diff --git a/src/applications/harbormaster/constants/HarbormasterBuildStatus.php b/src/applications/harbormaster/constants/HarbormasterBuildStatus.php
--- a/src/applications/harbormaster/constants/HarbormasterBuildStatus.php
+++ b/src/applications/harbormaster/constants/HarbormasterBuildStatus.php
@@ -53,10 +53,6 @@
     return $this->getProperty('isComplete');
   }
 
-  public function isPending() {
-    return $this->getProperty('isPending');
-  }
-
   public function isPassed() {
     return ($this->key === self::STATUS_PASSED);
   }
@@ -81,6 +77,10 @@
     return ($this->key === self::PENDING_PAUSING);
   }
 
+  public function isPending() {
+    return ($this->key === self::STATUS_PENDING);
+  }
+
   public function getIconIcon() {
     return $this->getProperty('icon');
   }
@@ -170,7 +170,6 @@
         'color.ansi' => 'yellow',
         'isBuilding' => false,
         'isComplete' => false,
-        'isPending' => false,
       ),
       self::STATUS_PENDING => array(
         'name' => pht('Pending'),
@@ -179,7 +178,6 @@
         'color.ansi' => 'yellow',
         'isBuilding' => true,
         'isComplete' => false,
-        'isPending' => false,
       ),
       self::STATUS_BUILDING => array(
         'name' => pht('Building'),
@@ -188,7 +186,6 @@
         'color.ansi' => 'yellow',
         'isBuilding' => true,
         'isComplete' => false,
-        'isPending' => false,
       ),
       self::STATUS_PASSED => array(
         'name' => pht('Passed'),
@@ -197,7 +194,6 @@
         'color.ansi' => 'green',
         'isBuilding' => false,
         'isComplete' => true,
-        'isPending' => false,
       ),
       self::STATUS_FAILED => array(
         'name' => pht('Failed'),
@@ -206,7 +202,6 @@
         'color.ansi' => 'red',
         'isBuilding' => false,
         'isComplete' => true,
-        'isPending' => false,
       ),
       self::STATUS_ABORTED => array(
         'name' => pht('Aborted'),
@@ -215,7 +210,6 @@
         'color.ansi' => 'red',
         'isBuilding' => false,
         'isComplete' => true,
-        'isPending' => false,
       ),
       self::STATUS_ERROR => array(
         'name' => pht('Unexpected Error'),
@@ -224,7 +218,6 @@
         'color.ansi' => 'red',
         'isBuilding' => false,
         'isComplete' => true,
-        'isPending' => false,
       ),
       self::STATUS_PAUSED => array(
         'name' => pht('Paused'),
@@ -233,7 +226,6 @@
         'color.ansi' => 'yellow',
         'isBuilding' => false,
         'isComplete' => false,
-        'isPending' => false,
       ),
       self::STATUS_DEADLOCKED => array(
         'name' => pht('Deadlocked'),
@@ -242,7 +234,6 @@
         'color.ansi' => 'red',
         'isBuilding' => false,
         'isComplete' => true,
-        'isPending' => false,
       ),
       self::PENDING_PAUSING => array(
         'name' => pht('Pausing'),
@@ -251,7 +242,6 @@
         'color.ansi' => 'red',
         'isBuilding' => false,
         'isComplete' => false,
-        'isPending' => true,
       ),
       self::PENDING_RESUMING => array(
         'name' => pht('Resuming'),
@@ -260,7 +250,6 @@
         'color.ansi' => 'red',
         'isBuilding' => false,
         'isComplete' => false,
-        'isPending' => true,
       ),
       self::PENDING_RESTARTING => array(
         'name' => pht('Restarting'),
@@ -269,7 +258,6 @@
         'color.ansi' => 'red',
         'isBuilding' => false,
         'isComplete' => false,
-        'isPending' => true,
       ),
       self::PENDING_ABORTING => array(
         'name' => pht('Aborting'),
@@ -278,7 +266,6 @@
         'color.ansi' => 'red',
         'isBuilding' => false,
         'isComplete' => false,
-        'isPending' => true,
       ),
     );
   }
diff --git a/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php b/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php
--- a/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php
+++ b/src/applications/harbormaster/editor/HarbormasterBuildTransactionEditor.php
@@ -65,48 +65,32 @@
     HarbormasterBuild $build,
     HarbormasterBuildTransaction $xaction) {
 
-    $command = $xaction->getNewValue();
+    $actor = $this->getActor();
+    $message_type = $xaction->getNewValue();
 
