diff --git a/src/applications/project/controller/PhabricatorProjectProfileController.php b/src/applications/project/controller/PhabricatorProjectProfileController.php
index 0a9bc602d2..81a172ae42 100644
--- a/src/applications/project/controller/PhabricatorProjectProfileController.php
+++ b/src/applications/project/controller/PhabricatorProjectProfileController.php
@@ -1,285 +1,299 @@
 <?php
 
 final class PhabricatorProjectProfileController
   extends PhabricatorProjectController {
 
   public function shouldAllowPublic() {
     return true;
   }
 
   public function handleRequest(AphrontRequest $request) {
     $response = $this->loadProject();
     if ($response) {
       return $response;
     }
 
     $viewer = $request->getUser();
     $project = $this->getProject();
     $id = $project->getID();
     $picture = $project->getProfileImageURI();
     $icon = $project->getDisplayIconIcon();
     $icon_name = $project->getDisplayIconName();
     $tag = id(new PHUITagView())
       ->setIcon($icon)
       ->setName($icon_name)
       ->addClass('project-view-header-tag')
       ->setType(PHUITagView::TYPE_SHADE);
 
     $header = id(new PHUIHeaderView())
       ->setHeader(array($project->getDisplayName(), $tag))
       ->setUser($viewer)
       ->setPolicyObject($project)
       ->setImage($picture)
       ->setProfileHeader(true);
 
     if ($project->getStatus() == PhabricatorProjectStatus::STATUS_ACTIVE) {
       $header->setStatus('fa-check', 'bluegrey', pht('Active'));
     } else {
       $header->setStatus('fa-ban', 'red', pht('Archived'));
     }
 
     $can_edit = PhabricatorPolicyFilter::hasCapability(
       $viewer,
       $project,
       PhabricatorPolicyCapability::CAN_EDIT);
 
     if ($can_edit) {
       $header->setImageEditURL($this->getApplicationURI("picture/{$id}/"));
     }
 
     $properties = $this->buildPropertyListView($project);
 
     $watch_action = $this->renderWatchAction($project);
     $header->addActionLink($watch_action);
 
     $milestone_list = $this->buildMilestoneList($project);
     $subproject_list = $this->buildSubprojectList($project);
 
     $member_list = id(new PhabricatorProjectMemberListView())
       ->setUser($viewer)
       ->setProject($project)
       ->setLimit(5)
       ->setBackground(PHUIBoxView::GREY)
       ->setUserPHIDs($project->getMemberPHIDs());
 
     $watcher_list = id(new PhabricatorProjectWatcherListView())
       ->setUser($viewer)
       ->setProject($project)
       ->setLimit(5)
       ->setBackground(PHUIBoxView::GREY)
       ->setUserPHIDs($project->getWatcherPHIDs());
 
     $nav = $this->getProfileMenu();
     $nav->selectFilter(PhabricatorProject::PANEL_PROFILE);
 
     $stories = id(new PhabricatorFeedQuery())
       ->setViewer($viewer)
       ->setFilterPHIDs(
         array(
           $project->getPHID(),
         ))
       ->setLimit(50)
       ->execute();
 
     $feed = $this->renderStories($stories);
     $feed = phutil_tag_div('project-view-feed', $feed);
 
     $columns = id(new PHUITwoColumnView())
       ->setMainColumn(
         array(
           $properties,
           $feed,
         ))
       ->setSideColumn(
         array(
           $milestone_list,
           $subproject_list,
           $member_list,
           $watcher_list,
         ));
 
     $crumbs = $this->buildApplicationCrumbs();
     $crumbs->setBorder(true);
 
     require_celerity_resource('project-view-css');
     $home = phutil_tag(
       'div',
       array(
         'class' => 'project-view-home',
       ),
       array(
         $header,
         $columns,
       ));
 
     return $this->newPage()
       ->setNavigation($nav)
       ->setCrumbs($crumbs)
       ->setTitle($project->getDisplayName())
       ->setPageObjectPHIDs(array($project->getPHID()))
       ->appendChild(
         array(
           $home,
         ));
   }
 
   private function buildPropertyListView(
     PhabricatorProject $project) {
     $request = $this->getRequest();
     $viewer = $request->getUser();
 
     $view = id(new PHUIPropertyListView())
       ->setUser($viewer)
       ->setObject($project);
 
     $field_list = PhabricatorCustomField::getObjectFields(
       $project,
       PhabricatorCustomField::ROLE_VIEW);
     $field_list->appendFieldsToPropertyList($project, $viewer, $view);
 
     if (!$view->hasAnyProperties()) {
       return null;
     }
 
     $view = id(new PHUIBoxView())
       ->setBorder(true)
       ->appendChild($view)
       ->addClass('project-view-properties');
 
     return $view;
   }
 
   private function renderStories(array $stories) {
     assert_instances_of($stories, 'PhabricatorFeedStory');
 
     $builder = new PhabricatorFeedBuilder($stories);
     $builder->setUser($this->getRequest()->getUser());
     $builder->setShowHovercards(true);
     $view = $builder->buildView();
 
     return $view;
   }
 
   private function renderWatchAction(PhabricatorProject $project) {
     $viewer = $this->getViewer();
-    $viewer_phid = $viewer->getPHID();
     $id = $project->getID();
 
-    $is_watcher = ($viewer_phid && $project->isUserWatcher($viewer_phid));
+    if (!$viewer->isLoggedIn()) {
+      $is_watcher = false;
+      $is_ancestor = false;
+    } else {
+      $viewer_phid = $viewer->getPHID();
+      $is_watcher = $project->isUserWatcher($viewer_phid);
+      $is_ancestor = $project->isUserAncestorWatcher($viewer_phid);
+    }
 
-    if (!$is_watcher) {
+    if ($is_ancestor && !$is_watcher) {
+      $watch_icon = 'fa-eye';
+      $watch_text = pht('Watching Ancestor');
+      $watch_href = "/project/watch/{$id}/?via=profile";
+      $watch_disabled = true;
+    } else if (!$is_watcher) {
       $watch_icon = 'fa-eye';
       $watch_text = pht('Watch Project');
       $watch_href = "/project/watch/{$id}/?via=profile";
+      $watch_disabled = false;
     } else {
       $watch_icon = 'fa-eye-slash';
       $watch_text = pht('Unwatch Project');
       $watch_href = "/project/unwatch/{$id}/?via=profile";
+      $watch_disabled = false;
     }
 
     $watch_icon = id(new PHUIIconView())
       ->setIcon($watch_icon);
 
     return id(new PHUIButtonView())
       ->setTag('a')
       ->setWorkflow(true)
       ->setIcon($watch_icon)
       ->setText($watch_text)
-      ->setHref($watch_href);
+      ->setHref($watch_href)
+      ->setDisabled($watch_disabled);
   }
 
   private function buildMilestoneList(PhabricatorProject $project) {
     if (!$project->getHasMilestones()) {
       return null;
     }
 
     $viewer = $this->getViewer();
     $id = $project->getID();
 
     $milestones = id(new PhabricatorProjectQuery())
       ->setViewer($viewer)
       ->withParentProjectPHIDs(array($project->getPHID()))
       ->needImages(true)
       ->withIsMilestone(true)
       ->withStatuses(
         array(
           PhabricatorProjectStatus::STATUS_ACTIVE,
         ))
       ->setOrderVector(array('milestoneNumber', 'id'))
       ->execute();
     if (!$milestones) {
       return null;
     }
 
     $milestone_list = id(new PhabricatorProjectListView())
       ->setUser($viewer)
       ->setProjects($milestones)
       ->renderList();
 
     $view_all = id(new PHUIButtonView())
       ->setTag('a')
       ->setIcon(
         id(new PHUIIconView())
           ->setIcon('fa-list-ul'))
       ->setText(pht('View All'))
       ->setHref("/project/subprojects/{$id}/");
 
     $header = id(new PHUIHeaderView())
       ->setHeader(pht('Milestones'))
       ->addActionLink($view_all);
 
     return id(new PHUIObjectBoxView())
       ->setHeader($header)
       ->setBackground(PHUIBoxView::GREY)
       ->setObjectList($milestone_list);
   }
 
   private function buildSubprojectList(PhabricatorProject $project) {
     if (!$project->getHasSubprojects()) {
       return null;
     }
 
     $viewer = $this->getViewer();
     $id = $project->getID();
 
     $limit = 25;
 
     $subprojects = id(new PhabricatorProjectQuery())
       ->setViewer($viewer)
       ->withParentProjectPHIDs(array($project->getPHID()))
       ->needImages(true)
       ->withStatuses(
         array(
           PhabricatorProjectStatus::STATUS_ACTIVE,
         ))
       ->withIsMilestone(false)
       ->setLimit($limit)
       ->execute();
     if (!$subprojects) {
       return null;
     }
 
     $subproject_list = id(new PhabricatorProjectListView())
       ->setUser($viewer)
       ->setProjects($subprojects)
       ->renderList();
 
     $view_all = id(new PHUIButtonView())
       ->setTag('a')
       ->setIcon(
         id(new PHUIIconView())
           ->setIcon('fa-list-ul'))
       ->setText(pht('View All'))
       ->setHref("/project/subprojects/{$id}/");
 
     $header = id(new PHUIHeaderView())
       ->setHeader(pht('Subprojects'))
       ->addActionLink($view_all);
 
     return id(new PHUIObjectBoxView())
       ->setHeader($header)
       ->setBackground(PHUIBoxView::GREY)
       ->setObjectList($subproject_list);
   }
 
 }
diff --git a/src/applications/project/controller/PhabricatorProjectWatchController.php b/src/applications/project/controller/PhabricatorProjectWatchController.php
index 9624a0b730..00117768e1 100644
--- a/src/applications/project/controller/PhabricatorProjectWatchController.php
+++ b/src/applications/project/controller/PhabricatorProjectWatchController.php
@@ -1,89 +1,115 @@
 <?php
 
 final class PhabricatorProjectWatchController
   extends PhabricatorProjectController {
 
   public function handleRequest(AphrontRequest $request) {
     $viewer = $request->getViewer();
     $id = $request->getURIData('id');
     $action = $request->getURIData('action');
 
     $project = id(new PhabricatorProjectQuery())
       ->setViewer($viewer)
       ->withIDs(array($id))
       ->needMembers(true)
       ->needWatchers(true)
       ->executeOne();
     if (!$project) {
       return new Aphront404Response();
     }
 
     $via = $request->getStr('via');
     if ($via == 'profile') {
       $done_uri = "/project/profile/{$id}/";
     } else {
       $done_uri = "/project/members/{$id}/";
     }
 
+    $is_watcher = $project->isUserWatcher($viewer->getPHID());
+    $is_ancestor = $project->isUserAncestorWatcher($viewer->getPHID());
+    if ($is_ancestor && !$is_watcher) {
+      $ancestor_phid = $project->getWatchedAncestorPHID($viewer->getPHID());
+      $handles = $viewer->loadHandles(array($ancestor_phid));
+      $ancestor_handle = $handles[$ancestor_phid];
+
+      return $this->newDialog()
+        ->setTitle(pht('Watching Ancestor'))
+        ->appendParagraph(
+          pht(
+            'You are already watching %s, an ancestor of this project, and '.
+            'are thus watching all of its subprojects.',
+            $ancestor_handle->renderTag()->render()))
+        ->addCancelbutton($done_uri);
+    }
+
     if ($request->isDialogFormPost()) {
       $edge_action = null;
       switch ($action) {
         case 'watch':
           $edge_action = '+';
           break;
         case 'unwatch':
           $edge_action = '-';
           break;
       }
 
       $type_watcher = PhabricatorObjectHasWatcherEdgeType::EDGECONST;
       $member_spec = array(
         $edge_action => array($viewer->getPHID() => $viewer->getPHID()),
       );
 
       $xactions = array();
       $xactions[] = id(new PhabricatorProjectTransaction())
         ->setTransactionType(PhabricatorTransactions::TYPE_EDGE)
         ->setMetadataValue('edge:type', $type_watcher)
         ->setNewValue($member_spec);
 
       $editor = id(new PhabricatorProjectTransactionEditor($project))
         ->setActor($viewer)
         ->setContentSourceFromRequest($request)
         ->setContinueOnNoEffect(true)
         ->setContinueOnMissingFields(true)
         ->applyTransactions($project, $xactions);
 
       return id(new AphrontRedirectResponse())->setURI($done_uri);
     }
 
     $dialog = null;
     switch ($action) {
       case 'watch':
         $title = pht('Watch Project?');
-        $body = pht(
+        $body = array();
+        $body[] = pht(
           'Watching a project will let you monitor it closely. You will '.
           'receive email and notifications about changes to every object '.
-          'associated with projects you watch.');
+          'tagged with projects you watch.');
+        $body[] = pht(
+          'Watching a project also watches all subprojects and milestones of '.
+          'that project.');
         $submit = pht('Watch Project');
         break;
       case 'unwatch':
         $title = pht('Unwatch Project?');
         $body = pht(
           'You will no longer receive email or notifications about every '.
           'object associated with this project.');
         $submit = pht('Unwatch Project');
         break;
       default:
         return new Aphront404Response();
     }
 
-    return $this->newDialog()
+    $dialog = $this->newDialog()
       ->setTitle($title)
       ->addHiddenInput('via', $via)
-      ->appendParagraph($body)
       ->addCancelButton($done_uri)
       ->addSubmitButton($submit);
+
+    foreach ((array)$body as $paragraph) {
+      $dialog->appendParagraph($paragraph);
+    }
+
+    return $dialog;
   }
 
