diff --git a/src/applications/maniphest/editor/ManiphestTransactionEditor.php b/src/applications/maniphest/editor/ManiphestTransactionEditor.php
index a899192006..5225f5ea06 100644
--- a/src/applications/maniphest/editor/ManiphestTransactionEditor.php
+++ b/src/applications/maniphest/editor/ManiphestTransactionEditor.php
@@ -1,374 +1,434 @@
 <?php
 
 final class ManiphestTransactionEditor
   extends PhabricatorApplicationTransactionEditor {
 
   public function getTransactionTypes() {
     $types = parent::getTransactionTypes();
 
     $types[] = PhabricatorTransactions::TYPE_COMMENT;
     $types[] = ManiphestTransaction::TYPE_PRIORITY;
     $types[] = ManiphestTransaction::TYPE_STATUS;
     $types[] = ManiphestTransaction::TYPE_TITLE;
     $types[] = ManiphestTransaction::TYPE_DESCRIPTION;
     $types[] = ManiphestTransaction::TYPE_OWNER;
     $types[] = ManiphestTransaction::TYPE_CCS;
     $types[] = ManiphestTransaction::TYPE_PROJECTS;
     $types[] = ManiphestTransaction::TYPE_ATTACH;
     $types[] = ManiphestTransaction::TYPE_EDGE;
     $types[] = ManiphestTransaction::TYPE_SUBPRIORITY;
+    $types[] = ManiphestTransaction::TYPE_PROJECT_COLUMN;
     $types[] = PhabricatorTransactions::TYPE_VIEW_POLICY;
     $types[] = PhabricatorTransactions::TYPE_EDIT_POLICY;
 
     return $types;
   }
 
   protected function getCustomTransactionOldValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case ManiphestTransaction::TYPE_PRIORITY:
         if ($this->getIsNewObject()) {
           return null;
         }
         return (int)$object->getPriority();
       case ManiphestTransaction::TYPE_STATUS:
         if ($this->getIsNewObject()) {
           return null;
         }
         return (int)$object->getStatus();
       case ManiphestTransaction::TYPE_TITLE:
         if ($this->getIsNewObject()) {
           return null;
         }
         return $object->getTitle();
       case ManiphestTransaction::TYPE_DESCRIPTION:
         if ($this->getIsNewObject()) {
           return null;
         }
         return $object->getDescription();
       case ManiphestTransaction::TYPE_OWNER:
         return nonempty($object->getOwnerPHID(), null);
       case ManiphestTransaction::TYPE_CCS:
         return array_values(array_unique($object->getCCPHIDs()));
       case ManiphestTransaction::TYPE_PROJECTS:
         return array_values(array_unique($object->getProjectPHIDs()));
       case ManiphestTransaction::TYPE_ATTACH:
         return $object->getAttached();
       case ManiphestTransaction::TYPE_EDGE:
+      case ManiphestTransaction::TYPE_PROJECT_COLUMN:
         // These are pre-populated.
         return $xaction->getOldValue();
       case ManiphestTransaction::TYPE_SUBPRIORITY:
         return $object->getSubpriority();
     }
 
   }
 
   protected function getCustomTransactionNewValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case ManiphestTransaction::TYPE_PRIORITY:
       case ManiphestTransaction::TYPE_STATUS:
         return (int)$xaction->getNewValue();
       case ManiphestTransaction::TYPE_CCS:
       case ManiphestTransaction::TYPE_PROJECTS:
         return array_values(array_unique($xaction->getNewValue()));
       case ManiphestTransaction::TYPE_OWNER:
         return nonempty($xaction->getNewValue(), null);
       case ManiphestTransaction::TYPE_TITLE:
       case ManiphestTransaction::TYPE_DESCRIPTION:
       case ManiphestTransaction::TYPE_ATTACH:
       case ManiphestTransaction::TYPE_EDGE:
       case ManiphestTransaction::TYPE_SUBPRIORITY:
+      case ManiphestTransaction::TYPE_PROJECT_COLUMN:
         return $xaction->getNewValue();
     }
   }
 
 
   protected function transactionHasEffect(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     $old = $xaction->getOldValue();
     $new = $xaction->getNewValue();
 
     switch ($xaction->getTransactionType()) {
       case ManiphestTransaction::TYPE_PROJECTS:
       case ManiphestTransaction::TYPE_CCS:
         sort($old);
         sort($new);
         return ($old !== $new);
+      case ManiphestTransaction::TYPE_PROJECT_COLUMN:
+        $new_column_phids = $new['columnPHIDs'];
+        $old_column_phids = $old['columnPHIDs'];
+        sort($new_column_phids);
+        sort($old_column_phids);
+        return ($old !== $new);
     }
 
     return parent::transactionHasEffect($object, $xaction);
   }
 
   protected function applyCustomInternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case ManiphestTransaction::TYPE_PRIORITY:
         return $object->setPriority($xaction->getNewValue());
       case ManiphestTransaction::TYPE_STATUS:
         return $object->setStatus($xaction->getNewValue());
       case ManiphestTransaction::TYPE_TITLE:
         return $object->setTitle($xaction->getNewValue());
       case ManiphestTransaction::TYPE_DESCRIPTION:
         return $object->setDescription($xaction->getNewValue());
       case ManiphestTransaction::TYPE_OWNER:
         $phid = $xaction->getNewValue();
 
         // Update the "ownerOrdering" column to contain the full name of the
         // owner, if the task is assigned.
 
         $handle = null;
         if ($phid) {
           $handle = id(new PhabricatorHandleQuery())
             ->setViewer($this->getActor())
             ->withPHIDs(array($phid))
             ->executeOne();
         }
 
         if ($handle) {
           $object->setOwnerOrdering($handle->getName());
         } else {
           $object->setOwnerOrdering(null);
         }
 
         return $object->setOwnerPHID($phid);
       case ManiphestTransaction::TYPE_CCS:
         return $object->setCCPHIDs($xaction->getNewValue());
       case ManiphestTransaction::TYPE_PROJECTS:
         return $object->setProjectPHIDs($xaction->getNewValue());
       case ManiphestTransaction::TYPE_ATTACH:
         return $object->setAttached($xaction->getNewValue());
       case ManiphestTransaction::TYPE_EDGE:
         // These are a weird, funky mess and are already being applied by the
         // time we reach this.
         return;
       case ManiphestTransaction::TYPE_SUBPRIORITY:
         $data = $xaction->getNewValue();
         $new_sub = $this->getNextSubpriority(
           $data['newPriority'],
           $data['newSubpriorityBase']);
         $object->setSubpriority($new_sub);
         return;
+      case ManiphestTransaction::TYPE_PROJECT_COLUMN:
+        // these do external (edge) updates
+        return;
     }
 
   }
 
   protected function expandTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     $xactions = parent::expandTransaction($object, $xaction);
     switch ($xaction->getTransactionType()) {
       case ManiphestTransaction::TYPE_SUBPRIORITY:
         $data = $xaction->getNewValue();
         $new_pri = $data['newPriority'];
         if ($new_pri != $object->getPriority()) {
           $xactions[] = id(new ManiphestTransaction())
             ->setTransactionType(ManiphestTransaction::TYPE_PRIORITY)
             ->setNewValue($new_pri);
         }
         break;
       default:
         break;
     }
 
     return $xactions;
   }
 
   protected function applyCustomExternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
+
+    switch ($xaction->getTransactionType()) {
+      case ManiphestTransaction::TYPE_PROJECT_COLUMN:
+        $new = $xaction->getNewValue();
+        $old = $xaction->getOldValue();
+        $src = $object->getPHID();
+        $dst = head($new['columnPHIDs']);
+        $edges = $old['columnPHIDs'];
+        $edge_type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_COLUMN;
+        // NOTE: Normally, we expect only one edge to exist, but this works in
+        // a general way so it will repair any stray edges.
+        $remove = array();
+        $edge_missing = true;
+        foreach ($edges as $phid) {
+          if ($phid == $dst) {
+            $edge_missing = false;
+          } else {
+            $remove[] = $phid;
+          }
+        }
+
+        $add = array();
+        if ($edge_missing) {
+          $add[] = $dst;
+        }
+
+        // This should never happen because of the code in
+        // transactionHasEffect, but keep it for maximum conservativeness
+        if (!$add && !$remove) {
+          return;
+        }
+
+        $editor = id(new PhabricatorEdgeEditor())
+          ->setActor($this->getActor())
+          ->setSuppressEvents(true);
+
+        foreach ($add as $phid) {
+          $editor->addEdge($src, $edge_type, $phid);
+        }
+        foreach ($remove as $phid) {
+          $editor->removeEdge($src, $edge_type, $phid);
+        }
+        $editor->save();
+        break;
+      default:
+        break;
+    }
   }
 
   protected function shouldSendMail(
     PhabricatorLiskDAO $object,
     array $xactions) {
+
     $should_mail = true;
     if (count($xactions) == 1) {
       $xaction = head($xactions);
       switch ($xaction->getTransactionType()) {
         case ManiphestTransaction::TYPE_SUBPRIORITY:
           $should_mail = false;
           break;
         default:
           $should_mail = true;
           break;
       }
     }
     return $should_mail;
   }
 
   protected function getMailSubjectPrefix() {
     return PhabricatorEnv::getEnvConfig('metamta.maniphest.subject-prefix');
   }
 
   protected function getMailThreadID(PhabricatorLiskDAO $object) {
     return 'maniphest-task-'.$object->getPHID();
   }
 
   protected function getMailTo(PhabricatorLiskDAO $object) {
     return array(
       $object->getOwnerPHID(),
       $this->requireActor()->getPHID(),
     );
   }
 
   protected function getMailCC(PhabricatorLiskDAO $object) {
     return $object->getCCPHIDs();
   }
 
   protected function buildReplyHandler(PhabricatorLiskDAO $object) {
     return id(new ManiphestReplyHandler())
       ->setMailReceiver($object);
   }
 
   protected function buildMailTemplate(PhabricatorLiskDAO $object) {
     $id = $object->getID();
     $title = $object->getTitle();
 
     return id(new PhabricatorMetaMTAMail())
       ->setSubject("T{$id}: {$title}")
       ->addHeader('Thread-Topic', "T{$id}: ".$object->getOriginalTitle());
   }
 
   protected function buildMailBody(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $body = parent::buildMailBody($object, $xactions);
 
     if ($this->getIsNewObject()) {
       $body->addTextSection(
         pht('TASK DESCRIPTION'),
         $object->getDescription());
     }
 
     $body->addTextSection(
       pht('TASK DETAIL'),
       PhabricatorEnv::getProductionURI('/T'.$object->getID()));
 
     return $body;
   }
 
   protected function supportsFeed() {
     return true;
   }
 
   protected function supportsSearch() {
     return true;
   }
 
   protected function supportsHerald() {
     return true;
   }
 
   protected function buildHeraldAdapter(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     return id(new HeraldManiphestTaskAdapter())
       ->setTask($object);
   }
 
   protected function didApplyHeraldRules(
     PhabricatorLiskDAO $object,
     HeraldAdapter $adapter,
     HeraldTranscript $transcript) {
 
     $save_again = false;
     $cc_phids = $adapter->getCcPHIDs();
     if ($cc_phids) {
       $existing_cc = $object->getCCPHIDs();
       $new_cc = array_unique(array_merge($cc_phids, $existing_cc));
       $object->setCCPHIDs($new_cc);
       $save_again = true;
     }
 
     $assign_phid = $adapter->getAssignPHID();
     if ($assign_phid) {
       $object->setOwnerPHID($assign_phid);
       $save_again = true;
     }
 
     $project_phids = $adapter->getProjectPHIDs();
     if ($project_phids) {
       $existing_projects = $object->getProjectPHIDs();
       $new_projects = array_unique(
         array_merge($project_phids, $existing_projects));
       $object->setProjectPHIDs($new_projects);
       $save_again = true;
     }
 
     if ($save_again) {
       $object->save();
     }
   }
 
   protected function requireCapabilities(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     parent::requireCapabilities($object, $xaction);
 
