diff --git a/src/applications/harbormaster/engine/HarbormasterBuildEngine.php b/src/applications/harbormaster/engine/HarbormasterBuildEngine.php
index 78b986fa83..15bd487391 100644
--- a/src/applications/harbormaster/engine/HarbormasterBuildEngine.php
+++ b/src/applications/harbormaster/engine/HarbormasterBuildEngine.php
@@ -1,400 +1,452 @@
 <?php
 
 /**
  * Moves a build forward by queuing build tasks, canceling or restarting the
  * build, or failing it in response to task failures.
  */
 final class HarbormasterBuildEngine extends Phobject {
 
   private $build;
   private $viewer;
   private $newBuildTargets = array();
   private $forceBuildableUpdate;
 
   public function setForceBuildableUpdate($force_buildable_update) {
     $this->forceBuildableUpdate = $force_buildable_update;
     return $this;
   }
 
   public function shouldForceBuildableUpdate() {
     return $this->forceBuildableUpdate;
   }
 
   public function queueNewBuildTarget(HarbormasterBuildTarget $target) {
     $this->newBuildTargets[] = $target;
     return $this;
   }
 
   public function getNewBuildTargets() {
     return $this->newBuildTargets;
   }
 
   public function setViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
     return $this;
   }
 
   public function getViewer() {
     return $this->viewer;
   }
 
   public function setBuild(HarbormasterBuild $build) {
     $this->build = $build;
     return $this;
   }
 
   public function getBuild() {
     return $this->build;
   }
 
   public function continueBuild() {
     $build = $this->getBuild();
 
     $lock_key = 'harbormaster.build:'.$build->getID();
     $lock = PhabricatorGlobalLock::newLock($lock_key)->lock(15);
 
     $build->reload();
     $old_status = $build->getBuildStatus();
 
     try {
       $this->updateBuild($build);
     } catch (Exception $ex) {
       // If any exception is raised, the build is marked as a failure and the
       // exception is re-thrown (this ensures we don't leave builds in an
       // inconsistent state).
       $build->setBuildStatus(HarbormasterBuild::STATUS_ERROR);
       $build->save();
 
       $lock->unlock();
       throw $ex;
     }
 
     $lock->unlock();
 
     // NOTE: We queue new targets after releasing the lock so that in-process
     // execution via `bin/harbormaster` does not reenter the locked region.
     foreach ($this->getNewBuildTargets() as $target) {
       $task = PhabricatorWorker::scheduleTask(
         'HarbormasterTargetWorker',
         array(
           'targetID' => $target->getID(),
         ));
     }
 
     // If the build changed status, we might need to update the overall status
     // on the buildable.
     $new_status = $build->getBuildStatus();
     if ($new_status != $old_status || $this->shouldForceBuildableUpdate()) {
       $this->updateBuildable($build->getBuildable());
     }
   }
 
   private function updateBuild(HarbormasterBuild $build) {
     if (($build->getBuildStatus() == HarbormasterBuild::STATUS_PENDING) ||
         ($build->isRestarting())) {
       $this->destroyBuildTargets($build);
       $build->setBuildStatus(HarbormasterBuild::STATUS_BUILDING);
       $build->save();
     }
 
     if ($build->isResuming()) {
       $build->setBuildStatus(HarbormasterBuild::STATUS_BUILDING);
       $build->save();
     }
 
     if ($build->isStopping() && !$build->isComplete()) {
       $build->setBuildStatus(HarbormasterBuild::STATUS_STOPPED);
       $build->save();
     }
 
     $build->deleteUnprocessedCommands();
 
     if ($build->getBuildStatus() == HarbormasterBuild::STATUS_BUILDING) {
       $this->updateBuildSteps($build);
     }
   }
 
   private function destroyBuildTargets(HarbormasterBuild $build) {
     $targets = id(new HarbormasterBuildTargetQuery())
       ->setViewer($this->getViewer())
       ->withBuildPHIDs(array($build->getPHID()))
       ->execute();
 
     if (!$targets) {
       return;
     }
 
     $target_phids = mpull($targets, 'getPHID');
 
     $artifacts = id(new HarbormasterBuildArtifactQuery())
       ->setViewer($this->getViewer())
       ->withBuildTargetPHIDs($target_phids)
       ->execute();
 
     foreach ($artifacts as $artifact) {
       $artifact->delete();
     }
 
     foreach ($targets as $target) {
       $target->delete();
     }
   }
 
   private function updateBuildSteps(HarbormasterBuild $build) {
     $targets = id(new HarbormasterBuildTargetQuery())
       ->setViewer($this->getViewer())
       ->withBuildPHIDs(array($build->getPHID()))
       ->execute();
 
     $this->updateWaitingTargets($targets);
 
     $targets = mgroup($targets, 'getBuildStepPHID');
 
     $steps = id(new HarbormasterBuildStepQuery())
       ->setViewer($this->getViewer())
       ->withBuildPlanPHIDs(array($build->getBuildPlan()->getPHID()))
       ->execute();
 
     // Identify steps which are in various states.
 
     $queued = array();
     $underway = array();
     $waiting = array();
     $complete = array();
     $failed = array();
     foreach ($steps as $step) {
       $step_targets = idx($targets, $step->getPHID(), array());
 
       if ($step_targets) {
         $is_queued = false;
 
         $is_underway = false;
         foreach ($step_targets as $target) {
           if ($target->isUnderway()) {
             $is_underway = true;
             break;
           }
         }
 
         $is_waiting = false;
         foreach ($step_targets as $target) {
           if ($target->isWaiting()) {
             $is_waiting = true;
             break;
           }
         }
 
         $is_complete = true;
         foreach ($step_targets as $target) {
           if (!$target->isComplete()) {
             $is_complete = false;
             break;
           }
         }
 
         $is_failed = false;
         foreach ($step_targets as $target) {
           if ($target->isFailed()) {
             $is_failed = true;
             break;
           }
         }
       } else {
         $is_queued = true;
         $is_underway = false;
         $is_waiting = false;
         $is_complete = false;
         $is_failed = false;
       }
 
       if ($is_queued) {
         $queued[$step->getPHID()] = true;
       }
 
       if ($is_underway) {
         $underway[$step->getPHID()] = true;
       }
 
       if ($is_waiting) {
         $waiting[$step->getPHID()] = true;
       }
 
       if ($is_complete) {
         $complete[$step->getPHID()] = true;
       }
 
       if ($is_failed) {
         $failed[$step->getPHID()] = true;
       }
     }
 
     // If any step failed, fail the whole build, then bail.
     if (count($failed)) {
       $build->setBuildStatus(HarbormasterBuild::STATUS_FAILED);
       $build->save();
       return;
     }
 
     // If every step is complete, we're done with this build. Mark it passed
     // and bail.
     if (count($complete) == count($steps)) {
       $build->setBuildStatus(HarbormasterBuild::STATUS_PASSED);
       $build->save();
       return;
     }
 
     // Identify all the steps which are ready to run (because all their
     // depdendencies are complete).
 
     $previous_step = null;
     $runnable = array();
     foreach ($steps as $step) {
       // TODO: For now, we're hard coding sequential dependencies into build
       // steps. In the future, we can be smart about this instead.
 
       if ($previous_step) {
         $dependencies = array($previous_step);
       } else {
         $dependencies = array();
       }
 
       if (isset($queued[$step->getPHID()])) {
         $can_run = true;
         foreach ($dependencies as $dependency) {
           if (empty($complete[$dependency->getPHID()])) {
             $can_run = false;
             break;
           }
         }
 
         if ($can_run) {
           $runnable[] = $step;
         }
       }
 
       $previous_step = $step;
     }
 
     if (!$runnable && !$waiting && !$underway) {
       // TODO: This means the build is deadlocked, probably? It should not
       // normally be possible yet, but we should communicate it more clearly.
       $build->setBuildStatus(HarbormasterBuild::STATUS_FAILED);
       $build->save();
       return;
     }
 
     foreach ($runnable as $runnable_step) {
       $target = HarbormasterBuildTarget::initializeNewBuildTarget(
         $build,
         $runnable_step,
         $build->retrieveVariablesFromBuild());
       $target->save();
 
       $this->queueNewBuildTarget($target);
     }
 
   }
 
 
   /**
    * Process messages which were sent to these targets, kicking applicable
    * targets out of "Waiting" and into either "Passed" or "Failed".
    *
    * @param list<HarbormasterBuildTarget> List of targets to process.
    * @return void
    */
   private function updateWaitingTargets(array $targets) {
     assert_instances_of($targets, 'HarbormasterBuildTarget');
 
     // We only care about messages for targets which are actually in a waiting
     // state.
     $waiting_targets = array();
     foreach ($targets as $target) {
       if ($target->isWaiting()) {
         $waiting_targets[$target->getPHID()] = $target;
       }
     }
 
     if (!$waiting_targets) {
       return;
     }
 
     $messages = id(new HarbormasterBuildMessageQuery())
       ->setViewer($this->getViewer())
       ->withBuildTargetPHIDs(array_keys($waiting_targets))
       ->withConsumed(false)
       ->execute();
 
     foreach ($messages as $message) {
       $target = $waiting_targets[$message->getBuildTargetPHID()];
 
       $new_status = null;
       switch ($message->getType()) {
         case 'pass':
           $new_status = HarbormasterBuildTarget::STATUS_PASSED;
           break;
         case 'fail':
           $new_status = HarbormasterBuildTarget::STATUS_FAILED;
           break;
       }
 
       if ($new_status !== null) {
         $message->setIsConsumed(true);
         $message->save();
 
         $target->setTargetStatus($new_status);
         $target->save();
       }
     }
   }
 
 
   /**
    * Update the overall status of the buildable this build is attached to.
    *
    * After a build changes state (for example, passes or fails) it may affect
    * the overall state of the associated buildable. Compute the new aggregate
    * state and save it on the buildable.
    *
    * @param   HarbormasterBuild The buildable to update.
    * @return  void
    */
   private function updateBuildable(HarbormasterBuildable $buildable) {
+    $viewer = $this->getViewer();
+
     $lock_key = 'harbormaster.buildable:'.$buildable->getID();
     $lock = PhabricatorGlobalLock::newLock($lock_key)->lock(15);
 
     $buildable = id(new HarbormasterBuildableQuery())
-      ->setViewer($this->getViewer())
+      ->setViewer($viewer)
       ->withIDs(array($buildable->getID()))
       ->needBuilds(true)
       ->executeOne();
 
     $all_pass = true;
     $any_fail = false;
     foreach ($buildable->getBuilds() as $build) {
       if ($build->getBuildStatus() != HarbormasterBuild::STATUS_PASSED) {
         $all_pass = false;
       }
       if ($build->getBuildStatus() == HarbormasterBuild::STATUS_FAILED ||
           $build->getBuildStatus() == HarbormasterBuild::STATUS_ERROR) {
         $any_fail = true;
       }
     }
 
     if ($any_fail) {
       $new_status = HarbormasterBuildable::STATUS_FAILED;
     } else if ($all_pass) {
       $new_status = HarbormasterBuildable::STATUS_PASSED;
     } else {
       $new_status = HarbormasterBuildable::STATUS_BUILDING;
     }
 
-    if ($buildable->getBuildableStatus() != $new_status) {
+    $old_status = $buildable->getBuildableStatus();
+    $did_update = ($old_status != $new_status);
+    if ($did_update) {
       $buildable->setBuildableStatus($new_status);
       $buildable->save();
     }
 
     $lock->unlock();
+
+    // If we changed the buildable status, try to post a transaction to the
+    // object about it. We can safely do this outside of the locked region.
+
+    // NOTE: We only post transactions for automatic buildables, not for
+    // manual ones: manual builds are test builds, whoever is doing tests
+    // can look at the results themselves, and other users generally don't
+    // care about the outcome.
+
+    if ($did_update && !$buildable->getIsManualBuildable()) {
+
+      $object = id(new PhabricatorObjectQuery())
+        ->setViewer($viewer)
+        ->withPHIDs(array($buildable->getBuildablePHID()))
+        ->executeOne();
+
+      if ($object instanceof PhabricatorApplicationTransactionInterface) {
+        $template = $object->getApplicationTransactionTemplate();
+        if ($template) {
+          $template
+            ->setTransactionType(PhabricatorTransactions::TYPE_BUILDABLE)
+            ->setMetadataValue(
+              'harbormaster:buildablePHID',
+              $buildable->getPHID())
+            ->setOldValue($old_status)
+            ->setNewValue($new_status);
+
+          $harbormaster_phid = id(new PhabricatorApplicationHarbormaster())
+            ->getPHID();
+
+          $daemon_source = PhabricatorContentSource::newForSource(
+            PhabricatorContentSource::SOURCE_DAEMON,
+            array());
+
+          $editor = $object->getApplicationTransactionEditor()
+            ->setActor($viewer)
+            ->setActingAsPHID($harbormaster_phid)
+            ->setContentSource($daemon_source)
+            ->setContinueOnNoEffect(true)
+            ->setContinueOnMissingFields(true);
+
+          $editor->applyTransactions(
+            $object->getApplicationTransactionObject(),
+            array($template));
+        }
+      }
+    }
+
   }
 
 }
diff --git a/src/applications/metamta/storage/PhabricatorMetaMTAMail.php b/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
index 4e1c17ce12..9899226ec9 100644
--- a/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
+++ b/src/applications/metamta/storage/PhabricatorMetaMTAMail.php
@@ -1,877 +1,890 @@
 <?php
 
 /**
  * @task recipients   Managing Recipients
  */
 final class PhabricatorMetaMTAMail extends PhabricatorMetaMTADAO {
 
   const STATUS_QUEUE = 'queued';
   const STATUS_SENT  = 'sent';
   const STATUS_FAIL  = 'fail';
   const STATUS_VOID  = 'void';
 
   const RETRY_DELAY   = 5;
 
   protected $parameters;
   protected $status;
   protected $message;
   protected $relatedPHID;
 
   private $excludePHIDs = array();
   private $overrideNoSelfMail = false;
   private $recipientExpansionMap;
 
   public function __construct() {
 
     $this->status     = self::STATUS_QUEUE;
     $this->parameters = array();
 
     parent::__construct();
   }
 
   public function getConfiguration() {
     return array(
       self::CONFIG_SERIALIZATION => array(
         'parameters'  => self::SERIALIZATION_JSON,
       ),
     ) + parent::getConfiguration();
   }
 
   protected function setParam($param, $value) {
     $this->parameters[$param] = $value;
     return $this;
   }
 
   protected function getParam($param, $default = null) {
     return idx($this->parameters, $param, $default);
   }
 