 }
diff --git a/src/applications/project/query/PhabricatorProjectQuery.php b/src/applications/project/query/PhabricatorProjectQuery.php
index b72fa1cec2..9ce5fff77c 100644
--- a/src/applications/project/query/PhabricatorProjectQuery.php
+++ b/src/applications/project/query/PhabricatorProjectQuery.php
@@ -1,763 +1,765 @@
 <?php
 
 final class PhabricatorProjectQuery
   extends PhabricatorCursorPagedPolicyAwareQuery {
 
   private $ids;
   private $phids;
   private $memberPHIDs;
   private $slugs;
   private $slugNormals;
   private $slugMap;
   private $allSlugs;
   private $names;
   private $nameTokens;
   private $icons;
   private $colors;
   private $ancestorPHIDs;
   private $parentPHIDs;
   private $isMilestone;
   private $hasSubprojects;
   private $minDepth;
   private $maxDepth;
   private $minMilestoneNumber;
   private $maxMilestoneNumber;
 
   private $status       = 'status-any';
   const STATUS_ANY      = 'status-any';
   const STATUS_OPEN     = 'status-open';
   const STATUS_CLOSED   = 'status-closed';
   const STATUS_ACTIVE   = 'status-active';
   const STATUS_ARCHIVED = 'status-archived';
   private $statuses;
 
   private $needSlugs;
   private $needMembers;
   private $needAncestorMembers;
   private $needWatchers;
   private $needImages;
 
   public function withIDs(array $ids) {
     $this->ids = $ids;
     return $this;
   }
 
   public function withPHIDs(array $phids) {
     $this->phids = $phids;
     return $this;
   }
 
   public function withStatus($status) {
     $this->status = $status;
     return $this;
   }
 
   public function withStatuses(array $statuses) {
     $this->statuses = $statuses;
     return $this;
   }
 
   public function withMemberPHIDs(array $member_phids) {
     $this->memberPHIDs = $member_phids;
     return $this;
   }
 
   public function withSlugs(array $slugs) {
     $this->slugs = $slugs;
     return $this;
   }
 
   public function withNames(array $names) {
     $this->names = $names;
     return $this;
   }
 
   public function withNameTokens(array $tokens) {
     $this->nameTokens = array_values($tokens);
     return $this;
   }
 
   public function withIcons(array $icons) {
     $this->icons = $icons;
     return $this;
   }
 
   public function withColors(array $colors) {
     $this->colors = $colors;
     return $this;
   }
 
   public function withParentProjectPHIDs($parent_phids) {
     $this->parentPHIDs = $parent_phids;
     return $this;
   }
 
   public function withAncestorProjectPHIDs($ancestor_phids) {
     $this->ancestorPHIDs = $ancestor_phids;
     return $this;
   }
 
   public function withIsMilestone($is_milestone) {
     $this->isMilestone = $is_milestone;
     return $this;
   }
 
   public function withHasSubprojects($has_subprojects) {
     $this->hasSubprojects = $has_subprojects;
     return $this;
   }
 
   public function withDepthBetween($min, $max) {
     $this->minDepth = $min;
     $this->maxDepth = $max;
     return $this;
   }
 
   public function withMilestoneNumberBetween($min, $max) {
     $this->minMilestoneNumber = $min;
     $this->maxMilestoneNumber = $max;
     return $this;
   }
 
   public function needMembers($need_members) {
     $this->needMembers = $need_members;
     return $this;
   }
 
   public function needAncestorMembers($need_ancestor_members) {
     $this->needAncestorMembers = $need_ancestor_members;
     return $this;
   }
 
   public function needWatchers($need_watchers) {
     $this->needWatchers = $need_watchers;
     return $this;
   }
 
   public function needImages($need_images) {
     $this->needImages = $need_images;
     return $this;
   }
 
   public function needSlugs($need_slugs) {
     $this->needSlugs = $need_slugs;
     return $this;
   }
 
   public function newResultObject() {
     return new PhabricatorProject();
   }
 
   protected function getDefaultOrderVector() {
     return array('name');
   }
 
   public function getBuiltinOrders() {
     return array(
       'name' => array(
         'vector' => array('name'),
         'name' => pht('Name'),
       ),
     ) + parent::getBuiltinOrders();
   }
 
   public function getOrderableColumns() {
     return parent::getOrderableColumns() + array(
       'name' => array(
         'table' => $this->getPrimaryTableAlias(),
         'column' => 'name',
         'reverse' => true,
         'type' => 'string',
         'unique' => true,
       ),
       'milestoneNumber' => array(
         'table' => $this->getPrimaryTableAlias(),
         'column' => 'milestoneNumber',
         'type' => 'int',
       ),
     );
   }
 
   protected function getPagingValueMap($cursor, array $keys) {
     $project = $this->loadCursorObject($cursor);
     return array(
       'name' => $project->getName(),
     );
   }
 
   public function getSlugMap() {
     if ($this->slugMap === null) {
       throw new PhutilInvalidStateException('execute');
     }
     return $this->slugMap;
   }
 
   protected function willExecute() {
     $this->slugMap = array();
     $this->slugNormals = array();
     $this->allSlugs = array();
     if ($this->slugs) {
       foreach ($this->slugs as $slug) {
         if (PhabricatorSlug::isValidProjectSlug($slug)) {
           $normal = PhabricatorSlug::normalizeProjectSlug($slug);
           $this->slugNormals[$slug] = $normal;
           $this->allSlugs[$normal] = $normal;
         }
 
         // NOTE: At least for now, we query for the normalized slugs but also
         // for the slugs exactly as entered. This allows older projects with
         // slugs that are no longer valid to continue to work.
         $this->allSlugs[$slug] = $slug;
       }
     }
   }
 
   protected function loadPage() {
     return $this->loadStandardPage($this->newResultObject());
   }
 
   protected function willFilterPage(array $projects) {
     $ancestor_paths = array();
     foreach ($projects as $project) {
       foreach ($project->getAncestorProjectPaths() as $path) {
         $ancestor_paths[$path] = $path;
       }
     }
 
     if ($ancestor_paths) {
       $ancestors = id(new PhabricatorProject())->loadAllWhere(
         'projectPath IN (%Ls)',
         $ancestor_paths);
     } else {
       $ancestors = array();
     }
 
     $projects = $this->linkProjectGraph($projects, $ancestors);
 
     $viewer_phid = $this->getViewer()->getPHID();
 
     $material_type = PhabricatorProjectMaterializedMemberEdgeType::EDGECONST;
     $watcher_type = PhabricatorObjectHasWatcherEdgeType::EDGECONST;
 
     $types = array();
     $types[] = $material_type;
     if ($this->needWatchers) {
       $types[] = $watcher_type;
     }
 
     $all_graph = $this->getAllReachableAncestors($projects);
 
-    if ($this->needAncestorMembers) {
+    if ($this->needAncestorMembers || $this->needWatchers) {
       $src_projects = $all_graph;
     } else {
       $src_projects = $projects;
     }
 
     $all_sources = array();
     foreach ($src_projects as $project) {
+      // For milestones, we need parent members.
       if ($project->isMilestone()) {
-        $phid = $project->getParentProjectPHID();
-      } else {
-        $phid = $project->getPHID();
+        $parent_phid = $project->getParentProjectPHID();
+        $all_sources[$parent_phid] = $parent_phid;
       }
+
+      $phid = $project->getPHID();
       $all_sources[$phid] = $phid;
     }
 
     $edge_query = id(new PhabricatorEdgeQuery())
       ->withSourcePHIDs($all_sources)
       ->withEdgeTypes($types);
 
     $need_all_edges =
       $this->needMembers ||
       $this->needWatchers ||
       $this->needAncestorMembers;
 
     // If we only need to know if the viewer is a member, we can restrict
     // the query to just their PHID.
     $any_edges = true;
     if (!$need_all_edges) {
       if ($viewer_phid) {
         $edge_query->withDestinationPHIDs(array($viewer_phid));
       } else {
         // If we don't need members or watchers and don't have a viewer PHID
         // (viewer is logged-out or omnipotent), they'll never be a member
         // so we don't need to issue this query at all.
         $any_edges = false;
       }
     }
 
     if ($any_edges) {
       $edge_query->execute();
     }
 
     $membership_projects = array();
     foreach ($src_projects as $project) {
       $project_phid = $project->getPHID();
 
       if ($project->isMilestone()) {
         $source_phids = array($project->getParentProjectPHID());
       } else {
         $source_phids = array($project_phid);
       }
 
       if ($any_edges) {
         $member_phids = $edge_query->getDestinationPHIDs(
           $source_phids,
           array($material_type));
       } else {
         $member_phids = array();
       }
 
       if (in_array($viewer_phid, $member_phids)) {
         $membership_projects[$project_phid] = $project;
       }
 
       if ($this->needMembers || $this->needAncestorMembers) {
         $project->attachMemberPHIDs($member_phids);
       }
 
       if ($this->needWatchers) {
         $watcher_phids = $edge_query->getDestinationPHIDs(
-          $source_phids,
+          array($project_phid),
           array($watcher_type));
         $project->attachWatcherPHIDs($watcher_phids);
         $project->setIsUserWatcher(
           $viewer_phid,
           in_array($viewer_phid, $watcher_phids));
       }
     }
 
     // If we loaded ancestor members, we've already populated membership
     // lists above, so we can skip this step.
     if (!$this->needAncestorMembers) {
       $member_graph = $this->getAllReachableAncestors($membership_projects);
 
       foreach ($all_graph as $phid => $project) {
         $is_member = isset($member_graph[$phid]);
         $project->setIsUserMember($viewer_phid, $is_member);
       }
     }
 
     return $projects;
   }
 
   protected function didFilterPage(array $projects) {
     if ($this->needImages) {
       $default = null;
 
       $file_phids = mpull($projects, 'getProfileImagePHID');
       $file_phids = array_filter($file_phids);
       if ($file_phids) {
         $files = id(new PhabricatorFileQuery())
           ->setParentQuery($this)
           ->setViewer($this->getViewer())
           ->withPHIDs($file_phids)
           ->execute();
         $files = mpull($files, null, 'getPHID');
       } else {
         $files = array();
       }
 
       foreach ($projects as $project) {
         $file = idx($files, $project->getProfileImagePHID());
         if (!$file) {
           if (!$default) {
             $default = PhabricatorFile::loadBuiltin(
               $this->getViewer(),
               'project.png');
           }
           $file = $default;
         }
         $project->attachProfileImageFile($file);
       }
     }
 
     $this->loadSlugs($projects);
 
     return $projects;
   }
 
   protected function buildWhereClauseParts(AphrontDatabaseConnection $conn) {
     $where = parent::buildWhereClauseParts($conn);
 
     if ($this->status != self::STATUS_ANY) {
       switch ($this->status) {
         case self::STATUS_OPEN:
         case self::STATUS_ACTIVE:
           $filter = array(
             PhabricatorProjectStatus::STATUS_ACTIVE,
           );
           break;
         case self::STATUS_CLOSED:
         case self::STATUS_ARCHIVED:
           $filter = array(
             PhabricatorProjectStatus::STATUS_ARCHIVED,
           );
           break;
         default:
           throw new Exception(
             pht(
               "Unknown project status '%s'!",
               $this->status));
       }
       $where[] = qsprintf(
         $conn,
         'status IN (%Ld)',
         $filter);
     }
 
     if ($this->statuses !== null) {
       $where[] = qsprintf(
         $conn,
         'status IN (%Ls)',
         $this->statuses);
     }
 
     if ($this->ids !== null) {
       $where[] = qsprintf(
         $conn,
         'id IN (%Ld)',
         $this->ids);
     }
 
     if ($this->phids !== null) {
       $where[] = qsprintf(
         $conn,
         'phid IN (%Ls)',
         $this->phids);
     }
 
     if ($this->memberPHIDs !== null) {
       $where[] = qsprintf(
         $conn,
         'e.dst IN (%Ls)',
         $this->memberPHIDs);
     }
 
     if ($this->slugs !== null) {
       $where[] = qsprintf(
         $conn,
         'slug.slug IN (%Ls)',
         $this->allSlugs);
     }
 
     if ($this->names !== null) {
       $where[] = qsprintf(
         $conn,
         'name IN (%Ls)',
         $this->names);
     }
 
     if ($this->icons !== null) {
       $where[] = qsprintf(
         $conn,
         'icon IN (%Ls)',
         $this->icons);
     }
 
     if ($this->colors !== null) {
       $where[] = qsprintf(
         $conn,
         'color IN (%Ls)',
         $this->colors);
     }
 
     if ($this->parentPHIDs !== null) {
       $where[] = qsprintf(
         $conn,
         'parentProjectPHID IN (%Ls)',
         $this->parentPHIDs);
     }
 
     if ($this->ancestorPHIDs !== null) {
       $ancestor_paths = queryfx_all(
         $conn,
         'SELECT projectPath, projectDepth FROM %T WHERE phid IN (%Ls)',
         id(new PhabricatorProject())->getTableName(),
         $this->ancestorPHIDs);
       if (!$ancestor_paths) {
         throw new PhabricatorEmptyQueryException();
       }
 
       $sql = array();
       foreach ($ancestor_paths as $ancestor_path) {
         $sql[] = qsprintf(
           $conn,
           '(projectPath LIKE %> AND projectDepth > %d)',
           $ancestor_path['projectPath'],
           $ancestor_path['projectDepth']);
       }
 
       $where[] = '('.implode(' OR ', $sql).')';
 