     $app_capability_map = array(
       ManiphestTransaction::TYPE_PRIORITY =>
         ManiphestCapabilityEditPriority::CAPABILITY,
       ManiphestTransaction::TYPE_STATUS =>
         ManiphestCapabilityEditStatus::CAPABILITY,
       ManiphestTransaction::TYPE_PROJECTS =>
         ManiphestCapabilityEditProjects::CAPABILITY,
       ManiphestTransaction::TYPE_OWNER =>
         ManiphestCapabilityEditAssign::CAPABILITY,
       PhabricatorTransactions::TYPE_EDIT_POLICY =>
         ManiphestCapabilityEditPolicies::CAPABILITY,
       PhabricatorTransactions::TYPE_VIEW_POLICY =>
         ManiphestCapabilityEditPolicies::CAPABILITY,
     );
 
     $transaction_type = $xaction->getTransactionType();
     $app_capability = idx($app_capability_map, $transaction_type);
 
     if ($app_capability) {
       $app = id(new PhabricatorApplicationQuery())
         ->setViewer($this->getActor())
         ->withClasses(array('PhabricatorApplicationManiphest'))
         ->executeOne();
       PhabricatorPolicyFilter::requireCapability(
         $this->getActor(),
         $app,
         $app_capability);
     }
   }
 
 
   private function getNextSubpriority($pri, $sub) {
 
     if ($sub === null) {
       $next = id(new ManiphestTask())->loadOneWhere(
         'priority = %d ORDER BY subpriority ASC LIMIT 1',
         $pri);
       if ($next) {
         return $next->getSubpriority() - ((double)(2 << 16));
       }
     } else {
       $next = id(new ManiphestTask())->loadOneWhere(
         'priority = %d AND subpriority > %s ORDER BY subpriority ASC LIMIT 1',
         $pri,
         $sub);
       if ($next) {
         return ($sub + $next->getSubpriority()) / 2;
       }
     }
 
     return (double)(2 << 32);
   }
 
 }
diff --git a/src/applications/maniphest/storage/ManiphestTransaction.php b/src/applications/maniphest/storage/ManiphestTransaction.php
index 627066cddd..b4c1a8bb1a 100644
--- a/src/applications/maniphest/storage/ManiphestTransaction.php
+++ b/src/applications/maniphest/storage/ManiphestTransaction.php
@@ -1,672 +1,716 @@
 <?php
 
 final class ManiphestTransaction
   extends PhabricatorApplicationTransaction {
 
   const TYPE_TITLE = 'title';
   const TYPE_STATUS = 'status';
   const TYPE_DESCRIPTION = 'description';
   const TYPE_OWNER  = 'reassign';
   const TYPE_CCS = 'ccs';
   const TYPE_PROJECTS = 'projects';
   const TYPE_PRIORITY = 'priority';
   const TYPE_EDGE = 'edge';
   const TYPE_ATTACH = 'attach';
   const TYPE_SUBPRIORITY = 'subpriority';
+  const TYPE_PROJECT_COLUMN = 'projectcolumn';
 
   public function getApplicationName() {
     return 'maniphest';
   }
 
   public function getApplicationTransactionType() {
     return ManiphestPHIDTypeTask::TYPECONST;
   }
 
   public function getApplicationTransactionCommentObject() {
     return new ManiphestTransactionComment();
   }
 
+  public function shouldGenerateOldValue() {
+    $generate = true;
+    switch ($this->getTransactionType()) {
+      case self::TYPE_PROJECT_COLUMN:
+      case self::TYPE_EDGE:
+        $generate = false;
+        break;
+      default:
+        $generate = true;
+        break;
+    }
+    return $generate;
+  }
+
   public function getRequiredHandlePHIDs() {
     $phids = parent::getRequiredHandlePHIDs();
 
     $new = $this->getNewValue();
     $old = $this->getOldValue();
 
     switch ($this->getTransactionType()) {
       case self::TYPE_OWNER:
         if ($new) {
           $phids[] = $new;
         }
 
         if ($old) {
           $phids[] = $old;
         }
         break;
       case self::TYPE_CCS:
       case self::TYPE_PROJECTS:
         $phids = array_mergev(
           array(
             $phids,
             nonempty($old, array()),
             nonempty($new, array()),
           ));
         break;
+      case self::TYPE_PROJECT_COLUMN:
+        $phids[] = $new['projectPHID'];
+        $phids[] = head($new['columnPHIDs']);
+        break;
       case self::TYPE_EDGE:
         $phids = array_mergev(
           array(
             $phids,
             array_keys(nonempty($old, array())),
             array_keys(nonempty($new, array())),
           ));
         break;
       case self::TYPE_ATTACH:
         $old = nonempty($old, array());
         $new = nonempty($new, array());
         $phids = array_mergev(
           array(
             $phids,
             array_keys(idx($new, 'FILE', array())),
             array_keys(idx($old, 'FILE', array())),
           ));
         break;
 
     }
 
     return $phids;
   }
 
   public function shouldHide() {
     switch ($this->getTransactionType()) {
       case self::TYPE_TITLE:
       case self::TYPE_DESCRIPTION:
       case self::TYPE_PRIORITY:
         if ($this->getOldValue() === null) {
           return true;
         } else {
           return false;
         }
         break;
       case self::TYPE_SUBPRIORITY:
         return true;
     }
 
     return false;
   }
 
   public function getActionStrength() {
     switch ($this->getTransactionType()) {
       case self::TYPE_STATUS:
         return 1.3;
       case self::TYPE_OWNER:
         return 1.2;
       case self::TYPE_PRIORITY:
         return 1.1;
     }
 
     return parent::getActionStrength();
   }
 
 
   public function getColor() {
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case self::TYPE_OWNER:
         if ($this->getAuthorPHID() == $new) {
           return 'green';
         } else if (!$new) {
           return 'black';
         } else if (!$old) {
           return 'green';
         } else {
           return 'green';
         }
 
       case self::TYPE_STATUS:
         if ($new == ManiphestTaskStatus::STATUS_OPEN) {
           return 'green';
         } else {
           return 'black';
         }
 
       case self::TYPE_PRIORITY:
         if ($old == ManiphestTaskPriority::getDefaultPriority()) {
           return 'green';
         } else if ($old > $new) {
           return 'grey';
         } else {
           return 'yellow';
         }
 
     }
 
     return parent::getColor();
   }
 
   public function getActionName() {
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case self::TYPE_TITLE:
         return pht('Retitled');
 
       case self::TYPE_STATUS:
         switch ($new) {
           case ManiphestTaskStatus::STATUS_OPEN:
             if ($old === null) {
               return pht('Created');
             } else {
               return pht('Reopened');
             }
           case ManiphestTaskStatus::STATUS_CLOSED_SPITE:
             return pht('Spited');
           case ManiphestTaskStatus::STATUS_CLOSED_DUPLICATE:
             return pht('Merged');
           default:
             return pht('Closed');
         }
 
       case self::TYPE_DESCRIPTION:
         return pht('Edited');
 
       case self::TYPE_OWNER:
         if ($this->getAuthorPHID() == $new) {
           return pht('Claimed');
         } else if (!$new) {
           return pht('Up For Grabs');
         } else if (!$old) {
           return pht('Assigned');
         } else {
           return pht('Reassigned');
         }
 
       case self::TYPE_CCS:
         return pht('Changed CC');
 
       case self::TYPE_PROJECTS:
         return pht('Changed Projects');
 
+      case self::TYPE_PROJECT_COLUMN:
+        return pht('Changed Project Column');
+
       case self::TYPE_PRIORITY:
         if ($old == ManiphestTaskPriority::getDefaultPriority()) {
           return pht('Triaged');
         } else if ($old > $new) {
           return pht('Lowered Priority');
         } else {
           return pht('Raised Priority');
         }
 
       case self::TYPE_EDGE:
       case self::TYPE_ATTACH:
         return pht('Attached');
     }
 
     return parent::getActionName();
   }
 
   public function getIcon() {
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case self::TYPE_OWNER:
         return 'user';
 
       case self::TYPE_CCS:
         return 'meta-mta';
 
       case self::TYPE_TITLE:
         return 'edit';
 
       case self::TYPE_STATUS:
         switch ($new) {
           case ManiphestTaskStatus::STATUS_OPEN:
             return 'create';
           case ManiphestTaskStatus::STATUS_CLOSED_SPITE:
             return 'dislike';
           case ManiphestTaskStatus::STATUS_CLOSED_DUPLICATE:
             return 'delete';
           default:
             return 'check';
         }
 
       case self::TYPE_DESCRIPTION:
         return 'edit';
 
       case self::TYPE_PROJECTS:
         return 'project';
 
+      case self::TYPE_PROJECT_COLUMN:
+        return 'workboard';
+
       case self::TYPE_PRIORITY:
         if ($old == ManiphestTaskPriority::getDefaultPriority()) {
           return 'normal-priority';
           return pht('Triaged');
         } else if ($old > $new) {
           return 'lower-priority';
         } else {
           return 'raise-priority';
         }
 
       case self::TYPE_EDGE:
       case self::TYPE_ATTACH:
         return 'attach';
 
     }
 
     return parent::getIcon();
   }
 
 
 
   public function getTitle() {
     $author_phid = $this->getAuthorPHID();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case self::TYPE_TITLE:
         return pht(
           '%s changed the title from "%s" to "%s".',
           $this->renderHandleLink($author_phid),
           $old,
           $new);
 
       case self::TYPE_DESCRIPTION:
         return pht(
           '%s edited the task description.',
           $this->renderHandleLink($author_phid));
 
       case self::TYPE_STATUS:
         switch ($new) {
           case ManiphestTaskStatus::STATUS_OPEN:
             if ($old === null) {
               return pht(
                 '%s created this task.',
                 $this->renderHandleLink($author_phid));
             } else {
               return pht(
                 '%s reopened this task.',
                 $this->renderHandleLink($author_phid));
             }
 
           case ManiphestTaskStatus::STATUS_CLOSED_SPITE:
             return pht(
               '%s closed this task out of spite.',
               $this->renderHandleLink($author_phid));
           case ManiphestTaskStatus::STATUS_CLOSED_DUPLICATE:
             return pht(
               '%s closed this task as a duplicate.',
               $this->renderHandleLink($author_phid));
           default:
             $status_name = idx(
               ManiphestTaskStatus::getTaskStatusMap(),
               $new,
               '???');
             return pht(
               '%s closed this task as "%s".',
               $this->renderHandleLink($author_phid),
               $status_name);
         }
 
       case self::TYPE_OWNER:
         if ($author_phid == $new) {
           return pht(
             '%s claimed this task.',
             $this->renderHandleLink($author_phid));
         } else if (!$new) {
           return pht(
             '%s placed this task up for grabs.',
             $this->renderHandleLink($author_phid));
         } else if (!$old) {
           return pht(
             '%s assigned this task to %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($new));
         } else {
           return pht(
             '%s reassigned this task from %s to %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($old),
             $this->renderHandleLink($new));
         }
 
       case self::TYPE_PROJECTS:
         $added = array_diff($new, $old);
         $removed = array_diff($old, $new);
         if ($added && !$removed) {
           return pht(
             '%s added %d project(s): %s',
             $this->renderHandleLink($author_phid),
             count($added),
             $this->renderHandleList($added));
         } else if ($removed && !$added) {
           return pht(
             '%s removed %d project(s): %s',
             $this->renderHandleLink($author_phid),
             count($removed),
             $this->renderHandleList($removed));
         } else if ($removed && $added) {
           return pht(
             '%s changed project(s), added %d: %s; removed %d: %s',
             $this->renderHandleLink($author_phid),
             count($added),
             $this->renderHandleList($added),
             count($removed),
             $this->renderHandleList($removed));
         } else {
           // This is hit when rendering previews.
           return pht(
             '%s changed projects...',
             $this->renderHandleLink($author_phid));
         }
 
       case self::TYPE_PRIORITY:
         $old_name = ManiphestTaskPriority::getTaskPriorityName($old);
         $new_name = ManiphestTaskPriority::getTaskPriorityName($new);
 
         if ($old == ManiphestTaskPriority::getDefaultPriority()) {
           return pht(
             '%s triaged this task as "%s" priority.',
             $this->renderHandleLink($author_phid),
             $new_name);
         } else if ($old > $new) {
           return pht(
             '%s lowered the priority of this task from "%s" to "%s".',
             $this->renderHandleLink($author_phid),
             $old_name,
             $new_name);
         } else {
           return pht(
             '%s raised the priority of this task from "%s" to "%s".',
             $this->renderHandleLink($author_phid),
             $old_name,
             $new_name);
         }
 
       case self::TYPE_CCS:
         // TODO: Remove this when we switch to subscribers. Just reuse the
         // code in the parent.
         $clone = clone $this;
         $clone->setTransactionType(PhabricatorTransactions::TYPE_SUBSCRIBERS);
         return $clone->getTitle();
 
       case self::TYPE_EDGE:
         // TODO: Remove this when we switch to real edges. Just reuse the
         // code in the parent;
         $clone = clone $this;
         $clone->setTransactionType(PhabricatorTransactions::TYPE_EDGE);
         return $clone->getTitle();
 
       case self::TYPE_ATTACH:
         $old = nonempty($old, array());
         $new = nonempty($new, array());
         $new = array_keys(idx($new, 'FILE', array()));
         $old = array_keys(idx($old, 'FILE', array()));
 
