbException {
@@ -795,8 +819,17 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		Collection<MessageId> acked = new ArrayList<>();
 		for (MessageId m : a.getMessageIds()) {
 			if (db.containsVisibleMessage(txn, c, m)) {
-				db.raiseSeenFlag(txn, c, m);
+				if (db.raiseSeenFlag(txn, c, m)) {
-				acked.add(m);
+					// This is the first time the message has been acked by
+					// this contact. Start the cleanup timer (a no-op unless
+					// a cleanup deadline has been set for this message)
+					long deadline = db.startCleanupTimer(txn, m);
+					if (deadline != TIMER_NOT_STARTED) {
+						transaction.attach(new CleanupTimerStartedEvent(m,
+								deadline));
+					}
+					acked.add(m);
+				}
 			}
 		}
 		if (acked.size() > 0) {
@@ -952,6 +985,16 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.removeTransportKeys(txn, t, k);
 	}
 
+	@Override
+	public void setCleanupTimerDuration(Transaction transaction, MessageId m,
+			long duration) throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		db.setCleanupTimerDuration(txn, m, duration);
+	}
+
 	@Override
 	public void setContactVerified(Transaction transaction, ContactId c)
 			throws DbException {
@@ -1001,6 +1044,16 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.setMessagePermanent(txn, m);
 	}
 
+	@Override
+	public void setMessageNotShared(Transaction transaction, MessageId m)
+			throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		db.setMessageShared(txn, m, false);
+	}
+
 	@Override
 	public void setMessageShared(Transaction transaction, MessageId m)
 			throws DbException {
@@ -1010,7 +1063,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 			throw new NoSuchMessageException();
 		if (db.getMessageState(txn, m) != DELIVERED)
 			throw new IllegalArgumentException("Shared undelivered message");
-		db.setMessageShared(txn, m);
+		db.setMessageShared(txn, m, true);
 		transaction.attach(new MessageSharedEvent(m));
 	}
 
@@ -1082,6 +1135,30 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.setTransportKeysActive(txn, t, k);
 	}
 
+	@Override
+	public long startCleanupTimer(Transaction transaction, MessageId m)
+			throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		long deadline = db.startCleanupTimer(txn, m);
+		if (deadline != TIMER_NOT_STARTED) {
+			transaction.attach(new CleanupTimerStartedEvent(m, deadline));
+		}
+		return deadline;
+	}
+
+	@Override
+	public void stopCleanupTimer(Transaction transaction, MessageId m)
+			throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		db.stopCleanupTimer(txn, m);
+	}
+
 	@Override
 	public void updateTransportKeys(Transaction transaction,
 			Collection<TransportKeySet> keys) throws DbException {

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -72,6 +72,8 @@ import static java.util.Arrays.asList;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.db.DatabaseComponent.NO_CLEANUP_DEADLINE;
+import static org.briarproject.bramble.api.db.DatabaseComponent.TIMER_NOT_STARTED;
 import static org.briarproject.bramble.api.db.Metadata.REMOVE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
@@ -98,7 +100,7 @@ import static org.briarproject.bramble.util.LogUtils.now;
 abstract class JdbcDatabase implements Database<Connection> {
 
 	// Package access for testing
-	static final int CODE_SCHEMA_VERSION = 47;
+	static final int CODE_SCHEMA_VERSION = 48;
 
 	// Time period offsets for incoming transport keys
 	private static final int OFFSET_PREV = -1;
@@ -180,6 +182,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " state INT NOT NULL,"
 					+ " shared BOOLEAN NOT NULL,"
 					+ " temporary BOOLEAN NOT NULL,"
+					// Null if no timer duration has been set
+					+ " cleanupTimerDuration BIGINT,"
+					// Null if no timer duration has been set or the timer
+					// hasn't started
+					+ " cleanupDeadline BIGINT,"
 					+ " length INT NOT NULL,"
 					+ " raw BLOB," // Null if message has been deleted
 					+ " PRIMARY KEY (messageId),"
@@ -336,6 +343,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 			"CREATE INDEX IF NOT EXISTS statusesByContactIdTimestamp"
 					+ " ON statuses (contactId, timestamp)";
 
+	private static final String INDEX_MESSAGES_BY_CLEANUP_DEADLINE =
+			"CREATE INDEX IF NOT EXISTS messagesByCleanupDeadline"
+					+ " ON messages (cleanupDeadline)";
+
 	private static final Logger LOG =
 			getLogger(JdbcDatabase.class.getName());
 
@@ -463,7 +474,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 				new Migration43_44(dbTypes),
 				new Migration44_45(),
 				new Migration45_46(),
-				new Migration46_47(dbTypes)
+				new Migration46_47(dbTypes),
+				new Migration47_48()
 		);
 	}
 
@@ -531,6 +543,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			s.executeUpdate(INDEX_MESSAGE_DEPENDENCIES_BY_DEPENDENCY_ID);
 			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_GROUP_ID);
 			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_TIMESTAMP);
+			s.executeUpdate(INDEX_MESSAGES_BY_CLEANUP_DEADLINE);
 			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
@@ -1290,7 +1303,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 	public void deleteMessage(Connection txn, MessageId m) throws DbException {
 		PreparedStatement ps = null;
 		try {
-			String sql = "UPDATE messages SET raw = NULL WHERE messageId = ?";
+			String sql = "UPDATE messages"
+					+ " SET raw = NULL, cleanupDeadline = NULL"
+					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			int affected = ps.executeUpdate();
@@ -1769,7 +1784,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 				// Return early if there are no matches
 				if (intersection.isEmpty()) return Collections.emptySet();
 			}
-			if (intersection == null) throw new AssertionError();
 			return intersection;
 		} catch (SQLException e) {
 			tryToClose(rs, LOG, WARNING);
@@ -2226,6 +2240,39 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public Map<GroupId, Collection<MessageId>> getMessagesToDelete(
+			Connection txn) throws DbException {
+		long now = clock.currentTimeMillis();
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT messageId, groupId FROM messages"
+					+ " WHERE cleanupDeadline <= ?";
+			ps = txn.prepareStatement(sql);
+			ps.setLong(1, now);
+			rs = ps.executeQuery();
+			Map<GroupId, Collection<MessageId>> ids = new HashMap<>();
+			while (rs.next()) {
+				MessageId m = new MessageId(rs.getBytes(1));
+				GroupId g = new GroupId(rs.getBytes(2));
+				Collection<MessageId> messageIds = ids.get(g);
+				if (messageIds == null) {
+					messageIds = new ArrayList<>();
+					ids.put(g, messageIds);
+				}
+				messageIds.add(m);
+			}
+			rs.close();
+			ps.close();
+			return ids;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public long getNextSendTime(Connection txn, ContactId c)
 			throws DbException {
@@ -2256,6 +2303,31 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public long getNextCleanupDeadline(Connection txn) throws DbException {
+		Statement s = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT cleanupDeadline FROM messages"
+					+ " WHERE cleanupDeadline IS NOT NULL"
+					+ " ORDER BY cleanupDeadline LIMIT 1";
+			s = txn.createStatement();
+			rs = s.executeQuery(sql);
+			long nextDeadline = NO_CLEANUP_DEADLINE;
+			if (rs.next()) {
+				nextDeadline = rs.getLong(1);
+				if (rs.next()) throw new AssertionError();
+			}
+			rs.close();
+			s.close();
+			return nextDeadline;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public PendingContact getPendingContact(Connection txn, PendingContactId p)
 			throws DbException {
@@ -2776,7 +2848,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void raiseSeenFlag(Connection txn, ContactId c, MessageId m)
+	public boolean raiseSeenFlag(Connection txn, ContactId c, MessageId m)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {
@@ -2788,6 +2860,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
+			return affected == 1;
 		} catch (SQLException e) {
 			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
@@ -3021,6 +3094,25 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public void setCleanupTimerDuration(Connection txn, MessageId m,
+			long duration) throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "UPDATE messages SET cleanupTimerDuration = ?"
+					+ " WHERE messageId = ? AND cleanupTimerDuration IS NULL";
+			ps = txn.prepareStatement(sql);
+			ps.setLong(1, duration);
+			ps.setBytes(2, m.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void setContactVerified(Connection txn, ContactId c)
 			throws DbException {
@@ -3128,22 +3220,24 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void setMessageShared(Connection txn, MessageId m)
+	public void setMessageShared(Connection txn, MessageId m, boolean shared)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {
-			String sql = "UPDATE messages SET shared = TRUE"
+			String sql = "UPDATE messages SET shared = ?"
 					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
-			ps.setBytes(1, m.getBytes());
+			ps.setBoolean(1, shared);
+			ps.setBytes(2, m.getBytes());
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 			// Update denormalised column in statuses
-			sql = "UPDATE statuses SET messageShared = TRUE"
+			sql = "UPDATE statuses SET messageShared = ?"
 					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
-			ps.setBytes(1, m.getBytes());
+			ps.setBoolean(1, shared);
+			ps.setBytes(2, m.getBytes());
 			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
 			ps.close();
@@ -3272,6 +3366,60 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public long startCleanupTimer(Connection txn, MessageId m)
+			throws DbException {
+		long now = clock.currentTimeMillis();
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "UPDATE messages"
+					+ " SET cleanupDeadline = ? + cleanupTimerDuration"
+					+ " WHERE messageId = ?"
+					+ " AND cleanupTimerDuration IS NOT NULL"
+					+ " AND cleanupDeadline IS NULL";
+			ps = txn.prepareStatement(sql);
+			ps.setLong(1, now);
+			ps.setBytes(2, m.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+			if (affected == 0) return TIMER_NOT_STARTED;
+			sql = "SELECT cleanupDeadline FROM messages WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			long deadline = rs.getLong(1);
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			return deadline;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
+	@Override
+	public void stopCleanupTimer(Connection txn, MessageId m)
+			throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "UPDATE messages SET cleanupDeadline = NULL"
+					+ " WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void updateExpiryTimeAndEta(Connection txn, ContactId c, MessageId m,
 			int maxLatency) throws DbException {

bramble-core/src/main/java/org/briarproject/bramble/db/Migration47_48.java

@@ -0,0 +1,47 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DbException;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Logger;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+
+class Migration47_48 implements Migration<Connection> {
+
+	private static final Logger LOG = getLogger(Migration47_48.class.getName());
+
+	@Override
+	public int getStartVersion() {
+		return 47;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 48;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			s = txn.createStatement();
+			// Null if no timer duration has been set
+			s.execute("ALTER TABLE messages"
+					+ " ADD COLUMN cleanupTimerDuration BIGINT");
+			// Null if no timer duration has been set or the timer
+			// hasn't started
+			s.execute("ALTER TABLE messages"
+					+ " ADD COLUMN cleanupDeadline BIGINT");
+			s.execute("CREATE INDEX IF NOT EXISTS messagesByCleanupDeadline"
+					+ " ON messages (cleanupDeadline)");
+		} catch (SQLException e) {
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/versioning/ClientVersioningConstants.java

@@ -5,6 +5,5 @@ interface ClientVersioningConstants {
 	// Metadata keys
 	String MSG_KEY_UPDATE_VERSION = "version";
 	String MSG_KEY_LOCAL = "local";
-	String GROUP_KEY_CONTACT_ID = "contactId";
 }
 

bramble-core/src/main/java/org/briarproject/bramble/versioning/ClientVersioningManagerImpl.java

@@ -50,7 +50,6 @@ import static java.util.Collections.emptyList;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
 import static org.briarproject.bramble.api.sync.Group.Visibility.VISIBLE;
-import static org.briarproject.bramble.versioning.ClientVersioningConstants.GROUP_KEY_CONTACT_ID;
 import static org.briarproject.bramble.versioning.ClientVersioningConstants.MSG_KEY_LOCAL;
 import static org.briarproject.bramble.versioning.ClientVersioningConstants.MSG_KEY_UPDATE_VERSION;
 
@@ -161,13 +160,7 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 		db.addGroup(txn, g);
 		db.setGroupVisibility(txn, c.getId(), g.getId(), SHARED);
 		// Attach the contact ID to the group
-		BdfDictionary meta = new BdfDictionary();
+		clientHelper.setContactId(txn, g.getId(), c.getId());
-		meta.put(GROUP_KEY_CONTACT_ID, c.getId().getInt());
-		try {
-			clientHelper.mergeGroupMetadata(txn, g.getId(), meta);
-		} catch (FormatException e) {
-			throw new AssertionError(e);
-		}
 		// Create and store the first local update
 		List<ClientVersion> versions = new ArrayList<>(clients);
 		Collections.sort(versions);
@@ -229,7 +222,7 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 			Map<ClientMajorVersion, Visibility> after =
 					getVisibilities(newLocalStates, newRemoteStates);
 			// Call hooks for any visibilities that have changed
-			ContactId c = getContactId(txn, m.getGroupId());
+			ContactId c = clientHelper.getContactId(txn, m.getGroupId());
 			if (!before.equals(after)) {
 				Contact contact = db.getContact(txn, c);
 				callVisibilityHooks(txn, contact, before, after);
@@ -521,17 +514,6 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 		storeUpdate(txn, g, states, 1);
 	}
 
-	private ContactId getContactId(Transaction txn, GroupId g)
-			throws DbException {
-		try {
-			BdfDictionary meta =
-					clientHelper.getGroupMetadataAsDictionary(txn, g);
-			return new ContactId(meta.getLong(GROUP_KEY_CONTACT_ID).intValue());
-		} catch (FormatException e) {
-			throw new DbException(e);
-		}
-	}
-
 	private List<ClientState> updateStatesFromRemoteStates(
 			List<ClientState> oldLocalStates, List<ClientState> remoteStates) {
 		Set<ClientMajorVersion> remoteSet = new HashSet<>();

bramble-core/src/main/resources/bridges

@@ -1,12 +1,13 @@
 Bridge obfs4 192.95.36.142:443 CDF2E852BF539B82BD10E27E9115A31734E378C2 cert=qUVQ0srL1JI/vO6V6m/24anYXiJD3QP2HgzUKQtQ7GRqqUvs7P+tG43RtAqdhLOALP7DJQ iat-mode=1
 Bridge obfs4 38.229.1.78:80 C8CBDB2464FC9804A69531437BCF2BE31FDD2EE4 cert=Hmyfd2ev46gGY7NoVxA9ngrPF2zCZtzskRTzoWXbxNkzeVnGFPWmrTtILRyqCTjHR+s9dg iat-mode=1
-Bridge obfs4 38.229.33.83:80 0BAC39417268B96B9F514E7F63FA6FBA1A788955 cert=VwEFpk9F/UN9JED7XpG1XOjm/O8ZCXK80oPecgWnNDZDv5pdkhq1OpbAH0wNqOT6H6BmRQ iat-mode=1
 Bridge obfs4 37.218.245.14:38224 D9A82D2F9C2F65A18407B1D2B764F130847F8B5D cert=bjRaMrr1BRiAW8IE9U5z27fQaYgOhX1UCmOpg2pFpoMvo6ZgQMzLsaTzzQNTlm7hNcb+Sg iat-mode=0
+Bridge obfs4 85.31.186.98:443 011F2599C0E9B27EE74B353155E244813763C3E5 cert=ayq0XzCwhpdysn5o0EyDUbmSOx3X/oTEbzDMvczHOdBJKlvIdHHLJGkZARtT4dcBFArPPg iat-mode=0
 Bridge obfs4 85.31.186.26:443 91A6354697E6B02A386312F68D82CF86824D3606 cert=PBwr+S8JTVZo6MPdHnkTwXJPILWADLqfMGoVvhZClMq/Urndyd42BwX9YFJHZnBB3H0XCw iat-mode=0
 Bridge obfs4 193.11.166.194:27015 2D82C2E354D531A68469ADF7F878FA6060C6BACA cert=4TLQPJrTSaDffMK7Nbao6LC7G9OW/NHkUwIdjLSS3KYf0Nv4/nQiiI8dY2TcsQx01NniOg iat-mode=0
 Bridge obfs4 193.11.166.194:27020 86AC7B8D430DAC4117E9F42C9EAED18133863AAF cert=0LDeJH4JzMDtkJJrFphJCiPqKx7loozKN7VNfuukMGfHO0Z8OGdzHVkhVAOfo1mUdv9cMg iat-mode=0
 Bridge obfs4 193.11.166.194:27025 1AE2C08904527FEA90C4C4F8C1083EA59FBC6FAF cert=ItvYZzW5tn6v3G4UnQa6Qz04Npro6e81AP70YujmK/KXwDFPTs3aHXcHp4n8Vt6w/bv8cA iat-mode=0
 Bridge obfs4 209.148.46.65:443 74FAD13168806246602538555B5521A0383A1875 cert=ssH+9rP8dG2NLDN2XuFw63hIO/9MNNinLmxQDpVa+7kTOa9/m+tGWT1SmSYpQ9uTBGa6Hw iat-mode=0
+Bridge obfs4 146.57.248.225:22 10A6CD36A537FCE513A322361547444B393989F0 cert=K1gDtDAIcUfeLqbstggjIw2rtgIKqdIhUlHp82XRqNSq/mtAjp1BIC9vHKJ2FAEpGssTPw iat-mode=0
 Bridge obfs4 45.145.95.6:27015 C5B7CD6946FF10C5B3E89691A7D3F2C122D2117C cert=TD7PbUO0/0k6xYHMPW3vJxICfkMZNdkRrb63Zhl5j9dW3iRGiCx0A7mPhe5T2EDzQ35+Zw iat-mode=0
 Bridge obfs4 51.222.13.177:80 5EDAC3B810E12B01F6FD8050D2FD3E277B289A08 cert=2uplIpLQ0q9+0qMFrK5pkaYRDOe460LL9WHBvatgkuRr/SL31wBOEupaMMJ6koRE6Ld0ew iat-mode=0
 Bridge obfs4 78.46.188.239:37356 5A2D2F4158D0453E00C7C176978D3F41D69C45DB cert=3c0SwxpOisbohNxEc4tb875RVW8eOu1opRTVXJhafaKA/PNNtI7ElQIVOVZg1AdL5bxGCw iat-mode=0

bramble-core/src/test/java/org/briarproject/bramble/BrambleCoreIntegrationTestEagerSingletons.java

@@ -1,18 +1,18 @@
 package org.briarproject.bramble;
 
-import org.briarproject.bramble.system.DefaultTaskSchedulerModule;
+import org.briarproject.bramble.system.TimeTravelModule;
 
 public interface BrambleCoreIntegrationTestEagerSingletons
 		extends BrambleCoreEagerSingletons {
 
-	void inject(DefaultTaskSchedulerModule.EagerSingletons init);
+	void inject(TimeTravelModule.EagerSingletons init);
 
 	class Helper {
 
 		public static void injectEagerSingletons(
 				BrambleCoreIntegrationTestEagerSingletons c) {
 			BrambleCoreEagerSingletons.Helper.injectEagerSingletons(c);
-			c.inject(new DefaultTaskSchedulerModule.EagerSingletons());
+			c.inject(new TimeTravelModule.EagerSingletons());
 		}
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/db/DatabaseComponentImplTest.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.db;
 
+import org.briarproject.bramble.api.cleanup.event.CleanupTimerStartedEvent;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.PendingContactId;
@@ -69,6 +70,8 @@ import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonList;
+import static java.util.concurrent.TimeUnit.HOURS;
+import static org.briarproject.bramble.api.db.DatabaseComponent.TIMER_NOT_STARTED;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
 import static org.briarproject.bramble.api.sync.Group.Visibility.VISIBLE;
@@ -510,11 +513,11 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			throws Exception {
 		context.checking(new Expectations() {{
 			// Check whether the group is in the DB (which it's not)
-			exactly(8).of(database).startTransaction();
+			exactly(10).of(database).startTransaction();
 			will(returnValue(txn));
-			exactly(8).of(database).containsGroup(txn, groupId);
+			exactly(10).of(database).containsGroup(txn, groupId);
 			will(returnValue(false));
-			exactly(8).of(database).abortTransaction(txn);
+			exactly(10).of(database).abortTransaction(txn);
 			// Allow other checks to pass
 			allowing(database).containsContact(txn, contactId);
 			will(returnValue(true));
@@ -523,7 +526,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 				eventExecutor, shutdownManager);
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getGroup(transaction, groupId));
 			fail();
 		} catch (NoSuchGroupException expected) {
@@ -531,7 +534,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getGroupMetadata(transaction, groupId));
 			fail();
 		} catch (NoSuchGroupException expected) {
@@ -539,7 +542,23 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
+					db.getMessageIds(transaction, groupId));
+			fail();
+		} catch (NoSuchGroupException expected) {
+			// Expected
+		}
+
+		try {
+			db.transaction(true, transaction ->
+					db.getMessageIds(transaction, groupId, new Metadata()));
+			fail();
+		} catch (NoSuchGroupException expected) {
+			// Expected
+		}
+
+		try {
+			db.transaction(true, transaction ->
 					db.getMessageMetadata(transaction, groupId));
 			fail();
 		} catch (NoSuchGroupException expected) {
@@ -547,7 +566,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getMessageMetadata(transaction, groupId,
 							new Metadata()));
 			fail();
@@ -556,7 +575,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getMessageStatus(transaction, contactId, groupId));
 			fail();
 		} catch (NoSuchGroupException expected) {
@@ -594,11 +613,11 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			throws Exception {
 		context.checking(new Expectations() {{
 			// Check whether the message is in the DB (which it's not)
-			exactly(12).of(database).startTransaction();
+			exactly(15).of(database).startTransaction();
 			will(returnValue(txn));
-			exactly(12).of(database).containsMessage(txn, messageId);
+			exactly(15).of(database).containsMessage(txn, messageId);
 			will(returnValue(false));
-			exactly(12).of(database).abortTransaction(txn);
+			exactly(15).of(database).abortTransaction(txn);
 			// Allow other checks to pass
 			allowing(database).containsContact(txn, contactId);
 			will(returnValue(true));
@@ -623,7 +642,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getMessage(transaction, messageId));
 			fail();
 		} catch (NoSuchMessageException expected) {
@@ -631,7 +650,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getMessageMetadata(transaction, messageId));
 			fail();
 		} catch (NoSuchMessageException expected) {
@@ -639,7 +658,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getMessageState(transaction, messageId));
 			fail();
 		} catch (NoSuchMessageException expected) {
@@ -647,7 +666,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getMessageStatus(transaction, contactId, messageId));
 			fail();
 		} catch (NoSuchMessageException expected) {
@@ -662,6 +681,15 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			// Expected
 		}
 
+		try {
+			db.transaction(false, transaction ->
+					db.setCleanupTimerDuration(transaction, message.getId(),
+							HOURS.toMillis(1)));
+			fail();
+		} catch (NoSuchMessageException expected) {
+			// Expected
+		}
+
 		try {
 			db.transaction(false, transaction ->
 					db.setMessagePermanent(transaction, message.getId()));
@@ -687,7 +715,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getMessageDependencies(transaction, messageId));
 			fail();
 		} catch (NoSuchMessageException expected) {
@@ -695,12 +723,28 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		}
 
 		try {
-			db.transaction(false, transaction ->
+			db.transaction(true, transaction ->
 					db.getMessageDependents(transaction, messageId));
 			fail();
 		} catch (NoSuchMessageException expected) {
 			// Expected
 		}
+
+		try {
+			db.transaction(false, transaction ->
+					db.startCleanupTimer(transaction, messageId));
+			fail();
+		} catch (NoSuchMessageException expected) {
+			// Expected
+		}
+
+		try {
+			db.transaction(false, transaction ->
+					db.stopCleanupTimer(transaction, messageId));
+			fail();
+		} catch (NoSuchMessageException expected) {
+			// Expected
+		}
 	}
 