       $where[] = qsprintf(
         $conn,
         'parentProjectPHID IS NOT NULL');
     }
 
     if ($this->isMilestone !== null) {
       if ($this->isMilestone) {
         $where[] = qsprintf(
           $conn,
           'milestoneNumber IS NOT NULL');
       } else {
         $where[] = qsprintf(
           $conn,
           'milestoneNumber IS NULL');
       }
     }
 
 
     if ($this->hasSubprojects !== null) {
       $where[] = qsprintf(
         $conn,
         'hasSubprojects = %d',
         (int)$this->hasSubprojects);
     }
 
     if ($this->minDepth !== null) {
       $where[] = qsprintf(
         $conn,
         'projectDepth >= %d',
         $this->minDepth);
     }
 
     if ($this->maxDepth !== null) {
       $where[] = qsprintf(
         $conn,
         'projectDepth <= %d',
         $this->maxDepth);
     }
 
     if ($this->minMilestoneNumber !== null) {
       $where[] = qsprintf(
         $conn,
         'milestoneNumber >= %d',
         $this->minMilestoneNumber);
     }
 
     if ($this->maxMilestoneNumber !== null) {
       $where[] = qsprintf(
         $conn,
         'milestoneNumber <= %d',
         $this->maxMilestoneNumber);
     }
 
     return $where;
   }
 
   protected function shouldGroupQueryResultRows() {
     if ($this->memberPHIDs || $this->nameTokens) {
       return true;
     }
     return parent::shouldGroupQueryResultRows();
   }
 
   protected function buildJoinClauseParts(AphrontDatabaseConnection $conn) {
     $joins = parent::buildJoinClauseParts($conn);
 
     if ($this->memberPHIDs !== null) {
       $joins[] = qsprintf(
         $conn,
         'JOIN %T e ON e.src = p.phid AND e.type = %d',
         PhabricatorEdgeConfig::TABLE_NAME_EDGE,
         PhabricatorProjectMaterializedMemberEdgeType::EDGECONST);
     }
 
     if ($this->slugs !== null) {
       $joins[] = qsprintf(
         $conn,
         'JOIN %T slug on slug.projectPHID = p.phid',
         id(new PhabricatorProjectSlug())->getTableName());
     }
 
     if ($this->nameTokens !== null) {
       foreach ($this->nameTokens as $key => $token) {
         $token_table = 'token_'.$key;
         $joins[] = qsprintf(
           $conn,
           'JOIN %T %T ON %T.projectID = p.id AND %T.token LIKE %>',
           PhabricatorProject::TABLE_DATASOURCE_TOKEN,
           $token_table,
           $token_table,
           $token_table,
           $token);
       }
     }
 
     return $joins;
   }
 
   public function getQueryApplicationClass() {
     return 'PhabricatorProjectApplication';
   }
 
   protected function getPrimaryTableAlias() {
     return 'p';
   }
 
   private function linkProjectGraph(array $projects, array $ancestors) {
     $ancestor_map = mpull($ancestors, null, 'getPHID');
     $projects_map = mpull($projects, null, 'getPHID');
 
     $all_map = $projects_map + $ancestor_map;
 
     $done = array();
     foreach ($projects as $key => $project) {
       $seen = array($project->getPHID() => true);
 
       if (!$this->linkProject($project, $all_map, $done, $seen)) {
         $this->didRejectResult($project);
         unset($projects[$key]);
         continue;
       }
 
       foreach ($project->getAncestorProjects() as $ancestor) {
         $seen[$ancestor->getPHID()] = true;
       }
     }
 
     return $projects;
   }
 
   private function linkProject($project, array $all, array $done, array $seen) {
     $parent_phid = $project->getParentProjectPHID();
 
     // This project has no parent, so just attach `null` and return.
     if (!$parent_phid) {
       $project->attachParentProject(null);
       return true;
     }
 
     // This project has a parent, but it failed to load.
     if (empty($all[$parent_phid])) {
       return false;
     }
 
     // Test for graph cycles. If we encounter one, we're going to hide the
     // entire cycle since we can't meaningfully resolve it.
     if (isset($seen[$parent_phid])) {
       return false;
     }
 
     $seen[$parent_phid] = true;
 
     $parent = $all[$parent_phid];
     $project->attachParentProject($parent);
 
     if (!empty($done[$parent_phid])) {
       return true;
     }
 
     return $this->linkProject($parent, $all, $done, $seen);
   }
 
   private function getAllReachableAncestors(array $projects) {
     $ancestors = array();
 
     $seen = mpull($projects, null, 'getPHID');
 
     $stack = $projects;
     while ($stack) {
       $project = array_pop($stack);
 
       $phid = $project->getPHID();
       $ancestors[$phid] = $project;
 
       $parent_phid = $project->getParentProjectPHID();
       if (!$parent_phid) {
         continue;
       }
 
       if (isset($seen[$parent_phid])) {
         continue;
       }
 
       $seen[$parent_phid] = true;
       $stack[] = $project->getParentProject();
     }
 
     return $ancestors;
   }
 
   private function loadSlugs(array $projects) {
     // Build a map from primary slugs to projects.
     $primary_map = array();
     foreach ($projects as $project) {
       $primary_slug = $project->getPrimarySlug();
       if ($primary_slug === null) {
         continue;
       }
 
       $primary_map[$primary_slug] = $project;
     }
 
     // Link up all of the queried slugs which correspond to primary
     // slugs. If we can link up everything from this (no slugs were queried,
     // or only primary slugs were queried) we don't need to load anything
     // else.
     $unknown = $this->slugNormals;
     foreach ($unknown as $input => $normal) {
       if (isset($primary_map[$input])) {
         $match = $input;
       } else if (isset($primary_map[$normal])) {
         $match = $normal;
       } else {
         continue;
       }
 
       $this->slugMap[$input] = array(
         'slug' => $match,
         'projectPHID' => $primary_map[$match]->getPHID(),
       );
 
       unset($unknown[$input]);
     }
 
     // If we need slugs, we have to load everything.
     // If we still have some queried slugs which we haven't mapped, we only
     // need to look for them.
     // If we've mapped everything, we don't have to do any work.
     $project_phids = mpull($projects, 'getPHID');
     if ($this->needSlugs) {
       $slugs = id(new PhabricatorProjectSlug())->loadAllWhere(
         'projectPHID IN (%Ls)',
         $project_phids);
     } else if ($unknown) {
       $slugs = id(new PhabricatorProjectSlug())->loadAllWhere(
         'projectPHID IN (%Ls) AND slug IN (%Ls)',
         $project_phids,
         $unknown);
     } else {
       $slugs = array();
     }
 
     // Link up any slugs we were not able to link up earlier.
     $extra_map = mpull($slugs, 'getProjectPHID', 'getSlug');
     foreach ($unknown as $input => $normal) {
       if (isset($extra_map[$input])) {
         $match = $input;
       } else if (isset($extra_map[$normal])) {
         $match = $normal;
       } else {
         continue;
       }
 
       $this->slugMap[$input] = array(
         'slug' => $match,
         'projectPHID' => $extra_map[$match],
       );
 
       unset($unknown[$input]);
     }
 
     if ($this->needSlugs) {
       $slug_groups = mgroup($slugs, 'getProjectPHID');
       foreach ($projects as $project) {
         $project_slugs = idx($slug_groups, $project->getPHID(), array());
         $project->attachSlugs($project_slugs);
       }
     }
   }
 
 }
diff --git a/src/applications/project/storage/PhabricatorProject.php b/src/applications/project/storage/PhabricatorProject.php
index 81a5c09dc9..061886f6f0 100644
--- a/src/applications/project/storage/PhabricatorProject.php
+++ b/src/applications/project/storage/PhabricatorProject.php
@@ -1,758 +1,799 @@
 <?php
 
 final class PhabricatorProject extends PhabricatorProjectDAO
   implements
     PhabricatorApplicationTransactionInterface,
     PhabricatorFlaggableInterface,
     PhabricatorPolicyInterface,
     PhabricatorExtendedPolicyInterface,
     PhabricatorCustomFieldInterface,
     PhabricatorDestructibleInterface,
     PhabricatorFulltextInterface,
     PhabricatorConduitResultInterface,
     PhabricatorColumnProxyInterface {
 
   protected $name;
   protected $status = PhabricatorProjectStatus::STATUS_ACTIVE;
   protected $authorPHID;
   protected $primarySlug;
   protected $profileImagePHID;
   protected $icon;
   protected $color;
   protected $mailKey;
 
   protected $viewPolicy;
   protected $editPolicy;
   protected $joinPolicy;
   protected $isMembershipLocked;
 
   protected $parentProjectPHID;
   protected $hasWorkboard;
   protected $hasMilestones;
   protected $hasSubprojects;
   protected $milestoneNumber;
 
   protected $projectPath;
   protected $projectDepth;
   protected $projectPathKey;
 
   protected $properties = array();
 
   private $memberPHIDs = self::ATTACHABLE;
   private $watcherPHIDs = self::ATTACHABLE;
   private $sparseWatchers = self::ATTACHABLE;
   private $sparseMembers = self::ATTACHABLE;
   private $customFields = self::ATTACHABLE;
   private $profileImageFile = self::ATTACHABLE;
   private $slugs = self::ATTACHABLE;
   private $parentProject = self::ATTACHABLE;
 
   const TABLE_DATASOURCE_TOKEN = 'project_datasourcetoken';
 
   const PANEL_PROFILE = 'project.profile';
   const PANEL_POINTS = 'project.points';
   const PANEL_WORKBOARD = 'project.workboard';
   const PANEL_MEMBERS = 'project.members';
   const PANEL_MANAGE = 'project.manage';
   const PANEL_MILESTONES = 'project.milestones';
   const PANEL_SUBPROJECTS = 'project.subprojects';
 
   public static function initializeNewProject(PhabricatorUser $actor) {
     $app = id(new PhabricatorApplicationQuery())
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withClasses(array('PhabricatorProjectApplication'))
       ->executeOne();
 
     $view_policy = $app->getPolicy(
       ProjectDefaultViewCapability::CAPABILITY);
     $edit_policy = $app->getPolicy(
       ProjectDefaultEditCapability::CAPABILITY);
     $join_policy = $app->getPolicy(
       ProjectDefaultJoinCapability::CAPABILITY);
 
     $default_icon = PhabricatorProjectIconSet::getDefaultIconKey();
     $default_color = PhabricatorProjectIconSet::getDefaultColorKey();
 
     return id(new PhabricatorProject())
       ->setAuthorPHID($actor->getPHID())
       ->setIcon($default_icon)
       ->setColor($default_color)
       ->setViewPolicy($view_policy)
       ->setEditPolicy($edit_policy)
       ->setJoinPolicy($join_policy)
       ->setIsMembershipLocked(0)
       ->attachMemberPHIDs(array())
       ->attachSlugs(array())
       ->setHasWorkboard(0)
       ->setHasMilestones(0)
       ->setHasSubprojects(0)
       ->attachParentProject(null);
   }
 
   public function getCapabilities() {
     return array(
       PhabricatorPolicyCapability::CAN_VIEW,
       PhabricatorPolicyCapability::CAN_EDIT,
       PhabricatorPolicyCapability::CAN_JOIN,
     );
   }
 
   public function getPolicy($capability) {
     if ($this->isMilestone()) {
       return $this->getParentProject()->getPolicy($capability);
     }
 
     switch ($capability) {
       case PhabricatorPolicyCapability::CAN_VIEW:
         return $this->getViewPolicy();
       case PhabricatorPolicyCapability::CAN_EDIT:
         return $this->getEditPolicy();
       case PhabricatorPolicyCapability::CAN_JOIN:
         return $this->getJoinPolicy();
     }
   }
 
   public function hasAutomaticCapability($capability, PhabricatorUser $viewer) {
     if ($this->isMilestone()) {
       return $this->getParentProject()->hasAutomaticCapability(
         $capability,
         $viewer);
     }
 
     $can_edit = PhabricatorPolicyCapability::CAN_EDIT;
 
     switch ($capability) {
       case PhabricatorPolicyCapability::CAN_VIEW:
         if ($this->isUserMember($viewer->getPHID())) {
           // Project members can always view a project.
           return true;
         }
         break;
       case PhabricatorPolicyCapability::CAN_EDIT:
         $parent = $this->getParentProject();
         if ($parent) {
           $can_edit_parent = PhabricatorPolicyFilter::hasCapability(
             $viewer,
             $parent,
             $can_edit);
           if ($can_edit_parent) {
             return true;
           }
         }
         break;
       case PhabricatorPolicyCapability::CAN_JOIN:
         if (PhabricatorPolicyFilter::hasCapability($viewer, $this, $can_edit)) {
           // Project editors can always join a project.
           return true;
         }
         break;
     }
 
     return false;
   }
 
   public function describeAutomaticCapability($capability) {
 
     // TODO: Clarify the additional rules that parent and subprojects imply.
 
     switch ($capability) {
       case PhabricatorPolicyCapability::CAN_VIEW:
         return pht('Members of a project can always view it.');
       case PhabricatorPolicyCapability::CAN_JOIN:
         return pht('Users who can edit a project can always join it.');
     }
     return null;
   }
 
   public function getExtendedPolicy($capability, PhabricatorUser $viewer) {
     $extended = array();
 
     switch ($capability) {
       case PhabricatorPolicyCapability::CAN_VIEW:
         $parent = $this->getParentProject();
         if ($parent) {
           $extended[] = array(
             $parent,
             PhabricatorPolicyCapability::CAN_VIEW,
           );
         }
         break;
     }
 
     return $extended;
   }
 
   public function isUserMember($user_phid) {
     if ($this->memberPHIDs !== self::ATTACHABLE) {
       return in_array($user_phid, $this->memberPHIDs);
     }
     return $this->assertAttachedKey($this->sparseMembers, $user_phid);
   }
 
   public function setIsUserMember($user_phid, $is_member) {
     if ($this->sparseMembers === self::ATTACHABLE) {
       $this->sparseMembers = array();
     }
     $this->sparseMembers[$user_phid] = $is_member;
     return $this;
   }
 
   protected function getConfiguration() {
     return array(
       self::CONFIG_AUX_PHID => true,
       self::CONFIG_SERIALIZATION => array(
         'properties' => self::SERIALIZATION_JSON,
       ),
       self::CONFIG_COLUMN_SCHEMA => array(
         'name' => 'sort128',
         'status' => 'text32',
         'primarySlug' => 'text128?',
         'isMembershipLocked' => 'bool',
         'profileImagePHID' => 'phid?',
         'icon' => 'text32',
         'color' => 'text32',
         'mailKey' => 'bytes20',
         'joinPolicy' => 'policy',
         'parentProjectPHID' => 'phid?',
         'hasWorkboard' => 'bool',
         'hasMilestones' => 'bool',
         'hasSubprojects' => 'bool',
         'milestoneNumber' => 'uint32?',
         'projectPath' => 'hashpath64',
         'projectDepth' => 'uint32',
         'projectPathKey' => 'bytes4',
       ),
       self::CONFIG_KEY_SCHEMA => array(
         'key_icon' => array(
           'columns' => array('icon'),
         ),
         'key_color' => array(
           'columns' => array('color'),
         ),
         'key_milestone' => array(
           'columns' => array('parentProjectPHID', 'milestoneNumber'),
           'unique' => true,
         ),
         'key_primaryslug' => array(
           'columns' => array('primarySlug'),
           'unique' => true,
         ),
         'key_path' => array(
           'columns' => array('projectPath', 'projectDepth'),
         ),
         'key_pathkey' => array(
           'columns' => array('projectPathKey'),
           'unique' => true,
         ),
       ),
     ) + parent::getConfiguration();
   }
 
   public function generatePHID() {
     return PhabricatorPHID::generateNewPHID(
       PhabricatorProjectProjectPHIDType::TYPECONST);
   }
 
   public function attachMemberPHIDs(array $phids) {
     $this->memberPHIDs = $phids;
     return $this;
   }
 
   public function getMemberPHIDs() {
     return $this->assertAttached($this->memberPHIDs);
   }
 
   public function isArchived() {
     return ($this->getStatus() == PhabricatorProjectStatus::STATUS_ARCHIVED);
   }
 
   public function getProfileImageURI() {
     return $this->getProfileImageFile()->getBestURI();
   }
 
   public function attachProfileImageFile(PhabricatorFile $file) {
     $this->profileImageFile = $file;
     return $this;
   }
 
   public function getProfileImageFile() {
     return $this->assertAttached($this->profileImageFile);
   }
 
 
   public function isUserWatcher($user_phid) {
     if ($this->watcherPHIDs !== self::ATTACHABLE) {
       return in_array($user_phid, $this->watcherPHIDs);
     }
     return $this->assertAttachedKey($this->sparseWatchers, $user_phid);
   }
 