   /**
    * Set tags (@{class:MetaMTANotificationType} constants) which identify the
    * content of this mail in a general way. These tags are used to allow users
    * to opt out of receiving certain types of mail, like updates when a task's
    * projects change.
    *
    * @param list<const> List of @{class:MetaMTANotificationType} constants.
    * @return this
    */
   public function setMailTags(array $tags) {
     $this->setParam('mailtags', array_unique($tags));
     return $this;
   }
 
   public function getMailTags() {
     return $this->getParam('mailtags', array());
   }
 
   /**
    * In Gmail, conversations will be broken if you reply to a thread and the
    * server sends back a response without referencing your Message-ID, even if
    * it references a Message-ID earlier in the thread. To avoid this, use the
    * parent email's message ID explicitly if it's available. This overwrites the
    * "In-Reply-To" and "References" headers we would otherwise generate. This
    * needs to be set whenever an action is triggered by an email message. See
    * T251 for more details.
    *
    * @param   string The "Message-ID" of the email which precedes this one.
    * @return  this
    */
   public function setParentMessageID($id) {
     $this->setParam('parent-message-id', $id);
     return $this;
   }
 
   public function getParentMessageID() {
     return $this->getParam('parent-message-id');
   }
 
   public function getSubject() {
     return $this->getParam('subject');
   }
 
   public function addTos(array $phids) {
     $phids = array_unique($phids);
     $this->setParam('to', $phids);
     return $this;
   }
 
   public function addRawTos(array $raw_email) {
     $this->setParam('raw-to', $raw_email);
     return $this;
   }
 
   public function addCCs(array $phids) {
     $phids = array_unique($phids);
     $this->setParam('cc', $phids);
     return $this;
   }
 
   public function setExcludeMailRecipientPHIDs($exclude) {
     $this->excludePHIDs = $exclude;
     return $this;
   }
   private function getExcludeMailRecipientPHIDs() {
     return $this->excludePHIDs;
   }
 
   public function getOverrideNoSelfMailPreference() {
     return $this->overrideNoSelfMail;
   }
 
   public function setOverrideNoSelfMailPreference($override) {
     $this->overrideNoSelfMail = $override;
     return $this;
   }
 
   public function getTranslation(array $objects) {
     $default_translation = PhabricatorEnv::getEnvConfig('translation.provider');
     $return = null;
     $recipients = array_merge(
       idx($this->parameters, 'to', array()),
       idx($this->parameters, 'cc', array()));
     foreach (array_select_keys($objects, $recipients) as $object) {
       $translation = null;
       if ($object instanceof PhabricatorUser) {
         $translation = $object->getTranslation();
       }
       if (!$translation) {
         $translation = $default_translation;
       }
       if ($return && $translation != $return) {
         return $default_translation;
       }
       $return = $translation;
     }
 
     if (!$return) {
       $return = $default_translation;
     }
 
     return $return;
   }
 
   public function addPHIDHeaders($name, array $phids) {
     foreach ($phids as $phid) {
       $this->addHeader($name, '<'.$phid.'>');
     }
     return $this;
   }
 
   public function addHeader($name, $value) {
     $this->parameters['headers'][] = array($name, $value);
     return $this;
   }
 
   public function addAttachment(PhabricatorMetaMTAAttachment $attachment) {
     $this->parameters['attachments'][] = $attachment->toDictionary();
     return $this;
   }
 
   public function getAttachments() {
     $dicts = $this->getParam('attachments');
 
     $result = array();
     foreach ($dicts as $dict) {
       $result[] = PhabricatorMetaMTAAttachment::newFromDictionary($dict);
     }
     return $result;
   }
 
   public function setAttachments(array $attachments) {
     assert_instances_of($attachments, 'PhabricatorMetaMTAAttachment');
     $this->setParam('attachments', mpull($attachments, 'toDictionary'));
     return $this;
   }
 
   public function setFrom($from) {
     $this->setParam('from', $from);
     return $this;
   }
 
   public function setReplyTo($reply_to) {
     $this->setParam('reply-to', $reply_to);
     return $this;
   }
 
   public function setSubject($subject) {
     $this->setParam('subject', $subject);
     return $this;
   }
 
   public function setSubjectPrefix($prefix) {
     $this->setParam('subject-prefix', $prefix);
     return $this;
   }
 
   public function setVarySubjectPrefix($prefix) {
     $this->setParam('vary-subject-prefix', $prefix);
     return $this;
   }
 
   public function setBody($body) {
     $this->setParam('body', $body);
     return $this;
   }
 
   public function getBody() {
     return $this->getParam('body');
   }
 
   public function setIsHTML($html) {
     $this->setParam('is-html', $html);
     return $this;
   }
 
   public function setIsErrorEmail($is_error) {
     $this->setParam('is-error', $is_error);
     return $this;
   }
 
   public function getIsErrorEmail() {
     return $this->getParam('is-error', false);
   }
 
   public function getWorkerTaskID() {
     return $this->getParam('worker-task');
   }
 
   public function setWorkerTaskID($id) {
     $this->setParam('worker-task', $id);
     return $this;
   }
 
   public function getToPHIDs() {
     return $this->getParam('to', array());
   }
 
   public function getRawToAddresses() {
     return $this->getParam('raw-to', array());
   }
 
   public function getCcPHIDs() {
     return $this->getParam('cc', array());
   }
 
   /**
    * Flag that this is an auto-generated bulk message and should have bulk
    * headers added to it if appropriate. Broadly, this means some flavor of
    * "Precedence: bulk" or similar, but is implementation and configuration
    * dependent.
    *
    * @param bool  True if the mail is automated bulk mail.
    * @return this
    */
   public function setIsBulk($is_bulk) {
     $this->setParam('is-bulk', $is_bulk);
     return $this;
   }
 
   /**
    * Use this method to set an ID used for message threading. MetaMTA will
    * set appropriate headers (Message-ID, In-Reply-To, References and
    * Thread-Index) based on the capabilities of the underlying mailer.
    *
    * @param string  Unique identifier, appropriate for use in a Message-ID,
    *                In-Reply-To or References headers.
    * @param bool    If true, indicates this is the first message in the thread.
    * @return this
    */
   public function setThreadID($thread_id, $is_first_message = false) {
     $this->setParam('thread-id', $thread_id);
     $this->setParam('is-first-message', $is_first_message);
     return $this;
   }
 
   /**
    * Save a newly created mail to the database. The mail will eventually be
    * delivered by the MetaMTA daemon.
    *
    * @return this
    */
   public function saveAndSend() {
     return $this->save();
   }
 
-  protected function didWriteData() {
-    parent::didWriteData();
+  public function save() {
+    if ($this->getID()) {
+      return parent::save();
+    }
+
+    // NOTE: When mail is sent from CLI scripts that run tasks in-process, we
+    // may re-enter this method from within scheduleTask(). The implementation
+    // is intended to avoid anything awkward if we end up reentering this
+    // method.
 
-    if (!$this->getWorkerTaskID()) {
+    $this->openTransaction();
+      // Save to generate a task ID.
+      parent::save();
+
+      // Queue a task to send this mail.
       $mailer_task = PhabricatorWorker::scheduleTask(
         'PhabricatorMetaMTAWorker',
         $this->getID());
 
+      // Save again to update the task ID.
       $this->setWorkerTaskID($mailer_task->getID());
-      $this->save();
-    }
-  }
+      $result = parent::save();
+    $this->saveTransaction();
 
+    return $result;
+  }
 
   public function buildDefaultMailer() {
     return PhabricatorEnv::newObjectFromConfig('metamta.mail-adapter');
   }
 
 
   /**
    * Attempt to deliver an email immediately, in this process.
    *
    * @param bool  Try to deliver this email even if it has already been
    *              delivered or is in backoff after a failed delivery attempt.
    * @param PhabricatorMailImplementationAdapter Use a specific mail adapter,
    *              instead of the default.
    *
    * @return void
    */
   public function sendNow(
     $force_send = false,
     PhabricatorMailImplementationAdapter $mailer = null) {
 
     if ($mailer === null) {
       $mailer = $this->buildDefaultMailer();
     }
 
     if (!$force_send) {
       if ($this->getStatus() != self::STATUS_QUEUE) {
         throw new Exception("Trying to send an already-sent mail!");
       }
     }
 
     try {
       $params = $this->parameters;
 
       $actors = $this->loadAllActors();
       $deliverable_actors = $this->filterDeliverableActors($actors);
 
       $default_from = PhabricatorEnv::getEnvConfig('metamta.default-address');
       if (empty($params['from'])) {
         $mailer->setFrom($default_from);
       }
 
       $is_first = idx($params, 'is-first-message');
       unset($params['is-first-message']);
 
       $is_threaded = (bool)idx($params, 'thread-id');
 
       $reply_to_name = idx($params, 'reply-to-name', '');
       unset($params['reply-to-name']);
 
       $add_cc = array();
       $add_to = array();
 
       foreach ($params as $key => $value) {
         switch ($key) {
           case 'from':
             $from = $value;
             $actor_email = null;
             $actor_name = null;
             $actor = idx($actors, $from);
             if ($actor) {
               $actor_email = $actor->getEmailAddress();
               $actor_name = $actor->getName();
             }
             $can_send_as_user = $actor_email &&
               PhabricatorEnv::getEnvConfig('metamta.can-send-as-user');
 
             if ($can_send_as_user) {
               $mailer->setFrom($actor_email, $actor_name);
             } else {
               $from_email = coalesce($actor_email, $default_from);
               $from_name = coalesce($actor_name, pht('Phabricator'));
 
               if (empty($params['reply-to'])) {
                 $params['reply-to'] = $from_email;
                 $params['reply-to-name'] = $from_name;
               }
 
               $mailer->setFrom($default_from, $from_name);
             }
             break;
           case 'reply-to':
             $mailer->addReplyTo($value, $reply_to_name);
             break;
           case 'to':
             $to_phids = $this->expandRecipients($value);
             $to_actors = array_select_keys($deliverable_actors, $to_phids);
             $add_to = array_merge(
               $add_to,
               mpull($to_actors, 'getEmailAddress'));
             break;
           case 'raw-to':
             $add_to = array_merge($add_to, $value);
             break;
           case 'cc':
             $cc_phids = $this->expandRecipients($value);
             $cc_actors = array_select_keys($deliverable_actors, $cc_phids);
             $add_cc = array_merge(
               $add_cc,
               mpull($cc_actors, 'getEmailAddress'));
             break;
           case 'headers':
             foreach ($value as $pair) {
               list($header_key, $header_value) = $pair;
 
               // NOTE: If we have \n in a header, SES rejects the email.
               $header_value = str_replace("\n", " ", $header_value);
 
               $mailer->addHeader($header_key, $header_value);
             }
             break;
           case 'attachments':
             $value = $this->getAttachments();
             foreach ($value as $attachment) {
               $mailer->addAttachment(
                 $attachment->getData(),
                 $attachment->getFilename(),
                 $attachment->getMimeType());
             }
             break;
           case 'body':
             $max = PhabricatorEnv::getEnvConfig('metamta.email-body-limit');
             if (strlen($value) > $max) {
               $value = phutil_utf8_shorten($value, $max);
               $value .= "\n";
               $value .= pht('(This email was truncated at %d bytes.)', $max);
             }
             $mailer->setBody($value);
             break;
           case 'subject':
             // Only try to use preferences if everything is multiplexed, so we
             // get consistent behavior.
             $use_prefs = self::shouldMultiplexAllMail();
 
             $prefs = null;
             if ($use_prefs) {
 
               // If multiplexing is enabled, some recipients will be in "Cc"
               // rather than "To". We'll move them to "To" later (or supply a
               // dummy "To") but need to look for the recipient in either the
               // "To" or "Cc" fields here.
               $target_phid = head(idx($params, 'to', array()));
               if (!$target_phid) {
                 $target_phid = head(idx($params, 'cc', array()));
               }
 
               if ($target_phid) {
                 $user = id(new PhabricatorUser())->loadOneWhere(
                   'phid = %s',
                   $target_phid);
                 if ($user) {
                   $prefs = $user->loadPreferences();
                 }
               }
             }
 
             $subject = array();
 
             if ($is_threaded) {
               $add_re = PhabricatorEnv::getEnvConfig('metamta.re-prefix');
 
               if ($prefs) {
                 $add_re = $prefs->getPreference(
                   PhabricatorUserPreferences::PREFERENCE_RE_PREFIX,
                   $add_re);
               }
 
               if ($add_re) {
                 $subject[] = 'Re:';
               }
             }
 
             $subject[] = trim(idx($params, 'subject-prefix'));
 
             $vary_prefix = idx($params, 'vary-subject-prefix');
             if ($vary_prefix != '') {
               $use_subject = PhabricatorEnv::getEnvConfig(
                 'metamta.vary-subjects');
 
               if ($prefs) {
                 $use_subject = $prefs->getPreference(
                   PhabricatorUserPreferences::PREFERENCE_VARY_SUBJECT,
                   $use_subject);
               }
 
               if ($use_subject) {
                 $subject[] = $vary_prefix;
               }
             }
 
             $subject[] = $value;
 
             $mailer->setSubject(implode(' ', array_filter($subject)));
             break;
           case 'is-html':
             if ($value) {
               $mailer->setIsHTML(true);
             }
             break;
           case 'is-bulk':
             if ($value) {
               if (PhabricatorEnv::getEnvConfig('metamta.precedence-bulk')) {
                 $mailer->addHeader('Precedence', 'bulk');
               }
             }
             break;
           case 'thread-id':
 
             // NOTE: Gmail freaks out about In-Reply-To and References which
             // aren't in the form "<string@domain.tld>"; this is also required
             // by RFC 2822, although some clients are more liberal in what they
             // accept.
             $domain = PhabricatorEnv::getEnvConfig('metamta.domain');
             $value = '<'.$value.'@'.$domain.'>';
 
             if ($is_first && $mailer->supportsMessageIDHeader()) {
               $mailer->addHeader('Message-ID',  $value);
             } else {
               $in_reply_to = $value;
               $references = array($value);
               $parent_id = $this->getParentMessageID();
               if ($parent_id) {
                 $in_reply_to = $parent_id;
                 // By RFC 2822, the most immediate parent should appear last
                 // in the "References" header, so this order is intentional.
                 $references[] = $parent_id;
               }
               $references = implode(' ', $references);
               $mailer->addHeader('In-Reply-To', $in_reply_to);
               $mailer->addHeader('References',  $references);
             }
             $thread_index = $this->generateThreadIndex($value, $is_first);
             $mailer->addHeader('Thread-Index', $thread_index);
             break;
           case 'mailtags':
             // Handled below.
             break;
           case 'subject-prefix':
           case 'vary-subject-prefix':
             // Handled above.
             break;
           default:
             // Just discard.
         }
       }
 
       if (!$add_to && !$add_cc) {
         $this->setStatus(self::STATUS_VOID);
         $this->setMessage(
           "Message has no valid recipients: all To/Cc are disabled, invalid, ".
           "or configured not to receive this mail.");
         return $this->save();
       }
 
       if ($this->getIsErrorEmail()) {
         $all_recipients = array_merge($add_to, $add_cc);
         if ($this->shouldRateLimitMail($all_recipients)) {
           $this->setStatus(self::STATUS_VOID);
           $this->setMessage(
             pht(
               'This is an error email, but one or more recipients have '.
               'exceeded the error email rate limit. Declining to deliver '.
               'message.'));
           return $this->save();
         }
       }
 