 	@Test
@@ -981,6 +1025,9 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			oneOf(database).containsVisibleMessage(txn, contactId, messageId);
 			will(returnValue(true));
 			oneOf(database).raiseSeenFlag(txn, contactId, messageId);
+			will(returnValue(true));
+			oneOf(database).startCleanupTimer(txn, messageId);
+			will(returnValue(TIMER_NOT_STARTED)); // No cleanup duration was set
 			oneOf(database).commitTransaction(txn);
 			oneOf(eventBus).broadcast(with(any(MessagesAckedEvent.class)));
 		}});
@@ -993,6 +1040,56 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		});
 	}
 
+	@Test
+	public void testReceiveDuplicateAck() throws Exception {
+		context.checking(new Expectations() {{
+			oneOf(database).startTransaction();
+			will(returnValue(txn));
+			oneOf(database).containsContact(txn, contactId);
+			will(returnValue(true));
+			oneOf(database).containsVisibleMessage(txn, contactId, messageId);
+			will(returnValue(true));
+			oneOf(database).raiseSeenFlag(txn, contactId, messageId);
+			will(returnValue(false)); // Already acked
+			oneOf(database).commitTransaction(txn);
+		}});
+		DatabaseComponent db = createDatabaseComponent(database, eventBus,
+				eventExecutor, shutdownManager);
+
+		db.transaction(false, transaction -> {
+			Ack a = new Ack(singletonList(messageId));
+			db.receiveAck(transaction, contactId, a);
+		});
+	}
+
+	@Test
+	public void testReceiveAckWithCleanupTimer() throws Exception {
+		long deadline = System.currentTimeMillis();
+		context.checking(new Expectations() {{
+			oneOf(database).startTransaction();
+			will(returnValue(txn));
+			oneOf(database).containsContact(txn, contactId);
+			will(returnValue(true));
+			oneOf(database).containsVisibleMessage(txn, contactId, messageId);
+			will(returnValue(true));
+			oneOf(database).raiseSeenFlag(txn, contactId, messageId);
+			will(returnValue(true));
+			oneOf(database).startCleanupTimer(txn, messageId);
+			will(returnValue(deadline));
+			oneOf(database).commitTransaction(txn);
+			oneOf(eventBus).broadcast(with(any(
+					CleanupTimerStartedEvent.class)));
+			oneOf(eventBus).broadcast(with(any(MessagesAckedEvent.class)));
+		}});
+		DatabaseComponent db = createDatabaseComponent(database, eventBus,
+				eventExecutor, shutdownManager);
+
+		db.transaction(false, transaction -> {
+			Ack a = new Ack(singletonList(messageId));
+			db.receiveAck(transaction, contactId, a);
+		});
+	}
+
 	@Test
 	public void testReceiveMessage() throws Exception {
 		context.checking(new Expectations() {{

bramble-core/src/test/java/org/briarproject/bramble/db/JdbcDatabaseTest.java

@@ -53,10 +53,11 @@ import java.util.concurrent.atomic.AtomicLong;
 
 import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
-import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.singletonMap;
 import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.briarproject.bramble.api.db.DatabaseComponent.NO_CLEANUP_DEADLINE;
+import static org.briarproject.bramble.api.db.DatabaseComponent.TIMER_NOT_STARTED;
 import static org.briarproject.bramble.api.db.Metadata.REMOVE;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
@@ -351,7 +352,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertTrue(ids.isEmpty());
 
 		// Sharing the message should make it sendable
-		db.setMessageShared(txn, messageId);
+		db.setMessageShared(txn, messageId, true);
 		ids = db.getMessagesToSend(txn, contactId, ONE_MEGABYTE, MAX_LATENCY);
 		assertEquals(singletonList(messageId), ids);
 		ids = db.getMessagesToOffer(txn, contactId, 100, MAX_LATENCY);
@@ -631,8 +632,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// The group should not be visible to the contact
 		assertEquals(INVISIBLE, db.getGroupVisibility(txn, contactId, groupId));
-		assertEquals(emptyMap(),
+		assertTrue(db.getGroupVisibility(txn, groupId).isEmpty());
-				db.getGroupVisibility(txn, groupId));
 
 		// Make the group visible to the contact
 		db.addGroupVisibility(txn, contactId, groupId, false);
@@ -655,8 +655,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		// Make the group invisible again
 		db.removeGroupVisibility(txn, contactId, groupId);
 		assertEquals(INVISIBLE, db.getGroupVisibility(txn, contactId, groupId));
-		assertEquals(emptyMap(),
+		assertTrue(db.getGroupVisibility(txn, groupId).isEmpty());
-				db.getGroupVisibility(txn, groupId));
 
 		db.commitTransaction(txn);
 		db.close();
@@ -2040,7 +2039,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
 
 		// Share the message - now it should be sendable immediately
-		db.setMessageShared(txn, messageId);
+		db.setMessageShared(txn, messageId, true);
 		assertEquals(0, db.getNextSendTime(txn, contactId));
 
 		// Mark the message as requested - it should still be sendable
@@ -2347,6 +2346,87 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		db.close();
 	}
 
+	@Test
+	public void testCleanupTimer() throws Exception {
+		long duration = 60_000;
+		long now = System.currentTimeMillis();
+		AtomicLong time = new AtomicLong(now);
+		Database<Connection> db =
+				open(false, new TestMessageFactory(), new SettableClock(time));
+		Connection txn = db.startTransaction();
+
+		// No messages should be due or scheduled for deletion
+		assertTrue(db.getMessagesToDelete(txn).isEmpty());
+		assertEquals(NO_CLEANUP_DEADLINE, db.getNextCleanupDeadline(txn));
+
+		// Add a group and a message
+		db.addGroup(txn, group);
+		db.addMessage(txn, message, DELIVERED, false, false, null);
+
+		// No messages should be due or scheduled for deletion
+		assertTrue(db.getMessagesToDelete(txn).isEmpty());
+		assertEquals(NO_CLEANUP_DEADLINE, db.getNextCleanupDeadline(txn));
+
+		// Set the message's cleanup timer duration
+		db.setCleanupTimerDuration(txn, messageId, duration);
+
+		// No messages should be due or scheduled for deletion
+		assertTrue(db.getMessagesToDelete(txn).isEmpty());
+		assertEquals(NO_CLEANUP_DEADLINE, db.getNextCleanupDeadline(txn));
+
+		// Start the message's cleanup timer
+		assertEquals(now + duration, db.startCleanupTimer(txn, messageId));
+
+		// The timer can't be started again
+		assertEquals(TIMER_NOT_STARTED, db.startCleanupTimer(txn, messageId));
+
+		// No messages should be due for deletion, but the message should be
+		// scheduled for deletion
+		assertTrue(db.getMessagesToDelete(txn).isEmpty());
+		assertEquals(now + duration, db.getNextCleanupDeadline(txn));
+
+		// Stop the timer
+		db.stopCleanupTimer(txn, messageId);
+
+		// No messages should be due or scheduled for deletion
+		assertTrue(db.getMessagesToDelete(txn).isEmpty());
+		assertEquals(NO_CLEANUP_DEADLINE, db.getNextCleanupDeadline(txn));
+
+		// Start the timer again
+		assertEquals(now + duration, db.startCleanupTimer(txn, messageId));
+
+		// No messages should be due for deletion, but the message should be
+		// scheduled for deletion
+		assertTrue(db.getMessagesToDelete(txn).isEmpty());
+		assertEquals(now + duration, db.getNextCleanupDeadline(txn));
+
+		// 1 ms before the timer expires, no messages should be due for
+		// deletion but the message should be scheduled for deletion
+		time.set(now + duration - 1);
+		assertTrue(db.getMessagesToDelete(txn).isEmpty());
+		assertEquals(now + duration, db.getNextCleanupDeadline(txn));
+
+		// When the timer expires, the message should be due and scheduled for
+		// deletion
+		time.set(now + duration);
+		assertEquals(singletonMap(groupId, singletonList(messageId)),
+				db.getMessagesToDelete(txn));
+		assertEquals(now + duration, db.getNextCleanupDeadline(txn));
+
+		// 1 ms after the timer expires, the message should be due and
+		// scheduled for deletion
+		time.set(now + duration + 1);
+		assertEquals(singletonMap(groupId, singletonList(messageId)),
+				db.getMessagesToDelete(txn));
+		assertEquals(now + duration, db.getNextCleanupDeadline(txn));
+
+		// Once the message has been deleted, it should no longer be due
+		// or scheduled for deletion
+		db.deleteMessage(txn, messageId);
+		assertTrue(db.getMessagesToDelete(txn).isEmpty());
+		assertEquals(NO_CLEANUP_DEADLINE, db.getNextCleanupDeadline(txn));
+	}
+
 	private Database<Connection> open(boolean resume) throws Exception {
 		return open(resume, new TestMessageFactory(), new SystemClock());
 	}

bramble-core/src/test/java/org/briarproject/bramble/system/TestTaskScheduler.java

@@ -0,0 +1,122 @@
+package org.briarproject.bramble.system;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.system.TaskScheduler;
+
+import java.util.Queue;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executor;
+import java.util.concurrent.PriorityBlockingQueue;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static org.junit.Assert.fail;
+
+/**
+ * A {@link TaskScheduler} for use in tests. The scheduler keeps all scheduled
+ * tasks in a queue until {@link #runTasks()} is called.
+ */
+@NotNullByDefault
+class TestTaskScheduler implements TaskScheduler {
+
+	private final Queue<Task> queue = new PriorityBlockingQueue<>();
+	private final Clock clock;
+
+	TestTaskScheduler(Clock clock) {
+		this.clock = clock;
+	}
+
+	@Override
+	public Cancellable schedule(Runnable task, Executor executor, long delay,
+			TimeUnit unit) {
+		AtomicBoolean cancelled = new AtomicBoolean(false);
+		return schedule(task, executor, delay, unit, cancelled);
+	}
+
+	@Override
+	public Cancellable scheduleWithFixedDelay(Runnable task, Executor executor,
+			long delay, long interval, TimeUnit unit) {
+		AtomicBoolean cancelled = new AtomicBoolean(false);
+		return scheduleWithFixedDelay(task, executor, delay, interval, unit,
+				cancelled);
+	}
+
+	private Cancellable schedule(Runnable task, Executor executor, long delay,
+			TimeUnit unit, AtomicBoolean cancelled) {
+		long delayMillis = MILLISECONDS.convert(delay, unit);
+		long dueMillis = clock.currentTimeMillis() + delayMillis;
+		Task t = new Task(task, executor, dueMillis, cancelled);
+		queue.add(t);
+		return t;
+	}
+
+	private Cancellable scheduleWithFixedDelay(Runnable task, Executor executor,
+			long delay, long interval, TimeUnit unit, AtomicBoolean cancelled) {
+		// All executions of this periodic task share a cancelled flag
+		Runnable wrapped = () -> {
+			task.run();
+			scheduleWithFixedDelay(task, executor, interval, interval, unit,
+					cancelled);
+		};
+		return schedule(wrapped, executor, delay, unit, cancelled);
+	}
+
+	/**
+	 * Runs any scheduled tasks that are due.
+	 */
+	void runTasks() throws InterruptedException {
+		long now = clock.currentTimeMillis();
+		while (true) {
+			Task t = queue.peek();
+			if (t == null || t.dueMillis > now) return;
+			t = queue.poll();
+			// Submit the task to its executor and wait for it to finish
+			if (!t.run().await(1, MINUTES)) fail();
+		}
+	}
+
+	private static class Task
+			implements Cancellable, Comparable<Task> {
+
+		private final Runnable task;
+		private final Executor executor;
+		private final long dueMillis;
+		private final AtomicBoolean cancelled;
+
+		private Task(Runnable task, Executor executor, long dueMillis,
+				AtomicBoolean cancelled) {
+			this.task = task;
+			this.executor = executor;
+			this.dueMillis = dueMillis;
+			this.cancelled = cancelled;
+		}
+
+		@SuppressWarnings("UseCompareMethod") // Animal Sniffer
+		@Override
+		public int compareTo(Task task) {
+			return Long.valueOf(dueMillis).compareTo(task.dueMillis);
+		}
+
+		/**
+		 * Submits the task to its executor and returns a latch that will be
+		 * released when the task finishes.
+		 */
+		public CountDownLatch run() {
+			if (cancelled.get()) return new CountDownLatch(0);
+			CountDownLatch latch = new CountDownLatch(1);
+			executor.execute(() -> {
+				task.run();
+				latch.countDown();
+			});
+			return latch;
+		}
+
+		@Override
+		public void cancel() {
+			cancelled.set(true);
+		}
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/system/TimeTravelModule.java

@@ -0,0 +1,98 @@
+package org.briarproject.bramble.system;
+
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.system.TaskScheduler;
+import org.briarproject.bramble.test.SettableClock;
+import org.briarproject.bramble.test.TimeTravel;
+
+import java.util.concurrent.RejectedExecutionHandler;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
+import java.util.concurrent.atomic.AtomicLong;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class TimeTravelModule {
+
+	public static class EagerSingletons {
+		@Inject
+		TaskScheduler scheduler;
+	}
+
+	private final ScheduledExecutorService scheduledExecutorService;
+	private final Clock clock;
+	private final TaskScheduler taskScheduler;
+	private final TimeTravel timeTravel;
+
+	public TimeTravelModule() {
+		this(false);
+	}
+
+	public TimeTravelModule(boolean travel) {
+		// Discard tasks that are submitted during shutdown
+		RejectedExecutionHandler policy =
+				new ScheduledThreadPoolExecutor.DiscardPolicy();
+		scheduledExecutorService =
+				new ScheduledThreadPoolExecutor(1, policy);
+		if (travel) {
+			// Use a SettableClock and TestTaskScheduler to allow time travel
+			AtomicLong time = new AtomicLong(System.currentTimeMillis());
+			clock = new SettableClock(time);
+			TestTaskScheduler testTaskScheduler = new TestTaskScheduler(clock);
+			taskScheduler = testTaskScheduler;
+			timeTravel = new TimeTravel() {
+				@Override
+				public void setCurrentTimeMillis(long now)
+						throws InterruptedException {
+					time.set(now);
+					testTaskScheduler.runTasks();
+				}
+
+				@Override
+				public void addCurrentTimeMillis(long add)
+						throws InterruptedException {
+					time.addAndGet(add);
+					testTaskScheduler.runTasks();
+				}
+			};
+		} else {
+			// Use the default clock and task scheduler
+			clock = new SystemClock();
+			taskScheduler = new TaskSchedulerImpl(scheduledExecutorService);
+			timeTravel = new TimeTravel() {
+				@Override
+				public void setCurrentTimeMillis(long now) {
+					throw new UnsupportedOperationException();
+				}
+
+				@Override
+				public void addCurrentTimeMillis(long add) {
+					throw new UnsupportedOperationException();
+				}
+			};
+		}
+	}
+
+	@Provides
+	Clock provideClock() {
+		return clock;
+	}
+
+	@Provides
+	@Singleton
+	TaskScheduler provideTaskScheduler(LifecycleManager lifecycleManager) {
+		lifecycleManager.registerForShutdown(scheduledExecutorService);
+		return taskScheduler;
+	}
+
+	@Provides
+	TimeTravel provideTimeTravel() {
+		return timeTravel;
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/test/BrambleCoreIntegrationTestModule.java

@@ -3,8 +3,8 @@ package org.briarproject.bramble.test;
 import org.briarproject.bramble.api.FeatureFlags;
 import org.briarproject.bramble.battery.DefaultBatteryManagerModule;
 import org.briarproject.bramble.event.DefaultEventExecutorModule;
-import org.briarproject.bramble.system.DefaultTaskSchedulerModule;
 import org.briarproject.bramble.system.DefaultWakefulIoExecutorModule;
+import org.briarproject.bramble.system.TimeTravelModule;
 
 import dagger.Module;
 import dagger.Provides;
@@ -12,11 +12,11 @@ import dagger.Provides;
 @Module(includes = {
 		DefaultBatteryManagerModule.class,
 		DefaultEventExecutorModule.class,
-		DefaultTaskSchedulerModule.class,
 		DefaultWakefulIoExecutorModule.class,
 		TestDatabaseConfigModule.class,
 		TestPluginConfigModule.class,
-		TestSecureRandomModule.class
+		TestSecureRandomModule.class,
+		TimeTravelModule.class
 })
 public class BrambleCoreIntegrationTestModule {
 
@@ -33,6 +33,11 @@ public class BrambleCoreIntegrationTestModule {
 			public boolean shouldEnableProfilePictures() {
 				return true;
 			}
+
+			@Override
+			public boolean shouldEnableDisappearingMessages() {
+				return true;
+			}
 		};
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/versioning/ClientVersioningManagerImplTest.java

@@ -38,7 +38,6 @@ import static org.briarproject.bramble.test.TestUtils.getContact;
 import static org.briarproject.bramble.test.TestUtils.getGroup;
 import static org.briarproject.bramble.test.TestUtils.getMessage;
 import static org.briarproject.bramble.test.TestUtils.getRandomId;
-import static org.briarproject.bramble.versioning.ClientVersioningConstants.GROUP_KEY_CONTACT_ID;
 import static org.briarproject.bramble.versioning.ClientVersioningConstants.MSG_KEY_LOCAL;
 import static org.briarproject.bramble.versioning.ClientVersioningConstants.MSG_KEY_UPDATE_VERSION;
 import static org.junit.Assert.assertEquals;
@@ -60,8 +59,6 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 	private final ClientId clientId = getClientId();
 	private final long now = System.currentTimeMillis();
 	private final Transaction txn = new Transaction(null, false);
-	private final BdfDictionary groupMeta = BdfDictionary.of(
-			new BdfEntry(GROUP_KEY_CONTACT_ID, contact.getId().getInt()));
 
 	private ClientVersioningManagerImpl createInstance() {
 		context.checking(new Expectations() {{
@@ -123,8 +120,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).addGroup(txn, contactGroup);
 			oneOf(db).setGroupVisibility(txn, contact.getId(),
 					contactGroup.getId(), SHARED);
-			oneOf(clientHelper).mergeGroupMetadata(txn, contactGroup.getId(),
+			oneOf(clientHelper).setContactId(txn, contactGroup.getId(),
-					groupMeta);
+					contact.getId());
 			oneOf(clock).currentTimeMillis();
 			will(returnValue(now));
 			oneOf(clientHelper).createMessage(contactGroup.getId(), now,
@@ -460,9 +457,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).deleteMessage(txn, oldRemoteUpdateId);
 			oneOf(db).deleteMessageMetadata(txn, oldRemoteUpdateId);
 			// Get contact ID
-			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+			oneOf(clientHelper).getContactId(txn, contactGroup.getId());
-					contactGroup.getId());
+			will(returnValue(contact.getId()));
-			will(returnValue(groupMeta));
 			// No states or visibilities have changed
 		}});
 
@@ -492,10 +488,9 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			// Load the latest local update
 			oneOf(clientHelper).getMessageAsList(txn, oldLocalUpdateId);
 			will(returnValue(oldLocalUpdateBody));
-			// Get client ID
+			// Get contact ID
-			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+			oneOf(clientHelper).getContactId(txn, contactGroup.getId());
-					contactGroup.getId());
+			will(returnValue(contact.getId()));
-			will(returnValue(groupMeta));
 			// No states or visibilities have changed
 		}});
 
@@ -546,8 +541,6 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 		BdfDictionary newLocalUpdateMeta = BdfDictionary.of(
 				new BdfEntry(MSG_KEY_UPDATE_VERSION, 2L),
 				new BdfEntry(MSG_KEY_LOCAL, true));
-		BdfDictionary groupMeta = BdfDictionary.of(
-				new BdfEntry(GROUP_KEY_CONTACT_ID, contact.getId().getInt()));
 
 		context.checking(new Expectations() {{
 			oneOf(clientHelper).toList(newRemoteUpdate);
@@ -577,9 +570,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).addLocalMessage(txn, newLocalUpdate,
 					newLocalUpdateMeta, true, false);
 			// The client's visibility has changed
-			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+			oneOf(clientHelper).getContactId(txn, contactGroup.getId());
-					contactGroup.getId());
+			will(returnValue(contact.getId()));
-			will(returnValue(groupMeta));
 			oneOf(db).getContact(txn, contact.getId());
 			will(returnValue(contact));
 			oneOf(hook).onClientVisibilityChanging(txn, contact, visibility);
@@ -619,8 +611,6 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 		BdfDictionary newLocalUpdateMeta = BdfDictionary.of(
 				new BdfEntry(MSG_KEY_UPDATE_VERSION, 2L),
 				new BdfEntry(MSG_KEY_LOCAL, true));
-		BdfDictionary groupMeta = BdfDictionary.of(
-				new BdfEntry(GROUP_KEY_CONTACT_ID, contact.getId().getInt()));
 
 		context.checking(new Expectations() {{
 			oneOf(clientHelper).toList(newRemoteUpdate);
@@ -650,9 +640,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).addLocalMessage(txn, newLocalUpdate,
 					newLocalUpdateMeta, true, false);
 			// The client's visibility has changed
-			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+			oneOf(clientHelper).getContactId(txn, contactGroup.getId());
-					contactGroup.getId());
+			will(returnValue(contact.getId()));
-			will(returnValue(groupMeta));
 			oneOf(db).getContact(txn, contact.getId());
 			will(returnValue(contact));
 			oneOf(hook).onClientVisibilityChanging(txn, contact, INVISIBLE);

bramble-java/build.gradle

@@ -16,7 +16,7 @@ dependencies {
 	implementation fileTree(dir: 'libs', include: '*.jar')
 	implementation 'net.java.dev.jna:jna:4.5.2'
 	implementation 'net.java.dev.jna:jna-platform:4.5.2'
-	tor 'org.briarproject:tor:0.3.5.13-1@zip'
+	tor 'org.briarproject:tor:0.3.5.13@zip'
 	tor 'org.briarproject:obfs4proxy:0.0.12-dev-40245c4a@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'

bramble-java/src/main/java/org/briarproject/bramble/BrambleJavaModule.java

@@ -8,9 +8,9 @@ import org.briarproject.bramble.system.JavaSystemModule;
 import dagger.Module;
 
 @Module(includes = {
+		CircumventionModule.class,
 		JavaNetworkModule.class,
 		JavaSystemModule.class,
-		CircumventionModule.class,
 		SocksModule.class
 })
 public class BrambleJavaModule {

bramble-java/src/main/java/org/briarproject/bramble/plugin/tor/UnixTorPluginFactory.java

@@ -25,7 +25,6 @@ import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 import javax.net.SocketFactory;
 
-import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.OsUtils.isLinux;
 
@@ -97,15 +96,8 @@ public class UnixTorPluginFactory implements DuplexPluginFactory {
 		String architecture = null;
 		if (isLinux()) {
 			String arch = System.getProperty("os.arch");
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("System's os.arch is " + arch);
-			}
 			if (arch.equals("amd64")) {
 				architecture = "linux-x86_64";
-			} else if (arch.equals("aarch64")) {
-				architecture = "linux-aarch64";
-			} else if (arch.equals("arm")) {
-				architecture = "linux-armhf";
 			}
 		}
 		if (architecture == null) {
@@ -113,10 +105,6 @@ public class UnixTorPluginFactory implements DuplexPluginFactory {
 			return null;
 		}
 
