diff --git a/Documentation/access-control.txt b/Documentation/access-control.txt
index 3e75a53..7d531ff 100644
--- a/Documentation/access-control.txt
+++ b/Documentation/access-control.txt
@@ -97,7 +97,7 @@
 groups are created on Gerrit site initialization and unique UUIDs are assigned
 to those groups. These UUIDs are different on different Gerrit sites.
 
-Gerrit comes with two predefined groups:
+Gerrit comes with three predefined groups:
 
 * link:#administrators[Administrators]
 * link:#service_users[Service Users]
diff --git a/Documentation/dev-plugins.txt b/Documentation/dev-plugins.txt
index bcc96b4..4fa5e68 100644
--- a/Documentation/dev-plugins.txt
+++ b/Documentation/dev-plugins.txt
@@ -623,6 +623,105 @@
     .to(MyListener.class);
 ----
 
+Blocking inside onStop() is a good choice for QOS limits which are
+attempting to restrict total usage of resources as might be done to
+to prevent a server overload. In these cases, when a server's resources
+are being exhausted, it is important to throttle all `Tasks`, and blocking
+the current thread from being used by any Task makes sense. However,
+Task parking (see below) is more appropriate if it desirable to limit a
+specific resource usage in favor of other resources, such as when
+prioritization or fairness policies are desired.
+
+[[taskParker]]
+== TaskParkers
+
+It is possible to park `com.google.gerrit.server.git.WorkQueue$Task`s
+before they run without depriving other `Tasks` of a thread. Parking is
+particularly useful for (de-)prioritizing certain `Tasks` based on resource
+quotas without blocking `Tasks` not using those resources. For example,
+when there is a desire to limit how many commands a single user can run
+concurrently it is typically also desirable to not limit the total amount
+of concurrently running commands to the same limit. The Task parking
+mechanism is useful for such Task limiting scenarios.
+
+The `TaskParker` interface works well with a Semaphore's `tryAcquire()`
+method even when the Semaphore is unavailable. However, blocking should
+not be done with a `TaskParker` and if it is desired, such as when using a
+Semaphore's `acquire()` method, use a `TaskListener` interface instead.
+
+To make use of Task parking, implement a
+`com.google.gerrit.server.git.WorkQueue$TaskParker` and register the
+TaskParker (as a TaskListener) from a plugin like this:
+
+[source,java]
+----
+  public class MyParker implements TaskParker {
+    Semaphore semaphore = new Semaphore(3);
+
+    @Override
+    public boolean isReadyToStart(Task<?> task) {
+      try {
+        return semaphore.tryAcquire();
+      } catch (InterruptedException e) {
+        return false;
+      }
+    }
+
+    @Override
+    public void onNotReadyToStart(Task<?> task) {
+      semaphore.release();
+    }
+
+    @Override
+    public void onStart(Task<?> task) {}
+
+    @Override
+    public void onStop(Task<?> task) {
+      semaphore.release();
+    }
+  }
+
+  bind(TaskListener.class)
+      .annotatedWith(Exports.named("MyParker"))
+      .to(MyParker.class);
+----
+
+Before running a Task, the executor will query each `TaskParker` to see
+if the Task may be run by calling `isReadyToStart()`. If any `TaskParker`
+returns `false` from `isReadyToStart()`, then the Task will get parked
+and the executor will wait until another Task completes before
+attempting to run a parked task again.
+
+Since parked `Tasks` are not actually running and consuming resources,
+they generally should also not be contributing towards those resource
+quotas which caused the task to be parked. For this reason, once it is
+determined that a Task will be parked, the executor will call
+`onNotReadyToStart()` on every `TaskParker` that previously returned `true`
+from `isReadyToStart()`. This allows those TaskParkers to reduce their
+resource usage counts which they bumped up in `isReadyToStart()` with
+the expectation that the Task may run. Since the Task is not running and
+the resource is not being used, reducing the resource usage count allows
+other `Tasks` needing that resource to run while the Task is parked.
+
+Once a running Task completes, the executor will attempt to run
+parked `Tasks` (in the order in which they were parked) by again calling
+`isReadyToStart()` on the TaskParkers, even the TaskParkers which
+previously returned a `true` before the Task was parked. This is
+necessary because although a Task may not have exceeded a specific
+resource limit before it was parked, another Task may since have been
+allowed to run and its usage of that resource may now cause the parked
+task under evaluation to need to be throttled and parked again.
+
+Note, the reason that it is important to not block inside the
+`isReadyToStart()` method is to avoid delaying the executor from calling
+`onNotReadyToStart()` on other TaskParkers holding resources, as this
+would prevent them from freeing those resources. Also, just as it is
+important to later release any resources acquired within
+`isReadyToStart()` in `onStop()`, it is even more important to release
+those resources in `onNotReadyToStart()` since `isReadyToStart()` may
+be called many times per `TaskParker`, but `onStop()` will only ever be
+be called once.
+
 [[change-message-modifier]]
 == Change Message Modifier
 
diff --git a/Documentation/js_licenses.txt b/Documentation/js_licenses.txt
index 8b6049e..ab77d1b 100644
--- a/Documentation/js_licenses.txt
+++ b/Documentation/js_licenses.txt
@@ -1137,6 +1137,45 @@
 ----
 
 
+[[highlightjs-epp]]
+highlightjs-epp
+
+* highlightjs-epp
+
+[[highlightjs-epp_license]]
+----
+BSD 3-Clause License
+
+Copyright (c) 2024, highlight.js
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+----
+
+
 [[highlightjs-structured-text]]
 highlightjs-structured-text
 
diff --git a/Documentation/licenses.txt b/Documentation/licenses.txt
index 7e3fa9a..91b6227 100644
--- a/Documentation/licenses.txt
+++ b/Documentation/licenses.txt
@@ -4021,6 +4021,45 @@
 ----
 
 
+[[highlightjs-epp]]
+highlightjs-epp
+
+* highlightjs-epp
+
+[[highlightjs-epp_license]]
+----
+BSD 3-Clause License
+
+Copyright (c) 2024, highlight.js
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+----
+
+
 [[highlightjs-structured-text]]
 highlightjs-structured-text
 
diff --git a/Documentation/rest-api-accounts.txt b/Documentation/rest-api-accounts.txt
index d0c4553..384585f 100644
--- a/Documentation/rest-api-accounts.txt
+++ b/Documentation/rest-api-accounts.txt
@@ -1317,6 +1317,7 @@
     "work_in_progress_by_default": true,
     "allow_browser_notifications": true,
     "allow_suggest_code_while_commenting": true,
+    "allow_autocompleting_comments": true,
     "diff_page_sidebar": "plugin-foo",
     "default_base_for_merges": "FIRST_PARENT",
     "my": [
@@ -1372,6 +1373,7 @@
     "disable_token_highlighting": true,
     "allow_browser_notifications": false,
     "allow_suggest_code_while_commenting": false,
+    "allow_autocompleting_comments": false,
     "diff_page_sidebar": "NONE",
     "diff_view": "SIDE_BY_SIDE",
     "mute_common_path_prefixes": true,
@@ -2723,6 +2725,9 @@
 |`allow_suggest_code_while_commenting`  |not set if `false`|
 Whether to receive suggested code while writing comments. This feature needs
 a plugin implementation.
+|`allow_autocompleting_comments`  |not set if `false`|
+Whether to receive autocompletions while writing comments. This feature needs
+a plugin implementation.
 |`diff_page_sidebar`            |optional|
 String indicating which sidebar should be open on the diff page. Set to "NONE"
 if no sidebars should be open. Plugin-supplied sidebars will be prefixed with
@@ -2801,6 +2806,9 @@
 |`allow_suggest_code_while_commenting`  |not set if `false`|
 Whether to receive suggested code while writing comments. This feature needs
 a plugin implementation.
+|`allow_autocompleting_comments`  |not set if `false`|
+Whether to receive autocompletions while writing comments. This feature needs
+a plugin implementation.
 |`diff_page_sidebar`            |optional|
 String indicating which sidebar should be open on the diff page. Set to "NONE"
 if no sidebars should be open. Plugin-supplied sidebars will be prefixed with
diff --git a/Documentation/user-notify.txt b/Documentation/user-notify.txt
index f420fe7..2da3802 100644
--- a/Documentation/user-notify.txt
+++ b/Documentation/user-notify.txt
@@ -245,11 +245,11 @@
 comments had been posted in that notification using "Yes" or "No", for
 example `Gerrit-HasComments: Yes`.
 
-[[Gerrit-HasLabels]]Gerrit-HasLabels::
+[[Gerrit-Has-Labels]]Gerrit-Has-Labels::
 
 In comment emails, the has-labels footer states whether label votes had
 been posted in that notification using "Yes" or "No", for
-example `Gerrit-HasLabels: No`.
+example `Gerrit-Has-Labels: No`.
 
 [[Gerrit-Comment-In-Reply-To]]Gerrit-Comment-In-Reply-To::
 
diff --git a/java/com/google/gerrit/entities/Account.java b/java/com/google/gerrit/entities/Account.java
index efbac97..4b7694a 100644
--- a/java/com/google/gerrit/entities/Account.java
+++ b/java/com/google/gerrit/entities/Account.java
@@ -22,6 +22,7 @@
 import com.google.common.base.MoreObjects;
 import com.google.common.primitives.Ints;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.gerrit.common.ConvertibleToProto;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import java.time.Instant;
@@ -58,6 +59,7 @@
 
   /** Key local to Gerrit to identify a user. */
   @AutoValue
+  @ConvertibleToProto
   public abstract static class Id implements Comparable<Id> {
     /** Parse an Account.Id out of a string representation. */
     public static Optional<Id> tryParse(String str) {
diff --git a/java/com/google/gerrit/entities/Change.java b/java/com/google/gerrit/entities/Change.java
index fad3aa8..51585f3 100644
--- a/java/com/google/gerrit/entities/Change.java
+++ b/java/com/google/gerrit/entities/Change.java
@@ -18,6 +18,7 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.primitives.Ints;
+import com.google.gerrit.common.ConvertibleToProto;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.client.ChangeStatus;
 import com.google.gson.Gson;
@@ -104,6 +105,7 @@
 
   /** The numeric change ID */
   @AutoValue
+  @ConvertibleToProto
   public abstract static class Id {
     /**
      * Parse a Change.Id out of a string representation.
@@ -271,6 +273,7 @@
    * "Ixxxxxx...", and is stored in the Change-Id footer of a commit.
    */
   @AutoValue
+  @ConvertibleToProto
   public abstract static class Key {
     // TODO(dborowitz): This hardly seems worth it: why would someone pass a URL-encoded change key?
     // Ideally the standard key() factory method would enforce the format and throw IAE.
@@ -434,7 +437,7 @@
   private Id changeId;
 
   /** ServerId of the Gerrit instance that has created the change */
-  private String serverId;
+  @Nullable private String serverId;
 
   /** Globally assigned unique identifier of the change */
   private Key changeKey;
@@ -545,7 +548,8 @@
    * ServerId of the Gerrit instance that created the change. It could be null when the change is
    * not fetched from NoteDb but obtained through protobuf deserialisation.
    */
-  public @Nullable String getServerId() {
+  @Nullable
+  public String getServerId() {
     return serverId;
   }
 
@@ -607,6 +611,7 @@
     return originalSubject != null ? originalSubject : subject;
   }
 
+  @Nullable
   public String getOriginalSubjectOrNull() {
     return originalSubject;
   }
@@ -652,6 +657,7 @@
     originalSubject = null;
   }
 
+  @Nullable
   public String getSubmissionId() {
     return submissionId;
   }
@@ -684,6 +690,7 @@
     return isAbandoned() || isMerged();
   }
 
+  @Nullable
   public String getTopic() {
     return topic;
   }
@@ -720,10 +727,12 @@
     this.revertOf = revertOf;
   }
 
+  @Nullable
   public Id getRevertOf() {
     return this.revertOf;
   }
 
+  @Nullable
   public PatchSet.Id getCherryPickOf() {
     return cherryPickOf;
   }
diff --git a/java/com/google/gerrit/entities/ChangeMessage.java b/java/com/google/gerrit/entities/ChangeMessage.java
index dea070f..c8fc7d2 100644
--- a/java/com/google/gerrit/entities/ChangeMessage.java
+++ b/java/com/google/gerrit/entities/ChangeMessage.java
@@ -15,6 +15,7 @@
 package com.google.gerrit.entities;
 
 import com.google.auto.value.AutoValue;
+import com.google.gerrit.common.ConvertibleToProto;
 import com.google.gerrit.common.Nullable;
 import java.time.Instant;
 import java.util.Objects;
@@ -34,6 +35,7 @@
   }
 
   @AutoValue
+  @ConvertibleToProto
   public abstract static class Key {
     public abstract Change.Id changeId();
 
diff --git a/java/com/google/gerrit/entities/HumanComment.java b/java/com/google/gerrit/entities/HumanComment.java
index 1e48f11..325bd6c 100644
--- a/java/com/google/gerrit/entities/HumanComment.java
+++ b/java/com/google/gerrit/entities/HumanComment.java
@@ -14,6 +14,7 @@
 
 package com.google.gerrit.entities;
 
+import com.google.gerrit.common.ConvertibleToProto;
 import java.time.Instant;
 import java.util.Objects;
 
@@ -26,6 +27,7 @@
  *
  * <p>Consider updating {@link #getApproximateSize()} when adding/changing fields.
  */
+@ConvertibleToProto
 public class HumanComment extends Comment {
 
   public boolean unresolved;
diff --git a/java/com/google/gerrit/entities/LabelId.java b/java/com/google/gerrit/entities/LabelId.java
index 2426818..e3b3024 100644
--- a/java/com/google/gerrit/entities/LabelId.java
+++ b/java/com/google/gerrit/entities/LabelId.java
@@ -15,8 +15,10 @@
 package com.google.gerrit.entities;
 
 import com.google.auto.value.AutoValue;
+import com.google.gerrit.common.ConvertibleToProto;
 
 @AutoValue
+@ConvertibleToProto
 public abstract class LabelId {
   public static final String LEGACY_SUBMIT_NAME = "SUBM";
   public static final String CODE_REVIEW = "Code-Review";
diff --git a/java/com/google/gerrit/entities/PatchSet.java b/java/com/google/gerrit/entities/PatchSet.java
index e8759fa..6f71874 100644
--- a/java/com/google/gerrit/entities/PatchSet.java
+++ b/java/com/google/gerrit/entities/PatchSet.java
@@ -23,6 +23,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.primitives.Ints;
 import com.google.errorprone.annotations.InlineMe;
+import com.google.gerrit.common.ConvertibleToProto;
 import com.google.gerrit.common.Nullable;
 import java.time.Instant;
 import java.util.List;
@@ -31,6 +32,7 @@
 
 /** A single revision of a {@link Change}. */
 @AutoValue
+@ConvertibleToProto
 public abstract class PatchSet {
   /** Is the reference name a change reference? */
   public static boolean isChangeRef(String name) {
@@ -67,6 +69,7 @@
   }
 
   @AutoValue
+  @ConvertibleToProto
   public abstract static class Id implements Comparable<Id> {
     /** Parse a PatchSet.Id out of a string representation. */
     public static Id parse(String str) {
diff --git a/java/com/google/gerrit/entities/PatchSetApproval.java b/java/com/google/gerrit/entities/PatchSetApproval.java
index 608cf0d..f78167b 100644
--- a/java/com/google/gerrit/entities/PatchSetApproval.java
+++ b/java/com/google/gerrit/entities/PatchSetApproval.java
@@ -16,6 +16,7 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.primitives.Shorts;
+import com.google.gerrit.common.ConvertibleToProto;
 import java.time.Instant;
 import java.util.Optional;
 
@@ -27,6 +28,7 @@
   }
 
   @AutoValue
+  @ConvertibleToProto
   public abstract static class Key {
     public abstract PatchSet.Id patchSetId();
 
diff --git a/java/com/google/gerrit/entities/Project.java b/java/com/google/gerrit/entities/Project.java
index 9c2866c..7b02597 100644
--- a/java/com/google/gerrit/entities/Project.java
+++ b/java/com/google/gerrit/entities/Project.java
@@ -20,6 +20,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.Immutable;
+import com.google.gerrit.common.ConvertibleToProto;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.client.InheritableBoolean;
 import com.google.gerrit.extensions.client.ProjectState;
@@ -57,6 +58,7 @@
    * <p>This class is immutable and thread safe.
    */
   @Immutable
+  @ConvertibleToProto
   public static class NameKey implements Serializable, Comparable<NameKey> {
     private static final long serialVersionUID = 1L;
 
diff --git a/java/com/google/gerrit/entities/converter/AccountIdProtoConverter.java b/java/com/google/gerrit/entities/converter/AccountIdProtoConverter.java
index 1e846fb..6106090 100644
--- a/java/com/google/gerrit/entities/converter/AccountIdProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/AccountIdProtoConverter.java
@@ -20,7 +20,7 @@
 import com.google.protobuf.Parser;
 
 @Immutable
-public enum AccountIdProtoConverter implements ProtoConverter<Entities.Account_Id, Account.Id> {
+public enum AccountIdProtoConverter implements SafeProtoConverter<Entities.Account_Id, Account.Id> {
   INSTANCE;
 
   @Override
@@ -37,4 +37,14 @@
   public Parser<Entities.Account_Id> getParser() {
     return Entities.Account_Id.parser();
   }
+
+  @Override
+  public Class<Entities.Account_Id> getProtoClass() {
+    return Entities.Account_Id.class;
+  }
+
+  @Override
+  public Class<Account.Id> getEntityClass() {
+    return Account.Id.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/ChangeIdProtoConverter.java b/java/com/google/gerrit/entities/converter/ChangeIdProtoConverter.java
index 0d4ec70..909b4d3 100644
--- a/java/com/google/gerrit/entities/converter/ChangeIdProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/ChangeIdProtoConverter.java
@@ -17,10 +17,11 @@
 import com.google.errorprone.annotations.Immutable;
 import com.google.gerrit.entities.Change;
 import com.google.gerrit.proto.Entities;
+import com.google.gerrit.proto.Entities.Change_Id;
 import com.google.protobuf.Parser;
 
 @Immutable
-public enum ChangeIdProtoConverter implements ProtoConverter<Entities.Change_Id, Change.Id> {
+public enum ChangeIdProtoConverter implements SafeProtoConverter<Entities.Change_Id, Change.Id> {
   INSTANCE;
 
   @Override
@@ -37,4 +38,14 @@
   public Parser<Entities.Change_Id> getParser() {
     return Entities.Change_Id.parser();
   }
+
+  @Override
+  public Class<Change_Id> getProtoClass() {
+    return Change_Id.class;
+  }
+
+  @Override
+  public Class<Change.Id> getEntityClass() {
+    return Change.Id.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/ChangeKeyProtoConverter.java b/java/com/google/gerrit/entities/converter/ChangeKeyProtoConverter.java
index f3ccdfa..0620c70 100644
--- a/java/com/google/gerrit/entities/converter/ChangeKeyProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/ChangeKeyProtoConverter.java
@@ -17,10 +17,11 @@
 import com.google.errorprone.annotations.Immutable;
 import com.google.gerrit.entities.Change;
 import com.google.gerrit.proto.Entities;
+import com.google.gerrit.proto.Entities.Change_Key;
 import com.google.protobuf.Parser;
 
 @Immutable
-public enum ChangeKeyProtoConverter implements ProtoConverter<Entities.Change_Key, Change.Key> {
+public enum ChangeKeyProtoConverter implements SafeProtoConverter<Entities.Change_Key, Change.Key> {
   INSTANCE;
 
   @Override
@@ -37,4 +38,14 @@
   public Parser<Entities.Change_Key> getParser() {
     return Entities.Change_Key.parser();
   }
+
+  @Override
+  public Class<Change_Key> getProtoClass() {
+    return Change_Key.class;
+  }
+
+  @Override
+  public Class<Change.Key> getEntityClass() {
+    return Change.Key.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/ChangeMessageKeyProtoConverter.java b/java/com/google/gerrit/entities/converter/ChangeMessageKeyProtoConverter.java
index 3e93c5a..a76ab98 100644
--- a/java/com/google/gerrit/entities/converter/ChangeMessageKeyProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/ChangeMessageKeyProtoConverter.java
@@ -18,11 +18,12 @@
 import com.google.gerrit.entities.Change;
 import com.google.gerrit.entities.ChangeMessage;
 import com.google.gerrit.proto.Entities;
+import com.google.gerrit.proto.Entities.ChangeMessage_Key;
 import com.google.protobuf.Parser;
 
 @Immutable
 public enum ChangeMessageKeyProtoConverter
-    implements ProtoConverter<Entities.ChangeMessage_Key, ChangeMessage.Key> {
+    implements SafeProtoConverter<Entities.ChangeMessage_Key, ChangeMessage.Key> {
   INSTANCE;
 
   private final ProtoConverter<Entities.Change_Id, Change.Id> changeIdConverter =
@@ -45,4 +46,14 @@
   public Parser<Entities.ChangeMessage_Key> getParser() {
     return Entities.ChangeMessage_Key.parser();
   }
+
+  @Override
+  public Class<ChangeMessage_Key> getProtoClass() {
+    return ChangeMessage_Key.class;
+  }
+
+  @Override
+  public Class<ChangeMessage.Key> getEntityClass() {
+    return ChangeMessage.Key.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/HumanCommentProtoConverter.java b/java/com/google/gerrit/entities/converter/HumanCommentProtoConverter.java
index 6e8c907..316a042 100644
--- a/java/com/google/gerrit/entities/converter/HumanCommentProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/HumanCommentProtoConverter.java
@@ -35,7 +35,7 @@
  */
 @Immutable
 public enum HumanCommentProtoConverter
-    implements ProtoConverter<Entities.HumanComment, HumanComment> {
+    implements SafeProtoConverter<Entities.HumanComment, HumanComment> {
   INSTANCE;
 
   private final ProtoConverter<Entities.Account_Id, Account.Id> accountIdConverter =
@@ -142,4 +142,14 @@
   public Parser<Entities.HumanComment> getParser() {
     return Entities.HumanComment.parser();
   }
+
+  @Override
+  public Class<Entities.HumanComment> getProtoClass() {
+    return Entities.HumanComment.class;
+  }
+
+  @Override
+  public Class<HumanComment> getEntityClass() {
+    return HumanComment.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/LabelIdProtoConverter.java b/java/com/google/gerrit/entities/converter/LabelIdProtoConverter.java
index a1894ac..e6e1be7f 100644
--- a/java/com/google/gerrit/entities/converter/LabelIdProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/LabelIdProtoConverter.java
@@ -20,7 +20,7 @@
 import com.google.protobuf.Parser;
 
 @Immutable
-public enum LabelIdProtoConverter implements ProtoConverter<Entities.LabelId, LabelId> {
+public enum LabelIdProtoConverter implements SafeProtoConverter<Entities.LabelId, LabelId> {
   INSTANCE;
 
   @Override
@@ -37,4 +37,14 @@
   public Parser<Entities.LabelId> getParser() {
     return Entities.LabelId.parser();
   }
+
+  @Override
+  public Class<Entities.LabelId> getProtoClass() {
+    return Entities.LabelId.class;
+  }
+
+  @Override
+  public Class<LabelId> getEntityClass() {
+    return LabelId.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/NotifyInfoProtoConverter.java b/java/com/google/gerrit/entities/converter/NotifyInfoProtoConverter.java
index 201dd78..fc963df 100644
--- a/java/com/google/gerrit/entities/converter/NotifyInfoProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/NotifyInfoProtoConverter.java
@@ -26,7 +26,8 @@
  * com.google.gerrit.proto.Entities.NotifyInfo}.
  */
 @Immutable
-public enum NotifyInfoProtoConverter implements ProtoConverter<Entities.NotifyInfo, NotifyInfo> {
+public enum NotifyInfoProtoConverter
+    implements SafeProtoConverter<Entities.NotifyInfo, NotifyInfo> {
   INSTANCE;
 
   @Override
@@ -47,4 +48,14 @@
   public Parser<Entities.NotifyInfo> getParser() {
     return Entities.NotifyInfo.parser();
   }
+
+  @Override
+  public Class<Entities.NotifyInfo> getProtoClass() {
+    return Entities.NotifyInfo.class;
+  }
+
+  @Override
+  public Class<NotifyInfo> getEntityClass() {
+    return NotifyInfo.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/PatchSetApprovalKeyProtoConverter.java b/java/com/google/gerrit/entities/converter/PatchSetApprovalKeyProtoConverter.java
index c7d1714..3ea14e6 100644
--- a/java/com/google/gerrit/entities/converter/PatchSetApprovalKeyProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/PatchSetApprovalKeyProtoConverter.java
@@ -20,11 +20,12 @@
 import com.google.gerrit.entities.PatchSet;
 import com.google.gerrit.entities.PatchSetApproval;
 import com.google.gerrit.proto.Entities;
+import com.google.gerrit.proto.Entities.PatchSetApproval_Key;
 import com.google.protobuf.Parser;
 
 @Immutable
 public enum PatchSetApprovalKeyProtoConverter
-    implements ProtoConverter<Entities.PatchSetApproval_Key, PatchSetApproval.Key> {
+    implements SafeProtoConverter<Entities.PatchSetApproval_Key, PatchSetApproval.Key> {
   INSTANCE;
 
   private final ProtoConverter<Entities.PatchSet_Id, PatchSet.Id> patchSetIdConverter =
@@ -55,4 +56,14 @@
   public Parser<Entities.PatchSetApproval_Key> getParser() {
     return Entities.PatchSetApproval_Key.parser();
   }
+
+  @Override
+  public Class<PatchSetApproval_Key> getProtoClass() {
+    return PatchSetApproval_Key.class;
+  }
+
+  @Override
+  public Class<PatchSetApproval.Key> getEntityClass() {
+    return PatchSetApproval.Key.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/PatchSetIdProtoConverter.java b/java/com/google/gerrit/entities/converter/PatchSetIdProtoConverter.java
index 60c13f1..f6671cf 100644
--- a/java/com/google/gerrit/entities/converter/PatchSetIdProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/PatchSetIdProtoConverter.java
@@ -18,10 +18,12 @@
 import com.google.gerrit.entities.Change;
 import com.google.gerrit.entities.PatchSet;
 import com.google.gerrit.proto.Entities;
+import com.google.gerrit.proto.Entities.PatchSet_Id;
 import com.google.protobuf.Parser;
 
 @Immutable
-public enum PatchSetIdProtoConverter implements ProtoConverter<Entities.PatchSet_Id, PatchSet.Id> {
+public enum PatchSetIdProtoConverter
+    implements SafeProtoConverter<Entities.PatchSet_Id, PatchSet.Id> {
   INSTANCE;
 
   private final ProtoConverter<Entities.Change_Id, Change.Id> changeIdConverter =
@@ -44,4 +46,14 @@
   public Parser<Entities.PatchSet_Id> getParser() {
     return Entities.PatchSet_Id.parser();
   }
+
+  @Override
+  public Class<PatchSet_Id> getProtoClass() {
+    return PatchSet_Id.class;
+  }
+
+  @Override
+  public Class<PatchSet.Id> getEntityClass() {
+    return PatchSet.Id.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/PatchSetProtoConverter.java b/java/com/google/gerrit/entities/converter/PatchSetProtoConverter.java
index 196deca..22985d9 100644
--- a/java/com/google/gerrit/entities/converter/PatchSetProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/PatchSetProtoConverter.java
@@ -24,7 +24,7 @@
 import org.eclipse.jgit.lib.ObjectId;
 
 @Immutable
-public enum PatchSetProtoConverter implements ProtoConverter<Entities.PatchSet, PatchSet> {
+public enum PatchSetProtoConverter implements SafeProtoConverter<Entities.PatchSet, PatchSet> {
   INSTANCE;
 
   private final ProtoConverter<Entities.PatchSet_Id, PatchSet.Id> patchSetIdConverter =
@@ -103,4 +103,14 @@
   public Parser<Entities.PatchSet> getParser() {
     return Entities.PatchSet.parser();
   }
+
+  @Override
+  public Class<Entities.PatchSet> getProtoClass() {
+    return Entities.PatchSet.class;
+  }
+
+  @Override
+  public Class<PatchSet> getEntityClass() {
+    return PatchSet.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/ProjectNameKeyProtoConverter.java b/java/com/google/gerrit/entities/converter/ProjectNameKeyProtoConverter.java
index 6bb0f79..320b8fc 100644
--- a/java/com/google/gerrit/entities/converter/ProjectNameKeyProtoConverter.java
+++ b/java/com/google/gerrit/entities/converter/ProjectNameKeyProtoConverter.java
@@ -16,12 +16,14 @@
 
 import com.google.errorprone.annotations.Immutable;
 import com.google.gerrit.entities.Project;
+import com.google.gerrit.entities.Project.NameKey;
 import com.google.gerrit.proto.Entities;
+import com.google.gerrit.proto.Entities.Project_NameKey;
 import com.google.protobuf.Parser;
 
 @Immutable
 public enum ProjectNameKeyProtoConverter
-    implements ProtoConverter<Entities.Project_NameKey, Project.NameKey> {
+    implements SafeProtoConverter<Entities.Project_NameKey, Project.NameKey> {
   INSTANCE;
 