       $mailer->addHeader('X-Phabricator-Sent-This-Message', 'Yes');
       $mailer->addHeader('X-Mail-Transport-Agent', 'MetaMTA');
 
       // Some clients respect this to suppress OOF and other auto-responses.
       $mailer->addHeader('X-Auto-Response-Suppress', 'All');
 
       // If the message has mailtags, filter out any recipients who don't want
       // to receive this type of mail.
       $mailtags = $this->getParam('mailtags');
       if ($mailtags) {
         $tag_header = array();
         foreach ($mailtags as $mailtag) {
           $tag_header[] = '<'.$mailtag.'>';
         }
         $tag_header = implode(', ', $tag_header);
         $mailer->addHeader('X-Phabricator-Mail-Tags', $tag_header);
       }
 
       // Some mailers require a valid "To:" in order to deliver mail. If we
       // don't have any "To:", try to fill it in with a placeholder "To:".
       // If that also fails, move the "Cc:" line to "To:".
       if (!$add_to) {
         $placeholder_key = 'metamta.placeholder-to-recipient';
         $placeholder = PhabricatorEnv::getEnvConfig($placeholder_key);
         if ($placeholder !== null) {
           $add_to = array($placeholder);
         } else {
           $add_to = $add_cc;
           $add_cc = array();
         }
       }
 
       $add_to = array_unique($add_to);
       $add_cc = array_unique($add_cc);
 
       $mailer->addTos($add_to);
       if ($add_cc) {
         $mailer->addCCs($add_cc);
       }
     } catch (Exception $ex) {
       $this->setStatus(self::STATUS_FAIL);
       $this->setMessage($ex->getMessage());
       return $this->save();
     }
 
     try {
       $ok = $mailer->send();
       $error = null;
     } catch (PhabricatorMetaMTAPermanentFailureException $ex) {
       $this->setStatus(self::STATUS_FAIL);
       $this->setMessage($ex->getMessage());
       return $this->save();
     } catch (Exception $ex) {
       $ok = false;
       $error = $ex->getMessage()."\n".$ex->getTraceAsString();
     }
 
     if (!$ok) {
       $this->setMessage($error);
     } else {
       $this->setStatus(self::STATUS_SENT);
     }
 
     return $this->save();
   }
 
   public static function getReadableStatus($status_code) {
     static $readable = array(
       self::STATUS_QUEUE => "Queued for Delivery",
       self::STATUS_FAIL  => "Delivery Failed",
       self::STATUS_SENT  => "Sent",
       self::STATUS_VOID  => "Void",
     );
     $status_code = coalesce($status_code, '?');
     return idx($readable, $status_code, $status_code);
   }
 
   private function generateThreadIndex($seed, $is_first_mail) {
     // When threading, Outlook ignores the 'References' and 'In-Reply-To'
     // headers that most clients use. Instead, it uses a custom 'Thread-Index'
     // header. The format of this header is something like this (from
     // camel-exchange-folder.c in Evolution Exchange):
 
     /* A new post to a folder gets a 27-byte-long thread index. (The value
      * is apparently unique but meaningless.) Each reply to a post gets a
      * 32-byte-long thread index whose first 27 bytes are the same as the
      * parent's thread index. Each reply to any of those gets a
      * 37-byte-long thread index, etc. The Thread-Index header contains a
      * base64 representation of this value.
      */
 
     // The specific implementation uses a 27-byte header for the first email
     // a recipient receives, and a random 5-byte suffix (32 bytes total)
     // thereafter. This means that all the replies are (incorrectly) siblings,
     // but it would be very difficult to keep track of the entire tree and this
     // gets us reasonable client behavior.
 
     $base = substr(md5($seed), 0, 27);
     if (!$is_first_mail) {
       // Not totally sure, but it seems like outlook orders replies by
       // thread-index rather than timestamp, so to get these to show up in the
       // right order we use the time as the last 4 bytes.
       $base .= ' '.pack('N', time());
     }
 
     return base64_encode($base);
   }
 
   public static function shouldMultiplexAllMail() {
     return PhabricatorEnv::getEnvConfig('metamta.one-mail-per-recipient');
   }
 
 
 /* -(  Managing Recipients  )------------------------------------------------ */
 
 
   /**
    * Get all of the recipients for this mail, after preference filters are
    * applied. This list has all objects to whom delivery will be attempted.
    *
    * @return  list<phid>  A list of all recipients to whom delivery will be
    *                      attempted.
    * @task recipients
    */
   public function buildRecipientList() {
     $actors = $this->loadActors(
       array_merge(
         $this->getToPHIDs(),
         $this->getCcPHIDs()));
     $actors = $this->filterDeliverableActors($actors);
     return mpull($actors, 'getPHID');
   }
 
   public function loadAllActors() {
     $actor_phids = array_merge(
       array($this->getParam('from')),
       $this->getToPHIDs(),
       $this->getCcPHIDs());
 
     $this->loadRecipientExpansions($actor_phids);
     $actor_phids = $this->expandRecipients($actor_phids);
 
     return $this->loadActors($actor_phids);
   }
 
   private function loadRecipientExpansions(array $phids) {
     $expansions = id(new PhabricatorMetaMTAMemberQuery())
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withPHIDs($phids)
       ->execute();
 
     $this->recipientExpansionMap = $expansions;
 
     return $this;
   }
 
   /**
    * Expand a list of recipient PHIDs (possibly including aggregate recipients
    * like projects) into a deaggregated list of individual recipient PHIDs.
    * For example, this will expand project PHIDs into a list of the project's
    * members.
    *
    * @param list<phid>  List of recipient PHIDs, possibly including aggregate
    *                    recipients.
    * @return list<phid> Deaggregated list of mailable recipients.
    */
   private function expandRecipients(array $phids) {
     if ($this->recipientExpansionMap === null) {
       throw new Exception(
         pht(
           'Call loadRecipientExpansions() before expandRecipients()!'));
     }
 
     $results = array();
     foreach ($phids as $phid) {
       if (!isset($this->recipientExpansionMap[$phid])) {
         $results[$phid] = $phid;
       } else {
         foreach ($this->recipientExpansionMap[$phid] as $recipient_phid) {
           $results[$recipient_phid] = $recipient_phid;
         }
       }
     }
 
     return array_keys($results);
   }
 
   private function filterDeliverableActors(array $actors) {
     assert_instances_of($actors, 'PhabricatorMetaMTAActor');
     $deliverable_actors = array();
     foreach ($actors as $phid => $actor) {
       if ($actor->isDeliverable()) {
         $deliverable_actors[$phid] = $actor;
       }
     }
     return $deliverable_actors;
   }
 
   private function loadActors(array $actor_phids) {
     $actor_phids = array_filter($actor_phids);
     $viewer = PhabricatorUser::getOmnipotentUser();
 
     $actors = id(new PhabricatorMetaMTAActorQuery())
       ->setViewer($viewer)
       ->withPHIDs($actor_phids)
       ->execute();
 
     if (!$actors) {
       return array();
     }
 
     // Exclude explicit recipients.
     foreach ($this->getExcludeMailRecipientPHIDs() as $phid) {
       $actor = idx($actors, $phid);
       if (!$actor) {
         continue;
       }
       $actor->setUndeliverable(
         pht(
           'This message is a response to another email message, and this '.
           'recipient received the original email message, so we are not '.
           'sending them this substantially similar message (for example, '.
           'the sender used "Reply All" instead of "Reply" in response to '.
           'mail from Phabricator).'));
     }
 
     // Exclude the actor if their preferences are set.
     $from_phid = $this->getParam('from');
     $from_actor = idx($actors, $from_phid);
     if ($from_actor) {
       $from_user = id(new PhabricatorPeopleQuery())
         ->setViewer($viewer)
         ->withPHIDs(array($from_phid))
         ->execute();
       $from_user = head($from_user);
       if ($from_user && !$this->getOverrideNoSelfMailPreference()) {
         $pref_key = PhabricatorUserPreferences::PREFERENCE_NO_SELF_MAIL;
         $exclude_self = $from_user
           ->loadPreferences()
           ->getPreference($pref_key);
         if ($exclude_self) {
           $from_actor->setUndeliverable(
             pht(
               'This recipient is the user whose actions caused delivery of '.
               'this message, but they have set preferences so they do not '.
               'receive mail about their own actions (Settings > Email '.
               'Preferences > Self Actions).'));
         }
       }
     }
 
 
     // Exclude all recipients who have set preferences to not receive this type
     // of email (for example, a user who says they don't want emails about task
     // CC changes).
     $tags = $this->getParam('mailtags');
     if ($tags) {
       $all_prefs = id(new PhabricatorUserPreferences())->loadAllWhere(
         'userPHID in (%Ls)',
         $actor_phids);
       $all_prefs = mpull($all_prefs, null, 'getUserPHID');
 
       foreach ($all_prefs as $phid => $prefs) {
         $user_mailtags = $prefs->getPreference(
           PhabricatorUserPreferences::PREFERENCE_MAILTAGS,
           array());
 
         // The user must have elected to receive mail for at least one
         // of the mailtags.
         $send = false;
         foreach ($tags as $tag) {
           if (idx($user_mailtags, $tag, true)) {
             $send = true;
             break;
           }
         }
 
         if (!$send) {
           $actors[$phid]->setUndeliverable(
             pht(
               'This mail has tags which control which users receive it, and '.
               'this recipient has not elected to receive mail with any of '.
               'the tags on this message (Settings > Email Preferences).'));
         }
       }
     }
 
     return $actors;
   }
 
   private function shouldRateLimitMail(array $all_recipients) {
     try {
       PhabricatorSystemActionEngine::willTakeAction(
         $all_recipients,
         new PhabricatorMetaMTAErrorMailAction(),
         1);
       return false;
     } catch (PhabricatorSystemActionRateLimitException $ex) {
       return true;
     }
   }
 
 
 }
diff --git a/src/applications/transactions/constants/PhabricatorTransactions.php b/src/applications/transactions/constants/PhabricatorTransactions.php
index 1f86f3cd29..eb4b84723e 100644
--- a/src/applications/transactions/constants/PhabricatorTransactions.php
+++ b/src/applications/transactions/constants/PhabricatorTransactions.php
@@ -1,24 +1,25 @@
 <?php
 
 final class PhabricatorTransactions {
 
   const TYPE_COMMENT      = 'core:comment';
   const TYPE_SUBSCRIBERS  = 'core:subscribers';
   const TYPE_VIEW_POLICY  = 'core:view-policy';
   const TYPE_EDIT_POLICY  = 'core:edit-policy';
   const TYPE_JOIN_POLICY  = 'core:join-policy';
   const TYPE_EDGE         = 'core:edge';
   const TYPE_CUSTOMFIELD  = 'core:customfield';
+  const TYPE_BUILDABLE    = 'harbormaster:buildable';
 
   const COLOR_RED         = 'red';
   const COLOR_ORANGE      = 'orange';
   const COLOR_YELLOW      = 'yellow';
   const COLOR_GREEN       = 'green';
   const COLOR_SKY         = 'sky';
   const COLOR_BLUE        = 'blue';
   const COLOR_INDIGO      = 'indigo';
   const COLOR_VIOLET      = 'violet';
   const COLOR_GREY        = 'grey';
   const COLOR_BLACK       = 'black';
 
 }
diff --git a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
index 7208f87d45..dc033b6e35 100644
--- a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
+++ b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
@@ -1,2203 +1,2213 @@
 <?php
 
 /**
  * @task mail   Sending Mail
  * @task feed   Publishing Feed Stories
  * @task search Search Index
  * @task files  Integration with Files
  */
 abstract class PhabricatorApplicationTransactionEditor
   extends PhabricatorEditor {
 
   private $contentSource;
   private $object;
   private $xactions;
 
   private $isNewObject;
   private $mentionedPHIDs;
   private $continueOnNoEffect;
   private $continueOnMissingFields;
   private $parentMessageID;
   private $heraldAdapter;
   private $heraldTranscript;
   private $subscribers;
 
   private $isPreview;
   private $isHeraldEditor;
   private $actingAsPHID;
   private $disableEmail;
 
   public function setActingAsPHID($acting_as_phid) {
     $this->actingAsPHID = $acting_as_phid;
     return $this;
   }
 
   public function getActingAsPHID() {
     if ($this->actingAsPHID) {
       return $this->actingAsPHID;
     }
     return $this->getActor()->getPHID();
   }
 
   /**
    * When the editor tries to apply transactions that have no effect, should
    * it raise an exception (default) or drop them and continue?
    *
    * Generally, you will set this flag for edits coming from "Edit" interfaces,
    * and leave it cleared for edits coming from "Comment" interfaces, so the
    * user will get a useful error if they try to submit a comment that does
    * nothing (e.g., empty comment with a status change that has already been
    * performed by another user).
    *
    * @param bool  True to drop transactions without effect and continue.
    * @return this
    */
   public function setContinueOnNoEffect($continue) {
     $this->continueOnNoEffect = $continue;
     return $this;
   }
 
   public function getContinueOnNoEffect() {
     return $this->continueOnNoEffect;
   }
 
 
   /**
    * When the editor tries to apply transactions which don't populate all of
    * an object's required fields, should it raise an exception (default) or
    * drop them and continue?
    *
    * For example, if a user adds a new required custom field (like "Severity")
    * to a task, all existing tasks won't have it populated. When users
    * manually edit existing tasks, it's usually desirable to have them provide
    * a severity. However, other operations (like batch editing just the
    * owner of a task) will fail by default.
    *
    * By setting this flag for edit operations which apply to specific fields
    * (like the priority, batch, and merge editors in Maniphest), these
    * operations can continue to function even if an object is outdated.
    *
    * @param bool  True to continue when transactions don't completely satisfy
    *              all required fields.
    * @return this
    */
   public function setContinueOnMissingFields($continue_on_missing_fields) {
     $this->continueOnMissingFields = $continue_on_missing_fields;
     return $this;
   }
 
   public function getContinueOnMissingFields() {
     return $this->continueOnMissingFields;
   }
 