-		if (LOG.isLoggable(INFO)) {
-			LOG.info("The selected architecture for Tor is " + architecture);
-		}
-
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		TorRendezvousCrypto torRendezvousCrypto = new TorRendezvousCryptoImpl();

bramble-java/witness.gradle

@@ -24,7 +24,7 @@ dependencyVerification {
         'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.briarproject:obfs4proxy:0.0.12-dev-40245c4a:obfs4proxy-0.0.12-dev-40245c4a.zip:172029e7058b3a83ac93ac4991a44bf76e16ce8d46f558f5836d57da3cb3a766',
-        'org.briarproject:tor:0.3.5.13-1:tor-0.3.5.13-1.zip:ef35c16bf8dc1f4c75ed71d9f55e4514f383d124ec96b859aca647c990927c99',
+        'org.briarproject:tor:0.3.5.13:tor-0.3.5.13.zip:1c5f0b821ee2aadb0ea04aa96caab3ca0a08370cce8de81c2dfe04d172f8a2a0',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',

briar-android/build.gradle

@@ -19,15 +19,11 @@ android {
 	compileSdkVersion 30
 	buildToolsVersion '30.0.2'
 
-	packagingOptions {
-		doNotStrip '**/*.so'
-	}
-
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 29
-		versionCode 10220
+		versionCode 10216
-		versionName "1.2.20"
+		versionName "1.2.16"
 		applicationId "org.briarproject.briar.android"
 
 		vectorDrawables.useSupportLibrary = true

briar-android/src/androidTest/java/org/briarproject/briar/android/UiTest.java

@@ -4,20 +4,16 @@ import android.app.Activity;
 import android.content.Intent;
 
 import org.briarproject.bramble.api.account.AccountManager;
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.settings.Settings;
-import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.briar.R;
 
+import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.test.espresso.intent.rule.IntentsTestRule;
 
 import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
-import static org.briarproject.briar.android.controller.BriarControllerImpl.DOZE_ASK_AGAIN;
-import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
 
 
 @SuppressWarnings("WeakerAccess")
@@ -31,8 +27,6 @@ public abstract class UiTest {
 	protected AccountManager accountManager;
 	@Inject
 	protected LifecycleManager lifecycleManager;
-	@Inject
-	protected SettingsManager settingsManager;
 
 	public UiTest() {
 		BriarTestComponentApplication app = getApplicationContext();
@@ -45,8 +39,22 @@ public abstract class UiTest {
 	protected class CleanAccountTestRule<A extends Activity>
 			extends IntentsTestRule<A> {
 
+		@Nullable
+		private final Runnable runnable;
+
 		public CleanAccountTestRule(Class<A> activityClass) {
 			super(activityClass);
+			this.runnable = null;
+		}
+
+		/**
+		 * Use this if you need to run code before launching the activity.
+		 * Note: You need to use {@link #launchActivity(Intent)} yourself
+		 * to start the activity.
+		 */
+		public CleanAccountTestRule(Class<A> activityClass, Runnable runnable) {
+			super(activityClass, false, false);
+			this.runnable = runnable;
 		}
 
 		@Override
@@ -54,17 +62,16 @@ public abstract class UiTest {
 			super.beforeActivityLaunched();
 			accountManager.deleteAccount();
 			accountManager.createAccount(USERNAME, PASSWORD);
-			Intent serviceIntent =
+			if (runnable != null) {
-					new Intent(getApplicationContext(), BriarService.class);
+				Intent serviceIntent =
-			getApplicationContext().startService(serviceIntent);
+						new Intent(getApplicationContext(), BriarService.class);
-			try {
+				getApplicationContext().startService(serviceIntent);
-				lifecycleManager.waitForStartup();
+				try {
-				// do not show doze white-listing dialog
+					lifecycleManager.waitForStartup();
-				Settings settings = new Settings();
+				} catch (InterruptedException e) {
-				settings.putBoolean(DOZE_ASK_AGAIN, false);
+					throw new AssertionError(e);
-				settingsManager.mergeSettings(settings, SETTINGS_NAMESPACE);
+				}
-			} catch (InterruptedException | DbException e) {
+				runnable.run();
-				throw new AssertionError(e);
 			}
 		}
 	}

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/BriarUiTestComponent.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android;
 import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.bramble.account.BriarAccountModule;
+import org.briarproject.bramble.system.ClockModule;
 import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.android.attachment.AttachmentModule;
 import org.briarproject.briar.android.attachment.media.MediaModule;
@@ -16,6 +17,7 @@ import dagger.Component;
 @Component(modules = {
 		AppModule.class,
 		AttachmentModule.class,
+		ClockModule.class,
 		MediaModule.class,
 		BriarCoreModule.class,
 		BrambleAndroidModule.class,

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/media/PngSuiteImageCompressorTest.java

@@ -10,15 +10,12 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.logging.Logger;
 
-import androidx.test.filters.LargeTest;
-
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.test.TestUtils.isOptionalTestEnabled;
 import static org.junit.Assert.fail;
 import static org.junit.Assume.assumeTrue;
 
-@LargeTest
 @RunWith(Parameterized.class)
 public class PngSuiteImageCompressorTest
 		extends AbstractImageCompressorTest {

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/media/PngSuiteImageSizeCalculatorTest.java

@@ -12,14 +12,11 @@ import java.util.List;
 import java.util.Map;
 import java.util.logging.Logger;
 
-import androidx.test.filters.LargeTest;
-
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.test.TestUtils.isOptionalTestEnabled;
 import static org.junit.Assume.assumeTrue;
 
-@LargeTest
 @RunWith(Parameterized.class)
 public class PngSuiteImageSizeCalculatorTest
 		extends AbstractImageSizeCalculatorTest {

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/conversation/ConversationActivityNotSignedInTest.java

@@ -0,0 +1,39 @@
+package org.briarproject.briar.android.conversation;
+
+import android.content.Context;
+import android.content.Intent;
+
+import org.briarproject.briar.R;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.rule.ActivityTestRule;
+
+import static androidx.test.espresso.Espresso.onView;
+import static androidx.test.espresso.matcher.ViewMatchers.isDisplayed;
+import static androidx.test.espresso.matcher.ViewMatchers.withText;
+import static androidx.test.platform.app.InstrumentationRegistry.getInstrumentation;
+import static org.briarproject.briar.android.ViewActions.waitUntilMatches;
+import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
+
+@RunWith(AndroidJUnit4.class)
+public class ConversationActivityNotSignedInTest {
+
+	@Rule
+	public ActivityTestRule<ConversationActivity> testRule =
+			new ActivityTestRule<>(ConversationActivity.class, false, false);
+
+	@Test
+	public void openWithoutSignedIn() {
+		Context targetContext = getInstrumentation().getTargetContext();
+		Intent intent = new Intent(targetContext, ConversationActivity.class);
+		intent.putExtra(CONTACT_ID, 1);
+		testRule.launchActivity(intent);
+
+		onView(withText(R.string.sign_in_button))
+				.perform(waitUntilMatches(isDisplayed()));
+	}
+
+}

briar-android/src/androidTestScreenshot/java/org/briarproject/briar/android/BriarUiTestComponent.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android;
 import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.bramble.account.BriarAccountModule;
+import org.briarproject.bramble.system.ClockModule;
 import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.android.attachment.AttachmentModule;
 import org.briarproject.briar.android.attachment.media.MediaModule;
@@ -17,6 +18,7 @@ import dagger.Component;
 @Component(modules = {
 		AppModule.class,
 		AttachmentModule.class,
+		ClockModule.class,
 		MediaModule.class,
 		BriarCoreModule.class,
 		BrambleAndroidModule.class,

briar-android/src/androidTestScreenshot/java/org/briarproject/briar/android/settings/SettingsActivityScreenshotTest.java

@@ -16,7 +16,6 @@ import androidx.test.espresso.contrib.DrawerActions;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import androidx.test.rule.ActivityTestRule;
 
-import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
 import static androidx.test.espresso.Espresso.onView;
 import static androidx.test.espresso.action.ViewActions.click;
 import static androidx.test.espresso.assertion.ViewAssertions.matches;
@@ -30,9 +29,7 @@ import static androidx.test.espresso.matcher.ViewMatchers.withClassName;
 import static androidx.test.espresso.matcher.ViewMatchers.withId;
 import static androidx.test.espresso.matcher.ViewMatchers.withText;
 import static org.briarproject.briar.android.ViewActions.waitUntilMatches;
-import static org.briarproject.briar.android.util.UiUtils.hasScreenLock;
 import static org.hamcrest.CoreMatchers.is;
-import static org.junit.Assume.assumeTrue;
 
 @RunWith(AndroidJUnit4.class)
 public class SettingsActivityScreenshotTest extends ScreenshotTest {
@@ -79,8 +76,6 @@ public class SettingsActivityScreenshotTest extends ScreenshotTest {
 
 	@Test
 	public void appLock() {
-		assumeTrue("device has no screen lock",
-				hasScreenLock(getApplicationContext()));
 		// scroll down
 		onView(withClassName(is(RecyclerView.class.getName())))
 				.perform(scrollTo(hasDescendant(

briar-android/src/main/AndroidManifest.xml

@@ -27,10 +27,7 @@
 	<uses-permission android:name="android.permission.USE_FINGERPRINT" />
 	<uses-permission android:name="android.permission.VIBRATE" />
 	<uses-permission android:name="android.permission.WAKE_LOCK" />
-	<uses-permission
+	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
-		android:name="android.permission.WRITE_EXTERNAL_STORAGE"
-		android:maxSdkVersion="18"
-		tools:ignore="ScopedStorage" />
 
 	<uses-permission-sdk-23 android:name="android.permission.ACCESS_FINE_LOCATION" />
 	<uses-permission-sdk-23 android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS" />
@@ -41,7 +38,6 @@
 		android:name="org.briarproject.briar.android.BriarApplicationImpl"
 		android:allowBackup="false"
 		android:banner="@mipmap/tv_banner"
-		android:fullBackupContent="@xml/backup_rules"
 		android:icon="@mipmap/ic_launcher_round"
 		android:label="@string/app_name"
 		android:logo="@mipmap/ic_launcher_round"

briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java

@@ -29,6 +29,7 @@ import org.briarproject.bramble.api.system.AndroidWakeLockManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.plugin.tor.CircumventionProvider;
+import org.briarproject.bramble.system.ClockModule;
 import org.briarproject.briar.BriarCoreEagerSingletons;
 import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.android.attachment.AttachmentModule;
@@ -42,6 +43,7 @@ import org.briarproject.briar.api.android.DozeWatchdog;
 import org.briarproject.briar.api.android.LockManager;
 import org.briarproject.briar.api.android.ScreenFilterMonitor;
 import org.briarproject.briar.api.attachment.AttachmentReader;
+import org.briarproject.briar.api.autodelete.AutoDeleteManager;
 import org.briarproject.briar.api.blog.BlogManager;
 import org.briarproject.briar.api.blog.BlogPostFactory;
 import org.briarproject.briar.api.blog.BlogSharingManager;
@@ -76,6 +78,7 @@ import dagger.Component;
 		BriarAccountModule.class,
 		AppModule.class,
 		AttachmentModule.class,
+		ClockModule.class,
 		MediaModule.class
 })
 public interface AndroidComponent
@@ -184,6 +187,8 @@ public interface AndroidComponent
 
 	Thread.UncaughtExceptionHandler exceptionHandler();
 
+	AutoDeleteManager autoDeleteManager();
+
 	void inject(SignInReminderReceiver briarService);
 
 	void inject(BriarService briarService);

briar-android/src/main/java/org/briarproject/briar/android/AndroidNotificationManagerImpl.java

@@ -37,6 +37,7 @@ import org.briarproject.briar.android.splash.SplashScreenActivity;
 import org.briarproject.briar.android.util.BriarNotificationBuilder;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
+import org.briarproject.briar.api.conversation.ConversationResponse;
 import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
 import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
 import org.briarproject.briar.api.privategroup.event.GroupMessageAddedEvent;
@@ -226,6 +227,12 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		} else if (e instanceof ConversationMessageReceivedEvent) {
 			ConversationMessageReceivedEvent<?> p =
 					(ConversationMessageReceivedEvent<?>) e;
+			if (p.getMessageHeader() instanceof ConversationResponse) {
+				ConversationResponse r =
+						(ConversationResponse) p.getMessageHeader();
+				// don't show notification for own auto-decline responses
+				if (r.isAutoDecline()) return;
+			}
 			showContactNotification(p.getContactId());
 		} else if (e instanceof GroupMessageAddedEvent) {
 			GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -30,10 +30,8 @@ import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.android.account.DozeHelperModule;
 import org.briarproject.briar.android.account.LockManagerImpl;
 import org.briarproject.briar.android.account.SetupModule;
-import org.briarproject.briar.android.blog.BlogModule;
 import org.briarproject.briar.android.contact.ContactListModule;
 import org.briarproject.briar.android.forum.ForumModule;
-import org.briarproject.briar.android.introduction.IntroductionModule;
 import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
 import org.briarproject.briar.android.logging.LoggingModule;
 import org.briarproject.briar.android.login.LoginModule;
@@ -84,9 +82,7 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		SettingsModule.class,
 		DevReportModule.class,
 		ContactListModule.class,
-		IntroductionModule.class,
 		// below need to be within same scope as ViewModelProvider.Factory
-		BlogModule.class,
 		ForumModule.class,
 		GroupListModule.class,
 		GroupConversationModule.class,
@@ -287,6 +283,11 @@ public class AppModule {
 			public boolean shouldEnableProfilePictures() {
 				return IS_DEBUG_BUILD;
 			}
+
+			@Override
+			public boolean shouldEnableDisappearingMessages() {
+				return IS_DEBUG_BUILD;
+			}
 		};
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/account/DozeFragment.java

@@ -33,6 +33,7 @@ public class DozeFragment extends SetupFragment
 	private DozeView dozeView;
 	private HuaweiView huaweiView;
 	private Button next;
+	private ProgressBar progressBar;
 	private boolean secondAttempt = false;
 
 	public static DozeFragment newInstance() {
@@ -57,19 +58,11 @@ public class DozeFragment extends SetupFragment
 		huaweiView = v.findViewById(R.id.huaweiView);
 		huaweiView.setOnCheckedChangedListener(this);
 		next = v.findViewById(R.id.next);
-		ProgressBar progressBar = v.findViewById(R.id.progress);
+		progressBar = v.findViewById(R.id.progress);
 
 		dozeView.setOnButtonClickListener(this::askForDozeWhitelisting);
 		next.setOnClickListener(this);
 
-		viewModel.getIsCreatingAccount()
-				.observe(getViewLifecycleOwner(), isCreatingAccount -> {
-					if (isCreatingAccount) {
-						next.setVisibility(INVISIBLE);
-						progressBar.setVisibility(VISIBLE);
-					}
-				});
-
 		return v;
 	}
 
@@ -111,6 +104,15 @@ public class DozeFragment extends SetupFragment
 
 	@Override
 	public void onClick(View view) {
+		setNextClicked();
 		viewModel.dozeExceptionConfirmed();
 	}
+
+	@Override
+	void setNextClicked() {
+		super.setNextClicked();
+
+		next.setVisibility(INVISIBLE);
+		progressBar.setVisibility(VISIBLE);
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/account/SetPasswordFragment.java

@@ -38,6 +38,7 @@ public class SetPasswordFragment extends SetupFragment {
 	private TextInputEditText passwordConfirmation;
 	private StrengthMeter strengthMeter;
 	private Button nextButton;
+	private ProgressBar progressBar;
 
 	public static SetPasswordFragment newInstance() {
 		return new SetPasswordFragment();
@@ -63,7 +64,7 @@ public class SetPasswordFragment extends SetupFragment {
 				v.findViewById(R.id.password_confirm_wrapper);
 		passwordConfirmation = v.findViewById(R.id.password_confirm);
 		nextButton = v.findViewById(R.id.next);
-		ProgressBar progressBar = v.findViewById(R.id.progress);
+		progressBar = v.findViewById(R.id.progress);
 
 		passwordEntry.addTextChangedListener(this);
 		passwordConfirmation.addTextChangedListener(this);
@@ -74,17 +75,6 @@ public class SetPasswordFragment extends SetupFragment {
 			passwordConfirmation.setImeOptions(IME_ACTION_DONE);
 		}
 
-		viewModel.getIsCreatingAccount()
-				.observe(getViewLifecycleOwner(), isCreatingAccount -> {
-					if (isCreatingAccount) {
-						nextButton.setVisibility(INVISIBLE);
-						progressBar.setVisibility(VISIBLE);
-						// this also avoids the keyboard popping up
-						passwordEntry.setFocusable(false);
-						passwordConfirmation.setFocusable(false);
-					}
-				});
-
 		return v;
 	}
 
@@ -126,6 +116,20 @@ public class SetPasswordFragment extends SetupFragment {
 		IBinder token = passwordEntry.getWindowToken();
 		Object o = getContext().getSystemService(INPUT_METHOD_SERVICE);
 		((InputMethodManager) o).hideSoftInputFromWindow(token, 0);
+
+		setNextClicked();
 		viewModel.setPassword(passwordEntry.getText().toString());
 	}
+
+	@Override
+	void setNextClicked() {
+		super.setNextClicked();
+
+		passwordEntry.setFocusable(false);
+		passwordConfirmation.setFocusable(false);
+		if (!viewModel.needToShowDozeFragment()) {
+			nextButton.setVisibility(INVISIBLE);
+			progressBar.setVisibility(VISIBLE);
+		}
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/account/SetupFragment.java

@@ -7,6 +7,7 @@ import android.view.KeyEvent;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
+import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.TextView;
 import android.widget.TextView.OnEditorActionListener;
@@ -18,6 +19,8 @@ import org.briarproject.briar.android.fragment.BaseFragment;
 
 import javax.inject.Inject;
 
+import androidx.annotation.CallSuper;
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.lifecycle.ViewModelProvider;
 
@@ -32,6 +35,7 @@ abstract class SetupFragment extends BaseFragment implements TextWatcher,
 		OnEditorActionListener, OnClickListener {
 
 	private final static String STATE_KEY_CLICKED = "setupFragmentClicked";
+	private boolean clicked = false;
 
 	@Inject
 	ViewModelProvider.Factory viewModelFactory;
@@ -44,6 +48,27 @@ abstract class SetupFragment extends BaseFragment implements TextWatcher,
 				.get(SetupViewModel.class);
 	}
 
+	@Override
+	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+		if (savedInstanceState != null) {
+			clicked = savedInstanceState.getBoolean(STATE_KEY_CLICKED);
+		}
+		if (clicked) {
+			setNextClicked();
+		}
+	}
+
+	@Override
+	public void onSaveInstanceState(@NonNull Bundle outState) {
+		super.onSaveInstanceState(outState);
+		outState.putBoolean(STATE_KEY_CLICKED, clicked);
+	}
+
+	@CallSuper
+	void setNextClicked() {
+		this.clicked = true;
+	}
+
 	@Override
 	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
 		inflater.inflate(R.menu.help_action, menu);
@@ -89,4 +114,5 @@ abstract class SetupFragment extends BaseFragment implements TextWatcher,
 	public void afterTextChanged(Editable editable) {
 		// noop
 	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/account/SetupViewModel.java

@@ -17,8 +17,6 @@ import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.lifecycle.AndroidViewModel;
-import androidx.lifecycle.LiveData;
-import androidx.lifecycle.MutableLiveData;
 
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.android.account.SetupViewModel.State.AUTHOR_NAME;
@@ -38,8 +36,6 @@ class SetupViewModel extends AndroidViewModel {
 	@Nullable
 	private String authorName, password;
 	private final MutableLiveEvent<State> state = new MutableLiveEvent<>();
-	private final MutableLiveData<Boolean> isCreatingAccount =
-			new MutableLiveData<>(false);
 
 	private final AccountManager accountManager;
 	private final Executor ioExecutor;
@@ -71,10 +67,6 @@ class SetupViewModel extends AndroidViewModel {
 		return state;
 	}
 
-	LiveData<Boolean> getIsCreatingAccount() {
-		return isCreatingAccount;
-	}
-
 	void setAuthorName(String authorName) {
 		this.authorName = authorName;
 		state.setEvent(SET_PASSWORD);
@@ -105,7 +97,6 @@ class SetupViewModel extends AndroidViewModel {
 	private void createAccount() {
 		if (authorName == null) throw new IllegalStateException();
 		if (password == null) throw new IllegalStateException();
-		isCreatingAccount.setValue(true);
 		ioExecutor.execute(() -> {
 			if (accountManager.createAccount(authorName, password)) {
 				LOG.info("Created account");

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -11,8 +11,10 @@ import org.briarproject.briar.android.account.SetupActivity;
 import org.briarproject.briar.android.account.UnlockActivity;
 import org.briarproject.briar.android.blog.BlogActivity;
 import org.briarproject.briar.android.blog.BlogFragment;
+import org.briarproject.briar.android.blog.BlogModule;
 import org.briarproject.briar.android.blog.BlogPostFragment;
 import org.briarproject.briar.android.blog.FeedFragment;
+import org.briarproject.briar.android.blog.FeedPostFragment;
 import org.briarproject.briar.android.blog.ReblogActivity;
 import org.briarproject.briar.android.blog.ReblogFragment;
 import org.briarproject.briar.android.blog.RssFeedImportActivity;
@@ -25,6 +27,7 @@ import org.briarproject.briar.android.contact.add.remote.NicknameFragment;
 import org.briarproject.briar.android.contact.add.remote.PendingContactListActivity;
 import org.briarproject.briar.android.conversation.AliasDialogFragment;
 import org.briarproject.briar.android.conversation.ConversationActivity;
+import org.briarproject.briar.android.conversation.ConversationSettingsDialog;
 import org.briarproject.briar.android.conversation.ImageActivity;
 import org.briarproject.briar.android.conversation.ImageFragment;
 import org.briarproject.briar.android.forum.CreateForumActivity;
@@ -83,6 +86,7 @@ import dagger.Component;
 @ActivityScope
 @Component(modules = {
 		ActivityModule.class,
+		BlogModule.class,
 		CreateGroupModule.class,
 		GroupInvitationModule.class,
 		GroupMemberModule.class,
@@ -149,6 +153,8 @@ public interface ActivityComponent {
 
 	void inject(BlogPostFragment fragment);
 
+	void inject(FeedPostFragment fragment);
+
 	void inject(ReblogFragment fragment);
 
 	void inject(ReblogActivity activity);
@@ -233,4 +239,6 @@ public interface ActivityComponent {
 
 	void inject(ConfirmAvatarDialogFragment fragment);
 
+	void inject(ConversationSettingsDialog dialog);
+
 }

briar-android/src/main/java/org/briarproject/briar/android/activity/RequestCodes.java

@@ -6,6 +6,7 @@ public interface RequestCodes {
 	int REQUEST_INTRODUCTION = 2;
 	int REQUEST_GROUP_INVITE = 3;
 	int REQUEST_SHARE_FORUM = 4;
+	int REQUEST_WRITE_BLOG_POST = 5;
 	int REQUEST_SHARE_BLOG = 6;
 	int REQUEST_RINGTONE = 7;
 	int REQUEST_PERMISSION_CAMERA_LOCATION = 8;