+  public function isUserAncestorWatcher($user_phid) {
+    $is_watcher = $this->isUserWatcher($user_phid);
+
+    if (!$is_watcher) {
+      $parent = $this->getParentProject();
+      if ($parent) {
+        return $parent->isUserWatcher($user_phid);
+      }
+    }
+
+    return $is_watcher;
+  }
+
+  public function getWatchedAncestorPHID($user_phid) {
+    if ($this->isUserWatcher($user_phid)) {
+      return $this->getPHID();
+    }
+
+    $parent = $this->getParentProject();
+    if ($parent) {
+      return $parent->getWatchedAncestorPHID($user_phid);
+    }
+
+    return null;
+  }
+
   public function setIsUserWatcher($user_phid, $is_watcher) {
     if ($this->sparseWatchers === self::ATTACHABLE) {
       $this->sparseWatchers = array();
     }
     $this->sparseWatchers[$user_phid] = $is_watcher;
     return $this;
   }
 
   public function attachWatcherPHIDs(array $phids) {
     $this->watcherPHIDs = $phids;
     return $this;
   }
 
   public function getWatcherPHIDs() {
     return $this->assertAttached($this->watcherPHIDs);
   }
 
+  public function getAllAncestorWatcherPHIDs() {
+    $parent = $this->getParentProject();
+    if ($parent) {
+      $watchers = $parent->getAllAncestorWatcherPHIDs();
+    } else {
+      $watchers = array();
+    }
+
+    foreach ($this->getWatcherPHIDs() as $phid) {
+      $watchers[$phid] = $phid;
+    }
+
+    return $watchers;
+  }
+
   public function attachSlugs(array $slugs) {
     $this->slugs = $slugs;
     return $this;
   }
 
   public function getSlugs() {
     return $this->assertAttached($this->slugs);
   }
 
   public function getColor() {
     if ($this->isArchived()) {
       return PHUITagView::COLOR_DISABLED;
     }
 
     return $this->color;
   }
 
   public function getURI() {
     $id = $this->getID();
     return "/project/view/{$id}/";
   }
 
   public function save() {
     if (!$this->getMailKey()) {
       $this->setMailKey(Filesystem::readRandomCharacters(20));
     }
 
     if (!strlen($this->getPHID())) {
       $this->setPHID($this->generatePHID());
     }
 
     if (!strlen($this->getProjectPathKey())) {
       $hash = PhabricatorHash::digestForIndex($this->getPHID());
       $hash = substr($hash, 0, 4);
       $this->setProjectPathKey($hash);
     }
 
     $path = array();
     $depth = 0;
     if ($this->parentProjectPHID) {
       $parent = $this->getParentProject();
       $path[] = $parent->getProjectPath();
       $depth = $parent->getProjectDepth() + 1;
     }
     $path[] = $this->getProjectPathKey();
     $path = implode('', $path);
 
     $limit = self::getProjectDepthLimit();
     if ($depth >= $limit) {
       throw new Exception(pht('Project depth is too great.'));
     }
 
     $this->setProjectPath($path);
     $this->setProjectDepth($depth);
 
     $this->openTransaction();
       $result = parent::save();
       $this->updateDatasourceTokens();
     $this->saveTransaction();
 
     return $result;
   }
 
   public static function getProjectDepthLimit() {
     // This is limited by how many path hashes we can fit in the path
     // column.
     return 16;
   }
 
   public function updateDatasourceTokens() {
     $table = self::TABLE_DATASOURCE_TOKEN;
     $conn_w = $this->establishConnection('w');
     $id = $this->getID();
 
     $slugs = queryfx_all(
       $conn_w,
       'SELECT * FROM %T WHERE projectPHID = %s',
       id(new PhabricatorProjectSlug())->getTableName(),
       $this->getPHID());
 
     $all_strings = ipull($slugs, 'slug');
     $all_strings[] = $this->getDisplayName();
     $all_strings = implode(' ', $all_strings);
 
     $tokens = PhabricatorTypeaheadDatasource::tokenizeString($all_strings);
 
     $sql = array();
     foreach ($tokens as $token) {
       $sql[] = qsprintf($conn_w, '(%d, %s)', $id, $token);
     }
 
     $this->openTransaction();
       queryfx(
         $conn_w,
         'DELETE FROM %T WHERE projectID = %d',
         $table,
         $id);
 
       foreach (PhabricatorLiskDAO::chunkSQL($sql) as $chunk) {
         queryfx(
           $conn_w,
           'INSERT INTO %T (projectID, token) VALUES %Q',
           $table,
           $chunk);
       }
     $this->saveTransaction();
   }
 
   public function isMilestone() {
     return ($this->getMilestoneNumber() !== null);
   }
 
   public function getParentProject() {
     return $this->assertAttached($this->parentProject);
   }
 
   public function attachParentProject(PhabricatorProject $project = null) {
     $this->parentProject = $project;
     return $this;
   }
 
   public function getAncestorProjectPaths() {
     $parts = array();
 
     $path = $this->getProjectPath();
     $parent_length = (strlen($path) - 4);
 
     for ($ii = $parent_length; $ii > 0; $ii -= 4) {
       $parts[] = substr($path, 0, $ii);
     }
 
     return $parts;
   }
 
   public function getAncestorProjects() {
     $ancestors = array();
 
     $cursor = $this->getParentProject();
     while ($cursor) {
       $ancestors[] = $cursor;
       $cursor = $cursor->getParentProject();
     }
 
     return $ancestors;
   }
 
   public function supportsEditMembers() {
     if ($this->isMilestone()) {
       return false;
     }
 
     if ($this->getHasSubprojects()) {
       return false;
     }
 
     return true;
   }
 
   public function supportsMilestones() {
     if ($this->isMilestone()) {
       return false;
     }
 
     return true;
   }
 
   public function supportsSubprojects() {
     if ($this->isMilestone()) {
       return false;
     }
 
     return true;
   }
 
   public function loadNextMilestoneNumber() {
     $current = queryfx_one(
       $this->establishConnection('w'),
       'SELECT MAX(milestoneNumber) n
         FROM %T
         WHERE parentProjectPHID = %s',
       $this->getTableName(),
       $this->getPHID());
 
     if (!$current) {
       $number = 1;
     } else {
       $number = (int)$current['n'] + 1;
     }
 
     return $number;
   }
 
   public function getDisplayName() {
     $name = $this->getName();
 
     // If this is a milestone, show it as "Parent > Sprint 99".
     if ($this->isMilestone()) {
       $name = pht(
         '%s (%s)',
         $this->getParentProject()->getName(),
         $name);
     }
 
     return $name;
   }
 
   public function getDisplayIconKey() {
     if ($this->isMilestone()) {
       $key = PhabricatorProjectIconSet::getMilestoneIconKey();
     } else {
       $key = $this->getIcon();
     }
 
     return $key;
   }
 
   public function getDisplayIconIcon() {
     $key = $this->getDisplayIconKey();
     return PhabricatorProjectIconSet::getIconIcon($key);
   }
 
   public function getDisplayIconName() {
     $key = $this->getDisplayIconKey();
     return PhabricatorProjectIconSet::getIconName($key);
   }
 
   public function getDisplayColor() {
     if ($this->isMilestone()) {
       return PhabricatorProjectIconSet::getDefaultColorKey();
     }
 
     return $this->getColor();
   }
 
   public function getDisplayIconComposeIcon() {
     $icon = $this->getDisplayIconIcon();
     return $icon;
   }
 
   public function getDisplayIconComposeColor() {
     $color = $this->getDisplayColor();
 
     $map = array(
       'grey' => 'charcoal',
       'checkered' => 'backdrop',
     );
 
     return idx($map, $color, $color);
   }
 
   public function getProperty($key, $default = null) {
     return idx($this->properties, $key, $default);
   }
 
   public function setProperty($key, $value) {
     $this->properties[$key] = $value;
     return $this;
   }
 
   public function getDefaultWorkboardSort() {
     return $this->getProperty('workboard.sort.default');
   }
 
   public function setDefaultWorkboardSort($sort) {
     return $this->setProperty('workboard.sort.default', $sort);
   }
 
   public function getDefaultWorkboardFilter() {
     return $this->getProperty('workboard.filter.default');
   }
 
   public function setDefaultWorkboardFilter($filter) {
     return $this->setProperty('workboard.filter.default', $filter);
   }
 
   public function getWorkboardBackgroundColor() {
     return $this->getProperty('workboard.background');
   }
 
   public function setWorkboardBackgroundColor($color) {
     return $this->setProperty('workboard.background', $color);
   }
 
   public function getDisplayWorkboardBackgroundColor() {
     $color = $this->getWorkboardBackgroundColor();
 
     if ($color === null) {
       $parent = $this->getParentProject();
       if ($parent) {
         return $parent->getDisplayWorkboardBackgroundColor();
       }
     }
 
     if ($color === 'none') {
       $color = null;
     }
 
     return $color;
   }
 
 
 /* -(  PhabricatorCustomFieldInterface  )------------------------------------ */
 
 
   public function getCustomFieldSpecificationForRole($role) {
     return PhabricatorEnv::getEnvConfig('projects.fields');
   }
 
   public function getCustomFieldBaseClass() {
     return 'PhabricatorProjectCustomField';
   }
 
   public function getCustomFields() {
     return $this->assertAttached($this->customFields);
   }
 
   public function attachCustomFields(PhabricatorCustomFieldAttachment $fields) {
     $this->customFields = $fields;
     return $this;
   }
 
 
 /* -(  PhabricatorApplicationTransactionInterface  )------------------------- */
 
 
   public function getApplicationTransactionEditor() {
     return new PhabricatorProjectTransactionEditor();
   }
 
   public function getApplicationTransactionObject() {
     return $this;
   }
 
   public function getApplicationTransactionTemplate() {
     return new PhabricatorProjectTransaction();
   }
 
   public function willRenderTimeline(
     PhabricatorApplicationTransactionView $timeline,
     AphrontRequest $request) {
 
     return $timeline;
   }
 
 
 /* -(  PhabricatorDestructibleInterface  )----------------------------------- */
 
 
   public function destroyObjectPermanently(
     PhabricatorDestructionEngine $engine) {
 
     $this->openTransaction();
       $this->delete();
 
       $columns = id(new PhabricatorProjectColumn())
         ->loadAllWhere('projectPHID = %s', $this->getPHID());
       foreach ($columns as $column) {
         $engine->destroyObject($column);
       }
 
       $slugs = id(new PhabricatorProjectSlug())
         ->loadAllWhere('projectPHID = %s', $this->getPHID());
       foreach ($slugs as $slug) {
         $slug->delete();
       }
 
     $this->saveTransaction();
   }
 
 
 /* -(  PhabricatorFulltextInterface  )--------------------------------------- */
 
 
   public function newFulltextEngine() {
     return new PhabricatorProjectFulltextEngine();
   }
 
 
 /* -(  PhabricatorConduitResultInterface  )---------------------------------- */
 
 
   public function getFieldSpecificationsForConduit() {
     return array(
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('name')
         ->setType('string')
         ->setDescription(pht('The name of the project.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('slug')
         ->setType('string')
         ->setDescription(pht('Primary slug/hashtag.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('icon')
         ->setType('map<string, wild>')
         ->setDescription(pht('Information about the project icon.')),
       id(new PhabricatorConduitSearchFieldSpecification())
         ->setKey('color')
         ->setType('map<string, wild>')
         ->setDescription(pht('Information about the project color.')),
     );
   }
 
   public function getFieldValuesForConduit() {
     $color_key = $this->getColor();
     $color_name = PhabricatorProjectIconSet::getColorName($color_key);
 
     return array(
       'name' => $this->getName(),
       'slug' => $this->getPrimarySlug(),
       'icon' => array(
         'key' => $this->getDisplayIconKey(),
         'name' => $this->getDisplayIconName(),
         'icon' => $this->getDisplayIconIcon(),
       ),
       'color' => array(
         'key' => $color_key,
         'name' => $color_name,
       ),
     );
   }
 
   public function getConduitSearchAttachments() {
     return array(
       id(new PhabricatorProjectsMembersSearchEngineAttachment())
         ->setAttachmentKey('members'),
       id(new PhabricatorProjectsWatchersSearchEngineAttachment())
         ->setAttachmentKey('watchers'),
     );
   }
 