 
   /**
    * Not strictly necessary, but reply handlers ideally set this value to
    * make email threading work better.
    */
   public function setParentMessageID($parent_message_id) {
     $this->parentMessageID = $parent_message_id;
     return $this;
   }
   public function getParentMessageID() {
     return $this->parentMessageID;
   }
 
   public function getIsNewObject() {
     return $this->isNewObject;
   }
 
   protected function getMentionedPHIDs() {
     return $this->mentionedPHIDs;
   }
 
   public function setIsPreview($is_preview) {
     $this->isPreview = $is_preview;
     return $this;
   }
 
   public function getIsPreview() {
     return $this->isPreview;
   }
 
   public function setIsHeraldEditor($is_herald_editor) {
     $this->isHeraldEditor = $is_herald_editor;
     return $this;
   }
 
   public function getIsHeraldEditor() {
     return $this->isHeraldEditor;
   }
 
   /**
    * Prevent this editor from generating email when applying transactions.
    *
    * @param bool  True to disable email.
    * @return this
    */
   public function setDisableEmail($disable_email) {
     $this->disableEmail = $disable_email;
     return $this;
   }
 
   public function getDisableEmail() {
     return $this->disableEmail;
   }
 
   public function getTransactionTypes() {
     $types = array();
 
     if ($this->object instanceof PhabricatorSubscribableInterface) {
       $types[] = PhabricatorTransactions::TYPE_SUBSCRIBERS;
     }
 
     if ($this->object instanceof PhabricatorCustomFieldInterface) {
       $types[] = PhabricatorTransactions::TYPE_CUSTOMFIELD;
     }
 
+    if ($this->object instanceof HarbormasterBuildableInterface) {
+      $types[] = PhabricatorTransactions::TYPE_BUILDABLE;
+    }
+
     return $types;
   }
 
   private function adjustTransactionValues(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     if ($xaction->shouldGenerateOldValue()) {
       $old = $this->getTransactionOldValue($object, $xaction);
       $xaction->setOldValue($old);
     }
 
     $new = $this->getTransactionNewValue($object, $xaction);
     $xaction->setNewValue($new);
   }
 
   private function getTransactionOldValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return array_values($this->subscribers);
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         return $object->getViewPolicy();
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         return $object->getEditPolicy();
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return $object->getJoinPolicy();
       case PhabricatorTransactions::TYPE_EDGE:
         $edge_type = $xaction->getMetadataValue('edge:type');
         if (!$edge_type) {
           throw new Exception("Edge transaction has no 'edge:type'!");
         }
 
         $old_edges = array();
         if ($object->getPHID()) {
           $edge_src = $object->getPHID();
 
           $old_edges = id(new PhabricatorEdgeQuery())
             ->withSourcePHIDs(array($edge_src))
             ->withEdgeTypes(array($edge_type))
             ->needEdgeData(true)
             ->execute();
 
           $old_edges = $old_edges[$edge_src][$edge_type];
         }
         return $old_edges;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         // NOTE: Custom fields have their old value pre-populated when they are
         // built by PhabricatorCustomFieldList.
         return $xaction->getOldValue();
       case PhabricatorTransactions::TYPE_COMMENT:
         return null;
       default:
         return $this->getCustomTransactionOldValue($object, $xaction);
     }
   }
 
   private function getTransactionNewValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return $this->getPHIDTransactionNewValue($xaction);
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
+      case PhabricatorTransactions::TYPE_BUILDABLE:
         return $xaction->getNewValue();
       case PhabricatorTransactions::TYPE_EDGE:
         return $this->getEdgeTransactionNewValue($xaction);
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->getNewValueFromApplicationTransactions($xaction);
       case PhabricatorTransactions::TYPE_COMMENT:
         return null;
       default:
         return $this->getCustomTransactionNewValue($object, $xaction);
     }
   }
 
   protected function getCustomTransactionOldValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     throw new Exception("Capability not supported!");
   }
 
   protected function getCustomTransactionNewValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     throw new Exception("Capability not supported!");
   }
 
   protected function transactionHasEffect(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return $xaction->hasComment();
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->getApplicationTransactionHasEffect($xaction);
       case PhabricatorTransactions::TYPE_EDGE:
         // A straight value comparison here doesn't always get the right
         // result, because newly added edges aren't fully populated. Instead,
         // compare the changes in a more granular way.
         $old = $xaction->getOldValue();
         $new = $xaction->getNewValue();
 
         $old_dst = array_keys($old);
         $new_dst = array_keys($new);
 
         // NOTE: For now, we don't consider edge reordering to be a change.
         // We have very few order-dependent edges and effectively no order
         // oriented UI. This might change in the future.
         sort($old_dst);
         sort($new_dst);
 
         if ($old_dst !== $new_dst) {
           // We've added or removed edges, so this transaction definitely
           // has an effect.
           return true;
         }
 
         // We haven't added or removed edges, but we might have changed
         // edge data.
         foreach ($old as $key => $old_value) {
           $new_value = $new[$key];
           if ($old_value['data'] !== $new_value['data']) {
             return true;
           }
         }
 
         return false;
     }
 
     return ($xaction->getOldValue() !== $xaction->getNewValue());
   }
 
   protected function shouldApplyInitialEffects(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return false;
   }
 
   protected function applyInitialEffects(
     PhabricatorLiskDAO $object,
     array $xactions) {
     throw new Exception('Not implemented.');
   }
 
   private function applyInternalEffects(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        return;
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         $object->setViewPolicy($xaction->getNewValue());
         break;
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         $object->setEditPolicy($xaction->getNewValue());
         break;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->applyApplicationTransactionInternalEffects($xaction);
     }
+
     return $this->applyCustomInternalTransaction($object, $xaction);
   }
 
   private function applyExternalEffects(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     switch ($xaction->getTransactionType()) {
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        return;
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $subeditor = id(new PhabricatorSubscriptionsEditor())
           ->setObject($object)
           ->setActor($this->requireActor());
 
         $old_map = array_fuse($xaction->getOldValue());
         $new_map = array_fuse($xaction->getNewValue());
 
         $subeditor->unsubscribe(
           array_keys(
             array_diff_key($old_map, $new_map)));
 
         $subeditor->subscribeExplicit(
           array_keys(
             array_diff_key($new_map, $old_map)));
 
         $subeditor->save();
 
         // for the rest of these edits, subscribers should include those just
         // added as well as those just removed.
         $subscribers = array_unique(array_merge(
           $this->subscribers,
           $xaction->getOldValue(),
           $xaction->getNewValue()));
         $this->subscribers = $subscribers;
 
         break;
       case PhabricatorTransactions::TYPE_EDGE:
         $old = $xaction->getOldValue();
         $new = $xaction->getNewValue();
         $src = $object->getPHID();
         $type = $xaction->getMetadataValue('edge:type');
 
         foreach ($new as $dst_phid => $edge) {
           $new[$dst_phid]['src'] = $src;
         }
 
         $editor = id(new PhabricatorEdgeEditor())
           ->setActor($this->getActor());
 
         foreach ($old as $dst_phid => $edge) {
           if (!empty($new[$dst_phid])) {
             if ($old[$dst_phid]['data'] === $new[$dst_phid]['data']) {
               continue;
             }
           }
           $editor->removeEdge($src, $type, $dst_phid);
         }
 
         foreach ($new as $dst_phid => $edge) {
           if (!empty($old[$dst_phid])) {
             if ($old[$dst_phid]['data'] === $new[$dst_phid]['data']) {
               continue;
             }
           }
 
           $data = array(
             'data' => $edge['data'],
           );
 
           $editor->addEdge($src, $type, $dst_phid, $data);
         }
 
         $editor->save();
         break;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->applyApplicationTransactionExternalEffects($xaction);
     }
 
     return $this->applyCustomExternalTransaction($object, $xaction);
   }
 
   protected function applyCustomInternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     $type = $xaction->getTransactionType();
     throw new Exception(
       "Transaction type '{$type}' is missing an internal apply ".
       "implementation!");
   }
 
   protected function applyCustomExternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     $type = $xaction->getTransactionType();
     throw new Exception(
       "Transaction type '{$type}' is missing an external apply ".
       "implementation!");
   }
 
   /**
    * Fill in a transaction's common values, like author and content source.
    */
   protected function populateTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     $actor = $this->getActor();
 
     // TODO: This needs to be more sophisticated once we have meta-policies.
     $xaction->setViewPolicy(PhabricatorPolicies::POLICY_PUBLIC);
 
     if ($actor->isOmnipotent()) {
       $xaction->setEditPolicy(PhabricatorPolicies::POLICY_NOONE);
     } else {
       $xaction->setEditPolicy($actor->getPHID());
     }
 
     $xaction->setAuthorPHID($this->getActingAsPHID());
     $xaction->setContentSource($this->getContentSource());
     $xaction->attachViewer($actor);
     $xaction->attachObject($object);
 
     if ($object->getPHID()) {
       $xaction->setObjectPHID($object->getPHID());
     }
 
     return $xaction;
   }
 
 
   protected function applyFinalEffects(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return $xactions;
   }
 
   public function setContentSource(PhabricatorContentSource $content_source) {
     $this->contentSource = $content_source;
     return $this;
   }
 
   public function setContentSourceFromRequest(AphrontRequest $request) {
     return $this->setContentSource(
       PhabricatorContentSource::newFromRequest($request));
   }
 
   public function setContentSourceFromConduitRequest(
     ConduitAPIRequest $request) {
 
     $content_source = PhabricatorContentSource::newForSource(
       PhabricatorContentSource::SOURCE_CONDUIT,
       array());
 
     return $this->setContentSource($content_source);
   }
 
   public function getContentSource() {
     return $this->contentSource;
   }
 
   final public function applyTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $this->object = $object;
     $this->xactions = $xactions;
     $this->isNewObject = ($object->getPHID() === null);
 
     $this->validateEditParameters($object, $xactions);
 
     $actor = $this->requireActor();
 
     // NOTE: Some transaction expansion requires that the edited object be
     // attached.
     foreach ($xactions as $xaction) {
       $xaction->attachObject($object);
       $xaction->attachViewer($actor);
     }
 
     $xactions = $this->expandTransactions($object, $xactions);
     $xactions = $this->expandSupportTransactions($object, $xactions);
     $xactions = $this->combineTransactions($xactions);
 
     foreach ($xactions as $xaction) {
       $xaction = $this->populateTransaction($object, $xaction);
     }
 
     $is_preview = $this->getIsPreview();
     $read_locking = false;
     $transaction_open = false;
 
     if (!$is_preview) {
       $errors = array();
       $type_map = mgroup($xactions, 'getTransactionType');
       foreach ($this->getTransactionTypes() as $type) {
         $type_xactions = idx($type_map, $type, array());
         $errors[] = $this->validateTransaction($object, $type, $type_xactions);
       }
 
       $errors = array_mergev($errors);
 
       $continue_on_missing = $this->getContinueOnMissingFields();
       foreach ($errors as $key => $error) {
         if ($continue_on_missing && $error->getIsMissingFieldError()) {
           unset($errors[$key]);
         }
       }
 
       if ($errors) {
         throw new PhabricatorApplicationTransactionValidationException($errors);
       }
 
       $file_phids = $this->extractFilePHIDs($object, $xactions);
 
       if ($object->getID()) {
         foreach ($xactions as $xaction) {
 
           // If any of the transactions require a read lock, hold one and
           // reload the object. We need to do this fairly early so that the
           // call to `adjustTransactionValues()` (which populates old values)
           // is based on the synchronized state of the object, which may differ
           // from the state when it was originally loaded.
 
           if ($this->shouldReadLock($object, $xaction)) {
             $object->openTransaction();
             $object->beginReadLocking();
             $transaction_open = true;
             $read_locking = true;
             $object->reload();
             break;
           }
         }
       }
 
       if ($this->shouldApplyInitialEffects($object, $xactions)) {
         if (!$transaction_open) {
           $object->openTransaction();
           $transaction_open = true;
         }
       }
     }
 
     if ($this->shouldApplyInitialEffects($object, $xactions)) {
       $this->applyInitialEffects($object, $xactions);
     }
 
     foreach ($xactions as $xaction) {
       $this->adjustTransactionValues($object, $xaction);
     }
 
     $xactions = $this->filterTransactions($object, $xactions);
 
     if (!$xactions) {
       if ($read_locking) {
         $object->endReadLocking();
         $read_locking = false;
       }
       if ($transaction_open) {
         $object->killTransaction();
         $transaction_open = false;
       }
       return array();
     }
 
     // Now that we've merged, filtered, and combined transactions, check for
     // required capabilities.
     foreach ($xactions as $xaction) {
       $this->requireCapabilities($object, $xaction);
     }
 
     $xactions = $this->sortTransactions($xactions);
 
     if ($is_preview) {
       $this->loadHandles($xactions);
       return $xactions;
     }
 
     $comment_editor = id(new PhabricatorApplicationTransactionCommentEditor())
       ->setActor($actor)
       ->setContentSource($this->getContentSource());
 
     if (!$transaction_open) {
       $object->openTransaction();
     }
 
       foreach ($xactions as $xaction) {
         $this->applyInternalEffects($object, $xaction);
       }
 
       $object->save();
 
       foreach ($xactions as $xaction) {
         $xaction->setObjectPHID($object->getPHID());
         if ($xaction->getComment()) {
           $xaction->setPHID($xaction->generatePHID());
           $comment_editor->applyEdit($xaction, $xaction->getComment());
         } else {
           $xaction->save();
         }
       }
 
       if ($file_phids) {
         $this->attachFiles($object, $file_phids);
       }
 
       foreach ($xactions as $xaction) {
         $this->applyExternalEffects($object, $xaction);
       }
 
       $xactions = $this->applyFinalEffects($object, $xactions);
 
       if ($read_locking) {
         $object->endReadLocking();
         $read_locking = false;
       }
 
     $object->saveTransaction();
 
     // Now that we've completely applied the core transaction set, try to apply
     // Herald rules. Herald rules are allowed to either take direct actions on
     // the database (like writing flags), or take indirect actions (like saving
     // some targets for CC when we generate mail a little later), or return
     // transactions which we'll apply normally using another Editor.
 
     // First, check if *this* is a sub-editor which is itself applying Herald
     // rules: if it is, stop working and return so we don't descend into
     // madness.
 
     // Otherwise, we're not a Herald editor, so process Herald rules (possibly
     // using a Herald editor to apply resulting transactions) and then send out
     // mail, notifications, and feed updates about everything.
 
     if ($this->getIsHeraldEditor()) {
       // We are the Herald editor, so stop work here and return the updated
       // transactions.
       return $xactions;
     } else if ($this->shouldApplyHeraldRules($object, $xactions)) {
       // We are not the Herald editor, so try to apply Herald rules.
       $herald_xactions = $this->applyHeraldRules($object, $xactions);
 
       if ($herald_xactions) {
         $xscript_id = $this->getHeraldTranscript()->getID();
         foreach ($herald_xactions as $herald_xaction) {
           $herald_xaction->setMetadataValue('herald:transcriptID', $xscript_id);
         }
 
         // NOTE: We're acting as the omnipotent user because rules deal with
         // their own policy issues. We use a synthetic author PHID (the
         // Herald application) as the author of record, so that transactions
         // will render in a reasonable way ("Herald assigned this task ...").
         $herald_actor = PhabricatorUser::getOmnipotentUser();
         $herald_phid = id(new PhabricatorApplicationHerald())->getPHID();
 
         // TODO: It would be nice to give transactions a more specific source
         // which points at the rule which generated them. You can figure this
         // out from transcripts, but it would be cleaner if you didn't have to.
 