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentRetrieverImpl.java

@@ -28,12 +28,9 @@ import javax.inject.Inject;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
-import static java.util.Arrays.asList;
 import static java.util.Objects.requireNonNull;
-import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.AndroidUtils.getSupportedImageContentTypes;
 import static org.briarproject.bramble.util.IoUtils.tryToClose;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
@@ -89,17 +86,7 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 		List<AttachmentHeader> headers = messageHeader.getAttachmentHeaders();
 		List<LiveData<AttachmentItem>> items = new ArrayList<>(headers.size());
 		boolean needsSize = headers.size() == 1;
-		List<String> supported = asList(getSupportedImageContentTypes());
 		for (AttachmentHeader h : headers) {
-			// Fail early if we don't support the content type
-			if (!supported.contains(h.getContentType())) {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Unsupported content type " + h.getContentType());
-				}
-				AttachmentItem item = new AttachmentItem(h, "", ERROR);
-				items.add(new MutableLiveData<>(item));
-				continue;
-			}
 			// try cache for existing item live data
 			MutableLiveData<AttachmentItem> liveData =
 					itemsWithSize.get(h.getMessageId());

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseController.java

@@ -0,0 +1,48 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.controller.handler.ExceptionHandler;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+
+import java.util.Collection;
+
+import javax.annotation.Nullable;
+
+import androidx.annotation.UiThread;
+
+@NotNullByDefault
+interface BaseController {
+
+	@UiThread
+	void onStart();
+
+	@UiThread
+	void onStop();
+
+	void loadBlogPosts(GroupId g,
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
+
+	void loadBlogPost(BlogPostHeader header,
+			ResultExceptionHandler<BlogPostItem, DbException> handler);
+
+	void loadBlogPost(GroupId g, MessageId m,
+			ResultExceptionHandler<BlogPostItem, DbException> handler);
+
+	void repeatPost(BlogPostItem item, @Nullable String comment,
+			ExceptionHandler<DbException> handler);
+
+	@NotNullByDefault
+	interface BlogListener {
+
+		@UiThread
+		void onBlogPostAdded(BlogPostHeader header, boolean local);
+
+		@UiThread
+		void onBlogRemoved();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseControllerImpl.java

@@ -0,0 +1,209 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.controller.DbControllerImpl;
+import org.briarproject.briar.android.controller.handler.ExceptionHandler;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogCommentHeader;
+import org.briarproject.briar.api.blog.BlogManager;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+import org.briarproject.briar.util.HtmlUtils;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import androidx.annotation.CallSuper;
+
+import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.util.HtmlUtils.ARTICLE;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+abstract class BaseControllerImpl extends DbControllerImpl
+		implements BaseController, EventListener {
+
+	private static final Logger LOG =
+			Logger.getLogger(BaseControllerImpl.class.getName());
+
+	protected final EventBus eventBus;
+	protected final AndroidNotificationManager notificationManager;
+	protected final IdentityManager identityManager;
+	protected final BlogManager blogManager;
+
+	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
+	private final Map<MessageId, BlogPostHeader> headerCache =
+			new ConcurrentHashMap<>();
+
+	BaseControllerImpl(@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager, EventBus eventBus,
+			AndroidNotificationManager notificationManager,
+			IdentityManager identityManager, BlogManager blogManager) {
+		super(dbExecutor, lifecycleManager);
+		this.eventBus = eventBus;
+		this.notificationManager = notificationManager;
+		this.identityManager = identityManager;
+		this.blogManager = blogManager;
+	}
+
+	@Override
+	@CallSuper
+	public void onStart() {
+		eventBus.addListener(this);
+	}
+
+	@Override
+	@CallSuper
+	public void onStop() {
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void loadBlogPosts(GroupId groupId,
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
+		runOnDbThread(() -> {
+			try {
+				Collection<BlogPostItem> items = loadItems(groupId);
+				handler.onResult(items);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	Collection<BlogPostItem> loadItems(GroupId groupId) throws DbException {
+		long start = now();
+		Collection<BlogPostHeader> headers =
+				blogManager.getPostHeaders(groupId);
+		logDuration(LOG, "Loading headers", start);
+		Collection<BlogPostItem> items = new ArrayList<>(headers.size());
+		start = now();
+		for (BlogPostHeader h : headers) {
+			headerCache.put(h.getId(), h);
+			BlogPostItem item = getItem(h);
+			items.add(item);
+		}
+		logDuration(LOG, "Loading bodies", start);
+		return items;
+	}
+
+	@Override
+	public void loadBlogPost(BlogPostHeader header,
+			ResultExceptionHandler<BlogPostItem, DbException> handler) {
+
+		String text = textCache.get(header.getId());
+		if (text != null) {
+			LOG.info("Loaded text from cache");
+			handler.onResult(new BlogPostItem(header, text));
+			return;
+		}
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				BlogPostItem item = getItem(header);
+				logDuration(LOG, "Loading text", start);
+				handler.onResult(item);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	@Override
+	public void loadBlogPost(GroupId g, MessageId m,
+			ResultExceptionHandler<BlogPostItem, DbException> handler) {
+
+		BlogPostHeader header = headerCache.get(m);
+		if (header != null) {
+			LOG.info("Loaded header from cache");
+			loadBlogPost(header, handler);
+			return;
+		}
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				BlogPostHeader header1 = getPostHeader(g, m);
+				BlogPostItem item = getItem(header1);
+				logDuration(LOG, "Loading post", start);
+				handler.onResult(item);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	@Override
+	public void repeatPost(BlogPostItem item, @Nullable String comment,
+			ExceptionHandler<DbException> handler) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor a = identityManager.getLocalAuthor();
+				Blog b = blogManager.getPersonalBlog(a);
+				BlogPostHeader h = item.getHeader();
+				blogManager.addLocalComment(a, b.getId(), comment, h);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	private BlogPostHeader getPostHeader(GroupId g, MessageId m)
+			throws DbException {
+		BlogPostHeader header = headerCache.get(m);
+		if (header == null) {
+			header = blogManager.getPostHeader(g, m);
+			headerCache.put(m, header);
+		}
+		return header;
+	}
+
+	@DatabaseExecutor
+	private BlogPostItem getItem(BlogPostHeader h) throws DbException {
+		String text;
+		if (h instanceof BlogCommentHeader) {
+			BlogCommentHeader c = (BlogCommentHeader) h;
+			BlogCommentItem item = new BlogCommentItem(c);
+			text = getPostText(item.getPostHeader().getId());
+			item.setText(text);
+			return item;
+		} else {
+			text = getPostText(h.getId());
+			return new BlogPostItem(h, text);
+		}
+	}
+
+	@DatabaseExecutor
+	private String getPostText(MessageId m) throws DbException {
+		String text = textCache.get(m);
+		if (text == null) {
+			text = HtmlUtils.clean(blogManager.getPostText(m), ARTICLE);
+			textCache.put(m, text);
+		}
+		return text;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BasePostFragment.java

@@ -0,0 +1,121 @@
+package org.briarproject.briar.android.blog;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.os.Handler;
+import android.os.Looper;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ProgressBar;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.fragment.BaseFragment;
+
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import androidx.annotation.CallSuper;
+import androidx.annotation.UiThread;
+
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static android.view.View.INVISIBLE;
+import static android.view.View.VISIBLE;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
+import static org.briarproject.briar.android.util.UiUtils.MIN_DATE_RESOLUTION;
+
+@UiThread
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+abstract class BasePostFragment extends BaseFragment {
+
+	static final String POST_ID = "briar.POST_ID";
+
+	private static final Logger LOG =
+			getLogger(BasePostFragment.class.getName());
+
+	private final Handler handler = new Handler(Looper.getMainLooper());
+
+	protected MessageId postId;
+	private ProgressBar progressBar;
+	private BlogPostViewHolder ui;
+	private BlogPostItem post;
+	private Runnable refresher;
+
+	@CallSuper
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		// retrieve MessageId of blog post from arguments
+		byte[] p = requireArguments().getByteArray(POST_ID);
+		if (p == null) throw new IllegalStateException("No post ID in args");
+		postId = new MessageId(p);
+
+		View view = inflater.inflate(R.layout.fragment_blog_post, container,
+				false);
+		progressBar = view.findViewById(R.id.progressBar);
+		progressBar.setVisibility(VISIBLE);
+		ui = new BlogPostViewHolder(view, true, new OnBlogPostClickListener() {
+			@Override
+			public void onBlogPostClick(BlogPostItem post) {
+				// We're already there
+			}
+
+			@Override
+			public void onAuthorClick(BlogPostItem post) {
+				if (getContext() == null) return;
+				Intent i = new Intent(getContext(), BlogActivity.class);
+				i.putExtra(GROUP_ID, post.getGroupId().getBytes());
+				i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+				getContext().startActivity(i);
+			}
+		}, getFragmentManager());
+		return view;
+	}
+
+	@CallSuper
+	@Override
+	public void onStart() {
+		super.onStart();
+		startPeriodicUpdate();
+	}
+
+	@CallSuper
+	@Override
+	public void onStop() {
+		super.onStop();
+		stopPeriodicUpdate();
+	}
+
+	@UiThread
+	protected void onBlogPostLoaded(BlogPostItem post) {
+		progressBar.setVisibility(INVISIBLE);
+		this.post = post;
+		ui.bindItem(post);
+	}
+
+	private void startPeriodicUpdate() {
+		refresher = () -> {
+			LOG.info("Updating Content...");
+			ui.updateDate(post.getTimestamp());
+			handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
+		};
+		LOG.info("Adding Handler Callback");
+		handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
+	}
+
+	private void stopPeriodicUpdate() {
+		if (refresher != null) {
+			LOG.info("Removing Handler Callback");
+			handler.removeCallbacks(refresher);
+		}
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseViewModel.java

@@ -1,216 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import android.app.Application;
-
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
-import org.briarproject.bramble.api.db.TransactionManager;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventListener;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.identity.LocalAuthor;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.briar.android.viewmodel.DbViewModel;
-import org.briarproject.briar.android.viewmodel.LiveResult;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.blog.Blog;
-import org.briarproject.briar.api.blog.BlogCommentHeader;
-import org.briarproject.briar.api.blog.BlogManager;
-import org.briarproject.briar.api.blog.BlogPostHeader;
-import org.briarproject.briar.util.HtmlUtils;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-
-import androidx.annotation.UiThread;
-import androidx.lifecycle.LiveData;
-import androidx.lifecycle.MutableLiveData;
-
-import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.util.HtmlUtils.ARTICLE;
-
-@NotNullByDefault
-abstract class BaseViewModel extends DbViewModel implements EventListener {
-
-	private static final Logger LOG = getLogger(BaseViewModel.class.getName());
-
-	private final EventBus eventBus;
-	protected final IdentityManager identityManager;
-	protected final AndroidNotificationManager notificationManager;
-	protected final BlogManager blogManager;
-
-	protected final MutableLiveData<LiveResult<ListUpdate>> blogPosts =
-			new MutableLiveData<>();
-
-	BaseViewModel(Application application,
-			@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager,
-			TransactionManager db,
-			AndroidExecutor androidExecutor,
-			EventBus eventBus,
-			IdentityManager identityManager,
-			AndroidNotificationManager notificationManager,
-			BlogManager blogManager) {
-		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
-		this.eventBus = eventBus;
-		this.identityManager = identityManager;
-		this.notificationManager = notificationManager;
-		this.blogManager = blogManager;
-		eventBus.addListener(this);
-	}
-
-	@Override
-	protected void onCleared() {
-		super.onCleared();
-		eventBus.removeListener(this);
-	}
-
-	@DatabaseExecutor
-	protected List<BlogPostItem> loadBlogPosts(Transaction txn, GroupId groupId)
-			throws DbException {
-		long start = now();
-		List<BlogPostHeader> headers =
-				blogManager.getPostHeaders(txn, groupId);
-		logDuration(LOG, "Loading headers", start);
-		List<BlogPostItem> items = new ArrayList<>(headers.size());
-		start = now();
-		for (BlogPostHeader h : headers) {
-			BlogPostItem item = getItem(txn, h);
-			items.add(item);
-		}
-		logDuration(LOG, "Loading bodies", start);
-		return items;
-	}
-
-	@DatabaseExecutor
-	protected BlogPostItem getItem(Transaction txn, BlogPostHeader h)
-			throws DbException {
-		String text;
-		if (h instanceof BlogCommentHeader) {
-			BlogCommentHeader c = (BlogCommentHeader) h;
-			BlogCommentItem item = new BlogCommentItem(c);
-			text = getPostText(txn, item.getPostHeader().getId());
-			item.setText(text);
-			return item;
-		} else {
-			text = getPostText(txn, h.getId());
-			return new BlogPostItem(h, text);
-		}
-	}
-
-	@DatabaseExecutor
-	private String getPostText(Transaction txn, MessageId m)
-			throws DbException {
-		return HtmlUtils.clean(blogManager.getPostText(txn, m), ARTICLE);
-	}
-
-	LiveData<LiveResult<BlogPostItem>> loadBlogPost(GroupId g, MessageId m) {
-		MutableLiveData<LiveResult<BlogPostItem>> result =
-				new MutableLiveData<>();
-		runOnDbThread(true, txn -> {
-			long start = now();
-			BlogPostHeader header = blogManager.getPostHeader(txn, g, m);
-			BlogPostItem item = getItem(txn, header);
-			logDuration(LOG, "Loading post", start);
-			result.postValue(new LiveResult<>(item));
-		}, e -> {
-			logException(LOG, WARNING, e);
-			result.postValue(new LiveResult<>(e));
-		});
-		return result;
-	}
-
-	protected void onBlogPostAdded(BlogPostHeader header, boolean local) {
-		runOnDbThread(true, txn -> {
-			BlogPostItem item = getItem(txn, header);
-			txn.attach(() -> onBlogPostItemAdded(item, local));
-		}, this::handleException);
-	}
-
-	@UiThread
-	private void onBlogPostItemAdded(BlogPostItem item, boolean local) {
-		List<BlogPostItem> items = addListItem(getBlogPostItems(), item);
-		if (items != null) {
-			Collections.sort(items);
-			blogPosts.setValue(new LiveResult<>(new ListUpdate(local, items)));
-		}
-	}
-
-	void repeatPost(BlogPostItem item, @Nullable String comment) {
-		runOnDbThread(() -> {
-			try {
-				LocalAuthor a = identityManager.getLocalAuthor();
-				Blog b = blogManager.getPersonalBlog(a);
-				BlogPostHeader h = item.getHeader();
-				blogManager.addLocalComment(a, b.getId(), comment, h);
-			} catch (DbException e) {
-				handleException(e);
-			}
-		});
-	}
-
-	LiveData<LiveResult<ListUpdate>> getBlogPosts() {
-		return blogPosts;
-	}
-
-	@UiThread
-	@Nullable
-	protected List<BlogPostItem> getBlogPostItems() {
-		LiveResult<ListUpdate> value = blogPosts.getValue();
-		if (value == null) return null;
-		ListUpdate result = value.getResultOrNull();
-		return result == null ? null : result.getItems();
-	}
-
-	/**
-	 * Call this after {@link ListUpdate#getPostAddedWasLocal()} was processed.
-	 * This prevents it from getting processed again.
-	 */
-	@UiThread
-	void resetLocalUpdate() {
-		LiveResult<ListUpdate> value = blogPosts.getValue();
-		if (value == null) return;
-		ListUpdate result = value.getResultOrNull();
-		result.postAddedWasLocal = null;
-	}
-
-	static class ListUpdate {
-
-		@Nullable
-		private Boolean postAddedWasLocal;
-		private final List<BlogPostItem> items;
-
-		ListUpdate(@Nullable Boolean postAddedWasLocal,
-				List<BlogPostItem> items) {
-			this.postAddedWasLocal = postAddedWasLocal;
-			this.items = items;
-		}
-
-		/**
-		 * @return null when not a single post was added with this update.
-		 * true when a single post was added locally and false if remotely.
-		 */
-		@Nullable
-		public Boolean getPostAddedWasLocal() {
-			return postAddedWasLocal;
-		}
-
-		public List<BlogPostItem> getItems() {
-			return items;
-		}
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogActivity.java

@@ -6,11 +6,9 @@ import android.os.Bundle;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
-import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 import org.briarproject.briar.android.sharing.BlogSharingStatusActivity;
 
@@ -18,10 +16,6 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.appcompat.widget.Toolbar;
-import androidx.lifecycle.ViewModelProvider;
-
-import static java.util.Objects.requireNonNull;
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -29,16 +23,7 @@ public class BlogActivity extends BriarActivity
 		implements BaseFragmentListener {
 
 	@Inject
-	ViewModelProvider.Factory viewModelFactory;
+	BlogController blogController;
-
-	private BlogViewModel viewModel;
-
-	@Override
-	public void injectActivity(ActivityComponent component) {
-		component.inject(this);
-		viewModel = new ViewModelProvider(this, viewModelFactory)
-				.get(BlogViewModel.class);
-	}
 
 	@Override
 	public void onCreate(@Nullable Bundle state) {
@@ -46,46 +31,32 @@ public class BlogActivity extends BriarActivity
 
 		// GroupId from Intent
 		Intent i = getIntent();
-		GroupId groupId =
+		byte[] b = i.getByteArrayExtra(GROUP_ID);
-				new GroupId(requireNonNull(i.getByteArrayExtra(GROUP_ID)));
+		if (b == null) throw new IllegalStateException("No group ID in intent");
-		// Get post info from intent
+		GroupId groupId = new GroupId(b);
-		@Nullable byte[] postId = i.getByteArrayExtra(POST_ID);
+		blogController.setGroupId(groupId);
-
-		viewModel.setGroupId(groupId, postId == null);
 
 		setContentView(R.layout.activity_fragment_container_toolbar);
 		Toolbar toolbar = setUpCustomToolbar(false);
 
 		// Open Sharing Status on Toolbar click
-		toolbar.setOnClickListener(v -> {
+		if (toolbar != null) {
-			Intent i1 = new Intent(BlogActivity.this,
+			toolbar.setOnClickListener(v -> {
-					BlogSharingStatusActivity.class);
+				Intent i1 = new Intent(BlogActivity.this,
-			i1.putExtra(GROUP_ID, groupId.getBytes());
+						BlogSharingStatusActivity.class);
-			startActivity(i1);
+				i1.putExtra(GROUP_ID, groupId.getBytes());
-		});
+				startActivity(i1);
-
+			});
-		viewModel.getBlog().observe(this, blog ->
+		}
-				setTitle(blog.getBlog().getAuthor().getName())
-		);
-		viewModel.getSharingInfo().observe(this, info ->
-				setToolbarSubTitle(info.total, info.online)
-		);
 
 		if (state == null) {
-			if (postId == null) {
+			showInitialFragment(BlogFragment.newInstance(groupId));
-				showInitialFragment(BlogFragment.newInstance(groupId));
-			} else {
-				MessageId messageId = new MessageId(postId);
-				BaseFragment f =
-						BlogPostFragment.newInstance(groupId, messageId);
-				showInitialFragment(f);
-			}
 		}
 	}
 
-	private void setToolbarSubTitle(int total, int online) {
+	@Override
-		requireNonNull(getSupportActionBar())
+	public void injectActivity(ActivityComponent component) {
-				.setSubtitle(getString(R.string.shared_with, total, online));
+		component.inject(this);
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogCommentItem.java

@@ -8,9 +8,7 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 
-import javax.annotation.concurrent.NotThreadSafe;
+// This class is not thread-safe
-
-@NotThreadSafe
 class BlogCommentItem extends BlogPostItem {
 
 	private static final BlogCommentComparator COMPARATOR =

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogController.java

@@ -0,0 +1,46 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+
+import java.util.Collection;
+
+import androidx.annotation.UiThread;
+
+@NotNullByDefault
+public interface BlogController extends BaseController {
+
+	void setGroupId(GroupId g);
+
+	@UiThread
+	void setBlogSharingListener(BlogSharingListener listener);
+
+	@UiThread
+	void unsetBlogSharingListener(BlogSharingListener listener);
+
+	void loadBlogPosts(
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
+
+	void loadBlogPost(MessageId m,
+			ResultExceptionHandler<BlogPostItem, DbException> handler);
+
+	void loadBlog(ResultExceptionHandler<BlogItem, DbException> handler);
+
+	void deleteBlog(ResultExceptionHandler<Void, DbException> handler);
+
+	void loadSharingContacts(
+			ResultExceptionHandler<Collection<ContactId>, DbException> handler);
+
+	interface BlogSharingListener extends BlogListener {
+		@UiThread
+		void onBlogInvitationAccepted(ContactId c);
+
+		@UiThread
+		void onBlogLeft(ContactId c);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogControllerImpl.java

@@ -1,24 +1,24 @@
 package org.briarproject.briar.android.blog;
 
-import android.app.Application;
+import android.app.Activity;
 
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
-import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.controller.ActivityLifecycleController;
-import org.briarproject.briar.android.sharing.SharingController;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.android.sharing.SharingController.SharingInfo;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.blog.Blog;
 import org.briarproject.briar.api.blog.BlogInvitationResponse;
@@ -35,54 +35,85 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import androidx.annotation.UiThread;
+import androidx.annotation.Nullable;
-import androidx.lifecycle.LiveData;
-import androidx.lifecycle.MutableLiveData;
 
-import static java.util.logging.Logger.getLogger;
+import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class BlogViewModel extends BaseViewModel {
+class BlogControllerImpl extends BaseControllerImpl
+		implements ActivityLifecycleController, BlogController, EventListener {
 
-	private static final Logger LOG = getLogger(BlogViewModel.class.getName());
+	private static final Logger LOG =
+			Logger.getLogger(BlogControllerImpl.class.getName());
 
 	private final BlogSharingManager blogSharingManager;
-	private final SharingController sharingController;
 
-	private volatile GroupId groupId;
+	// UI thread
+	@Nullable
+	private BlogSharingListener listener;
 
-	private final MutableLiveData<BlogItem> blog = new MutableLiveData<>();
+	private volatile GroupId groupId = null;
-	private final MutableLiveData<Boolean> blogRemoved =
-			new MutableLiveData<>();
 
 	@Inject
-	BlogViewModel(Application application,
+	BlogControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager, EventBus eventBus,
-			LifecycleManager lifecycleManager,
-			TransactionManager db,
-			AndroidExecutor androidExecutor,
-			EventBus eventBus,
-			IdentityManager identityManager,
 			AndroidNotificationManager notificationManager,
-			BlogManager blogManager,
+			IdentityManager identityManager, BlogManager blogManager,
-			BlogSharingManager blogSharingManager,
+			BlogSharingManager blogSharingManager) {
-			SharingController sharingController) {
+		super(dbExecutor, lifecycleManager, eventBus, notificationManager,
-		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				identityManager, blogManager);
-				eventBus, identityManager, notificationManager, blogManager);
 		this.blogSharingManager = blogSharingManager;
-		this.sharingController = sharingController;
+	}
+
+	@Override
+	public void onActivityCreate(Activity activity) {
+	}
+
+	@Override
+	public void onActivityStart() {
+		super.onStart();
+		notificationManager.blockNotification(groupId);
+		notificationManager.clearBlogPostNotification(groupId);
+	}
+
+	@Override
+	public void onActivityStop() {
+		super.onStop();
+		notificationManager.unblockNotification(groupId);
+	}
+
+	@Override
+	public void onActivityDestroy() {
+	}
+
+	@Override
+	public void setGroupId(GroupId g) {
+		groupId = g;
+	}
+
+	@Override
+	public void setBlogSharingListener(BlogSharingListener listener) {
+		this.listener = listener;
+	}
+
+	@Override
+	public void unsetBlogSharingListener(BlogSharingListener listener) {
+		if (this.listener == listener) this.listener = null;
 	}
 