-    switch ($command) {
-      case HarbormasterBuildCommand::COMMAND_RESTART:
-        $issuable = $build->canRestartBuild();
+    // TODO: Restore logic that tests if the command can issue without causing
+    // anything to lapse into an invalid state. This should not be the same
+    // as the logic which powers the web UI: for example, if an "abort" is
+    // queued we want to disable "Abort" in the web UI, but should obviously
+    // process it here.
+
+    switch ($message_type) {
+      case HarbormasterBuildCommand::COMMAND_ABORT:
+        // TODO: This should move to external effects, perhaps.
+        $build->releaseAllArtifacts($actor);
+        $build->setBuildStatus(HarbormasterBuildStatus::STATUS_ABORTED);
         break;
-      case HarbormasterBuildCommand::COMMAND_PAUSE:
-        $issuable = $build->canPauseBuild();
+      case HarbormasterBuildCommand::COMMAND_RESTART:
+        $build->restartBuild($actor);
+        $build->setBuildStatus(HarbormasterBuildStatus::STATUS_BUILDING);
         break;
       case HarbormasterBuildCommand::COMMAND_RESUME:
-        $issuable = $build->canResumeBuild();
+        $build->setBuildStatus(HarbormasterBuildStatus::STATUS_BUILDING);
         break;
-      case HarbormasterBuildCommand::COMMAND_ABORT:
-        $issuable = $build->canAbortBuild();
+      case HarbormasterBuildCommand::COMMAND_PAUSE:
+        $build->setBuildStatus(HarbormasterBuildStatus::STATUS_PAUSED);
         break;
-      default:
-        throw new Exception(pht('Unknown command %s', $command));
-    }
-
-    if (!$issuable) {
-      return;
     }
-
-    $actor = $this->getActor();
-    if (!$build->canIssueCommand($actor, $command)) {
-      return;
-    }
-
-    HarbormasterBuildMessage::initializeNewMessage($actor)
-      ->setAuthorPHID($xaction->getAuthorPHID())
-      ->setReceiverPHID($build->getPHID())
-      ->setType($command)
-      ->save();
-
-    PhabricatorWorker::scheduleTask(
-      'HarbormasterBuildWorker',
-      array(
-        'buildID' => $build->getID(),
-      ),
-      array(
-        'objectPHID' => $build->getPHID(),
-      ));
   }
 
   protected function applyCustomExternalTransaction(
diff --git a/src/applications/harbormaster/engine/HarbormasterBuildEngine.php b/src/applications/harbormaster/engine/HarbormasterBuildEngine.php
--- a/src/applications/harbormaster/engine/HarbormasterBuildEngine.php
+++ b/src/applications/harbormaster/engine/HarbormasterBuildEngine.php
@@ -49,6 +49,7 @@
   }
 
   public function continueBuild() {
+    $viewer = $this->getViewer();
     $build = $this->getBuild();
 
     $lock_key = 'harbormaster.build:'.$build->getID();
@@ -68,7 +69,7 @@
 
       $lock->unlock();
 
-      $this->releaseAllArtifacts($build);
+      $build->releaseAllArtifacts($viewer);
 
       throw $ex;
     }
@@ -99,56 +100,58 @@
 
     // If we are no longer building for any reason, release all artifacts.
     if (!$build->isBuilding()) {
-      $this->releaseAllArtifacts($build);
+      $build->releaseAllArtifacts($viewer);
     }
   }
 
   private function updateBuild(HarbormasterBuild $build) {
-    if ($build->isAborting()) {
-      $this->releaseAllArtifacts($build);
-      $build->setBuildStatus(HarbormasterBuildStatus::STATUS_ABORTED);
-      $build->save();
-    }
+    $viewer = $this->getViewer();
 
-    if (($build->getBuildStatus() == HarbormasterBuildStatus::STATUS_PENDING) ||
-        ($build->isRestarting())) {
-      $this->restartBuild($build);
-      $build->setBuildStatus(HarbormasterBuildStatus::STATUS_BUILDING);
-      $build->save();
-    }
+    $content_source = PhabricatorContentSource::newForSource(
+      PhabricatorDaemonContentSource::SOURCECONST);
 
-    if ($build->isResuming()) {
-      $build->setBuildStatus(HarbormasterBuildStatus::STATUS_BUILDING);
-      $build->save();
+    $acting_phid = $viewer->getPHID();
+    if (!$acting_phid) {
+      $acting_phid = id(new PhabricatorHarbormasterApplication())->getPHID();
     }
 
-    if ($build->isPausing() && !$build->isComplete()) {
-      $build->setBuildStatus(HarbormasterBuildStatus::STATUS_PAUSED);
-      $build->save();
-    }
+    $editor = $build->getApplicationTransactionEditor()
+      ->setActor($viewer)
+      ->setActingAsPHID($acting_phid)
+      ->setContentSource($content_source)
+      ->setContinueOnNoEffect(true)
+      ->setContinueOnMissingFields(true);
 
-    $build->markUnprocessedMessagesAsProcessed();
+    $xactions = array();
 