         $herald_source = PhabricatorContentSource::newForSource(
           PhabricatorContentSource::SOURCE_HERALD,
           array());
 
         $herald_editor = newv(get_class($this), array())
           ->setContinueOnNoEffect(true)
           ->setContinueOnMissingFields(true)
           ->setParentMessageID($this->getParentMessageID())
           ->setIsHeraldEditor(true)
           ->setActor($herald_actor)
           ->setActingAsPHID($herald_phid)
           ->setContentSource($herald_source);
 
         $herald_xactions = $herald_editor->applyTransactions(
           $object,
           $herald_xactions);
 
         // Merge the new transactions into the transaction list: we want to
         // send email and publish feed stories about them, too.
         $xactions = array_merge($xactions, $herald_xactions);
       }
     }
 
     // Before sending mail or publishing feed stories, reload the object
     // subscribers to pick up changes caused by Herald (or by other side effects
     // in various transaction phases).
     $this->loadSubscribers($object);
 
     $this->loadHandles($xactions);
 
     $mail = null;
     if (!$this->getDisableEmail()) {
       if ($this->shouldSendMail($object, $xactions)) {
         $mail = $this->sendMail($object, $xactions);
       }
     }
 
     if ($this->supportsSearch()) {
       id(new PhabricatorSearchIndexer())
         ->queueDocumentForIndexing($object->getPHID());
     }
 
     if ($this->shouldPublishFeedStory($object, $xactions)) {
       $mailed = array();
       if ($mail) {
         $mailed = $mail->buildRecipientList();
       }
       $this->publishFeedStory(
         $object,
         $xactions,
         $mailed);
     }
 
     $this->didApplyTransactions($xactions);
 
     if ($object instanceof PhabricatorCustomFieldInterface) {
       // Maybe this makes more sense to move into the search index itself? For
       // now I'm putting it here since I think we might end up with things that
       // need it to be up to date once the next page loads, but if we don't go
       // there we we could move it into search once search moves to the daemons.
 
       // It now happens in the search indexer as well, but the search indexer is
       // always daemonized, so the logic above still potentially holds. We could
       // possibly get rid of this. The major motivation for putting it in the
       // indexer was to enable reindexing to work.
 
       $fields = PhabricatorCustomField::getObjectFields(
         $object,
         PhabricatorCustomField::ROLE_APPLICATIONSEARCH);
       $fields->readFieldsFromStorage($object);
       $fields->rebuildIndexes($object);
     }
 
     return $xactions;
   }
 
   protected function didApplyTransactions(array $xactions) {
     // Hook for subclasses.
     return;
   }
 
 
   /**
    * Determine if the editor should hold a read lock on the object while
    * applying a transaction.
    *
    * If the editor does not hold a lock, two editors may read an object at the
    * same time, then apply their changes without any synchronization. For most
    * transactions, this does not matter much. However, it is important for some
    * transactions. For example, if an object has a transaction count on it, both
    * editors may read the object with `count = 23`, then independently update it
    * and save the object with `count = 24` twice. This will produce the wrong
    * state: the object really has 25 transactions, but the count is only 24.
    *
    * Generally, transactions fall into one of four buckets:
    *
    *   - Append operations: Actions like adding a comment to an object purely
    *     add information to its state, and do not depend on the current object
    *     state in any way. These transactions never need to hold locks.
    *   - Overwrite operations: Actions like changing the title or description
    *     of an object replace the current value with a new value, so the end
    *     state is consistent without a lock. We currently do not lock these
    *     transactions, although we may in the future.
    *   - Edge operations: Edge and subscription operations have internal
    *     synchronization which limits the damage race conditions can cause.
    *     We do not currently lock these transactions, although we may in the
    *     future.
    *   - Update operations: Actions like incrementing a count on an object.
    *     These operations generally should use locks, unless it is not
    *     important that the state remain consistent in the presence of races.
    *
    * @param   PhabricatorLiskDAO  Object being updated.
    * @param   PhabricatorApplicationTransaction Transaction being applied.
    * @return  bool                True to synchronize the edit with a lock.
    */
   protected function shouldReadLock(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     return false;
   }
 
   private function loadHandles(array $xactions) {
     $phids = array();
     foreach ($xactions as $key => $xaction) {
       $phids[$key] = $xaction->getRequiredHandlePHIDs();
     }
     $handles = array();
     $merged = array_mergev($phids);
     if ($merged) {
       $handles = id(new PhabricatorHandleQuery())
         ->setViewer($this->requireActor())
         ->withPHIDs($merged)
         ->execute();
     }
     foreach ($xactions as $key => $xaction) {
       $xaction->setHandles(array_select_keys($handles, $phids[$key]));
     }
   }
 
   private function loadSubscribers(PhabricatorLiskDAO $object) {
     if ($object->getPHID() &&
         ($object instanceof PhabricatorSubscribableInterface)) {
       $subs = PhabricatorSubscribersQuery::loadSubscribersForPHID(
         $object->getPHID());
       $this->subscribers = array_fuse($subs);
     } else {
       $this->subscribers = array();
     }
   }
 
   private function validateEditParameters(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     if (!$this->getContentSource()) {
       throw new Exception(
         "Call setContentSource() before applyTransactions()!");
     }
 
     // Do a bunch of sanity checks that the incoming transactions are fresh.
     // They should be unsaved and have only "transactionType" and "newValue"
     // set.
 
     $types = array_fill_keys($this->getTransactionTypes(), true);
 
     assert_instances_of($xactions, 'PhabricatorApplicationTransaction');
     foreach ($xactions as $xaction) {
       if ($xaction->getPHID() || $xaction->getID()) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             "You can not apply transactions which already have IDs/PHIDs!"));
       }
       if ($xaction->getObjectPHID()) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             "You can not apply transactions which already have objectPHIDs!"));
       }
       if ($xaction->getAuthorPHID()) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             'You can not apply transactions which already have authorPHIDs!'));
       }
       if ($xaction->getCommentPHID()) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             'You can not apply transactions which already have '.
             'commentPHIDs!'));
       }
       if ($xaction->getCommentVersion() !== 0) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             'You can not apply transactions which already have '.
             'commentVersions!'));
       }
 
       $expect_value = !$xaction->shouldGenerateOldValue();
       $has_value = $xaction->hasOldValue();
 
       if ($expect_value && !$has_value) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             'This transaction is supposed to have an oldValue set, but '.
             'it does not!'));
       }
 
       if ($has_value && !$expect_value) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             'This transaction should generate its oldValue automatically, '.
             'but has already had one set!'));
       }
 
       $type = $xaction->getTransactionType();
       if (empty($types[$type])) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             'Transaction has type "%s", but that transaction type is not '.
             'supported by this editor (%s).',
             $type,
             get_class($this)));
       }
     }
   }
 
   protected function requireCapabilities(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     if ($this->getIsNewObject()) {
       return;
     }
 
     $actor = $this->requireActor();
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         PhabricatorPolicyFilter::requireCapability(
           $actor,
           $object,
           PhabricatorPolicyCapability::CAN_VIEW);
         break;
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         PhabricatorPolicyFilter::requireCapability(
           $actor,
           $object,
           PhabricatorPolicyCapability::CAN_EDIT);
         break;
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         PhabricatorPolicyFilter::requireCapability(
           $actor,
           $object,
           PhabricatorPolicyCapability::CAN_EDIT);
         break;
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         PhabricatorPolicyFilter::requireCapability(
           $actor,
           $object,
           PhabricatorPolicyCapability::CAN_EDIT);
         break;
     }
   }
 
   private function buildMentionTransaction(
     PhabricatorLiskDAO $object,
     array $xactions,
     array $blocks) {
 
     if (!($object instanceof PhabricatorSubscribableInterface)) {
       return null;
     }
 
     $texts = array_mergev($blocks);
     $phids = PhabricatorMarkupEngine::extractPHIDsFromMentions($texts);
 
     $this->mentionedPHIDs = $phids;
 
     if ($object->getPHID()) {
       // Don't try to subscribe already-subscribed mentions: we want to generate
       // a dialog about an action having no effect if the user explicitly adds
       // existing CCs, but not if they merely mention existing subscribers.
       $phids = array_diff($phids, $this->subscribers);
     }
 
     foreach ($phids as $key => $phid) {
       if ($object->isAutomaticallySubscribed($phid)) {
         unset($phids[$key]);
       }
     }
     $phids = array_values($phids);
 
     if (!$phids) {
       return null;
     }
 
     $xaction = newv(get_class(head($xactions)), array());
     $xaction->setTransactionType(PhabricatorTransactions::TYPE_SUBSCRIBERS);
     $xaction->setNewValue(array('+' => $phids));
 
     return $xaction;
   }
 
   protected function getRemarkupBlocksFromTransaction(
     PhabricatorApplicationTransaction $transaction) {
     return $transaction->getRemarkupBlocks();
   }
 
   protected function mergeTransactions(
     PhabricatorApplicationTransaction $u,
     PhabricatorApplicationTransaction $v) {
 
     $type = $u->getTransactionType();
 
     switch ($type) {
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return $this->mergePHIDOrEdgeTransactions($u, $v);
       case PhabricatorTransactions::TYPE_EDGE:
         $u_type = $u->getMetadataValue('edge:type');
         $v_type = $v->getMetadataValue('edge:type');
         if ($u_type == $v_type) {
           return $this->mergePHIDOrEdgeTransactions($u, $v);
         }
         return null;
     }
 
     // By default, do not merge the transactions.
     return null;
   }
 
   /**
    * Optionally expand transactions which imply other effects. For example,
    * resigning from a revision in Differential implies removing yourself as
    * a reviewer.
    */
   private function expandTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $results = array();
     foreach ($xactions as $xaction) {
       foreach ($this->expandTransaction($object, $xaction) as $expanded) {
         $results[] = $expanded;
       }
     }
 
     return $results;
   }
 
   protected function expandTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     return array($xaction);
   }
 
 
   private function expandSupportTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
     $this->loadSubscribers($object);
 
     $xactions = $this->applyImplicitCC($object, $xactions);
 
     $blocks = array();
     foreach ($xactions as $key => $xaction) {
       $blocks[$key] = $this->getRemarkupBlocksFromTransaction($xaction);
     }
 
     $mention_xaction = $this->buildMentionTransaction(
       $object,
       $xactions,
       $blocks);
     if ($mention_xaction) {
       $xactions[] = $mention_xaction;
     }
 
     // TODO: For now, this is just a placeholder.
     $engine = PhabricatorMarkupEngine::getEngine('extract');
 
     $block_xactions = $this->expandRemarkupBlockTransactions(
       $object,
       $xactions,
       $blocks,
       $engine);
 
     foreach ($block_xactions as $xaction) {
       $xactions[] = $xaction;
     }
 
     return $xactions;
   }
 
   private function expandRemarkupBlockTransactions(
     PhabricatorLiskDAO $object,
     array $xactions,
     $blocks,
     PhutilMarkupEngine $engine) {
     return $this->expandCustomRemarkupBlockTransactions(
       $object,
       $xactions,
       $blocks,
       $engine);
   }
 
   protected function expandCustomRemarkupBlockTransactions(
     PhabricatorLiskDAO $object,
     array $xactions,
     $blocks,
     PhutilMarkupEngine $engine) {
     return array();
   }
 
 
   /**
    * Attempt to combine similar transactions into a smaller number of total
    * transactions. For example, two transactions which edit the title of an
    * object can be merged into a single edit.
    */
   private function combineTransactions(array $xactions) {
     $stray_comments = array();
 
     $result = array();
     $types = array();
     foreach ($xactions as $key => $xaction) {
       $type = $xaction->getTransactionType();
       if (isset($types[$type])) {
         foreach ($types[$type] as $other_key) {
           $merged = $this->mergeTransactions($result[$other_key], $xaction);
           if ($merged) {
             $result[$other_key] = $merged;
 
             if ($xaction->getComment() &&
                 ($xaction->getComment() !== $merged->getComment())) {
               $stray_comments[] = $xaction->getComment();
             }
 
             if ($result[$other_key]->getComment() &&
                 ($result[$other_key]->getComment() !== $merged->getComment())) {
               $stray_comments[] = $result[$other_key]->getComment();
             }
 
             // Move on to the next transaction.
             continue 2;
           }
         }
       }
       $result[$key] = $xaction;
       $types[$type][] = $key;
     }
 
     // If we merged any comments away, restore them.
     foreach ($stray_comments as $comment) {
       $xaction = newv(get_class(head($result)), array());
       $xaction->setTransactionType(PhabricatorTransactions::TYPE_COMMENT);
       $xaction->setComment($comment);
       $result[] = $xaction;
     }
 
     return array_values($result);
   }
 
   protected function mergePHIDOrEdgeTransactions(
     PhabricatorApplicationTransaction $u,
     PhabricatorApplicationTransaction $v) {
 
     $result = $u->getNewValue();
     foreach ($v->getNewValue() as $key => $value) {
       if ($u->getTransactionType() == PhabricatorTransactions::TYPE_EDGE) {
         if (empty($result[$key])) {
           $result[$key] = $value;
         } else {
           // We're merging two lists of edge adds, sets, or removes. Merge
           // them by merging individual PHIDs within them.
           $merged = $result[$key];
 
           foreach ($value as $dst => $v_spec) {
             if (empty($merged[$dst])) {
               $merged[$dst] = $v_spec;
             } else {
               // Two transactions are trying to perform the same operation on
               // the same edge. Normalize the edge data and then merge it. This
               // allows transactions to specify how data merges execute in a
               // precise way.
 