 	@Override
 	public void eventOccurred(Event e) {
+		if (groupId == null || listener == null)
+			throw new IllegalStateException();
 		if (e instanceof BlogPostAddedEvent) {
 			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
 			if (b.getGroupId().equals(groupId)) {
 				LOG.info("Blog post added");
-				onBlogPostAdded(b.getHeader(), b.isLocal());
+				listener.onBlogPostAdded(b.getHeader(), b.isLocal());
 			}
 		} else if (e instanceof BlogInvitationResponseReceivedEvent) {
 			BlogInvitationResponseReceivedEvent b =
@@ -90,36 +121,41 @@ class BlogViewModel extends BaseViewModel {
 			BlogInvitationResponse r = b.getMessageHeader();
 			if (r.getShareableId().equals(groupId) && r.wasAccepted()) {
 				LOG.info("Blog invitation accepted");
-				sharingController.add(b.getContactId());
+				listener.onBlogInvitationAccepted(b.getContactId());
 			}
 		} else if (e instanceof ContactLeftShareableEvent) {
 			ContactLeftShareableEvent s = (ContactLeftShareableEvent) e;
 			if (s.getGroupId().equals(groupId)) {
 				LOG.info("Blog left by contact");
-				sharingController.remove(s.getContactId());
+				listener.onBlogLeft(s.getContactId());
 			}
 		} else if (e instanceof GroupRemovedEvent) {
 			GroupRemovedEvent g = (GroupRemovedEvent) e;
 			if (g.getGroup().getId().equals(groupId)) {
 				LOG.info("Blog removed");
-				blogRemoved.setValue(true);
+				listener.onBlogRemoved();
 			}
 		}
 	}
 
-	/**
+	@Override
-	 * Set this before calling any other methods.
+	public void loadBlogPosts(
-	 */
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
-	@UiThread
+		if (groupId == null) throw new IllegalStateException();
-	public void setGroupId(GroupId groupId, boolean loadAllPosts) {
+		loadBlogPosts(groupId, handler);
-		if (this.groupId == groupId) return; // configuration change
-		this.groupId = groupId;
-		loadBlog(groupId);
-		if (loadAllPosts) loadBlogPosts(groupId);
-		loadSharingContacts(groupId);
 	}
 
-	private void loadBlog(GroupId groupId) {
+	@Override
+	public void loadBlogPost(MessageId m,
+			ResultExceptionHandler<BlogPostItem, DbException> handler) {
+		if (groupId == null) throw new IllegalStateException();
+		loadBlogPost(groupId, m, handler);
+	}
+
+	@Override
+	public void loadBlog(
+			ResultExceptionHandler<BlogItem, DbException> handler) {
+		if (groupId == null) throw new IllegalStateException();
 		runOnDbThread(() -> {
 			try {
 				long start = now();
@@ -127,65 +163,50 @@ class BlogViewModel extends BaseViewModel {
 				Blog b = blogManager.getBlog(groupId);
 				boolean ours = a.getId().equals(b.getAuthor().getId());
 				boolean removable = blogManager.canBeRemoved(b);
-				blog.postValue(new BlogItem(b, ours, removable));
+				BlogItem blog = new BlogItem(b, ours, removable);
 				logDuration(LOG, "Loading blog", start);
+				handler.onResult(blog);
 			} catch (DbException e) {
-				handleException(e);
+				logException(LOG, WARNING, e);
+				handler.onException(e);
 			}
 		});
 	}
 
-	void blockAndClearNotifications() {
+	@Override
-		notificationManager.blockNotification(groupId);
+	public void deleteBlog(ResultExceptionHandler<Void, DbException> handler) {
-		notificationManager.clearBlogPostNotification(groupId);
+		if (groupId == null) throw new IllegalStateException();
-	}
-
-	void unblockNotifications() {
-		notificationManager.unblockNotification(groupId);
-	}
-
-	private void loadBlogPosts(GroupId groupId) {
-		loadFromDb(txn -> new ListUpdate(null, loadBlogPosts(txn, groupId)),
-				blogPosts::setValue);
-	}
-
-	private void loadSharingContacts(GroupId groupId) {
-		runOnDbThread(true, txn -> {
-			Collection<Contact> contacts =
-					blogSharingManager.getSharedWith(txn, groupId);
-			txn.attach(() -> onSharingContactsLoaded(contacts));
-		}, this::handleException);
-	}
-
-	@UiThread
-	private void onSharingContactsLoaded(Collection<Contact> contacts) {
-		Collection<ContactId> contactIds = new ArrayList<>(contacts.size());
-		for (Contact c : contacts) contactIds.add(c.getId());
-		sharingController.addAll(contactIds);
-	}
-
-	void deleteBlog() {
 		runOnDbThread(() -> {
 			try {
 				long start = now();
 				Blog b = blogManager.getBlog(groupId);
 				blogManager.removeBlog(b);
 				logDuration(LOG, "Removing blog", start);
+				handler.onResult(null);
 			} catch (DbException e) {
-				handleException(e);
+				logException(LOG, WARNING, e);
+				handler.onException(e);
 			}
 		});
 	}
 
-	LiveData<BlogItem> getBlog() {
+	@Override
-		return blog;
+	public void loadSharingContacts(
+			ResultExceptionHandler<Collection<ContactId>, DbException> handler) {
+		if (groupId == null) throw new IllegalStateException();
+		runOnDbThread(() -> {
+			try {
+				Collection<Contact> contacts =
+						blogSharingManager.getSharedWith(groupId);
+				Collection<ContactId> contactIds =
+						new ArrayList<>(contacts.size());
+				for (Contact c : contacts) contactIds.add(c.getId());
+				handler.onResult(contactIds);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
 	}
 
-	LiveData<Boolean> getBlogRemoved() {
-		return blogRemoved;
-	}
-
-	LiveData<SharingInfo> getSharingInfo() {
-		return sharingController.getSharingInfo();
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -1,7 +1,9 @@
 package org.briarproject.briar.android.blog;
 
+import android.content.DialogInterface;
 import android.content.Intent;
 import android.os.Bundle;
+import android.os.Parcelable;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -10,25 +12,33 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Toast;
 
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.blog.BaseViewModel.ListUpdate;
+import org.briarproject.briar.android.activity.BriarActivity;
+import org.briarproject.briar.android.blog.BlogController.BlogSharingListener;
+import org.briarproject.briar.android.controller.SharingController;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.sharing.BlogSharingStatusActivity;
 import org.briarproject.briar.android.sharing.ShareBlogActivity;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
-import org.briarproject.briar.android.widget.LinkDialogFragment;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+
+import java.util.Collection;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
+import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.AlertDialog;
-import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView.LayoutManager;
 
@@ -38,22 +48,31 @@ import static android.widget.Toast.LENGTH_SHORT;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SHARE_BLOG;
+import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
+import static org.briarproject.briar.android.controller.SharingController.SharingListener;
 
 @UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class BlogFragment extends BaseFragment
-		implements OnBlogPostClickListener {
+		implements BlogSharingListener, SharingListener,
+		OnBlogPostClickListener {
 
 	private final static String TAG = BlogFragment.class.getName();
 
 	@Inject
-	ViewModelProvider.Factory viewModelFactory;
+	BlogController blogController;
+	@Inject
+	SharingController sharingController;
+	@Nullable
+	private Parcelable layoutManagerState;
 
 	private GroupId groupId;
-	private BlogViewModel viewModel;
+	private BlogPostAdapter adapter;
-	private final BlogPostAdapter adapter = new BlogPostAdapter(false, this);
+	private LayoutManager layoutManager;
 	private BriarRecyclerView list;
+	private MenuItem writeButton, deleteButton;
+	private boolean isMyBlog = false, canDeleteBlog = false;
 
 	static BlogFragment newInstance(GroupId groupId) {
 		BlogFragment f = new BlogFragment();
@@ -68,8 +87,8 @@ public class BlogFragment extends BaseFragment
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+		blogController.setBlogSharingListener(this);
-				.get(BlogViewModel.class);
+		sharingController.setSharingListener(this);
 	}
 
 	@Nullable
@@ -84,82 +103,106 @@ public class BlogFragment extends BaseFragment
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
+		adapter = new BlogPostAdapter(requireActivity(), this,
+				getFragmentManager());
 		list = v.findViewById(R.id.postList);
-		LayoutManager layoutManager = new LinearLayoutManager(getActivity());
+		layoutManager = new LinearLayoutManager(getActivity());
 		list.setLayoutManager(layoutManager);
 		list.setAdapter(adapter);
 		list.showProgressBar();
 		list.setEmptyText(getString(R.string.blogs_other_blog_empty_state));
 
-		viewModel.getBlogPosts().observe(getViewLifecycleOwner(), result ->
+		if (savedInstanceState != null) {
-				result.onError(this::handleException)
+			layoutManagerState =
-						.onSuccess(this::onBlogPostsLoaded)
+					savedInstanceState.getParcelable("layoutManager");
-		);
+		}
-		viewModel.getBlogRemoved().observe(getViewLifecycleOwner(), removed -> {
+
-			if (removed) finish();
-		});
 		return v;
 	}
 
 	@Override
 	public void onStart() {
 		super.onStart();
-		viewModel.blockAndClearNotifications();
+		sharingController.onStart();
+		loadBlog();
+		loadSharedContacts();
+		loadBlogPosts(false);
 		list.startPeriodicUpdate();
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		viewModel.unblockNotifications();
+		sharingController.onStop();
 		list.stopPeriodicUpdate();
 	}
 
+	@Override
+	public void onDestroy() {
+		super.onDestroy();
+		blogController.unsetBlogSharingListener(this);
+		sharingController.unsetSharingListener(this);
+	}
+
+	@Override
+	public void onSaveInstanceState(Bundle outState) {
+		super.onSaveInstanceState(outState);
+		if (layoutManager != null) {
+			layoutManagerState = layoutManager.onSaveInstanceState();
+			outState.putParcelable("layoutManager", layoutManagerState);
+		}
+	}
+
 	@Override
 	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
 		inflater.inflate(R.menu.blogs_blog_actions, menu);
-		MenuItem writeButton = menu.findItem(R.id.action_write_blog_post);
+		writeButton = menu.findItem(R.id.action_write_blog_post);
-		MenuItem deleteButton = menu.findItem(R.id.action_blog_delete);
+		if (isMyBlog) writeButton.setVisible(true);
-		viewModel.getBlog().observe(getViewLifecycleOwner(), blog -> {
+		deleteButton = menu.findItem(R.id.action_blog_delete);
-			if (blog.isOurs()) writeButton.setVisible(true);
+		if (canDeleteBlog) deleteButton.setEnabled(true);
-			if (blog.canBeRemoved()) deleteButton.setEnabled(true);
+
-		});
 		super.onCreateOptionsMenu(menu, inflater);
 	}
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		int itemId = item.getItemId();
+		switch (item.getItemId()) {
-		if (itemId == R.id.action_write_blog_post) {
+			case R.id.action_write_blog_post:
-			Intent i = new Intent(getActivity(), WriteBlogPostActivity.class);
+				Intent i = new Intent(getActivity(),
-			i.putExtra(GROUP_ID, groupId.getBytes());
+						WriteBlogPostActivity.class);
-			startActivity(i);
+				i.putExtra(GROUP_ID, groupId.getBytes());
-			return true;
+				startActivityForResult(i, REQUEST_WRITE_BLOG_POST);
-		} else if (itemId == R.id.action_blog_share) {
+				return true;
-			Intent i = new Intent(getActivity(), ShareBlogActivity.class);
+			case R.id.action_blog_share:
-			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+				Intent i2 = new Intent(getActivity(), ShareBlogActivity.class);
-			i.putExtra(GROUP_ID, groupId.getBytes());
+				i2.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-			startActivityForResult(i, REQUEST_SHARE_BLOG);
+				i2.putExtra(GROUP_ID, groupId.getBytes());
-			return true;
+				startActivityForResult(i2, REQUEST_SHARE_BLOG);
-		} else if (itemId == R.id.action_blog_sharing_status) {
+				return true;
-			Intent i =
+			case R.id.action_blog_sharing_status:
-					new Intent(getActivity(), BlogSharingStatusActivity.class);
+				Intent i3 = new Intent(getActivity(),
-			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+						BlogSharingStatusActivity.class);
-			i.putExtra(GROUP_ID, groupId.getBytes());
+				i3.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-			startActivity(i);
+				i3.putExtra(GROUP_ID, groupId.getBytes());
-			return true;
+				startActivity(i3);
-		} else if (itemId == R.id.action_blog_delete) {
+				return true;
-			showDeleteDialog();
+			case R.id.action_blog_delete:
-			return true;
+				showDeleteDialog();
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
 		}
-		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
 	public void onActivityResult(int request, int result,
 			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
-		if (request == REQUEST_SHARE_BLOG && result == RESULT_OK) {
+
+		if (request == REQUEST_WRITE_BLOG_POST && result == RESULT_OK) {
+			displaySnackbar(R.string.blogs_blog_post_created, true);
+			loadBlogPosts(true);
+		} else if (request == REQUEST_SHARE_BLOG && result == RESULT_OK) {
 			displaySnackbar(R.string.blogs_sharing_snackbar, false);
 		}
 	}
@@ -169,26 +212,35 @@ public class BlogFragment extends BaseFragment
 		return TAG;
 	}
 
-	private void onBlogPostsLoaded(ListUpdate update) {
+	@Override
-		adapter.submitList(update.getItems(), () -> {
+	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
-			Boolean wasLocal = update.getPostAddedWasLocal();
+		blogController.loadBlogPost(header,
-			if (wasLocal != null && wasLocal) {
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
-				list.scrollToPosition(0);
+						this) {
-				displaySnackbar(R.string.blogs_blog_post_created,
+					@Override
-						false);
+					public void onResultUi(BlogPostItem post) {
-			} else if (wasLocal != null) {
+						adapter.add(post);
-				displaySnackbar(R.string.blogs_blog_post_received,
+						if (local) {
-						true);
+							list.scrollToPosition(0);
-			}
+							displaySnackbar(R.string.blogs_blog_post_created,
-			viewModel.resetLocalUpdate();
+									false);
-			list.showData();
+						} else {
-		});
+							displaySnackbar(R.string.blogs_blog_post_received,
+									true);
+						}
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				}
+		);
 	}
 
 	@Override
 	public void onBlogPostClick(BlogPostItem post) {
-		BlogPostFragment f =
+		BlogPostFragment f = BlogPostFragment.newInstance(post.getId());
-				BlogPostFragment.newInstance(groupId, post.getId());
 		showNextFragment(f);
 	}
 
@@ -204,10 +256,111 @@ public class BlogFragment extends BaseFragment
 		getContext().startActivity(i);
 	}
 
+	private void loadBlogPosts(boolean reload) {
+		blogController.loadBlogPosts(
+				new UiResultExceptionHandler<Collection<BlogPostItem>,
+						DbException>(this) {
+					@Override
+					public void onResultUi(Collection<BlogPostItem> posts) {
+						if (posts.isEmpty()) {
+							list.showData();
+						} else {
+							adapter.addAll(posts);
+							if (reload || layoutManagerState == null) {
+								list.scrollToPosition(0);
+							} else {
+								layoutManager.onRestoreInstanceState(
+										layoutManagerState);
+							}
+						}
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	private void loadBlog() {
+		blogController.loadBlog(
+				new UiResultExceptionHandler<BlogItem, DbException>(this) {
+					@Override
+					public void onResultUi(BlogItem blog) {
+						setToolbarTitle(blog.getBlog().getAuthor());
+						if (blog.isOurs())
+							showWriteButton();
+						if (blog.canBeRemoved())
+							enableDeleteButton();
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	private void setToolbarTitle(Author a) {
+		getActivity().setTitle(a.getName());
+	}
+
+	private void loadSharedContacts() {
+		blogController.loadSharingContacts(
+				new UiResultExceptionHandler<Collection<ContactId>,
+						DbException>(this) {
+					@Override
+					public void onResultUi(Collection<ContactId> contacts) {
+						sharingController.addAll(contacts);
+						int online = sharingController.getOnlineCount();
+						setToolbarSubTitle(contacts.size(), online);
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
 	@Override
-	public void onLinkClick(String url) {
+	public void onBlogInvitationAccepted(ContactId c) {
-		LinkDialogFragment f = LinkDialogFragment.newInstance(url);
+		sharingController.add(c);
-		f.show(getParentFragmentManager(), f.getUniqueTag());
+		setToolbarSubTitle(sharingController.getTotalCount(),
+				sharingController.getOnlineCount());
+	}
+
+	@Override
+	public void onBlogLeft(ContactId c) {
+		sharingController.remove(c);
+		setToolbarSubTitle(sharingController.getTotalCount(),
+				sharingController.getOnlineCount());
+	}
+
+	@Override
+	public void onSharingInfoUpdated(int total, int online) {
+		setToolbarSubTitle(total, online);
+	}
+
+	private void setToolbarSubTitle(int total, int online) {
+		ActionBar actionBar =
+				((BriarActivity) getActivity()).getSupportActionBar();
+		if (actionBar != null) {
+			actionBar.setSubtitle(
+					getString(R.string.shared_with, total, online));
+		}
+	}
+
+	private void showWriteButton() {
+		isMyBlog = true;
+		if (writeButton != null)
+			writeButton.setVisible(true);
+	}
+
+	private void enableDeleteButton() {
+		canDeleteBlog = true;
+		if (deleteButton != null)
+			deleteButton.setEnabled(true);
 	}
 
 	private void displaySnackbar(int stringId, boolean scroll) {
@@ -220,21 +373,38 @@ public class BlogFragment extends BaseFragment
 	}
 
 	private void showDeleteDialog() {
-		AlertDialog.Builder builder = new AlertDialog.Builder(requireContext(),
+		DialogInterface.OnClickListener okListener =
+				(dialog, which) -> deleteBlog();
+		AlertDialog.Builder builder = new AlertDialog.Builder(getActivity(),
 				R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.blogs_remove_blog));
 		builder.setMessage(
 				getString(R.string.blogs_remove_blog_dialog_message));
 		builder.setPositiveButton(R.string.cancel, null);
-		builder.setNegativeButton(R.string.blogs_remove_blog_ok,
+		builder.setNegativeButton(R.string.blogs_remove_blog_ok, okListener);
-				(dialog, which) -> deleteBlog());
 		builder.show();
 	}
 
 	private void deleteBlog() {
-		viewModel.deleteBlog();
+		blogController.deleteBlog(
-		Toast.makeText(getActivity(), R.string.blogs_blog_removed, LENGTH_SHORT)
+				new UiResultExceptionHandler<Void, DbException>(this) {
-				.show();
+					@Override
+					public void onResultUi(Void result) {
+						Toast.makeText(getActivity(),
+								R.string.blogs_blog_removed, LENGTH_SHORT)
+								.show();
+						finish();
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	@Override
+	public void onBlogRemoved() {
 		finish();
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogModule.java

@@ -1,23 +1,35 @@
 package org.briarproject.briar.android.blog;
 
-import org.briarproject.briar.android.viewmodel.ViewModelKey;
+import org.briarproject.briar.android.activity.ActivityScope;
+import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.controller.SharingController;
+import org.briarproject.briar.android.controller.SharingControllerImpl;
 
-import androidx.lifecycle.ViewModel;
-import dagger.Binds;
 import dagger.Module;
-import dagger.multibindings.IntoMap;
+import dagger.Provides;
 
 @Module
-public interface BlogModule {
+public class BlogModule {
 
-	@Binds
+	@ActivityScope
-	@IntoMap
+	@Provides
-	@ViewModelKey(FeedViewModel.class)
+	BlogController provideBlogController(BaseActivity activity,
-	ViewModel bindFeedViewModel(FeedViewModel feedViewModel);
+			BlogControllerImpl blogController) {
+		activity.addLifecycleController(blogController);
+		return blogController;
+	}
 
-	@Binds
+	@ActivityScope
-	@IntoMap
+	@Provides
-	@ViewModelKey(BlogViewModel.class)
+	FeedController provideFeedController(FeedControllerImpl feedController) {
-	ViewModel bindBlogViewModel(BlogViewModel blogViewModel);
+		return feedController;
+	}
+
+	@ActivityScope
+	@Provides
+	SharingController provideSharingController(
+			SharingControllerImpl sharingController) {
+		return sharingController;
+	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostAdapter.java

@@ -1,5 +1,6 @@
 package org.briarproject.briar.android.blog;
 
+import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -7,44 +8,52 @@ import android.view.ViewGroup;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.util.BriarAdapter;
 
-import androidx.recyclerview.widget.DiffUtil;
+import androidx.annotation.Nullable;
-import androidx.recyclerview.widget.ListAdapter;
+import androidx.fragment.app.FragmentManager;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class BlogPostAdapter extends ListAdapter<BlogPostItem, BlogPostViewHolder> {
+class BlogPostAdapter extends BriarAdapter<BlogPostItem, BlogPostViewHolder> {
 
-	private final boolean authorClickable;
 	private final OnBlogPostClickListener listener;
+	@Nullable
+	private final FragmentManager fragmentManager;
 
-	BlogPostAdapter(boolean authorClickable, OnBlogPostClickListener listener) {
+	BlogPostAdapter(Context ctx, OnBlogPostClickListener listener,
-		super(new DiffUtil.ItemCallback<BlogPostItem>() {
+			@Nullable FragmentManager fragmentManager) {
-			@Override
+		super(ctx, BlogPostItem.class);
-			public boolean areItemsTheSame(BlogPostItem a, BlogPostItem b) {
-				return a.getId().equals(b.getId());
-			}
-
-			@Override
-			public boolean areContentsTheSame(BlogPostItem a, BlogPostItem b) {
-				return a.isRead() == b.isRead();
-			}
-		});
-		this.authorClickable = authorClickable;
 		this.listener = listener;
+		this.fragmentManager = fragmentManager;
 	}
 
 	@Override
 	public BlogPostViewHolder onCreateViewHolder(ViewGroup parent,
 			int viewType) {
-		View v = LayoutInflater.from(parent.getContext()).inflate(
+		View v = LayoutInflater.from(ctx).inflate(
 				R.layout.list_item_blog_post, parent, false);
-		return new BlogPostViewHolder(v, false, listener, authorClickable);
+		return new BlogPostViewHolder(v, false, listener, fragmentManager);
 	}
 
 	@Override
 	public void onBindViewHolder(BlogPostViewHolder ui, int position) {
-		ui.bindItem(getItem(position));
+		ui.bindItem(getItemAt(position));
+	}
+
+	@Override
+	public int compare(BlogPostItem a, BlogPostItem b) {
+		return a.compareTo(b);
+	}
+
+	@Override
+	public boolean areContentsTheSame(BlogPostItem a, BlogPostItem b) {
+		return a.isRead() == b.isRead();
+	}
+
+	@Override
+	public boolean areItemsTheSame(BlogPostItem a, BlogPostItem b) {
+		return a.getId().equals(b.getId());
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostFragment.java

@@ -1,159 +1,76 @@
 package org.briarproject.briar.android.blog;
 
-import android.content.Intent;
 import android.os.Bundle;
-import android.os.Handler;
-import android.os.Looper;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.ProgressBar;
 
+import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.android.blog.BaseController.BlogListener;
-import org.briarproject.briar.android.widget.LinkDialogFragment;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
+import org.briarproject.briar.api.blog.BlogPostHeader;
 