         $added = array_diff($new, $old);
         $removed = array_diff($old, $new);
         if ($added && !$removed) {
           return pht(
             '%s attached %d file(s): %s',
             $this->renderHandleLink($author_phid),
             count($added),
             $this->renderHandleList($added));
         } else if ($removed && !$added) {
           return pht(
             '%s detached %d file(s): %s',
             $this->renderHandleLink($author_phid),
             count($removed),
             $this->renderHandleList($removed));
         } else {
           return pht(
             '%s changed file(s), attached %d: %s; detached %d: %s',
             $this->renderHandleLink($author_phid),
             count($added),
             $this->renderHandleList($added),
             count($removed),
             $this->renderHandleList($removed));
         }
 
+      case self::TYPE_PROJECT_COLUMN:
+        $project_phid = $new['projectPHID'];
+        $column_phid = head($new['columnPHIDs']);
+        return pht(
+          '%s moved this task to %s on the %s workboard.',
+          $this->renderHandleLink($author_phid),
+          $this->renderHandleLink($column_phid),
+          $this->renderHandleLink($project_phid));
+       break;
+
 
     }
 
     return parent::getTitle();
   }
 
   public function getTitleForFeed(PhabricatorFeedStory $story) {
     $author_phid = $this->getAuthorPHID();
     $object_phid = $this->getObjectPHID();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case self::TYPE_TITLE:
         return pht(
           '%s renamed %s from "%s" to "%s".',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid),
           $old,
           $new);
 
       case self::TYPE_DESCRIPTION:
         return pht(
           '%s edited the description of %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
 
       case self::TYPE_STATUS:
         switch ($new) {
           case ManiphestTaskStatus::STATUS_OPEN:
             if ($old === null) {
               return pht(
                 '%s created %s.',
                 $this->renderHandleLink($author_phid),
                 $this->renderHandleLink($object_phid));
             } else {
               return pht(
                 '%s reopened %s.',
                 $this->renderHandleLink($author_phid),
                 $this->renderHandleLink($object_phid));
             }
 
           case ManiphestTaskStatus::STATUS_CLOSED_SPITE:
             return pht(
               '%s closed %s out of spite.',
               $this->renderHandleLink($author_phid),
               $this->renderHandleLink($object_phid));
           case ManiphestTaskStatus::STATUS_CLOSED_DUPLICATE:
             return pht(
               '%s closed %s as a duplicate.',
               $this->renderHandleLink($author_phid),
               $this->renderHandleLink($object_phid));
           default:
             $status_name = idx(
               ManiphestTaskStatus::getTaskStatusMap(),
               $new,
               '???');
             return pht(
               '%s closed %s as "%s".',
               $this->renderHandleLink($author_phid),
               $this->renderHandleLink($object_phid),
               $status_name);
         }
 
       case self::TYPE_OWNER:
         if ($author_phid == $new) {
           return pht(
             '%s claimed %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid));
         } else if (!$new) {
           return pht(
             '%s placed %s up for grabs.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid));
         } else if (!$old) {
           return pht(
             '%s assigned %s to %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             $this->renderHandleLink($new));
         } else {
           return pht(
             '%s reassigned %s from %s to %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             $this->renderHandleLink($old),
             $this->renderHandleLink($new));
         }
 
       case self::TYPE_PROJECTS:
         $added = array_diff($new, $old);
         $removed = array_diff($old, $new);
         if ($added && !$removed) {
           return pht(
             '%s added %d project(s) to %s: %s',
             $this->renderHandleLink($author_phid),
             count($added),
             $this->renderHandleLink($object_phid),
             $this->renderHandleList($added));
         } else if ($removed && !$added) {
           return pht(
             '%s removed %d project(s) from %s: %s',
             $this->renderHandleLink($author_phid),
             count($removed),
             $this->renderHandleLink($object_phid),
             $this->renderHandleList($removed));
         } else if ($removed && $added) {
           return pht(
             '%s changed project(s) of %s, added %d: %s; removed %d: %s',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             count($added),
             $this->renderHandleList($added),
             count($removed),
             $this->renderHandleList($removed));
         }
 
       case self::TYPE_PRIORITY:
         $old_name = ManiphestTaskPriority::getTaskPriorityName($old);
         $new_name = ManiphestTaskPriority::getTaskPriorityName($new);
 
         if ($old == ManiphestTaskPriority::getDefaultPriority()) {
           return pht(
             '%s triaged %s as "%s" priority.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             $new_name);
         } else if ($old > $new) {
           return pht(
             '%s lowered the priority of %s from "%s" to "%s".',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             $old_name,
             $new_name);
         } else {
           return pht(
             '%s raised the priority of %s from "%s" to "%s".',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             $old_name,
             $new_name);
         }
 
       case self::TYPE_CCS:
         // TODO: Remove this when we switch to subscribers. Just reuse the
         // code in the parent.
         $clone = clone $this;
         $clone->setTransactionType(PhabricatorTransactions::TYPE_SUBSCRIBERS);
         return $clone->getTitleForFeed($story);
 
       case self::TYPE_EDGE:
         // TODO: Remove this when we switch to real edges. Just reuse the
         // code in the parent;
         $clone = clone $this;
         $clone->setTransactionType(PhabricatorTransactions::TYPE_EDGE);
         return $clone->getTitleForFeed($story);
 
       case self::TYPE_ATTACH:
         $old = nonempty($old, array());
         $new = nonempty($new, array());
         $new = array_keys(idx($new, 'FILE', array()));
         $old = array_keys(idx($old, 'FILE', array()));
 
         $added = array_diff($new, $old);
         $removed = array_diff($old, $new);
         if ($added && !$removed) {
           return pht(
             '%s attached %d file(s) of %s: %s',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             count($added),
             $this->renderHandleList($added));
         } else if ($removed && !$added) {
           return pht(
             '%s detached %d file(s) of %s: %s',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             count($removed),
             $this->renderHandleList($removed));
         } else {
           return pht(
             '%s changed file(s) for %s, attached %d: %s; detached %d: %s',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             count($added),
             $this->renderHandleList($added),
             count($removed),
             $this->renderHandleList($removed));
         }
 
+      case self::TYPE_PROJECT_COLUMN:
+        $project_phid = $new['projectPHID'];
+        $column_phid = head($new['columnPHIDs']);
+        return pht(
+          '%s moved this task to %s on the %s workboard.',
+          $this->renderHandleLink($author_phid),
+          $this->renderHandleLink($column_phid),
+          $this->renderHandleLink($project_phid));
+       break;
     }
 
     return parent::getTitleForFeed($story);
   }
 
   public function hasChangeDetails() {
     switch ($this->getTransactionType()) {
       case self::TYPE_DESCRIPTION:
         return true;
     }
     return parent::hasChangeDetails();
   }
 
   public function renderChangeDetails(PhabricatorUser $viewer) {
     return $this->renderTextCorpusChangeDetails(
       $viewer,
       $this->getOldValue(),
       $this->getNewValue());
   }
 
   public function getMailTags() {
     $tags = array();
     switch ($this->getTransactionType()) {
       case self::TYPE_STATUS:
         $tags[] = MetaMTANotificationType::TYPE_MANIPHEST_STATUS;
         break;
       case self::TYPE_OWNER:
         $tags[] = MetaMTANotificationType::TYPE_MANIPHEST_OWNER;
         break;
       case self::TYPE_CCS:
         $tags[] = MetaMTANotificationType::TYPE_MANIPHEST_CC;
         break;
       case self::TYPE_PROJECTS:
         $tags[] = MetaMTANotificationType::TYPE_MANIPHEST_PROJECTS;
         break;
       case self::TYPE_PRIORITY:
         $tags[] = MetaMTANotificationType::TYPE_MANIPHEST_PRIORITY;
         break;
       case PhabricatorTransactions::TYPE_COMMENT:
         $tags[] = MetaMTANotificationType::TYPE_MANIPHEST_COMMENT;
         break;
       default:
         $tags[] = MetaMTANotificationType::TYPE_MANIPHEST_OTHER;
         break;
     }
     return $tags;
   }
 
 
 }
diff --git a/src/applications/project/controller/PhabricatorProjectMoveController.php b/src/applications/project/controller/PhabricatorProjectMoveController.php
index be17d3362d..105e81cdeb 100644
--- a/src/applications/project/controller/PhabricatorProjectMoveController.php
+++ b/src/applications/project/controller/PhabricatorProjectMoveController.php
@@ -1,143 +1,111 @@
 <?php
 
 final class PhabricatorProjectMoveController
   extends PhabricatorProjectController {
 
   private $id;
 
   public function willProcessRequest(array $data) {
     $this->id = $data['id'];
   }
 
   public function processRequest() {
     $request = $this->getRequest();
     $viewer = $request->getUser();
 
     $column_phid = $request->getStr('columnPHID');
     $object_phid = $request->getStr('objectPHID');
     $after_phid = $request->getStr('afterPHID');
 
     $project = id(new PhabricatorProjectQuery())
       ->setViewer($viewer)
       ->requireCapabilities(
         array(
           PhabricatorPolicyCapability::CAN_VIEW,
           PhabricatorPolicyCapability::CAN_EDIT,
         ))
       ->withIDs(array($this->id))
       ->executeOne();
     if (!$project) {
       return new Aphront404Response();
     }
 
     // NOTE: I'm not requiring EDIT on the object for now, since we require
     // EDIT on the project anyway and this relationship is more owned by the
     // project than the object. Maybe this is worth revisiting eventually.
 
     $object = id(new PhabricatorObjectQuery())
       ->setViewer($viewer)
       ->withPHIDs(array($object_phid))
       ->executeOne();
 
     if (!$object) {
       return new Aphront404Response();
     }
 
     $columns = id(new PhabricatorProjectColumnQuery())
       ->setViewer($viewer)
       ->withProjectPHIDs(array($project->getPHID()))
       ->execute();
 
     $columns = mpull($columns, null, 'getPHID');
-    if (empty($columns[$column_phid])) {
+    $column = idx($columns, $column_phid);
+    if (!$column) {
       // User is trying to drop this object into a nonexistent column, just kick
       // them out.
       return new Aphront404Response();
     }
 
+    $xactions = array();
+
     $edge_type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_COLUMN;
 
     $query = id(new PhabricatorEdgeQuery())
       ->withSourcePHIDs(array($object->getPHID()))
       ->withEdgeTypes(array($edge_type))
       ->withDestinationPHIDs(array_keys($columns));
 
     $query->execute();
 
     $edge_phids = $query->getDestinationPHIDs();
 
-    $this->rewriteEdges(
-      $object->getPHID(),
-      $edge_type,
-      $column_phid,
-      $edge_phids);
+    $xactions[] = id(new ManiphestTransaction())
+      ->setTransactionType(ManiphestTransaction::TYPE_PROJECT_COLUMN)
+      ->setNewValue(array(
+        'columnPHIDs' => array($column->getPHID()),
+        'projectPHID' => $column->getProjectPHID()))
+      ->setOldValue(array(
+        'columnPHIDs' => $edge_phids,
+        'projectPHID' => $column->getProjectPHID()));
 
     if ($after_phid) {
       $after_task = id(new ManiphestTaskQuery())
         ->setViewer($viewer)
         ->withPHIDs(array($after_phid))
         ->requireCapabilities(array(PhabricatorPolicyCapability::CAN_EDIT))
         ->executeOne();
       if (!$after_task) {
         return new Aphront404Response();
       }
       $after_pri = $after_task->getPriority();
       $after_sub = $after_task->getSubpriority();
 