   @Override
@@ -38,4 +40,14 @@
   public Parser<Entities.Project_NameKey> getParser() {
     return Entities.Project_NameKey.parser();
   }
+
+  @Override
+  public Class<Project_NameKey> getProtoClass() {
+    return Project_NameKey.class;
+  }
+
+  @Override
+  public Class<NameKey> getEntityClass() {
+    return NameKey.class;
+  }
 }
diff --git a/java/com/google/gerrit/entities/converter/SafeProtoConverter.java b/java/com/google/gerrit/entities/converter/SafeProtoConverter.java
new file mode 100644
index 0000000..f4a66a0
--- /dev/null
+++ b/java/com/google/gerrit/entities/converter/SafeProtoConverter.java
@@ -0,0 +1,29 @@
+package com.google.gerrit.entities.converter;
+
+import com.google.errorprone.annotations.Immutable;
+import com.google.gerrit.common.ConvertibleToProto;
+import com.google.protobuf.Message;
+
+/**
+ * An extension to {@link ProtoConverter} that enforces the Entity class and the Proto class to stay
+ * in sync. The enforcement is done by {@link SafeProtoConverterTest}.
+ *
+ * <p>Requirements:
+ *
+ * <ul>
+ *   <li>Implementing classes must be enums with a single value. Please prefer descriptive enum and
+ *       instance names, such as {@code MyTypeConverter::MY_TYPE_CONVERTER}.
+ *   <li>The Java Entity class must be annotated with {@link ConvertibleToProto}.
+ * </ul>
+ *
+ * <p>All safe converters are tested using {@link SafeProtoConverterTest}. Therefore, unless your
+ * Entity class has a {@code defaults()} method, or other methods besides simple getters and
+ * setters, there is no need to explicitly test your safe converter.
+ */
+@Immutable
+public interface SafeProtoConverter<P extends Message, C> extends ProtoConverter<P, C> {
+
+  Class<P> getProtoClass();
+
+  Class<C> getEntityClass();
+}
diff --git a/java/com/google/gerrit/extensions/api/changes/NotifyInfo.java b/java/com/google/gerrit/extensions/api/changes/NotifyInfo.java
index dd29635..21bf886 100644
--- a/java/com/google/gerrit/extensions/api/changes/NotifyInfo.java
+++ b/java/com/google/gerrit/extensions/api/changes/NotifyInfo.java
@@ -15,10 +15,12 @@
 package com.google.gerrit.extensions.api.changes;
 
 import com.google.common.base.MoreObjects;
+import com.google.gerrit.common.ConvertibleToProto;
 import java.util.List;
 import java.util.Objects;
 
 /** Detailed information about who should be notified about an update. */
+@ConvertibleToProto
 public class NotifyInfo {
   public List<String> accounts;
 
diff --git a/java/com/google/gerrit/extensions/client/DiffPreferencesInfo.java b/java/com/google/gerrit/extensions/client/DiffPreferencesInfo.java
index 109afd6..ad494cb 100644
--- a/java/com/google/gerrit/extensions/client/DiffPreferencesInfo.java
+++ b/java/com/google/gerrit/extensions/client/DiffPreferencesInfo.java
@@ -15,8 +15,10 @@
 package com.google.gerrit.extensions.client;
 
 import com.google.common.base.MoreObjects;
+import com.google.gerrit.common.ConvertibleToProto;
 import java.util.Objects;
 
+@ConvertibleToProto
 public class DiffPreferencesInfo {
 
   /** Default number of lines of context. */
diff --git a/java/com/google/gerrit/extensions/client/EditPreferencesInfo.java b/java/com/google/gerrit/extensions/client/EditPreferencesInfo.java
index 0a3ec0a..5da211e 100644
--- a/java/com/google/gerrit/extensions/client/EditPreferencesInfo.java
+++ b/java/com/google/gerrit/extensions/client/EditPreferencesInfo.java
@@ -15,9 +15,11 @@
 package com.google.gerrit.extensions.client;
 
 import com.google.common.base.MoreObjects;
+import com.google.gerrit.common.ConvertibleToProto;
 import java.util.Objects;
 
 /* This class is stored in Git config file. */
+@ConvertibleToProto
 public class EditPreferencesInfo {
   public Integer tabSize;
   public Integer lineLength;
diff --git a/java/com/google/gerrit/extensions/client/GeneralPreferencesInfo.java b/java/com/google/gerrit/extensions/client/GeneralPreferencesInfo.java
index 1ed9793..44fc4d5 100644
--- a/java/com/google/gerrit/extensions/client/GeneralPreferencesInfo.java
+++ b/java/com/google/gerrit/extensions/client/GeneralPreferencesInfo.java
@@ -15,10 +15,12 @@
 package com.google.gerrit.extensions.client;
 
 import com.google.common.base.MoreObjects;
+import com.google.gerrit.common.ConvertibleToProto;
 import java.util.List;
 import java.util.Objects;
 
 /** Preferences about a single user. */
+@ConvertibleToProto
 public class GeneralPreferencesInfo {
 
   /** Default number of items to display per page. */
@@ -143,6 +145,8 @@
   public List<String> changeTable;
   public Boolean allowBrowserNotifications;
   public Boolean allowSuggestCodeWhileCommenting;
+  public Boolean allowAutocompletingComments;
+
   /**
    * The sidebar section that the user prefers to have open on the diff page, or "NONE" if all
    * sidebars should be closed.
@@ -214,6 +218,9 @@
         && Objects.equals(this.my, other.my)
         && Objects.equals(this.changeTable, other.changeTable)
         && Objects.equals(this.allowBrowserNotifications, other.allowBrowserNotifications)
+        && Objects.equals(
+            this.allowSuggestCodeWhileCommenting, other.allowSuggestCodeWhileCommenting)
+        && Objects.equals(this.allowAutocompletingComments, other.allowAutocompletingComments)
         && Objects.equals(this.diffPageSidebar, other.diffPageSidebar);
   }
 
@@ -242,6 +249,8 @@
         my,
         changeTable,
         allowBrowserNotifications,
+        allowSuggestCodeWhileCommenting,
+        allowAutocompletingComments,
         diffPageSidebar);
   }
 
@@ -270,6 +279,8 @@
         .add("my", my)
         .add("changeTable", changeTable)
         .add("allowBrowserNotifications", allowBrowserNotifications)
+        .add("allowSuggestCodeWhileCommenting", allowSuggestCodeWhileCommenting)
+        .add("allowAutocompletingComments", allowAutocompletingComments)
         .add("diffPageSidebar", diffPageSidebar)
         .toString();
   }
@@ -296,8 +307,9 @@
     p.disableTokenHighlighting = false;
     p.workInProgressByDefault = false;
     p.allowBrowserNotifications = true;
-    p.diffPageSidebar = "NONE";
     p.allowSuggestCodeWhileCommenting = true;
+    p.allowAutocompletingComments = true;
+    p.diffPageSidebar = "NONE";
     return p;
   }
 }
diff --git a/java/com/google/gerrit/server/account/AccountsUpdate.java b/java/com/google/gerrit/server/account/AccountsUpdate.java
index 5951a73..45ff128 100644
--- a/java/com/google/gerrit/server/account/AccountsUpdate.java
+++ b/java/com/google/gerrit/server/account/AccountsUpdate.java
@@ -20,6 +20,8 @@
 import static java.lang.annotation.ElementType.PARAMETER;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;
 
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.gerrit.entities.Account;
@@ -97,6 +99,14 @@
       this.accountId = accountId;
       this.configureDeltaFromState = configureDeltaFromState;
     }
+
+    @Override
+    public String toString() {
+      return MoreObjects.toStringHelper(this)
+          .add("message", message)
+          .add("accountId", accountId)
+          .toString();
+    }
   }
 
   /**
@@ -145,7 +155,7 @@
    * would only contain the account ID).
    */
   @CanIgnoreReturnValue
-  public AccountState insert(
+  public final AccountState insert(
       String message, Account.Id accountId, Consumer<AccountDelta.Builder> init)
       throws IOException, ConfigInvalidException {
     return insert(message, accountId, AccountsUpdate.fromConsumer(init));
@@ -171,7 +181,7 @@
    * instead, i.e. the update does not depend on the current account state.
    */
   @CanIgnoreReturnValue
-  public Optional<AccountState> update(
+  public final Optional<AccountState> update(
       String message, Account.Id accountId, Consumer<AccountDelta.Builder> update)
       throws IOException, ConfigInvalidException {
     return update(message, accountId, AccountsUpdate.fromConsumer(update));
@@ -193,7 +203,7 @@
    * @throws ConfigInvalidException if any of the account fields has an invalid value
    */
   @CanIgnoreReturnValue
-  public Optional<AccountState> update(
+  public final Optional<AccountState> update(
       String message, Account.Id accountId, ConfigureDeltaFromState configureDeltaFromState)
       throws IOException, ConfigInvalidException {
     return updateBatch(
@@ -212,7 +222,7 @@
    * together have this property) will always prevent the entire batch from being executed.
    */
   @CanIgnoreReturnValue
-  public ImmutableList<Optional<AccountState>> updateBatch(List<UpdateArguments> updates)
+  public final ImmutableList<Optional<AccountState>> updateBatch(List<UpdateArguments> updates)
       throws IOException, ConfigInvalidException {
     checkArgument(
         updates.stream().map(u -> u.accountId.get()).distinct().count() == updates.size(),
@@ -231,7 +241,8 @@
   public abstract void delete(String message, Account.Id accountId)
       throws IOException, ConfigInvalidException;
 
-  protected abstract ImmutableList<Optional<AccountState>> executeUpdates(
+  @VisibleForTesting // productionVisibility: protected
+  public abstract ImmutableList<Optional<AccountState>> executeUpdates(
       List<UpdateArguments> updates) throws ConfigInvalidException, IOException;
 
   private static PersonIdent createPersonIdent(
diff --git a/java/com/google/gerrit/server/account/storage/notedb/AccountsUpdateNoteDbImpl.java b/java/com/google/gerrit/server/account/storage/notedb/AccountsUpdateNoteDbImpl.java
index ad3681d..27a43ba 100644
--- a/java/com/google/gerrit/server/account/storage/notedb/AccountsUpdateNoteDbImpl.java
+++ b/java/com/google/gerrit/server/account/storage/notedb/AccountsUpdateNoteDbImpl.java
@@ -380,7 +380,8 @@
   }
 
   @Override
-  protected ImmutableList<Optional<AccountState>> executeUpdates(List<UpdateArguments> updates)
+  @VisibleForTesting
+  public ImmutableList<Optional<AccountState>> executeUpdates(List<UpdateArguments> updates)
       throws ConfigInvalidException, IOException {
     return execute(updates.stream().map(this::createExecutableUpdate).collect(toImmutableList()));
   }
diff --git a/java/com/google/gerrit/server/config/UserPreferencesConverter.java b/java/com/google/gerrit/server/config/UserPreferencesConverter.java
index 912abc4..4b2f6d2 100644
--- a/java/com/google/gerrit/server/config/UserPreferencesConverter.java
+++ b/java/com/google/gerrit/server/config/UserPreferencesConverter.java
@@ -17,7 +17,7 @@
 import static com.google.common.collect.ImmutableList.toImmutableList;
 
 import com.google.gerrit.common.Nullable;
-import com.google.gerrit.entities.converter.ProtoConverter;
+import com.google.gerrit.entities.converter.SafeProtoConverter;
 import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.extensions.client.EditPreferencesInfo;
 import com.google.gerrit.extensions.client.GeneralPreferencesInfo;
@@ -36,7 +36,8 @@
  */
 public final class UserPreferencesConverter {
   public enum GeneralPreferencesInfoConverter
-      implements ProtoConverter<UserPreferences.GeneralPreferencesInfo, GeneralPreferencesInfo> {
+      implements
+          SafeProtoConverter<UserPreferences.GeneralPreferencesInfo, GeneralPreferencesInfo> {
     GENERAL_PREFERENCES_INFO_CONVERTER;
 
     @Override
@@ -118,6 +119,14 @@
       builder =
           setIfNotNull(
               builder, builder::setAllowBrowserNotifications, info.allowBrowserNotifications);
+      builder =
+          setIfNotNull(
+              builder,
+              builder::setAllowSuggestCodeWhileCommenting,
+              info.allowSuggestCodeWhileCommenting);
+      builder =
+          setIfNotNull(
+              builder, builder::setAllowAutocompletingComments, info.allowAutocompletingComments);
       builder = setIfNotNull(builder, builder::setDiffPageSidebar, info.diffPageSidebar);
       return builder.build();
     }
@@ -180,6 +189,12 @@
       res.changeTable = proto.getChangeTableCount() != 0 ? proto.getChangeTableList() : null;
       res.allowBrowserNotifications =
           proto.hasAllowBrowserNotifications() ? proto.getAllowBrowserNotifications() : null;
+      res.allowSuggestCodeWhileCommenting =
+          proto.hasAllowSuggestCodeWhileCommenting()
+              ? proto.getAllowSuggestCodeWhileCommenting()
+              : null;
+      res.allowAutocompletingComments =
+          proto.hasAllowAutocompletingComments() ? proto.getAllowAutocompletingComments() : null;
       res.diffPageSidebar = proto.hasDiffPageSidebar() ? proto.getDiffPageSidebar() : null;
       return res;
     }
@@ -212,10 +227,20 @@
           proto.hasTarget() ? proto.getTarget().trim() : null,
           proto.hasId() ? proto.getId().trim() : null);
     }
+
+    @Override
+    public Class<UserPreferences.GeneralPreferencesInfo> getProtoClass() {
+      return UserPreferences.GeneralPreferencesInfo.class;
+    }
+
+    @Override
+    public Class<GeneralPreferencesInfo> getEntityClass() {
+      return GeneralPreferencesInfo.class;
+    }
   }
 
   public enum DiffPreferencesInfoConverter
-      implements ProtoConverter<UserPreferences.DiffPreferencesInfo, DiffPreferencesInfo> {
+      implements SafeProtoConverter<UserPreferences.DiffPreferencesInfo, DiffPreferencesInfo> {
     DIFF_PREFERENCES_INFO_CONVERTER;
 
     @Override
@@ -295,10 +320,20 @@
     public Parser<UserPreferences.DiffPreferencesInfo> getParser() {
       return UserPreferences.DiffPreferencesInfo.parser();
     }
+
+    @Override
+    public Class<UserPreferences.DiffPreferencesInfo> getProtoClass() {
+      return UserPreferences.DiffPreferencesInfo.class;
+    }
+
+    @Override
+    public Class<DiffPreferencesInfo> getEntityClass() {
+      return DiffPreferencesInfo.class;
+    }
   }
 
   public enum EditPreferencesInfoConverter
-      implements ProtoConverter<UserPreferences.EditPreferencesInfo, EditPreferencesInfo> {
+      implements SafeProtoConverter<UserPreferences.EditPreferencesInfo, EditPreferencesInfo> {
     EDIT_PREFERENCES_INFO_CONVERTER;
 
     @Override
@@ -347,6 +382,16 @@
     public Parser<UserPreferences.EditPreferencesInfo> getParser() {
       return UserPreferences.EditPreferencesInfo.parser();
     }
+
+    @Override
+    public Class<UserPreferences.EditPreferencesInfo> getProtoClass() {
+      return UserPreferences.EditPreferencesInfo.class;
+    }
+
+    @Override
+    public Class<EditPreferencesInfo> getEntityClass() {
+      return EditPreferencesInfo.class;
+    }
   }
 
   private static <ValueT, BuilderT extends Message.Builder> BuilderT setIfNotNull(
diff --git a/java/com/google/gerrit/server/git/ChangesByProjectCacheImpl.java b/java/com/google/gerrit/server/git/ChangesByProjectCacheImpl.java
index 2bbd261..17cc5a0 100644
--- a/java/com/google/gerrit/server/git/ChangesByProjectCacheImpl.java
+++ b/java/com/google/gerrit/server/git/ChangesByProjectCacheImpl.java
@@ -301,7 +301,9 @@
       size += JavaWeights.REFERENCE + (c.getTopic() == null ? 0 : c.getTopic().length());
       size +=
           JavaWeights.REFERENCE
-              + (c.getOriginalSubject().equals(c.getSubject()) ? 0 : c.getSubject().length());
+              + (c.getOriginalSubject().equals(c.getSubject())
+                  ? 0
+                  : c.getOriginalSubject().length());
       size +=
           JavaWeights.REFERENCE + (c.getSubmissionId() == null ? 0 : c.getSubmissionId().length());
       size += JavaWeights.REFERENCE + JavaWeights.BOOLEAN; // isPrivate;
@@ -309,7 +311,7 @@
       size += JavaWeights.REFERENCE + JavaWeights.BOOLEAN; // reviewStarted;
       size += JavaWeights.REFERENCE + (c.getRevertOf() == null ? 0 : GerritWeights.CHANGE_NUM);
       size +=
-          JavaWeights.REFERENCE + (c.getCherryPickOf() == null ? 0 : GerritWeights.PACTCH_SET_ID);
+          JavaWeights.REFERENCE + (c.getCherryPickOf() == null ? 0 : GerritWeights.PATCH_SET_ID);
       return size;
     }
 
@@ -343,7 +345,7 @@
     public static final int KEY_INT = JavaWeights.OBJECT + JavaWeights.INT; // IntKey
     public static final int CHANGE_NUM = KEY_INT;
     public static final int ACCOUNT_ID = KEY_INT;
-    public static final int PACTCH_SET_ID =
+    public static final int PATCH_SET_ID =
         JavaWeights.OBJECT
             + (JavaWeights.REFERENCE + GerritWeights.CHANGE_NUM) // PatchSet.Id.changeId
             + JavaWeights.INT; // PatchSet.Id patch_num;
diff --git a/java/com/google/gerrit/server/git/WorkQueue.java b/java/com/google/gerrit/server/git/WorkQueue.java
index 307ec5c..6f904ea 100644
--- a/java/com/google/gerrit/server/git/WorkQueue.java
+++ b/java/com/google/gerrit/server/git/WorkQueue.java
@@ -39,15 +39,20 @@
 import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Optional;
+import java.util.Set;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Delayed;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.FutureTask;
+import java.util.concurrent.PriorityBlockingQueue;
 import java.util.concurrent.RunnableScheduledFuture;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
@@ -56,7 +61,9 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.atomic.AtomicReference;
+import org.apache.commons.lang3.mutable.MutableBoolean;
 import org.eclipse.jgit.lib.Config;
 
 /** Delayed execution of tasks using a background thread pool. */
@@ -88,6 +95,54 @@
     void onStop(Task<?> task);
   }
 
+  /**
+   * Register a TaskParker from a plugin like this:
+   *
+   * <p>bind(TaskListener.class).annotatedWith(Exports.named("MyParker")).to(MyParker.class);
+   */
+  public interface TaskParker extends TaskListener {
+    class NoOp extends TaskListener.NoOp implements TaskParker {
+      @Override
+      public boolean isReadyToStart(Task<?> task) {
+        return true;
+      }
+
+      @Override
+      public void onNotReadyToStart(Task<?> task) {}
+    }
+
+    /**
+     * Determine whether a {@link Task} is ready to run or whether it should get parked.
+     *
+     * <p>Tasks that are not ready to run will get parked and will not run until all {@link
+     * TaskParker}s return {@code true} from this method for the {@link Task}. This method may be
+     * called more than once, but will always be followed by a call to {@link
+     * #onNotReadyToStart(Task)} before being called again.
+     *
+     * <p>Resources should be acquired in this method via non-blocking means to avoid delaying the
+     * executor from calling {@link #onNotReadyToStart(Task)} on other {@link TaskParker}s holding
+     * resources.
+     *
+     * @param task the {@link Task} being considered for starting/parking
+     * @return a boolean indicating if the given {@link Task} is ready to run ({@code true}) or
+     *     should be parked ({@code false})
+     */
+    boolean isReadyToStart(Task<?> task);
+
+    /**
+     * This method will be called after this {@link TaskParker} returns {@code true} from {@link
+     * #isReadyToStart(Task)} and another {@link TaskParker} returns {@code false}, thus preventing
+     * the start.
+     *
+     * <p>Implementors should use this method to free any resources acquired in {@link
+     * #isReadyToStart(Task)} based on the expectation that the task would start. Those resources
+     * can be re-acquired when {@link #isReadyToStart(Task)} is called again later.
+     *
+     * @param task the {@link Task} that was prevented from starting by another {@link TaskParker}
+     */
+    void onNotReadyToStart(Task<?> task);
+  }
+
   public static class Lifecycle implements LifecycleListener {
     private final WorkQueue workQueue;
 
@@ -288,9 +343,75 @@
 
   /** An isolated queue. */
   private class Executor extends ScheduledThreadPoolExecutor {
+    private class ParkedTask implements Comparable<ParkedTask> {
+      public final CancellableCountDownLatch latch = new CancellableCountDownLatch(1);
+      public final Task<?> task;
+      private final Long priority = priorityGenerator.getAndIncrement();
+
+      public ParkedTask(Task<?> task) {
+        this.task = task;
+      }
+
+      @Override
+      public int compareTo(ParkedTask o) {
+        return priority.compareTo(o.priority);
+      }
+
+      /**
+       * Cancel a parked {@link Task}.
+       *
+       * <p>Tasks awaiting in {@link #onStart(Task)} to be un-parked can be interrupted using this
+       * method.
+       */
+      public void cancel() {
+        latch.cancel();
+      }
+
+      public boolean isEqualTo(Task task) {
+        return this.task.taskId == task.taskId;
+      }
+    }
+
+    private class CancellableCountDownLatch extends CountDownLatch {
+      protected volatile boolean cancelled = false;
+
+      public CancellableCountDownLatch(int count) {
+        super(count);
+      }
+
+      /**
+       * Unblocks threads which are waiting until the latch has counted down to zero.
+       *
+       * <p>If the current count is zero, then this method returns immediately.
+       *
+       * <p>If the current count is greater than zero, then it decrements until the count reaches
+       * zero and causes all threads waiting on the latch using {@link CountDownLatch#await()} to
+       * throw an {@link InterruptedException}.
+       */
+      public void cancel() {
+        if (getCount() == 0) {
+          return;
+        }
+        this.cancelled = true;
+        while (getCount() > 0) {
+          countDown();
+        }
+      }
+
+      @Override
+      public void await() throws InterruptedException {
+        super.await();
+        if (cancelled) {
+          throw new InterruptedException();
+        }
+      }
+    }
+
     private final ConcurrentHashMap<Integer, Task<?>> all;
     private final ConcurrentHashMap<Runnable, Long> nanosPeriodByRunnable;
     private final String queueName;
+    private final AtomicLong priorityGenerator = new AtomicLong();
+    private final PriorityBlockingQueue<ParkedTask> parked = new PriorityBlockingQueue<>();
 
     Executor(int corePoolSize, final String queueName) {
       super(
@@ -488,7 +609,17 @@
     }
 
     void remove(Task<?> task) {
-      all.remove(task.getTaskId(), task);
+      boolean isRemoved = all.remove(task.getTaskId(), task);
+      if (isRemoved && !listeners.isEmpty()) {
+        cancelIfParked(task);
+      }
+    }
+
+    void cancelIfParked(Task<?> task) {
+      Optional<ParkedTask> parkedTask = parked.stream().filter(p -> p.isEqualTo(task)).findFirst();
+      if (parkedTask.isPresent()) {
+        parkedTask.get().cancel();
+      }
     }
 
     Task<?> getTask(int id) {
@@ -503,12 +634,86 @@
       return all.values();
     }
 
+    public void waitUntilReadyToStart(Task<?> task) {
+      if (!listeners.isEmpty() && !isReadyToStart(task)) {
+        incrementCorePoolSizeBy(1);
+        ParkedTask parkedTask = new ParkedTask(task);
+        parked.offer(parkedTask);
+        task.runningState.set(Task.State.PARKED);
+        try {
+          parkedTask.latch.await();
+        } catch (InterruptedException e) {
+          logger.atSevere().withCause(e).log("Parked Task(%s) Interrupted", task);
+          parked.remove(parkedTask);
+          incrementCorePoolSizeBy(-1);
+        }
+      }
+    }
+
     public void onStart(Task<?> task) {
       listeners.runEach(extension -> extension.get().onStart(task));
     }
 
     public void onStop(Task<?> task) {
       listeners.runEach(extension -> extension.get().onStop(task));
+      updateParked();
+    }
+
+    protected boolean isReadyToStart(Task<?> task) {
+      MutableBoolean isReady = new MutableBoolean(true);
+      Set<TaskParker> readyParkers = new HashSet<>();
+      listeners.runEach(
+          extension -> {
+            if (isReady.isTrue()) {
+              TaskListener listener = extension.get();
+              if (listener instanceof TaskParker) {
+                TaskParker parker = (TaskParker) listener;
+                if (parker.isReadyToStart(task)) {
+                  readyParkers.add(parker);
+                } else {
+                  isReady.setFalse();
+                }
+              }
+            }
+          });
+
+      if (isReady.isFalse()) {
+        listeners.runEach(
+            extension -> {
+              TaskListener listener = extension.get();
+              if (readyParkers.contains(listener)) {
+                ((TaskParker) listener).onNotReadyToStart(task);
+              }
+            });
+      }
+      return isReady.getValue();
+    }
+
+    public void updateParked() {
+      ParkedTask ready = parked.poll();
+      if (ready == null) {
+        return;
+      }
+      List<ParkedTask> notReady = new ArrayList<>();
+      while (ready != null && !isReadyToStart(ready.task)) {
+        notReady.add(ready);
+        ready = parked.poll();
+      }
+      parked.addAll(notReady);
+
+      if (ready != null) {
+        incrementCorePoolSizeBy(-1);
+        ready.latch.countDown();
+      }
+    }
+
+    public synchronized void incrementCorePoolSizeBy(int i) {
+      super.setCorePoolSize(getCorePoolSize() + i);
+    }
+
+    @Override
+    public synchronized void setCorePoolSize(int s) {
+      super.setCorePoolSize(s);
     }
   }
 
@@ -556,13 +761,14 @@
       // Ordered like this so ordinal matches the order we would
       // prefer to see tasks sorted in: done before running,
       // stopping before running, running before starting,
-      // starting before ready, ready before sleeping.
+      // starting before parked, parked before ready, ready before sleeping.
       //
       DONE,
       CANCELLED,
       STOPPING,
       RUNNING,
       STARTING,
+      PARKED,
       READY,
       SLEEPING,
       OTHER
@@ -694,12 +900,14 @@
 
     @Override
     public void run() {
-      if (runningState.compareAndSet(null, State.STARTING)) {
+      if (runningState.compareAndSet(null, State.READY)) {
         String oldThreadName = Thread.currentThread().getName();
         try {
+          Thread.currentThread().setName(oldThreadName + "[" + this + "]");
+          executor.waitUntilReadyToStart(this); // Transitions to PARKED while not ready to start
+          runningState.set(State.STARTING);
           executor.onStart(this);
           runningState.set(State.RUNNING);
-          Thread.currentThread().setName(oldThreadName + "[" + this + "]");
           task.run();
         } finally {
           Thread.currentThread().setName(oldThreadName);
diff --git a/java/com/google/gerrit/server/restapi/change/GetPatch.java b/java/com/google/gerrit/server/restapi/change/GetPatch.java
index d8946a7..749a241 100644
--- a/java/com/google/gerrit/server/restapi/change/GetPatch.java
+++ b/java/com/google/gerrit/server/restapi/change/GetPatch.java
@@ -17,6 +17,7 @@
 import static com.google.gerrit.git.ObjectIds.abbreviateName;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
+import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.extensions.restapi.BinaryResult;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
 import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
@@ -51,6 +52,10 @@
   @Option(name = "--path")
   private String path;
 
+  /** 1-based index of the parent's position in the commit object. */
+  @Option(name = "--parent", metaVar = "parent-number")
+  private Integer parentNum;
+
   @Inject
   GetPatch(GitRepositoryManager repoManager) {
     this.repoManager = repoManager;
@@ -58,7 +63,8 @@
 