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
-import androidx.lifecycle.LifecycleOwner;
-import androidx.lifecycle.ViewModelProvider;
-
-import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
-import static android.view.View.INVISIBLE;
-import static android.view.View.VISIBLE;
-import static java.util.Objects.requireNonNull;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.util.UiUtils.MIN_DATE_RESOLUTION;
 
+@UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class BlogPostFragment extends BaseFragment
+public class BlogPostFragment extends BasePostFragment implements BlogListener {
-		implements OnBlogPostClickListener {
 
 	private static final String TAG = BlogPostFragment.class.getName();
-	private static final Logger LOG = getLogger(TAG);
-
-	static final String POST_ID = "briar.POST_ID";
-
-	protected BlogViewModel viewModel;
-	private final Handler handler = new Handler(Looper.getMainLooper());
-
-	private ProgressBar progressBar;
-	private BlogPostViewHolder ui;
-	private BlogPostItem post;
-	private Runnable refresher;
 
 	@Inject
-	ViewModelProvider.Factory viewModelFactory;
+	BlogController blogController;
 
-	static BlogPostFragment newInstance(GroupId blogId, MessageId postId) {
+	static BlogPostFragment newInstance(MessageId postId) {
 		BlogPostFragment f = new BlogPostFragment();
+
 		Bundle bundle = new Bundle();
-		bundle.putByteArray(GROUP_ID, blogId.getBytes());
 		bundle.putByteArray(POST_ID, postId.getBytes());
+
 		f.setArguments(bundle);
 		return f;
 	}
 
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
-				.get(BlogViewModel.class);
-	}
-
-	@Nullable
-	@Override
-	public View onCreateView(LayoutInflater inflater,
-			@Nullable ViewGroup container,
-			@Nullable Bundle savedInstanceState) {
-		Bundle args = requireArguments();
-		GroupId groupId =
-				new GroupId(requireNonNull(args.getByteArray(GROUP_ID)));
-		MessageId postId =
-				new MessageId(requireNonNull(args.getByteArray(POST_ID)));
-
-		View view = inflater.inflate(R.layout.fragment_blog_post, container,
-				false);
-		progressBar = view.findViewById(R.id.progressBar);
-		progressBar.setVisibility(VISIBLE);
-		ui = new BlogPostViewHolder(view, true, this, false);
-		LifecycleOwner owner = getViewLifecycleOwner();
-		viewModel.loadBlogPost(groupId, postId).observe(owner, result ->
-				result.onError(this::handleException)
-						.onSuccess(this::onBlogPostLoaded)
-		);
-		return view;
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		startPeriodicUpdate();
-	}
-
-	@Override
-	public void onStop() {
-		super.onStop();
-		stopPeriodicUpdate();
-	}
-
-	@UiThread
-	private void onBlogPostLoaded(BlogPostItem post) {
-		progressBar.setVisibility(INVISIBLE);
-		this.post = post;
-		ui.bindItem(post);
-	}
-
-	@Override
-	public void onBlogPostClick(BlogPostItem post) {
-		// We're already there
-	}
-
-	@Override
-	public void onAuthorClick(BlogPostItem post) {
-		Intent i = new Intent(requireContext(), BlogActivity.class);
-		i.putExtra(GROUP_ID, post.getGroupId().getBytes());
-		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-		requireContext().startActivity(i);
-	}
-
-	@Override
-	public void onLinkClick(String url) {
-		LinkDialogFragment f = LinkDialogFragment.newInstance(url);
-		f.show(getParentFragmentManager(), f.getUniqueTag());
-	}
-
-	private void startPeriodicUpdate() {
-		refresher = () -> {
-			LOG.info("Updating Content...");
-			ui.updateDate(post.getTimestamp());
-			handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
-		};
-		LOG.info("Adding Handler Callback");
-		handler.postDelayed(refresher, MIN_DATE_RESOLUTION);
-	}
-
-	private void stopPeriodicUpdate() {
-		if (refresher != null) {
-			LOG.info("Removing Handler Callback");
-			handler.removeCallbacks(refresher);
-		}
-	}
-
 	@Override
 	public String getUniqueTag() {
 		return TAG;
 	}
 
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		blogController.loadBlogPost(postId,
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
+						this) {
+					@Override
+					public void onResultUi(BlogPostItem post) {
+						onBlogPostLoaded(post);
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	@Override
+	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
+		// doesn't matter here
+	}
+
+	@Override
+	public void onBlogRemoved() {
+		finish();
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostItem.java

@@ -17,7 +17,7 @@ public class BlogPostItem implements Comparable<BlogPostItem> {
 	private final BlogPostHeader header;
 	@Nullable
 	protected String text;
-	private final boolean read;
+	private boolean read;
 
 	BlogPostItem(BlogPostHeader header, @Nullable String text) {
 		this.header = header;
@@ -74,6 +74,9 @@ public class BlogPostItem implements Comparable<BlogPostItem> {
 
 	protected static int compare(BlogPostHeader h1, BlogPostHeader h2) {
 		// The newest post comes first
-		return Long.compare(h2.getTimeReceived(), h1.getTimeReceived());
+		long aTime = h1.getTimeReceived(), bTime = h2.getTimeReceived();
+		if (aTime > bTime) return -1;
+		if (aTime < bTime) return 1;
+		return 0;
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostViewHolder.java

@@ -9,31 +9,31 @@ import android.view.ViewGroup;
 import android.widget.ImageButton;
 import android.widget.TextView;
 
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.view.AuthorView;
 import org.briarproject.briar.api.blog.BlogCommentHeader;
 import org.briarproject.briar.api.blog.BlogPostHeader;
 
+import javax.annotation.Nullable;
+
+import androidx.annotation.NonNull;
 import androidx.annotation.UiThread;
 import androidx.core.view.ViewCompat;
+import androidx.fragment.app.FragmentManager;
 import androidx.recyclerview.widget.RecyclerView;
 
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
+import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
 import static org.briarproject.briar.android.util.UiUtils.TEASER_LENGTH;
 import static org.briarproject.briar.android.util.UiUtils.getSpanned;
 import static org.briarproject.briar.android.util.UiUtils.getTeaser;
 import static org.briarproject.briar.android.util.UiUtils.makeLinksClickable;
-import static org.briarproject.briar.android.view.AuthorView.COMMENTER;
+import static org.briarproject.briar.api.blog.MessageType.POST;
-import static org.briarproject.briar.android.view.AuthorView.REBLOGGER;
-import static org.briarproject.briar.android.view.AuthorView.RSS_FEED_REBLOGGED;
 
 @UiThread
-@NotNullByDefault
 class BlogPostViewHolder extends RecyclerView.ViewHolder {
 
 	private final Context ctx;
@@ -43,16 +43,20 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 	private final ImageButton reblogButton;
 	private final TextView text;
 	private final ViewGroup commentContainer;
-	private final boolean fullText, authorClickable;
+	private final boolean fullText;
 
+	@NonNull
 	private final OnBlogPostClickListener listener;
+	@Nullable
+	private final FragmentManager fragmentManager;
 
 	BlogPostViewHolder(View v, boolean fullText,
-			OnBlogPostClickListener listener, boolean authorClickable) {
+			@NonNull OnBlogPostClickListener listener,
+			@Nullable FragmentManager fragmentManager) {
 		super(v);
 		this.fullText = fullText;
 		this.listener = listener;
-		this.authorClickable = authorClickable;
+		this.fragmentManager = fragmentManager;
 
 		ctx = v.getContext();
 		layout = v.findViewById(R.id.postLayout);
@@ -63,6 +67,10 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		commentContainer = v.findViewById(R.id.commentContainer);
 	}
 
+	void setVisibility(int visibility) {
+		layout.setVisibility(visibility);
+	}
+
 	void hideReblogButton() {
 		reblogButton.setVisibility(GONE);
 	}
@@ -79,15 +87,15 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		return "blogPost" + id.hashCode();
 	}
 
-	void bindItem(BlogPostItem item) {
+	void bindItem(@Nullable BlogPostItem item) {
+		if (item == null) return;
+
 		setTransitionName(item.getId());
 		if (!fullText) {
 			layout.setClickable(true);
 			layout.setOnClickListener(v -> listener.onBlogPostClick(item));
 		}
 
-		boolean isReblog = item instanceof BlogCommentItem;
-
 		// author and date
 		BlogPostHeader post = item.getPostHeader();
 		author.setAuthor(post.getAuthor(), post.getAuthorInfo());
@@ -95,7 +103,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		author.setPersona(
 				item.isRssFeed() ? AuthorView.RSS_FEED : AuthorView.NORMAL);
 		// TODO make author clickable more often #624
-		if (authorClickable && !isReblog) {
+		if (!fullText && item.getHeader().getType() == POST) {
 			author.setAuthorClickable(v -> listener.onAuthorClick(item));
 		} else {
 			author.setAuthorNotClickable();
@@ -106,7 +114,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		if (fullText) {
 			text.setText(postText);
 			text.setTextIsSelectable(true);
-			makeLinksClickable(text, listener::onLinkClick);
+			makeLinksClickable(text, fragmentManager);
 		} else {
 			text.setTextIsSelectable(false);
 			if (postText.length() > TEASER_LENGTH)
@@ -124,33 +132,32 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 
 		// comments
 		commentContainer.removeAllViews();
-		if (isReblog) {
+		if (item instanceof BlogCommentItem) {
-			onBindComment((BlogCommentItem) item, authorClickable);
+			onBindComment((BlogCommentItem) item);
 		} else {
 			reblogger.setVisibility(GONE);
 		}
 	}
 
-	private void onBindComment(BlogCommentItem item, boolean authorClickable) {
+	private void onBindComment(BlogCommentItem item) {
 		// reblogger
 		reblogger.setAuthor(item.getAuthor(), item.getAuthorInfo());
 		reblogger.setDate(item.getTimestamp());
-		if (authorClickable) {
+		if (!fullText) {
 			reblogger.setAuthorClickable(v -> listener.onAuthorClick(item));
-		} else {
-			reblogger.setAuthorNotClickable();
 		}
 		reblogger.setVisibility(VISIBLE);
-		reblogger.setPersona(REBLOGGER);
+		reblogger.setPersona(AuthorView.REBLOGGER);
 
 		author.setPersona(item.getHeader().getRootPost().isRssFeed() ?
-				RSS_FEED_REBLOGGED : COMMENTER);
+				AuthorView.RSS_FEED_REBLOGGED :
+				AuthorView.COMMENTER);
 
 		// comments
-		// TODO use nested RecyclerView instead like we do for Image Attachments
 		for (BlogCommentHeader c : item.getComments()) {
-			View v = LayoutInflater.from(ctx).inflate(
+			View v = LayoutInflater.from(ctx)
-					R.layout.list_item_blog_comment, commentContainer, false);
+					.inflate(R.layout.list_item_blog_comment,
+							commentContainer, false);
 
 			AuthorView author = v.findViewById(R.id.authorView);
 			TextView text = v.findViewById(R.id.textView);

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedController.java

@@ -0,0 +1,32 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.briar.api.blog.Blog;
+
+import java.util.Collection;
+
+import androidx.annotation.UiThread;
+
+@NotNullByDefault
+public interface FeedController extends BaseController {
+
+	void loadBlogPosts(
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
+
+	void loadPersonalBlog(ResultExceptionHandler<Blog, DbException> handler);
+
+	@UiThread
+	void setFeedListener(FeedListener listener);
+
+	@UiThread
+	void unsetFeedListener(FeedListener listener);
+
+	@NotNullByDefault
+	interface FeedListener extends BlogListener {
+
+		@UiThread
+		void onBlogAdded();
+	}
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedControllerImpl.java

@@ -0,0 +1,143 @@
+package org.briarproject.briar.android.blog;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.NoSuchGroupException;
+import org.briarproject.bramble.api.db.NoSuchMessageException;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
+import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
+import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogManager;
+import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.Nullable;
+
+import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.api.blog.BlogManager.CLIENT_ID;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class FeedControllerImpl extends BaseControllerImpl implements FeedController {
+
+	private static final Logger LOG =
+			Logger.getLogger(FeedControllerImpl.class.getName());
+
+	// UI thread
+	@Nullable
+	private FeedListener listener;
+
+	@Inject
+	FeedControllerImpl(@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager, EventBus eventBus,
+			AndroidNotificationManager notificationManager,
+			IdentityManager identityManager, BlogManager blogManager) {
+		super(dbExecutor, lifecycleManager, eventBus, notificationManager,
+				identityManager, blogManager);
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		if (listener == null) throw new IllegalStateException();
+		notificationManager.blockAllBlogPostNotifications();
+		notificationManager.clearAllBlogPostNotifications();
+	}
+
+	@Override
+	public void onStop() {
+		super.onStop();
+		notificationManager.unblockAllBlogPostNotifications();
+	}
+
+	@Override
+	public void setFeedListener(FeedListener listener) {
+		this.listener = listener;
+	}
+
+	@Override
+	public void unsetFeedListener(FeedListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (listener == null) throw new IllegalStateException();
+		if (e instanceof BlogPostAddedEvent) {
+			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
+			LOG.info("Blog post added");
+			listener.onBlogPostAdded(b.getHeader(), b.isLocal());
+		} else if (e instanceof GroupAddedEvent) {
+			GroupAddedEvent g = (GroupAddedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Blog added");
+				listener.onBlogAdded();
+			}
+		} else if (e instanceof GroupRemovedEvent) {
+			GroupRemovedEvent g = (GroupRemovedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Blog removed");
+				listener.onBlogRemoved();
+			}
+		}
+	}
+
+	@Override
+	public void loadBlogPosts(
+			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				Collection<BlogPostItem> posts = new ArrayList<>();
+				for (Blog b : blogManager.getBlogs()) {
+					try {
+						posts.addAll(loadItems(b.getId()));
+					} catch (NoSuchGroupException | NoSuchMessageException e) {
+						logException(LOG, WARNING, e);
+					}
+				}
+				logDuration(LOG, "Loading all posts", start);
+				handler.onResult(posts);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+	@Override
+	public void loadPersonalBlog(
+			ResultExceptionHandler<Blog, DbException> handler) {
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				Author a = identityManager.getLocalAuthor();
+				Blog b = blogManager.getPersonalBlog(a);
+				logDuration(LOG, "Loading personal blog", start);
+				handler.onResult(b);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onException(e);
+			}
+		});
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.blog;
 
 import android.content.Intent;
 import android.os.Bundle;
+import android.os.Parcelable;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -9,43 +10,53 @@ import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 
+import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.blog.BaseViewModel.ListUpdate;
+import org.briarproject.briar.android.blog.FeedController.FeedListener;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
-import org.briarproject.briar.android.widget.LinkDialogFragment;
 import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+
+import java.util.Collection;
+import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.lifecycle.ViewModelProvider;
+import androidx.annotation.UiThread;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
+import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
+import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
 
+@UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class FeedFragment extends BaseFragment
+public class FeedFragment extends BaseFragment implements
-		implements OnBlogPostClickListener {
+		OnBlogPostClickListener, FeedListener {
 
 	public final static String TAG = FeedFragment.class.getName();
+	private static final Logger LOG = Logger.getLogger(TAG);
 
 	@Inject
-	ViewModelProvider.Factory viewModelFactory;
+	FeedController feedController;
 
-	private FeedViewModel viewModel;
+	private BlogPostAdapter adapter;
-	private final BlogPostAdapter adapter = new BlogPostAdapter(true, this);
 	private LinearLayoutManager layoutManager;
 	private BriarRecyclerView list;
+	@Nullable
+	private Blog personalBlog;
+	@Nullable
+	private Parcelable layoutManagerState;
 
 	public static FeedFragment newInstance() {
 		FeedFragment f = new FeedFragment();
@@ -59,8 +70,7 @@ public class FeedFragment extends BaseFragment
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		viewModel = new ViewModelProvider(this, viewModelFactory)
+		feedController.setFeedListener(this);
-				.get(FeedViewModel.class);
 	}
 
 	@Nullable
@@ -72,6 +82,9 @@ public class FeedFragment extends BaseFragment
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
+		adapter =
+				new BlogPostAdapter(getActivity(), this, getFragmentManager());
+
 		layoutManager = new LinearLayoutManager(getActivity());
 		list = v.findViewById(R.id.postList);
 		list.setLayoutManager(layoutManager);
@@ -80,39 +93,103 @@ public class FeedFragment extends BaseFragment
 		list.setEmptyText(R.string.blogs_feed_empty_state);
 		list.setEmptyAction(R.string.blogs_feed_empty_state_action);
 
-		viewModel.getBlogPosts().observe(getViewLifecycleOwner(), result ->
+		if (savedInstanceState != null) {
-				result.onError(this::handleException)
+			layoutManagerState =
-						.onSuccess(this::onBlogPostsLoaded)
+					savedInstanceState.getParcelable("layoutManager");
-		);
+		}
 
 		return v;
 	}
 
+	@Override
+	public void onActivityResult(int requestCode, int resultCode,
+			@Nullable Intent data) {
+		super.onActivityResult(requestCode, resultCode, data);
+
+		// The BlogPostAddedEvent arrives when the controller is not listening
+		if (requestCode == REQUEST_WRITE_BLOG_POST && resultCode == RESULT_OK) {
+			showSnackBar(R.string.blogs_blog_post_created);
+		}
+	}
+
 	@Override
 	public void onStart() {
 		super.onStart();
-		viewModel.blockAndClearAllBlogPostNotifications();
+		feedController.onStart();
 		list.startPeriodicUpdate();
+		loadPersonalBlog();
+		loadBlogPosts(false);
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		viewModel.unblockAllBlogPostNotifications();
+		feedController.onStop();
+		adapter.clear();
+		list.showProgressBar();
 		list.stopPeriodicUpdate();
+		// TODO save list position in database/preferences?
 	}
 
-	private void onBlogPostsLoaded(ListUpdate update) {
+	@Override
-		adapter.submitList(update.getItems(), () -> {
+	public void onDestroy() {
-			Boolean wasLocal = update.getPostAddedWasLocal();
+		super.onDestroy();
-			if (wasLocal != null && wasLocal) {
+		feedController.unsetFeedListener(this);
-				showSnackBar(R.string.blogs_blog_post_created);
+	}
-			} else if (wasLocal != null) {
+
-				showSnackBar(R.string.blogs_blog_post_received);
+	@Override
-			}
+	public void onSaveInstanceState(Bundle outState) {
-			viewModel.resetLocalUpdate();
+		super.onSaveInstanceState(outState);
-			list.showData();
+		if (layoutManager != null) {
-		});
+			layoutManagerState = layoutManager.onSaveInstanceState();
+			outState.putParcelable("layoutManager", layoutManagerState);
+		}
+	}
+
+	private void loadPersonalBlog() {
+		feedController.loadPersonalBlog(
+				new UiResultExceptionHandler<Blog, DbException>(this) {
+					@Override
+					public void onResultUi(Blog b) {
+						personalBlog = b;
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+	private void loadBlogPosts(boolean clear) {
+		int revision = adapter.getRevision();
+		feedController.loadBlogPosts(
+				new UiResultExceptionHandler<Collection<BlogPostItem>, DbException>(
+						this) {
+					@Override
+					public void onResultUi(Collection<BlogPostItem> posts) {
+						if (revision == adapter.getRevision()) {
+							adapter.incrementRevision();
+							if (clear) adapter.setItems(posts);
+							else adapter.addAll(posts);
+							if (posts.isEmpty()) list.showData();
+							if (layoutManagerState == null) {
+								list.scrollToPosition(0);  // Scroll to the top
+							} else {
+								layoutManager.onRestoreInstanceState(
+										layoutManagerState);
+							}
+						} else {
+							LOG.info("Concurrent update, reloading");
+							loadBlogPosts(clear);
+						}
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
 	}
 
 	@Override
@@ -123,46 +200,67 @@ public class FeedFragment extends BaseFragment
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		int itemId = item.getItemId();
+		if (personalBlog == null) return false;
-		if (itemId == R.id.action_write_blog_post) {
+		switch (item.getItemId()) {
-			Blog personalBlog = viewModel.getPersonalBlog().getValue();
+			case R.id.action_write_blog_post:
-			if (personalBlog == null) return false;
+				Intent i1 =
-			Intent i = new Intent(getActivity(), WriteBlogPostActivity.class);
+						new Intent(getActivity(), WriteBlogPostActivity.class);
-			i.putExtra(GROUP_ID, personalBlog.getId().getBytes());
+				i1.putExtra(GROUP_ID, personalBlog.getId().getBytes());
-			startActivity(i);
+				startActivityForResult(i1, REQUEST_WRITE_BLOG_POST);
-			return true;
+				return true;
-		} else if (itemId == R.id.action_rss_feeds_import) {
+			case R.id.action_rss_feeds_import:
-			Intent i = new Intent(getActivity(), RssFeedImportActivity.class);
+				Intent i2 =
-			startActivity(i);
+						new Intent(getActivity(), RssFeedImportActivity.class);
-			return true;
+				startActivity(i2);
-		} else if (itemId == R.id.action_rss_feeds_manage) {
+				return true;
-			Blog personalBlog = viewModel.getPersonalBlog().getValue();
+			case R.id.action_rss_feeds_manage:
-			if (personalBlog == null) return false;
+				Intent i3 =
-			Intent i = new Intent(getActivity(), RssFeedManageActivity.class);
+						new Intent(getActivity(), RssFeedManageActivity.class);
-			i.putExtra(GROUP_ID, personalBlog.getId().getBytes());
+				i3.putExtra(GROUP_ID, personalBlog.getId().getBytes());
-			startActivity(i);
+				startActivity(i3);
-			return true;
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
 		}
-		return super.onOptionsItemSelected(item);
+	}
+
+	@Override
+	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
+		feedController.loadBlogPost(header,
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
+						this) {
+					@Override
+					public void onResultUi(BlogPostItem post) {
+						adapter.incrementRevision();
+						adapter.add(post);
+						if (local) {
+							showSnackBar(R.string.blogs_blog_post_created);
+						} else {
+							showSnackBar(R.string.blogs_blog_post_received);
+						}
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				}
+		);
 	}
 
 	@Override
 	public void onBlogPostClick(BlogPostItem post) {
-		Intent i = getBlogActivityIntent(post.getGroupId());
+		FeedPostFragment f =
-		i.putExtra(POST_ID, post.getId().getBytes());
+				FeedPostFragment.newInstance(post.getGroupId(), post.getId());
-		requireContext().startActivity(i);
+		showNextFragment(f);
 	}
 
 	@Override
 	public void onAuthorClick(BlogPostItem post) {
-		Intent i = getBlogActivityIntent(post.getGroupId());
+		Intent i = new Intent(getContext(), BlogActivity.class);
-		requireContext().startActivity(i);
+		i.putExtra(GROUP_ID, post.getGroupId().getBytes());
-	}
+		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-
+		getContext().startActivity(i);
-	@Override
-	public void onLinkClick(String url) {
-		LinkDialogFragment f = LinkDialogFragment.newInstance(url);
-		f.show(getParentFragmentManager(), f.getUniqueTag());
 	}
 
 	@Override
@@ -170,13 +268,6 @@ public class FeedFragment extends BaseFragment
 		return TAG;
 	}
 
-	private Intent getBlogActivityIntent(GroupId groupId) {
-		Intent i = new Intent(requireContext(), BlogActivity.class);
-		i.putExtra(GROUP_ID, groupId.getBytes());
-		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-		return i;
-	}
-
 	private void showSnackBar(int stringRes) {
 		int firstVisible =
 				layoutManager.findFirstCompletelyVisibleItemPosition();
@@ -192,4 +283,14 @@ public class FeedFragment extends BaseFragment
 		sb.make(list, stringRes, LENGTH_LONG).show();
 	}
 