-      $xactions = array(id(new ManiphestTransaction())
+      $xactions[] = id(new ManiphestTransaction())
         ->setTransactionType(ManiphestTransaction::TYPE_SUBPRIORITY)
         ->setNewValue(array(
           'newPriority' => $after_pri,
-          'newSubpriorityBase' => $after_sub)));
-      $editor = id(new ManiphestTransactionEditor())
-        ->setActor($viewer)
-        ->setContinueOnMissingFields(true)
-        ->setContinueOnNoEffect(true)
-        ->setContentSourceFromRequest($request);
-
-      $editor->applyTransactions($object, $xactions);
-    }
-
-    return id(new AphrontAjaxResponse())->setContent(array());
-  }
-
-  private function rewriteEdges($src, $edge_type, $dst, array $edges) {
-    $viewer = $this->getRequest()->getUser();
-
-    // NOTE: Normally, we expect only one edge to exist, but this works in a
-    // general way so it will repair any stray edges.
-
-    $remove = array();
-    $edge_missing = true;
-    foreach ($edges as $phid) {
-      if ($phid == $dst) {
-        $edge_missing = false;
-      } else {
-        $remove[] = $phid;
-      }
-    }
-
-    $add = array();
-    if ($edge_missing) {
-      $add[] = $dst;
-    }
-
-    if (!$add && !$remove) {
-      return;
+          'newSubpriorityBase' => $after_sub));
     }
 
-    $editor = id(new PhabricatorEdgeEditor())
+    $editor = id(new ManiphestTransactionEditor())
       ->setActor($viewer)
-      ->setSuppressEvents(true);
+      ->setContinueOnMissingFields(true)
+      ->setContinueOnNoEffect(true)
+      ->setContentSourceFromRequest($request);
 
-    foreach ($add as $phid) {
-      $editor->addEdge($src, $edge_type, $phid);
-    }
-    foreach ($remove as $phid) {
-      $editor->removeEdge($src, $edge_type, $phid);
-    }
+    $editor->applyTransactions($object, $xactions);
 
-    $editor->save();
+    return id(new AphrontAjaxResponse())->setContent(array());
   }
 
 }
diff --git a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
index 387fe6b57c..365a34ddde 100644
--- a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
+++ b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
@@ -1,1949 +1,1940 @@
 <?php
 
 /**
  * @task mail   Sending Mail
  * @task feed   Publishing Feed Stories
  * @task search Search Index
  * @task files  Integration with Files
  */
 abstract class PhabricatorApplicationTransactionEditor
   extends PhabricatorEditor {
 
   private $contentSource;
   private $object;
   private $xactions;
 
   private $isNewObject;
   private $mentionedPHIDs;
   private $continueOnNoEffect;
   private $continueOnMissingFields;
   private $parentMessageID;
   private $heraldAdapter;
   private $heraldTranscript;
   private $subscribers;
 
   private $isPreview;
 
   /**
    * 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;
   }
 
   protected 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 getTransactionTypes() {
     $types = array();
 
     if ($this->object instanceof PhabricatorSubscribableInterface) {
       $types[] = PhabricatorTransactions::TYPE_SUBSCRIBERS;
     }
 
     if ($this->object instanceof PhabricatorCustomFieldInterface) {
       $types[] = PhabricatorTransactions::TYPE_CUSTOMFIELD;
     }
 
     return $types;
   }
 
   private function adjustTransactionValues(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     $old = $this->getTransactionOldValue($object, $xaction);
     $xaction->setOldValue($old);
 
     $new = $this->getTransactionNewValue($object, $xaction);
     $xaction->setNewValue($new);
   }
 
   private function getTransactionOldValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return array_values($this->subscribers);
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         return $object->getViewPolicy();
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         return $object->getEditPolicy();
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return $object->getJoinPolicy();
       case PhabricatorTransactions::TYPE_EDGE:
         $edge_type = $xaction->getMetadataValue('edge:type');
         if (!$edge_type) {
           throw new Exception("Edge transaction has no 'edge:type'!");
         }
 
         $old_edges = array();
         if ($object->getPHID()) {
           $edge_src = $object->getPHID();
 
           $old_edges = id(new PhabricatorEdgeQuery())
             ->withSourcePHIDs(array($edge_src))
             ->withEdgeTypes(array($edge_type))
             ->needEdgeData(true)
             ->execute();
 
           $old_edges = $old_edges[$edge_src][$edge_type];
         }
         return $old_edges;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         // NOTE: Custom fields have their old value pre-populated when they are
         // built by PhabricatorCustomFieldList.
         return $xaction->getOldValue();
       case PhabricatorTransactions::TYPE_COMMENT:
         return null;
       default:
         return $this->getCustomTransactionOldValue($object, $xaction);
     }
   }
 
   private function getTransactionNewValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return $this->getPHIDTransactionNewValue($xaction);
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return $xaction->getNewValue();
       case PhabricatorTransactions::TYPE_EDGE:
         return $this->getEdgeTransactionNewValue($xaction);
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->getNewValueFromApplicationTransactions($xaction);
       case PhabricatorTransactions::TYPE_COMMENT:
         return null;
       default:
         return $this->getCustomTransactionNewValue($object, $xaction);
     }
   }
 
   protected function getCustomTransactionOldValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     throw new Exception("Capability not supported!");
   }
 
   protected function getCustomTransactionNewValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     throw new Exception("Capability not supported!");
   }
 
   protected function transactionHasEffect(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return $xaction->hasComment();
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->getApplicationTransactionHasEffect($xaction);
       case PhabricatorTransactions::TYPE_EDGE:
         // A straight value comparison here doesn't always get the right
         // result, because newly added edges aren't fully populated. Instead,
         // compare the changes in a more granular way.
         $old = $xaction->getOldValue();
         $new = $xaction->getNewValue();
 
         $old_dst = array_keys($old);
         $new_dst = array_keys($new);
 
         // NOTE: For now, we don't consider edge reordering to be a change.
         // We have very few order-dependent edges and effectively no order
         // oriented UI. This might change in the future.
         sort($old_dst);
         sort($new_dst);
 
         if ($old_dst !== $new_dst) {
           // We've added or removed edges, so this transaction definitely
           // has an effect.
           return true;
         }
 
         // We haven't added or removed edges, but we might have changed
         // edge data.
         foreach ($old as $key => $old_value) {
           $new_value = $new[$key];
           if ($old_value['data'] !== $new_value['data']) {
             return true;
           }
         }
 
         return false;
     }
 
     return ($xaction->getOldValue() !== $xaction->getNewValue());
   }
 
   protected function shouldApplyInitialEffects(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return false;
   }
 
   protected function applyInitialEffects(
     PhabricatorLiskDAO $object,
     array $xactions) {
     throw new Exception('Not implemented.');
   }
 
   private function applyInternalEffects(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         $object->setViewPolicy($xaction->getNewValue());
         break;
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         $object->setEditPolicy($xaction->getNewValue());
         break;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->applyApplicationTransactionInternalEffects($xaction);
     }
     return $this->applyCustomInternalTransaction($object, $xaction);
   }
 
   private function applyExternalEffects(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $subeditor = id(new PhabricatorSubscriptionsEditor())
           ->setObject($object)
           ->setActor($this->requireActor());
 
         $old_map = array_fuse($xaction->getOldValue());
         $new_map = array_fuse($xaction->getNewValue());
 
         $subeditor->unsubscribe(
           array_keys(
             array_diff_key($old_map, $new_map)));
 
         $subeditor->subscribeExplicit(
           array_keys(
             array_diff_key($new_map, $old_map)));
 
         $subeditor->save();
 
         // for the rest of these edits, subscribers should include those just
         // added as well as those just removed.
         $subscribers = array_unique(array_merge(
           $this->subscribers,
           $xaction->getOldValue(),
           $xaction->getNewValue()));
         $this->subscribers = $subscribers;
 
         break;
       case PhabricatorTransactions::TYPE_EDGE:
         $old = $xaction->getOldValue();
         $new = $xaction->getNewValue();
         $src = $object->getPHID();
         $type = $xaction->getMetadataValue('edge:type');
 
         foreach ($new as $dst_phid => $edge) {
           $new[$dst_phid]['src'] = $src;
         }
 
         $editor = id(new PhabricatorEdgeEditor())
           ->setActor($this->getActor());
 
         foreach ($old as $dst_phid => $edge) {
           if (!empty($new[$dst_phid])) {
             if ($old[$dst_phid]['data'] === $new[$dst_phid]['data']) {
               continue;
             }
           }
           $editor->removeEdge($src, $type, $dst_phid);
         }
 
         foreach ($new as $dst_phid => $edge) {
           if (!empty($old[$dst_phid])) {
             if ($old[$dst_phid]['data'] === $new[$dst_phid]['data']) {
               continue;
             }
           }
 
           $data = array(
             'data' => $edge['data'],
           );
 
           $editor->addEdge($src, $type, $dst_phid, $data);
         }
 
         $editor->save();
         break;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getCustomFieldForTransaction($object, $xaction);
         return $field->applyApplicationTransactionExternalEffects($xaction);
     }
 
     return $this->applyCustomExternalTransaction($object, $xaction);
   }
 
   protected function applyCustomInternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     $type = $xaction->getTransactionType();
     throw new Exception(
       "Transaction type '{$type}' is missing an internal apply ".
       "implementation!");
   }
 
   protected function applyCustomExternalTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     $type = $xaction->getTransactionType();
     throw new Exception(
       "Transaction type '{$type}' is missing an external apply ".
       "implementation!");
   }
 
   /**
    * Fill in a transaction's common values, like author and content source.
    */
   protected function populateTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     $actor = $this->getActor();
 
     // TODO: This needs to be more sophisticated once we have meta-policies.
     $xaction->setViewPolicy(PhabricatorPolicies::POLICY_PUBLIC);
     $xaction->setEditPolicy($actor->getPHID());
 
     $xaction->setAuthorPHID($actor->getPHID());
     $xaction->setContentSource($this->getContentSource());
     $xaction->attachViewer($actor);
     $xaction->attachObject($object);
 
     if ($object->getPHID()) {
       $xaction->setObjectPHID($object->getPHID());
     }
 
     return $xaction;
   }
 
 
   protected function applyFinalEffects(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return $xactions;
   }
 
   public function setContentSource(PhabricatorContentSource $content_source) {
     $this->contentSource = $content_source;
     return $this;
   }
 
   public function setContentSourceFromRequest(AphrontRequest $request) {
     return $this->setContentSource(
       PhabricatorContentSource::newFromRequest($request));
   }
 
   public function getContentSource() {
     return $this->contentSource;
   }
 
   final public function applyTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $this->object = $object;
     $this->xactions = $xactions;
     $this->isNewObject = ($object->getPHID() === null);
 
     $this->validateEditParameters($object, $xactions);
 
     $actor = $this->requireActor();
 
     // NOTE: Some transaction expansion requires that the edited object be
     // attached.
     foreach ($xactions as $xaction) {
       $xaction->attachObject($object);
       $xaction->attachViewer($actor);
     }
 
     $xactions = $this->expandTransactions($object, $xactions);
     $xactions = $this->expandSupportTransactions($object, $xactions);
     $xactions = $this->combineTransactions($xactions);
 
     foreach ($xactions as $xaction) {
       $xaction = $this->populateTransaction($object, $xaction);
     }
 
     $is_preview = $this->getIsPreview();
     $read_locking = false;
     $transaction_open = false;
 
     if (!$is_preview) {
       $errors = array();
       $type_map = mgroup($xactions, 'getTransactionType');
       foreach ($this->getTransactionTypes() as $type) {
         $type_xactions = idx($type_map, $type, array());
         $errors[] = $this->validateTransaction($object, $type, $type_xactions);
       }
 
       $errors = array_mergev($errors);
 
       $continue_on_missing = $this->getContinueOnMissingFields();
       foreach ($errors as $key => $error) {
         if ($continue_on_missing && $error->getIsMissingFieldError()) {
           unset($errors[$key]);
         }
       }
 
       if ($errors) {
         throw new PhabricatorApplicationTransactionValidationException($errors);
       }
 