-    if ($build->getBuildStatus() == HarbormasterBuildStatus::STATUS_BUILDING) {
-      $this->updateBuildSteps($build);
-    }
-  }
+    $messages = $build->getUnprocessedMessagesForApply();
+    foreach ($messages as $message) {
+      $message_type = $message->getType();
 
-  private function restartBuild(HarbormasterBuild $build) {
+      $xactions[] = $build->getApplicationTransactionTemplate()
+        ->setAuthorPHID($message->getAuthorPHID())
+        ->setTransactionType(HarbormasterBuildTransaction::TYPE_COMMAND)
+        ->setNewValue($message_type);
+    }
 
-    // We're restarting the build, so release all previous artifacts.
-    $this->releaseAllArtifacts($build);
+    if (!$xactions) {
+      if ($build->isPending()) {
+        // TODO: This should be a transaction.
 
-    // Increment the build generation counter on the build.
-    $build->setBuildGeneration($build->getBuildGeneration() + 1);
+        $build->restartBuild($viewer);
+        $build->setBuildStatus(HarbormasterBuildStatus::STATUS_BUILDING);
+        $build->save();
+      }
+    }
 
-    // Currently running targets should periodically check their build
-    // generation (which won't have changed) against the build's generation.
-    // If it is different, they will automatically stop what they're doing
-    // and abort.
+    if ($xactions) {
+      $editor->applyTransactions($build, $xactions);
+      $build->markUnprocessedMessagesAsProcessed();
+    }
 
-    // Previously we used to delete targets, logs and artifacts here. Instead,
-    // leave them around so users can view previous generations of this build.
+    if ($build->getBuildStatus() == HarbormasterBuildStatus::STATUS_BUILDING) {
+      $this->updateBuildSteps($build);
+    }
   }
 
   private function updateBuildSteps(HarbormasterBuild $build) {
@@ -596,29 +599,6 @@
       ->publishBuildable($old, $new);
   }
 
-  private function releaseAllArtifacts(HarbormasterBuild $build) {
-    $targets = id(new HarbormasterBuildTargetQuery())
-      ->setViewer(PhabricatorUser::getOmnipotentUser())
-      ->withBuildPHIDs(array($build->getPHID()))
-      ->withBuildGenerations(array($build->getBuildGeneration()))
-      ->execute();
-
-    if (count($targets) === 0) {
-      return;
-    }
-
-    $target_phids = mpull($targets, 'getPHID');
-
-    $artifacts = id(new HarbormasterBuildArtifactQuery())
-      ->setViewer(PhabricatorUser::getOmnipotentUser())
-      ->withBuildTargetPHIDs($target_phids)
-      ->withIsReleased(false)
-      ->execute();
-    foreach ($artifacts as $artifact) {
-      $artifact->releaseArtifact();
-    }
-  }
-
   private function releaseQueuedArtifacts() {
     foreach ($this->artifactReleaseQueue as $key => $artifact) {
       $artifact->releaseArtifact();
diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuild.php b/src/applications/harbormaster/storage/build/HarbormasterBuild.php
--- a/src/applications/harbormaster/storage/build/HarbormasterBuild.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuild.php
@@ -207,13 +207,50 @@
     return $this->getBuildStatusObject()->isFailed();
   }
 
+  public function isPending() {
+    return $this->getBuildstatusObject()->isPending();
+  }
+
   public function getURI() {
     $id = $this->getID();
     return "/harbormaster/build/{$id}/";
   }
 
   public function getBuildPendingStatusObject() {
+    list($pending_status) = $this->getUnprocessedMessageState();
+
+    if ($pending_status !== null) {
+      return HarbormasterBuildStatus::newBuildStatusObject($pending_status);
+    }
+
+    return $this->getBuildStatusObject();
+  }
 
+  protected function getBuildStatusObject() {
+    $status_key = $this->getBuildStatus();
+    return HarbormasterBuildStatus::newBuildStatusObject($status_key);
+  }
+
+  public function getObjectName() {
+    return pht('Build %d', $this->getID());
+  }
+
+
+/* -(  Build Messages  )----------------------------------------------------- */
+
+
+  private function getUnprocessedMessages() {
+    return $this->assertAttached($this->unprocessedMessages);
+  }
+
+  public function getUnprocessedMessagesForApply() {
+    $unprocessed_state = $this->getUnprocessedMessageState();
+    list($pending_status, $apply_messages) = $unprocessed_state;
+
+    return $apply_messages;
+  }
+
+  private function getUnprocessedMessageState() {
     // NOTE: If a build has multiple unprocessed messages, we'll ignore
     // messages that are obsoleted by a later or stronger message.
     //
@@ -230,24 +267,30 @@
     $is_pausing = false;
     $is_resuming = false;
 