+	@Override
+	public void onBlogAdded() {
+		loadBlogPosts(false);
+	}
+
+	@Override
+	public void onBlogRemoved() {
+		loadBlogPosts(true);
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedPostFragment.java

@@ -0,0 +1,87 @@
+package org.briarproject.briar.android.blog;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+
+import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
+
+@UiThread
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class FeedPostFragment extends BasePostFragment {
+
+	private static final String TAG = FeedPostFragment.class.getName();
+
+	private GroupId blogId;
+
+	@Inject
+	FeedController feedController;
+
+	static FeedPostFragment newInstance(GroupId blogId, MessageId postId) {
+		FeedPostFragment f = new FeedPostFragment();
+
+		Bundle bundle = new Bundle();
+		bundle.putByteArray(GROUP_ID, blogId.getBytes());
+		bundle.putByteArray(POST_ID, postId.getBytes());
+
+		f.setArguments(bundle);
+		return f;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		Bundle args = requireArguments();
+		byte[] b = args.getByteArray(GROUP_ID);
+		if (b == null) throw new IllegalStateException("No group ID in args");
+		blogId = new GroupId(b);
+
+		return super.onCreateView(inflater, container, savedInstanceState);
+	}
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		feedController.loadBlogPost(blogId, postId,
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
+						this) {
+					@Override
+					public void onResultUi(BlogPostItem post) {
+						onBlogPostLoaded(post);
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedViewModel.java

@@ -1,133 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import android.app.Application;
-
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
-import org.briarproject.bramble.api.db.TransactionManager;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
-import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.briar.android.viewmodel.LiveResult;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.blog.Blog;
-import org.briarproject.briar.api.blog.BlogManager;
-import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.inject.Inject;
-
-import androidx.annotation.UiThread;
-import androidx.lifecycle.LiveData;
-import androidx.lifecycle.MutableLiveData;
-
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.api.blog.BlogManager.CLIENT_ID;
-
-@NotNullByDefault
-class FeedViewModel extends BaseViewModel {
-
-	private static final Logger LOG = getLogger(FeedViewModel.class.getName());
-
-	private final MutableLiveData<Blog> personalBlog = new MutableLiveData<>();
-
-	@Inject
-	FeedViewModel(Application application,
-			@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager,
-			TransactionManager db,
-			AndroidExecutor androidExecutor,
-			EventBus eventBus,
-			IdentityManager identityManager,
-			AndroidNotificationManager notificationManager,
-			BlogManager blogManager) {
-		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
-				eventBus, identityManager, notificationManager, blogManager);
-		loadPersonalBlog();
-		loadAllBlogPosts();
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof BlogPostAddedEvent) {
-			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
-			LOG.info("Blog post added");
-			onBlogPostAdded(b.getHeader(), b.isLocal());
-		} else if (e instanceof GroupRemovedEvent) {
-			GroupRemovedEvent g = (GroupRemovedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Blog removed");
-				onBlogRemoved(g.getGroup().getId());
-			}
-		}
-	}
-
-	void blockAndClearAllBlogPostNotifications() {
-		notificationManager.blockAllBlogPostNotifications();
-		notificationManager.clearAllBlogPostNotifications();
-	}
-
-	void unblockAllBlogPostNotifications() {
-		notificationManager.unblockAllBlogPostNotifications();
-	}
-
-	private void loadPersonalBlog() {
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				Author a = identityManager.getLocalAuthor();
-				Blog b = blogManager.getPersonalBlog(a);
-				logDuration(LOG, "Loading personal blog", start);
-				personalBlog.postValue(b);
-			} catch (DbException e) {
-				handleException(e);
-			}
-		});
-	}
-
-	LiveData<Blog> getPersonalBlog() {
-		return personalBlog;
-	}
-
-	private void loadAllBlogPosts() {
-		loadFromDb(this::loadAllBlogPosts, blogPosts::setValue);
-	}
-
-	@DatabaseExecutor
-	private ListUpdate loadAllBlogPosts(Transaction txn)
-			throws DbException {
-		long start = now();
-		List<BlogPostItem> posts = new ArrayList<>();
-		for (GroupId g : blogManager.getBlogIds(txn)) {
-			posts.addAll(loadBlogPosts(txn, g));
-		}
-		Collections.sort(posts);
-		logDuration(LOG, "Loading all posts", start);
-		return new ListUpdate(null, posts);
-	}
-
-	@UiThread
-	private void onBlogRemoved(GroupId g) {
-		List<BlogPostItem> items = removeListItems(getBlogPostItems(), item ->
-				item.getGroupId().equals(g)
-		);
-		if (items != null) {
-			blogPosts.setValue(new LiveResult<>(new ListUpdate(null, items)));
-		}
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/OnBlogPostClickListener.java

@@ -5,6 +5,4 @@ interface OnBlogPostClickListener {
 	void onBlogPostClick(BlogPostItem post);
 
 	void onAuthorClick(BlogPostItem post);
-
-	void onLinkClick(String url);
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogActivity.java

@@ -11,7 +11,7 @@ import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
+import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
 
 public class ReblogActivity extends BriarActivity implements
 		BaseFragmentListener {
@@ -39,11 +39,13 @@ public class ReblogActivity extends BriarActivity implements
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		if (item.getItemId() == android.R.id.home) {
+		switch (item.getItemId()) {
-			onBackPressed();
+			case android.R.id.home:
-			return true;
+				onBackPressed();
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
 		}
-		return super.onOptionsItemSelected(item);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogFragment.java

@@ -7,17 +7,20 @@ import android.view.ViewGroup;
 import android.widget.ProgressBar;
 import android.widget.ScrollView;
 
+import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.controller.handler.UiExceptionHandler;
+import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.view.TextInputView;
 import org.briarproject.briar.android.view.TextSendController;
 import org.briarproject.briar.android.view.TextSendController.SendListener;
-import org.briarproject.briar.android.widget.LinkDialogFragment;
+import org.briarproject.briar.android.view.TextSendController.SendState;
 import org.briarproject.briar.api.attachment.AttachmentHeader;
 
 import java.util.List;
@@ -25,7 +28,8 @@ import java.util.List;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import androidx.lifecycle.ViewModelProvider;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
 
 import static android.view.View.FOCUS_DOWN;
 import static android.view.View.GONE;
@@ -33,7 +37,8 @@ import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.blog.BlogPostFragment.POST_ID;
+import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
+import static org.briarproject.briar.android.view.TextSendController.SendState.SENT;
 import static org.briarproject.briar.api.blog.BlogConstants.MAX_BLOG_POST_TEXT_LENGTH;
 
 @MethodsNotNullByDefault
@@ -42,13 +47,12 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 
 	public static final String TAG = ReblogFragment.class.getName();
 
-	@Inject
-	ViewModelProvider.Factory viewModelFactory;
-
-	private BlogViewModel viewModel;
 	private ViewHolder ui;
 	private BlogPostItem item;
 
+	@Inject
+	FeedController feedController;
+
 	static ReblogFragment newInstance(GroupId groupId, MessageId messageId) {
 		ReblogFragment f = new ReblogFragment();
 
@@ -68,8 +72,6 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
-				.get(BlogViewModel.class);
 	}
 
 	@Override
@@ -93,20 +95,30 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 		ui.input.setMaxTextLength(MAX_BLOG_POST_TEXT_LENGTH);
 		showProgressBar();
 
-		viewModel.loadBlogPost(blogId, postId).observe(getViewLifecycleOwner(),
+		feedController.loadBlogPost(blogId, postId,
-				result -> result.onError(this::handleException)
+				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						.onSuccess(this::bindViewHolder)
+						this) {
-		);
+					@Override
+					public void onResultUi(BlogPostItem result) {
+						item = result;
+						bindViewHolder();
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
 
 		return v;
 	}
 
-	private void bindViewHolder(BlogPostItem item) {
+	private void bindViewHolder() {
-		this.item = item;
+		if (item == null) return;
 
 		hideProgressBar();
 
-		ui.post.bindItem(this.item);
+		ui.post.bindItem(item);
 		ui.post.hideReblogButton();
 
 		ui.input.setReady(true);
@@ -114,11 +126,18 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text,
+	public LiveData<SendState> onSendClick(@Nullable String text,
-			List<AttachmentHeader> headers) {
+			List<AttachmentHeader> headers, long expectedAutoDeleteTimer) {
 		ui.input.hideSoftKeyboard();
-		viewModel.repeatPost(item, text);
+		feedController.repeatPost(item, text,
+				new UiExceptionHandler<DbException>(this) {
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleException(exception);
+					}
+				});
 		finish();
+		return new MutableLiveData<>(SENT);
 	}
 
 	private void showProgressBar() {
@@ -131,7 +150,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 		ui.input.setVisibility(VISIBLE);
 	}
 
-	private class ViewHolder implements OnBlogPostClickListener {
+	private class ViewHolder {
 
 		private final ScrollView scrollView;
 		private final ProgressBar progressBar;
@@ -142,25 +161,18 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 			scrollView = v.findViewById(R.id.scrollView);
 			progressBar = v.findViewById(R.id.progressBar);
 			post = new BlogPostViewHolder(v.findViewById(R.id.postLayout),
-					true, this, false);
+					true, new OnBlogPostClickListener() {
+				@Override
+				public void onBlogPostClick(BlogPostItem post) {
+					// do nothing
+				}
+
+				@Override
+				public void onAuthorClick(BlogPostItem post) {
+					// probably don't want to allow author clicks here
+				}
+			}, getFragmentManager());
 			input = v.findViewById(R.id.inputText);
 		}
-
-		@Override
-		public void onBlogPostClick(BlogPostItem post) {
-			// do nothing
-		}
-
-		@Override
-		public void onAuthorClick(BlogPostItem post) {
-			// probably don't want to allow author clicks here
-		}
-
-		@Override
-		public void onLinkClick(String url) {
-			LinkDialogFragment f = LinkDialogFragment.newInstance(url);
-			f.show(getParentFragmentManager(), f.getUniqueTag());
-		}
 	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/WriteBlogPostActivity.java

@@ -31,12 +31,16 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
 
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
+import static org.briarproject.briar.android.view.TextSendController.SendState;
+import static org.briarproject.briar.android.view.TextSendController.SendState.SENT;
 import static org.briarproject.briar.api.blog.BlogConstants.MAX_BLOG_POST_TEXT_LENGTH;
 
 @MethodsNotNullByDefault
@@ -112,8 +116,8 @@ public class WriteBlogPostActivity extends BriarActivity
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text,
+	public LiveData<SendState> onSendClick(@Nullable String text,
-			List<AttachmentHeader> headers) {
+			List<AttachmentHeader> headers, long expectedAutoDeleteTimer) {
 		if (isNullOrEmpty(text)) throw new AssertionError();
 
 		// hide publish button, show progress bar
@@ -122,6 +126,7 @@ public class WriteBlogPostActivity extends BriarActivity
 		progressBar.setVisibility(VISIBLE);
 
 		storePost(text);
+		return new MutableLiveData<>(SENT);
 	}
 
 	private void storePost(String text) {

briar-android/src/main/java/org/briarproject/briar/android/contact/BaseContactListAdapter.java

@@ -1,6 +1,7 @@
 package org.briarproject.briar.android.contact;
 
 import android.content.Context;
+import android.view.View;
 
 import org.briarproject.briar.android.util.BriarAdapter;
 
@@ -44,4 +45,8 @@ public abstract class BaseContactListAdapter<I extends ContactItem, VH extends C
 		return true;
 	}
 
+	public interface OnContactClickListener<I> {
+		void onItemClick(View view, I item);
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactItemViewHolder.java

@@ -7,6 +7,7 @@ import android.widget.TextView;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 
 import javax.annotation.Nullable;
 

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListAdapter.java

@@ -7,6 +7,7 @@ import android.view.ViewGroup;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.NullSafety;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 
 import androidx.recyclerview.widget.DiffUtil.ItemCallback;
 import androidx.recyclerview.widget.ListAdapter;
@@ -15,6 +16,9 @@ import androidx.recyclerview.widget.ListAdapter;
 public class ContactListAdapter extends
 		ListAdapter<ContactListItem, ContactListItemViewHolder> {
 
+	// TODO: using the click listener interface from BaseContactListAdapter on
+	// purpose here because it is entangled with ContactListItemViewHolder. At
+	// some point we probably want to change that.
 	protected final OnContactClickListener<ContactListItem> listener;
 
 	public ContactListAdapter(

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListFragment.java

@@ -15,6 +15,7 @@ import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 import org.briarproject.briar.android.contact.add.remote.AddContactActivity;
 import org.briarproject.briar.android.contact.add.remote.PendingContactListActivity;
 import org.briarproject.briar.android.conversation.ConversationActivity;
@@ -100,6 +101,8 @@ public class ContactListFragment extends BaseFragment
 				.observe(getViewLifecycleOwner(), result -> {
 					result.onError(this::handleException).onSuccess(items -> {
 						adapter.submitList(items);
+						// TODO remove when BriarRecyclerView was adapted
+						list.showData();
 					});
 				});
 		viewModel.getHasPendingContacts()

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListItemViewHolder.java

@@ -5,6 +5,7 @@ import android.widget.TextView;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 
 import java.util.Locale;
 

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListViewModel.java

@@ -3,41 +3,70 @@ package org.briarproject.briar.android.contact;
 import android.app.Application;
 
 import org.briarproject.bramble.api.connection.ConnectionRegistry;
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
+import org.briarproject.bramble.api.contact.event.ContactAddedEvent;
+import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.contact.event.PendingContactAddedEvent;
 import org.briarproject.bramble.api.contact.event.PendingContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
+import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
 import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+import org.briarproject.briar.android.viewmodel.LiveResult;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.avatar.event.AvatarUpdatedEvent;
+import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.conversation.ConversationManager;
+import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
+import org.briarproject.briar.api.identity.AuthorInfo;
 import org.briarproject.briar.api.identity.AuthorManager;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
+import androidx.arch.core.util.Function;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
 
 @NotNullByDefault
-class ContactListViewModel extends ContactsViewModel {
+class ContactListViewModel extends DbViewModel implements EventListener {
 
 	private static final Logger LOG =
 			getLogger(ContactListViewModel.class.getName());
 
+	private final ContactManager contactManager;
+	private final AuthorManager authorManager;
+	private final ConversationManager conversationManager;
+	private final ConnectionRegistry connectionRegistry;
+	private final EventBus eventBus;
 	private final AndroidNotificationManager notificationManager;
 
+	private final MutableLiveData<LiveResult<List<ContactListItem>>>
+			contactListItems = new MutableLiveData<>();
+
 	private final MutableLiveData<Boolean> hasPendingContacts =
 			new MutableLiveData<>();
 
@@ -50,25 +79,99 @@ class ContactListViewModel extends ContactsViewModel {
 			ConversationManager conversationManager,
 			ConnectionRegistry connectionRegistry, EventBus eventBus,
 			AndroidNotificationManager notificationManager) {
-		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
-				contactManager, authorManager, conversationManager,
+		this.contactManager = contactManager;
-				connectionRegistry, eventBus);
+		this.authorManager = authorManager;
+		this.conversationManager = conversationManager;
+		this.connectionRegistry = connectionRegistry;
+		this.eventBus = eventBus;
 		this.notificationManager = notificationManager;
+		this.eventBus.addListener(this);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
+	}
+
+	void loadContacts() {
+		loadList(this::loadContacts, contactListItems::setValue);
+	}
+
+	private List<ContactListItem> loadContacts(Transaction txn)
+			throws DbException {
+		long start = now();
+		List<ContactListItem> contacts = new ArrayList<>();
+		for (Contact c : contactManager.getContacts(txn)) {
+			ContactId id = c.getId();
+			AuthorInfo authorInfo = authorManager.getAuthorInfo(txn, c);
+			MessageTracker.GroupCount count =
+					conversationManager.getGroupCount(txn, id);
+			boolean connected = connectionRegistry.isConnected(c.getId());
+			contacts.add(new ContactListItem(c, authorInfo, connected, count));
+		}
+		Collections.sort(contacts);
+		logDuration(LOG, "Full load", start);
+		return contacts;
 	}
 
 	@Override
 	public void eventOccurred(Event e) {
-		super.eventOccurred(e);
+		if (e instanceof ContactAddedEvent) {
-		if (e instanceof PendingContactAddedEvent ||
+			LOG.info("Contact added, reloading");
+			loadContacts();
+		} else if (e instanceof ContactConnectedEvent) {
+			updateItem(((ContactConnectedEvent) e).getContactId(),
+					item -> new ContactListItem(item, true), false);
+		} else if (e instanceof ContactDisconnectedEvent) {
+			updateItem(((ContactDisconnectedEvent) e).getContactId(),
+					item -> new ContactListItem(item, false), false);
+		} else if (e instanceof ContactRemovedEvent) {
+			LOG.info("Contact removed, removing item");
+			removeItem(((ContactRemovedEvent) e).getContactId());
+		} else if (e instanceof ConversationMessageReceivedEvent) {
+			LOG.info("Conversation message received, updating item");
+			ConversationMessageReceivedEvent<?> p =
+					(ConversationMessageReceivedEvent<?>) e;
+			ConversationMessageHeader h = p.getMessageHeader();
+			updateItem(p.getContactId(), item -> new ContactListItem(item, h),
+					true);
+		} else if (e instanceof PendingContactAddedEvent ||
 				e instanceof PendingContactRemovedEvent) {
 			checkForPendingContacts();
+		} else if (e instanceof AvatarUpdatedEvent) {
+			AvatarUpdatedEvent a = (AvatarUpdatedEvent) e;
+			updateItem(a.getContactId(), item -> new ContactListItem(item,
+					a.getAttachmentHeader()), false);
 		}
 	}
 
+	LiveData<LiveResult<List<ContactListItem>>> getContactListItems() {
+		return contactListItems;
+	}
+
 	LiveData<Boolean> getHasPendingContacts() {
 		return hasPendingContacts;
 	}
 
+	private void updateItem(ContactId c,
+			Function<ContactListItem, ContactListItem> replacer, boolean sort) {
+		List<ContactListItem> list = updateListItems(contactListItems,
+				itemToTest -> itemToTest.getContact().getId().equals(c),
+				replacer);
+		if (list == null) return;
+		if (sort) Collections.sort(list);
+		contactListItems.setValue(new LiveResult<>(list));
+	}
+
+	private void removeItem(ContactId c) {
+		List<ContactListItem> list = removeListItems(contactListItems,
+				itemToTest -> itemToTest.getContact().getId().equals(c));
+		if (list == null) return;
+		contactListItems.setValue(new LiveResult<>(list));
+	}
+
 	void checkForPendingContacts() {
 		runOnDbThread(() -> {
 			try {

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactsViewModel.java

@@ -1,168 +0,0 @@
-package org.briarproject.briar.android.contact;
-
-import android.app.Application;
-
-import org.briarproject.bramble.api.connection.ConnectionRegistry;
-import org.briarproject.bramble.api.contact.Contact;
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.contact.ContactManager;
-import org.briarproject.bramble.api.contact.event.ContactAddedEvent;
-import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
-import org.briarproject.bramble.api.db.TransactionManager;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventListener;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
-import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
-import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.briar.android.viewmodel.DbViewModel;
-import org.briarproject.briar.android.viewmodel.LiveResult;
-import org.briarproject.briar.api.avatar.event.AvatarUpdatedEvent;
-import org.briarproject.briar.api.client.MessageTracker;
-import org.briarproject.briar.api.conversation.ConversationManager;
-import org.briarproject.briar.api.conversation.ConversationMessageHeader;
-import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
-import org.briarproject.briar.api.identity.AuthorInfo;
-import org.briarproject.briar.api.identity.AuthorManager;
-
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.inject.Inject;
-
-import androidx.annotation.UiThread;
-import androidx.arch.core.util.Function;
-import androidx.lifecycle.LiveData;
-import androidx.lifecycle.MutableLiveData;
-
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.now;
-
-@NotNullByDefault
-public class ContactsViewModel extends DbViewModel implements EventListener {
-
-	private static final Logger LOG =
-			getLogger(ContactsViewModel.class.getName());
-
-	protected final ContactManager contactManager;
-	private final AuthorManager authorManager;
-	private final ConversationManager conversationManager;
-	private final ConnectionRegistry connectionRegistry;
-	private final EventBus eventBus;
-
-	private final MutableLiveData<LiveResult<List<ContactListItem>>>
-			contactListItems = new MutableLiveData<>();
-
-	@Inject
-	public ContactsViewModel(Application application,
-			@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, TransactionManager db,
-			AndroidExecutor androidExecutor, ContactManager contactManager,
-			AuthorManager authorManager,
-			ConversationManager conversationManager,
-			ConnectionRegistry connectionRegistry, EventBus eventBus) {
-		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
-		this.contactManager = contactManager;
-		this.authorManager = authorManager;
-		this.conversationManager = conversationManager;
-		this.connectionRegistry = connectionRegistry;
-		this.eventBus = eventBus;
-		this.eventBus.addListener(this);
-	}
-
-	@Override
-	protected void onCleared() {
-		super.onCleared();
-		eventBus.removeListener(this);
-	}
-
-	protected void loadContacts() {
-		loadFromDb(this::loadContacts, contactListItems::setValue);
-	}
-
-	private List<ContactListItem> loadContacts(Transaction txn)
-			throws DbException {
-		long start = now();
-		List<ContactListItem> contacts = new ArrayList<>();
-		for (Contact c : contactManager.getContacts(txn)) {
-			ContactId id = c.getId();
-			if (!displayContact(id)) {
-				continue;
-			}
-			AuthorInfo authorInfo = authorManager.getAuthorInfo(txn, c);
-			MessageTracker.GroupCount count =
-					conversationManager.getGroupCount(txn, id);
-			boolean connected = connectionRegistry.isConnected(c.getId());
-			contacts.add(new ContactListItem(c, authorInfo, connected, count));
-		}
-		Collections.sort(contacts);
-		logDuration(LOG, "Full load", start);
-		return contacts;
-	}
-
-	/**
-	 * Override this method to display only a subset of contacts.
-	 */
-	protected boolean displayContact(ContactId contactId) {
-		return true;
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof ContactAddedEvent) {
-			LOG.info("Contact added, reloading");
-			loadContacts();
-		} else if (e instanceof ContactConnectedEvent) {
-			updateItem(((ContactConnectedEvent) e).getContactId(),
-					item -> new ContactListItem(item, true), false);
-		} else if (e instanceof ContactDisconnectedEvent) {
-			updateItem(((ContactDisconnectedEvent) e).getContactId(),
-					item -> new ContactListItem(item, false), false);
-		} else if (e instanceof ContactRemovedEvent) {
-			LOG.info("Contact removed, removing item");
-			removeItem(((ContactRemovedEvent) e).getContactId());
-		} else if (e instanceof ConversationMessageReceivedEvent) {
-			LOG.info("Conversation message received, updating item");
-			ConversationMessageReceivedEvent<?> p =
-					(ConversationMessageReceivedEvent<?>) e;
-			ConversationMessageHeader h = p.getMessageHeader();
-			updateItem(p.getContactId(), item -> new ContactListItem(item, h),
-					true);
-		} else if (e instanceof AvatarUpdatedEvent) {
-			AvatarUpdatedEvent a = (AvatarUpdatedEvent) e;
-			updateItem(a.getContactId(), item -> new ContactListItem(item,
-					a.getAttachmentHeader()), false);
-		}
-	}
-
-	public LiveData<LiveResult<List<ContactListItem>>> getContactListItems() {
-		return contactListItems;
-	}
-
-	@UiThread
-	private void updateItem(ContactId c,
-			Function<ContactListItem, ContactListItem> replacer, boolean sort) {
-		List<ContactListItem> list = updateListItems(getList(contactListItems),
-				itemToTest -> itemToTest.getContact().getId().equals(c),
-				replacer);
-		if (list == null) return;
-		if (sort) Collections.sort(list);
-		contactListItems.setValue(new LiveResult<>(list));
-	}
-
-	@UiThread
-	private void removeItem(ContactId c) {
-		removeAndUpdateListItems(contactListItems,
-				itemToTest -> itemToTest.getContact().getId().equals(c));
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/contact/LegacyContactListAdapter.java