       $file_phids = $this->extractFilePHIDs($object, $xactions);
 
       if ($object->getID()) {
         foreach ($xactions as $xaction) {
 
           // If any of the transactions require a read lock, hold one and
           // reload the object. We need to do this fairly early so that the
           // call to `adjustTransactionValues()` (which populates old values)
           // is based on the synchronized state of the object, which may differ
           // from the state when it was originally loaded.
 
           if ($this->shouldReadLock($object, $xaction)) {
             $object->openTransaction();
             $object->beginReadLocking();
             $transaction_open = true;
             $read_locking = true;
             $object->reload();
             break;
           }
         }
       }
 
       if ($this->shouldApplyInitialEffects($object, $xactions)) {
         if (!$transaction_open) {
           $object->openTransaction();
           $transaction_open = true;
         }
       }
     }
 
     if ($this->shouldApplyInitialEffects($object, $xactions)) {
       $this->applyInitialEffects($object, $xactions);
     }
 
     foreach ($xactions as $xaction) {
       $this->adjustTransactionValues($object, $xaction);
     }
 
     $xactions = $this->filterTransactions($object, $xactions);
 
     if (!$xactions) {
       if ($read_locking) {
         $object->endReadLocking();
         $read_locking = false;
       }
       if ($transaction_open) {
         $object->killTransaction();
         $transaction_open = false;
       }
       return array();
     }
 
     // Now that we've merged, filtered, and combined transactions, check for
     // required capabilities.
     foreach ($xactions as $xaction) {
       $this->requireCapabilities($object, $xaction);
     }
 
     $xactions = $this->sortTransactions($xactions);
 
     if ($is_preview) {
       $this->loadHandles($xactions);
       return $xactions;
     }
 
     $comment_editor = id(new PhabricatorApplicationTransactionCommentEditor())
       ->setActor($actor)
       ->setContentSource($this->getContentSource());
 
     if (!$transaction_open) {
       $object->openTransaction();
     }
 
       foreach ($xactions as $xaction) {
         $this->applyInternalEffects($object, $xaction);
       }
 
       $object->save();
 
       foreach ($xactions as $xaction) {
         $xaction->setObjectPHID($object->getPHID());
         if ($xaction->getComment()) {
           $xaction->setPHID($xaction->generatePHID());
           $comment_editor->applyEdit($xaction, $xaction->getComment());
         } else {
           $xaction->save();
         }
       }
 
       if ($file_phids) {
         $this->attachFiles($object, $file_phids);
       }
 
       foreach ($xactions as $xaction) {
         $this->applyExternalEffects($object, $xaction);
       }
 
       if ($this->supportsHerald()) {
         $this->applyHeraldRules($object, $xactions);
       }
 
       $xactions = $this->applyFinalEffects($object, $xactions);
 
       if ($read_locking) {
         $object->endReadLocking();
         $read_locking = false;
       }
 
     $object->saveTransaction();
 
     $this->loadHandles($xactions);
 
     $mail = null;
     if ($this->shouldSendMail($object, $xactions)) {
       $mail = $this->sendMail($object, $xactions);
     }
 
     if ($this->supportsSearch()) {
       id(new PhabricatorSearchIndexer())
         ->queueDocumentForIndexing($object->getPHID());
     }
 
     if ($this->supportsFeed()) {
       $mailed = array();
       if ($mail) {
         $mailed = $mail->buildRecipientList();
       }
       $this->publishFeedStory(
         $object,
         $xactions,
         $mailed);
     }
 
     $this->didApplyTransactions($xactions);
 
     if ($object instanceof PhabricatorCustomFieldInterface) {
       // Maybe this makes more sense to move into the search index itself? For
       // now I'm putting it here since I think we might end up with things that
       // need it to be up to date once the next page loads, but if we don't go
       // there we we could move it into search once search moves to the daemons.
 
       // It now happens in the search indexer as well, but the search indexer is
       // always daemonized, so the logic above still potentially holds. We could
       // possibly get rid of this. The major motivation for putting it in the
       // indexer was to enable reindexing to work.
 
       $fields = PhabricatorCustomField::getObjectFields(
         $object,
         PhabricatorCustomField::ROLE_APPLICATIONSEARCH);
       $fields->readFieldsFromStorage($object);
       $fields->rebuildIndexes($object);
     }
 
     return $xactions;
   }
 
   protected function didApplyTransactions(array $xactions) {
     // Hook for subclasses.
     return;
   }
 
 
   /**
    * Determine if the editor should hold a read lock on the object while
    * applying a transaction.
    *
    * If the editor does not hold a lock, two editors may read an object at the
    * same time, then apply their changes without any synchronization. For most
    * transactions, this does not matter much. However, it is important for some
    * transactions. For example, if an object has a transaction count on it, both
    * editors may read the object with `count = 23`, then independently update it
    * and save the object with `count = 24` twice. This will produce the wrong
    * state: the object really has 25 transactions, but the count is only 24.
    *
    * Generally, transactions fall into one of four buckets:
    *
    *   - Append operations: Actions like adding a comment to an object purely
    *     add information to its state, and do not depend on the current object
    *     state in any way. These transactions never need to hold locks.
    *   - Overwrite operations: Actions like changing the title or description
    *     of an object replace the current value with a new value, so the end
    *     state is consistent without a lock. We currently do not lock these
    *     transactions, although we may in the future.
    *   - Edge operations: Edge and subscription operations have internal
    *     synchronization which limits the damage race conditions can cause.
    *     We do not currently lock these transactions, although we may in the
    *     future.
    *   - Update operations: Actions like incrementing a count on an object.
    *     These operations generally should use locks, unless it is not
    *     important that the state remain consistent in the presence of races.
    *
    * @param   PhabricatorLiskDAO  Object being updated.
    * @param   PhabricatorApplicationTransaction Transaction being applied.
    * @return  bool                True to synchronize the edit with a lock.
    */
   protected function shouldReadLock(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     return false;
   }
 
   private function loadHandles(array $xactions) {
     $phids = array();
     foreach ($xactions as $key => $xaction) {
       $phids[$key] = $xaction->getRequiredHandlePHIDs();
     }
     $handles = array();
     $merged = array_mergev($phids);
     if ($merged) {
       $handles = id(new PhabricatorHandleQuery())
         ->setViewer($this->requireActor())
         ->withPHIDs($merged)
         ->execute();
     }
     foreach ($xactions as $key => $xaction) {
       $xaction->setHandles(array_select_keys($handles, $phids[$key]));
     }
   }
 
   private function loadSubscribers(PhabricatorLiskDAO $object) {
     if ($object->getPHID() &&
         ($object instanceof PhabricatorSubscribableInterface)) {
       $subs = PhabricatorSubscribersQuery::loadSubscribersForPHID(
         $object->getPHID());
       $this->subscribers = array_fuse($subs);
     } else {
       $this->subscribers = array();
     }
   }
 
   private function validateEditParameters(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     if (!$this->getContentSource()) {
       throw new Exception(
         "Call setContentSource() before applyTransactions()!");
     }
 
     // Do a bunch of sanity checks that the incoming transactions are fresh.
     // They should be unsaved and have only "transactionType" and "newValue"
     // set.
 
     $types = array_fill_keys($this->getTransactionTypes(), true);
 
     assert_instances_of($xactions, 'PhabricatorApplicationTransaction');
     foreach ($xactions as $xaction) {
       if ($xaction->getPHID() || $xaction->getID()) {
         throw new Exception(
           "You can not apply transactions which already have IDs/PHIDs!");
       }
       if ($xaction->getObjectPHID()) {
         throw new Exception(
           "You can not apply transactions which already have objectPHIDs!");
       }
       if ($xaction->getAuthorPHID()) {
         throw new Exception(
           "You can not apply transactions which already have authorPHIDs!");
       }
       if ($xaction->getCommentPHID()) {
         throw new Exception(
           "You can not apply transactions which already have commentPHIDs!");
       }
       if ($xaction->getCommentVersion() !== 0) {
         throw new Exception(
           "You can not apply transactions which already have commentVersions!");
       }
 
-      $exempt_types = array(
-        // CustomField logic currently prefills these before we enter the
-        // transaction editor.
-        PhabricatorTransactions::TYPE_CUSTOMFIELD => true,
-
-        // TODO: Remove this, this edge type is encumbered with a bunch of
-        // legacy nonsense.
-        ManiphestTransaction::TYPE_EDGE => true,
-      );
-
-      if (empty($exempt_types[$xaction->getTransactionType()])) {
-        if ($xaction->getOldValue() !== null) {
+      if (!$xaction->shouldGenerateOldValue()) {
+        if ($xaction->getOldValue() === null) {
           throw new Exception(
-            "You can not apply transactions which already have oldValue!");
+            'You can not apply transactions which should already have '.
+            'oldValue but do not!');
         }
       }
 
       $type = $xaction->getTransactionType();
       if (empty($types[$type])) {
         throw new Exception(
           pht(
             'Transaction has type "%s", but that transaction type is not '.
             'supported by this editor (%s).',
             $type,
             get_class($this)));
       }
     }
 
     // The actor must have permission to view and edit the object.
 
     $actor = $this->requireActor();
 
     PhabricatorPolicyFilter::requireCapability(
       $actor,
       $object,
       PhabricatorPolicyCapability::CAN_VIEW);
   }
 
   protected function requireCapabilities(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     switch ($xaction->getTransactionType()) {
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         // You must have the edit capability to alter the edit policy of an
         // object. For other default transaction types, we don't enforce
         // anything for the moment.
 
         PhabricatorPolicyFilter::requireCapability(
           $this->requireActor(),
           $object,
           PhabricatorPolicyCapability::CAN_EDIT);
         break;
     }
   }
 
   private function buildMentionTransaction(
     PhabricatorLiskDAO $object,
     array $xactions,
     array $blocks) {
 
     if (!($object instanceof PhabricatorSubscribableInterface)) {
       return null;
     }
 
     $texts = array_mergev($blocks);
     $phids = PhabricatorMarkupEngine::extractPHIDsFromMentions($texts);
 
     $this->mentionedPHIDs = $phids;
 
     if ($object->getPHID()) {
       // Don't try to subscribe already-subscribed mentions: we want to generate
       // a dialog about an action having no effect if the user explicitly adds
       // existing CCs, but not if they merely mention existing subscribers.
       $phids = array_diff($phids, $this->subscribers);
     }
 
     foreach ($phids as $key => $phid) {
       if ($object->isAutomaticallySubscribed($phid)) {
         unset($phids[$key]);
       }
     }
     $phids = array_values($phids);
 
     if (!$phids) {
       return null;
     }
 
     $xaction = newv(get_class(head($xactions)), array());
     $xaction->setTransactionType(PhabricatorTransactions::TYPE_SUBSCRIBERS);
     $xaction->setNewValue(array('+' => $phids));
 
     return $xaction;
   }
 
   protected function getRemarkupBlocksFromTransaction(
     PhabricatorApplicationTransaction $transaction) {
     return $transaction->getRemarkupBlocks();
   }
 
   protected function mergeTransactions(
     PhabricatorApplicationTransaction $u,
     PhabricatorApplicationTransaction $v) {
 
     $type = $u->getTransactionType();
 
     switch ($type) {
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return $this->mergePHIDOrEdgeTransactions($u, $v);
       case PhabricatorTransactions::TYPE_EDGE:
         $u_type = $u->getMetadataValue('edge:type');
         $v_type = $v->getMetadataValue('edge:type');
         if ($u_type == $v_type) {
           return $this->mergePHIDOrEdgeTransactions($u, $v);
         }
         return null;
     }
 
     // By default, do not merge the transactions.
     return null;
   }
 
   /**
    * Optionally expand transactions which imply other effects. For example,
    * resigning from a revision in Differential implies removing yourself as
    * a reviewer.
    */
   private function expandTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $results = array();
     foreach ($xactions as $xaction) {
       foreach ($this->expandTransaction($object, $xaction) as $expanded) {
         $results[] = $expanded;
       }
     }
 
     return $results;
   }
 
   protected function expandTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     return array($xaction);
   }
 
 
   private function expandSupportTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
     $this->loadSubscribers($object);
 
     $xactions = $this->applyImplicitCC($object, $xactions);
 
     $blocks = array();
     foreach ($xactions as $key => $xaction) {
       $blocks[$key] = $this->getRemarkupBlocksFromTransaction($xaction);
     }
 