   @Override
   public Response<BinaryResult> apply(RevisionResource rsrc)
-      throws ResourceConflictException, IOException, ResourceNotFoundException {
+      throws BadRequestException, ResourceConflictException, IOException,
+          ResourceNotFoundException {
     final Repository repo = repoManager.openRepository(rsrc.getProject());
     boolean close = true;
     try {
@@ -67,12 +73,16 @@
       try {
         final RevCommit commit = rw.parseCommit(rsrc.getPatchSet().commitId());
         RevCommit[] parents = commit.getParents();
-        if (parents.length > 1) {
+        if (parentNum == null && parents.length > 1) {
           throw new ResourceConflictException("Revision has more than 1 parent.");
-        } else if (parents.length == 0) {
+        }
+        if (parents.length == 0) {
           throw new ResourceConflictException("Revision has no parent.");
         }
-        final RevCommit base = parents[0];
+        if (parentNum != null && (parentNum < 1 || parentNum > parents.length)) {
+          throw new BadRequestException(String.format("invalid parent number: %d", parentNum));
+        }
+        final RevCommit base = parents[parentNum == null ? 0 : parentNum - 1];
         rw.parseBody(base);
 
         bin =
diff --git a/java/com/google/gerrit/server/restapi/config/GetSummary.java b/java/com/google/gerrit/server/restapi/config/GetSummary.java
index 77af0f3..c76f0a4 100644
--- a/java/com/google/gerrit/server/restapi/config/GetSummary.java
+++ b/java/com/google/gerrit/server/restapi/config/GetSummary.java
@@ -77,6 +77,7 @@
     int tasksTotal = pending.size();
     int tasksStopping = 0;
     int tasksRunning = 0;
+    int tasksParked = 0;
     int tasksStarting = 0;
     int tasksReady = 0;
     int tasksSleeping = 0;
@@ -88,6 +89,9 @@
         case RUNNING:
           tasksRunning++;
           break;
+        case PARKED:
+          tasksParked++;
+          break;
         case STARTING:
           tasksStarting++;
           break;
@@ -108,6 +112,7 @@
     taskSummary.total = toInteger(tasksTotal);
     taskSummary.stopping = toInteger(tasksStopping);
     taskSummary.running = toInteger(tasksRunning);
+    taskSummary.parked = toInteger(tasksParked);
     taskSummary.starting = toInteger(tasksStarting);
     taskSummary.ready = toInteger(tasksReady);
     taskSummary.sleeping = toInteger(tasksSleeping);
@@ -245,6 +250,7 @@
     public Integer total;
     public Integer stopping;
     public Integer running;
+    public Integer parked;
     public Integer starting;
     public Integer ready;
     public Integer sleeping;
diff --git a/java/com/google/gerrit/sshd/commands/ShowQueue.java b/java/com/google/gerrit/sshd/commands/ShowQueue.java
index 00361ad..14915bf 100644
--- a/java/com/google/gerrit/sshd/commands/ShowQueue.java
+++ b/java/com/google/gerrit/sshd/commands/ShowQueue.java
@@ -134,6 +134,7 @@
       switch (task.state) {
         case DONE:
         case CANCELLED:
+        case PARKED:
         case STARTING:
         case RUNNING:
         case STOPPING:
@@ -212,6 +213,8 @@
         return "";
       case STARTING:
         return "starting ...";
+      case PARKED:
+        return "parked .....";
       case READY:
         return "waiting ....";
       case SLEEPING:
diff --git a/javatests/com/google/gerrit/acceptance/api/accounts/GeneralPreferencesIT.java b/javatests/com/google/gerrit/acceptance/api/accounts/GeneralPreferencesIT.java
index 0b28f6f..afa9bca 100644
--- a/javatests/com/google/gerrit/acceptance/api/accounts/GeneralPreferencesIT.java
+++ b/javatests/com/google/gerrit/acceptance/api/accounts/GeneralPreferencesIT.java
@@ -85,6 +85,7 @@
     i.signedOffBy ^= true;
     i.allowBrowserNotifications ^= false;
     i.allowSuggestCodeWhileCommenting ^= false;
+    i.allowAutocompletingComments ^= false;
     i.diffPageSidebar = "plugin-insight";
     i.diffView = DiffView.UNIFIED_DIFF;
     i.my = new ArrayList<>();
@@ -99,6 +100,7 @@
     assertThat(o.theme).isEqualTo(i.theme);
     assertThat(o.allowBrowserNotifications).isEqualTo(i.allowBrowserNotifications);
     assertThat(o.allowSuggestCodeWhileCommenting).isEqualTo(i.allowSuggestCodeWhileCommenting);
+    assertThat(o.allowAutocompletingComments).isEqualTo(i.allowAutocompletingComments);
     assertThat(o.diffPageSidebar).isEqualTo(i.diffPageSidebar);
     assertThat(o.disableKeyboardShortcuts).isEqualTo(i.disableKeyboardShortcuts);
   }
diff --git a/javatests/com/google/gerrit/acceptance/rest/change/CreateChangeIT.java b/javatests/com/google/gerrit/acceptance/rest/change/CreateChangeIT.java
index df7cd8f..1e03f2d 100644
--- a/javatests/com/google/gerrit/acceptance/rest/change/CreateChangeIT.java
+++ b/javatests/com/google/gerrit/acceptance/rest/change/CreateChangeIT.java
@@ -1186,6 +1186,52 @@
   }
 
   @Test
+  public void changePatch_multipleParents_success() throws Exception {
+    changeInTwoBranches("branchA", "a.txt", "branchB", "b.txt");
+    ChangeInput in = newMergeChangeInput("branchA", "branchB", "");
+    ChangeInfo change = assertCreateSucceeds(in);
+
+    RestResponse patchResp =
+        userRestSession.get("/changes/" + change.id + "/revisions/current/patch?parent=1");
+    patchResp.assertOK();
+    assertThat(new String(Base64.decode(patchResp.getEntityContent()), UTF_8))
+        .contains("+B content");
+
+    patchResp = userRestSession.get("/changes/" + change.id + "/revisions/current/patch?parent=2");
+    patchResp.assertOK();
+    assertThat(new String(Base64.decode(patchResp.getEntityContent()), UTF_8))
+        .contains("+A content");
+  }
+
+  @Test
+  public void changePatch_multipleParents_failure() throws Exception {
+    changeInTwoBranches("branchA", "a.txt", "branchB", "b.txt");
+    ChangeInput in = newMergeChangeInput("branchA", "branchB", "");
+    ChangeInfo change = assertCreateSucceeds(in);
+
+    RestResponse patchResp =
+        userRestSession.get("/changes/" + change.id + "/revisions/current/patch");
+    // Maintaining historic logic of failing with 409 Conflict in this case.
+    patchResp.assertConflict();
+  }
+
+  @Test
+  public void changePatch_parent_badRequest() throws Exception {
+    changeInTwoBranches("branchA", "a.txt", "branchB", "b.txt");
+    ChangeInput in = newMergeChangeInput("branchA", "branchB", "");
+    ChangeInfo change = assertCreateSucceeds(in);
+
+    RestResponse patchResp =
+        userRestSession.get("/changes/" + change.id + "/revisions/current/patch?parent=3");
+    // Parent 3 does not exist.
+    patchResp.assertBadRequest();
+
+    patchResp = userRestSession.get("/changes/" + change.id + "/revisions/current/patch?parent=0");
+    // Parent 0 does not exist.
+    patchResp.assertBadRequest();
+  }
+
+  @Test
   @UseSystemTime
   public void sha1sOfTwoNewChangesDiffer() throws Exception {
     ChangeInput changeInput = newChangeInput(ChangeStatus.NEW);
diff --git a/javatests/com/google/gerrit/acceptance/server/util/TaskListenerIT.java b/javatests/com/google/gerrit/acceptance/server/util/TaskListenerIT.java
index 809cee9..9e9e1c2 100644
--- a/javatests/com/google/gerrit/acceptance/server/util/TaskListenerIT.java
+++ b/javatests/com/google/gerrit/acceptance/server/util/TaskListenerIT.java
@@ -34,109 +34,147 @@
 public class TaskListenerIT extends AbstractDaemonTest {
   /**
    * Use a LatchedMethod in a method to allow another thread to await the method's call. Once
-   * called, the Latch.call() method will block until another thread calls its LatchedMethods's
-   * complete() method.
+   * called, the call() method will block until another thread calls the complete() method or until
+   * a preset timeout is reached.
    */
-  private static class LatchedMethod {
-    private static final int AWAIT_TIMEOUT = 20;
-    private static final TimeUnit AWAIT_TIMEUNIT = TimeUnit.MILLISECONDS;
-
-    /** API class meant be used by the class whose method is being latched */
-    private class Latch {
-      /** Ensure that the latched method calls this on entry */
-      public void call() {
-        called.countDown();
-        await(complete);
-      }
-    }
-
-    public Latch latch = new Latch();
+  public static class LatchedMethod<T> {
+    private volatile T value;
 
     private final CountDownLatch called = new CountDownLatch(1);
     private final CountDownLatch complete = new CountDownLatch(1);
 
-    /** Assert that the Latch's call() method has not yet been called */
+    /** Assert that the call() method has not yet been called */
     public void assertUncalled() {
       assertThat(called.getCount()).isEqualTo(1);
     }
 
     /**
-     * Assert that a timeout does not occur while awaiting Latch's call() method to be called. Fails
-     * if the waiting time elapses before Latch's call() method is called, otherwise passes.
+     * Assert that a timeout does not occur while awaiting the call() to be called. Fails if the
+     * waiting time elapses before the call() method is called, otherwise passes.
      */
-    public void assertAwait() {
+    public void assertCalledEventually() {
       assertThat(await(called)).isEqualTo(true);
     }
 
-    /** Unblock the Latch's call() method so that it can complete */
+    public T call() {
+      called.countDown();
+      await(complete);
+      return getValue();
+    }
+
+    public T call(T val) {
+      set(val);
+      return call();
+    }
+
+    public T callAndAwaitComplete() throws InterruptedException {
+      called.countDown();
+      complete.await();
+      return getValue();
+    }
+
     public void complete() {
       complete.countDown();
     }
 
-    @CanIgnoreReturnValue
-    private static boolean await(CountDownLatch latch) {
-      try {
-        return latch.await(AWAIT_TIMEOUT, AWAIT_TIMEUNIT);
-      } catch (InterruptedException e) {
-        return false;
-      }
+    public void set(T val) {
+      value = val;
+    }
+
+    public void complete(T val) {
+      set(val);
+      complete();
+    }
+
+    public void assertCalledEventuallyThenComplete(T val) {
+      assertCalledEventually();
+      complete(val);
+    }
+
+    protected T getValue() {
+      return value;
     }
   }
 
-  private static class LatchedRunnable implements Runnable {
-    public LatchedMethod run = new LatchedMethod();
+  public static class LatchedRunnable implements Runnable {
+    public LatchedMethod<?> run = new LatchedMethod<>();
+    public String name = "latched-runnable";
+
+    public LatchedRunnable(String name) {
+      this.name = name;
+    }
+
+    public LatchedRunnable() {}
 
     @Override
     public void run() {
-      run.latch.call();
+      run.call();
+    }
+
+    @Override
+    public String toString() {
+      return name;
     }
   }
 
-  private static class ForwardingListener implements TaskListener {
-    public volatile TaskListener delegate;
+  public static class ForwardingListener<T extends TaskListener> implements TaskListener {
+    public volatile T delegate;
     public volatile Task<?> task;
 
-    public void resetDelegate(TaskListener listener) {
+    public void resetDelegate(T listener) {
       delegate = listener;
       task = null;
     }
 
     @Override
     public void onStart(Task<?> task) {
-      if (delegate != null) {
-        if (this.task == null || this.task == task) {
-          this.task = task;
-          delegate.onStart(task);
-        }
+      if (isDelegatable(task)) {
+        delegate.onStart(task);
       }
     }
 
     @Override
     public void onStop(Task<?> task) {
+      if (isDelegatable(task)) {
+        delegate.onStop(task);
+      }
+    }
+
+    protected boolean isDelegatable(Task<?> task) {
       if (delegate != null) {
         if (this.task == task) {
-          delegate.onStop(task);
+          return true;
+        }
+        if (this.task == null) {
+          this.task = task;
+          return true;
         }
       }
+      return false;
     }
   }
 
-  private static class LatchedListener implements TaskListener {
-    public LatchedMethod onStart = new LatchedMethod();
-    public LatchedMethod onStop = new LatchedMethod();
+  public static class LatchedListener implements TaskListener {
+    public LatchedMethod<?> onStart = new LatchedMethod<>();
+    public LatchedMethod<?> onStop = new LatchedMethod<>();
 
     @Override
     public void onStart(Task<?> task) {
-      onStart.latch.call();
+      onStart.call();
     }
 
     @Override
     public void onStop(Task<?> task) {
-      onStop.latch.call();
+      onStop.call();
     }
   }
 
-  private static ForwardingListener forwarder;
+  private static final int AWAIT_TIMEOUT = 20;
+  private static final TimeUnit AWAIT_TIMEUNIT = TimeUnit.MILLISECONDS;
+  private static final long MS_EMPTY_QUEUE =
+      TimeUnit.MILLISECONDS.convert(50, TimeUnit.MILLISECONDS);
+
+  private static ForwardingListener<TaskListener> forwarder;
 
   @Inject private WorkQueue workQueue;
   private ScheduledExecutorService executor;
@@ -149,9 +187,9 @@
     return new AbstractModule() {
       @Override
       public void configure() {
-        // Forwarder.delegate is empty on start to protect test listener from non test tasks
-        // (such as the "Log File Manager") interference
-        forwarder = new ForwardingListener(); // Only gets bound once for all tests
+        // Forwarder.delegate is empty on start to protect test listener from non-test tasks (such
+        // as the "Log File Manager") interference
+        forwarder = new ForwardingListener<>(); // Only gets bound once for all tests
         bind(TaskListener.class).annotatedWith(Exports.named("listener")).toInstance(forwarder);
       }
     };
@@ -184,23 +222,23 @@
     int size = assertQueueBlockedOnExecution(runnable);
 
     // onStartThenRunThenOnStopAreCalled -> onStart...Called
-    listener.onStart.assertAwait();
+    listener.onStart.assertCalledEventually();
     assertQueueSize(size);
     runnable.run.assertUncalled();
     listener.onStop.assertUncalled();
 
     listener.onStart.complete();
     // onStartThenRunThenOnStopAreCalled -> ...ThenRun...Called
-    runnable.run.assertAwait();
+    runnable.run.assertCalledEventually();
     listener.onStop.assertUncalled();
 
     runnable.run.complete();
     // onStartThenRunThenOnStopAreCalled -> ...ThenOnStop...Called
-    listener.onStop.assertAwait();
+    listener.onStop.assertCalledEventually();
     assertQueueSize(size);
 
     listener.onStop.complete();
-    assertAwaitQueueSize(--size);
+    assertTaskCountIsEventually(--size);
   }
 
   @Test
@@ -208,7 +246,7 @@
     int size = assertQueueBlockedOnExecution(runnable);
 
     // firstBlocksSecond -> first...
-    listener.onStart.assertAwait();
+    listener.onStart.assertCalledEventually();
     assertQueueSize(size);
 
     LatchedRunnable runnable2 = new LatchedRunnable();
@@ -219,35 +257,35 @@
     assertQueueSize(size); // waiting on first
 
     listener.onStart.complete();
-    runnable.run.assertAwait();
+    runnable.run.assertCalledEventually();
     assertQueueSize(size); // waiting on first
     runnable2.run.assertUncalled();
 
     runnable.run.complete();
-    listener.onStop.assertAwait();
+    listener.onStop.assertCalledEventually();
     assertQueueSize(size); // waiting on first
     runnable2.run.assertUncalled();
 
     listener.onStop.complete();
-    runnable2.run.assertAwait();
+    runnable2.run.assertCalledEventually();
     assertQueueSize(--size);
 
     runnable2.run.complete();
-    assertAwaitQueueSize(--size);
+    assertTaskCountIsEventually(--size);
   }
 
   @Test
   public void states() throws Exception {
     executor.execute(runnable);
-    listener.onStart.assertAwait();
+    listener.onStart.assertCalledEventually();
     assertStateIs(Task.State.STARTING);
 
     listener.onStart.complete();
-    runnable.run.assertAwait();
+    runnable.run.assertCalledEventually();
     assertStateIs(Task.State.RUNNING);
 
     runnable.run.complete();
-    listener.onStop.assertAwait();
+    listener.onStop.assertCalledEventually();
     assertStateIs(Task.State.STOPPING);
 
     listener.onStop.complete();
@@ -255,8 +293,40 @@
     assertStateIs(Task.State.DONE);
   }
 
+  /** Fails if the waiting time elapses before the count is reached, otherwise passes */
+  public static void assertTaskCountIsEventually(WorkQueue workQueue, int count)
+      throws InterruptedException {
+    long ms = 0;
+    while (count != workQueue.getTasks().size()) {
+      assertThat(ms++).isLessThan(MS_EMPTY_QUEUE);
+      TimeUnit.MILLISECONDS.sleep(1);
+    }
+  }
+
+  public static void assertQueueSize(WorkQueue workQueue, int size) {
+    assertThat(workQueue.getTasks().size()).isEqualTo(size);
+  }
+
+  @CanIgnoreReturnValue
+  public static boolean await(CountDownLatch latch) {
+    try {
+      return latch.await(AWAIT_TIMEOUT, AWAIT_TIMEUNIT);
+    } catch (InterruptedException e) {
+      return false;
+    }
+  }
+
+  public void assertTaskCountIsEventually(int count) throws InterruptedException {
+    TaskListenerIT.assertTaskCountIsEventually(workQueue, count);
+  }
+
+  public static void assertStateIs(Task<?> task, Task.State state) {
+    assertThat(task).isNotNull();
+    assertThat(task.getState()).isEqualTo(state);
+  }
+
   private void assertStateIs(Task.State state) {
-    assertThat(forwarder.task.getState()).isEqualTo(state);
+    assertStateIs(forwarder.task, state);
   }
 
   private int assertQueueBlockedOnExecution(Runnable runnable) {
@@ -267,19 +337,10 @@
   }
 
   private void assertQueueSize(int size) {
-    assertThat(workQueue.getTasks().size()).isEqualTo(size);
+    assertQueueSize(workQueue, size);
   }
 