 
 /* -(  PhabricatorColumnProxyInterface  )------------------------------------ */
 
 
   public function getProxyColumnName() {
     return $this->getName();
   }
 
   public function getProxyColumnIcon() {
     return $this->getDisplayIconIcon();
   }
 
   public function getProxyColumnClass() {
     if ($this->isMilestone()) {
       return 'phui-workboard-column-milestone';
     }
 
     return null;
   }
 
 
 }
diff --git a/src/applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php b/src/applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php
index ad089d8f3d..add833c127 100644
--- a/src/applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php
+++ b/src/applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php
@@ -1,124 +1,110 @@
 <?php
 
 final class PhabricatorSubscriptionsEditController
   extends PhabricatorController {
 
   public function handleRequest(AphrontRequest $request) {
     $viewer = $request->getViewer();
     $phid = $request->getURIData('phid');
     $action = $request->getURIData('action');
 
     if (!$request->isFormPost()) {
       return new Aphront400Response();
     }
 
     switch ($action) {
       case 'add':
         $is_add = true;
         break;
       case 'delete':
         $is_add = false;
         break;
       default:
         return new Aphront400Response();
     }
 
     $handle = id(new PhabricatorHandleQuery())
       ->setViewer($viewer)
       ->withPHIDs(array($phid))
       ->executeOne();
 
-    if (phid_get_type($phid) == PhabricatorProjectProjectPHIDType::TYPECONST) {
-      // TODO: This is a big hack, but a weak argument for adding some kind
-      // of "load for role" feature to ObjectQuery, and also not a really great
-      // argument for adding some kind of "load extra stuff" feature to
-      // SubscriberInterface. Do this for now and wait for the best way forward
-      // to become more clear?
-
-      $object = id(new PhabricatorProjectQuery())
-        ->setViewer($viewer)
-        ->withPHIDs(array($phid))
-        ->needWatchers(true)
-        ->executeOne();
-    } else {
-      $object = id(new PhabricatorObjectQuery())
-        ->setViewer($viewer)
-        ->withPHIDs(array($phid))
-        ->executeOne();
-    }
+    $object = id(new PhabricatorObjectQuery())
+      ->setViewer($viewer)
+      ->withPHIDs(array($phid))
+      ->executeOne();
 
     if (!($object instanceof PhabricatorSubscribableInterface)) {
       return $this->buildErrorResponse(
         pht('Bad Object'),
         pht('This object is not subscribable.'),
         $handle->getURI());
     }
 
     if ($object->isAutomaticallySubscribed($viewer->getPHID())) {
       return $this->buildErrorResponse(
         pht('Automatically Subscribed'),
         pht('You are automatically subscribed to this object.'),
         $handle->getURI());
     }
 
     if ($object instanceof PhabricatorApplicationTransactionInterface) {
       if ($is_add) {
         $xaction_value = array(
           '+' => array($viewer->getPHID()),
         );
       } else {
         $xaction_value = array(
           '-' => array($viewer->getPHID()),
         );
       }
 
       $xaction = id($object->getApplicationTransactionTemplate())
         ->setTransactionType(PhabricatorTransactions::TYPE_SUBSCRIBERS)
         ->setNewValue($xaction_value);
 
       $editor = id($object->getApplicationTransactionEditor())
         ->setActor($viewer)
         ->setContinueOnNoEffect(true)
         ->setContinueOnMissingFields(true)
         ->setContentSourceFromRequest($request);
 
       $editor->applyTransactions(
         $object->getApplicationTransactionObject(),
         array($xaction));
     } else {
 
       // TODO: Eventually, get rid of this once everything implements
       // PhabriatorApplicationTransactionInterface.
 
       $editor = id(new PhabricatorSubscriptionsEditor())
         ->setActor($viewer)
         ->setObject($object);
 
       if ($is_add) {
         $editor->subscribeExplicit(array($viewer->getPHID()), $explicit = true);
       } else {
         $editor->unsubscribe(array($viewer->getPHID()));
       }
 
       $editor->save();
     }
 
     // TODO: We should just render the "Unsubscribe" action and swap it out
     // in the document for Ajax requests.
     return id(new AphrontReloadResponse())->setURI($handle->getURI());
   }
 
   private function buildErrorResponse($title, $message, $uri) {
     $request = $this->getRequest();
     $viewer = $request->getUser();
 
     $dialog = id(new AphrontDialogView())
       ->setUser($viewer)
       ->setTitle($title)
       ->appendChild($message)
       ->addCancelButton($uri);
 
     return id(new AphrontDialogResponse())->setDialog($dialog);
   }
 
 }
diff --git a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
index d6f70cac39..cbfaebb182 100644
--- a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
+++ b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
@@ -1,3480 +1,3485 @@
 <?php
 
 /**
  *
  * Publishing and Managing State
  * ======
  *
  * After applying changes, the Editor queues a worker to publish mail, feed,
  * and notifications, and to perform other background work like updating search
  * indexes. This allows it to do this work without impacting performance for
  * users.
  *
  * When work is moved to the daemons, the Editor state is serialized by
  * @{method:getWorkerState}, then reloaded in a daemon process by
  * @{method:loadWorkerState}. **This is fragile.**
  *
  * State is not persisted into the daemons by default, because we can not send
  * arbitrary objects into the queue. This means the default behavior of any
  * state properties is to reset to their defaults without warning prior to
  * publishing.
  *
  * The easiest way to avoid this is to keep Editors stateless: the overwhelming
  * majority of Editors can be written statelessly. If you need to maintain
  * state, you can either:
  *
  *   - not require state to exist during publishing; or
  *   - pass state to the daemons by implementing @{method:getCustomWorkerState}
  *     and @{method:loadCustomWorkerState}.
  *
  * This architecture isn't ideal, and we may eventually split this class into
  * "Editor" and "Publisher" parts to make it more robust. See T6367 for some
  * discussion and context.
  *
  * @task mail Sending Mail
  * @task feed Publishing Feed Stories
  * @task search Search Index
  * @task files Integration with Files
  * @task workers Managing Workers
  */
 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 $unmentionablePHIDMap = array();
   private $applicationEmail;
 
   private $isPreview;
   private $isHeraldEditor;
   private $isInverseEdgeEditor;
   private $actingAsPHID;
   private $disableEmail;
 
   private $heraldEmailPHIDs = array();
   private $heraldForcedEmailPHIDs = array();
   private $heraldHeader;
   private $mailToPHIDs = array();
   private $mailCCPHIDs = array();
   private $feedNotifyPHIDs = array();
   private $feedRelatedPHIDs = array();
 
   const STORAGE_ENCODING_BINARY = 'binary';
 
   /**
    * Get the class name for the application this editor is a part of.
    *
    * Uninstalling the application will disable the editor.
    *
    * @return string Editor's application class name.
    */
   abstract public function getEditorApplicationClass();
 
 
   /**
    * Get a description of the objects this editor edits, like "Differential
    * Revisions".
    *
    * @return string Human readable description of edited objects.
    */
   abstract public function getEditorObjectsDescription();
 
 
   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 setIsInverseEdgeEditor($is_inverse_edge_editor) {
     $this->isInverseEdgeEditor = $is_inverse_edge_editor;
     return $this;
   }
 
   public function getIsInverseEdgeEditor() {
     return $this->isInverseEdgeEditor;
   }
 
   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 setUnmentionablePHIDMap(array $map) {
     $this->unmentionablePHIDMap = $map;
     return $this;
   }
 
   public function getUnmentionablePHIDMap() {
     return $this->unmentionablePHIDMap;
   }
 
   protected function shouldEnableMentions(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return true;
   }
 
   public function setApplicationEmail(
     PhabricatorMetaMTAApplicationEmail $email) {
     $this->applicationEmail = $email;
     return $this;
   }
 
   public function getApplicationEmail() {
     return $this->applicationEmail;
   }
 
   public function getTransactionTypesForObject($object) {
     $old = $this->object;
     try {
       $this->object = $object;
       $result = $this->getTransactionTypes();
       $this->object = $old;
     } catch (Exception $ex) {
       $this->object = $old;
       throw $ex;
     }
     return $result;
   }
 
   public function getTransactionTypes() {
     $types = array();
 
     $types[] = PhabricatorTransactions::TYPE_CREATE;
 
     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;
     }
 
     if ($this->object instanceof PhabricatorTokenReceiverInterface) {
       $types[] = PhabricatorTransactions::TYPE_TOKEN;
     }
 
     if ($this->object instanceof PhabricatorProjectInterface ||
         $this->object instanceof PhabricatorMentionableInterface) {
       $types[] = PhabricatorTransactions::TYPE_EDGE;
     }
 
     if ($this->object instanceof PhabricatorSpacesInterface) {
       $types[] = PhabricatorTransactions::TYPE_SPACE;
     }
 
     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_CREATE:
         return null;
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return array_values($this->subscribers);
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         if ($this->getIsNewObject()) {
           return null;
         }
         return $object->getViewPolicy();
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         if ($this->getIsNewObject()) {
           return null;
         }
         return $object->getEditPolicy();
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         if ($this->getIsNewObject()) {
           return null;
         }
         return $object->getJoinPolicy();
       case PhabricatorTransactions::TYPE_SPACE:
         if ($this->getIsNewObject()) {
           return null;
         }
 
         $space_phid = $object->getSpacePHID();
         if ($space_phid === null) {
           $default_space = PhabricatorSpacesNamespaceQuery::getDefaultSpace();
           if ($default_space) {
             $space_phid = $default_space->getPHID();
           }
         }
 
         return $space_phid;
       case PhabricatorTransactions::TYPE_EDGE:
         $edge_type = $xaction->getMetadataValue('edge:type');
         if (!$edge_type) {
           throw new Exception(
             pht(
               "Edge transaction has no '%s'!",
               '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_CREATE:
         return null;
       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:
       case PhabricatorTransactions::TYPE_TOKEN:
       case PhabricatorTransactions::TYPE_INLINESTATE:
         return $xaction->getNewValue();
       case PhabricatorTransactions::TYPE_SPACE:
         $space_phid = $xaction->getNewValue();
         if (!strlen($space_phid)) {
           // If an install has no Spaces or the Spaces controls are not visible
           // to the viewer, we might end up with the empty string here instead
           // of a strict `null`, because some controller just used `getStr()`
           // to read the space PHID from the request.
           // Just make this work like callers might reasonably expect so we
           // don't need to handle this specially in every EditController.
           return $this->getActor()->getDefaultSpacePHID();
         } else {
           return $space_phid;
         }
       case PhabricatorTransactions::TYPE_EDGE:
         $new_value = $this->getEdgeTransactionNewValue($xaction);
 
         $edge_type = $xaction->getMetadataValue('edge:type');
         $type_project = PhabricatorProjectObjectHasProjectEdgeType::EDGECONST;
         if ($edge_type == $type_project) {
           $new_value = $this->applyProjectConflictRules($new_value);
         }
 
         return $new_value;
       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(pht('Capability not supported!'));
   }
 
   protected function getCustomTransactionNewValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     throw new Exception(pht('Capability not supported!'));
   }
 
   protected function transactionHasEffect(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CREATE:
         return true;
       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 PhutilMethodNotImplementedException();
   }
 
   private function applyInternalEffects(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->applyApplicationTransactionInternalEffects($xaction);
       case PhabricatorTransactions::TYPE_CREATE:
       case PhabricatorTransactions::TYPE_BUILDABLE:
       case PhabricatorTransactions::TYPE_TOKEN:
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
       case PhabricatorTransactions::TYPE_INLINESTATE:
       case PhabricatorTransactions::TYPE_EDGE:
       case PhabricatorTransactions::TYPE_SPACE:
       case PhabricatorTransactions::TYPE_COMMENT:
         return $this->applyBuiltinInternalTransaction($object, $xaction);
     }
 
     return $this->applyCustomInternalTransaction($object, $xaction);
   }
 
   private function applyExternalEffects(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     switch ($xaction->getTransactionType()) {
       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;
         return $this->applyBuiltinExternalTransaction($object, $xaction);
 
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->applyApplicationTransactionExternalEffects($xaction);
       case PhabricatorTransactions::TYPE_CREATE:
       case PhabricatorTransactions::TYPE_EDGE:
       case PhabricatorTransactions::TYPE_BUILDABLE:
       case PhabricatorTransactions::TYPE_TOKEN:
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
       case PhabricatorTransactions::TYPE_INLINESTATE:
       case PhabricatorTransactions::TYPE_SPACE:
       case PhabricatorTransactions::TYPE_COMMENT:
         return $this->applyBuiltinExternalTransaction($object, $xaction);
     }
 
     return $this->applyCustomExternalTransaction($object, $xaction);
   }
 
   protected function applyCustomInternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     $type = $xaction->getTransactionType();
     throw new Exception(
       pht(
         "Transaction type '%s' is missing an internal apply implementation!",
         $type));
   }
 
   protected function applyCustomExternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     $type = $xaction->getTransactionType();
     throw new Exception(
       pht(
         "Transaction type '%s' is missing an external apply implementation!",
         $type));
   }
 
   /**
    * @{class:PhabricatorTransactions} provides many built-in transactions
    * which should not require much - if any - code in specific applications.
    *
    * This method is a hook for the exceedingly-rare cases where you may need
    * to do **additional** work for built-in transactions. Developers should
    * extend this method, making sure to return the parent implementation
    * regardless of handling any transactions.
    *
    * See also @{method:applyBuiltinExternalTransaction}.
    */
   protected function applyBuiltinInternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         $object->setViewPolicy($xaction->getNewValue());
         break;
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         $object->setEditPolicy($xaction->getNewValue());
         break;
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         $object->setJoinPolicy($xaction->getNewValue());
         break;
       case PhabricatorTransactions::TYPE_SPACE:
         $object->setSpacePHID($xaction->getNewValue());
         break;
     }
   }
 
   /**
    * See @{method::applyBuiltinInternalTransaction}.
    */
   protected function applyBuiltinExternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_EDGE:
         if ($this->getIsInverseEdgeEditor()) {
           // If we're writing an inverse edge transaction, don't actually
           // do anything. The initiating editor on the other side of the
           // transaction will take care of the edge writes.
           break;
         }
 