@@ -0,0 +1,50 @@
+package org.briarproject.briar.android.contact;
+
+import android.content.Context;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.R;
+
+@NotNullByDefault
+public class LegacyContactListAdapter extends
+		BaseContactListAdapter<ContactListItem, ContactListItemViewHolder> {
+
+	public LegacyContactListAdapter(Context context,
+			OnContactClickListener<ContactListItem> listener) {
+		super(context, ContactListItem.class, listener);
+	}
+
+	@Override
+	public ContactListItemViewHolder onCreateViewHolder(ViewGroup viewGroup,
+			int i) {
+		View v = LayoutInflater.from(viewGroup.getContext()).inflate(
+				R.layout.list_item_contact, viewGroup, false);
+
+		return new ContactListItemViewHolder(v);
+	}
+
+	@Override
+	public boolean areContentsTheSame(ContactListItem c1, ContactListItem c2) {
+		// check for all properties that influence visual
+		// representation of contact
+		if (c1.isEmpty() != c2.isEmpty()) {
+			return false;
+		}
+		if (c1.getUnreadCount() != c2.getUnreadCount()) {
+			return false;
+		}
+		if (c1.getTimestamp() != c2.getTimestamp()) {
+			return false;
+		}
+		return c1.isConnected() == c2.isConnected();
+	}
+
+	@Override
+	public int compare(ContactListItem c1, ContactListItem c2) {
+		return Long.compare(c2.getTimestamp(), c1.getTimestamp());
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/OnContactClickListener.java

@@ -1,9 +0,0 @@
-package org.briarproject.briar.android.contact;
-
-import android.view.View;
-
-public interface OnContactClickListener<I> {
-
-	void onItemClick(View view, I item);
-
-}

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseContactSelectorAdapter.java

@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.android.contact.BaseContactListAdapter;
 import org.briarproject.briar.android.contact.ContactItemViewHolder;
-import org.briarproject.briar.android.contact.OnContactClickListener;
 
 import java.util.ArrayList;
 import java.util.Collection;

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseContactSelectorFragment.java

@@ -12,8 +12,8 @@ import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 import org.briarproject.briar.android.contact.ContactItemViewHolder;
-import org.briarproject.briar.android.contact.OnContactClickListener;
 import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.view.BriarRecyclerView;

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseSelectableContactHolder.java

@@ -6,8 +6,8 @@ import android.widget.TextView;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 import org.briarproject.briar.android.contact.ContactItemViewHolder;
-import org.briarproject.briar.android.contact.OnContactClickListener;
 
 import javax.annotation.Nullable;
 

briar-android/src/main/java/org/briarproject/briar/android/contactselection/ContactSelectorAdapter.java

@@ -7,7 +7,6 @@ import android.view.ViewGroup;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.OnContactClickListener;
 
 @NotNullByDefault
 class ContactSelectorAdapter extends

briar-android/src/main/java/org/briarproject/briar/android/contactselection/ContactSelectorFragment.java

@@ -8,7 +8,7 @@ import android.view.MenuItem;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.OnContactClickListener;
+import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault

briar-android/src/main/java/org/briarproject/briar/android/contactselection/SelectableContactHolder.java

@@ -3,7 +3,7 @@ package org.briarproject.briar.android.contactselection;
 import android.view.View;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.contact.OnContactClickListener;
+import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
 
 import javax.annotation.Nullable;
 

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingController.java

@@ -0,0 +1,77 @@
+package org.briarproject.briar.android.controller;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.Collection;
+
+import androidx.annotation.UiThread;
+
+@Deprecated
+@NotNullByDefault
+public interface SharingController {
+
+	/**
+	 * Sets the listener that is called when contacts go on or offline.
+	 */
+	@UiThread
+	void setSharingListener(SharingListener listener);
+
+	/**
+	 * Unsets the listener.
+	 */
+	@UiThread
+	void unsetSharingListener(SharingListener listener);
+
+	/**
+	 * Call this when your lifecycle starts,
+	 * so the listener will be called when information changes.
+	 */
+	@UiThread
+	void onStart();
+
+	/**
+	 * Call this when your lifecycle stops,
+	 * so that the controller knows it can stops listening to events.
+	 */
+	@UiThread
+	void onStop();
+
+	/**
+	 * Adds one contact to be tracked.
+	 */
+	@UiThread
+	void add(ContactId c);
+
+	/**
+	 * Adds a collection of contacts to be tracked.
+	 */
+	@UiThread
+	void addAll(Collection<ContactId> contacts);
+
+	/**
+	 * Call this when the contact identified by c is no longer sharing
+	 * the given group identified by GroupId g.
+	 */
+	@UiThread
+	void remove(ContactId c);
+
+	/**
+	 * Returns the number of online contacts.
+	 */
+	@UiThread
+	int getOnlineCount();
+
+	/**
+	 * Returns the total number of contacts that have been added.
+	 */
+	@UiThread
+	int getTotalCount();
+
+	interface SharingListener {
+
+		@UiThread
+		void onSharingInfoUpdated(int total, int online);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingControllerImpl.java

@@ -0,0 +1,109 @@
+package org.briarproject.briar.android.controller;
+
+import org.briarproject.bramble.api.connection.ConnectionRegistry;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
+import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+
+@Deprecated
+@NotNullByDefault
+public class SharingControllerImpl implements SharingController, EventListener {
+
+	private final EventBus eventBus;
+	private final ConnectionRegistry connectionRegistry;
+
+	// UI thread
+	private final Set<ContactId> contacts = new HashSet<>();
+
+	// UI thread
+	@Nullable
+	private SharingListener listener;
+
+	@Inject
+	SharingControllerImpl(EventBus eventBus,
+			ConnectionRegistry connectionRegistry) {
+		this.eventBus = eventBus;
+		this.connectionRegistry = connectionRegistry;
+	}
+
+	@Override
+	public void setSharingListener(SharingListener listener) {
+		this.listener = listener;
+	}
+
+	@Override
+	public void unsetSharingListener(SharingListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
+	@Override
+	public void onStart() {
+		eventBus.addListener(this);
+	}
+
+	@Override
+	public void onStop() {
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof ContactConnectedEvent) {
+			setConnected(((ContactConnectedEvent) e).getContactId());
+		} else if (e instanceof ContactDisconnectedEvent) {
+			setConnected(((ContactDisconnectedEvent) e).getContactId());
+		}
+	}
+
+	@UiThread
+	private void setConnected(ContactId c) {
+		if (listener == null) throw new IllegalStateException();
+		if (contacts.contains(c)) {
+			int online = getOnlineCount();
+			listener.onSharingInfoUpdated(contacts.size(), online);
+		}
+	}
+
+	@Override
+	public void addAll(Collection<ContactId> c) {
+		contacts.addAll(c);
+	}
+
+	@Override
+	public void add(ContactId c) {
+		contacts.add(c);
+	}
+
+	@Override
+	public void remove(ContactId c) {
+		contacts.remove(c);
+	}
+
+	@Override
+	public int getOnlineCount() {
+		int online = 0;
+		for (ContactId c : contacts) {
+			if (connectionRegistry.isConnected(c)) online++;
+		}
+		return online;
+	}
+
+	@Override
+	public int getTotalCount() {
+		return contacts.size();
+	}
+
+}

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

@@ -31,6 +31,8 @@ import static org.briarproject.briar.android.util.UiUtils.showSoftKeyboard;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
+// TODO: we can probably switch to androidx DialogFragment here but need to
+//  test this properly
 public class AliasDialogFragment extends AppCompatDialogFragment {
 
 	final static String TAG = AliasDialogFragment.class.getName();

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

@@ -50,6 +50,7 @@ import org.briarproject.briar.android.blog.BlogActivity;
 import org.briarproject.briar.android.conversation.ConversationVisitor.AttachmentCache;
 import org.briarproject.briar.android.conversation.ConversationVisitor.TextCache;
 import org.briarproject.briar.android.forum.ForumActivity;
+import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 import org.briarproject.briar.android.introduction.IntroductionActivity;
 import org.briarproject.briar.android.privategroup.conversation.GroupActivity;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
@@ -59,8 +60,10 @@ import org.briarproject.briar.android.view.TextAttachmentController;
 import org.briarproject.briar.android.view.TextAttachmentController.AttachmentListener;
 import org.briarproject.briar.android.view.TextInputView;
 import org.briarproject.briar.android.view.TextSendController;
+import org.briarproject.briar.android.view.TextSendController.SendState;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.attachment.AttachmentHeader;
+import org.briarproject.briar.api.autodelete.event.ConversationMessagesDeletedEvent;
 import org.briarproject.briar.api.blog.BlogSharingManager;
 import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.client.SessionId;
@@ -138,12 +141,14 @@ import static org.briarproject.briar.android.util.UiUtils.observeOnce;
 import static org.briarproject.briar.android.view.AuthorView.setAvatar;
 import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_ATTACHMENTS_PER_MESSAGE;
 import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_PRIVATE_MESSAGE_TEXT_LENGTH;
+import static org.briarproject.briar.api.messaging.PrivateMessageFormat.TEXT_IMAGES_AUTO_DELETE;
+import static org.briarproject.briar.api.messaging.PrivateMessageFormat.TEXT_ONLY;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class ConversationActivity extends BriarActivity
-		implements EventListener, ConversationListener, TextCache,
+		implements BaseFragmentListener, EventListener, ConversationListener,
-		AttachmentCache, AttachmentListener, ActionMode.Callback {
+		TextCache, AttachmentCache, AttachmentListener, ActionMode.Callback {
 
 	public static final String CONTACT_ID = "briar.CONTACT_ID";
 
@@ -268,15 +273,11 @@ public class ConversationActivity extends BriarActivity
 			ImagePreview imagePreview = findViewById(R.id.imagePreview);
 			sendController = new TextAttachmentController(textInputView,
 					imagePreview, this, viewModel);
-			viewModel.hasImageSupport().observe(this, new Observer<Boolean>() {
+			observeOnce(viewModel.getPrivateMessageFormat(), this, format -> {
-				@Override
+				if (format != TEXT_ONLY) {
-				public void onChanged(@Nullable Boolean hasSupport) {
+					// TODO: remove cast when removing feature flag
-					if (hasSupport != null && hasSupport) {
+					((TextAttachmentController) sendController)
-						// TODO: remove cast when removing feature flag
+							.setImagesSupported();
-						((TextAttachmentController) sendController)
-								.setImagesSupported();
-						viewModel.hasImageSupport().removeObserver(this);
-					}
 				}
 			});
 		} else {
@@ -286,6 +287,9 @@ public class ConversationActivity extends BriarActivity
 		textInputView.setMaxTextLength(MAX_PRIVATE_MESSAGE_TEXT_LENGTH);
 		textInputView.setReady(false);
 		textInputView.setOnKeyboardShownListener(this::scrollToBottom);
+
+		viewModel.getAutoDeleteTimer().observe(this, timer ->
+				sendController.setAutoDeleteTimer(timer));
 	}
 
 	private void scrollToBottom() {
@@ -369,6 +373,14 @@ public class ConversationActivity extends BriarActivity
 		// enable alias action if available
 		observeOnce(viewModel.getContactItem(), this, contact ->
 				menu.findItem(R.id.action_set_alias).setEnabled(true));
+		// Show auto-delete menu item if feature is enabled
+		if (featureFlags.shouldEnableDisappearingMessages()) {
+			MenuItem item = menu.findItem(R.id.action_conversation_settings);
+			item.setVisible(true);
+			// Enable menu item only if contact supports auto-delete
+			viewModel.getPrivateMessageFormat().observe(this, format ->
+					item.setEnabled(format == TEXT_IMAGES_AUTO_DELETE));
+		}
 
 		return super.onCreateOptionsMenu(menu);
 	}
@@ -390,6 +402,10 @@ public class ConversationActivity extends BriarActivity
 				AliasDialogFragment.newInstance().show(
 						getSupportFragmentManager(), AliasDialogFragment.TAG);
 				return true;
+			case R.id.action_conversation_settings:
+				if (contactId == null) return false;
+				onAutoDeleteTimerNoticeClicked();
+				return true;
 			case R.id.action_delete_all_messages:
 				askToDeleteAllMessages();
 				return true;
@@ -559,7 +575,7 @@ public class ConversationActivity extends BriarActivity
 							this::showImageOnboarding);
 				}
 				List<ConversationItem> items = createItems(headers);
-				adapter.addAll(items);
+				adapter.replaceAll(items);
 				list.showData();
 				if (layoutManagerState == null) {
 					scrollToBottom();
@@ -640,8 +656,8 @@ public class ConversationActivity extends BriarActivity
 				supportFinishAfterTransition();
 			}
 		} else if (e instanceof ConversationMessageReceivedEvent) {
-			ConversationMessageReceivedEvent p =
+			ConversationMessageReceivedEvent<?> p =
-					(ConversationMessageReceivedEvent) e;
+					(ConversationMessageReceivedEvent<?>) e;
 			if (p.getContactId().equals(contactId)) {
 				LOG.info("Message received, adding");
 				onNewConversationMessage(p.getMessageHeader());
@@ -658,6 +674,13 @@ public class ConversationActivity extends BriarActivity
 				LOG.info("Messages acked");
 				markMessages(m.getMessageIds(), true, true);
 			}
+		} else if (e instanceof ConversationMessagesDeletedEvent) {
+			ConversationMessagesDeletedEvent m =
+					(ConversationMessagesDeletedEvent) e;
+			if (m.getContactId().equals(contactId)) {
+				LOG.info("Messages auto-deleted");
+				onConversationMessagesDeleted(m.getMessageIds());
+			}
 		} else if (e instanceof ContactConnectedEvent) {
 			ContactConnectedEvent c = (ContactConnectedEvent) e;
 			if (c.getContactId().equals(contactId)) {
@@ -705,6 +728,13 @@ public class ConversationActivity extends BriarActivity
 		}
 	}
 
+	@UiThread
+	private void onConversationMessagesDeleted(
+			Collection<MessageId> messageIds) {
+		adapter.incrementRevision();
+		adapter.removeItems(messageIds);
+	}
+
 	@UiThread
 	private void markMessages(Collection<MessageId> messageIds, boolean sent,
 			boolean seen) {
@@ -735,20 +765,13 @@ public class ConversationActivity extends BriarActivity
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text,
+	public LiveData<SendState> onSendClick(@Nullable String text,
-			List<AttachmentHeader> attachmentHeaders) {
+			List<AttachmentHeader> attachmentHeaders,
+			long expectedAutoDeleteTimer) {
 		if (isNullOrEmpty(text) && attachmentHeaders.isEmpty())
 			throw new AssertionError();
-		long timestamp = System.currentTimeMillis();
+		return viewModel
-		timestamp = Math.max(timestamp, getMinTimestampForNewMessage());
+				.sendMessage(text, attachmentHeaders, expectedAutoDeleteTimer);
-		viewModel.sendMessage(text, attachmentHeaders, timestamp);
-		textInputView.clearText();
-	}
-
-	private long getMinTimestampForNewMessage() {
-		// Don't use an earlier timestamp than the newest message
-		ConversationItem item = adapter.getLastItem();
-		return item == null ? 0 : item.getTime() + 1;
 	}
 
 	private void onAddedPrivateMessage(@Nullable PrivateMessageHeader h) {
@@ -823,10 +846,6 @@ public class ConversationActivity extends BriarActivity
 			fails.add(getString(
 					R.string.dialog_message_not_deleted_ongoing_invitations));
 		}
-		if (result.hasNotFullyDownloaded()) {
-			fails.add(getString(
-					R.string.dialog_message_not_deleted_partly_downloaded));
-		}
 		// add problems the user can resolve
 		if (result.hasNotAllIntroductionSelected() &&
 				result.hasNotAllInvitationSelected()) {
@@ -958,13 +977,11 @@ public class ConversationActivity extends BriarActivity
 			adapter.notifyItemChanged(position, item);
 		}
 		runOnDbThread(() -> {
-			long timestamp = System.currentTimeMillis();
-			timestamp = Math.max(timestamp, getMinTimestampForNewMessage());
 			try {
 				switch (item.getRequestType()) {
 					case INTRODUCTION:
 						respondToIntroductionRequest(item.getSessionId(),
-								accept, timestamp);
+								accept);
 						break;
 					case FORUM:
 						respondToForumRequest(item.getSessionId(), accept);
@@ -1038,11 +1055,18 @@ public class ConversationActivity extends BriarActivity
 		ActivityCompat.startActivity(this, i, options.toBundle());
 	}
 
+	@Override
+	public void onAutoDeleteTimerNoticeClicked() {
+		ConversationSettingsDialog dialog =
+				ConversationSettingsDialog.newInstance(contactId);
+		dialog.show(getSupportFragmentManager(),
+				ConversationSettingsDialog.TAG);
+	}
+
 	@DatabaseExecutor
 	private void respondToIntroductionRequest(SessionId sessionId,
-			boolean accept, long time) throws DbException {
+			boolean accept) throws DbException {
-		introductionManager.respondToIntroduction(contactId, sessionId, time,
+		introductionManager.respondToIntroduction(contactId, sessionId, accept);
-				accept);
 	}
 
 	@DatabaseExecutor

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

@@ -13,20 +13,26 @@ import org.briarproject.briar.R;
 import org.briarproject.briar.android.util.BriarAdapter;
 import org.briarproject.briar.android.util.ItemReturningAdapter;
 
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
 import androidx.annotation.LayoutRes;
 import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
 import androidx.recyclerview.selection.SelectionTracker;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView.RecycledViewPool;
 
 import static androidx.recyclerview.widget.RecyclerView.NO_POSITION;
+import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
 
 @NotNullByDefault
 class ConversationAdapter
 		extends BriarAdapter<ConversationItem, ConversationItemViewHolder>
 		implements ItemReturningAdapter<ConversationItem> {
 
-	private ConversationListener listener;
+	private final ConversationListener listener;
 	private final RecycledViewPool imageViewPool;
 	private final ImageItemDecoration imageItemDecoration;
 	@Nullable
@@ -65,22 +71,20 @@ class ConversationAdapter
 			@LayoutRes int type) {
 		View v = LayoutInflater.from(viewGroup.getContext()).inflate(
 				type, viewGroup, false);
-		switch (type) {
+		if (type == R.layout.list_item_conversation_msg_in) {
-			case R.layout.list_item_conversation_msg_in:
+			return new ConversationMessageViewHolder(v, listener, true,
-				return new ConversationMessageViewHolder(v, listener, true,
+					imageViewPool, imageItemDecoration);
-						imageViewPool, imageItemDecoration);
+		} else if (type == R.layout.list_item_conversation_msg_out) {
-			case R.layout.list_item_conversation_msg_out:
+			return new ConversationMessageViewHolder(v, listener, false,
-				return new ConversationMessageViewHolder(v, listener, false,
+					imageViewPool, imageItemDecoration);
-						imageViewPool, imageItemDecoration);
+		} else if (type == R.layout.list_item_conversation_notice_in) {
-			case R.layout.list_item_conversation_notice_in:
+			return new ConversationNoticeViewHolder(v, listener, true);
-				return new ConversationNoticeViewHolder(v, listener, true);
+		} else if (type == R.layout.list_item_conversation_notice_out) {
-			case R.layout.list_item_conversation_notice_out:
+			return new ConversationNoticeViewHolder(v, listener, false);
-				return new ConversationNoticeViewHolder(v, listener, false);
+		} else if (type == R.layout.list_item_conversation_request) {
-			case R.layout.list_item_conversation_request:
+			return new ConversationRequestViewHolder(v, listener, true);
-				return new ConversationRequestViewHolder(v, listener, true);
-			default:
-				throw new IllegalArgumentException("Unknown ConversationItem");
 		}
+		throw new IllegalArgumentException("Unknown ConversationItem");
 	}
 
 	@Override
@@ -107,22 +111,65 @@ class ConversationAdapter
 		return c1.equals(c2);
 	}
 
+	@Override
+	public void add(ConversationItem item) {
+		items.beginBatchedUpdates();
+		items.add(item);
+		updateTimersInBatch();
+		items.endBatchedUpdates();
+	}
+
+	@Override
+	public void replaceAll(Collection<ConversationItem> itemsToReplace) {
+		items.beginBatchedUpdates();
+		// there can be items already in the adapter
+		// SortedList takes care of duplicates and detecting changed items
+		items.replaceAll(itemsToReplace);
+		updateTimersInBatch();
+		items.endBatchedUpdates();
+	}
+
+	@UiThread
+	void removeItems(Collection<MessageId> messageIds) {
+		// Collect all items to be deleted first
+		// and then delete them in one batched update.
+		// Deleting them right away would cause issues
+		// due to changing list positions.
+		List<ConversationItem> toRemove = new ArrayList<>(messageIds.size());
+		for (int i = 0; i < items.size(); i++) {
+			ConversationItem item = items.get(i);
+			if (messageIds.contains(item.getId())) toRemove.add(item);
+		}
+		items.beginBatchedUpdates();
+		for (ConversationItem item : toRemove) items.remove(item);
+		items.endBatchedUpdates();
+	}
+
+	private void updateTimersInBatch() {
+		long lastTimerIncoming = NO_AUTO_DELETE_TIMER;
+		long lastTimerOutgoing = NO_AUTO_DELETE_TIMER;
+		for (int i = 0; i < items.size(); i++) {
+			ConversationItem c = items.get(i);
+			boolean itemChanged;
+			boolean timerChanged;
+			if (c.isIncoming()) {
+				timerChanged = lastTimerIncoming != c.getAutoDeleteTimer();
+				lastTimerIncoming = c.getAutoDeleteTimer();
+			} else {
+				timerChanged = lastTimerOutgoing != c.getAutoDeleteTimer();
+				lastTimerOutgoing = c.getAutoDeleteTimer();
+			}
+			itemChanged = c.setTimerNoticeVisible(timerChanged);
+			if (itemChanged) items.updateItemAt(i, c);
+		}
+	}
+
 	void setSelectionTracker(SelectionTracker<String> tracker) {
 		this.tracker = tracker;
 	}
 
-	@Nullable
-	ConversationItem getLastItem() {
-		if (items.size() > 0) {
-			return items.get(items.size() - 1);
-		} else {
-			return null;
-		}
-	}
-
 	SparseArray<ConversationItem> getOutgoingMessages() {
 		SparseArray<ConversationItem> messages = new SparseArray<>();
-
 		for (int i = 0; i < items.size(); i++) {
 			ConversationItem item = items.get(i);
 			if (!item.isIncoming()) {