   private void assertAwaitQueueIsEmpty() throws InterruptedException {
-    assertAwaitQueueSize(0);
-  }
-
-  /** Fails if the waiting time elapses before the count is reached, otherwise passes */
-  private void assertAwaitQueueSize(int size) throws InterruptedException {
-    long i = 0;
-    do {
-      TimeUnit.NANOSECONDS.sleep(100);
-      assertThat(i++).isLessThan(1000);
-    } while (size != workQueue.getTasks().size());
+    assertTaskCountIsEventually(0);
   }
 }
diff --git a/javatests/com/google/gerrit/acceptance/server/util/TaskParkerIT.java b/javatests/com/google/gerrit/acceptance/server/util/TaskParkerIT.java
new file mode 100644
index 0000000..3b82ebe
--- /dev/null
+++ b/javatests/com/google/gerrit/acceptance/server/util/TaskParkerIT.java
@@ -0,0 +1,548 @@
+// Copyright (C) 2022 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.acceptance.server.util;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.gerrit.acceptance.AbstractDaemonTest;
+import com.google.gerrit.acceptance.server.util.TaskListenerIT.LatchedMethod;
+import com.google.gerrit.acceptance.server.util.TaskListenerIT.LatchedRunnable;
+import com.google.gerrit.extensions.annotations.Exports;
+import com.google.gerrit.server.git.WorkQueue;
+import com.google.gerrit.server.git.WorkQueue.Task;
+import com.google.gerrit.server.git.WorkQueue.Task.State;
+import com.google.gerrit.server.git.WorkQueue.TaskListener;
+import com.google.gerrit.server.git.WorkQueue.TaskParker;
+import com.google.inject.AbstractModule;
+import com.google.inject.Inject;
+import com.google.inject.Module;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+public class TaskParkerIT extends AbstractDaemonTest {
+  private static class ForwardingParker extends TaskListenerIT.ForwardingListener<LatchedParker>
+      implements TaskParker {
+    public AtomicInteger isReadyToStartCounter = new AtomicInteger(0);
+    public AtomicInteger onNotReadyToStartCounter = new AtomicInteger(0);
+
+    @Override
+    public boolean isReadyToStart(Task<?> task) {
+      isReadyToStartCounter.incrementAndGet();
+      if (isDelegatable(task)) {
+        return delegate.isReadyToStart(task);
+      }
+      return true;
+    }
+
+    @Override
+    public void onNotReadyToStart(Task<?> task) {
+      onNotReadyToStartCounter.incrementAndGet();
+      if (isDelegatable(task)) {
+        delegate.onNotReadyToStart(task);
+      }
+    }
+
+    public void resetCounters() {
+      isReadyToStartCounter.getAndSet(0);
+      onNotReadyToStartCounter.getAndSet(0);
+    }
+  }
+
+  public static class LatchedParker extends TaskListenerIT.LatchedListener implements TaskParker {
+    private static final String EXPENSIVE_TASK = "expensive-task";
+    private final Semaphore expensiveTaskSemaphore = new Semaphore(1, true);
+    public volatile LatchedMethod<Boolean> isReadyToStart = new LatchedMethod<>();
+    public volatile LatchedMethod<?> onNotReadyToStart = new LatchedMethod<>();
+
+    @Override
+    public boolean isReadyToStart(Task<?> task) {
+      Boolean rtn = isReadyToStart.call();
+      if (EXPENSIVE_TASK.equals(task.toString()) && !expensiveTaskSemaphore.tryAcquire()) {
+        return false;
+      }
+      isReadyToStart = new LatchedMethod<>();
+      if (rtn != null) {
+        return rtn;
+      }
+      return true;
+    }
+
+    @Override
+    public void onNotReadyToStart(Task<?> task) {
+      onNotReadyToStart.call();
+      onNotReadyToStart = new LatchedMethod<>();
+    }
+
+    @Override
+    public void onStop(Task<?> task) {
+      if (EXPENSIVE_TASK.equals(task.toString())) {
+        expensiveTaskSemaphore.release();
+      }
+      super.onStop(task);
+    }
+  }
+
+  public static class LatchedForeverRunnable extends LatchedRunnable {
+    public LatchedForeverRunnable(String name) {
+      super(name);
+    }
+
+    @Override
+    public void run() {
+      try {
+        run.callAndAwaitComplete();
+      } catch (InterruptedException e) {
+        throw new RuntimeException(e);
+      }
+    }
+  }
+
+  private static ForwardingParker forwarder;
+  private static ForwardingParker forwarder2;
+  public static final long TIMEOUT = TimeUnit.MILLISECONDS.convert(200, TimeUnit.MILLISECONDS);
+
+  private final LatchedParker parker = new LatchedParker();
+
+  @Inject private WorkQueue workQueue;
+  private ScheduledExecutorService executor;
+
+  @Before
+  public void setupExecutorAndForwarder() throws InterruptedException {
+    executor = workQueue.createQueue(1, "TaskParkers");
+    // "Log File Manager"s are likely running and will interfere with tests
+    while (0 != workQueue.getTasks().size()) {
+      for (Task<?> t : workQueue.getTasks()) {
+        t.cancel(true);
+      }
+      TimeUnit.MILLISECONDS.sleep(1);
+    }
+    forwarder.delegate = parker;
+    forwarder.task = null;
+    forwarder.resetCounters();
+    forwarder2.delegate = null; // load only if test needs it
+    forwarder2.task = null;
+    forwarder2.resetCounters();
+  }
+
+  @After
+  public void shutdownExecutor() throws InterruptedException {
+    executor.shutdownNow();
+    executor.awaitTermination(1, TimeUnit.SECONDS);
+  }
+
+  @Override
+  public Module createModule() {
+    return new AbstractModule() {
+      @Override
+      public void configure() {
+        // Forwarder.delegate is empty on start to protect test parker from non-test tasks (such as
+        // the "Log File Manager") interference
+        forwarder = new ForwardingParker(); // Only gets bound once for all tests
+        bind(TaskListener.class).annotatedWith(Exports.named("parker")).toInstance(forwarder);
+        forwarder2 = new ForwardingParker();
+        bind(TaskListener.class).annotatedWith(Exports.named("parker2")).toInstance(forwarder2);
+      }
+    };
+  }
+
+  @Test
+  public void noParkFlow() throws Exception {
+    LatchedRunnable runnable = new LatchedRunnable();
+
+    assertTaskCountIs(0);
+    assertThat(forwarder.task).isEqualTo(null);
+    parker.isReadyToStart.assertUncalled();
+    parker.onNotReadyToStart.assertUncalled();
+    parker.onStart.assertUncalled();
+    runnable.run.assertUncalled();
+    parker.onStop.assertUncalled();
+    assertCorePoolSizeIs(1);
+
+    executor.execute(runnable);
+    assertTaskCountIs(1);
+
+    parker.isReadyToStart.assertCalledEventually();
+    assertTaskCountIs(1);
+    assertStateIs(State.READY);
+    parker.onNotReadyToStart.assertUncalled();
+    parker.onStart.assertUncalled();
+    runnable.run.assertUncalled();
+    parker.onStop.assertUncalled();
+
+    parker.isReadyToStart.complete();
+    parker.onStart.assertCalledEventually();
+    assertStateIs(State.STARTING);
+    assertTaskCountIs(1);
+    parker.onNotReadyToStart.assertUncalled();
+    runnable.run.assertUncalled();
+    parker.onStop.assertUncalled();
+
+    parker.onStart.complete();
+    runnable.run.assertCalledEventually();
+    assertStateIs(State.RUNNING);
+    assertTaskCountIs(1);
+    parker.onNotReadyToStart.assertUncalled();
+    parker.onStop.assertUncalled();
+
+    runnable.run.complete();
+    parker.onStop.assertCalledEventually();
+    assertStateIs(State.STOPPING);
+    assertTaskCountIs(1);
+    parker.onNotReadyToStart.assertUncalled();
+
+    parker.onStop.complete();
+    assertTaskCountIsEventually(0);
+    assertStateIs(State.DONE);
+    parker.onNotReadyToStart.assertUncalled();
+    assertCorePoolSizeIs(1);
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 1);
+    assertCounter(forwarder.onNotReadyToStartCounter, 0);
+  }
+
+  @Test
+  public void parkFirstSoSecondRuns() throws Exception {
+    LatchedRunnable runnable1 = new LatchedRunnable();
+    LatchedRunnable runnable2 = new LatchedRunnable();
+    assertCorePoolSizeIs(1);
+
+    executor.execute(runnable1);
+    parker.isReadyToStart.assertCalledEventually();
+    Task<?> task1 = forwarder.task; // task for runnable1
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 1);
+    assertCounter(forwarder.onNotReadyToStartCounter, 0);
+    executor.execute(runnable2);
+    assertTaskCountIs(2);
+    parker.onNotReadyToStart.assertUncalled();
+    parker.onStart.assertUncalled();
+    runnable1.run.assertUncalled();
+    parker.onStop.assertUncalled();
+
+    // park runnable1
+    parker.isReadyToStart.complete(false);
+    assertCorePoolSizeIsEventually(2);
+    assertStateIs(task1, State.PARKED);
+
+    runnable2.run.assertCalledEventually();
+    assertTaskCountIs(2);
+    parker.onNotReadyToStart.assertUncalled();
+    parker.onStart.assertUncalled();
+    runnable1.run.assertUncalled();
+    parker.onStop.assertUncalled();
+    assertStateIs(task1, State.PARKED);
+
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 2);
+    assertCounter(forwarder.onNotReadyToStartCounter, 0);
+    runnable2.run.complete();
+
+    parker.isReadyToStart.assertCalledEventually();
+    parker.onNotReadyToStart.assertUncalled();
+    parker.onStart.assertUncalled();
+    runnable1.run.assertUncalled();
+    parker.onStop.assertUncalled();
+
+    parker.isReadyToStart.complete(true);
+    parker.onStart.assertCalledEventually();
+    assertStateIs(task1, State.STARTING);
+    assertTaskCountIsEventually(1);
+    parker.onNotReadyToStart.assertUncalled();
+    runnable1.run.assertUncalled();
+    parker.onStop.assertUncalled();
+
+    parker.onStart.complete();
+    runnable1.run.assertCalledEventually();
+    assertStateIs(task1, State.RUNNING);
+    assertTaskCountIs(1);
+    parker.onNotReadyToStart.assertUncalled();
+    parker.onStop.assertUncalled();
+
+    runnable1.run.complete();
+    parker.onStop.assertCalledEventually();
+    assertStateIs(task1, State.STOPPING);
+    assertTaskCountIs(1);
+    parker.onNotReadyToStart.assertUncalled();
+
+    parker.onStop.complete();
+    assertCorePoolSizeIsEventually(1);
+    assertTaskCountIsEventually(0);
+    assertStateIs(task1, State.DONE);
+    parker.onNotReadyToStart.assertUncalled();
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 3);
+    assertCounter(forwarder.onNotReadyToStartCounter, 0);
+  }
+
+  @Test
+  public void unParkPriorityOrder() throws Exception {
+    LatchedRunnable runnable1 = new LatchedRunnable();
+    LatchedRunnable runnable2 = new LatchedRunnable();
+    LatchedRunnable runnable3 = new LatchedRunnable();
+
+    // park runnable1
+    assertCorePoolSizeIs(1);
+    executor.execute(runnable1);
+    parker.isReadyToStart.assertCalledEventuallyThenComplete(false);
+    Task<?> task1 = forwarder.task; // task for runnable1
+    assertStateIsEventually(task1, State.PARKED);
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 1);
+    assertCounter(forwarder.onNotReadyToStartCounter, 0);
+    assertTaskCountIsEventually(1);
+    assertCorePoolSizeIsEventually(2);
+
+    // park runnable2
+    forwarder.resetDelegate(parker);
+    executor.execute(runnable2);
+    parker.isReadyToStart.assertCalledEventuallyThenComplete(false);
+    Task<?> task2 = forwarder.task; // task for runnable2
+    assertStateIsEventually(task2, State.PARKED);
+
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 2);
+    assertCounter(forwarder.onNotReadyToStartCounter, 0);
+    assertTaskCountIsEventually(2);
+    assertCorePoolSizeIsEventually(3);
+
+    // set parker to ready and execute runnable3
+    forwarder.resetDelegate(parker);
+    executor.execute(runnable3);
+
+    // assert runnable3 finishes executing and runnable1, runnable2 stay parked
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 3);
+    assertCounter(forwarder.onNotReadyToStartCounter, 0);
+    parker.isReadyToStart.assertCalledEventually();
+    Task<?> task3 = forwarder.task; // task for runnable3
+    assertStateIs(task3, State.READY);
+    parker.isReadyToStart.complete(true);
+    parker.onStart.assertCalledEventually();
+    assertStateIs(task3, State.STARTING);
+    parker.onStart.complete();
+    runnable3.run.assertCalledEventually();
+    assertStateIs(task3, State.RUNNING);
+    runnable1.run.assertUncalled();
+    runnable2.run.assertUncalled();
+    runnable3.run.complete();
+    parker.onStop.assertCalledEventually();
+    assertStateIs(task3, State.STOPPING);
+    parker.onStop.complete();
+    assertTaskCountIsEventually(2);
+    assertStateIs(task3, State.DONE);
+
+    // assert runnable1 finishes executing and runnable2 stays parked
+    runnable1.run.assertCalledEventually();
+    assertStateIs(task1, State.RUNNING);
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 4);
+    assertCounter(forwarder.onNotReadyToStartCounter, 0);
+    runnable2.run.assertUncalled();
+    assertStateIs(task2, State.PARKED);
+    runnable1.run.complete();
+    assertCorePoolSizeIsEventually(2);
+    assertTaskCountIsEventually(1);
+    assertStateIs(task1, State.DONE);
+
+    // assert runnable2 finishes executing
+    runnable2.run.assertCalledEventually();
+    assertStateIs(task2, State.RUNNING);
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 5);
+    assertCounter(forwarder.onNotReadyToStartCounter, 0);
+    runnable2.run.complete();
+    assertCorePoolSizeIsEventually(1);
+    assertTaskCountIsEventually(0);
+    assertStateIs(task2, State.DONE);
+  }
+
+  @Test
+  public void notReadyToStartIsCalledOnReadyListenerWhenAnotherListenerIsNotReady()
+      throws InterruptedException {
+    LatchedRunnable runnable1 = new LatchedRunnable();
+    LatchedRunnable runnable2 = new LatchedRunnable();
+
+    LatchedParker parker2 = new LatchedParker();
+    forwarder2.delegate = parker2;
+
+    // park runnable1 (parker1 is ready and parker2 is not ready)
+    assertCorePoolSizeIs(1);
+    executor.execute(runnable1);
+    parker2.isReadyToStart.complete(false);
+
+    assertTaskCountIsEventually(1);
+    assertCorePoolSizeIsEventually(2);
+
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 1);
+    assertCounterIsEventually(forwarder.onNotReadyToStartCounter, 1);
+    assertCounterIsEventually(forwarder2.isReadyToStartCounter, 1);
+    assertCounter(forwarder2.onNotReadyToStartCounter, 0);
+    Task<?> task1 = forwarder.task; // task for runnable1
+    assertStateIsEventually(task1, State.PARKED);
+
+    // set parker2 to ready and execute runnable-2
+    parker2.isReadyToStart.set(true);
+    forwarder.resetDelegate(parker);
+    forwarder2.resetDelegate(parker2);
+    executor.execute(runnable2);
+
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 2);
+    assertCounterIsEventually(forwarder.onNotReadyToStartCounter, 1);
+    assertCounterIsEventually(forwarder2.isReadyToStartCounter, 2);
+    assertCounter(forwarder2.onNotReadyToStartCounter, 0);
+    Task<?> task2 = forwarder.task; // task for runnable2
+
+    assertCorePoolSizeIsEventually(1);
+    runnable2.run.assertCalledEventually();
+    runnable2.run.complete();
+    assertTaskCountIsEventually(1);
+    assertStateIs(task2, State.DONE);
+
+    assertCounterIsEventually(forwarder.isReadyToStartCounter, 3);
+    assertCounterIsEventually(forwarder.onNotReadyToStartCounter, 1);
+    assertCounterIsEventually(forwarder2.isReadyToStartCounter, 3);
+    assertCounter(forwarder2.onNotReadyToStartCounter, 0);
+
+    runnable1.run.assertCalledEventually();
+    runnable1.run.complete();
+    assertTaskCountIsEventually(0);
+    assertStateIs(task1, State.DONE);
+  }
+
+  @Test
+  public void runFirstParkSecondUsingTaskName() throws InterruptedException {
+    LatchedForeverRunnable runnable1 = new LatchedForeverRunnable("expensive-task");
+    LatchedRunnable runnable2 = new LatchedRunnable("expensive-task");
+    LatchedParker parker = new LatchedParker();
+    executor = workQueue.createQueue(2, "TaskParkers");
+    assertCorePoolSizeIs(2);
+
+    forwarder.resetDelegate(parker);
+    executor.execute(runnable1);
+    parker.isReadyToStart.complete();
+    parker.onStart.complete();
+    runnable1.run.assertCalledEventually();
+    assertTaskCountIsEventually(1);
+    assertCorePoolSizeIs(2);
+    Task<?> task1 = forwarder.task; // task for runnable1
+    assertStateIs(task1, State.RUNNING);
+
+    forwarder.resetDelegate(parker);
+    executor.execute(runnable2);
+    parker.isReadyToStart.assertCalledEventually();
+    assertCorePoolSizeIsEventually(3);
+    Task<?> task2 = forwarder.task; // task for runnable2
+    assertStateIs(task2, State.PARKED);
+
+    forwarder.resetDelegate(parker);
+    runnable1.run.complete(); // unblock runnable1
+
+    assertCorePoolSizeIsEventually(2);
+    assertTaskCountIsEventually(0); // assert both tasks finish
+  }
+
+  @Test
+  public void interruptingParkedTaskDecrementsCorePoolSize() throws InterruptedException {
+    String taskName = "to-be-parked";
+    LatchedRunnable runnable1 = new LatchedRunnable(taskName);
+    assertCorePoolSizeIs(1);
+
+    // park runnable1
+    executor.execute(runnable1);
+    parker.isReadyToStart.assertCalledEventuallyThenComplete(false);
+    assertCorePoolSizeIsEventually(2);
+    assertStateIsEventually(forwarder.task, State.PARKED);
+
+    // interrupt the thread with parked task
+    for (Thread t : Thread.getAllStackTraces().keySet()) {
+      if (t.getName().contains(taskName)) {
+        t.interrupt();
+        break;
+      }
+    }
+
+    assertCorePoolSizeIsEventually(1);
+  }
+
+  @Test
+  public void canCancelParkedTask() throws InterruptedException {
+    LatchedRunnable runnable1 = new LatchedRunnable();
+    assertCorePoolSizeIs(1);
+
+    // park runnable1
+    executor.execute(runnable1);
+    parker.isReadyToStart.assertCalledEventuallyThenComplete(false);
+    assertCorePoolSizeIsEventually(2);
+    Task<?> task = forwarder.task;
+    assertStateIsEventually(task, State.PARKED);
+
+    // cancel parked task
+    task.cancel(true);
+
+    // assert core pool size is reduced and task is cancelled
+    assertCorePoolSizeIsEventually(1);
+    assertTaskCountIsEventually(0);
+    assertStateIs(State.CANCELLED);
+  }
+
+  private void assertTaskCountIs(int size) {
+    TaskListenerIT.assertQueueSize(workQueue, size);
+  }
+
+  private void assertTaskCountIsEventually(int count) throws InterruptedException {
+    TaskListenerIT.assertTaskCountIsEventually(workQueue, count);
+  }
+
+  private void assertCorePoolSizeIs(int count) {
+    assertThat(count).isEqualTo(((ScheduledThreadPoolExecutor) executor).getCorePoolSize());
+  }
+
+  private void assertCorePoolSizeIsEventually(int count) throws InterruptedException {
+    ScheduledThreadPoolExecutor scheduledThreadPoolExecutor =
+        (ScheduledThreadPoolExecutor) executor;
+    long ms = 0;
+    while (count != scheduledThreadPoolExecutor.getCorePoolSize()) {
+      assertThat(ms++).isLessThan(TIMEOUT);
+      TimeUnit.MILLISECONDS.sleep(1);
+    }
+  }
+
+  private void assertCounter(AtomicInteger counter, int desiredCount) {
+    assertThat(counter.get()).isEqualTo(desiredCount);
+  }
+
+  private void assertCounterIsEventually(AtomicInteger counter, int desiredCount)
+      throws InterruptedException {
+    long ms = 0;
+    while (desiredCount != counter.get()) {
+      assertThat(ms++).isLessThan(TIMEOUT);
+      TimeUnit.MILLISECONDS.sleep(1);
+    }
+  }
+
+  private void assertStateIs(Task.State state) {
+    TaskListenerIT.assertStateIs(forwarder.task, state);
+  }
+
+  private void assertStateIs(Task<?> task, Task.State state) {
+    TaskListenerIT.assertStateIs(task, state);
+  }
+
+  private void assertStateIsEventually(Task<?> task, Task.State state) throws InterruptedException {
+    long ms = 0;
+    assertThat(task).isNotNull();
+    while (!task.getState().equals(state)) {
+      assertThat(ms++).isLessThan(TIMEOUT);
+      TimeUnit.MILLISECONDS.sleep(1);
+    }
+  }
+}
diff --git a/javatests/com/google/gerrit/entities/converter/BUILD b/javatests/com/google/gerrit/entities/converter/BUILD
index 0ca9478..804397b 100644
--- a/javatests/com/google/gerrit/entities/converter/BUILD
+++ b/javatests/com/google/gerrit/entities/converter/BUILD
@@ -4,16 +4,19 @@
     name = "proto_converter_tests",
     srcs = glob(["*.java"]),
     deps = [
+        "//java/com/google/gerrit/common:annotations",
         "//java/com/google/gerrit/entities",
         "//java/com/google/gerrit/extensions:api",
         "//java/com/google/gerrit/proto/testing",
         "//java/com/google/gerrit/server",
         "//lib:guava",
+        "//lib:guava-testlib",
         "//lib:jgit",
         "//lib:protobuf",
         "//lib/guice",
         "//lib/truth",
         "//lib/truth:truth-proto-extension",
         "//proto:entities_java_proto",
+        "@commons-lang3//jar",
     ],
 )
diff --git a/javatests/com/google/gerrit/entities/converter/SafeProtoConverterTest.java b/javatests/com/google/gerrit/entities/converter/SafeProtoConverterTest.java
new file mode 100644
index 0000000..eb69d53
--- /dev/null
+++ b/javatests/com/google/gerrit/entities/converter/SafeProtoConverterTest.java
@@ -0,0 +1,286 @@
+package com.google.gerrit.entities.converter;
+
+import static com.google.common.collect.ImmutableList.toImmutableList;
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.extensions.proto.ProtoTruth.assertThat;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.primitives.Primitives;
+import com.google.common.reflect.ClassPath;
+import com.google.common.reflect.ClassPath.ClassInfo;
+import com.google.common.testing.ArbitraryInstances;
+import com.google.gerrit.common.ConvertibleToProto;
+import com.google.gerrit.common.Nullable;
+import com.google.protobuf.Descriptors.FieldDescriptor;
+import com.google.protobuf.Message;
+import com.google.protobuf.MessageLite;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.sql.Timestamp;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Stream;
+import javax.annotation.Nonnull;
+import org.apache.commons.lang3.builder.EqualsBuilder;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameter;
+import org.junit.runners.Parameterized.Parameters;
+import org.junit.runners.Suite;
+
+@RunWith(Suite.class)
+@Suite.SuiteClasses({
+  SafeProtoConverterTest.ListSafeProtoConverterTest.class, //
+  SafeProtoConverterTest.PerTypeSafeProtoConverterTest.class, //
+})
+public class SafeProtoConverterTest {
+  public static class ListSafeProtoConverterTest {
+    @Test
+    public void areAllConvertersEnums() throws Exception {
+      Stream<? extends Class<?>> safeConverters =
+          ClassPath.from(ClassLoader.getSystemClassLoader()).getAllClasses().stream()
+              .filter(type -> type.getPackageName().contains("gerrit"))
+              .map(ClassInfo::load)
+              .filter(SafeProtoConverter.class::isAssignableFrom)
+              .filter(clz -> !SafeProtoConverter.class.equals(clz));
+      // Safe converters must be enums. See also `isConverterAValidEnum` test below.
+      assertThat(safeConverters.allMatch(Class::isEnum)).isTrue();
+    }
+  }
+
+  @RunWith(Parameterized.class)
+  public static class PerTypeSafeProtoConverterTest {
+    @Parameter(0)
+    public SafeProtoConverter<Message, Object> converter;
+
+    @Parameter(1)
+    public String converterName;
+
+    @Parameters(name = "PerTypeSafeProtoConverterTest${1}")
+    public static ImmutableList<Object[]> listSafeConverters() throws Exception {
+      return ClassPath.from(ClassLoader.getSystemClassLoader()).getAllClasses().stream()
+          .filter(type -> type.getPackageName().contains("gerrit"))
+          .map(ClassInfo::load)
+          .filter(SafeProtoConverter.class::isAssignableFrom)
+          .filter(clz -> !SafeProtoConverter.class.equals(clz))
+          .filter(Class::isEnum)
+          .map(clz -> (SafeProtoConverter<Message, Object>) clz.getEnumConstants()[0])
+          .map(clz -> new Object[] {clz, clz.getClass().getSimpleName()})
+          .collect(toImmutableList());
+    }
+
+    /**
+     * For rising visibility, all Java Entity classes which have a {@link SafeProtoConverter}, must
+     * be annotated with {@link ConvertibleToProto}.
+     */
+    @Test
+    public void isJavaClassMarkedAsConvertibleToProto() {
+      assertThat(converter.getEntityClass().getDeclaredAnnotation(ConvertibleToProto.class))
+          .isNotNull();
+    }
+
+    /**
+     * All {@link SafeProtoConverter} implementations must be enums with a single instance. Please
+     * prefer descriptive enum and instance names, such as {@code
+     * MyTypeConverter::MY_TYPE_CONVERTER}.
+     */
+    @Test
+    public void isConverterAValidEnum() {
+      assertThat(converter.getClass().isEnum()).isTrue();
+      assertThat(converter.getClass().getEnumConstants().length).isEqualTo(1);
+    }
+
+    /**
+     * If this test fails, it's likely that you added a field to a Java class that has a {@link
+     * SafeProtoConverter} set, or that you have changed the default value for such a field. Please
+     * update the corresponding proto accordingly.
+     */
+    @Test
+    public void javaDefaultsKeptOnDoubleConversion() {
+      Object orig;
+      try {
+        orig = buildObjectWithFullFieldsOrThrow(converter.getEntityClass());
+      } catch (Exception e) {
+        throw new IllegalStateException(
+            String.format(
+                "Failed to build object for type %s, this likely means the buildObjectWithFullFieldsOrThrow should be adapted.",
+                converter.getEntityClass().getName()),
+            e);
+      }
+      Object res = converter.fromProto(converter.toProto(converter.getEntityClass().cast(orig)));
+      assertThat(orig).isEqualTo(res);
+      // If this assertion fails, it's likely that you forgot to update the `equals` method to
+      // include your new field.
+      assertThat(EqualsBuilder.reflectionEquals(orig, res)).isTrue();
+    }
+
+    /**
+     * If this test fails, it's likely that you added a field to a proto that has a {@link
+     * SafeProtoConverter} set, or that you have changed the default value for such a field. Please
+     * update the corresponding Java class accordingly.
+     */
+    @Test
+    public void protoDefaultsKeptOnDoubleConversion() {
+      Message defaultInstance = getProtoDefaultInstance(converter.getProtoClass());
+      Message preFilled = explicitlyFillProtoDefaults(defaultInstance);
+      Message resFromDefault =
+          converter.toProto(converter.fromProto(converter.getProtoClass().cast(preFilled)));
+      Message resFromPrefilled =
+          converter.toProto(converter.fromProto(converter.getProtoClass().cast(preFilled)));
+      assertThat(resFromDefault).isEqualTo(preFilled);
+      assertThat(resFromPrefilled).isEqualTo(preFilled);
+    }
+
+    @Nullable
+    private static Object buildObjectWithFullFieldsOrThrow(Class<?> clz) throws Exception {
+      if (clz == null) {
+        return null;
+      }
+      Object obj = construct(clz);
+      if (isSimple(clz)) {
+        return obj;
+      }
+      for (Field field : clz.getDeclaredFields()) {
+        if (Modifier.isStatic(field.getModifiers())) {
+          continue;
+        }
+        Class<?> parameterizedType = getParameterizedType(field);
+        if (!field.getType().isArray()
+            && !Map.class.isAssignableFrom(field.getType())
+            && !Collection.class.isAssignableFrom(field.getType())) {
+          if (!field.trySetAccessible()) {
+            return null;
+          }
+          field.set(obj, buildObjectWithFullFieldsOrThrow(field.getType()));
+        } else if (Collection.class.isAssignableFrom(field.getType())
+            && parameterizedType != null) {
+          field.set(obj, ImmutableList.of(buildObjectWithFullFieldsOrThrow(parameterizedType)));
+        }
+      }
+      return obj;
+    }
+
+    /**
+     * AutoValue annotations are not retained on runtime. We can only find out if a class is an
+     * AutoValue, by trying to load the expected AutoValue class.
+     *
+     * <p>For the class {@code package.Clz}, the AutoValue class name is {@code
+     * package.AutoValue_Clz}, for {@code package.Enclosing$Clz}, it is {@code
+     * package.AutoValue_Enclosing_Clz}
+     */
+    static Optional<Class<?>> toRepresentingAutoValueClass(Class<?> clz) {
+      String origClzName = clz.getName();
+      String autoValueClzName =
+          origClzName.substring(0, origClzName.lastIndexOf("."))
+              + ".AutoValue_"
+              + origClzName.substring(origClzName.lastIndexOf(".") + 1);
+      autoValueClzName = autoValueClzName.replace('$', '_');
+      try {
+        return Optional.of(clz.getClassLoader().loadClass(autoValueClzName));
+      } catch (Exception e) {
+        return Optional.empty();
+      }
+    }
+
+    @Nullable
+    private static Class<?> getParameterizedType(Field field) {
+      if (!Collection.class.isAssignableFrom(field.getType())) {
+        return null;
+      }
+      Type genericType = field.getGenericType();
+      if (genericType instanceof ParameterizedType) {
+        return (Class<?>) ((ParameterizedType) genericType).getActualTypeArguments()[0];
+      }
+      return null;
+    }
+
+    @Nonnull
+    static Object construct(@Nonnull Class<?> clz) {
+      try {
+        Object arbitrary = ArbitraryInstances.get(clz);
+        if (arbitrary != null) {
+          return arbitrary;
+        }
+        Optional<Class<?>> optionalAutoValueRepresentation = toRepresentingAutoValueClass(clz);
+        if (optionalAutoValueRepresentation.isPresent()) {
+          return construct(optionalAutoValueRepresentation.get());
+        }
+        Constructor<?> constructor =
+            Arrays.stream(clz.getDeclaredConstructors())
+                // Filter out copy constructors
+                .filter(
+                    c ->
+                        c.getParameterCount() != 1
+                            || !c.getParameterTypes()[0].isAssignableFrom(clz))
+                // Filter out private constructors which cannot be set accessible.
+                .filter(c -> c.canAccess(null) || c.trySetAccessible())
+                .min(Comparator.comparingInt(Constructor::getParameterCount))
+                .get();
+        List<Object> args = new ArrayList<>();
+        for (Class<?> f : constructor.getParameterTypes()) {
+          args.add(construct(f));
+        }
+        return constructor.newInstance(args.toArray());
+      } catch (Exception e) {
+        throw new IllegalStateException("Failed to construct class " + clz.getName(), e);
+      }
+    }
+
+    static boolean isSimple(Class<?> c) {
+      return c.isPrimitive()
+          || c.isEnum()
+          || Primitives.isWrapperType(c)
+          || String.class.isAssignableFrom(c)
+          || Timestamp.class.isAssignableFrom(c);
+    }
+
+    /**
+     * Returns the default instance for the given MessageLite class, if it has the {@code
+     * getDefaultInstance} static method.
+     *
+     * @param type the protobuf message class
+     * @throws IllegalArgumentException if the given class doesn't have the static {@code
+     *     getDefaultInstance} method
+     */
+    public static <T extends MessageLite> T getProtoDefaultInstance(Class<T> type) {
+      try {
+        return type.cast(type.getMethod("getDefaultInstance").invoke(null));
+      } catch (ReflectiveOperationException | ClassCastException e) {
+        throw new IllegalStateException("Cannot get default instance for " + type, e);
+      }
+    }
+
+    private static Message explicitlyFillProtoDefaults(Message defaultInstance) {
+      Message.Builder res = defaultInstance.toBuilder();
+      for (FieldDescriptor f : defaultInstance.getDescriptorForType().getFields()) {
+        try {
+          if (f.getType().equals(FieldDescriptor.Type.MESSAGE)) {
+            if (f.isRepeated()) {
+              res.addRepeatedField(
+                  f,
+                  explicitlyFillProtoDefaults(
+                      explicitlyFillProtoDefaults(
+                          getProtoDefaultInstance(res.newBuilderForField(f).build().getClass()))));
+            } else {
+              res.setField(f, explicitlyFillProtoDefaults((Message) defaultInstance.getField(f)));
+            }
+          } else {
+            res.setField(f, defaultInstance.getField(f));
+          }
+        } catch (Exception e) {
+          throw new IllegalStateException("Failed to fill default instance for " + f.getName(), e);
+        }
+      }
+      return res.build();
+    }
+  }
+}
diff --git a/lib/highlightjs/BUILD b/lib/highlightjs/BUILD
index 4105d85..d55a273 100644
--- a/lib/highlightjs/BUILD
+++ b/lib/highlightjs/BUILD
@@ -12,6 +12,7 @@
     srcs = [
         "@ui_npm//highlight.js",
         "@ui_npm//highlightjs-closure-templates",
+        "@ui_npm//highlightjs-epp",
         "@ui_npm//highlightjs-structured-text",
     ],
     config_file = "rollup.config.js",
diff --git a/lib/highlightjs/index.js b/lib/highlightjs/index.js
index c2d048d..811dec7 100644
--- a/lib/highlightjs/index.js
+++ b/lib/highlightjs/index.js
@@ -17,9 +17,11 @@
 
 import hljs from 'highlight.js';
 import soy from 'highlightjs-closure-templates';
+import epp from 'highlightjs-epp';
 import iecst from 'highlightjs-structured-text';
 
 hljs.registerLanguage('soy', soy);
+hljs.registerLanguage('epp', epp);
 hljs.registerLanguage('iecst', iecst);
 
 export default hljs;
diff --git a/lib/nongoogle_test.sh b/lib/nongoogle_test.sh
index 6865340..37cee04 100755
--- a/lib/nongoogle_test.sh
+++ b/lib/nongoogle_test.sh
@@ -11,6 +11,11 @@
 grep 'name = "[^"]*"' ${bzl} | sed 's|^[^"]*"||g;s|".*$||g' | sort > $TMP/names
 
 cat << EOF > $TMP/want
+auto-common
+auto-factory
+auto-service-annotations
+auto-value
+auto-value-annotations
 cglib-3_2
 commons-io
 dropwizard-core
@@ -20,6 +25,7 @@
 flogger-google-extensions
 flogger-log4j-backend
 flogger-system-backend
+gson
 guava
 guava-testlib
 guice-assistedinject
diff --git a/modules/jgit b/modules/jgit
index c0b415f..d06722a 160000
--- a/modules/jgit
+++ b/modules/jgit
@@ -1 +1 @@
-Subproject commit c0b415fb028b4c1f29b6df749323bbb11599495d
+Subproject commit d06722a15998eeee04cfefd7c3c7e79fe67f1494
diff --git a/polygerrit-ui/app/api/embed.ts b/polygerrit-ui/app/api/embed.ts
index 2faeeda..d6425be 100644
--- a/polygerrit-ui/app/api/embed.ts
+++ b/polygerrit-ui/app/api/embed.ts
@@ -45,6 +45,7 @@
 /** <gr-textarea> event when showing a hint */
 export declare interface HintShownEventDetail {
   hint: string;
+  oldValue: string;
 }
 
 /** <gr-textarea> event when a hint was dismissed */
diff --git a/polygerrit-ui/app/api/suggestions.ts b/polygerrit-ui/app/api/suggestions.ts
index c3089a9..b952180 100644
--- a/polygerrit-ui/app/api/suggestions.ts
+++ b/polygerrit-ui/app/api/suggestions.ts
@@ -72,6 +72,7 @@
 export declare interface AutocompleteCommentResponse {
   responseCode: ResponseCode;
   completion?: string;
+  modelVersion?: string;
 }
 
 export declare interface SuggestCodeResponse {
diff --git a/polygerrit-ui/app/constants/constants.ts b/polygerrit-ui/app/constants/constants.ts
index 0fa58f4..b21663a 100644
--- a/polygerrit-ui/app/constants/constants.ts
+++ b/polygerrit-ui/app/constants/constants.ts
@@ -264,6 +264,7 @@
     default_base_for_merges: DefaultBase.AUTO_MERGE,
     allow_browser_notifications: false,
     allow_suggest_code_while_commenting: true,
+    allow_autocompleting_comments: true,
     diff_page_sidebar: 'NONE',
   };
 }
diff --git a/polygerrit-ui/app/constants/reporting.ts b/polygerrit-ui/app/constants/reporting.ts
index 37a17ba..643f8aa 100644
--- a/polygerrit-ui/app/constants/reporting.ts
+++ b/polygerrit-ui/app/constants/reporting.ts
@@ -102,6 +102,8 @@
   APPLY_FIX_LOAD = 'ApplyFixLoad',
   // Time to copy target to clipboard
   COPY_TO_CLIPBOARD = 'CopyToClipboard',
+  // Time to autocomplete a comment
+  COMMENT_COMPLETION = 'CommentCompletion',
 }
 
 export enum Interaction {
@@ -156,4 +158,9 @@
   // The very first reporting event with `ChangeId` set when visiting a change
   // related page. Can be used as a starting point for user journeys.
   CHANGE_ID_CHANGED = 'change-id-changed',
+
+  COMMENT_COMPLETION_SUGGESTION_SHOWN = 'comment-completion-suggestion-shown',
+  COMMENT_COMPLETION_SUGGESTION_ACCEPTED = 'comment-completion-suggestion-accepted',
+  COMMENT_COMPLETION_SAVE_DRAFT = 'comment-completion-save-draft',
+  COMMENT_COMPLETION_SUGGESTION_FETCHED = 'comment-completion-suggestion-fetched',
 }
diff --git a/polygerrit-ui/app/elements/admin/gr-repo/gr-repo.ts b/polygerrit-ui/app/elements/admin/gr-repo/gr-repo.ts
index 4e8841e..2251321 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo/gr-repo.ts
+++ b/polygerrit-ui/app/elements/admin/gr-repo/gr-repo.ts
@@ -815,7 +815,7 @@
         config.max_object_size_limit.configured_value = '';
       }
       this.repoConfig = config;
-      this.originalConfig = deepClone(config) as ConfigInfo;
+      this.originalConfig = deepClone<ConfigInfo>(config);
       this.loading = false;
     };
     promises.push(repoConfigHelper());
@@ -920,7 +920,7 @@
       this.repo,
       this.formatRepoConfigForSave(this.repoConfig)
     );
-    this.originalConfig = deepClone(this.repoConfig) as ConfigInfo;
+    this.originalConfig = deepClone<ConfigInfo>(this.repoConfig);
     this.pluginConfigChanged = false;
     return;
   }
diff --git a/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.ts b/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.ts
index 50ec339..836d86a 100644
--- a/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-actions/gr-change-actions.ts
@@ -485,7 +485,7 @@
 
   @state() pluginsLoaded = false;
 
-  @state() threadsWithSuggestions?: CommentThread[];
+  @state() threadsWithUnappliedSuggestions?: CommentThread[];
 
   private readonly restApiService = getAppContext().restApiService;
 
@@ -579,8 +579,8 @@
     );
     subscribe(
       this,
-      () => this.getCommentsModel().threadsWithSuggestions$,
-      x => (this.threadsWithSuggestions = x)
+      () => this.getCommentsModel().threadsWithUnappliedSuggestions$,
+      x => (this.threadsWithUnappliedSuggestions = x)
     );
   }
 
@@ -820,11 +820,11 @@
           <div class="header" slot="header">Publish Change Edit</div>
           <div class="main" slot="main">
             ${when(
-              this.numberOfThreadsWithSuggestions() > 0,
+              this.numberOfThreadsWithUnappliedSuggestions() > 0,
               () => html`<p class="info">
                 <gr-icon id="icon" icon="info" small></gr-icon>
-                Heads Up! ${this.numberOfThreadsWithSuggestions()} comments have
-                suggestions you can apply before publishing
+                Heads Up! ${this.numberOfThreadsWithUnappliedSuggestions()}
+                comments have suggestions you can apply before publishing
               </p>`
             )}
             Do you really want to publish the edit?
@@ -2105,8 +2105,16 @@
   }
 
   private handlePublishEditTap() {
-    assertIsDefined(this.confirmPublishEditDialog, 'confirmPublishEditDialog');
-    this.showActionDialog(this.confirmPublishEditDialog);
+    if (this.numberOfThreadsWithUnappliedSuggestions() > 0) {
+      assertIsDefined(
+        this.confirmPublishEditDialog,
+        'confirmPublishEditDialog'
+      );
+      this.showActionDialog(this.confirmPublishEditDialog);
+    } else {
+      // Skip confirmation dialog and publish immediately.
+      this.handlePublishEditConfirm();
+    }
   }
 
   private handleRebaseEditTap() {
@@ -2264,9 +2272,9 @@
     fireNoBubbleNoCompose(this, 'stop-edit-tap', {});
   }
 
-  private numberOfThreadsWithSuggestions() {
-    if (!this.threadsWithSuggestions) return 0;
-    return this.threadsWithSuggestions.length;
+  private numberOfThreadsWithUnappliedSuggestions() {
+    if (!this.threadsWithUnappliedSuggestions) return 0;
+    return this.threadsWithUnappliedSuggestions.length;
   }
 }
 
diff --git a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
index b2b045a..c76e928 100644
--- a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
+++ b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
@@ -123,7 +123,7 @@
 import {Key, Modifier, whenVisible} from '../../../utils/dom-util';
 import {GrThreadList} from '../gr-thread-list/gr-thread-list';
 import {userModelToken} from '../../../models/user/user-model';
-import {accountsModelToken} from '../../../models/accounts-model/accounts-model';
+import {accountsModelToken} from '../../../models/accounts/accounts-model';
 import {pluginLoaderToken} from '../../shared/gr-js-api-interface/gr-plugin-loader';
 import {modalStyles} from '../../../styles/gr-modal-styles';
 import {ironAnnouncerRequestAvailability} from '../../polymer-util';
diff --git a/polygerrit-ui/app/elements/change/gr-revision-parents/gr-revision-parents.ts b/polygerrit-ui/app/elements/change/gr-revision-parents/gr-revision-parents.ts
index 9cf5423..2dbbd26 100644
--- a/polygerrit-ui/app/elements/change/gr-revision-parents/gr-revision-parents.ts
+++ b/polygerrit-ui/app/elements/change/gr-revision-parents/gr-revision-parents.ts
@@ -3,6 +3,8 @@
  * Copyright 2023 Google LLC
  * SPDX-License-Identifier: Apache-2.0
  */
+import '../gr-commit-info/gr-commit-info';
+import '../../shared/gr-button/gr-button';
 import {customElement, state} from 'lit/decorators.js';
 import {css, html, HTMLTemplateResult, LitElement} from 'lit';
 import {resolve} from '../../../models/dependency';
diff --git a/polygerrit-ui/app/elements/change/gr-revision-parents/gr-revision-parents_test.ts b/polygerrit-ui/app/elements/change/gr-revision-parents/gr-revision-parents_test.ts
index b9aa63d..d3b46ff 100644
--- a/polygerrit-ui/app/elements/change/gr-revision-parents/gr-revision-parents_test.ts
+++ b/polygerrit-ui/app/elements/change/gr-revision-parents/gr-revision-parents_test.ts
@@ -167,7 +167,7 @@
        The diff below may not be meaningful and may<br/>
        even be hiding relevant changes.
        <a href="/Documentation/user-review-ui.html#hazardous-rebases">Learn more</a>
-       </p><p><gr-button link="">Show details</gr-button></p></div></div>`
+       </p><p><gr-button aria-disabled="false" link="" role="button" tabindex="0">Show details</gr-button></p></div></div>`
     );
   });
 