               $u_spec = $merged[$dst];
 
               if (!is_array($u_spec)) {
                 $u_spec = array('dst' => $u_spec);
               }
               if (!is_array($v_spec)) {
                 $v_spec = array('dst' => $v_spec);
               }
 
               $ux_data = idx($u_spec, 'data', array());
               $vx_data = idx($v_spec, 'data', array());
 
               $merged_data = $this->mergeEdgeData(
                 $u->getMetadataValue('edge:type'),
                 $ux_data,
                 $vx_data);
 
               $u_spec['data'] = $merged_data;
               $merged[$dst] = $u_spec;
             }
           }
 
           $result[$key] = $merged;
         }
       } else {
         $result[$key] = array_merge($value, idx($result, $key, array()));
       }
     }
     $u->setNewValue($result);
 
     // When combining an "ignore" transaction with a normal transaction, make
     // sure we don't propagate the "ignore" flag.
     if (!$v->getIgnoreOnNoEffect()) {
       $u->setIgnoreOnNoEffect(false);
     }
 
     return $u;
   }
 
   protected function mergeEdgeData($type, array $u, array $v) {
     return $v + $u;
   }
 
   protected function getPHIDTransactionNewValue(
     PhabricatorApplicationTransaction $xaction) {
 
     $old = array_fuse($xaction->getOldValue());
 
     $new = $xaction->getNewValue();
     $new_add = idx($new, '+', array());
     unset($new['+']);
     $new_rem = idx($new, '-', array());
     unset($new['-']);
     $new_set = idx($new, '=', null);
     if ($new_set !== null) {
       $new_set = array_fuse($new_set);
     }
     unset($new['=']);
 
     if ($new) {
       throw new Exception(
         "Invalid 'new' value for PHID transaction. Value should contain only ".
         "keys '+' (add PHIDs), '-' (remove PHIDs) and '=' (set PHIDS).");
     }
 
     $result = array();
 
     foreach ($old as $phid) {
       if ($new_set !== null && empty($new_set[$phid])) {
         continue;
       }
       $result[$phid] = $phid;
     }
 
     if ($new_set !== null) {
       foreach ($new_set as $phid) {
         $result[$phid] = $phid;
       }
     }
 
     foreach ($new_add as $phid) {
       $result[$phid] = $phid;
     }
 
     foreach ($new_rem as $phid) {
       unset($result[$phid]);
     }
 
     return array_values($result);
   }
 
   protected function getEdgeTransactionNewValue(
     PhabricatorApplicationTransaction $xaction) {
 
     $new = $xaction->getNewValue();
     $new_add = idx($new, '+', array());
     unset($new['+']);
     $new_rem = idx($new, '-', array());
     unset($new['-']);
     $new_set = idx($new, '=', null);
     unset($new['=']);
 
     if ($new) {
       throw new Exception(
         "Invalid 'new' value for Edge transaction. Value should contain only ".
         "keys '+' (add edges), '-' (remove edges) and '=' (set edges).");
     }
 
     $old = $xaction->getOldValue();
 
     $lists = array($new_set, $new_add, $new_rem);
     foreach ($lists as $list) {
       $this->checkEdgeList($list);
     }
 
     $result = array();
     foreach ($old as $dst_phid => $edge) {
       if ($new_set !== null && empty($new_set[$dst_phid])) {
         continue;
       }
       $result[$dst_phid] = $this->normalizeEdgeTransactionValue(
         $xaction,
         $edge,
         $dst_phid);
     }
 
     if ($new_set !== null) {
       foreach ($new_set as $dst_phid => $edge) {
         $result[$dst_phid] = $this->normalizeEdgeTransactionValue(
           $xaction,
           $edge,
           $dst_phid);
       }
     }
 
     foreach ($new_add as $dst_phid => $edge) {
       $result[$dst_phid] = $this->normalizeEdgeTransactionValue(
         $xaction,
         $edge,
         $dst_phid);
     }
 
     foreach ($new_rem as $dst_phid => $edge) {
       unset($result[$dst_phid]);
     }
 
     return $result;
   }
 
   private function checkEdgeList($list) {
     if (!$list) {
       return;
     }
     foreach ($list as $key => $item) {
       if (phid_get_type($key) === PhabricatorPHIDConstants::PHID_TYPE_UNKNOWN) {
         throw new Exception(
           "Edge transactions must have destination PHIDs as in edge ".
           "lists (found key '{$key}').");
       }
       if (!is_array($item) && $item !== $key) {
         throw new Exception(
           "Edge transactions must have PHIDs or edge specs as values ".
           "(found value '{$item}').");
       }
     }
   }
 
   private function normalizeEdgeTransactionValue(
     PhabricatorApplicationTransaction $xaction,
     $edge,
     $dst_phid) {
 
     if (!is_array($edge)) {
       if ($edge != $dst_phid) {
         throw new Exception(
           pht(
             'Transaction edge data must either be the edge PHID or an edge '.
             'specification dictionary.'));
       }
       $edge = array();
     } else {
       foreach ($edge as $key => $value) {
         switch ($key) {
           case 'src':
           case 'dst':
           case 'type':
           case 'data':
           case 'dateCreated':
           case 'dateModified':
           case 'seq':
           case 'dataID':
             break;
           default:
             throw new Exception(
               pht(
                 'Transaction edge specification contains unexpected key '.
                 '"%s".',
                 $key));
         }
       }
     }
 
     $edge['dst'] = $dst_phid;
 
     $edge_type = $xaction->getMetadataValue('edge:type');
     if (empty($edge['type'])) {
       $edge['type'] = $edge_type;
     } else {
       if ($edge['type'] != $edge_type) {
         $this_type = $edge['type'];
         throw new Exception(
           "Edge transaction includes edge of type '{$this_type}', but ".
           "transaction is of type '{$edge_type}'. Each edge transaction must ".
           "alter edges of only one type.");
       }
     }
 
     if (!isset($edge['data'])) {
       $edge['data'] = array();
     }
 
     return $edge;
   }
 
   protected function sortTransactions(array $xactions) {
     $head = array();
     $tail = array();
 
     // Move bare comments to the end, so the actions precede them.
     foreach ($xactions as $xaction) {
       $type = $xaction->getTransactionType();
       if ($type == PhabricatorTransactions::TYPE_COMMENT) {
         $tail[] = $xaction;
       } else {
         $head[] = $xaction;
       }
     }
 
     return array_values(array_merge($head, $tail));
   }
 
 
   protected function filterTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $type_comment = PhabricatorTransactions::TYPE_COMMENT;
 
     $no_effect = array();
     $has_comment = false;
     $any_effect = false;
     foreach ($xactions as $key => $xaction) {
       if ($this->transactionHasEffect($object, $xaction)) {
         if ($xaction->getTransactionType() != $type_comment) {
           $any_effect = true;
         }
       } else if ($xaction->getIgnoreOnNoEffect()) {
         unset($xactions[$key]);
       } else {
         $no_effect[$key] = $xaction;
       }
       if ($xaction->hasComment()) {
         $has_comment = true;
       }
     }
 
     if (!$no_effect) {
       return $xactions;
     }
 
     if (!$this->getContinueOnNoEffect() && !$this->getIsPreview()) {
       throw new PhabricatorApplicationTransactionNoEffectException(
         $no_effect,
         $any_effect,
         $has_comment);
     }
 
     if (!$any_effect && !$has_comment) {
       // If we only have empty comment transactions, just drop them all.
       return array();
     }
 
     foreach ($no_effect as $key => $xaction) {
       if ($xaction->getComment()) {
         $xaction->setTransactionType($type_comment);
         $xaction->setOldValue(null);
         $xaction->setNewValue(null);
       } else {
         unset($xactions[$key]);
       }
     }
 
     return $xactions;
   }
 
 
   /**
    * Hook for validating transactions. This callback will be invoked for each
    * available transaction type, even if an edit does not apply any transactions
    * of that type. This allows you to raise exceptions when required fields are
    * missing, by detecting that the object has no field value and there is no
    * transaction which sets one.
    *
    * @param PhabricatorLiskDAO Object being edited.
    * @param string Transaction type to validate.
    * @param list<PhabricatorApplicationTransaction> Transactions of given type,
    *   which may be empty if the edit does not apply any transactions of the
    *   given type.
    * @return list<PhabricatorApplicationTransactionValidationError> List of
    *   validation errors.
    */
   protected function validateTransaction(
     PhabricatorLiskDAO $object,
     $type,
     array $xactions) {
 
     $errors = array();
     switch ($type) {
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         $errors[] = $this->validatePolicyTransaction(
           $object,
           $xactions,
           $type,
           PhabricatorPolicyCapability::CAN_VIEW);
         break;
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         $errors[] = $this->validatePolicyTransaction(
           $object,
           $xactions,
           $type,
           PhabricatorPolicyCapability::CAN_EDIT);
         break;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $groups = array();
         foreach ($xactions as $xaction) {
           $groups[$xaction->getMetadataValue('customfield:key')][] = $xaction;
         }
 
         $field_list = PhabricatorCustomField::getObjectFields(
           $object,
           PhabricatorCustomField::ROLE_EDIT);
         $field_list->setViewer($this->getActor());
 
         $role_xactions = PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS;
         foreach ($field_list->getFields() as $field) {
           if (!$field->shouldEnableForRole($role_xactions)) {
             continue;
           }
           $errors[] = $field->validateApplicationTransactions(
             $this,
             $type,
             idx($groups, $field->getFieldKey(), array()));
         }
         break;
     }
 
     return array_mergev($errors);
   }
 
   private function validatePolicyTransaction(
     PhabricatorLiskDAO $object,
     array $xactions,
     $transaction_type,
     $capability) {
 
     $actor = $this->requireActor();
     $errors = array();
     // Note $this->xactions is necessary; $xactions is $this->xactions of
     // $transaction_type
     $policy_object = $this->adjustObjectForPolicyChecks(
       $object,
       $this->xactions);
 
     // Make sure the user isn't editing away their ability to $capability this
     // object.
     foreach ($xactions as $xaction) {
       try {
         PhabricatorPolicyFilter::requireCapabilityWithForcedPolicy(
           $actor,
           $policy_object,
           $capability,
           $xaction->getNewValue());
       } catch (PhabricatorPolicyException $ex) {
         $errors[] = new PhabricatorApplicationTransactionValidationError(
           $transaction_type,
           pht('Invalid'),
           pht(
             'You can not select this %s policy, because you would no longer '.
             'be able to %s the object.',
             $capability,
             $capability),
           $xaction);
       }
     }
 
     if ($this->getIsNewObject()) {
       if (!$xactions) {
         $has_capability = PhabricatorPolicyFilter::hasCapability(
           $actor,
           $policy_object,
           $capability);
         if (!$has_capability) {
           $errors[] = new PhabricatorApplicationTransactionValidationError(
             $transaction_type,
             pht('Invalid'),
             pht('The selected %s policy excludes you. Choose a %s policy '.
                 'which allows you to %s the object.',
             $capability,
             $capability,
             $capability));
         }
       }
     }
 
     return $errors;
   }
 
   protected function adjustObjectForPolicyChecks(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     return clone $object;
   }
 
   /**
    * Check for a missing text field.
    *
    * A text field is missing if the object has no value and there are no
    * transactions which set a value, or if the transactions remove the value.
    * This method is intended to make implementing @{method:validateTransaction}
    * more convenient:
    *
    *   $missing = $this->validateIsEmptyTextField(
    *     $object->getName(),
    *     $xactions);
    *
    * This will return `true` if the net effect of the object and transactions
    * is an empty field.
    *
    * @param wild Current field value.
    * @param list<PhabricatorApplicationTransaction> Transactions editing the
    *          field.
    * @return bool True if the field will be an empty text field after edits.
    */
   protected function validateIsEmptyTextField($field_value, array $xactions) {
     if (strlen($field_value) && empty($xactions)) {
       return false;
     }
 
     if ($xactions && strlen(last($xactions)->getNewValue())) {
       return false;
     }
 
     return true;
   }
 
 
 /* -(  Implicit CCs  )------------------------------------------------------- */
 
 
   /**
    * When a user interacts with an object, we might want to add them to CC.
    */
   final public function applyImplicitCC(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     if (!($object instanceof PhabricatorSubscribableInterface)) {
       // If the object isn't subscribable, we can't CC them.
       return $xactions;
     }
 
     $actor_phid = $this->requireActor()->getPHID();
     if ($object->isAutomaticallySubscribed($actor_phid)) {
       // If they're auto-subscribed, don't CC them.
       return $xactions;
     }
 
     $should_cc = false;
     foreach ($xactions as $xaction) {
       if ($this->shouldImplyCC($object, $xaction)) {
         $should_cc = true;
         break;
       }
     }
 
     if (!$should_cc) {
       // Only some types of actions imply a CC (like adding a comment).
       return $xactions;
     }
 
     if ($object->getPHID()) {
       if (isset($this->subscribers[$actor_phid])) {
         // If the user is already subscribed, don't implicitly CC them.
         return $xactions;
       }
 
       $unsub = PhabricatorEdgeQuery::loadDestinationPHIDs(
         $object->getPHID(),
         PhabricatorEdgeConfig::TYPE_OBJECT_HAS_UNSUBSCRIBER);
       $unsub = array_fuse($unsub);
       if (isset($unsub[$actor_phid])) {
         // If the user has previously unsubscribed from this object explicitly,
         // don't implicitly CC them.
         return $xactions;
       }
     }
 
     $xaction = newv(get_class(head($xactions)), array());
     $xaction->setTransactionType(PhabricatorTransactions::TYPE_SUBSCRIBERS);
     $xaction->setNewValue(array('+' => array($actor_phid)));
 
     array_unshift($xactions, $xaction);
 
     return $xactions;
   }
 
   protected function shouldImplyCC(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     return $xaction->isCommentTransaction();
   }
 
 
 /* -(  Sending Mail  )------------------------------------------------------- */
 
 
   /**
    * @task mail
    */
   protected function shouldSendMail(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return false;
   }
 
 
   /**
    * @task mail
    */
   protected function sendMail(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $email_to = array_filter(array_unique($this->getMailTo($object)));
     $email_cc = array_filter(array_unique($this->getMailCC($object)));
 
     $phids = array_merge($email_to, $email_cc);
     $handles = id(new PhabricatorHandleQuery())
       ->setViewer($this->requireActor())
       ->withPHIDs($phids)
       ->execute();
 
     $template = $this->buildMailTemplate($object);
     $body = $this->buildMailBody($object, $xactions);
 
     $mail_tags = $this->getMailTags($object, $xactions);
     $action = $this->getMailAction($object, $xactions);
 
     $reply_handler = $this->buildReplyHandler($object);
     $reply_section = $reply_handler->getReplyHandlerInstructions();
     if ($reply_section !== null) {
       $body->addReplySection($reply_section);
     }
 
     $template
       ->setFrom($this->requireActor()->getPHID())
       ->setSubjectPrefix($this->getMailSubjectPrefix())
       ->setVarySubjectPrefix('['.$action.']')
       ->setThreadID($this->getMailThreadID($object), $this->getIsNewObject())
       ->setRelatedPHID($object->getPHID())
       ->setExcludeMailRecipientPHIDs($this->getExcludeMailRecipientPHIDs())
       ->setMailTags($mail_tags)
       ->setIsBulk(true)
       ->setBody($body->render());
 
     foreach ($body->getAttachments() as $attachment) {
       $template->addAttachment($attachment);
     }
 