         $old = $xaction->getOldValue();
         $new = $xaction->getNewValue();
         $src = $object->getPHID();
         $const = $xaction->getMetadataValue('edge:type');
 
         $type = PhabricatorEdgeType::getByConstant($const);
         if ($type->shouldWriteInverseTransactions()) {
           $this->applyInverseEdgeTransactions(
             $object,
             $xaction,
             $type->getInverseEdgeConstant());
         }
 
         foreach ($new as $dst_phid => $edge) {
           $new[$dst_phid]['src'] = $src;
         }
 
         $editor = new PhabricatorEdgeEditor();
 
         foreach ($old as $dst_phid => $edge) {
           if (!empty($new[$dst_phid])) {
             if ($old[$dst_phid]['data'] === $new[$dst_phid]['data']) {
               continue;
             }
           }
           $editor->removeEdge($src, $const, $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, $const, $dst_phid, $data);
         }
 
         $editor->save();
         break;
     }
   }
 
   /**
    * 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 {
       $xaction->setEditPolicy($this->getActingAsPHID());
     }
 
     $xaction->setAuthorPHID($this->getActingAsPHID());
     $xaction->setContentSource($this->getContentSource());
     $xaction->attachViewer($actor);
     $xaction->attachObject($object);
 
     if ($object->getPHID()) {
       $xaction->setObjectPHID($object->getPHID());
     }
 
     return $xaction;
   }
 
   protected function didApplyInternalEffects(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return $xactions;
   }
 
   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[] = $this->validateAllTransactions($object, $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);
       }
 
       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);
     }
 
     try {
       $xactions = $this->filterTransactions($object, $xactions);
     } catch (Exception $ex) {
       if ($read_locking) {
         $object->endReadLocking();
       }
       if ($transaction_open) {
         $object->killTransaction();
       }
       throw $ex;
     }
 
     // TODO: Once everything is on EditEngine, just use getIsNewObject() to
     // figure this out instead.
     $mark_as_create = false;
     $create_type = PhabricatorTransactions::TYPE_CREATE;
     foreach ($xactions as $xaction) {
       if ($xaction->getTransactionType() == $create_type) {
         $mark_as_create = true;
       }
     }
 
     if ($mark_as_create) {
       foreach ($xactions as $xaction) {
         $xaction->setIsCreateTransaction(true);
       }
     }
 
     // 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);
     $file_phids = $this->extractFilePHIDs($object, $xactions);
 
     if ($is_preview) {
       $this->loadHandles($xactions);
       return $xactions;
     }
 
     $comment_editor = id(new PhabricatorApplicationTransactionCommentEditor())
       ->setActor($actor)
       ->setActingAsPHID($this->getActingAsPHID())
       ->setContentSource($this->getContentSource());
 
     if (!$transaction_open) {
       $object->openTransaction();
     }
 
       foreach ($xactions as $xaction) {
         $this->applyInternalEffects($object, $xaction);
       }
 
       $xactions = $this->didApplyInternalEffects($object, $xactions);
 
       try {
         $object->save();
       } catch (AphrontDuplicateKeyQueryException $ex) {
         $object->killTransaction();
 
         // This callback has an opportunity to throw a better exception,
         // so execution may end here.
         $this->didCatchDuplicateKeyException($object, $xactions, $ex);
 
         throw $ex;
       }
 
       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->getIsInverseEdgeEditor()) {
       // If we're applying inverse edge transactions, don't trigger Herald.
       // From a product perspective, the current set of inverse edges (most
       // often, mentions) aren't things users would expect to trigger Herald.
       // From a technical perspective, objects loaded by the inverse editor may
       // not have enough data to execute rules. At least for now, just stop
       // Herald from executing when applying inverse edges.
     } 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 PhabricatorHeraldApplication())->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);
       }
 
       // If Herald did not generate transactions, we may still need to handle
       // "Send an Email" rules.
       $adapter = $this->getHeraldAdapter();
       $this->heraldEmailPHIDs = $adapter->getEmailPHIDs();
       $this->heraldForcedEmailPHIDs = $adapter->getForcedEmailPHIDs();
     }
 
     $this->didApplyTransactions($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 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);
     }
 
     $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());
     }
     $this->heraldHeader = $herald_header;
 
     // We're going to compute some of the data we'll use to publish these
     // transactions here, before queueing a worker.
     //
     // Primarily, this is more correct: we want to publish the object as it
     // exists right now. The worker may not execute for some time, and we want
     // to use the current To/CC list, not respect any changes which may occur
     // between now and when the worker executes.
     //
     // As a secondary benefit, this tends to reduce the amount of state that
     // Editors need to pass into workers.
     $object = $this->willPublish($object, $xactions);
 
     if (!$this->getDisableEmail()) {
       if ($this->shouldSendMail($object, $xactions)) {
         $this->mailToPHIDs = $this->getMailTo($object);
         $this->mailCCPHIDs = $this->getMailCC($object);
       }
     }
 
     if ($this->shouldPublishFeedStory($object, $xactions)) {
       $this->feedRelatedPHIDs = $this->getFeedRelatedPHIDs($object, $xactions);
       $this->feedNotifyPHIDs = $this->getFeedNotifyPHIDs($object, $xactions);
     }
 
     PhabricatorWorker::scheduleTask(
       'PhabricatorApplicationTransactionPublishWorker',
       array(
         'objectPHID' => $object->getPHID(),
         'actorPHID' => $this->getActingAsPHID(),
         'xactionPHIDs' => mpull($xactions, 'getPHID'),
         'state' => $this->getWorkerState(),
       ),
       array(
         'objectPHID' => $object->getPHID(),
         'priority' => PhabricatorWorker::PRIORITY_ALERTS,
       ));
 
     return $xactions;
   }
 
   protected function didCatchDuplicateKeyException(
     PhabricatorLiskDAO $object,
     array $xactions,
     Exception $ex) {
     return;
   }
 
   public function publishTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     // Hook for edges or other properties that may need (re-)loading
     $object = $this->willPublish($object, $xactions);
 
     $messages = array();
     if (!$this->getDisableEmail()) {
       if ($this->shouldSendMail($object, $xactions)) {
         $messages = $this->buildMail($object, $xactions);
       }
     }
 
     if ($this->supportsSearch()) {
       PhabricatorSearchWorker::queueDocumentForIndexing(
         $object->getPHID(),
         array(
           'transactionPHIDs' => mpull($xactions, 'getPHID'),
         ));
     }
 
     if ($this->shouldPublishFeedStory($object, $xactions)) {
 
       $mailed = array();
       foreach ($messages as $mail) {
         foreach ($mail->buildRecipientList() as $phid) {
           $mailed[$phid] = $phid;
         }
       }
 
       $this->publishFeedStory($object, $xactions, $mailed);
     }
 
     // NOTE: This actually sends the mail. We do this last to reduce the chance
     // that we send some mail, hit an exception, then send the mail again when
     // retrying.
     foreach ($messages as $mail) {
       $mail->save();
     }
 
     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 PhutilInvalidStateException('setContentSource');
     }
 
     // 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(
           $xaction,
           pht(
             'You can not apply transactions which already have %s!',
             'objectPHIDs'));
       }
       if ($xaction->getAuthorPHID()) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             'You can not apply transactions which already have %s!',
             'authorPHIDs'));
       }
       if ($xaction->getCommentPHID()) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             'You can not apply transactions which already have %s!',
             'commentPHIDs'));
       }
       if ($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 %s set, but it does not!',
             'oldValue'));
       }
 
       if ($has_value && !$expect_value) {
         throw new PhabricatorApplicationTransactionStructureException(
           $xaction,
           pht(
             'This transaction should generate its %s automatically, '.
             'but has already had one set!',
             'oldValue'));
       }
 
       $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:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
       case PhabricatorTransactions::TYPE_SPACE:
         PhabricatorPolicyFilter::requireCapability(
           $actor,
           $object,
           PhabricatorPolicyCapability::CAN_EDIT);
         break;
     }
   }
 
   private function buildSubscribeTransaction(
     PhabricatorLiskDAO $object,
     array $xactions,
     array $blocks) {
 
     if (!($object instanceof PhabricatorSubscribableInterface)) {
       return null;
     }
 
     if ($this->shouldEnableMentions($object, $xactions)) {
       $texts = array_mergev($blocks);
       $phids = PhabricatorMarkupEngine::extractPHIDsFromMentions(
         $this->getActor(),
         $texts);
     } else {
       $phids = array();
     }
 
     $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);
     }
 
     if ($phids) {
       $users = id(new PhabricatorPeopleQuery())
         ->setViewer($this->getActor())
         ->withPHIDs($phids)
         ->execute();
       $users = mpull($users, null, 'getPHID');
 
       foreach ($phids as $key => $phid) {
         // Do not subscribe mentioned users
         // who do not have VIEW Permissions
         if ($object instanceof PhabricatorPolicyInterface
           && !PhabricatorPolicyFilter::hasCapability(
           $users[$phid],
           $object,
           PhabricatorPolicyCapability::CAN_VIEW)
         ) {
           unset($phids[$key]);
         } else {
           if ($object->isAutomaticallySubscribed($phid)) {
             unset($phids[$key]);
           }
         }
       }
       $phids = array_values($phids);
     }
     // No else here to properly return null should we unset all subscriber
     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.
    */
   protected 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);
   }
 
 
   public function getExpandedSupportTransactions(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     $xactions = array($xaction);
     $xactions = $this->expandSupportTransactions(
       $object,
       $xactions);
 
     if (count($xactions) == 1) {
       return array();
     }
 
     foreach ($xactions as $index => $cxaction) {
       if ($cxaction === $xaction) {
         unset($xactions[$index]);
         break;
       }
     }
 
     return $xactions;
   }
 
   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);
     }
 
     $subscribe_xaction = $this->buildSubscribeTransaction(
       $object,
       $xactions,
       $blocks);
     if ($subscribe_xaction) {
       $xactions[] = $subscribe_xaction;
     }
 
     // TODO: For now, this is just a placeholder.
     $engine = PhabricatorMarkupEngine::getEngine('extract');
     $engine->setConfig('viewer', $this->requireActor());
 
     $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) {
 
     $block_xactions = $this->expandCustomRemarkupBlockTransactions(
       $object,
       $xactions,
       $blocks,
       $engine);
 
     $mentioned_phids = array();
     if ($this->shouldEnableMentions($object, $xactions)) {
       foreach ($blocks as $key => $xaction_blocks) {
         foreach ($xaction_blocks as $block) {
           $engine->markupText($block);
           $mentioned_phids += $engine->getTextMetadata(
             PhabricatorObjectRemarkupRule::KEY_MENTIONED_OBJECTS,
             array());
         }
       }
     }
 
     if (!$mentioned_phids) {
       return $block_xactions;
     }
 
     $mentioned_objects = id(new PhabricatorObjectQuery())
       ->setViewer($this->getActor())
       ->withPHIDs($mentioned_phids)
       ->execute();
 
     $mentionable_phids = array();
     if ($this->shouldEnableMentions($object, $xactions)) {
       foreach ($mentioned_objects as $mentioned_object) {
         if ($mentioned_object instanceof PhabricatorMentionableInterface) {
           $mentioned_phid = $mentioned_object->getPHID();
           if (idx($this->getUnmentionablePHIDMap(), $mentioned_phid)) {
             continue;
           }
           // don't let objects mention themselves
           if ($object->getPHID() && $mentioned_phid == $object->getPHID()) {
             continue;
           }
           $mentionable_phids[$mentioned_phid] = $mentioned_phid;
         }
       }
     }
 
     if ($mentionable_phids) {
       $edge_type = PhabricatorObjectMentionsObjectEdgeType::EDGECONST;
       $block_xactions[] = newv(get_class(head($xactions)), array())
         ->setIgnoreOnNoEffect(true)
         ->setTransactionType(PhabricatorTransactions::TYPE_EDGE)
         ->setMetadataValue('edge:type', $edge_type)
         ->setNewValue(array('+' => $mentionable_phids));
     }
 
     return $block_xactions;
   }
 
   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 = null) {
 
     if ($old !== null) {
       $old = array_fuse($old);
     } else {
       $old = array_fuse($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(
         pht(
           "Invalid '%s' value for PHID transaction. Value should contain only ".
           "keys '%s' (add PHIDs), '%s' (remove PHIDs) and '%s' (set PHIDS).",
           'new',
           '+',
           '-',
           '='));
     }
 
     $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(
         pht(
           "Invalid '%s' value for Edge transaction. Value should contain only ".
           "keys '%s' (add edges), '%s' (remove edges) and '%s' (set edges).",
           'new',
           '+',
           '-',
           '='));
     }
 
     $old = $xaction->getOldValue();
 
     $lists = array($new_set, $new_add, $new_rem);
     foreach ($lists as $list) {
       $this->checkEdgeList($list, $xaction->getMetadataValue('edge:type'));
     }
 
     $result = array();
     foreach ($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, $edge_type) {
     if (!$list) {
       return;
     }
     foreach ($list as $key => $item) {
       if (phid_get_type($key) === PhabricatorPHIDConstants::PHID_TYPE_UNKNOWN) {
         throw new Exception(
           pht(
             'Edge transactions must have destination PHIDs as in edge '.
             'lists (found key "%s" on transaction of type "%s").',
             $key,
             $edge_type));
       }
       if (!is_array($item) && $item !== $key) {
         throw new Exception(
           pht(
             'Edge transactions must have PHIDs or edge specs as values '.
             '(found value "%s" on transaction of type "%s").',
             $item,
             $edge_type));
       }
     }
   }
 
   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(
           pht(
             "Edge transaction includes edge of type '%s', but ".
             "transaction is of type '%s'. Each edge transaction ".
             "must alter edges of only one type.",
             $this_type,
             $edge_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->hasComment()) {
         $xaction->setTransactionType($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_SPACE:
         $errors[] = $this->validateSpaceTransactions(
           $object,
           $xactions,
           $type);
         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;
   }
 
 
   private function validateSpaceTransactions(
     PhabricatorLiskDAO $object,
     array $xactions,
     $transaction_type) {
     $errors = array();
 