@@ -183,7 +183,7 @@
             The diff below may not be meaningful and may<br/>
             even be hiding relevant changes.
             <a href="/Documentation/user-review-ui.html#hazardous-rebases">Learn more</a>
-            </p><p><gr-button link="">Show details</gr-button></p></div></div>`
+            </p><p><gr-button aria-disabled="false" link="" role="button" tabindex="0">Show details</gr-button></p></div></div>`
     );
   });
 
@@ -235,7 +235,7 @@
        The diff below may not be meaningful and may<br/>
        even be hiding relevant changes.
        <a href="/Documentation/user-review-ui.html#hazardous-rebases">Learn more</a>
-       </p><p><gr-button link="">Show details</gr-button></p></div></div>`
+       </p><p><gr-button aria-disabled="false" link="" role="button" tabindex="0">Show details</gr-button></p></div></div>`
     );
   });
 });
diff --git a/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.ts b/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.ts
index e63ac8f..644871a4 100644
--- a/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.ts
+++ b/polygerrit-ui/app/elements/core/gr-account-dropdown/gr-account-dropdown.ts
@@ -32,6 +32,9 @@
   @property({type: Object})
   account?: AccountInfo;
 
+  @property({type: Boolean})
+  showMobile?: boolean;
+
   // Private but used in test
   @state()
   config?: ServerInfo;
@@ -45,6 +48,9 @@
   @state()
   private switchAccountUrl = '';
 
+  // private but used in test
+  @state() feedbackURL = '';
+
   // Private but used in test
   readonly getConfigModel = resolve(this, configModelToken);
 
@@ -56,6 +62,10 @@
       cfg => {
         this.config = cfg;
 
+        if (cfg?.gerrit?.report_bug_url) {
+          this.feedbackURL = cfg?.gerrit.report_bug_url;
+        }
+
         if (cfg && cfg.auth && cfg.auth.switch_account_url) {
           this.switchAccountUrl = cfg.auth.switch_account_url;
         } else {
@@ -103,7 +113,11 @@
       @tap-item-shortcuts=${this.handleShortcutsTap}
       .horizontalAlign=${'right'}
     >
-      <span ?hidden=${this.hasAvatars}>${this.accountName(this.account)}</span>
+      ${this.showMobile && !this.hasAvatars
+        ? html`<gr-icon icon="account_circle" filled></gr-icon>`
+        : html`<span ?hidden=${this.hasAvatars}
+            >${this.accountName(this.account)}</span
+          >`}
       <gr-avatar
         .account=${this.account}
         ?hidden=${!this.hasAvatars}
@@ -135,6 +149,15 @@
       const url = this.interpolateUrl(switchAccountUrl, replacements);
       links.push({name: 'Switch account', url, external: true});
     }
+    if (this.showMobile && this.feedbackURL) {
+      links.push({
+        name: 'Feedback',
+        id: 'feedback',
+        url: this.feedbackURL,
+        external: true,
+        target: '_blank',
+      });
+    }
     links.push({name: 'Sign out', id: 'signout', url: '/logout'});
     return links;
   }
diff --git a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.ts b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.ts
index ae59fb6..3be77db 100644
--- a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.ts
+++ b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header.ts
@@ -22,13 +22,14 @@
 import {getAppContext} from '../../../services/app-context';
 import {sharedStyles} from '../../../styles/shared-styles';
 import {LitElement, PropertyValues, html, css} from 'lit';
-import {customElement, property, state} from 'lit/decorators.js';
+import {customElement, property, query, state} from 'lit/decorators.js';
 import {fire} from '../../../utils/event-util';
 import {resolve} from '../../../models/dependency';
 import {configModelToken} from '../../../models/config/config-model';
 import {userModelToken} from '../../../models/user/user-model';
 import {pluginLoaderToken} from '../../shared/gr-js-api-interface/gr-plugin-loader';
 import {subscribe} from '../../lit/subscription-controller';
+import {ifDefined} from 'lit/directives/if-defined.js';
 
 type MainHeaderLink = RequireProperties<DropdownLink, 'url' | 'name'>;
 
@@ -104,6 +105,9 @@
   AuthType.CUSTOM_EXTENSION,
 ]);
 
+const REL_NOOPENER = 'noopener';
+const REL_EXTERNAL = 'external';
+
 declare global {
   interface HTMLElementTagNameMap {
     'gr-main-header': GrMainHeader;
@@ -149,6 +153,15 @@
   // private but used in test
   @state() feedbackURL = '';
 
+  @state() hamburgerClose? = false;
+
+  @query('.nav-sidebar') navSidebar?: HTMLDivElement;
+
+  @query('.modelBackground') modelBackground?: HTMLDivElement;
+
+  @query('.has-collapsible.active')
+  hasCollapsibleActive?: HTMLLIElement;
+
   private readonly restApiService = getAppContext().restApiService;
 
   private readonly getPluginLoader = resolve(this, pluginLoaderToken);
@@ -202,10 +215,29 @@
         :host {
           display: block;
         }
-        nav {
+        .hideOnDesktop {
+          display: none;
+        }
+
+        nav.hideOnMobile {
           align-items: center;
           display: flex;
         }
+        nav.hideOnMobile ul {
+          list-style: none;
+          padding-left: var(--spacing-l);
+        }
+        nav.hideOnMobile .links > li {
+          cursor: default;
+          display: inline-block;
+          padding: 0;
+          position: relative;
+        }
+
+        .mobileTitle {
+          display: none;
+        }
+
         .bigTitle {
           color: var(--header-text-color);
           font-size: var(--header-title-font-size);
@@ -215,7 +247,8 @@
         .bigTitle:hover {
           text-decoration: underline;
         }
-        .titleText {
+        .titleText,
+        .mobileTitleText {
           /* Vertical alignment of icons and text with just block/inline display is too troublesome. */
           display: flex;
           align-items: center;
@@ -239,16 +272,45 @@
           content: var(--header-title-content);
           white-space: nowrap;
         }
-        ul {
-          list-style: none;
-          padding-left: var(--spacing-l);
+
+        .mobileTitleText::before {
+          --icon-width: var(
+            --header-icon-width,
+            var(--header-mobile-icon-size, var(--header-icon-size, 0))
+          );
+          --icon-height: var(
+            --header-icon-height,
+            var(--header-mobile-icon-size, var(--header-icon-size, 0))
+          );
+          background-image: var(--header-mobile-icon, var(--header-icon));
+          background-size: var(--mobile-icon-width, var(--icon-width))
+            var(--mobile-icon-height, var(--icon-height));
+          background-repeat: no-repeat;
+          content: '';
+          /* Any direct child of a flex element implicitly has 'display: block', but let's make that explicit here. */
+          display: block;
+          width: var(--mobile-icon-width, var(--icon-width));
+          height: var(--mobile-icon-height, var(--icon-height));
+          /* If size or height are set, then use 'spacing-m', 0px otherwise. */
+          margin-right: clamp(
+            0px,
+            var(--mobile-icon-height, var(--icon-height)),
+            var(--spacing-m)
+          );
         }
-        .links > li {
-          cursor: default;
-          display: inline-block;
-          padding: 0;
-          position: relative;
+        .mobileTitleText::after {
+          /* The height will be determined by the line-height of the .bigTitle element. */
+          content: var(
+            --header-mobile-title-content,
+            var(--header-title-content)
+          );
+          white-space: nowrap;
+          text-overflow: ellipsis;
+          flex: 1;
+          overflow: hidden;
+          min-width: 0;
         }
+
         .linksTitle {
           display: inline-block;
           font-weight: var(--font-weight-bold);
@@ -264,7 +326,24 @@
           flex: 1;
           justify-content: flex-end;
         }
-        .rightItems gr-endpoint-decorator:not(:empty) {
+        .mobileRightItems {
+          align-items: center;
+          justify-content: flex-end;
+
+          display: inline-block;
+          vertical-align: middle;
+          cursor: pointer;
+          position: relative;
+          top: 0px;
+          right: 0px;
+          margin-right: 0;
+          margin-left: auto;
+          min-height: 50px;
+          padding-top: 12px;
+        }
+
+        .rightItems gr-endpoint-decorator:not(:empty),
+        .mobileRightItems gr-endpoint-decorator:not(:empty) {
           margin-left: var(--spacing-l);
         }
         gr-smart-search {
@@ -299,13 +378,17 @@
         }
         :host([loading]) .accountContainer,
         :host([loggedIn]) .loginButton,
-        :host([loggedIn]) .registerButton {
+        :host([loggedIn]) .registerButton,
+        :host([loggedIn]) .moreMenu {
           display: none;
         }
         :host([loggedIn]) .settingsButton,
         :host([loggedIn]) gr-account-dropdown {
           display: inline;
         }
+        :host:not([loggedIn]) .moreMenu {
+          display: inline;
+        }
         .accountContainer {
           flex: 0 0 auto;
           align-items: center;
@@ -363,7 +446,158 @@
             margin-left: var(--spacing-m) !important;
           }
           gr-dropdown {
-            padding: var(--spacing-m) 0 var(--spacing-m) var(--spacing-m);
+            padding: 0 var(--spacing-m);
+          }
+          .nav-sidebar {
+            background: var(--table-header-background-color);
+            width: 200px;
+            height: 100%;
+            display: block;
+            position: fixed;
+            left: -200px;
+            top: 0px;
+            transition: left 0.25s ease;
+            margin: 0;
+            border: 0;
+            overflow-y: auto;
+            overflow-x: hidden;
+            height: 100%;
+            margin-bottom: 15px 0;
+            box-shadow: 0 2px 5px 0 rgba(0, 0, 0, 0.26);
+            border-radius: 3px;
+            z-index: 2;
+          }
+          .nav-sidebar.visible {
+            left: 0px;
+            transition: left 0.25s ease;
+            width: 80%;
+            z-index: 200;
+          }
+          .mobileTitle {
+            position: relative;
+            display: block;
+            top: 10px;
+            font-size: 20px;
+            left: 100px;
+            right: 100px;
+            text-align: center;
+            text-overflow: ellipsis;
+            overflow: hidden;
+            width: 50%;
+          }
+          .nav-header {
+            display: flex;
+          }
+          .hamburger {
+            display: inline-block;
+            vertical-align: middle;
+            height: 50px;
+            cursor: pointer;
+            margin: 0;
+            position: absolute;
+            top: 0;
+            left: 0;
+            padding: 12px;
+            z-index: 200;
+          }
+          .nav-sidebar ul {
+            list-style-type: none;
+            margin: 0;
+            padding: 0;
+            display: block;
+            padding-top: 50px;
+          }
+          .nav-sidebar li {
+            list-style-type: none;
+            margin: 0;
+            padding: 0;
+            display: inline-block;
+            position: relative;
+            font-size: 14;
+            color: var(--primary-text-color);
+            display: block;
+          }
+          .cover {
+            background: rgba(0, 0, 0, 0.5);
+            position: fixed;
+            top: 0;
+            bottom: 0;
+            left: 0;
+            right: 0;
+            overflow: none;
+            z-index: 199;
+          }
+          .hideOnDesktop {
+            display: block;
+          }
+          nav.hideOnMobile {
+            display: none;
+          }
+          .nav-sidebar .menu ul {
+            list-style-type: none;
+            margin: 0;
+            padding: 0;
+            display: block;
+            padding-top: 50px;
+          }
+          .nav-sidebar .menu li {
+            list-style-type: none;
+            margin: 0;
+            padding: 0;
+            display: inline-block;
+            position: relative;
+            font-size: 14;
+            color: var(--primary-text-color);
+            display: block;
+          }
+          .nav-sidebar .menu li a {
+            padding: 15px 20px;
+            font-size: 14;
+            outline: 0;
+            display: block;
+            color: var(--primary-text-color);
+            font-weight: 600;
+          }
+          .nav-sidebar .menu li.active ul.dropdown {
+            display: block;
+          }
+          .nav-sidebar .menu li ul.dropdown {
+            position: absolute;
+            display: none;
+            width: 100%;
+            box-shadow: 0 2px 5px 0 rgba(0, 0, 0, 0.26);
+            padding-top: 0;
+            position: relative;
+          }
+          .nav-sidebar .menu li ul.dropdown li {
+            display: block;
+            list-style-type: none;
+          }
+          .nav-sidebar .menu li ul.dropdown li a {
+            padding: 15px 20px;
+            font-size: 15px;
+            display: block;
+            font-weight: 400;
+            border-bottom: none;
+            padding: 10px 10px 10px 30px;
+          }
+          .nav-sidebar .menu li ul.dropdown li:last-child a {
+            border-bottom: none;
+          }
+          .nav-sidebar .menu a {
+            text-decoration: none;
+          }
+          .nav-sidebar .menu li.active:first-child a {
+            border-radius: 3px 0 0 3px;
+            border-radius: 0;
+          }
+          .nav-sidebar .menu li ul.dropdown li.active:first-child a {
+            border-radius: 0;
+          }
+          .arrow-down {
+            position: absolute;
+            top: 10px;
+            right: 10px;
           }
         }
       `,
@@ -371,35 +605,130 @@
   }
 
   override render() {
+    return html` ${this.renderDesktop()} ${this.renderMobile()} `;
+  }
+
+  private renderDesktop() {
     return html`
-  <nav>
-    <a href=${`//${window.location.host}${getBaseUrl()}/`} class="bigTitle">
-      <gr-endpoint-decorator name="header-title">
-        <div class="titleText"></div>
-      </gr-endpoint-decorator>
-    </a>
-    <ul class="links">
-      ${this.computeLinks(this.userLinks, this.adminLinks, this.topMenus).map(
-        linkGroup => this.renderLinkGroup(linkGroup)
-      )}
-    </ul>
-    <div class="rightItems">
-      <gr-endpoint-decorator
-        class="hideOnMobile"
-        name="header-small-banner"
-      ></gr-endpoint-decorator>
-      <gr-smart-search id="search"></gr-smart-search>
-      <gr-endpoint-decorator
-        class="hideOnMobile"
-        name="header-top-right"
-      ></gr-endpoint-decorator>
-      <gr-endpoint-decorator class="feedbackButton" name="header-feedback">
-        ${this.renderFeedback()}
-      </gr-endpoint-decorator>
-      </div>
-      ${this.renderAccount()}
-    </div>
-  </nav>
+      <nav class="hideOnMobile">
+        <a href=${`//${window.location.host}${getBaseUrl()}/`} class="bigTitle">
+          <gr-endpoint-decorator name="header-title">
+            <div class="titleText"></div>
+          </gr-endpoint-decorator>
+        </a>
+        <ul class="links">
+          ${this.computeLinks(
+            this.userLinks,
+            this.adminLinks,
+            this.topMenus
+          ).map(linkGroup => this.renderLinkGroup(linkGroup))}
+        </ul>
+        <div class="rightItems">
+          <gr-endpoint-decorator
+            class="hideOnMobile"
+            name="header-small-banner"
+          ></gr-endpoint-decorator>
+          <gr-smart-search id="search"></gr-smart-search>
+          <gr-endpoint-decorator
+            class="hideOnMobile"
+            name="header-top-right"
+          ></gr-endpoint-decorator>
+          <gr-endpoint-decorator class="feedbackButton" name="header-feedback">
+            ${this.renderFeedback()}
+          </gr-endpoint-decorator>
+          </div>
+          ${this.renderAccount()}
+        </div>
+      </nav>
+    `;
+  }
+
+  private renderMobile() {
+    const moreMenu: MainHeaderLink[] = [
+      {
+        name: this.registerText,
+        url: this.registerURL,
+      },
+      {
+        name: this.loginText,
+        url: this.loginUrl,
+      },
+    ];
+    if (!this.registerURL) {
+      moreMenu.shift();
+    }
+    if (this.feedbackURL) {
+      moreMenu.push({
+        name: 'Feedback',
+        url: this.feedbackURL,
+        external: true,
+        target: '_blank',
+      });
+    }
+
+    return html`
+      <nav class="hideOnDesktop">
+        <div class="nav-sidebar">
+          <ul class="menu">
+            ${this.computeLinks(
+              this.userLinks,
+              this.adminLinks,
+              this.topMenus
+            ).map(linkGroup => this.renderLinkGroupMobile(linkGroup))}
+          </ul>
+        </div>
+        <div class="nav-header">
+          <a
+            class="hamburger"
+            href=""
+            title="Hamburger"
+            aria-label="${!this.hamburgerClose ? 'Open' : 'Close'} hamburger"
+            role="button"
+            @click=${() => {
+              this.handleSidebar();
+            }}
+          >
+            ${!this.hamburgerClose
+              ? html`<gr-icon icon="menu" filled></gr-icon>`
+              : html`<gr-icon icon="menu_open" filled></gr-icon>`}
+          </a>
+          <a
+            href=${`//${window.location.host}${getBaseUrl()}/`}
+            class="mobileTitle bigTitle"
+          >
+            <gr-endpoint-decorator name="header-mobile-title">
+              <div class="mobileTitleText"></div>
+            </gr-endpoint-decorator>
+          </a>
+          <div class="mobileRightItems">
+            <a
+              class="searchButton"
+              title="Search"
+              @click=${(e: Event) => {
+                this.onMobileSearchTap(e);
+              }}
+              role="button"
+              aria-label=${this.mobileSearchHidden
+                ? 'Show Searchbar'
+                : 'Hide Searchbar'}
+            >
+              <gr-icon icon="search" filled></gr-icon>
+            </a>
+            <gr-dropdown
+              class="moreMenu"
+              link=""
+              .items=${moreMenu}
+              horizontal-align="center"
+            >
+              <span class="linksTitle">
+                <gr-icon icon="more_horiz" filled></gr-icon>
+              </span>
+            </gr-dropdown>
+            ${this.renderAccountDropdown(true)}
+          </div>
+        </div>
+      </nav>
+      <div class="modelBackground" @click=${() => this.handleSidebar()}></div>
     `;
   }
 
@@ -420,6 +749,41 @@
     `;
   }
 
+  private renderLinkGroupMobile(linkGroup: MainHeaderLinkGroup) {
+    return html`
+      <li class="has-collapsible" @click=${this.handleCollapsible}>
+        <a class="main" href="" data-title=${linkGroup.title}
+          >${linkGroup.title}<gr-icon
+            icon="arrow_drop_down"
+            class="arrow-down"
+          ></gr-icon
+        ></a>
+        <ul class="dropdown">
+          ${linkGroup.links.map(link => this.renderLinkMobile(link))}
+        </ul>
+      </li>
+    `;
+  }
+
+  private renderLinkMobile(link: DropdownLink) {
+    return html`
+      <li tabindex="-1">
+        <span ?hidden=${!!link.url} tabindex="-1">${link.name}</span>
+        <a
+          class="itemAction"
+          href=${this.computeLinkURL(link)}
+          ?download=${!!link.download}
+          rel=${ifDefined(this.computeLinkRel(link) ?? undefined)}
+          target=${ifDefined(link.target ?? undefined)}
+          ?hidden=${!link.url}
+          tabindex="-1"
+          @click=${() => this.handleSidebar()}
+          >${link.name}</a
+        >
+      </li>
+    `;
+  }
+
   private renderFeedback() {
     if (!this.feedbackURL) return;
 
@@ -483,11 +847,14 @@
     `;
   }
 
-  private renderAccountDropdown() {
+  private renderAccountDropdown(showOnMobile?: boolean) {
     if (!this.account) return;
 
     return html`
-      <gr-account-dropdown .account=${this.account}></gr-account-dropdown>
+      <gr-account-dropdown
+        .account=${this.account}
+        ?showMobile=${showOnMobile}
+      ></gr-account-dropdown>
     `;
   }
 
@@ -533,7 +900,6 @@
       links.push({
         title: 'Documentation',
         links: docLinks,
-        class: 'hideOnMobile',
       });
     }
     links.push({
@@ -637,4 +1003,96 @@
     e.stopPropagation();
     fire(this, 'mobile-search', {});
   }
+
+  /**
+   * Build a URL for the given host and path. The base URL will be only added,
+   * if it is not already included in the path.
+   *
+   * TODO: Move to util handler to remove duplication.
+   * @return The scheme-relative URL.
+   */
+  private computeURLHelper(host: string, path: string) {
+    const base = path.startsWith(getBaseUrl()) ? '' : getBaseUrl();
+    return '//' + host + base + path;
+  }
+
+  /**
+   * Build a scheme-relative URL for the current host. Will include the base
+   * URL if one is present. Note: the URL will be scheme-relative but absolute
+   * with regard to the host.
+   *
+   * TODO: Move to util handler to remove duplication.
+   * @param path The path for the URL.
+   * @return The scheme-relative URL.
+   */
+  private computeRelativeURL(path: string) {
+    const host = window.location.host;
+    return this.computeURLHelper(host, path);
+  }
+
+  /**
+   * Compute the URL for a link object.
+   *
+   * Private but used in tests.
+   *
+   * TODO: Move to util handler to remove duplication.
+   */
+  private computeLinkURL(link: DropdownLink) {
+    if (typeof link.url === 'undefined') {
+      return '';
+    }
+    if (link.target || !link.url.startsWith('/')) {
+      return link.url;
+    }
+    return this.computeRelativeURL(link.url);
+  }
+
+  /**
+   * Compute the value for the rel attribute of an anchor for the given link
+   * object. If the link has a target value, then the rel must be "noopener"
+   * for security reasons.
+   * Private but used in tests.
+   *
+   * TODO: Move to util handler to remove duplication.
+   */
+  private computeLinkRel(link: DropdownLink) {
+    // Note: noopener takes precedence over external.
+    if (link.target) {
+      return REL_NOOPENER;
+    }
+    if (link.external) {
+      return REL_EXTERNAL;
+    }
+    return null;
+  }
+
+  private handleCollapsible(e: MouseEvent) {
+    const target = e.target as HTMLSpanElement;
+    if (target.hasAttribute('data-title')) {
+      if (target.parentElement?.classList.contains('active')) {
+        target.parentElement.classList.remove('active');
+      } else {
+        if (this.hasCollapsibleActive) {
+          this.hasCollapsibleActive.classList.remove('active');
+        }
+        target.parentElement?.classList.toggle('active');
+      }
+    }
+  }
+
+  private handleSidebar() {
+    this.navSidebar?.classList.toggle('visible');
+    if (!this.modelBackground?.classList.contains('cover')) {
+      if (document.getElementsByTagName('html')) {
+        document.getElementsByTagName('html')[0].style.overflow = 'hidden';
+      }
+    } else {
+      if (document.getElementsByTagName('html')) {
+        document.getElementsByTagName('html')[0].style.overflow = '';
+      }
+    }
+    this.modelBackground?.classList.toggle('cover');
+    this.hasCollapsibleActive?.classList.remove('active');
+    this.hamburgerClose = !this.hamburgerClose;
+  }
 }
diff --git a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.ts b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.ts
index 40430fb..b4a0600 100644
--- a/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.ts
+++ b/polygerrit-ui/app/elements/core/gr-main-header/gr-main-header_test.ts
@@ -39,7 +39,7 @@
     assert.shadowDom.equal(
       element,
       /* HTML */ `
-        <nav>
+        <nav class="hideOnMobile">
           <a class="bigTitle" href="//localhost:9876/">
             <gr-endpoint-decorator name="header-title">
               <div class="titleText"></div>
@@ -51,7 +51,7 @@
                 <span class="linksTitle" id="Changes"> Changes </span>
               </gr-dropdown>
             </li>
-            <li class="hideOnMobile">
+            <li>
               <gr-dropdown down-arrow="" horizontal-align="left" link="">
                 <span class="linksTitle" id="Documentation">Documentation</span>
               </gr-dropdown>
@@ -101,6 +101,169 @@
             </a>
           </div>
         </nav>
+        <nav class="hideOnDesktop">
+          <div class="nav-sidebar">
+            <ul class="menu">
+              <li class="has-collapsible">
+                <a class="main" data-title="Changes" href="">
+                  Changes
+                  <gr-icon class="arrow-down" icon="arrow_drop_down"> </gr-icon>
+                </a>
+                <ul class="dropdown">
+                  <li tabindex="-1">
+                    <span hidden="" tabindex="-1"> Open </span>
+                    <a
+                      class="itemAction"
+                      href="//localhost:9876/q/status:open+-is:wip"
+                      tabindex="-1"
+                    >
+                      Open
+                    </a>
+                  </li>
+                  <li tabindex="-1">
+                    <span hidden="" tabindex="-1"> Merged </span>
+                    <a
+                      class="itemAction"
+                      href="//localhost:9876/q/status:merged"
+                      tabindex="-1"
+                    >
+                      Merged
+                    </a>
+                  </li>
+                  <li tabindex="-1">
+                    <span hidden="" tabindex="-1"> Abandoned </span>
+                    <a
+                      class="itemAction"
+                      href="//localhost:9876/q/status:abandoned"
+                      tabindex="-1"
+                    >
+                      Abandoned
+                    </a>
+                  </li>
+                </ul>
+              </li>
+              <li class="has-collapsible">
+                <a class="main" data-title="Documentation" href="">
+                  Documentation
+                  <gr-icon class="arrow-down" icon="arrow_drop_down"> </gr-icon>
+                </a>
+                <ul class="dropdown">
+                  <li tabindex="-1">
+                    <span hidden="" tabindex="-1"> Table of Contents </span>
+                    <a
+                      class="itemAction"
+                      href="https://gerrit-review.googlesource.com/Documentation/index.html"
+                      rel="noopener"
+                      tabindex="-1"
+                      target="_blank"
+                    >
+                      Table of Contents
+                    </a>
+                  </li>
+                  <li tabindex="-1">
+                    <span hidden="" tabindex="-1"> Searching </span>
+                    <a
+                      class="itemAction"
+                      href="https://gerrit-review.googlesource.com/Documentation/user-search.html"
+                      rel="noopener"
+                      tabindex="-1"
+                      target="_blank"
+                    >
+                      Searching
+                    </a>
+                  </li>
+                  <li tabindex="-1">
+                    <span hidden="" tabindex="-1"> Uploading </span>
+                    <a
+                      class="itemAction"
+                      href="https://gerrit-review.googlesource.com/Documentation/user-upload.html"
+                      rel="noopener"
+                      tabindex="-1"
+                      target="_blank"
+                    >
+                      Uploading
+                    </a>
+                  </li>
+                  <li tabindex="-1">
+                    <span hidden="" tabindex="-1"> Access Control </span>
+                    <a
+                      class="itemAction"
+                      href="https://gerrit-review.googlesource.com/Documentation/access-control.html"
+                      rel="noopener"
+                      tabindex="-1"
+                      target="_blank"
+                    >
+                      Access Control
+                    </a>
+                  </li>
+                  <li tabindex="-1">
+                    <span hidden="" tabindex="-1"> REST API </span>
+                    <a
+                      class="itemAction"
+                      href="https://gerrit-review.googlesource.com/Documentation/rest-api.html"
+                      rel="noopener"
+                      tabindex="-1"
+                      target="_blank"
+                    >
+                      REST API
+                    </a>
+                  </li>
+                  <li tabindex="-1">
+                    <span hidden="" tabindex="-1"> Project Owner Guide </span>
+                    <a
+                      class="itemAction"
+                      href="https://gerrit-review.googlesource.com/Documentation/intro-project-owner.html"
+                      rel="noopener"
+                      tabindex="-1"
+                      target="_blank"
+                    >
+                      Project Owner Guide
+                    </a>
+                  </li>
+                </ul>
+              </li>
+              <li class="has-collapsible">
+                <a class="main" data-title="Browse" href="">
+                  Browse
+                  <gr-icon class="arrow-down" icon="arrow_drop_down"> </gr-icon>
+                </a>
+                <ul class="dropdown"></ul>
+              </li>
+            </ul>
+          </div>
+          <div class="nav-header">
+            <a
+              aria-label="Open hamburger"
+              class="hamburger"
+              href=""
+              role="button"
+              title="Hamburger"
+            >
+              <gr-icon filled="" icon="menu"> </gr-icon>
+            </a>
+            <a class="bigTitle mobileTitle" href="//localhost:9876/">
+              <gr-endpoint-decorator name="header-mobile-title">
+                <div class="mobileTitleText"></div>
+              </gr-endpoint-decorator>
+            </a>
+            <div class="mobileRightItems">
+              <a
+                aria-label="Hide Searchbar"
+                class="searchButton"
+                role="button"
+                title="Search"
+              >
+                <gr-icon filled="" icon="search"> </gr-icon>
+              </a>
+              <gr-dropdown class="moreMenu" horizontal-align="center" link="">
+                <span class="linksTitle">
+                  <gr-icon filled="" icon="more_horiz"> </gr-icon>
+                </span>
+              </gr-dropdown>
+            </div>
+          </div>
+        </nav>
+        <div class="modelBackground"></div>
       `
     );
   });
diff --git a/polygerrit-ui/app/elements/settings/gr-email-editor/gr-email-editor.ts b/polygerrit-ui/app/elements/settings/gr-email-editor/gr-email-editor.ts
index 9c99ae0..2220d2f 100644
--- a/polygerrit-ui/app/elements/settings/gr-email-editor/gr-email-editor.ts
+++ b/polygerrit-ui/app/elements/settings/gr-email-editor/gr-email-editor.ts
@@ -3,20 +3,23 @@
  * Copyright 2016 Google LLC
  * SPDX-License-Identifier: Apache-2.0
  */
-import '@polymer/iron-input/iron-input';
 import '../../shared/gr-button/gr-button';
 import {EmailInfo} from '../../../types/common';
 import {getAppContext} from '../../../services/app-context';
 import {LitElement, css, html} from 'lit';
-import {customElement, property, state} from 'lit/decorators.js';
+import {customElement, state} from 'lit/decorators.js';
 import {sharedStyles} from '../../../styles/shared-styles';
 import {grFormStyles} from '../../../styles/gr-form-styles';
 import {ValueChangedEvent} from '../../../types/events';
 import {fire} from '../../../utils/event-util';
+import {deepClone} from '../../../utils/deep-util';
+import {userModelToken} from '../../../models/user/user-model';
+import {resolve} from '../../../models/dependency';
+import {subscribe} from '../../lit/subscription-controller';
 