+    $apply_messages = array();
+
     foreach ($this->getUnprocessedMessages() as $message_object) {
       $message_type = $message_object->getType();
       switch ($message_type) {
         case HarbormasterBuildCommand::COMMAND_RESTART:
           $is_restarting = true;
           $is_aborting = false;
+          $apply_messages = array($message_object);
           break;
         case HarbormasterBuildCommand::COMMAND_ABORT:
           $is_aborting = true;
           $is_restarting = false;
+          $apply_messages = array($message_object);
           break;
         case HarbormasterBuildCommand::COMMAND_PAUSE:
           $is_pausing = true;
           $is_resuming = false;
+          $apply_messages = array($message_object);
           break;
         case HarbormasterBuildCommand::COMMAND_RESUME:
           $is_resuming = true;
           $is_pausing = false;
+          $apply_messages = array($message_object);
           break;
       }
     }
@@ -263,28 +306,7 @@
       $pending_status = HarbormasterBuildStatus::PENDING_RESUMING;
     }
 
-    if ($pending_status !== null) {
-      return HarbormasterBuildStatus::newBuildStatusObject($pending_status);
-    }
-
-    return $this->getBuildStatusObject();
-  }
-
-  protected function getBuildStatusObject() {
-    $status_key = $this->getBuildStatus();
-    return HarbormasterBuildStatus::newBuildStatusObject($status_key);
-  }
-
-  public function getObjectName() {
-    return pht('Build %d', $this->getID());
-  }
-
-
-/* -(  Build Messages  )----------------------------------------------------- */
-
-
-  private function getUnprocessedMessages() {
-    return $this->assertAttached($this->unprocessedMessages);
+    return array($pending_status, $apply_messages);
   }
 
   public function attachUnprocessedMessages(array $messages) {
@@ -475,32 +497,61 @@
   }
 
   public function sendMessage(PhabricatorUser $viewer, $message_type) {
-    // TODO: This should not be an editor transaction, but there are plans to
-    // merge BuildCommand into BuildMessage which should moot this. As this
-    // exists today, it can race against BuildEngine.
-
-    // This is a bogus content source, but this whole flow should be obsolete
-    // soon.
-    $content_source = PhabricatorContentSource::newForSource(
-      PhabricatorConsoleContentSource::SOURCECONST);
-
-    $editor = id(new HarbormasterBuildTransactionEditor())
-      ->setActor($viewer)
-      ->setContentSource($content_source)
-      ->setContinueOnNoEffect(true)
-      ->setContinueOnMissingFields(true);
-
-    $viewer_phid = $viewer->getPHID();
-    if (!$viewer_phid) {
-      $acting_phid = id(new PhabricatorHarbormasterApplication())->getPHID();
-      $editor->setActingAsPHID($acting_phid);
+    HarbormasterBuildMessage::initializeNewMessage($viewer)
+      ->setReceiverPHID($this->getPHID())
+      ->setType($message_type)
+      ->save();
+
+    PhabricatorWorker::scheduleTask(
+      'HarbormasterBuildWorker',
+      array(
+        'buildID' => $this->getID(),
+      ),
+      array(
+        'objectPHID' => $this->getPHID(),
+        'containerPHID' => $this->getBuildablePHID(),
+      ));
+  }
+
+  public function releaseAllArtifacts(PhabricatorUser $viewer) {
+    $targets = id(new HarbormasterBuildTargetQuery())
+      ->setViewer($viewer)
+      ->withBuildPHIDs(array($this->getPHID()))
+      ->withBuildGenerations(array($this->getBuildGeneration()))
+      ->execute();
+
+    if (!$targets) {
+      return;
     }
 
-    $xaction = id(new HarbormasterBuildTransaction())
-      ->setTransactionType(HarbormasterBuildTransaction::TYPE_COMMAND)
-      ->setNewValue($message_type);
+    $target_phids = mpull($targets, 'getPHID');
+
+    $artifacts = id(new HarbormasterBuildArtifactQuery())
+      ->setViewer($viewer)
+      ->withBuildTargetPHIDs($target_phids)
+      ->withIsReleased(false)
+      ->execute();
+    foreach ($artifacts as $artifact) {
+      $artifact->releaseArtifact();
+    }
+  }
+
+  public function restartBuild(PhabricatorUser $viewer) {
+    // TODO: This should become transactional.
+
+    // We're restarting the build, so release all previous artifacts.
+    $this->releaseAllArtifacts($viewer);
+
+    // Increment the build generation counter on the build.
+    $this->setBuildGeneration($this->getBuildGeneration() + 1);
+
+    // Currently running targets should periodically check their build
+    // generation (which won't have changed) against the build's generation.
+    // If it is different, they will automatically stop what they're doing
+    // and abort.
 
-    $editor->applyTransactions($this, array($xaction));
+    // Previously we used to delete targets, logs and artifacts here. Instead,
+    // leave them around so users can view previous generations of this build.
   }