     $mention_xaction = $this->buildMentionTransaction(
       $object,
       $xactions,
       $blocks);
     if ($mention_xaction) {
       $xactions[] = $mention_xaction;
     }
 
     // TODO: For now, this is just a placeholder.
     $engine = PhabricatorMarkupEngine::getEngine('extract');
 
     $block_xactions = $this->expandRemarkupBlockTransactions(
       $object,
       $xactions,
       $blocks,
       $engine);
 
     foreach ($block_xactions as $xaction) {
       $xactions[] = $xaction;
     }
 
     return $xactions;
   }
 
   private function expandRemarkupBlockTransactions(
     PhabricatorLiskDAO $object,
     array $xactions,
     $blocks,
     PhutilMarkupEngine $engine) {
     return $this->expandCustomRemarkupBlockTransactions(
       $object,
       $xactions,
       $blocks,
       $engine);
   }
 
   protected function expandCustomRemarkupBlockTransactions(
     PhabricatorLiskDAO $object,
     array $xactions,
     $blocks,
     PhutilMarkupEngine $engine) {
     return array();
   }
 
 
   /**
    * Attempt to combine similar transactions into a smaller number of total
    * transactions. For example, two transactions which edit the title of an
    * object can be merged into a single edit.
    */
   private function combineTransactions(array $xactions) {
     $stray_comments = array();
 
     $result = array();
     $types = array();
     foreach ($xactions as $key => $xaction) {
       $type = $xaction->getTransactionType();
       if (isset($types[$type])) {
         foreach ($types[$type] as $other_key) {
           $merged = $this->mergeTransactions($result[$other_key], $xaction);
           if ($merged) {
             $result[$other_key] = $merged;
 
             if ($xaction->getComment() &&
                 ($xaction->getComment() !== $merged->getComment())) {
               $stray_comments[] = $xaction->getComment();
             }
 
             if ($result[$other_key]->getComment() &&
                 ($result[$other_key]->getComment() !== $merged->getComment())) {
               $stray_comments[] = $result[$other_key]->getComment();
             }
 
             // Move on to the next transaction.
             continue 2;
           }
         }
       }
       $result[$key] = $xaction;
       $types[$type][] = $key;
     }
 
     // If we merged any comments away, restore them.
     foreach ($stray_comments as $comment) {
       $xaction = newv(get_class(head($result)), array());
       $xaction->setTransactionType(PhabricatorTransactions::TYPE_COMMENT);
       $xaction->setComment($comment);
       $result[] = $xaction;
     }
 
     return array_values($result);
   }
 
   protected function mergePHIDOrEdgeTransactions(
     PhabricatorApplicationTransaction $u,
     PhabricatorApplicationTransaction $v) {
 
     $result = $u->getNewValue();
     foreach ($v->getNewValue() as $key => $value) {
       if ($u->getTransactionType() == PhabricatorTransactions::TYPE_EDGE) {
         if (empty($result[$key])) {
           $result[$key] = $value;
         } else {
           // We're merging two lists of edge adds, sets, or removes. Merge
           // them by merging individual PHIDs within them.
           $merged = $result[$key];
 
           foreach ($value as $dst => $v_spec) {
             if (empty($merged[$dst])) {
               $merged[$dst] = $v_spec;
             } else {
               // Two transactions are trying to perform the same operation on
               // the same edge. Normalize the edge data and then merge it. This
               // allows transactions to specify how data merges execute in a
               // precise way.
 
               $u_spec = $merged[$dst];
 
               if (!is_array($u_spec)) {
                 $u_spec = array('dst' => $u_spec);
               }
               if (!is_array($v_spec)) {
                 $v_spec = array('dst' => $v_spec);
               }
 
               $ux_data = idx($u_spec, 'data', array());
               $vx_data = idx($v_spec, 'data', array());
 
               $merged_data = $this->mergeEdgeData(
                 $u->getMetadataValue('edge:type'),
                 $ux_data,
                 $vx_data);
 
               $u_spec['data'] = $merged_data;
               $merged[$dst] = $u_spec;
             }
           }
 
           $result[$key] = $merged;
         }
       } else {
         $result[$key] = array_merge($value, idx($result, $key, array()));
       }
     }
     $u->setNewValue($result);
 
     // When combining an "ignore" transaction with a normal transaction, make
     // sure we don't propagate the "ignore" flag.
     if (!$v->getIgnoreOnNoEffect()) {
       $u->setIgnoreOnNoEffect(false);
     }
 
     return $u;
   }
 
   protected function mergeEdgeData($type, array $u, array $v) {
     return $v + $u;
   }
 
   protected function getPHIDTransactionNewValue(
     PhabricatorApplicationTransaction $xaction) {
 
     $old = array_fuse($xaction->getOldValue());
 
     $new = $xaction->getNewValue();
     $new_add = idx($new, '+', array());
     unset($new['+']);
     $new_rem = idx($new, '-', array());
     unset($new['-']);
     $new_set = idx($new, '=', null);
     if ($new_set !== null) {
       $new_set = array_fuse($new_set);
     }
     unset($new['=']);
 
     if ($new) {
       throw new Exception(
         "Invalid 'new' value for PHID transaction. Value should contain only ".
         "keys '+' (add PHIDs), '-' (remove PHIDs) and '=' (set PHIDS).");
     }
 
     $result = array();
 
     foreach ($old as $phid) {
       if ($new_set !== null && empty($new_set[$phid])) {
         continue;
       }
       $result[$phid] = $phid;
     }
 
     if ($new_set !== null) {
       foreach ($new_set as $phid) {
         $result[$phid] = $phid;
       }
     }
 
     foreach ($new_add as $phid) {
       $result[$phid] = $phid;
     }
 
     foreach ($new_rem as $phid) {
       unset($result[$phid]);
     }
 
     return array_values($result);
   }
 
   protected function getEdgeTransactionNewValue(
     PhabricatorApplicationTransaction $xaction) {
 
     $new = $xaction->getNewValue();
     $new_add = idx($new, '+', array());
     unset($new['+']);
     $new_rem = idx($new, '-', array());
     unset($new['-']);
     $new_set = idx($new, '=', null);
     unset($new['=']);
 
     if ($new) {
       throw new Exception(
         "Invalid 'new' value for Edge transaction. Value should contain only ".
         "keys '+' (add edges), '-' (remove edges) and '=' (set edges).");
     }
 
     $old = $xaction->getOldValue();
 
     $lists = array($new_set, $new_add, $new_rem);
     foreach ($lists as $list) {
       $this->checkEdgeList($list);
     }
 
     $result = array();
     foreach ($old as $dst_phid => $edge) {
       if ($new_set !== null && empty($new_set[$dst_phid])) {
         continue;
       }
       $result[$dst_phid] = $this->normalizeEdgeTransactionValue(
         $xaction,
         $edge,
         $dst_phid);
     }
 
     if ($new_set !== null) {
       foreach ($new_set as $dst_phid => $edge) {
         $result[$dst_phid] = $this->normalizeEdgeTransactionValue(
           $xaction,
           $edge,
           $dst_phid);
       }
     }
 
     foreach ($new_add as $dst_phid => $edge) {
       $result[$dst_phid] = $this->normalizeEdgeTransactionValue(
         $xaction,
         $edge,
         $dst_phid);
     }
 
     foreach ($new_rem as $dst_phid => $edge) {
       unset($result[$dst_phid]);
     }
 
     return $result;
   }
 
   private function checkEdgeList($list) {
     if (!$list) {
       return;
     }
     foreach ($list as $key => $item) {
       if (phid_get_type($key) === PhabricatorPHIDConstants::PHID_TYPE_UNKNOWN) {
         throw new Exception(
           "Edge transactions must have destination PHIDs as in edge ".
           "lists (found key '{$key}').");
       }
       if (!is_array($item) && $item !== $key) {
         throw new Exception(
           "Edge transactions must have PHIDs or edge specs as values ".
           "(found value '{$item}').");
       }
     }
   }
 
   private function normalizeEdgeTransactionValue(
     PhabricatorApplicationTransaction $xaction,
     $edge,
     $dst_phid) {
 
     if (!is_array($edge)) {
       if ($edge != $dst_phid) {
         throw new Exception(
           pht(
             'Transaction edge data must either be the edge PHID or an edge '.
             'specification dictionary.'));
       }
       $edge = array();
     } else {
       foreach ($edge as $key => $value) {
         switch ($key) {
           case 'src':
           case 'dst':
           case 'type':
           case 'data':
           case 'dateCreated':
           case 'dateModified':
           case 'seq':
           case 'dataID':
             break;
           default:
             throw new Exception(
               pht(
                 'Transaction edge specification contains unexpected key '.
                 '"%s".',
                 $key));
         }
       }
     }
 
     $edge['dst'] = $dst_phid;
 
     $edge_type = $xaction->getMetadataValue('edge:type');
     if (empty($edge['type'])) {
       $edge['type'] = $edge_type;
     } else {
       if ($edge['type'] != $edge_type) {
         $this_type = $edge['type'];
         throw new Exception(
           "Edge transaction includes edge of type '{$this_type}', but ".
           "transaction is of type '{$edge_type}'. Each edge transaction must ".
           "alter edges of only one type.");
       }
     }
 
     if (!isset($edge['data'])) {
       $edge['data'] = array();
     }
 
     return $edge;
   }
 
   protected function sortTransactions(array $xactions) {
     $head = array();
     $tail = array();
 
     // Move bare comments to the end, so the actions precede them.
     foreach ($xactions as $xaction) {
       $type = $xaction->getTransactionType();
       if ($type == PhabricatorTransactions::TYPE_COMMENT) {
         $tail[] = $xaction;
       } else {
         $head[] = $xaction;
       }
     }
 
     return array_values(array_merge($head, $tail));
   }
 
 
   protected function filterTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $type_comment = PhabricatorTransactions::TYPE_COMMENT;
 
     $no_effect = array();
     $has_comment = false;
     $any_effect = false;
     foreach ($xactions as $key => $xaction) {
       if ($this->transactionHasEffect($object, $xaction)) {
         if ($xaction->getTransactionType() != $type_comment) {
           $any_effect = true;
         }
       } else if ($xaction->getIgnoreOnNoEffect()) {
         unset($xactions[$key]);
       } else {
         $no_effect[$key] = $xaction;
       }
       if ($xaction->hasComment()) {
         $has_comment = true;
       }
     }
 
     if (!$no_effect) {
       return $xactions;
     }
 
     if (!$this->getContinueOnNoEffect() && !$this->getIsPreview()) {
       throw new PhabricatorApplicationTransactionNoEffectException(
         $no_effect,
         $any_effect,
         $has_comment);
     }
 
     if (!$any_effect && !$has_comment) {
       // If we only have empty comment transactions, just drop them all.
       return array();
     }
 
     foreach ($no_effect as $key => $xaction) {
       if ($xaction->getComment()) {
         $xaction->setTransactionType($type_comment);
         $xaction->setOldValue(null);
         $xaction->setNewValue(null);
       } else {
         unset($xactions[$key]);
       }
     }
 
     return $xactions;
   }
 
 
   /**
    * Hook for validating transactions. This callback will be invoked for each
    * available transaction type, even if an edit does not apply any transactions
    * of that type. This allows you to raise exceptions when required fields are
    * missing, by detecting that the object has no field value and there is no
    * transaction which sets one.
    *
    * @param PhabricatorLiskDAO Object being edited.
    * @param string Transaction type to validate.
    * @param list<PhabricatorApplicationTransaction> Transactions of given type,
    *   which may be empty if the edit does not apply any transactions of the
    *   given type.
    * @return list<PhabricatorApplicationTransactionValidationError> List of
    *   validation errors.
    */
   protected function validateTransaction(
     PhabricatorLiskDAO $object,
     $type,
     array $xactions) {
 
     $errors = array();
     switch ($type) {
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         // Make sure the user isn't editing away their ability to edit this
         // object.
         foreach ($xactions as $xaction) {
           try {
             PhabricatorPolicyFilter::requireCapabilityWithForcedPolicy(
               $this->requireActor(),
               $object,
               PhabricatorPolicyCapability::CAN_EDIT,
               $xaction->getNewValue());
           } catch (PhabricatorPolicyException $ex) {
             $errors[] = array(
               new PhabricatorApplicationTransactionValidationError(
                 $type,
                 pht('Invalid'),
                 pht(
                   'You can not select this edit policy, because you would '.
                   'no longer be able to edit the object.'),
                 $xaction),
             );
           }
         }
         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);
 