     $herald_xscript = $this->getHeraldTranscript();
     if ($herald_xscript) {
       $herald_header = $herald_xscript->getXHeraldRulesHeader();
       $herald_header = HeraldTranscript::saveXHeraldRulesHeader(
         $object->getPHID(),
         $herald_header);
     } else {
       $herald_header = HeraldTranscript::loadXHeraldRulesHeader(
         $object->getPHID());
     }
 
     if ($herald_header) {
       $template->addHeader('X-Herald-Rules', $herald_header);
     }
 
     if ($this->getParentMessageID()) {
       $template->setParentMessageID($this->getParentMessageID());
     }
 
     $mails = $reply_handler->multiplexMail(
         $template,
         array_select_keys($handles, $email_to),
         array_select_keys($handles, $email_cc));
 
     foreach ($mails as $mail) {
       $mail->saveAndSend();
     }
 
     $template->addTos($email_to);
     $template->addCCs($email_cc);
 
     return $template;
   }
 
   protected function getMailThreadID(PhabricatorLiskDAO $object) {
     return $object->getPHID();
   }
 
 
   /**
    * @task mail
    */
   protected function getStrongestAction(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return last(msort($xactions, 'getActionStrength'));
   }
 
 
   /**
    * @task mail
    */
   protected function buildReplyHandler(PhabricatorLiskDAO $object) {
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function getMailSubjectPrefix() {
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function getMailTags(
     PhabricatorLiskDAO $object,
     array $xactions) {
     $tags = array();
 
     foreach ($xactions as $xaction) {
       $tags[] = $xaction->getMailTags();
     }
 
     return array_mergev($tags);
   }
 
   /**
    * @task mail
    */
   protected function getMailAction(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return $this->getStrongestAction($object, $xactions)->getActionName();
   }
 
 
   /**
    * @task mail
    */
   protected function buildMailTemplate(PhabricatorLiskDAO $object) {
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function getMailTo(PhabricatorLiskDAO $object) {
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function getMailCC(PhabricatorLiskDAO $object) {
     if ($object instanceof PhabricatorSubscribableInterface) {
       return $this->subscribers;
     }
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function buildMailBody(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $headers = array();
     $comments = array();
 
     foreach ($xactions as $xaction) {
       if ($xaction->shouldHideForMail($xactions)) {
         continue;
       }
 
       $header = $xaction->getTitleForMail();
       if ($header !== null) {
         $headers[] = $header;
       }
 
       $comment = $xaction->getBodyForMail();
       if ($comment !== null) {
         $comments[] = $comment;
       }
     }
 
     $body = new PhabricatorMetaMTAMailBody();
     $body->addRawSection(implode("\n", $headers));
 
     foreach ($comments as $comment) {
       $body->addRawSection($comment);
     }
 
     if ($object instanceof PhabricatorCustomFieldInterface) {
       $field_list = PhabricatorCustomField::getObjectFields(
         $object,
         PhabricatorCustomField::ROLE_TRANSACTIONMAIL);
       $field_list->setViewer($this->getActor());
       $field_list->readFieldsFromStorage($object);
 
       foreach ($field_list->getFields() as $field) {
         $field->updateTransactionMailBody(
           $body,
           $this,
           $xactions);
       }
     }
 
     return $body;
   }
 
 
 /* -(  Publishing Feed Stories  )-------------------------------------------- */
 
 
   /**
    * @task feed
    */
   protected function shouldPublishFeedStory(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return false;
   }
 
 
   /**
    * @task feed
    */
   protected function getFeedStoryType() {
     return 'PhabricatorApplicationTransactionFeedStory';
   }
 
 
   /**
    * @task feed
    */
   protected function getFeedRelatedPHIDs(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     return array(
       $object->getPHID(),
       $this->requireActor()->getPHID(),
     );
   }
 
 
   /**
    * @task feed
    */
   protected function getFeedNotifyPHIDs(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     return array_unique(array_merge(
       $this->getMailTo($object),
       $this->getMailCC($object)));
   }
 
 
   /**
    * @task feed
    */
   protected function getFeedStoryData(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $xactions = msort($xactions, 'getActionStrength');
     $xactions = array_reverse($xactions);
 
     return array(
       'objectPHID'        => $object->getPHID(),
       'transactionPHIDs'  => mpull($xactions, 'getPHID'),
     );
   }
 
 
   /**
    * @task feed
    */
   protected function publishFeedStory(
     PhabricatorLiskDAO $object,
     array $xactions,
     array $mailed_phids) {
 
     $xactions = mfilter($xactions, 'shouldHideForFeed', true);
     $related_phids = $this->getFeedRelatedPHIDs($object, $xactions);
     $subscribed_phids = $this->getFeedNotifyPHIDs($object, $xactions);
 
     $story_type = $this->getFeedStoryType();
     $story_data = $this->getFeedStoryData($object, $xactions);
 
     id(new PhabricatorFeedStoryPublisher())
       ->setStoryType($story_type)
       ->setStoryData($story_data)
       ->setStoryTime(time())
       ->setStoryAuthorPHID($this->requireActor()->getPHID())
       ->setRelatedPHIDs($related_phids)
       ->setPrimaryObjectPHID($object->getPHID())
       ->setSubscribedPHIDs($subscribed_phids)
       ->setMailRecipientPHIDs($mailed_phids)
       ->publish();
   }
 
 
 /* -(  Search Index  )------------------------------------------------------- */
 
 
   /**
    * @task search
    */
   protected function supportsSearch() {
     return false;
   }
 
 
 /* -(  Herald Integration )-------------------------------------------------- */
 
 
   protected function shouldApplyHeraldRules(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return false;
   }
 
   protected function buildHeraldAdapter(
     PhabricatorLiskDAO $object,
     array $xactions) {
     throw new Exception('No herald adapter specified.');
   }
 
   private function setHeraldAdapter(HeraldAdapter $adapter) {
     $this->heraldAdapter = $adapter;
     return $this;
   }
 
   protected function getHeraldAdapter() {
     return $this->heraldAdapter;
   }
 
   private function setHeraldTranscript(HeraldTranscript $transcript) {
     $this->heraldTranscript = $transcript;
     return $this;
   }
 
   protected function getHeraldTranscript() {
     return $this->heraldTranscript;
   }
 
   private function applyHeraldRules(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $adapter = $this->buildHeraldAdapter($object, $xactions);
     $adapter->setContentSource($this->getContentSource());
     $adapter->setIsNewObject($this->getIsNewObject());
     $xscript = HeraldEngine::loadAndApplyRules($adapter);
 
     $this->setHeraldAdapter($adapter);
     $this->setHeraldTranscript($xscript);
 
     return $this->didApplyHeraldRules($object, $adapter, $xscript);
   }
 
   protected function didApplyHeraldRules(
     PhabricatorLiskDAO $object,
     HeraldAdapter $adapter,
     HeraldTranscript $transcript) {
     return array();
   }
 
 
 /* -(  Custom Fields  )------------------------------------------------------ */
 
 
   /**
    * @task customfield
    */
   private function getCustomFieldForTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     $field_key = $xaction->getMetadataValue('customfield:key');
     if (!$field_key) {
       throw new Exception(
         "Custom field transaction has no 'customfield:key'!");
     }
 
     $field = PhabricatorCustomField::getObjectField(
       $object,
       PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS,
       $field_key);
 
     if (!$field) {
       throw new Exception(
         "Custom field transaction has invalid 'customfield:key'; field ".
         "'{$field_key}' is disabled or does not exist.");
     }
 
     if (!$field->shouldAppearInApplicationTransactions()) {
       throw new Exception(
         "Custom field transaction '{$field_key}' does not implement ".
         "integration for ApplicationTransactions.");
     }
 
     $field->setViewer($this->getActor());
 
     return $field;
   }
 
 
 /* -(  Files  )-------------------------------------------------------------- */
 
 
   /**
    * Extract the PHIDs of any files which these transactions attach.
    *
    * @task files
    */
   private function extractFilePHIDs(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $blocks = array();
     foreach ($xactions as $xaction) {
       $blocks[] = $this->getRemarkupBlocksFromTransaction($xaction);
     }
     $blocks = array_mergev($blocks);
 
     $phids = array();
     if ($blocks) {
       $phids[] = PhabricatorMarkupEngine::extractFilePHIDsFromEmbeddedFiles(
         $blocks);
     }
 
     foreach ($xactions as $xaction) {
       $phids[] = $this->extractFilePHIDsFromCustomTransaction(
         $object,
         $xaction);
     }
 
     $phids = array_unique(array_filter(array_mergev($phids)));
     if (!$phids) {
       return array();
     }
 
     // Only let a user attach files they can actually see, since this would
     // otherwise let you access any file by attaching it to an object you have
     // view permission on.
 
     $files = id(new PhabricatorFileQuery())
       ->setViewer($this->getActor())
       ->withPHIDs($phids)
       ->execute();
 
     return mpull($files, 'getPHID');
   }
 
   /**
    * @task files
    */
   protected function extractFilePHIDsFromCustomTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     return array();
   }
 
 
   /**
    * @task files
    */
   private function attachFiles(
     PhabricatorLiskDAO $object,
     array $file_phids) {
 
     if (!$file_phids) {
       return;
     }
 
     $editor = id(new PhabricatorEdgeEditor())
       ->setActor($this->getActor());
 
     // TODO: Edge-based events were almost certainly a terrible idea. If we
     // don't suppress this event, the Maniphest listener reenters and adds
     // more transactions. Just suppress it until that can get cleaned up.
     $editor->setSuppressEvents(true);
 
     $src = $object->getPHID();
     $type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_FILE;
     foreach ($file_phids as $dst) {
       $editor->addEdge($src, $type, $dst);
     }
 
     $editor->save();
   }
 
 }
diff --git a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
index f62d2951e7..922a8f8325 100644
--- a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
+++ b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
@@ -1,805 +1,882 @@
 <?php
 
 abstract class PhabricatorApplicationTransaction
   extends PhabricatorLiskDAO
   implements PhabricatorPolicyInterface {
 
   const TARGET_TEXT = 'text';
   const TARGET_HTML = 'html';
 
   protected $phid;
   protected $objectPHID;
   protected $authorPHID;
   protected $viewPolicy;
   protected $editPolicy;
 
   protected $commentPHID;
   protected $commentVersion = 0;
   protected $transactionType;
   protected $oldValue;
   protected $newValue;
   protected $metadata = array();
 
   protected $contentSource;
 
   private $comment;
   private $commentNotLoaded;
 
   private $handles;
   private $renderingTarget = self::TARGET_HTML;
   private $transactionGroup = array();
   private $viewer = self::ATTACHABLE;
   private $object = self::ATTACHABLE;
   private $oldValueHasBeenSet = false;
 
   private $ignoreOnNoEffect;
 
 
   /**
    * Flag this transaction as a pure side-effect which should be ignored when
    * applying transactions if it has no effect, even if transaction application
    * would normally fail. This both provides users with better error messages
    * and allows transactions to perform optional side effects.
    */
   public function setIgnoreOnNoEffect($ignore) {
     $this->ignoreOnNoEffect = $ignore;
     return $this;
   }
 
   public function getIgnoreOnNoEffect() {
     return $this->ignoreOnNoEffect;
   }
 
   public function shouldGenerateOldValue() {
     switch ($this->getTransactionType()) {
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        return false;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         return false;
     }
     return true;
   }
 
   abstract public function getApplicationTransactionType();
 
   private function getApplicationObjectTypeName() {
     $types = PhabricatorPHIDType::getAllTypes();
 
     $type = idx($types, $this->getApplicationTransactionType());
     if ($type) {
       return $type->getTypeName();
     }
 
     return pht('Object');
   }
 
   public function getApplicationTransactionCommentObject() {
     throw new Exception("Not implemented!");
   }
 
   public function getApplicationTransactionViewObject() {
     return new PhabricatorApplicationTransactionView();
   }
 
   public function getMetadataValue($key, $default = null) {
     return idx($this->metadata, $key, $default);
   }
 
   public function setMetadataValue($key, $value) {
     $this->metadata[$key] = $value;
     return $this;
   }
 
   public function generatePHID() {
     $type = PhabricatorApplicationTransactionPHIDTypeTransaction::TYPECONST;
     $subtype = $this->getApplicationTransactionType();
 
     return PhabricatorPHID::generateNewPHID($type, $subtype);
   }
 
   public function getConfiguration() {
     return array(
       self::CONFIG_AUX_PHID => true,
       self::CONFIG_SERIALIZATION => array(
         'oldValue' => self::SERIALIZATION_JSON,
         'newValue' => self::SERIALIZATION_JSON,
         'metadata' => self::SERIALIZATION_JSON,
       ),
     ) + parent::getConfiguration();
   }
 
   public function setContentSource(PhabricatorContentSource $content_source) {
     $this->contentSource = $content_source->serialize();
     return $this;
   }
 
   public function getContentSource() {
     return PhabricatorContentSource::newFromSerialized($this->contentSource);
   }
 
   public function hasComment() {
     return $this->getComment() && strlen($this->getComment()->getContent());
   }
 
   public function getComment() {
     if ($this->commentNotLoaded) {
       throw new Exception("Comment for this transaction was not loaded.");
     }
     return $this->comment;
   }
 
   public function attachComment(
     PhabricatorApplicationTransactionComment $comment) {
     $this->comment = $comment;
     $this->commentNotLoaded = false;
     return $this;
   }
 
   public function setCommentNotLoaded($not_loaded) {
     $this->commentNotLoaded = $not_loaded;
     return $this;
   }
 
   public function attachObject($object) {
     $this->object = $object;
     return $this;
   }
 
   public function getObject() {
     return $this->assertAttached($this->object);
   }
 
   public function getRemarkupBlocks() {
     $blocks = array();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           $custom_blocks = $field->getApplicationTransactionRemarkupBlocks(
             $this);
           foreach ($custom_blocks as $custom_block) {
             $blocks[] = $custom_block;
           }
         }
         break;
     }
 
     if ($this->getComment()) {
       $blocks[] = $this->getComment()->getContent();
     }
 
     return $blocks;
   }
 
   public function setOldValue($value) {
     $this->oldValueHasBeenSet = true;
     $this->writeField('oldValue', $value);
     return $this;
   }
 
   public function hasOldValue() {
     return $this->oldValueHasBeenSet;
   }
 
 
 /* -(  Rendering  )---------------------------------------------------------- */
 
   public function setRenderingTarget($rendering_target) {
     $this->renderingTarget = $rendering_target;
     return $this;
   }
 
   public function getRenderingTarget() {
     return $this->renderingTarget;
   }
 
   public function attachViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
     return $this;
   }
 
   public function getViewer() {
     return $this->assertAttached($this->viewer);
   }
 