     $actor = $this->getActor();
 
     $has_spaces = PhabricatorSpacesNamespaceQuery::getViewerSpacesExist($actor);
     $actor_spaces = PhabricatorSpacesNamespaceQuery::getViewerSpaces($actor);
     $active_spaces = PhabricatorSpacesNamespaceQuery::getViewerActiveSpaces(
       $actor);
     foreach ($xactions as $xaction) {
       $space_phid = $xaction->getNewValue();
 
       if ($space_phid === null) {
         if (!$has_spaces) {
           // The install doesn't have any spaces, so this is fine.
           continue;
         }
 
         // The install has some spaces, so every object needs to be put
         // in a valid space.
         $errors[] = new PhabricatorApplicationTransactionValidationError(
           $transaction_type,
           pht('Invalid'),
           pht('You must choose a space for this object.'),
           $xaction);
         continue;
       }
 
       // If the PHID isn't `null`, it needs to be a valid space that the
       // viewer can see.
       if (empty($actor_spaces[$space_phid])) {
         $errors[] = new PhabricatorApplicationTransactionValidationError(
           $transaction_type,
           pht('Invalid'),
           pht(
             'You can not shift this object in the selected space, because '.
             'the space does not exist or you do not have access to it.'),
           $xaction);
       } else if (empty($active_spaces[$space_phid])) {
 
         // It's OK to edit objects in an archived space, so just move on if
         // we aren't adjusting the value.
         $old_space_phid = $this->getTransactionOldValue($object, $xaction);
         if ($space_phid == $old_space_phid) {
           continue;
         }
 
         $errors[] = new PhabricatorApplicationTransactionValidationError(
           $transaction_type,
           pht('Archived'),
           pht(
             'You can not shift this object into the selected space, because '.
             'the space is archived. Objects can not be created inside (or '.
             'moved into) archived spaces.'),
           $xaction);
       }
     }
 
     return $errors;
   }
 
 
   protected function adjustObjectForPolicyChecks(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $copy = clone $object;
 
     foreach ($xactions as $xaction) {
       switch ($xaction->getTransactionType()) {
         case PhabricatorTransactions::TYPE_SUBSCRIBERS:
           $clone_xaction = clone $xaction;
           $clone_xaction->setOldValue(array_values($this->subscribers));
           $clone_xaction->setNewValue(
             $this->getPHIDTransactionNewValue(
               $clone_xaction));
 
           PhabricatorPolicyRule::passTransactionHintToRule(
             $copy,
             new PhabricatorSubscriptionsSubscribersPolicyRule(),
             array_fuse($clone_xaction->getNewValue()));
 
           break;
         case PhabricatorTransactions::TYPE_SPACE:
           $space_phid = $this->getTransactionNewValue($object, $xaction);
           $copy->setSpacePHID($space_phid);
           break;
       }
     }
 
     return $copy;
   }
 
   protected function validateAllTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return array();
   }
 
   /**
    * 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;
   }
 
   /**
    * Check that text field input isn't longer than a specified length.
    *
    * A text field input is invalid if the length of the input is longer than a
    * specified length. This length can be determined by the space allotted in
    * the database, or given arbitrarily.
    * This method is intended to make implementing @{method:validateTransaction}
    * more convenient:
    *
    *   $overdrawn = $this->validateIsTextFieldTooLong(
    *     $object->getName(),
    *     $xactions,
    *     $field_length);
    *
    * This will return `true` if the net effect of the object and transactions
    * is a field that is too long.
    *
    * @param wild Current field value.
    * @param list<PhabricatorApplicationTransaction> Transactions editing the
    *          field.
    * @param integer for maximum field length.
    * @return bool True if the field will be too long after edits.
    */
   protected function validateIsTextFieldTooLong(
     $field_value,
     array $xactions,
     $length) {
 
     if ($xactions) {
       $new_value_length = phutil_utf8_strlen(last($xactions)->getNewValue());
       if ($new_value_length <= $length) {
         return false;
       } else {
         return true;
       }
     }
 
     $old_value_length = phutil_utf8_strlen($field_value);
     if ($old_value_length <= $length) {
       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->getActingAsPHID();
 
     $type_user = PhabricatorPeopleUserPHIDType::TYPECONST;
     if (phid_get_type($actor_phid) != $type_user) {
       // Transactions by application actors like Herald, Harbormaster and
       // Diffusion should not CC the applications.
       return $xactions;
     }
 
     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(),
         PhabricatorObjectHasUnsubscriberEdgeType::EDGECONST);
       $unsub = array_fuse($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
    */
   private function buildMail(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $email_to = $this->mailToPHIDs;
     $email_cc = $this->mailCCPHIDs;
     $email_cc = array_merge($email_cc, $this->heraldEmailPHIDs);
 
     $targets = $this->buildReplyHandler($object)
       ->getMailTargets($email_to, $email_cc);
 
     // Set this explicitly before we start swapping out the effective actor.
     $this->setActingAsPHID($this->getActingAsPHID());
 
     $messages = array();
     foreach ($targets as $target) {
       $original_actor = $this->getActor();
 
       $viewer = $target->getViewer();
       $this->setActor($viewer);
       $locale = PhabricatorEnv::beginScopedLocale($viewer->getTranslation());
 
       $caught = null;
       $mail = null;
       try {
         // Reload handles for the new viewer.
         $this->loadHandles($xactions);
 
         $mail = $this->buildMailForTarget($object, $xactions, $target);
       } catch (Exception $ex) {
         $caught = $ex;
       }
 
       $this->setActor($original_actor);
       unset($locale);
 
       if ($caught) {
         throw $ex;
       }
 
       if ($mail) {
         $messages[] = $mail;
       }
     }
 
     $this->runHeraldMailRules($messages);
 
     return $messages;
   }
 
   private function buildMailForTarget(
     PhabricatorLiskDAO $object,
     array $xactions,
     PhabricatorMailTarget $target) {
 
     // Check if any of the transactions are visible for this viewer. If we
     // don't have any visible transactions, don't send the mail.
 
     $any_visible = false;
     foreach ($xactions as $xaction) {
       if (!$xaction->shouldHideForMail($xactions)) {
         $any_visible = true;
         break;
       }
     }
 
     if (!$any_visible) {
       return null;
     }
 
     $mail = $this->buildMailTemplate($object);
     $body = $this->buildMailBody($object, $xactions);
 
     $mail_tags = $this->getMailTags($object, $xactions);
     $action = $this->getMailAction($object, $xactions);
 
     if (PhabricatorEnv::getEnvConfig('metamta.email-preferences')) {
       $this->addEmailPreferenceSectionToMailBody(
         $body,
         $object,
         $xactions);
     }
 
     $mail
       ->setSensitiveContent(false)
       ->setFrom($this->getActingAsPHID())
       ->setSubjectPrefix($this->getMailSubjectPrefix())
       ->setVarySubjectPrefix('['.$action.']')
       ->setThreadID($this->getMailThreadID($object), $this->getIsNewObject())
       ->setRelatedPHID($object->getPHID())
       ->setExcludeMailRecipientPHIDs($this->getExcludeMailRecipientPHIDs())
       ->setForceHeraldMailRecipientPHIDs($this->heraldForcedEmailPHIDs)
       ->setMailTags($mail_tags)
       ->setIsBulk(true)
       ->setBody($body->render())
       ->setHTMLBody($body->renderHTML());
 
     foreach ($body->getAttachments() as $attachment) {
       $mail->addAttachment($attachment);
     }
 
     if ($this->heraldHeader) {
       $mail->addHeader('X-Herald-Rules', $this->heraldHeader);
     }
 
     if ($object instanceof PhabricatorProjectInterface) {
       $this->addMailProjectMetadata($object, $mail);
     }
 
     if ($this->getParentMessageID()) {
       $mail->setParentMessageID($this->getParentMessageID());
     }
 
     return $target->willSendMail($mail);
   }
 
   private function addMailProjectMetadata(
     PhabricatorLiskDAO $object,
     PhabricatorMetaMTAMail $template) {
 
     $project_phids = PhabricatorEdgeQuery::loadDestinationPHIDs(
       $object->getPHID(),
       PhabricatorProjectObjectHasProjectEdgeType::EDGECONST);
 
     if (!$project_phids) {
       return;
     }
 
     // TODO: This viewer isn't quite right. It would be slightly better to use
     // the mail recipient, but that's not very easy given the way rendering
     // works today.
 
     $handles = id(new PhabricatorHandleQuery())
       ->setViewer($this->requireActor())
       ->withPHIDs($project_phids)
       ->execute();
 
     $project_tags = array();
     foreach ($handles as $handle) {
       if (!$handle->isComplete()) {
         continue;
       }
       $project_tags[] = '<'.$handle->getObjectName().'>';
     }
 
     if (!$project_tags) {
       return;
     }
 
     $project_tags = implode(', ', $project_tags);
     $template->addHeader('X-Phabricator-Projects', $project_tags);
   }
 
 
   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(pht('Capability not supported.'));
   }
 
   /**
    * @task mail
    */
   protected function getMailSubjectPrefix() {
     throw new Exception(pht('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
    */
   public function getMailTagsMap() {
     // TODO: We should move shared mail tags, like "comment", here.
     return array();
   }
 
 
   /**
    * @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(pht('Capability not supported.'));
   }
 
 
   /**
    * @task mail
    */
   protected function getMailTo(PhabricatorLiskDAO $object) {
     throw new Exception(pht('Capability not supported.'));
   }
 
 
   /**
    * @task mail
    */
   protected function getMailCC(PhabricatorLiskDAO $object) {
     $phids = array();
     $has_support = false;
 
     if ($object instanceof PhabricatorSubscribableInterface) {
       $phid = $object->getPHID();
       $phids[] = PhabricatorSubscribersQuery::loadSubscribersForPHID($phid);
       $has_support = true;
     }
 
     if ($object instanceof PhabricatorProjectInterface) {
       $project_phids = PhabricatorEdgeQuery::loadDestinationPHIDs(
         $object->getPHID(),
         PhabricatorProjectObjectHasProjectEdgeType::EDGECONST);
 
       if ($project_phids) {
-        $watcher_type = PhabricatorObjectHasWatcherEdgeType::EDGECONST;
-
-        $query = id(new PhabricatorEdgeQuery())
-          ->withSourcePHIDs($project_phids)
-          ->withEdgeTypes(array($watcher_type));
-        $query->execute();
+        $projects = id(new PhabricatorProjectQuery())
+          ->setViewer(PhabricatorUser::getOmnipotentUser())
+          ->withPHIDs($project_phids)
+          ->needWatchers(true)
+          ->execute();
+
+        $watcher_phids = array();
+        foreach ($projects as $project) {
+          foreach ($project->getAllAncestorWatcherPHIDs() as $phid) {
+            $watcher_phids[$phid] = $phid;
+          }
+        }
 
-        $watcher_phids = $query->getDestinationPHIDs();
         if ($watcher_phids) {
           // We need to do a visibility check for all the watchers, as
           // watching a project is not a guarantee that you can see objects
           // associated with it.
           $users = id(new PhabricatorPeopleQuery())
             ->setViewer($this->requireActor())
             ->withPHIDs($watcher_phids)
             ->execute();
 
           $watchers = array();
           foreach ($users as $user) {
             $can_see = PhabricatorPolicyFilter::hasCapability(
               $user,
               $object,
               PhabricatorPolicyCapability::CAN_VIEW);
             if ($can_see) {
               $watchers[] = $user->getPHID();
             }
           }
           $phids[] = $watchers;
         }
       }
 
       $has_support = true;
     }
 
     if (!$has_support) {
       throw new Exception(pht('Capability not supported.'));
     }
 
     return array_mergev($phids);
   }
 
 
   /**
    * @task mail
    */
   protected function buildMailBody(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $body = new PhabricatorMetaMTAMailBody();
     $body->setViewer($this->requireActor());
 
     $this->addHeadersAndCommentsToMailBody($body, $xactions);
     $this->addCustomFieldsToMailBody($body, $object, $xactions);
     return $body;
   }
 
 
   /**
    * @task mail
    */
   protected function addEmailPreferenceSectionToMailBody(
     PhabricatorMetaMTAMailBody $body,
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $href = PhabricatorEnv::getProductionURI(
       '/settings/panel/emailpreferences/');
     $body->addLinkSection(pht('EMAIL PREFERENCES'), $href);
   }
 
 
   /**
    * @task mail
    */
   protected function addHeadersAndCommentsToMailBody(
     PhabricatorMetaMTAMailBody $body,
     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->addRawSection(implode("\n", $headers));
 
     foreach ($comments as $comment) {
       $body->addRemarkupSection(null, $comment);
     }
   }
 
   /**
    * @task mail
    */
   protected function addCustomFieldsToMailBody(
     PhabricatorMetaMTAMailBody $body,
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     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);
       }
     }
   }
 
 
   /**
    * @task mail
    */
   private function runHeraldMailRules(array $messages) {
     foreach ($messages as $message) {
       $engine = new HeraldEngine();
       $adapter = id(new PhabricatorMailOutboundMailHeraldAdapter())
         ->setObject($message);
 
       $rules = $engine->loadRulesForAdapter($adapter);
       $effects = $engine->applyRules($rules, $adapter);
       $engine->applyEffects($effects, $adapter, $rules);
     }
   }
 
 
 /* -(  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) {
 
     $phids = array(
       $object->getPHID(),
       $this->getActingAsPHID(),
     );
 
     if ($object instanceof PhabricatorProjectInterface) {
       $project_phids = PhabricatorEdgeQuery::loadDestinationPHIDs(
         $object->getPHID(),
         PhabricatorProjectObjectHasProjectEdgeType::EDGECONST);
       foreach ($project_phids as $project_phid) {
         $phids[] = $project_phid;
       }
     }
 
     return $phids;
   }
 
 
   /**
    * @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);
 
     if (!$xactions) {
       return;
     }
 
     $related_phids = $this->feedRelatedPHIDs;
     $subscribed_phids = $this->feedNotifyPHIDs;
 