 @customElement('gr-email-editor')
 export class GrEmailEditor extends LitElement {
-  @property({type: Boolean}) hasUnsavedChanges = false;
+  @state() private originalEmails: EmailInfo[] = [];
 
   /* private but used in test */
   @state() emails: EmailInfo[] = [];
@@ -29,6 +32,21 @@
 
   readonly restApiService = getAppContext().restApiService;
 
+  private readonly getUserModel = resolve(this, userModelToken);
+
+  constructor() {
+    super();
+    subscribe(
+      this,
+      () => this.getUserModel().emails$,
+      x => {
+        if (!x) return;
+        this.originalEmails = deepClone<EmailInfo[]>(x);
+        this.emails = deepClone<EmailInfo[]>(x);
+      }
+    );
+  }
+
   static override get styles() {
     return [
       sharedStyles,
@@ -82,24 +100,20 @@
     return html`<tr>
       <td class="emailColumn">${email.email}</td>
       <td class="preferredControl" @click=${this.handlePreferredControlClick}>
-        <iron-input
+        <!-- We have to use \`.checked\` rather then \`?checked\` as there
+              appears to be an issue when deleting, checked doesn't work correctly. -->
+        <input
           class="preferredRadio"
+          type="radio"
+          name="preferred"
+          .value=${email.email}
+          .checked=${email.preferred}
           @change=${this.handlePreferredChange}
-          .bindValue=${email.email}
-        >
-          <input
-            class="preferredRadio"
-            type="radio"
-            @change=${this.handlePreferredChange}
-            name="preferred"
-            ?checked=${email.preferred}
-          />
-        </iron-input>
+        />
       </td>
       <td>
         <gr-button
-          data-index=${index}
-          @click=${this.handleDeleteButton}
+          @click=${() => this.handleDeleteButton(index)}
           ?disabled=${this.checkPreferred(email.preferred)}
           class="remove-button"
           >Delete</gr-button
@@ -108,12 +122,6 @@
     </tr>`;
   }
 
-  loadData() {
-    return this.restApiService.getAccountEmails().then(emails => {
-      this.emails = emails ?? [];
-    });
-  }
-
   save() {
     const promises: Promise<unknown>[] = [];
 
@@ -127,24 +135,27 @@
       );
     }
 
-    return Promise.all(promises).then(() => {
+    return Promise.all(promises).then(async () => {
       this.emailsToRemove = [];
       this.newPreferred = '';
-      this.setHasUnsavedChanges(false);
+      await this.getUserModel().loadEmails(true);
+      this.setHasUnsavedChanges();
     });
   }
 
-  private handleDeleteButton(e: Event) {
-    const target = e.target;
-    if (!(target instanceof Element)) return;
-    const indexStr = target.getAttribute('data-index');
-    if (indexStr === null) return;
-    const index = Number(indexStr);
+  private handleDeleteButton(index: number) {
     const email = this.emails[index];
-    this.emailsToRemove = [...this.emailsToRemove, email];
+    // Don't add project to emailsToRemove if it wasn't in
+    // emails.
+    // We have to use JSON.stringify as we cloned the array
+    // so the reference is not the same.
+    const emails = this.emails.some(
+      x => JSON.stringify(email) === JSON.stringify(x)
+    );
+    if (emails) this.emailsToRemove.push(email);
     this.emails.splice(index, 1);
     this.requestUpdate();
-    this.setHasUnsavedChanges(true);
+    this.setHasUnsavedChanges();
   }
 
   private handlePreferredControlClick(e: Event) {
@@ -165,9 +176,10 @@
         this.emails[i].preferred = true;
         this.requestUpdate();
         this.newPreferred = preferred;
-        this.setHasUnsavedChanges(true);
+        this.setHasUnsavedChanges();
       } else if (this.emails[i].preferred) {
-        this.emails[i].preferred = false;
+        delete this.emails[i].preferred;
+        this.setHasUnsavedChanges();
         this.requestUpdate();
       }
     }
@@ -177,9 +189,11 @@
     return preferred ?? false;
   }
 
-  private setHasUnsavedChanges(value: boolean) {
-    this.hasUnsavedChanges = value;
-    fire(this, 'has-unsaved-changes-changed', {value});
+  private setHasUnsavedChanges() {
+    const hasUnsavedChanges =
+      JSON.stringify(this.originalEmails) !== JSON.stringify(this.emails) ||
+      this.emailsToRemove.length > 0;
+    fire(this, 'has-unsaved-changes-changed', {value: hasUnsavedChanges});
   }
 }
 
diff --git a/polygerrit-ui/app/elements/settings/gr-email-editor/gr-email-editor_test.ts b/polygerrit-ui/app/elements/settings/gr-email-editor/gr-email-editor_test.ts
index 25c9b97..84ed8dc 100644
--- a/polygerrit-ui/app/elements/settings/gr-email-editor/gr-email-editor_test.ts
+++ b/polygerrit-ui/app/elements/settings/gr-email-editor/gr-email-editor_test.ts
@@ -11,6 +11,7 @@
 
 suite('gr-email-editor tests', () => {
   let element: GrEmailEditor;
+  let accountEmailStub: sinon.SinonStub;
 
   setup(async () => {
     const emails = [
@@ -19,13 +20,14 @@
       {email: 'email@three.com'},
     ];
 
-    stubRestApi('getAccountEmails').returns(Promise.resolve(emails));
+    accountEmailStub = stubRestApi('getAccountEmails').returns(
+      Promise.resolve(emails)
+    );
 
     element = await fixture<GrEmailEditor>(
       html`<gr-email-editor></gr-email-editor>`
     );
 
-    await element.loadData();
     await element.updateComplete;
   });
 
@@ -45,20 +47,17 @@
             <tr>
               <td class="emailColumn">email@one.com</td>
               <td class="preferredControl">
-                <iron-input class="preferredRadio">
-                  <input
-                    class="preferredRadio"
-                    name="preferred"
-                    type="radio"
-                    value="email@one.com"
-                  />
-                </iron-input>
+                <input
+                  class="preferredRadio"
+                  name="preferred"
+                  type="radio"
+                  value="email@one.com"
+                />
               </td>
               <td>
                 <gr-button
                   aria-disabled="false"
                   class="remove-button"
-                  data-index="0"
                   role="button"
                   tabindex="0"
                 >
@@ -69,21 +68,17 @@
             <tr>
               <td class="emailColumn">email@two.com</td>
               <td class="preferredControl">
-                <iron-input class="preferredRadio">
-                  <input
-                    checked=""
-                    class="preferredRadio"
-                    name="preferred"
-                    type="radio"
-                    value="email@two.com"
-                  />
-                </iron-input>
+                <input
+                  class="preferredRadio"
+                  name="preferred"
+                  type="radio"
+                  value="email@two.com"
+                />
               </td>
               <td>
                 <gr-button
                   aria-disabled="true"
                   class="remove-button"
-                  data-index="1"
                   disabled=""
                   role="button"
                   tabindex="-1"
@@ -95,20 +90,17 @@
             <tr>
               <td class="emailColumn">email@three.com</td>
               <td class="preferredControl">
-                <iron-input class="preferredRadio">
-                  <input
-                    class="preferredRadio"
-                    name="preferred"
-                    type="radio"
-                    value="email@three.com"
-                  />
-                </iron-input>
+                <input
+                  class="preferredRadio"
+                  name="preferred"
+                  type="radio"
+                  value="email@three.com"
+                />
               </td>
               <td>
                 <gr-button
                   aria-disabled="false"
                   class="remove-button"
-                  data-index="2"
                   role="button"
                   tabindex="0"
                 >
@@ -123,6 +115,12 @@
   });
 
   test('renders', () => {
+    const hasUnsavedChangesSpy = sinon.spy();
+    element.addEventListener(
+      'has-unsaved-changes-changed',
+      hasUnsavedChangesSpy
+    );
+
     const rows = element
       .shadowRoot!.querySelector('table')!
       .querySelectorAll('tbody tr');
@@ -144,15 +142,21 @@
     );
     assert.isNotOk(rows[2].querySelector('gr-button')!.disabled);
 
-    assert.isFalse(element.hasUnsavedChanges);
+    assert.isFalse(hasUnsavedChangesSpy.called);
   });
 
   test('edit preferred', () => {
+    const hasUnsavedChangesSpy = sinon.spy();
+    element.addEventListener(
+      'has-unsaved-changes-changed',
+      hasUnsavedChangesSpy
+    );
+
     const radios = element
       .shadowRoot!.querySelector('table')!
       .querySelectorAll<HTMLInputElement>('input[type=radio]');
 
-    assert.isFalse(element.hasUnsavedChanges);
+    assert.isFalse(hasUnsavedChangesSpy.called);
     assert.isNotOk(element.newPreferred);
     assert.equal(element.emailsToRemove.length, 0);
     assert.equal(element.emails.length, 3);
@@ -162,7 +166,7 @@
 
     radios[0].click();
 
-    assert.isTrue(element.hasUnsavedChanges);
+    assert.isTrue(hasUnsavedChangesSpy.called);
     assert.isOk(element.newPreferred);
     assert.equal(element.emailsToRemove.length, 0);
     assert.equal(element.emails.length, 3);
@@ -172,18 +176,24 @@
   });
 
   test('delete email', () => {
+    const hasUnsavedChangesSpy = sinon.spy();
+    element.addEventListener(
+      'has-unsaved-changes-changed',
+      hasUnsavedChangesSpy
+    );
+
     const buttons = element
       .shadowRoot!.querySelector('table')!
       .querySelectorAll('gr-button');
 
-    assert.isFalse(element.hasUnsavedChanges);
+    assert.isFalse(hasUnsavedChangesSpy.called);
     assert.isNotOk(element.newPreferred);
     assert.equal(element.emailsToRemove.length, 0);
     assert.equal(element.emails.length, 3);
 
     buttons[2].click();
 
-    assert.isTrue(element.hasUnsavedChanges);
+    assert.isTrue(hasUnsavedChangesSpy.called);
     assert.isNotOk(element.newPreferred);
     assert.equal(element.emailsToRemove.length, 1);
     assert.equal(element.emails.length, 2);
@@ -192,6 +202,12 @@
   });
 
   test('save changes', async () => {
+    const hasUnsavedChangesSpy = sinon.spy();
+    element.addEventListener(
+      'has-unsaved-changes-changed',
+      hasUnsavedChangesSpy
+    );
+
     const deleteEmailSpy = spyRestApi('deleteAccountEmail');
     const setPreferredSpy = spyRestApi('setPreferredAccountEmail');
 
@@ -199,7 +215,7 @@
       .shadowRoot!.querySelector('table')!
       .querySelectorAll('tbody tr');
 
-    assert.isFalse(element.hasUnsavedChanges);
+    assert.isFalse(hasUnsavedChangesSpy.called);
     assert.isNotOk(element.newPreferred);
     assert.equal(element.emailsToRemove.length, 0);
     assert.equal(element.emails.length, 3);
@@ -208,16 +224,24 @@
     rows[0].querySelector('gr-button')!.click();
     rows[2].querySelector<HTMLInputElement>('input[type=radio]')!.click();
 
-    assert.isTrue(element.hasUnsavedChanges);
+    assert.isTrue(hasUnsavedChangesSpy.called);
+    assert.isTrue(hasUnsavedChangesSpy.lastCall.args[0].detail.value);
     assert.equal(element.newPreferred, 'email@three.com');
     assert.equal(element.emailsToRemove.length, 1);
     assert.equal(element.emailsToRemove[0].email, 'email@one.com');
     assert.equal(element.emails.length, 2);
 
+    accountEmailStub.restore();
+
+    accountEmailStub = stubRestApi('getAccountEmails').returns(
+      Promise.resolve(element.emails)
+    );
+
     await element.save();
     assert.equal(deleteEmailSpy.callCount, 1);
     assert.equal(deleteEmailSpy.getCall(0).args[0], 'email@one.com');
     assert.isTrue(setPreferredSpy.called);
     assert.equal(setPreferredSpy.getCall(0).args[0], 'email@three.com');
+    assert.isFalse(hasUnsavedChangesSpy.lastCall.args[0].detail.value);
   });
 });
diff --git a/polygerrit-ui/app/elements/settings/gr-preferences/gr-preferences.ts b/polygerrit-ui/app/elements/settings/gr-preferences/gr-preferences.ts
index bb0f1e9..fdb4f22 100644
--- a/polygerrit-ui/app/elements/settings/gr-preferences/gr-preferences.ts
+++ b/polygerrit-ui/app/elements/settings/gr-preferences/gr-preferences.ts
@@ -57,6 +57,9 @@
   @query('#allowSuggestCodeWhileCommenting')
   allowSuggestCodeWhileCommenting?: HTMLInputElement;
 
+  @query('#allowAiCommentAutocompletion')
+  allowAiCommentAutocompletion?: HTMLInputElement;
+
   @query('#defaultBaseForMergesSelect')
   defaultBaseForMergesSelect!: HTMLInputElement;
 
@@ -284,6 +287,7 @@
           </section>
           ${this.renderBrowserNotifications()}
           ${this.renderGenerateSuggestionWhenCommenting()}
+          ${this.renderAiCommentAutocompletion()}
           ${this.renderDefaultBaseForMerges()}
           <section>
             <label class="title" for="relativeDateInChangeTable"
@@ -519,6 +523,37 @@
     `;
   }
 
+  // When the experiment is over, move this back to render(),
+  // removing this function.
+  private renderAiCommentAutocompletion() {
+    if (
+      !this.flagsService.isEnabled(KnownExperimentId.COMMENT_AUTOCOMPLETION) ||
+      !this.suggestionsProvider
+    )
+      return nothing;
+    return html`
+      <section id="allowAiCommentAutocompletionSection">
+        <div class="title">
+          <label for="allowAiCommentAutocompletion"
+            >AI suggested text completions while commenting</label
+          >
+        </div>
+        <span class="value">
+          <input
+            id="allowAiCommentAutocompletion"
+            type="checkbox"
+            ?checked=${this.prefs?.allow_autocompleting_comments}
+            @change=${() => {
+              this.prefs!.allow_autocompleting_comments =
+                this.allowAiCommentAutocompletion!.checked;
+              this.requestUpdate();
+            }}
+          />
+        </span>
+      </section>
+    `;
+  }
+
   // When this is fixed and can be re-enabled, move this back to render()
   // and remove function.
   private renderDefaultBaseForMerges() {
diff --git a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-item.ts b/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-item.ts
deleted file mode 100644
index c7118f7..0000000
--- a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-item.ts
+++ /dev/null
@@ -1,40 +0,0 @@
-/**
- * @license
- * Copyright 2017 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-import {LitElement, css, html} from 'lit';
-import {customElement, property} from 'lit/decorators.js';
-import {grFormStyles} from '../../../styles/gr-form-styles';
-
-declare global {
-  interface HTMLElementTagNameMap {
-    'gr-settings-item': GrSettingsItem;
-  }
-}
-
-@customElement('gr-settings-item')
-export class GrSettingsItem extends LitElement {
-  @property({type: String})
-  anchor?: string;
-
-  @property({type: String})
-  override title = '';
-
-  static override get styles() {
-    return [
-      grFormStyles,
-      css`
-        :host {
-          display: block;
-          margin-bottom: var(--spacing-xxl);
-        }
-      `,
-    ];
-  }
-
-  override render() {
-    const anchor = this.anchor ?? '';
-    return html`<h2 id=${anchor} class="heading-2">${this.title}</h2>`;
-  }
-}
diff --git a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-menu-item.ts b/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-menu-item.ts
deleted file mode 100644
index 6c83bea..0000000
--- a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-menu-item.ts
+++ /dev/null
@@ -1,35 +0,0 @@
-/**
- * @license
- * Copyright 2017 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-import {pageNavStyles} from '../../../styles/gr-page-nav-styles';
-import {sharedStyles} from '../../../styles/shared-styles';
-import {LitElement, html} from 'lit';
-import {customElement, property} from 'lit/decorators.js';
-
-declare global {
-  interface HTMLElementTagNameMap {
-    'gr-settings-menu-item': GrSettingsMenuItem;
-  }
-}
-
-@customElement('gr-settings-menu-item')
-export class GrSettingsMenuItem extends LitElement {
-  @property({type: String})
-  href?: string;
-
-  @property({type: String})
-  override title = '';
-
-  static override get styles() {
-    return [sharedStyles, pageNavStyles];
-  }
-
-  override render() {
-    const href = this.href ?? '';
-    return html` <div class="navStyles">
-      <li><a href=${href}>${this.title}</a></li>
-    </div>`;
-  }
-}
diff --git a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view.ts b/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view.ts
index fd7d67b..7626e14 100644
--- a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view.ts
+++ b/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view.ts
@@ -38,7 +38,7 @@
 import {GrSshEditor} from '../gr-ssh-editor/gr-ssh-editor';
 import {GrGpgEditor} from '../gr-gpg-editor/gr-gpg-editor';
 import {GrEmailEditor} from '../gr-email-editor/gr-email-editor';
-import {fireAlert, fireTitleChange} from '../../../utils/event-util';
+import {fire, fireAlert, fireTitleChange} from '../../../utils/event-util';
 import {getAppContext} from '../../../services/app-context';
 import {BindValueChangeEvent, ValueChangedEvent} from '../../../types/events';
 import {LitElement, css, html} from 'lit';
@@ -190,7 +190,7 @@
     const message = await this.restApiService.confirmEmail(this.emailToken);
     if (message) fireAlert(this, message);
     this.getViewModel().clearToken();
-    await this.emailEditor.loadData();
+    await this.getUserModel().loadEmails(true);
   }
 
   override connectedCallback() {
@@ -230,8 +230,6 @@
       })
     );
 
-    promises.push(this.emailEditor.loadData());
-
     this._testOnly_loadingPromise = Promise.all(promises).then(() => {
       this.loading = false;
 
@@ -252,6 +250,7 @@
       css`
         :host {
           color: var(--primary-text-color);
+          overflow: auto;
         }
         h2 {
           font-family: var(--header-font-family);
@@ -340,6 +339,9 @@
               @unsaved-changes-changed=${(e: ValueChangedEvent<boolean>) => {
                 this.accountInfoChanged = e.detail.value;
               }}
+              @account-detail-update=${() => {
+                fire(this, 'account-detail-update', {});
+              }}
             ></gr-account-info>
             <gr-button
               @click=${() => {
@@ -437,7 +439,6 @@
           </h2>
           <fieldset id="watchedProjects">
             <gr-watched-projects-editor
-              ?hasUnsavedChanges=${this.watchedProjectsChanged}
               @has-unsaved-changes-changed=${(
                 e: ValueChangedEvent<boolean>
               ) => {
@@ -463,7 +464,6 @@
           <fieldset id="email">
             <gr-email-editor
               id="emailEditor"
-              ?hasUnsavedChanges=${this.emailsChanged}
               @has-unsaved-changes-changed=${(
                 e: ValueChangedEvent<boolean>
               ) => {
@@ -471,8 +471,8 @@
               }}
             ></gr-email-editor>
             <gr-button
-              @click=${() => {
-                this.emailEditor.save();
+              @click=${async () => {
+                await this.emailEditor.save();
               }}
               ?disabled=${!this.emailsChanged}
               >Save changes</gr-button
@@ -605,7 +605,7 @@
   };
 
   reloadAccountDetail() {
-    Promise.all([this.accountInfo.loadData(), this.emailEditor.loadData()]);
+    Promise.all([this.accountInfo.loadData()]);
   }
 
   // private but used in test
@@ -643,7 +643,7 @@
     if (!this.isNewEmailValid(this.newEmail)) return;
 
     this.addingEmail = true;
-    this.restApiService.addAccountEmail(this.newEmail).then(response => {
+    this.restApiService.addAccountEmail(this.newEmail).then(async response => {
       this.addingEmail = false;
 
       // If it was unsuccessful.
@@ -653,6 +653,8 @@
 
       this.lastSentVerificationEmail = this.newEmail;
       this.newEmail = '';
+
+      await this.getUserModel().loadEmails(true);
     });
   }
 
diff --git a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view_test.ts b/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view_test.ts
index b6690b6..74bcca9 100644
--- a/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view_test.ts
+++ b/polygerrit-ui/app/elements/settings/gr-settings-view/gr-settings-view_test.ts
@@ -331,12 +331,6 @@
     assert.isNotOk(element.lastSentVerificationEmail);
   });
 
-  test('emails are loaded without emailToken', () => {
-    const emailEditorLoadDataStub = sinon.stub(element.emailEditor, 'loadData');
-    element.firstUpdated();
-    assert.isTrue(emailEditorLoadDataStub.calledOnce);
-  });
-
   test('handleSaveChangeTable', () => {
     let newColumns = ['Owner', 'Project', 'Branch'];
     element.localChangeTableColumns = newColumns.slice(0);
@@ -387,10 +381,8 @@
       value: string | PromiseLike<string | null> | null
     ) => void;
     let confirmEmailStub: sinon.SinonStub;
-    let emailEditorLoadDataStub: sinon.SinonStub;
 
     setup(() => {
-      emailEditorLoadDataStub = sinon.stub(element.emailEditor, 'loadData');
       confirmEmailStub = stubRestApi('confirmEmail').returns(
         new Promise(resolve => {
           resolveConfirm = resolve;
@@ -406,16 +398,6 @@
       assert.isTrue(confirmEmailStub.calledWith('foo'));
     });
 
-    test('emails are not loaded initially', () => {
-      assert.isFalse(emailEditorLoadDataStub.called);
-    });
-
-    test('user emails are loaded after email confirmed', async () => {
-      resolveConfirm('bar');
-      await element._testOnly_loadingPromise;
-      assert.isTrue(emailEditorLoadDataStub.calledOnce);
-    });
-
     test('show-alert is fired when email is confirmed', async () => {
       const dispatchEventSpy = sinon.spy(element, 'dispatchEvent');
       resolveConfirm('bar');
diff --git a/polygerrit-ui/app/elements/settings/gr-watched-projects-editor/gr-watched-projects-editor.ts b/polygerrit-ui/app/elements/settings/gr-watched-projects-editor/gr-watched-projects-editor.ts
index f0f0f2f..583798c 100644
--- a/polygerrit-ui/app/elements/settings/gr-watched-projects-editor/gr-watched-projects-editor.ts
+++ b/polygerrit-ui/app/elements/settings/gr-watched-projects-editor/gr-watched-projects-editor.ts
@@ -6,7 +6,7 @@
 import '@polymer/iron-input/iron-input';
 import '../../shared/gr-autocomplete/gr-autocomplete';
 import '../../shared/gr-button/gr-button';
-import {customElement, property, query} from 'lit/decorators.js';
+import {customElement, query, state} from 'lit/decorators.js';
 import {
   AutocompleteQuery,
   GrAutocomplete,
@@ -22,6 +22,7 @@
 import {fire} from '../../../utils/event-util';
 import {PropertiesOfType} from '../../../utils/type-util';
 import {throwingErrorCallback} from '../../shared/gr-rest-api-interface/gr-rest-apis/gr-rest-api-helper';
+import {notDeepEqual} from '../../../utils/deep-util';
 
 type NotificationKey = PropertiesOfType<Required<ProjectWatchInfo>, boolean>;
 
@@ -43,13 +44,13 @@
   @query('#newProject')
   newProject?: GrAutocomplete;
 
-  @property({type: Boolean})
-  hasUnsavedChanges = false;
+  @state()
+  originalProjects?: ProjectWatchInfo[];
 
-  @property({type: Array})
+  @state()
   projects?: ProjectWatchInfo[];
 
-  @property({type: Array})
+  @state()
   projectsToRemove: ProjectWatchInfo[] = [];
 
   private readonly query: AutocompleteQuery = input =>
@@ -163,7 +164,8 @@
 
   loadData() {
     return this.restApiService.getWatchedProjects().then(projs => {
-      this.projects = projs;
+      this.originalProjects = projs;
+      this.projects = projs ? [...projs] : [];
     });
   }
 
@@ -186,9 +188,10 @@
         }
       })
       .then(projects => {
-        this.projects = projects;
+        this.originalProjects = projects;
+        this.projects = projects ? [...projects] : [];
         this.projectsToRemove = [];
-        this.setHasUnsavedChanges(false);
+        this.setHasUnsavedChanges();
       });
   }
 
@@ -206,13 +209,16 @@
   }
 
   private handleRemoveProject(project: ProjectWatchInfo) {
-    if (!this.projects) return;
+    if (!this.projects || !this.originalProjects) return;
     const index = this.projects.indexOf(project);
     if (index < 0) return;
     this.projects.splice(index, 1);
-    this.projectsToRemove.push(project);
+    // Don't add project to projectsToRemove if it wasn't in
+    // originalProjects.
+    if (this.originalProjects.includes(project))
+      this.projectsToRemove.push(project);
     this.requestUpdate();
-    this.setHasUnsavedChanges(true);
+    this.setHasUnsavedChanges();
   }
 
   // private but used in tests.
@@ -288,7 +294,7 @@
 
     this.newProject.clear();
     this.newFilter.value = '';
-    this.setHasUnsavedChanges(true);
+    this.setHasUnsavedChanges();
   }
 
   private handleCheckboxChange(
@@ -300,7 +306,7 @@
     const checked = el.checked;
     project[key] = !!checked;
     this.requestUpdate();
-    this.setHasUnsavedChanges(true);
+    this.setHasUnsavedChanges();
   }
 
   private handleNotifCellClick(e: Event) {
@@ -311,9 +317,11 @@
     }
   }
 
-  private setHasUnsavedChanges(value: boolean) {
-    this.hasUnsavedChanges = value;
-    fire(this, 'has-unsaved-changes-changed', {value});
+  private setHasUnsavedChanges() {
+    const hasUnsavedChanges =
+      notDeepEqual(this.originalProjects, this.projects) ||
+      this.projectsToRemove.length > 0;
+    fire(this, 'has-unsaved-changes-changed', {value: hasUnsavedChanges});
   }
 
   isFilterDefined(filter: string | null | undefined) {
diff --git a/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.ts b/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.ts
index d77bec9..704cecf 100644
--- a/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.ts
+++ b/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.ts
@@ -10,9 +10,13 @@
 import '../../plugins/gr-endpoint-param/gr-endpoint-param';
 import {getAppContext} from '../../../services/app-context';
 import {getDisplayName} from '../../../utils/display-name-util';
-import {isSelf, isServiceUser} from '../../../utils/account-util';
+import {
+  isDetailedAccount,
+  isSelf,
+  isServiceUser,
+} from '../../../utils/account-util';
 import {ChangeInfo, AccountInfo, ServerInfo} from '../../../types/common';
-import {assertIsDefined, hasOwnProperty} from '../../../utils/common-util';
+import {hasOwnProperty} from '../../../utils/common-util';
 import {fire} from '../../../utils/event-util';
 import {isInvolved} from '../../../utils/change-util';
 import {LitElement, css, html, TemplateResult} from 'lit';
@@ -21,7 +25,7 @@
 import {getRemovedByIconClickReason} from '../../../utils/attention-set-util';
 import {ifDefined} from 'lit/directives/if-defined.js';
 import {createSearchUrl} from '../../../models/views/search';
-import {accountsModelToken} from '../../../models/accounts-model/accounts-model';
+import {accountsModelToken} from '../../../models/accounts/accounts-model';
 import {resolve} from '../../../models/dependency';
 import {configModelToken} from '../../../models/config/config-model';
 import {userModelToken} from '../../../models/user/user-model';
@@ -198,15 +202,29 @@
     ];
   }
 
-  override async updated() {
-    assertIsDefined(this.account, 'account');
+  override updated() {
+    this.computeDetailedAccount();
+  }
+
+  private async computeDetailedAccount() {
+    if (!this.account) return;
+    // If this.account is already a detailed object, then there is no need to fill it.
+    if (isDetailedAccount(this.account)) return;
     const account = await this.getAccountsModel().fillDetails(this.account);
-    // AccountInfo returned by fillDetails has the email property set
-    // to the primary email of the account. This poses a problem in
-    // cases where a secondary email is used as the committer or author
-    // email. Therefore, only fill in the missing details to avoid
-    // displaying incorrect author or committer email.
-    if (account) this.account = Object.assign(account, this.account);
+    if (
+      account &&
+      // If we were not able to get a detailed object, then there is no point in updating the
+      // account.
+      isDetailedAccount(account) &&
+      account !== this.account &&
+      account._account_id === this.account._account_id
+    ) {
+      // AccountInfo returned by fillDetails has the email property set
+      // to the primary email of the account. This poses a problem in
+      // cases where a secondary email is used as the committer or author
+      // email. Therefore, only fill in the *missing* properties.
+      this.account = {...account, ...this.account};
+    }
   }
 
   override render() {
diff --git a/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar-stack.ts b/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar-stack.ts
index 863ee90..b445f75 100644
--- a/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar-stack.ts
+++ b/polygerrit-ui/app/elements/shared/gr-avatar/gr-avatar-stack.ts
@@ -17,7 +17,7 @@
 import {configModelToken} from '../../../models/config/config-model';
 import {subscribe} from '../../lit/subscription-controller';
 import {getDisplayName} from '../../../utils/display-name-util';
-import {accountsModelToken} from '../../../models/accounts-model/accounts-model';
+import {accountsModelToken} from '../../../models/accounts/accounts-model';
 import {isDefined} from '../../../types/types';
 import {when} from 'lit/directives/when.js';
 