   public function getRequiredHandlePHIDs() {
     $phids = array();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     $phids[] = array($this->getAuthorPHID());
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           $phids[] = $field->getApplicationTransactionRequiredHandlePHIDs(
             $this);
         }
         break;
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $phids[] = $old;
         $phids[] = $new;
         break;
       case PhabricatorTransactions::TYPE_EDGE:
         $phids[] = ipull($old, 'dst');
         $phids[] = ipull($new, 'dst');
         break;
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         if (!PhabricatorPolicyQuery::isGlobalPolicy($old)) {
           $phids[] = array($old);
         }
         if (!PhabricatorPolicyQuery::isGlobalPolicy($new)) {
           $phids[] = array($new);
         }
         break;
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        $phid = $this->getMetadataValue('harbormaster:buildablePHID');
+        if ($phid) {
+          $phids[] = array($phid);
+        }
+        break;
     }
 
     return array_mergev($phids);
   }
 
   public function setHandles(array $handles) {
     $this->handles = $handles;
     return $this;
   }
 
   public function getHandle($phid) {
     if (empty($this->handles[$phid])) {
       throw new Exception(
         pht(
           'Transaction ("%s") requires a handle ("%s") that it did not '.
           'load.',
           $this->getPHID(),
           $phid));
     }
     return $this->handles[$phid];
   }
 
   public function getHandleIfExists($phid) {
     return idx($this->handles, $phid);
   }
 
   public function getHandles() {
     if ($this->handles === null) {
       throw new Exception(
         'Transaction requires handles and it did not load them.'
       );
     }
     return $this->handles;
   }
 
   public function renderHandleLink($phid) {
     if ($this->renderingTarget == self::TARGET_HTML) {
       return $this->getHandle($phid)->renderLink();
     } else {
       return $this->getHandle($phid)->getLinkName();
     }
   }
 
   public function renderHandleList(array $phids) {
     $links = array();
     foreach ($phids as $phid) {
       $links[] = $this->renderHandleLink($phid);
     }
     if ($this->renderingTarget == self::TARGET_HTML) {
       return phutil_implode_html(', ', $links);
     } else {
       return implode(', ', $links);
     }
   }
 
   private function renderSubscriberList(array $phids, $change_type) {
     if ($this->getRenderingTarget() == self::TARGET_TEXT) {
       return $this->renderHandleList($phids);
     } else {
       $handles = array_select_keys($this->getHandles(), $phids);
       return id(new SubscriptionListStringBuilder())
         ->setHandles($handles)
         ->setObjectPHID($this->getPHID())
         ->buildTransactionString($change_type);
     }
   }
 
   public function renderPolicyName($phid) {
     $policy = PhabricatorPolicy::newFromPolicyAndHandle(
       $phid,
       $this->getHandleIfExists($phid));
     if ($this->renderingTarget == self::TARGET_HTML) {
       $output = $policy->renderDescription();
     } else {
       $output = hsprintf('%s', $policy->getFullName());
     }
     return $output;
   }
 
   public function getIcon() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return 'comment';
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return 'message';
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return 'lock';
       case PhabricatorTransactions::TYPE_EDGE:
         return 'link';
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        return 'wrench';
     }
 
     return 'edit';
   }
 
   public function getColor() {
+    switch ($this->getTransactionType()) {
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        switch ($this->getNewValue()) {
+          case HarbormasterBuildable::STATUS_PASSED:
+            return 'green';
+          case HarbormasterBuildable::STATUS_FAILED:
+            return 'red';
+        }
+        break;
+    }
     return null;
   }
 
   protected function getTransactionCustomField() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $key = $this->getMetadataValue('customfield:key');
         if (!$key) {
           return null;
         }
 
         $field = PhabricatorCustomField::getObjectField(
           $this->getObject(),
           PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS,
           $key);
         if (!$field) {
           return null;
         }
 
         $field->setViewer($this->getViewer());
         return $field;
     }
 
     return null;
   }
 
   public function shouldHide() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         if ($this->getOldValue() === null) {
           return true;
         } else {
           return false;
         }
         break;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->shouldHideInApplicationTransactions($this);
         }
     }
 
     return false;
   }
 
   public function shouldHideForMail(array $xactions) {
+    switch ($this->getTransactionType()) {
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        switch ($this->getNewValue()) {
+          case HarbormasterBuildable::STATUS_PASSED:
+            // For now, just never send mail when builds pass. We might let
+            // you customize this later, but in most cases this is probably
+            // completely uninteresting.
+            return true;
+        }
+    }
+
     return $this->shouldHide();
   }
 
   public function shouldHideForFeed() {
     return $this->shouldHide();
   }
 
   public function getTitleForMail() {
     return id(clone $this)->setRenderingTarget('text')->getTitle();
   }
 
   public function getBodyForMail() {
     $comment = $this->getComment();
     if ($comment && strlen($comment->getContent())) {
       return $comment->getContent();
     }
     return null;
   }
 
   public function getNoEffectDescription() {
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht('You can not post an empty comment.');
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         return pht(
           'This %s already has that view policy.',
           $this->getApplicationObjectTypeName());
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         return pht(
           'This %s already has that edit policy.',
           $this->getApplicationObjectTypeName());
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return pht(
           'This %s already has that join policy.',
           $this->getApplicationObjectTypeName());
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return pht(
           'All users are already subscribed to this %s.',
           $this->getApplicationObjectTypeName());
       case PhabricatorTransactions::TYPE_EDGE:
         return pht('Edges already exist; transaction has no effect.');
     }
 
     return pht('Transaction has no effect.');
   }
 
   public function getTitle() {
     $author_phid = $this->getAuthorPHID();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht(
           '%s added a comment.',
           $this->renderHandleLink($author_phid));
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         return pht(
           '%s changed the visibility of this %s from "%s" to "%s".',
           $this->renderHandleLink($author_phid),
           $this->getApplicationObjectTypeName(),
           $this->renderPolicyName($old),
           $this->renderPolicyName($new));
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         return pht(
           '%s changed the edit policy of this %s from "%s" to "%s".',
           $this->renderHandleLink($author_phid),
           $this->getApplicationObjectTypeName(),
           $this->renderPolicyName($old),
           $this->renderPolicyName($new));
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return pht(
           '%s changed the join policy of this %s from "%s" to "%s".',
           $this->renderHandleLink($author_phid),
           $this->getApplicationObjectTypeName(),
           $this->renderPolicyName($old),
           $this->renderPolicyName($new));
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $add = array_diff($new, $old);
         $rem = array_diff($old, $new);
 
         if ($add && $rem) {
           return pht(
             '%s edited subscriber(s), added %d: %s; removed %d: %s.',
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderSubscriberList($add, 'add'),
             count($rem),
             $this->renderSubscriberList($rem, 'rem'));
         } else if ($add) {
           return pht(
             '%s added %d subscriber(s): %s.',
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderSubscriberList($add, 'add'));
         } else if ($rem) {
           return pht(
             '%s removed %d subscriber(s): %s.',
             $this->renderHandleLink($author_phid),
             count($rem),
             $this->renderSubscriberList($rem, 'rem'));
         } else {
           // This is used when rendering previews, before the user actually
           // selects any CCs.
           return pht(
             '%s updated subscribers...',
             $this->renderHandleLink($author_phid));
         }
         break;
       case PhabricatorTransactions::TYPE_EDGE:
         $new = ipull($new, 'dst');
         $old = ipull($old, 'dst');
         $add = array_diff($new, $old);
         $rem = array_diff($old, $new);
         $type = $this->getMetadata('edge:type');
         $type = head($type);
 
         if ($add && $rem) {
           $string = PhabricatorEdgeConfig::getEditStringForEdgeType($type);
           return pht(
             $string,
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderHandleList($add),
             count($rem),
             $this->renderHandleList($rem));
         } else if ($add) {
           $string = PhabricatorEdgeConfig::getAddStringForEdgeType($type);
           return pht(
             $string,
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderHandleList($add));
         } else if ($rem) {
           $string = PhabricatorEdgeConfig::getRemoveStringForEdgeType($type);
           return pht(
             $string,
             $this->renderHandleLink($author_phid),
             count($rem),
             $this->renderHandleList($rem));
         } else {
           return pht(
             '%s edited edge metadata.',
             $this->renderHandleLink($author_phid));
         }
 
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionTitle($this);
         } else {
           return pht(
             '%s edited a custom field.',
             $this->renderHandleLink($author_phid));
         }
 
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        switch ($this->getNewValue()) {
+          case HarbormasterBuildable::STATUS_PASSED:
+            return pht(
+              '%s completed building %s.',
+              $this->renderHandleLink($author_phid),
+              $this->renderHandleLink(
+                $this->getMetadataValue('harbormaster:buildablePHID')));
+          case HarbormasterBuildable::STATUS_FAILED:
+            return pht(
+              '%s failed to build %s!',
+              $this->renderHandleLink($author_phid),
+              $this->renderHandleLink(
+                $this->getMetadataValue('harbormaster:buildablePHID')));
+          default:
+            return null;
+        }
+
       default:
         return pht(
           '%s edited this %s.',
           $this->renderHandleLink($author_phid),
           $this->getApplicationObjectTypeName());
     }
   }
 
   public function getTitleForFeed(PhabricatorFeedStory $story) {
     $author_phid = $this->getAuthorPHID();
     $object_phid = $this->getObjectPHID();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht(
           '%s added a comment to %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         return pht(
           '%s changed the visibility for %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         return pht(
           '%s changed the edit policy for %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return pht(
           '%s changed the join policy for %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return pht(
           '%s updated subscribers of %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_EDGE:
         $type = $this->getMetadata('edge:type');
         $type = head($type);
         $string = PhabricatorEdgeConfig::getFeedStringForEdgeType($type);
         return pht(
           $string,
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionTitleForFeed($this, $story);
         } else {
           return pht(
             '%s edited a custom field on %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid));
         }
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        switch ($this->getNewValue()) {
+          case HarbormasterBuildable::STATUS_PASSED:
+            return pht(
+              '%s completed building %s for %s.',
+              $this->renderHandleLink($author_phid),
+              $this->renderHandleLink(
+                $this->getMetadataValue('harbormaster:buildablePHID')),
+              $this->renderHandleLink($object_phid));
+          case HarbormasterBuildable::STATUS_FAILED:
+            return pht(
+              '%s failed to build %s for %s.',
+              $this->renderHandleLink($author_phid),
+              $this->renderHandleLink(
+                $this->getMetadataValue('harbormaster:buildablePHID')),
+              $this->renderHandleLink($object_phid));
+          default:
+            return null;
+        }
 
     }
 
     return $this->getTitle();
   }
 
   public function getBodyForFeed(PhabricatorFeedStory $story) {
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     $body = null;
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         $text = $this->getComment()->getContent();
         $body = phutil_escape_html_newlines(
           phutil_utf8_shorten($text, 128));
         break;
     }
     return $body;
   }
 
   public function getActionStrength() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return 0.5;
     }
     return 1.0;
   }
 
   public function isCommentTransaction() {
     if ($this->hasComment()) {
       return true;
     }
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return true;
     }
 
     return false;
   }
 
   public function getActionName() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht('Commented On');
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return pht('Changed Policy');
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return pht('Changed Subscribers');
+      case PhabricatorTransactions::TYPE_BUILDABLE:
+        switch ($this->getNewValue()) {
+          case HarbormasterBuildable::STATUS_PASSED:
+            return pht('Build Passed');
+          case HarbormasterBuildable::STATUS_FAILED:
+            return pht('Build Failed');
+          default:
+            return pht('Build Status');
+        }
       default:
         return pht('Updated');
     }
   }
 
   public function getMailTags() {
     return array();
   }
 
   public function hasChangeDetails() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionHasChangeDetails($this);
         }
         break;
     }
     return false;
   }
 
   public function renderChangeDetails(PhabricatorUser $viewer) {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionChangeDetails($this, $viewer);
         }
         break;
     }
 
     return $this->renderTextCorpusChangeDetails();
   }
 
   public function renderTextCorpusChangeDetails(
     PhabricatorUser $viewer,
     $old,
     $new) {
 
     require_celerity_resource('differential-changeset-view-css');
 
     $view = id(new PhabricatorApplicationTransactionTextDiffDetailView())
       ->setUser($viewer)
       ->setOldText($old)
       ->setNewText($new);
 
     return $view->render();
   }
 
   public function attachTransactionGroup(array $group) {
     assert_instances_of($group, 'PhabricatorApplicationTransaction');
     $this->transactionGroup = $group;
     return $this;
   }
 
   public function getTransactionGroup() {
     return $this->transactionGroup;
   }
 
   /**
    * Should this transaction be visually grouped with an existing transaction
    * group?
    *
    * @param list<PhabricatorApplicationTransaction> List of transactions.
    * @return bool True to display in a group with the other transactions.
    */
   public function shouldDisplayGroupWith(array $group) {
     $this_source = null;
     if ($this->getContentSource()) {
       $this_source = $this->getContentSource()->getSource();
     }
 
     foreach ($group as $xaction) {
       // Don't group transactions by different authors.
       if ($xaction->getAuthorPHID() != $this->getAuthorPHID()) {
         return false;
       }
 
       // Don't group transactions for different objects.
       if ($xaction->getObjectPHID() != $this->getObjectPHID()) {
         return false;
       }
 
       // Don't group anything into a group which already has a comment.
       if ($xaction->isCommentTransaction()) {
         return false;
       }
 
       // Don't group transactions from different content sources.
       $other_source = null;
       if ($xaction->getContentSource()) {
         $other_source = $xaction->getContentSource()->getSource();
       }
 
       if ($other_source != $this_source) {
         return false;
       }
 
       // Don't group transactions which happened more than 2 minutes apart.
       $apart = abs($xaction->getDateCreated() - $this->getDateCreated());
       if ($apart > (60 * 2)) {
         return false;
       }
     }
 
     return true;
   }
 
   public function renderExtraInformationLink() {
     $herald_xscript_id = $this->getMetadataValue('herald:transcriptID');
 
     if ($herald_xscript_id) {
       return phutil_tag(
         'a',
         array(
           'href' => '/herald/transcript/'.$herald_xscript_id.'/',
         ),
         pht('View Herald Transcript'));
     }
 
     return null;
   }
 
 
 /* -(  PhabricatorPolicyInterface Implementation  )-------------------------- */
 
 
   public function getCapabilities() {
     return array(
       PhabricatorPolicyCapability::CAN_VIEW,
       PhabricatorPolicyCapability::CAN_EDIT,
     );
   }
 
   public function getPolicy($capability) {
     switch ($capability) {
       case PhabricatorPolicyCapability::CAN_VIEW:
         return $this->getViewPolicy();
       case PhabricatorPolicyCapability::CAN_EDIT:
         return $this->getEditPolicy();
     }
   }
 
   public function hasAutomaticCapability($capability, PhabricatorUser $viewer) {
     return ($viewer->getPHID() == $this->getAuthorPHID());
   }
 
   public function describeAutomaticCapability($capability) {
     // TODO: (T603) Exact policies are unclear here.
     return null;
   }
 
 
 }