         $role_xactions = PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS;
         foreach ($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);
   }
 
 
   /**
    * Check for a missing text field.
    *
    * A text field is missing if the object has no value and there are no
    * transactions which set a value, or if the transactions remove the value.
    * This method is intended to make implementing @{method:validateTransaction}
    * more convenient:
    *
    *   $missing = $this->validateIsEmptyTextField(
    *     $object->getName(),
    *     $xactions);
    *
    * This will return `true` if the net effect of the object and transactions
    * is an empty field.
    *
    * @param wild Current field value.
    * @param list<PhabricatorApplicationTransaction> Transactions editing the
    *          field.
    * @return bool True if the field will be an empty text field after edits.
    */
   protected function validateIsEmptyTextField($field_value, array $xactions) {
     if (strlen($field_value) && empty($xactions)) {
       return false;
     }
 
     if ($xactions && strlen(last($xactions)->getNewValue())) {
       return false;
     }
 
     return true;
   }
 
 
 /* -(  Implicit CCs  )------------------------------------------------------- */
 
 
   /**
    * When a user interacts with an object, we might want to add them to CC.
    */
   final public function applyImplicitCC(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     if (!($object instanceof PhabricatorSubscribableInterface)) {
       // If the object isn't subscribable, we can't CC them.
       return $xactions;
     }
 
     $actor_phid = $this->requireActor()->getPHID();
     if ($object->isAutomaticallySubscribed($actor_phid)) {
       // If they're auto-subscribed, don't CC them.
       return $xactions;
     }
 
     $should_cc = false;
     foreach ($xactions as $xaction) {
       if ($this->shouldImplyCC($object, $xaction)) {
         $should_cc = true;
         break;
       }
     }
 
     if (!$should_cc) {
       // Only some types of actions imply a CC (like adding a comment).
       return $xactions;
     }
 
     if ($object->getPHID()) {
       if (isset($this->subscribers[$actor_phid])) {
         // If the user is already subscribed, don't implicitly CC them.
         return $xactions;
       }
 
       $unsub = PhabricatorEdgeQuery::loadDestinationPHIDs(
         $object->getPHID(),
         PhabricatorEdgeConfig::TYPE_OBJECT_HAS_UNSUBSCRIBER);
       $unsub = array_fuse($unsub);
       if (isset($unsub[$actor_phid])) {
         // If the user has previously unsubscribed from this object explicitly,
         // don't implicitly CC them.
         return $xactions;
       }
     }
 
     $xaction = newv(get_class(head($xactions)), array());
     $xaction->setTransactionType(PhabricatorTransactions::TYPE_SUBSCRIBERS);
     $xaction->setNewValue(array('+' => array($actor_phid)));
 
     array_unshift($xactions, $xaction);
 
     return $xactions;
   }
 
   protected function shouldImplyCC(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     return $xaction->isCommentTransaction();
   }
 
 
 /* -(  Sending Mail  )------------------------------------------------------- */
 
 
   /**
    * @task mail
    */
   protected function shouldSendMail(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return false;
   }
 
 
   /**
    * @task mail
    */
   protected function sendMail(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $email_to = array_filter(array_unique($this->getMailTo($object)));
     $email_cc = array_filter(array_unique($this->getMailCC($object)));
 
     $phids = array_merge($email_to, $email_cc);
     $handles = id(new PhabricatorHandleQuery())
       ->setViewer($this->requireActor())
       ->withPHIDs($phids)
       ->execute();
 
     $template = $this->buildMailTemplate($object);
     $body = $this->buildMailBody($object, $xactions);
 
     $mail_tags = $this->getMailTags($object, $xactions);
 
     $action = $this->getStrongestAction($object, $xactions)->getActionName();
 
     $template
       ->setFrom($this->requireActor()->getPHID())
       ->setSubjectPrefix($this->getMailSubjectPrefix())
       ->setVarySubjectPrefix('['.$action.']')
       ->setThreadID($this->getMailThreadID($object), $this->getIsNewObject())
       ->setRelatedPHID($object->getPHID())
       ->setExcludeMailRecipientPHIDs($this->getExcludeMailRecipientPHIDs())
       ->setMailTags($mail_tags)
       ->setIsBulk(true)
       ->setBody($body->render());
 
     if ($this->getParentMessageID()) {
       $template->setParentMessageID($this->getParentMessageID());
     }
 
     $mails = $this
       ->buildReplyHandler($object)
       ->multiplexMail(
         $template,
         array_select_keys($handles, $email_to),
         array_select_keys($handles, $email_cc));
 
     foreach ($mails as $mail) {
       $mail->saveAndSend();
     }
 
     $template->addTos($email_to);
     $template->addCCs($email_cc);
 
     return $template;
   }
 
   protected function getMailThreadID(PhabricatorLiskDAO $object) {
     return $object->getPHID();
   }
 
 
   /**
    * @task mail
    */
   protected function getStrongestAction(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return last(msort($xactions, 'getActionStrength'));
   }
 
 
   /**
    * @task mail
    */
   protected function buildReplyHandler(PhabricatorLiskDAO $object) {
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function getMailSubjectPrefix() {
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function getMailTags(
     PhabricatorLiskDAO $object,
     array $xactions) {
     $tags = array();
 
     foreach ($xactions as $xaction) {
       $tags[] = $xaction->getMailTags();
     }
 
     return array_mergev($tags);
   }
 
 
   /**
    * @task mail
    */
   protected function buildMailTemplate(PhabricatorLiskDAO $object) {
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function getMailTo(PhabricatorLiskDAO $object) {
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function getMailCC(PhabricatorLiskDAO $object) {
     if ($object instanceof PhabricatorSubscribableInterface) {
       return $this->subscribers;
     }
     throw new Exception("Capability not supported.");
   }
 
 
   /**
    * @task mail
    */
   protected function buildMailBody(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $headers = array();
     $comments = array();
 
     foreach ($xactions as $xaction) {
       if ($xaction->shouldHideForMail($xactions)) {
         continue;
       }
 
       $header = $xaction->getTitleForMail();
       if ($header !== null) {
         $headers[] = $header;
       }
 
       $comment = $xaction->getBodyForMail();
       if ($comment !== null) {
         $comments[] = $comment;
       }
     }
 
     $body = new PhabricatorMetaMTAMailBody();
     $body->addRawSection(implode("\n", $headers));
 
     foreach ($comments as $comment) {
       $body->addRawSection($comment);
     }
 
     return $body;
   }
 
 
 /* -(  Publishing Feed Stories  )-------------------------------------------- */
 
 
   /**
    * @task feed
    */
   protected function supportsFeed() {
     return false;
   }
 
 
   /**
    * @task feed
    */
   protected function getFeedStoryType() {
     return 'PhabricatorApplicationTransactionFeedStory';
   }
 
 
   /**
    * @task feed
    */
   protected function getFeedRelatedPHIDs(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     return array(
       $object->getPHID(),
       $this->requireActor()->getPHID(),
     );
   }
 
 
   /**
    * @task feed
    */
   protected function getFeedNotifyPHIDs(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     return array_unique(array_merge(
       $this->getMailTo($object),
       $this->getMailCC($object)));
   }
 
 
   /**
    * @task feed
    */
   protected function getFeedStoryData(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $xactions = msort($xactions, 'getActionStrength');
     $xactions = array_reverse($xactions);
 
     return array(
       'objectPHID'        => $object->getPHID(),
       'transactionPHIDs'  => mpull($xactions, 'getPHID'),
     );
   }
 
 
   /**
    * @task feed
    */
   protected function publishFeedStory(
     PhabricatorLiskDAO $object,
     array $xactions,
     array $mailed_phids) {
 
     $related_phids = $this->getFeedRelatedPHIDs($object, $xactions);
     $subscribed_phids = $this->getFeedNotifyPHIDs($object, $xactions);
 
     $story_type = $this->getFeedStoryType();
     $story_data = $this->getFeedStoryData($object, $xactions);
 
     id(new PhabricatorFeedStoryPublisher())
       ->setStoryType($story_type)
       ->setStoryData($story_data)
       ->setStoryTime(time())
       ->setStoryAuthorPHID($this->requireActor()->getPHID())
       ->setRelatedPHIDs($related_phids)
       ->setPrimaryObjectPHID($object->getPHID())
       ->setSubscribedPHIDs($subscribed_phids)
       ->setMailRecipientPHIDs($mailed_phids)
       ->publish();
   }
 
 
 /* -(  Search Index  )------------------------------------------------------- */
 
 
   /**
    * @task search
    */
   protected function supportsSearch() {
     return false;
   }
 
 
 /* -(  Herald Integration )-------------------------------------------------- */
 
 
   protected function supportsHerald() {
     return false;
   }
 
   protected function buildHeraldAdapter(
     PhabricatorLiskDAO $object,
     array $xactions) {
     throw new Exception('No herald adapter specified.');
   }
 
   private function setHeraldAdapter(HeraldAdapter $adapter) {
     $this->heraldAdapter = $adapter;
     return $this;
   }
 
   protected function getHeraldAdapter() {
     return $this->heraldAdapter;
   }
 
   private function setHeraldTranscript(HeraldTranscript $transcript) {
     $this->heraldTranscript = $transcript;
     return $this;
   }
 
   protected function getHeraldTranscript() {
     return $this->heraldTranscript;
   }
 
   private function applyHeraldRules(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $adapter = $this->buildHeraldAdapter($object, $xactions);
     $adapter->setContentSource($this->getContentSource());
     $adapter->setIsNewObject($this->getIsNewObject());
     $xscript = HeraldEngine::loadAndApplyRules($adapter);
 
     $this->setHeraldAdapter($adapter);
     $this->setHeraldTranscript($xscript);
 
     $this->didApplyHeraldRules($object, $adapter, $xscript);
   }
 
   protected function didApplyHeraldRules(
     PhabricatorLiskDAO $object,
     HeraldAdapter $adapter,
     HeraldTranscript $transcript) {
 
   }
 
 
 /* -(  Custom Fields  )------------------------------------------------------ */
 
 
   /**
    * @task customfield
    */
   private function getCustomFieldForTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
 
     $field_key = $xaction->getMetadataValue('customfield:key');
     if (!$field_key) {
       throw new Exception(
         "Custom field transaction has no 'customfield:key'!");
     }
 
     $field = PhabricatorCustomField::getObjectField(
       $object,
       PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS,
       $field_key);
 
     if (!$field) {
       throw new Exception(
         "Custom field transaction has invalid 'customfield:key'; field ".
         "'{$field_key}' is disabled or does not exist.");
     }
 
     if (!$field->shouldAppearInApplicationTransactions()) {
       throw new Exception(
         "Custom field transaction '{$field_key}' does not implement ".
         "integration for ApplicationTransactions.");
     }
 
     $field->setViewer($this->getActor());
 
     return $field;
   }
 
 
 /* -(  Files  )-------------------------------------------------------------- */
 
 
   /**
    * Extract the PHIDs of any files which these transactions attach.
    *
    * @task files
    */
   private function extractFilePHIDs(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $blocks = array();
     foreach ($xactions as $xaction) {
       $blocks[] = $this->getRemarkupBlocksFromTransaction($xaction);
     }
     $blocks = array_mergev($blocks);
 
     $phids = array();
     if ($blocks) {
       $phids[] = PhabricatorMarkupEngine::extractFilePHIDsFromEmbeddedFiles(
         $blocks);
     }
 
     foreach ($xactions as $xaction) {
       $phids[] = $this->extractFilePHIDsFromCustomTransaction(
         $object,
         $xaction);
     }
 
     $phids = array_unique(array_filter(array_mergev($phids)));
     if (!$phids) {
       return array();
     }
 
     // Only let a user attach files they can actually see, since this would
     // otherwise let you access any file by attaching it to an object you have
     // view permission on.
 