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
index c27ca5b..68ab132 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
@@ -79,8 +79,12 @@
   commentModelToken,
 } from '../gr-comment-model/gr-comment-model';
 import {formStyles} from '../../../styles/form-styles';
-import {Interaction} from '../../../constants/reporting';
-import {Suggestion, SuggestionsProvider} from '../../../api/suggestions';
+import {Interaction, Timing} from '../../../constants/reporting';
+import {
+  AutocompleteCommentResponse,
+  Suggestion,
+  SuggestionsProvider,
+} from '../../../api/suggestions';
 import {when} from 'lit/directives/when.js';
 import {getDocUrl} from '../../../utils/url-util';
 import {configModelToken} from '../../../models/config/config-model';
@@ -89,6 +93,12 @@
 import {deepEqual} from '../../../utils/deep-util';
 import {GrSuggestionDiffPreview} from '../gr-suggestion-diff-preview/gr-suggestion-diff-preview';
 import {waitUntil} from '../../../utils/async-util';
+import {
+  AutocompleteCache,
+  AutocompletionContext,
+} from '../../../utils/autocomplete-cache';
+import {HintAppliedEventDetail, HintShownEventDetail} from '../../../api/embed';
+import {levenshteinDistance} from '../../../utils/string-util';
 
 // visible for testing
 export const AUTO_SAVE_DEBOUNCE_DELAY_MS = 2000;
@@ -224,7 +234,14 @@
    * An hint for autocompleting the comment message from plugin suggestion
    * providers.
    */
-  @state() autocompleteHint = '';
+  @state() autocompleteHint?: AutocompletionContext;
+
+  private autocompleteAcceptedHints: string[] = [];
+
+  /** Based on user preferences. */
+  @state() autocompleteEnabled = true;
+
+  readonly autocompleteCache = new AutocompleteCache();
 
   /* The 'dirty' state of !comment.unresolved, which will be saved on demand. */
   @state()
@@ -440,6 +457,7 @@
         this,
         () => this.getUserModel().preferences$,
         prefs => {
+          this.autocompleteEnabled = !!prefs.allow_autocompleting_comments;
           if (
             this.generateSuggestion !==
             !!prefs.allow_suggest_code_while_commenting
@@ -671,6 +689,10 @@
           /* Making up for the 2px reduced height above. */
           top: 1px;
         }
+        gr-suggestion-diff-preview,
+        gr-fix-suggestions {
+          margin-top: var(--spacing-s);
+        }
       `,
     ];
   }
@@ -893,12 +915,70 @@
         rows="4"
         .placeholder=${this.messagePlaceholder}
         text=${this.messageText}
-        autocompleteHint=${this.autocompleteHint}
+        autocompleteHint=${this.autocompleteHint?.commentCompletion ?? ''}
         @text-changed=${this.handleTextChanged}
+        @hintShown=${this.handleHintShown}
+        @hintApplied=${this.handleHintApplied}
       ></gr-suggestion-textarea>
     `;
   }
 
+  private handleHintShown(e: CustomEvent<HintShownEventDetail>) {
+    const context = this.autocompleteCache.get(e.detail.oldValue);
+    if (context?.commentCompletion !== e.detail.hint) return;
+
+    this.reportHintInteraction(
+      Interaction.COMMENT_COMPLETION_SUGGESTION_SHOWN,
+      context
+    );
+  }
+
+  private handleHintApplied(e: CustomEvent<HintAppliedEventDetail>) {
+    const context = this.autocompleteCache.get(e.detail.oldValue);
+    if (context?.commentCompletion !== e.detail.hint) return;
+
+    this.autocompleteAcceptedHints.push(e.detail.hint);
+    this.reportHintInteraction(
+      Interaction.COMMENT_COMPLETION_SUGGESTION_ACCEPTED,
+      context
+    );
+  }
+
+  private reportHintInteractionSaved() {
+    const content = this.messageText.trimEnd();
+    const acceptedHintsConcatenated = this.autocompleteAcceptedHints.join('');
+    const numExtraCharacters =
+      content.length - acceptedHintsConcatenated.length;
+    let distance = levenshteinDistance(acceptedHintsConcatenated, content);
+    if (numExtraCharacters > 0) {
+      distance -= numExtraCharacters;
+    }
+    const context = {
+      ...this.createAutocompletionBaseContext(),
+      similarCharacters: acceptedHintsConcatenated.length - distance,
+      maxSimilarCharacters: acceptedHintsConcatenated.length,
+      acceptedSuggestionsCount: this.autocompleteAcceptedHints.length,
+      totalAcceptedCharacters: acceptedHintsConcatenated.length,
+      savedDraftLength: content.length,
+    };
+    this.reportHintInteraction(
+      Interaction.COMMENT_COMPLETION_SAVE_DRAFT,
+      context
+    );
+  }
+
+  private reportHintInteraction(
+    interaction: Interaction,
+    context: Partial<AutocompletionContext>
+  ) {
+    context = {
+      ...context,
+      draftContent: '[REDACTED]',
+      commentCompletion: '[REDACTED]',
+    };
+    this.reporting.reportInteraction(interaction, context);
+  }
+
   private handleTextChanged(e: ValueChangedEvent) {
     const oldValue = this.messageText;
     const newValue = e.detail.value;
@@ -909,33 +989,20 @@
     // of the textare instead of needing a dedicated property.
     this.messageText = newValue;
 
-    this.handleTextChangedForAutocomplete(oldValue, newValue);
+    this.handleTextChangedForAutocomplete();
     this.autoSaveTrigger$.next();
     this.generateSuggestionTrigger$.next();
   }
 
   // visible for testing
-  handleTextChangedForAutocomplete(oldValue: string, newValue: string) {
-    if (oldValue === newValue) return;
-    // As soon as the user changes the text the hint for autocompletion
-    // is invalidated, *if* what the user typed does not match the
-    // autocompletion!
-    const charsAdded = newValue.length - oldValue.length;
-    if (
-      charsAdded > 0 &&
-      newValue.startsWith(oldValue) &&
-      this.autocompleteHint.startsWith(newValue.substring(oldValue.length))
-    ) {
-      // What the user typed matches the hint, so we keep the hint, but shorten
-      // it accordingly.
-      this.autocompleteHint = this.autocompleteHint.substring(charsAdded);
-      return;
+  handleTextChangedForAutocomplete() {
+    const cachedHint = this.autocompleteCache.get(this.messageText);
+    if (cachedHint) {
+      this.autocompleteHint = cachedHint;
+    } else {
+      this.autocompleteHint = undefined;
+      this.autocompleteTrigger$.next();
     }
-
-    // The default behavior is to reset the hint and to generate a new
-    // autocomplete suggestion.
-    this.autocompleteHint = '';
-    this.autocompleteTrigger$.next();
   }
 
   private renderCommentMessage() {
@@ -1349,6 +1416,7 @@
     const change = this.getChangeModel().getChange();
     if (
       !enabled ||
+      !this.autocompleteEnabled ||
       !suggestionsProvider?.autocompleteComment ||
       !change ||
       !this.comment?.patch_set ||
@@ -1358,6 +1426,7 @@
       return;
     }
     const commentText = this.messageText;
+    this.reporting.time(Timing.COMMENT_COMPLETION);
     const response = await suggestionsProvider.autocompleteComment({
       id: id(this.comment),
       commentText,
@@ -1367,11 +1436,51 @@
       range: this.comment.range,
       lineNumber: this.comment.line,
     });
-    // If between request and response the user has changed the message, then
-    // ignore the suggestion for the old message text.
-    if (this.messageText !== commentText) return;
+    const elapsed = this.reporting.timeEnd(Timing.COMMENT_COMPLETION);
+    const context = this.createAutocompletionContext(
+      commentText,
+      response,
+      elapsed
+    );
+    this.reportHintInteraction(
+      Interaction.COMMENT_COMPLETION_SUGGESTION_FETCHED,
+      context
+    );
     if (!response?.completion) return;
-    this.autocompleteHint = response.completion;
+    // Note that we are setting the cache value for `commentText` and getting the value
+    // for `this.messageText`.
+    this.autocompleteCache.set(context);
+    this.autocompleteHint = this.autocompleteCache.get(this.messageText);
+  }
+
+  private createAutocompletionBaseContext(): Partial<AutocompletionContext> {
+    return {
+      commentId: id(this.comment!),
+      commentNumber: this.comments?.length ?? 0,
+      filePath: this.comment!.path,
+      fileExtension: getFileExtension(this.comment!.path ?? ''),
+    };
+  }
+
+  private createAutocompletionContext(
+    draftContent: string,
+    response: AutocompleteCommentResponse,
+    requestDurationMs: number
+  ): AutocompletionContext {
+    const commentCompletion = response.completion ?? '';
+    return {
+      ...this.createAutocompletionBaseContext(),
+
+      draftContent,
+      draftContentLength: draftContent.length,
+      commentCompletion,
+      commentCompletionLength: commentCompletion.length,
+
+      isFullCommentPrediction: draftContent.length === 0,
+      draftInSyncWithSuggestionLength: 0,
+      modelVersion: response.modelVersion ?? '',
+      requestDurationMs,
+    };
   }
 
   private renderRobotActions() {
@@ -1800,6 +1909,7 @@
     if (this.isFixSuggestionChanged()) {
       draft.fix_suggestions = this.getFixSuggestions();
     }
+    this.reportHintInteractionSaved();
     return this.getCommentsModel().saveDraft(draft, options.showToast);
   }
 
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_test.ts b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_test.ts
index 7b4f63a..444a43f 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_test.ts
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment_test.ts
@@ -898,27 +898,39 @@
 
   suite('handleTextChangedForAutocomplete', () => {
     test('foo -> foo with asdf', async () => {
-      element.autocompleteHint = 'asdf';
-      element.handleTextChangedForAutocomplete('foo', 'foo');
-      assert.equal(element.autocompleteHint, 'asdf');
+      const ctx = {draftContent: 'foo', commentCompletion: 'asdf'};
+      element.autocompleteHint = ctx;
+      element.autocompleteCache.set(ctx);
+      element.messageText = 'foo';
+      element.handleTextChangedForAutocomplete();
+      assert.equal(element.autocompleteHint.commentCompletion, 'asdf');
     });
 
     test('foo -> bar with asdf', async () => {
-      element.autocompleteHint = 'asdf';
-      element.handleTextChangedForAutocomplete('foo', 'bar');
-      assert.equal(element.autocompleteHint, '');
+      const ctx = {draftContent: 'foo', commentCompletion: 'asdf'};
+      element.autocompleteHint = ctx;
+      element.autocompleteCache.set(ctx);
+      element.messageText = 'bar';
+      element.handleTextChangedForAutocomplete();
+      assert.isUndefined(element.autocompleteHint);
     });
 
     test('foo -> foofoo with asdf', async () => {
-      element.autocompleteHint = 'asdf';
-      element.handleTextChangedForAutocomplete('foo', 'foofoo');
-      assert.equal(element.autocompleteHint, '');
+      const ctx = {draftContent: 'foo', commentCompletion: 'asdf'};
+      element.autocompleteHint = ctx;
+      element.autocompleteCache.set(ctx);
+      element.messageText = 'foofoo';
+      element.handleTextChangedForAutocomplete();
+      assert.isUndefined(element.autocompleteHint);
     });
 
     test('foo -> foofoo with foomore', async () => {
-      element.autocompleteHint = 'foomore';
-      element.handleTextChangedForAutocomplete('foo', 'foofoo');
-      assert.equal(element.autocompleteHint, 'more');
+      const ctx = {draftContent: 'foo', commentCompletion: 'foomore'};
+      element.autocompleteHint = ctx;
+      element.autocompleteCache.set(ctx);
+      element.messageText = 'foofoo';
+      element.handleTextChangedForAutocomplete();
+      assert.equal(element.autocompleteHint.commentCompletion, 'more');
     });
   });
 
diff --git a/polygerrit-ui/app/elements/shared/gr-fix-suggestions/gr-fix-suggestions.ts b/polygerrit-ui/app/elements/shared/gr-fix-suggestions/gr-fix-suggestions.ts
index 63c3832..195eeb6 100644
--- a/polygerrit-ui/app/elements/shared/gr-fix-suggestions/gr-fix-suggestions.ts
+++ b/polygerrit-ui/app/elements/shared/gr-fix-suggestions/gr-fix-suggestions.ts
@@ -87,6 +87,9 @@
   static override get styles() {
     return [
       css`
+        :host {
+          display: block;
+        }
         .header {
           background-color: var(--background-color-primary);
           border: 1px solid var(--border-color);
diff --git a/polygerrit-ui/app/elements/shared/gr-suggestion-diff-preview/gr-suggestion-diff-preview.ts b/polygerrit-ui/app/elements/shared/gr-suggestion-diff-preview/gr-suggestion-diff-preview.ts
index c533a5e..e1d4f89 100644
--- a/polygerrit-ui/app/elements/shared/gr-suggestion-diff-preview/gr-suggestion-diff-preview.ts
+++ b/polygerrit-ui/app/elements/shared/gr-suggestion-diff-preview/gr-suggestion-diff-preview.ts
@@ -152,9 +152,16 @@
   static override get styles() {
     return [
       css`
+        :host {
+          display: block;
+        }
         .buttons {
           text-align: right;
         }
+        .diff-container {
+          border: 1px solid var(--border-color);
+          border-top: none;
+        }
         code {
           max-width: var(--gr-formatted-text-prose-max-width, none);
           background-color: var(--background-color-secondary);
@@ -221,14 +228,16 @@
     if (!anyLineTooLong(diff)) {
       this.syntaxLayer.process(diff);
     }
-    return html`<gr-diff
-      .prefs=${this.overridePartialDiffPrefs()}
-      .path=${this.preview.filepath}
-      .diff=${diff}
-      .layers=${this.layers}
-      .renderPrefs=${this.renderPrefs}
-      .viewMode=${DiffViewMode.UNIFIED}
-    ></gr-diff>`;
+    return html`<div class="diff-container">
+      <gr-diff
+        .prefs=${this.overridePartialDiffPrefs()}
+        .path=${this.preview.filepath}
+        .diff=${diff}
+        .layers=${this.layers}
+        .renderPrefs=${this.renderPrefs}
+        .viewMode=${DiffViewMode.UNIFIED}
+      ></gr-diff>
+    </div>`;
   }
 
   private async fetchFixPreview() {
diff --git a/polygerrit-ui/app/elements/shared/gr-suggestion-diff-preview/gr-suggestion-diff-preview_test.ts b/polygerrit-ui/app/elements/shared/gr-suggestion-diff-preview/gr-suggestion-diff-preview_test.ts
index 86be868..2630aad 100644
--- a/polygerrit-ui/app/elements/shared/gr-suggestion-diff-preview/gr-suggestion-diff-preview_test.ts
+++ b/polygerrit-ui/app/elements/shared/gr-suggestion-diff-preview/gr-suggestion-diff-preview_test.ts
@@ -103,10 +103,12 @@
     assert.shadowDom.equal(
       element,
       /* HTML */ `
-        <gr-diff
-          class="disable-context-control-buttons hide-line-length-indicator"
-        >
-        </gr-diff>
+        <div class="diff-container">
+          <gr-diff
+            class="disable-context-control-buttons hide-line-length-indicator"
+          >
+          </gr-diff>
+        </div>
       `,
       {ignoreAttributes: ['style']}
     );
diff --git a/polygerrit-ui/app/elements/shared/gr-suggestion-textarea/gr-suggestion-textarea.ts b/polygerrit-ui/app/elements/shared/gr-suggestion-textarea/gr-suggestion-textarea.ts
index 2d22f6a..a8a779d 100644
--- a/polygerrit-ui/app/elements/shared/gr-suggestion-textarea/gr-suggestion-textarea.ts
+++ b/polygerrit-ui/app/elements/shared/gr-suggestion-textarea/gr-suggestion-textarea.ts
@@ -348,6 +348,12 @@
           position: relative;
           --gr-textarea-padding: var(--spacing-s);
           --gr-textarea-border-width: 0px;
+          --gr-textarea-border-color: var(--border-color);
+          --input-field-bg: var(--view-background-color);
+          --input-field-disabled-bg: var(--view-background-color);
+          --secondary-bg-color: var(--background-color-secondary);
+          --text-default: var(--primary-text-color);
+          --text-disabled: var(--deemphasized-text-color);
           --text-secondary: var(--deemphasized-text-color);
           --iron-autogrow-textarea_-_padding: var(--spacing-s);
         }
diff --git a/polygerrit-ui/app/embed/diff/gr-syntax-layer/gr-syntax-layer-worker.ts b/polygerrit-ui/app/embed/diff/gr-syntax-layer/gr-syntax-layer-worker.ts
index 5074290..9337951 100644
--- a/polygerrit-ui/app/embed/diff/gr-syntax-layer/gr-syntax-layer-worker.ts
+++ b/polygerrit-ui/app/embed/diff/gr-syntax-layer/gr-syntax-layer-worker.ts
@@ -23,6 +23,7 @@
   ['application/typescript', 'typescript'],
   ['application/xml', 'xml'],
   ['application/xquery', 'xquery'],
+  ['application/x-epp', 'epp'],
   ['application/x-erb', 'erb'],
   ['text/css', 'css'],
   ['text/html', 'html'],
diff --git a/polygerrit-ui/app/embed/gr-textarea.ts b/polygerrit-ui/app/embed/gr-textarea.ts
index 628b65b..9b88e9c 100644
--- a/polygerrit-ui/app/embed/gr-textarea.ts
+++ b/polygerrit-ui/app/embed/gr-textarea.ts
@@ -456,13 +456,7 @@
     const value = await this.getValue();
     this.innerValue = value;
 
-    this.dispatchEvent(
-      new CustomEvent('input', {
-        detail: {
-          value: this.value,
-        },
-      })
-    );
+    this.fire('input', {value: this.value});
   }
 
   private onFocus(event: Event) {
@@ -492,7 +486,7 @@
       (event.ctrlKey || event.metaKey)
     ) {
       event.preventDefault();
-      this.dispatchEvent(new CustomEvent('saveShortcut'));
+      this.fire('saveShortcut');
     }
     await this.toggleHintVisibilityIfAny();
   }
@@ -507,7 +501,13 @@
   }
 
   private handleScroll() {
-    this.dispatchEvent(new CustomEvent('scroll'));
+    this.fire('scroll');
+  }
+
+  private fire<T>(type: string, detail?: T) {
+    this.dispatchEvent(
+      new CustomEvent(type, {detail, bubbles: true, composed: true})
+    );
   }
 
   private async handleTabKeyPress(event: KeyboardEvent) {
@@ -529,14 +529,7 @@
     await this.putCursorAtEnd();
     await this.onInput(event);
 
-    this.dispatchEvent(
-      new CustomEvent('hintApplied', {
-        detail: {
-          hint,
-          oldValue,
-        },
-      })
-    );
+    this.fire('hintApplied', {hint, oldValue});
   }
 
   private async toggleHintVisibilityIfAny() {
@@ -572,6 +565,7 @@
   }
 
   private addHintSpanAtEndOfContent(editableDivElement: Node, hint: string) {
+    const oldValue = this.value ?? '';
     const hintSpan = document.createElement('span');
     hintSpan.classList.add(AUTOCOMPLETE_HINT_CLASS);
     hintSpan.setAttribute('role', 'alert');
@@ -581,26 +575,16 @@
     );
     hintSpan.dataset['hint'] = hint;
     editableDivElement.appendChild(hintSpan);
-    this.dispatchEvent(
-      new CustomEvent('hintShown', {
-        detail: {
-          hint,
-        },
-      })
-    );
+    this.fire('hintShown', {hint, oldValue});
   }
 
   private removeHintSpanIfShown() {
     const hintSpan = this.hintSpan();
     if (hintSpan) {
       hintSpan.remove();
-      this.dispatchEvent(
-        new CustomEvent('hintDismissed', {
-          detail: {
-            hint: (hintSpan as HTMLElement).dataset['hint'],
-          },
-        })
-      );
+      this.fire('hintDismissed', {
+        hint: (hintSpan as HTMLElement).dataset['hint'],
+      });
     }
   }
 
@@ -616,13 +600,7 @@
     event?.preventDefault();
     event?.stopImmediatePropagation();
 
-    this.dispatchEvent(
-      new CustomEvent('cursorPositionChange', {
-        detail: {
-          position: this.getCursorPosition(),
-        },
-      })
-    );
+    this.fire('cursorPositionChange', {position: this.getCursorPosition()});
   }
 
   private async updateValueInDom() {
diff --git a/polygerrit-ui/app/models/accounts-model/accounts-model_test.ts b/polygerrit-ui/app/models/accounts-model/accounts-model_test.ts
deleted file mode 100644
index 53c90a6..0000000
--- a/polygerrit-ui/app/models/accounts-model/accounts-model_test.ts
+++ /dev/null
@@ -1,42 +0,0 @@
-/**
- * @license
- * Copyright 2022 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-import '../../test/common-test-setup';
-import {EmailAddress} from '../../api/rest-api';
-import {getAppContext} from '../../services/app-context';
-import {stubRestApi} from '../../test/test-utils';
-import {AccountsModel} from './accounts-model';
-import {assert} from '@open-wc/testing';
-
-suite('accounts-model tests', () => {
-  let model: AccountsModel;
-
-  setup(() => {
-    model = new AccountsModel(getAppContext().restApiService);
-  });
-
-  teardown(() => {
-    model.finalize();
-  });
-
-  test('invalid account makes only one request', () => {
-    const response = {...new Response(), status: 404};
-    const getAccountDetails = stubRestApi('getAccountDetails').callsFake(
-      (_, errFn) => {
-        if (errFn !== undefined) {
-          errFn(response);
-        }
-        return Promise.resolve(undefined);
-      }
-    );
-
-    model.fillDetails({email: 'Invalid_email@def.com' as EmailAddress});
-    assert.equal(getAccountDetails.callCount, 1);
-
-    model.fillDetails({email: 'Invalid_email@def.com' as EmailAddress});
-    assert.equal(getAccountDetails.callCount, 1);
-  });
-});
diff --git a/polygerrit-ui/app/models/accounts-model/accounts-model.ts b/polygerrit-ui/app/models/accounts/accounts-model.ts
similarity index 95%
rename from polygerrit-ui/app/models/accounts-model/accounts-model.ts
rename to polygerrit-ui/app/models/accounts/accounts-model.ts
index 0802f06..6eedcbe8 100644
--- a/polygerrit-ui/app/models/accounts-model/accounts-model.ts
+++ b/polygerrit-ui/app/models/accounts/accounts-model.ts
@@ -42,7 +42,7 @@
   ): Promise<AccountDetailInfo | AccountInfo> {
     const current = this.getState();
     const id = getUserId(partialAccount);
-    if (hasOwnProperty(current.accounts, id)) return current.accounts[id];
+    if (hasOwnProperty(current.accounts, id)) return {...current.accounts[id]};
     // It is possible to add emails to CC when they don't have a Gerrit
     // account. In this case getAccountDetails will return a 404 error then
     // we at least use what is in partialAccount.
diff --git a/polygerrit-ui/app/models/accounts/accounts-model_test.ts b/polygerrit-ui/app/models/accounts/accounts-model_test.ts
new file mode 100644
index 0000000..e84723c
--- /dev/null
+++ b/polygerrit-ui/app/models/accounts/accounts-model_test.ts
@@ -0,0 +1,71 @@
+/**
+ * @license
+ * Copyright 2022 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import '../../test/common-test-setup';
+import {
+  AccountDetailInfo,
+  AccountId,
+  EmailAddress,
+  Timestamp,
+} from '../../api/rest-api';
+import {getAppContext} from '../../services/app-context';
+import {stubRestApi} from '../../test/test-utils';
+import {AccountsModel} from './accounts-model';
+import {assert} from '@open-wc/testing';
+
+const KERMIT: AccountDetailInfo = {
+  _account_id: 1 as AccountId,
+  name: 'Kermit',
+  registered_on: '2015-03-12 18:32:08.000000000' as Timestamp,
+};
+
+suite('accounts-model tests', () => {
+  let model: AccountsModel;
+
+  setup(() => {
+    model = new AccountsModel(getAppContext().restApiService);
+  });
+
+  teardown(() => {
+    model.finalize();
+  });
+
+  test('basic lookup', async () => {
+    const stub = stubRestApi('getAccountDetails').returns(
+      Promise.resolve(KERMIT)
+    );
+
+    let filled = await model.fillDetails({_account_id: 1 as AccountId});
+    assert.equal(filled.name, 'Kermit');
+    assert.equal(filled, KERMIT);
+    assert.equal(stub.callCount, 1);
+
+    filled = await model.fillDetails({_account_id: 1 as AccountId});
+    assert.equal(filled.name, 'Kermit');
+    // Cache objects are cloned on lookup, so this is a different object.
+    assert.notEqual(filled, KERMIT);
+    // Did not have to call the REST API again.
+    assert.equal(stub.callCount, 1);
+  });
+
+  test('invalid account makes only one request', () => {
+    const response = {...new Response(), status: 404};
+    const getAccountDetails = stubRestApi('getAccountDetails').callsFake(
+      (_, errFn) => {
+        if (errFn !== undefined) {
+          errFn(response);
+        }
+        return Promise.resolve(undefined);
+      }
+    );
+
+    model.fillDetails({email: 'Invalid_email@def.com' as EmailAddress});
+    assert.equal(getAccountDetails.callCount, 1);
+
+    model.fillDetails({email: 'Invalid_email@def.com' as EmailAddress});
+    assert.equal(getAccountDetails.callCount, 1);
+  });
+});
diff --git a/polygerrit-ui/app/models/comments/comments-model.ts b/polygerrit-ui/app/models/comments/comments-model.ts
index f9a8401..497962f 100644
--- a/polygerrit-ui/app/models/comments/comments-model.ts
+++ b/polygerrit-ui/app/models/comments/comments-model.ts
@@ -56,7 +56,7 @@
 import {Deduping} from '../../api/reporting';
 import {extractMentionedUsers, getUserId} from '../../utils/account-util';
 import {SpecialFilePath} from '../../constants/constants';
-import {AccountsModel} from '../accounts-model/accounts-model';
+import {AccountsModel} from '../accounts/accounts-model';
 import {
   distinctUntilChanged,
   map,
@@ -432,7 +432,7 @@
     threads.filter(t => !isNewThread(t) && isDraftThread(t))
   );
 
-  public readonly threadsWithSuggestions$ = select(
+  public readonly threadsWithUnappliedSuggestions$ = select(
     combineLatest([this.threads$, this.changeModel.latestPatchNum$]),
     ([threads, latestPs]) =>
       threads.filter(
diff --git a/polygerrit-ui/app/models/comments/comments-model_test.ts b/polygerrit-ui/app/models/comments/comments-model_test.ts
index 0d3df42..b3dbc08 100644
--- a/polygerrit-ui/app/models/comments/comments-model_test.ts
+++ b/polygerrit-ui/app/models/comments/comments-model_test.ts
@@ -28,7 +28,7 @@
 import {changeModelToken} from '../change/change-model';
 import {assert} from '@open-wc/testing';
 import {testResolver} from '../../test/common-test-setup';
-import {accountsModelToken} from '../accounts-model/accounts-model';
+import {accountsModelToken} from '../accounts/accounts-model';
 import {ChangeComments} from '../../elements/diff/gr-comment-api/gr-comment-api';
 import {changeViewModelToken} from '../views/change';
 import {navigationToken} from '../../elements/core/gr-navigation/gr-navigation';
diff --git a/polygerrit-ui/app/models/user/user-model.ts b/polygerrit-ui/app/models/user/user-model.ts
index cd6a66a..4973307 100644
--- a/polygerrit-ui/app/models/user/user-model.ts
+++ b/polygerrit-ui/app/models/user/user-model.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 import {from, of, Observable} from 'rxjs';
-import {filter, switchMap} from 'rxjs/operators';
+import {filter, switchMap, tap} from 'rxjs/operators';
 import {
   DiffPreferencesInfo as DiffPreferencesInfoAPI,
   DiffViewMode,
@@ -13,6 +13,7 @@
   AccountCapabilityInfo,
   AccountDetailInfo,
   EditPreferencesInfo,
+  EmailInfo,
   PreferencesInfo,
   TopMenuItemInfo,
 } from '../../types/common';
@@ -48,6 +49,7 @@
    * `account` is known, then use `accountLoaded` below.
    */
   account?: AccountDetailInfo;
+  emails?: EmailInfo[];
   /**
    * Starts as `false` and switches to `true` after the first `getAccount` call.
    * A common use case for this is to wait with loading or doing something until
@@ -82,6 +84,15 @@
     userState => userState.account
   );
 