     $story_type = $this->getFeedStoryType();
     $story_data = $this->getFeedStoryData($object, $xactions);
 
     id(new PhabricatorFeedStoryPublisher())
       ->setStoryType($story_type)
       ->setStoryData($story_data)
       ->setStoryTime(time())
       ->setStoryAuthorPHID($this->getActingAsPHID())
       ->setRelatedPHIDs($related_phids)
       ->setPrimaryObjectPHID($object->getPHID())
       ->setSubscribedPHIDs($subscribed_phids)
       ->setMailRecipientPHIDs($mailed_phids)
       ->setMailTags($this->getMailTags($object, $xactions))
       ->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(pht('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, $xactions)
       ->setContentSource($this->getContentSource())
       ->setIsNewObject($this->getIsNewObject())
       ->setAppliedTransactions($xactions);
 
     if ($this->getApplicationEmail()) {
       $adapter->setApplicationEmail($this->getApplicationEmail());
     }
 
     $xscript = HeraldEngine::loadAndApplyRules($adapter);
 
     $this->setHeraldAdapter($adapter);
     $this->setHeraldTranscript($xscript);
 
     if ($adapter instanceof HarbormasterBuildableAdapterInterface) {
       HarbormasterBuildable::applyBuildPlans(
         $adapter->getHarbormasterBuildablePHID(),
         $adapter->getHarbormasterContainerPHID(),
         $adapter->getQueuedHarbormasterBuildRequests());
     }
 
     return array_merge(
       $this->didApplyHeraldRules($object, $adapter, $xscript),
       $adapter->getQueuedTransactions());
   }
 
   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(
         pht(
         "Custom field transaction has no '%s'!",
         'customfield:key'));
     }
 
     $field = PhabricatorCustomField::getObjectField(
       $object,
       PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS,
       $field_key);
 
     if (!$field) {
       throw new Exception(
         pht(
           "Custom field transaction has invalid '%s'; field '%s' ".
           "is disabled or does not exist.",
           'customfield:key',
           $field_key));
     }
 
     if (!$field->shouldAppearInApplicationTransactions()) {
       throw new Exception(
         pht(
           "Custom field transaction '%s' does not implement ".
           "integration for %s.",
           $field_key,
           '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(
         $this->getActor(),
         $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 = new PhabricatorEdgeEditor();
 
     $src = $object->getPHID();
     $type = PhabricatorObjectHasFileEdgeType::EDGECONST;
     foreach ($file_phids as $dst) {
       $editor->addEdge($src, $type, $dst);
     }
 
     $editor->save();
   }
 
   private function applyInverseEdgeTransactions(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction,
     $inverse_type) {
 
     $old = $xaction->getOldValue();
     $new = $xaction->getNewValue();
 
     $add = array_keys(array_diff_key($new, $old));
     $rem = array_keys(array_diff_key($old, $new));
 
     $add = array_fuse($add);
     $rem = array_fuse($rem);
     $all = $add + $rem;
 
     $nodes = id(new PhabricatorObjectQuery())
       ->setViewer($this->requireActor())
       ->withPHIDs($all)
       ->execute();
 
     foreach ($nodes as $node) {
       if (!($node instanceof PhabricatorApplicationTransactionInterface)) {
         continue;
       }
 
       if ($node instanceof PhabricatorUser) {
         // TODO: At least for now, don't record inverse edge transactions
         // for users (for example, "alincoln joined project X"): Feed fills
         // this role instead.
         continue;
       }
 
       $editor = $node->getApplicationTransactionEditor();
       $template = $node->getApplicationTransactionTemplate();
       $target = $node->getApplicationTransactionObject();
 
       if (isset($add[$node->getPHID()])) {
         $edge_edit_type = '+';
       } else {
         $edge_edit_type = '-';
       }
 
       $template
         ->setTransactionType($xaction->getTransactionType())
         ->setMetadataValue('edge:type', $inverse_type)
         ->setNewValue(
           array(
             $edge_edit_type => array($object->getPHID() => $object->getPHID()),
           ));
 
       $editor
         ->setContinueOnNoEffect(true)
         ->setContinueOnMissingFields(true)
         ->setParentMessageID($this->getParentMessageID())
         ->setIsInverseEdgeEditor(true)
         ->setActor($this->requireActor())
         ->setActingAsPHID($this->getActingAsPHID())
         ->setContentSource($this->getContentSource());
 
       $editor->applyTransactions($target, array($template));
     }
   }
 
 
 /* -(  Workers  )------------------------------------------------------------ */
 
 
   /**
    * Load any object state which is required to publish transactions.
    *
    * This hook is invoked in the main process before we compute data related
    * to publishing transactions (like email "To" and "CC" lists), and again in
    * the worker before publishing occurs.
    *
    * @return object Publishable object.
    * @task workers
    */
   protected function willPublish(PhabricatorLiskDAO $object, array $xactions) {
     return $object;
   }
 
 
   /**
    * Convert the editor state to a serializable dictionary which can be passed
    * to a worker.
    *
    * This data will be loaded with @{method:loadWorkerState} in the worker.
    *
    * @return dict<string, wild> Serializable editor state.
    * @task workers
    */
   final private function getWorkerState() {
     $state = array();
     foreach ($this->getAutomaticStateProperties() as $property) {
       $state[$property] = $this->$property;
     }
 
     $custom_state = $this->getCustomWorkerState();
     $custom_encoding = $this->getCustomWorkerStateEncoding();
 
     $state += array(
       'excludeMailRecipientPHIDs' => $this->getExcludeMailRecipientPHIDs(),
       'custom' => $this->encodeStateForStorage($custom_state, $custom_encoding),
       'custom.encoding' => $custom_encoding,
     );
 
     return $state;
   }
 
 
   /**
    * Hook; return custom properties which need to be passed to workers.
    *
    * @return dict<string, wild> Custom properties.
    * @task workers
    */
   protected function getCustomWorkerState() {
     return array();
   }
 
 
   /**
    * Hook; return storage encoding for custom properties which need to be
    * passed to workers.
    *
    * This primarily allows binary data to be passed to workers and survive
    * JSON encoding.
    *
    * @return dict<string, string> Property encodings.
    * @task workers
    */
   protected function getCustomWorkerStateEncoding() {
     return array();
   }
 
 
   /**
    * Load editor state using a dictionary emitted by @{method:getWorkerState}.
    *
    * This method is used to load state when running worker operations.
    *
    * @param dict<string, wild> Editor state, from @{method:getWorkerState}.
    * @return this
    * @task workers
    */
   final public function loadWorkerState(array $state) {
     foreach ($this->getAutomaticStateProperties() as $property) {
       $this->$property = idx($state, $property);
     }
 
     $exclude = idx($state, 'excludeMailRecipientPHIDs', array());
     $this->setExcludeMailRecipientPHIDs($exclude);
 
     $custom_state = idx($state, 'custom', array());
     $custom_encodings = idx($state, 'custom.encoding', array());
     $custom = $this->decodeStateFromStorage($custom_state, $custom_encodings);
 
     $this->loadCustomWorkerState($custom);
 
     return $this;
   }
 
 
   /**
    * Hook; set custom properties on the editor from data emitted by
    * @{method:getCustomWorkerState}.
    *
    * @param dict<string, wild> Custom state,
    *   from @{method:getCustomWorkerState}.
    * @return this
    * @task workers
    */
   protected function loadCustomWorkerState(array $state) {
     return $this;
   }
 
 
   /**
    * Get a list of object properties which should be automatically sent to
    * workers in the state data.
    *
    * These properties will be automatically stored and loaded by the editor in
    * the worker.
    *
    * @return list<string> List of properties.
    * @task workers
    */
   private function getAutomaticStateProperties() {
     return array(
       'parentMessageID',
       'disableEmail',
       'isNewObject',
       'heraldEmailPHIDs',
       'heraldForcedEmailPHIDs',
       'heraldHeader',
       'mailToPHIDs',
       'mailCCPHIDs',
       'feedNotifyPHIDs',
       'feedRelatedPHIDs',
     );
   }
 
   /**
    * Apply encodings prior to storage.
    *
    * See @{method:getCustomWorkerStateEncoding}.
    *
    * @param map<string, wild> Map of values to encode.
    * @param map<string, string> Map of encodings to apply.
    * @return map<string, wild> Map of encoded values.
    * @task workers
    */
   final private function encodeStateForStorage(
     array $state,
     array $encodings) {
 
     foreach ($state as $key => $value) {
       $encoding = idx($encodings, $key);
       switch ($encoding) {
         case self::STORAGE_ENCODING_BINARY:
           // The mechanics of this encoding (serialize + base64) are a little
           // awkward, but it allows us encode arrays and still be JSON-safe
           // with binary data.
 
           $value = @serialize($value);
           if ($value === false) {
             throw new Exception(
               pht(
                 'Failed to serialize() value for key "%s".',
                 $key));
           }
 
           $value = base64_encode($value);
           if ($value === false) {
             throw new Exception(
               pht(
                 'Failed to base64 encode value for key "%s".',
                 $key));
           }
           break;
       }
       $state[$key] = $value;
     }
 
     return $state;
   }
 
 
   /**
    * Undo storage encoding applied when storing state.
    *
    * See @{method:getCustomWorkerStateEncoding}.
    *
    * @param map<string, wild> Map of encoded values.
    * @param map<string, string> Map of encodings.
    * @return map<string, wild> Map of decoded values.
    * @task workers
    */
   final private function decodeStateFromStorage(
     array $state,
     array $encodings) {
 
     foreach ($state as $key => $value) {
       $encoding = idx($encodings, $key);
       switch ($encoding) {
         case self::STORAGE_ENCODING_BINARY:
           $value = base64_decode($value);
           if ($value === false) {
             throw new Exception(
               pht(
                 'Failed to base64_decode() value for key "%s".',
                 $key));
           }
 
           $value = unserialize($value);
           break;
       }
       $state[$key] = $value;
     }
 
     return $state;
   }
 
 
   /**
    * Remove conflicts from a list of projects.
    *
    * Objects aren't allowed to be tagged with multiple milestones in the same
    * group, nor projects such that one tag is the ancestor of any other tag.
    * If the list of PHIDs include mutually exclusive projects, remove the
    * conflicting projects.
    *
    * @param list<phid> List of project PHIDs.
    * @return list<phid> List with conflicts removed.
    */
   private function applyProjectConflictRules(array $phids) {
     if (!$phids) {
       return array();
     }
 
     // Overall, the last project in the list wins in cases of conflict (so when
     // you add something, the thing you just added sticks and removes older
     // values).
 
     // Beyond that, there are two basic cases:
 
     // Milestones: An object can't be in "A > Sprint 3" and "A > Sprint 4".
     // If multiple projects are milestones of the same parent, we only keep the
     // last one.
 
     // Ancestor: You can't be in "A" and "A > B". If "A > B" comes later
     // in the list, we remove "A" and keep "A > B". If "A" comes later, we
     // remove "A > B" and keep "A".
 
     // Note that it's OK to be in "A > B" and "A > C". There's only a conflict
     // if one project is an ancestor of another. It's OK to have something
     // tagged with multiple projects which share a common ancestor, so long as
     // they are not mutual ancestors.
 
     $viewer = PhabricatorUser::getOmnipotentUser();
 
     $projects = id(new PhabricatorProjectQuery())
       ->setViewer($viewer)
       ->withPHIDs(array_keys($phids))
       ->execute();
     $projects = mpull($projects, null, 'getPHID');
 
     // We're going to build a map from each project with milestones to the last
     // milestone in the list. This last milestone is the milestone we'll keep.
     $milestone_map = array();
 
     // We're going to build a set of the projects which have no descendants
     // later in the list. This allows us to apply both ancestor rules.
     $ancestor_map = array();
 
     foreach ($phids as $phid => $ignored) {
       $project = idx($projects, $phid);
       if (!$project) {
         continue;
       }
 
       // This is the last milestone we've seen, so set it as the selection for
       // the project's parent. This might be setting a new value or overwriting
       // an earlier value.
       if ($project->isMilestone()) {
         $parent_phid = $project->getParentProjectPHID();
         $milestone_map[$parent_phid] = $phid;
       }
 
       // Since this is the last item in the list we've examined so far, add it
       // to the set of projects with no later descendants.
       $ancestor_map[$phid] = $phid;
 
       // Remove any ancestors from the set, since this is a later descendant.
       foreach ($project->getAncestorProjects() as $ancestor) {
         $ancestor_phid = $ancestor->getPHID();
         unset($ancestor_map[$ancestor_phid]);
       }
     }
 
     // Now that we've built the maps, we can throw away all the projects which
     // have conflicts.
     foreach ($phids as $phid => $ignored) {
       $project = idx($projects, $phid);
 
       if (!$project) {
         // If a PHID is invalid, we just leave it as-is. We could clean it up,
         // but leaving it untouched is less likely to cause collateral damage.
         continue;
       }
 
       // If this was a milestone, check if it was the last milestone from its
       // group in the list. If not, remove it from the list.
       if ($project->isMilestone()) {
         $parent_phid = $project->getParentProjectPHID();
         if ($milestone_map[$parent_phid] !== $phid) {
           unset($phids[$phid]);
           continue;
         }
       }
 
       // If a later project in the list is a subproject of this one, it will
       // have removed ancestors from the map. If this project does not point
       // at itself in the ancestor map, it should be discarded in favor of a
       // subproject that comes later.
       if (idx($ancestor_map, $phid) !== $phid) {
         unset($phids[$phid]);
         continue;
       }
 
       // If a later project in the list is an ancestor of this one, it will
       // have added itself to the map. If any ancestor of this project points
       // at itself in the map, this project should be dicarded in favor of
       // that later ancestor.
       foreach ($project->getAncestorProjects() as $ancestor) {
         $ancestor_phid = $ancestor->getPHID();
         if (isset($ancestor_map[$ancestor_phid])) {
           unset($phids[$phid]);
           continue 2;
         }
       }
     }
 
     return $phids;
   }
 
 }