+  readonly emails$: Observable<EmailInfo[] | undefined> = select(
+    this.state$,
+    userState => userState.emails
+  ).pipe(
+    tap(emails => {
+      if (emails === undefined) this.loadEmails();
+    })
+  );
+
   /**
    * Only emits once we have tried to actually load the account. Note that
    * this does not initially emit a value.
@@ -148,12 +159,8 @@
     super({
       accountLoaded: false,
     });
+    this.loadAccount();
     this.subscriptions = [
-      from(this.restApiService.getAccount()).subscribe(
-        (account?: AccountDetailInfo) => {
-          this.setAccount(account);
-        }
-      ),
       this.loadedAccount$
         .pipe(
           switchMap(account => {
@@ -261,4 +268,22 @@
   setAccount(account?: AccountDetailInfo) {
     this.updateState({account, accountLoaded: true});
   }
+
+  private setAccountEmails(emails?: EmailInfo[]) {
+    this.updateState({emails});
+  }
+
+  loadAccount(noCache?: boolean) {
+    if (noCache) this.restApiService.invalidateAccountsDetailCache();
+    return this.restApiService.getAccount().then(account => {
+      this.setAccount(account);
+    });
+  }
+
+  loadEmails(noCache?: boolean) {
+    if (noCache) this.restApiService.invalidateAccountsEmailCache();
+    return this.restApiService.getAccountEmails().then(emails => {
+      this.setAccountEmails(emails);
+    });
+  }
 }
diff --git a/polygerrit-ui/app/node_modules_licenses/licenses.ts b/polygerrit-ui/app/node_modules_licenses/licenses.ts
index 9fa2e89..21fab53 100644
--- a/polygerrit-ui/app/node_modules_licenses/licenses.ts
+++ b/polygerrit-ui/app/node_modules_licenses/licenses.ts
@@ -454,6 +454,14 @@
     },
   },
   {
+    name: 'highlightjs-epp',
+    license: {
+      name: 'highlightjs-epp',
+      type: LicenseTypes.Bsd3,
+      packageLicenseFile: 'LICENSE',
+    },
+  },
+  {
     name: 'highlightjs-structured-text',
     license: {
       name: 'highlightjs-structured-text',
diff --git a/polygerrit-ui/app/package.json b/polygerrit-ui/app/package.json
index 73816d2..dea0e8b 100644
--- a/polygerrit-ui/app/package.json
+++ b/polygerrit-ui/app/package.json
@@ -35,8 +35,9 @@
     "@webcomponents/shadycss": "^1.11.2",
     "@webcomponents/webcomponentsjs": "^1.3.3",
     "highlight.js": "^11.9.0",
-    "highlightjs-closure-templates": "https://github.com/highlightjs/highlightjs-closure-templates",
-    "highlightjs-structured-text": "https://github.com/highlightjs/highlightjs-structured-text",
+    "highlightjs-closure-templates": "https://github.com/highlightjs/highlightjs-closure-templates#02fb0646e0499084f96a99b8c6f4a0d7bd1d33ba",
+    "highlightjs-epp": "https://github.com/highlightjs/highlightjs-epp#9f9e1a92f37c217c68899c7d3bdccb4d134681b9",
+    "highlightjs-structured-text": "https://github.com/highlightjs/highlightjs-structured-text#e68dd7aa829529fb6c40d6287585f43273605a9e",
     "immer": "^9.0.21",
     "lit": "^3.1.2",
     "polymer-bridges": "file:../../polymer-bridges",
diff --git a/polygerrit-ui/app/services/app-context-init.ts b/polygerrit-ui/app/services/app-context-init.ts
index 40517ac..8536492 100644
--- a/polygerrit-ui/app/services/app-context-init.ts
+++ b/polygerrit-ui/app/services/app-context-init.ts
@@ -34,7 +34,7 @@
 import {
   AccountsModel,
   accountsModelToken,
-} from '../models/accounts-model/accounts-model';
+} from '../models/accounts/accounts-model';
 import {
   DashboardViewModel,
   dashboardViewModelToken,
diff --git a/polygerrit-ui/app/services/gr-reporting/gr-reporting.ts b/polygerrit-ui/app/services/gr-reporting/gr-reporting.ts
index 6df2c67..e175228 100644
--- a/polygerrit-ui/app/services/gr-reporting/gr-reporting.ts
+++ b/polygerrit-ui/app/services/gr-reporting/gr-reporting.ts
@@ -55,7 +55,7 @@
   /**
    * Finish named timer and report it to server.
    */
-  timeEnd(name: Timing, eventDetails?: EventDetails): void;
+  timeEnd(name: Timing, eventDetails?: EventDetails): number;
   /**
    * Get a timer object for reporting a user timing. The start time will be
    * the time that the object has been created, and the end time will be the
diff --git a/polygerrit-ui/app/services/gr-reporting/gr-reporting_impl.ts b/polygerrit-ui/app/services/gr-reporting/gr-reporting_impl.ts
index 1eb3bc2..781f370 100644
--- a/polygerrit-ui/app/services/gr-reporting/gr-reporting_impl.ts
+++ b/polygerrit-ui/app/services/gr-reporting/gr-reporting_impl.ts
@@ -770,23 +770,26 @@
   /**
    * Finish named timer and report it to server.
    */
-  timeEnd(name: Timing, eventDetails?: EventDetails) {
+  timeEnd(name: Timing, eventDetails?: EventDetails): number {
     if (!hasOwnProperty(this._baselines, name)) {
-      return;
+      return 0;
     }
-    const baseTime = this._baselines[name];
+    const begin = this._baselines[name];
     delete this._baselines[name];
-    this._reportTiming(name, now() - baseTime, eventDetails);
+    const end = now();
+    const elapsed = end - begin;
+    this._reportTiming(name, elapsed, eventDetails);
 
     // Finalize the interval. Either from a registered start mark or
     // the navigation start time (if baseTime is 0).
-    if (baseTime !== 0) {
+    if (begin !== 0) {
       window.performance.measure(name, `${name}-start`);
     } else {
       // Microsoft Edge does not handle the 2nd param correctly
       // (if undefined).
       window.performance.measure(name);
     }
+    return elapsed;
   }
 
   /**
diff --git a/polygerrit-ui/app/services/gr-reporting/gr-reporting_mock.ts b/polygerrit-ui/app/services/gr-reporting/gr-reporting_mock.ts
index fb1f0c3..7cb777a 100644
--- a/polygerrit-ui/app/services/gr-reporting/gr-reporting_mock.ts
+++ b/polygerrit-ui/app/services/gr-reporting/gr-reporting_mock.ts
@@ -71,5 +71,5 @@
   setRepoName: () => {},
   setChangeId: () => {},
   time: () => {},
-  timeEnd: () => {},
+  timeEnd: () => 0,
 };
diff --git a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api-impl.ts b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api-impl.ts
index 0be3ab5..7a12e7a 100644
--- a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api-impl.ts
+++ b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api-impl.ts
@@ -1565,6 +1565,10 @@
     this._restApiHelper.invalidateFetchPromisesPrefix('/accounts/self/detail');
   }
 
+  invalidateAccountsEmailCache() {
+    this._restApiHelper.invalidateFetchPromisesPrefix('/accounts/self/emails');
+  }
+
   getGroups(filter: string, groupsPerPage: number, offset?: number) {
     const url = this._getGroupsUrl(filter, groupsPerPage, offset);
 
diff --git a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts
index 947952c..814e97a 100644
--- a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts
+++ b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts
@@ -542,6 +542,7 @@
   invalidateReposCache(): void;
   invalidateAccountsCache(): void;
   invalidateAccountsDetailCache(): void;
+  invalidateAccountsEmailCache(): void;
   removeFromAttentionSet(
     changeNum: NumericChangeId,
     user: AccountId,
diff --git a/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts b/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts
index 77f2498..570b50a 100644
--- a/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts
+++ b/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts
@@ -442,6 +442,7 @@
   invalidateGroupsCache(): void {},
   invalidateReposCache(): void {},
   invalidateAccountsDetailCache(): void {},
+  invalidateAccountsEmailCache(): void {},
   probePath(): Promise<boolean> {
     return Promise.resolve(true);
   },
diff --git a/polygerrit-ui/app/test/test-data-generators.ts b/polygerrit-ui/app/test/test-data-generators.ts
index 3829f57..7d666e8 100644
--- a/polygerrit-ui/app/test/test-data-generators.ts
+++ b/polygerrit-ui/app/test/test-data-generators.ts
@@ -712,6 +712,7 @@
     email_strategy: EmailStrategy.ENABLED,
     allow_browser_notifications: true,
     allow_suggest_code_while_commenting: true,
+    allow_autocompleting_comments: true,
   };
 }
 
diff --git a/polygerrit-ui/app/types/common.ts b/polygerrit-ui/app/types/common.ts
index 4dd965c..072a872 100644
--- a/polygerrit-ui/app/types/common.ts
+++ b/polygerrit-ui/app/types/common.ts
@@ -1344,6 +1344,7 @@
   email_format?: EmailFormat;
   allow_browser_notifications?: boolean;
   allow_suggest_code_while_commenting?: boolean;
+  allow_autocompleting_comments?: boolean;
   diff_page_sidebar?: DiffPageSidebar;
 }
 
diff --git a/polygerrit-ui/app/utils/account-util.ts b/polygerrit-ui/app/utils/account-util.ts
index 0853941..b93acc6 100644
--- a/polygerrit-ui/app/utils/account-util.ts
+++ b/polygerrit-ui/app/utils/account-util.ts
@@ -140,10 +140,10 @@
 
 export function isDetailedAccount(account?: AccountInfo) {
   // In case ChangeInfo is requested without DetailedAccount option, the
-  // reviewer entry is returned as just {_account_id: 123}
-  // This object should also be treated as not detailed account if they have
-  // an AccountId and no email
-  return !!account?.email && !!account?._account_id;
+  // reviewer entry is returned as just {_account_id: 123}.
+  // At least a name or an email must be set for the account to be treated as
+  // "detailed".
+  return (!!account?.email || !!account?.name) && !!account?._account_id;
 }
 
 /**
diff --git a/polygerrit-ui/app/utils/account-util_test.ts b/polygerrit-ui/app/utils/account-util_test.ts
index 72fa791..b1ee50e 100644
--- a/polygerrit-ui/app/utils/account-util_test.ts
+++ b/polygerrit-ui/app/utils/account-util_test.ts
@@ -263,6 +263,7 @@
   test('isDetailedAccount', () => {
     assert.isFalse(isDetailedAccount({_account_id: 12345 as AccountId}));
     assert.isFalse(isDetailedAccount({email: 'abcd' as EmailAddress}));
+    assert.isFalse(isDetailedAccount({name: 'Kermit'}));
 
     assert.isTrue(
       isDetailedAccount({
@@ -270,6 +271,12 @@
         email: 'abcd' as EmailAddress,
       })
     );
+    assert.isTrue(
+      isDetailedAccount({
+        _account_id: 12345 as AccountId,
+        name: 'Kermit',
+      })
+    );
   });
 
   test('fails gracefully when all is not included', async () => {
diff --git a/polygerrit-ui/app/utils/autocomplete-cache.ts b/polygerrit-ui/app/utils/autocomplete-cache.ts
new file mode 100644
index 0000000..c8077ab
--- /dev/null
+++ b/polygerrit-ui/app/utils/autocomplete-cache.ts
@@ -0,0 +1,79 @@
+/**
+ * @license
+ * Copyright 2024 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+export interface AutocompletionContext {
+  draftContent: string;
+  draftContentLength?: number;
+  commentCompletion: string;
+  commentCompletionLength?: number;
+
+  isFullCommentPrediction?: boolean;
+  draftInSyncWithSuggestionLength?: number;
+  modelVersion?: string;
+  requestDurationMs?: number;
+
+  commentId?: string;
+  commentNumber?: number;
+  filePath?: string;
+  fileExtension?: string;
+
+  similarCharacters?: number;
+  maxSimilarCharacters?: number;
+  acceptedSuggestionsCount?: number;
+  totalAcceptedCharacters?: number;
+  savedDraftLength?: number;
+}
+
+/**
+ * Caching for autocompleting text, e.g. comments.
+ *
+ * If the user continues typing text that matches the completion hint, then keep the hint.
+ *
+ * If the user backspaces, then continue using previous hint.
+ */
+export class AutocompleteCache {
+  /**
+   * We are using an ordered list instead of a map here, because we want to evict the oldest
+   * entries, if the capacity is exceeded. And we want to prefer newer entries over older
+   * entries, if both match the criteria for being reused.
+   */
+  private cache: AutocompletionContext[] = [];
+
+  constructor(private readonly capacity = 10) {}
+
+  get(content: string): AutocompletionContext | undefined {
+    if (content === '') return undefined;
+    for (let i = this.cache.length - 1; i >= 0; i--) {
+      const cachedContext = this.cache[i];
+      const completionContent = cachedContext.draftContent;
+      const completionHint = cachedContext.commentCompletion;
+      const completionFull = completionContent + completionHint;
+      if (completionContent.length > content.length) continue;
+      if (!completionFull.startsWith(content)) continue;
+      if (completionFull === content) continue;
+      const hint = completionFull.substring(content.length);
+      return {
+        ...cachedContext,
+        draftContent: content,
+        commentCompletion: hint,
+        draftInSyncWithSuggestionLength:
+          content.length - completionContent.length,
+      };
+    }
+    return undefined;
+  }
+
+  set(context: AutocompletionContext) {
+    const index = this.cache.findIndex(
+      c => c.draftContent === context.draftContent
+    );
+    if (index !== -1) {
+      this.cache.splice(index, 1);
+    } else if (this.cache.length >= this.capacity) {
+      this.cache.shift();
+    }
+    this.cache.push(context);
+  }
+}
diff --git a/polygerrit-ui/app/utils/autocomplete-cache_test.ts b/polygerrit-ui/app/utils/autocomplete-cache_test.ts
new file mode 100644
index 0000000..970436b
--- /dev/null
+++ b/polygerrit-ui/app/utils/autocomplete-cache_test.ts
@@ -0,0 +1,89 @@
+/**
+ * @license
+ * Copyright 2024 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import {AutocompleteCache} from './autocomplete-cache';
+import {assert} from '@open-wc/testing';
+
+suite('AutocompleteCache', () => {
+  let cache: AutocompleteCache;
+
+  setup(() => {
+    cache = new AutocompleteCache();
+  });
+
+  const cacheSet = (draftContent: string, commentCompletion: string) => {
+    cache.set({draftContent, commentCompletion});
+  };
+
+  const assertCacheEqual = (
+    draftContent: string,
+    expectedCommentCompletion?: string
+  ) => {
+    assert.equal(
+      cache.get(draftContent)?.commentCompletion,
+      expectedCommentCompletion
+    );
+  };
+
+  test('should get and set values', () => {
+    cacheSet('foo', 'bar');
+    assertCacheEqual('foo', 'bar');
+  });
+
+  test('should return undefined for empty content string', () => {
+    cacheSet('foo', 'bar');
+    assertCacheEqual('', undefined);
+  });
+
+  test('should return a value, if completion content+hint start with content', () => {
+    cacheSet('foo', 'bar');
+    assertCacheEqual('foo', 'bar');
+    assertCacheEqual('foob', 'ar');
+    assertCacheEqual('fooba', 'r');
+    assertCacheEqual('foobar', undefined);
+  });
+
+  test('should not return a value, if content is shorter than completion content', () => {
+    cacheSet('foo', 'bar');
+    assertCacheEqual('f', undefined);
+    assertCacheEqual('fo', undefined);
+  });
+
+  test('should not get values that are not set', () => {
+    assertCacheEqual('foo', undefined);
+  });
+
+  test('should not return an empty completion, if content equals completion content+hint', () => {
+    cacheSet('foo', 'bar');
+    assertCacheEqual('foobar', undefined);
+  });
+
+  test('skips over the first entry, but returns the second entry', () => {
+    cacheSet('foobar', 'bang');
+    cacheSet('foo', 'bar');
+    assertCacheEqual('foobar', 'bang');
+  });
+
+  test('replaces entries', () => {
+    cacheSet('foo', 'bar');
+    cacheSet('foo', 'baz');
+    assertCacheEqual('foo', 'baz');
+  });
+
+  test('prefers newer entries, but also returns older entries', () => {
+    cacheSet('foo', 'bar');
+    assertCacheEqual('foob', 'ar');
+    cacheSet('foob', 'arg');
+    assertCacheEqual('foob', 'arg');
+    assertCacheEqual('foo', 'bar');
+  });
+
+  test('capacity', () => {
+    cache = new AutocompleteCache(1);
+    cacheSet('foo', 'bar');
+    cacheSet('boom', 'bang');
+    assertCacheEqual('foo', undefined);
+  });
+});
diff --git a/polygerrit-ui/app/utils/deep-util.ts b/polygerrit-ui/app/utils/deep-util.ts
index eca528e..3e41e61 100644
--- a/polygerrit-ui/app/utils/deep-util.ts
+++ b/polygerrit-ui/app/utils/deep-util.ts
@@ -82,7 +82,7 @@
 /**
  * @param obj Object
  */
-export function deepClone(obj?: object) {
-  if (!obj) return undefined;
-  return JSON.parse(JSON.stringify(obj));
+export function deepClone<T>(obj: T): T {
+  if (!obj) throw new Error('undefined object for deepClone');
+  return JSON.parse(JSON.stringify(obj)) as T;
 }
diff --git a/polygerrit-ui/app/utils/string-util.ts b/polygerrit-ui/app/utils/string-util.ts
index 81dcde1..abc5529 100644
--- a/polygerrit-ui/app/utils/string-util.ts
+++ b/polygerrit-ui/app/utils/string-util.ts
@@ -115,3 +115,42 @@
     fileName: fileNameSection,
   };
 }
+
+/**
+ * Computes the Levenshtein edit distance between two strings.
+ */
+export function levenshteinDistance(str1: string, str2: string): number {
+  const m = str1.length;
+  const n = str2.length;
+
+  // Create a matrix to store edit distances
+  const dp: number[][] = Array.from({length: m + 1}, () =>
+    Array(n + 1).fill(0)
+  );
+
+  // Initialize first row and column with base cases
+  for (let i = 0; i <= m; i++) {
+    dp[i][0] = i;
+  }
+  for (let j = 0; j <= n; j++) {
+    dp[0][j] = j;
+  }
+
+  // Calculate edit distances for all substrings
+  for (let i = 1; i <= m; i++) {
+    for (let j = 1; j <= n; j++) {
+      if (str1[i - 1] === str2[j - 1]) {
+        dp[i][j] = dp[i - 1][j - 1];
+      } else {
+        dp[i][j] = Math.min(
+          dp[i - 1][j] + 1, // Deletion
+          dp[i][j - 1] + 1, // Insertion
+          dp[i - 1][j - 1] + 1 // Substitution
+        );
+      }
+    }
+  }
+
+  // Return the final edit distance
+  return dp[m][n];
+}
diff --git a/polygerrit-ui/app/yarn.lock b/polygerrit-ui/app/yarn.lock
index b2f722f..a8f10e2 100644
--- a/polygerrit-ui/app/yarn.lock
+++ b/polygerrit-ui/app/yarn.lock
@@ -610,18 +610,24 @@
   resolved "https://registry.yarnpkg.com/highlight.js/-/highlight.js-10.7.3.tgz#697272e3991356e40c3cac566a74eef681756531"
   integrity sha512-tzcUFauisWKNHaRkN4Wjl/ZA07gENAjFl3J/c480dprkGTg5EQstgaNFqBfUqCq54kZRIEcreTsAgF/m2quD7A==
 
-"highlight.js@^11.5.0 || ^10.4.1", highlight.js@^11.9.0:
+highlight.js@^11.9.0, "highlight.js@^11.9.0 || ^10.4.1":
   version "11.9.0"
   resolved "https://registry.yarnpkg.com/highlight.js/-/highlight.js-11.9.0.tgz#04ab9ee43b52a41a047432c8103e2158a1b8b5b0"
   integrity sha512-fJ7cW7fQGCYAkgv4CPfwFHrfd/cLS4Hau96JuJ+ZTOWhjnhoeN1ub1tFmALm/+lW5z4WCAuAV9bm05AP0mS6Gw==
 
-"highlightjs-closure-templates@https://github.com/highlightjs/highlightjs-closure-templates":
+"highlightjs-closure-templates@https://github.com/highlightjs/highlightjs-closure-templates#02fb0646e0499084f96a99b8c6f4a0d7bd1d33ba":
   version "0.0.1"
-  resolved "https://github.com/highlightjs/highlightjs-closure-templates#7922b1e68def8b10199e186bb679600de3ebb711"
+  resolved "https://github.com/highlightjs/highlightjs-closure-templates#02fb0646e0499084f96a99b8c6f4a0d7bd1d33ba"
   dependencies:
-    highlight.js "^11.5.0 || ^10.4.1"
+    highlight.js "^11.9.0 || ^10.4.1"
 
-"highlightjs-structured-text@https://github.com/highlightjs/highlightjs-structured-text":
+"highlightjs-epp@https://github.com/highlightjs/highlightjs-epp#9f9e1a92f37c217c68899c7d3bdccb4d134681b9":
+  version "0.0.1"
+  resolved "https://github.com/highlightjs/highlightjs-epp#9f9e1a92f37c217c68899c7d3bdccb4d134681b9"
+  dependencies:
+    highlight.js "^11.9.0"
+
+"highlightjs-structured-text@https://github.com/highlightjs/highlightjs-structured-text#e68dd7aa829529fb6c40d6287585f43273605a9e":
   version "1.4.9"
   resolved "https://github.com/highlightjs/highlightjs-structured-text#e68dd7aa829529fb6c40d6287585f43273605a9e"
   dependencies:
diff --git a/proto/entities.proto b/proto/entities.proto
index be04e97..6d5ac04 100644
--- a/proto/entities.proto
+++ b/proto/entities.proto
@@ -277,7 +277,7 @@
 // Next ID: 2
 message ObjectId {
   // Hex string representation of the ID.
-  optional string name = 1;
+  optional string name = 1 [default="0000000000000000000000000000000000000000"];
 }
 
 // Serialized form of a continuation token used for pagination.
@@ -289,7 +289,7 @@
 // Proto representation of the User preferences classes
 // Next ID: 4
 message UserPreferences {
-  // Next ID: 24
+  // Next ID: 26
   message GeneralPreferencesInfo {
     // Number of changes to show in a screen.
     optional int32 changes_per_page = 1 [default = 25];
@@ -368,6 +368,8 @@
 
     repeated string change_table = 18;
     optional bool allow_browser_notifications = 19 [default = true];
+    optional bool allow_suggest_code_while_commenting = 24 [default = true];
+    optional bool allow_autocompleting_comments = 25 [default = true];
     optional string diff_page_sidebar = 23 [default = "NONE"];
   }
   optional GeneralPreferencesInfo general_preferences_info = 1;
@@ -453,11 +455,11 @@
     optional Side side = 2 [default = REVISION];
     message Range {
       // 1-based
-      optional int32 start_line = 1;
+      optional int32 start_line = 1 [default = 1];
       // 0-based
       optional int32 start_char = 2;
       // 1-based
-      optional int32 end_line = 3;
+      optional int32 end_line = 3 [default = 1];
       // 0-based
       optional int32 end_char = 4;
     }
@@ -466,7 +468,7 @@
     // number is identical to the range's end line.
     optional Range position_range = 3;
     // 1-based
-    optional int32 line_number = 4;
+    optional int32 line_number = 4 [default = 1];
   }
 
   // If not set, the comment is on the patchset level.
@@ -488,4 +490,4 @@
   optional fixed64 written_on_millis = 11;
   // Required.
   optional string server_id = 12;
-}
\ No newline at end of file
+}
diff --git a/resources/com/google/gerrit/server/mime/mime-types.properties b/resources/com/google/gerrit/server/mime/mime-types.properties
index 642ef474..432d088 100644
--- a/resources/com/google/gerrit/server/mime/mime-types.properties
+++ b/resources/com/google/gerrit/server/mime/mime-types.properties
@@ -63,6 +63,7 @@
 el = text/x-common-lisp
 elm = text/x-elm
 ejs = application/x-ejs
+epp = application/x-epp
 erb = application/x-erb
 erl = text/x-erlang
 es6 = text/jsx
diff --git a/tools/bzl/pkg_war.bzl b/tools/bzl/pkg_war.bzl
index 4792de2..52fa1dd 100644
--- a/tools/bzl/pkg_war.bzl
+++ b/tools/bzl/pkg_war.bzl
@@ -14,7 +14,8 @@
 
 # War packaging.
 
-load("//tools:deps.bzl", "AUTO_FACTORY_VERSION", "AUTO_VALUE_GSON_VERSION", "AUTO_VALUE_VERSION")
+load("//tools:deps.bzl", "AUTO_VALUE_GSON_VERSION")
+load("//tools:nongoogle.bzl", "AUTO_FACTORY_VERSION", "AUTO_VALUE_VERSION")
 
 jar_filetype = [".jar"]
 
diff --git a/tools/deps.bzl b/tools/deps.bzl
index d056483..bc37010 100644
--- a/tools/deps.bzl
+++ b/tools/deps.bzl
@@ -11,9 +11,6 @@
 MAIL_VERS = "1.6.0"
 MIME4J_VERS = "0.8.1"
 OW2_VERS = "9.2"
-AUTO_COMMON_VERSION = "1.2.1"
-AUTO_FACTORY_VERSION = "1.0.1"
-AUTO_VALUE_VERSION = "1.10.4"
 AUTO_VALUE_GSON_VERSION = "1.3.1"
 PROLOG_VERS = "1.4.4"
 PROLOG_REPO = GERRIT
@@ -90,12 +87,6 @@
     )
 
     maven_jar(
-        name = "gson",
-        artifact = "com.google.code.gson:gson:2.9.0",
-        sha1 = "8a1167e089096758b49f9b34066ef98b2f4b37aa",
-    )
-
-    maven_jar(
         name = "caffeine",
         artifact = "com.github.ben-manes.caffeine:caffeine:" + CAFFEINE_VERS,
         sha1 = "0a17ed335e0ce2d337750772c0709b79af35a842",
@@ -283,36 +274,6 @@
     )
 
     maven_jar(
-        name = "auto-common",
-        artifact = "com.google.auto:auto-common:" + AUTO_COMMON_VERSION,
-        sha1 = "f6da26895f759010f5f170c8044e84c1b17ef83e",
-    )
-
-    maven_jar(
-        name = "auto-factory",
-        artifact = "com.google.auto.factory:auto-factory:" + AUTO_FACTORY_VERSION,
-        sha1 = "f81ece06b6525085da217cd900116f44caafe877",
-    )
-
-    maven_jar(
-        name = "auto-service-annotations",
-        artifact = "com.google.auto.service:auto-service-annotations:" + AUTO_FACTORY_VERSION,
-        sha1 = "ac86dacc0eb9285ea9d42eee6aad8629ca3a7432",
-    )
-
-    maven_jar(
-        name = "auto-value",
-        artifact = "com.google.auto.value:auto-value:" + AUTO_VALUE_VERSION,
-        sha1 = "90f9629eaa123f88551cc26a64bc386967ee24cc",
-    )
-
-    maven_jar(
-        name = "auto-value-annotations",
-        artifact = "com.google.auto.value:auto-value-annotations:" + AUTO_VALUE_VERSION,
-        sha1 = "9679de8286eb0a151db6538ba297a8951c4a1224",
-    )
-
-    maven_jar(
         name = "auto-value-gson-runtime",
         artifact = "com.ryanharter.auto.value:auto-value-gson-runtime:" + AUTO_VALUE_GSON_VERSION,
         sha1 = "addda2ae6cce9f855788274df5de55dde4de7b71",
diff --git a/tools/nongoogle.bzl b/tools/nongoogle.bzl
index ac3f668..e185141 100644
--- a/tools/nongoogle.bzl
+++ b/tools/nongoogle.bzl
@@ -7,6 +7,12 @@
 load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
 load("//tools/bzl:maven_jar.bzl", "maven_jar")
 
+AUTO_COMMON_VERSION = "1.2.1"
+
+AUTO_FACTORY_VERSION = "1.0.1"
+
+AUTO_VALUE_VERSION = "1.10.4"
+
 GUAVA_VERSION = "33.0.0-jre"
 
 GUAVA_BIN_SHA1 = "161ba27964a62f241533807a46b8711b13c1d94b"
@@ -182,6 +188,36 @@
     # no concern about version skew.
 
     maven_jar(
+        name = "auto-common",
+        artifact = "com.google.auto:auto-common:" + AUTO_COMMON_VERSION,
+        sha1 = "f6da26895f759010f5f170c8044e84c1b17ef83e",
+    )
+
+    maven_jar(
+        name = "auto-factory",
+        artifact = "com.google.auto.factory:auto-factory:" + AUTO_FACTORY_VERSION,
+        sha1 = "f81ece06b6525085da217cd900116f44caafe877",
+    )
+
+    maven_jar(
+        name = "auto-service-annotations",
+        artifact = "com.google.auto.service:auto-service-annotations:" + AUTO_FACTORY_VERSION,
+        sha1 = "ac86dacc0eb9285ea9d42eee6aad8629ca3a7432",
+    )
+
+    maven_jar(
+        name = "auto-value",
+        artifact = "com.google.auto.value:auto-value:" + AUTO_VALUE_VERSION,
+        sha1 = "90f9629eaa123f88551cc26a64bc386967ee24cc",
+    )
+
+    maven_jar(
+        name = "auto-value-annotations",
+        artifact = "com.google.auto.value:auto-value-annotations:" + AUTO_VALUE_VERSION,
+        sha1 = "9679de8286eb0a151db6538ba297a8951c4a1224",
+    )
+
+    maven_jar(
         name = "error-prone-annotations",
         artifact = "com.google.errorprone:error_prone_annotations:2.22.0",
         sha1 = "bfb9e4281a4cea34f0ec85b3acd47621cfab35b4",
@@ -252,6 +288,12 @@
         sha1 = "6e9ccb00926325c7a9293ed05a2eaf56ea15d60e",
     )
 
+    maven_jar(
+        name = "gson",
+        artifact = "com.google.code.gson:gson:2.10.1",
+        sha1 = "b3add478d4382b78ea20b1671390a858002feb6c",
+    )
+
     # Test-only dependencies below.
     maven_jar(
         name = "cglib-3_2",