     $files = id(new PhabricatorFileQuery())
       ->setViewer($this->getActor())
       ->withPHIDs($phids)
       ->execute();
 
     return mpull($files, 'getPHID');
   }
 
   /**
    * @task files
    */
   protected function extractFilePHIDsFromCustomTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
     return array();
   }
 
 
   /**
    * @task files
    */
   private function attachFiles(
     PhabricatorLiskDAO $object,
     array $file_phids) {
 
     if (!$file_phids) {
       return;
     }
 
     $editor = id(new PhabricatorEdgeEditor())
       ->setActor($this->getActor());
 
     // TODO: Edge-based events were almost certainly a terrible idea. If we
     // don't suppress this event, the Maniphest listener reenters and adds
     // more transactions. Just suppress it until that can get cleaned up.
     $editor->setSuppressEvents(true);
 
     $src = $object->getPHID();
     $type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_FILE;
     foreach ($file_phids as $dst) {
       $editor->addEdge($src, $type, $dst);
     }
 
     $editor->save();
   }
 
 }
diff --git a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
index 151f346f06..047a862c77 100644
--- a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
+++ b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
@@ -1,750 +1,758 @@
 <?php
 
 abstract class PhabricatorApplicationTransaction
   extends PhabricatorLiskDAO
   implements PhabricatorPolicyInterface {
 
   const TARGET_TEXT = 'text';
   const TARGET_HTML = 'html';
 
   protected $phid;
   protected $objectPHID;
   protected $authorPHID;
   protected $viewPolicy;
   protected $editPolicy;
 
   protected $commentPHID;
   protected $commentVersion = 0;
   protected $transactionType;
   protected $oldValue;
   protected $newValue;
   protected $metadata = array();
 
   protected $contentSource;
 
   private $comment;
   private $commentNotLoaded;
 
   private $handles;
   private $renderingTarget = self::TARGET_HTML;
   private $transactionGroup = array();
   private $viewer = self::ATTACHABLE;
   private $object = self::ATTACHABLE;
 
   private $ignoreOnNoEffect;
 
 
   /**
    * Flag this transaction as a pure side-effect which should be ignored when
    * applying transactions if it has no effect, even if transaction application
    * would normally fail. This both provides users with better error messages
    * and allows transactions to perform optional side effects.
    */
   public function setIgnoreOnNoEffect($ignore) {
     $this->ignoreOnNoEffect = $ignore;
     return $this;
   }
 
   public function getIgnoreOnNoEffect() {
     return $this->ignoreOnNoEffect;
   }
 
+  public function shouldGenerateOldValue() {
+    switch ($this->getTransactionType()) {
+      case PhabricatorTransactions::TYPE_CUSTOMFIELD:
+        return false;
+    }
+    return true;
+  }
+
   abstract public function getApplicationTransactionType();
 
   private function getApplicationObjectTypeName() {
     $types = PhabricatorPHIDType::getAllTypes();
 
     $type = idx($types, $this->getApplicationTransactionType());
     if ($type) {
       return $type->getTypeName();
     }
 
     return pht('Object');
   }
 
   public function getApplicationTransactionCommentObject() {
     throw new Exception("Not implemented!");
   }
 
   public function getApplicationTransactionViewObject() {
     return new PhabricatorApplicationTransactionView();
   }
 
   public function getMetadataValue($key, $default = null) {
     return idx($this->metadata, $key, $default);
   }
 
   public function setMetadataValue($key, $value) {
     $this->metadata[$key] = $value;
     return $this;
   }
 
   public function generatePHID() {
     $type = PhabricatorApplicationTransactionPHIDTypeTransaction::TYPECONST;
     $subtype = $this->getApplicationTransactionType();
 
     return PhabricatorPHID::generateNewPHID($type, $subtype);
   }
 
   public function getConfiguration() {
     return array(
       self::CONFIG_AUX_PHID => true,
       self::CONFIG_SERIALIZATION => array(
         'oldValue' => self::SERIALIZATION_JSON,
         'newValue' => self::SERIALIZATION_JSON,
         'metadata' => self::SERIALIZATION_JSON,
       ),
     ) + parent::getConfiguration();
   }
 
   public function setContentSource(PhabricatorContentSource $content_source) {
     $this->contentSource = $content_source->serialize();
     return $this;
   }
 
   public function getContentSource() {
     return PhabricatorContentSource::newFromSerialized($this->contentSource);
   }
 
   public function hasComment() {
     return $this->getComment() && strlen($this->getComment()->getContent());
   }
 
   public function getComment() {
     if ($this->commentNotLoaded) {
       throw new Exception("Comment for this transaction was not loaded.");
     }
     return $this->comment;
   }
 
   public function attachComment(
     PhabricatorApplicationTransactionComment $comment) {
     $this->comment = $comment;
     $this->commentNotLoaded = false;
     return $this;
   }
 
   public function setCommentNotLoaded($not_loaded) {
     $this->commentNotLoaded = $not_loaded;
     return $this;
   }
 
   public function attachObject($object) {
     $this->object = $object;
     return $this;
   }
 
   public function getObject() {
     return $this->assertAttached($this->object);
   }
 
   public function getRemarkupBlocks() {
     $blocks = array();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           $custom_blocks = $field->getApplicationTransactionRemarkupBlocks(
             $this);
           foreach ($custom_blocks as $custom_block) {
             $blocks[] = $custom_block;
           }
         }
         break;
     }
 
     if ($this->getComment()) {
       $blocks[] = $this->getComment()->getContent();
     }
 
     return $blocks;
   }
 
 
 /* -(  Rendering  )---------------------------------------------------------- */
 
   public function setRenderingTarget($rendering_target) {
     $this->renderingTarget = $rendering_target;
     return $this;
   }
 
   public function getRenderingTarget() {
     return $this->renderingTarget;
   }
 
   public function attachViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
     return $this;
   }
 
   public function getViewer() {
     return $this->assertAttached($this->viewer);
   }
 
   public function getRequiredHandlePHIDs() {
     $phids = array();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     $phids[] = array($this->getAuthorPHID());
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           $phids[] = $field->getApplicationTransactionRequiredHandlePHIDs(
             $this);
         }
         break;
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $phids[] = $old;
         $phids[] = $new;
         break;
       case PhabricatorTransactions::TYPE_EDGE:
         $phids[] = ipull($old, 'dst');
         $phids[] = ipull($new, 'dst');
         break;
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         if (!PhabricatorPolicyQuery::isGlobalPolicy($old)) {
           $phids[] = array($old);
         }
         if (!PhabricatorPolicyQuery::isGlobalPolicy($new)) {
           $phids[] = array($new);
         }
         break;
     }
 
     return array_mergev($phids);
   }
 
   public function setHandles(array $handles) {
     $this->handles = $handles;
     return $this;
   }
 
   public function getHandle($phid) {
     if (empty($this->handles[$phid])) {
       throw new Exception(
         pht(
           'Transaction ("%s") requires a handle ("%s") that it did not '.
           'load.',
           $this->getPHID(),
           $phid));
     }
     return $this->handles[$phid];
   }
 
   public function getHandleIfExists($phid) {
     return idx($this->handles, $phid);
   }
 
   public function getHandles() {
     if ($this->handles === null) {
       throw new Exception(
         'Transaction requires handles and it did not load them.'
       );
     }
     return $this->handles;
   }
 
   public function renderHandleLink($phid) {
     if ($this->renderingTarget == self::TARGET_HTML) {
       return $this->getHandle($phid)->renderLink();
     } else {
       return $this->getHandle($phid)->getLinkName();
     }
   }
 
   public function renderHandleList(array $phids) {
     $links = array();
     foreach ($phids as $phid) {
       $links[] = $this->renderHandleLink($phid);
     }
     if ($this->renderingTarget == self::TARGET_HTML) {
       return phutil_implode_html(', ', $links);
     } else {
       return implode(', ', $links);
     }
   }
 
   public function renderPolicyName($phid) {
     $policy = PhabricatorPolicy::newFromPolicyAndHandle(
       $phid,
       $this->getHandleIfExists($phid));
     if ($this->renderingTarget == self::TARGET_HTML) {
       $output = $policy->renderDescription();
     } else {
       $output = hsprintf('%s', $policy->getFullName());
     }
     return $output;
   }
 
   public function getIcon() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return 'comment';
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return 'message';
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return 'lock';
       case PhabricatorTransactions::TYPE_EDGE:
         return 'link';
     }
 
     return 'edit';
   }
 
   public function getColor() {
     return null;
   }
 
   protected function getTransactionCustomField() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $key = $this->getMetadataValue('customfield:key');
         if (!$key) {
           return null;
         }
 
         $field = PhabricatorCustomField::getObjectField(
           $this->getObject(),
           PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS,
           $key);
         if (!$field) {
           return null;
         }
 
         $field->setViewer($this->getViewer());
         return $field;
     }
 
     return null;
   }
 
   public function shouldHide() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         if ($this->getOldValue() === null) {
           return true;
         } else {
           return false;
         }
         break;
     }
 
     return false;
   }
 
   public function shouldHideForMail(array $xactions) {
     return $this->shouldHide();
   }
 
   public function getTitleForMail() {
     return id(clone $this)->setRenderingTarget('text')->getTitle();
   }
 
   public function getBodyForMail() {
     $comment = $this->getComment();
     if ($comment && strlen($comment->getContent())) {
       return $comment->getContent();
     }
     return null;
   }
 
   public function getNoEffectDescription() {
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht('You can not post an empty comment.');
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         return pht(
           'This %s already has that view policy.',
           $this->getApplicationObjectTypeName());
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         return pht(
           'This %s already has that edit policy.',
           $this->getApplicationObjectTypeName());
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return pht(
           'This %s already has that join policy.',
           $this->getApplicationObjectTypeName());
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return pht(
           'All users are already subscribed to this %s.',
           $this->getApplicationObjectTypeName());
       case PhabricatorTransactions::TYPE_EDGE:
         return pht('Edges already exist; transaction has no effect.');
     }
 
     return pht('Transaction has no effect.');
   }
 
   public function getTitle() {
     $author_phid = $this->getAuthorPHID();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht(
           '%s added a comment.',
           $this->renderHandleLink($author_phid));
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         return pht(
           '%s changed the visibility of this %s from "%s" to "%s".',
           $this->renderHandleLink($author_phid),
           $this->getApplicationObjectTypeName(),
           $this->renderPolicyName($old),
           $this->renderPolicyName($new));
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         return pht(
           '%s changed the edit policy of this %s from "%s" to "%s".',
           $this->renderHandleLink($author_phid),
           $this->getApplicationObjectTypeName(),
           $this->renderPolicyName($old),
           $this->renderPolicyName($new));
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return pht(
           '%s changed the join policy of this %s from "%s" to "%s".',
           $this->renderHandleLink($author_phid),
           $this->getApplicationObjectTypeName(),
           $this->renderPolicyName($old),
           $this->renderPolicyName($new));
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $add = array_diff($new, $old);
         $rem = array_diff($old, $new);
 
         if ($add && $rem) {
           return pht(
             '%s edited subscriber(s), added %d: %s; removed %d: %s.',
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderHandleList($add),
             count($rem),
             $this->renderHandleList($rem));
         } else if ($add) {
           return pht(
             '%s added %d subscriber(s): %s.',
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderHandleList($add));
         } else if ($rem) {
           return pht(
             '%s removed %d subscriber(s): %s.',
             $this->renderHandleLink($author_phid),
             count($rem),
             $this->renderHandleList($rem));
         } else {
           // This is used when rendering previews, before the user actually
           // selects any CCs.
           return pht(
             '%s updated subscribers...',
             $this->renderHandleLink($author_phid));
         }
         break;
       case PhabricatorTransactions::TYPE_EDGE:
         $new = ipull($new, 'dst');
         $old = ipull($old, 'dst');
         $add = array_diff($new, $old);
         $rem = array_diff($old, $new);
         $type = $this->getMetadata('edge:type');
         $type = head($type);
 
         if ($add && $rem) {
           $string = PhabricatorEdgeConfig::getEditStringForEdgeType($type);
           return pht(
             $string,
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderHandleList($add),
             count($rem),
             $this->renderHandleList($rem));
         } else if ($add) {
           $string = PhabricatorEdgeConfig::getAddStringForEdgeType($type);
           return pht(
             $string,
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderHandleList($add));
         } else if ($rem) {
           $string = PhabricatorEdgeConfig::getRemoveStringForEdgeType($type);
           return pht(
             $string,
             $this->renderHandleLink($author_phid),
             count($rem),
             $this->renderHandleList($rem));
         } else {
           return pht(
             '%s edited edge metadata.',
             $this->renderHandleLink($author_phid));
         }
 
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionTitle($this);
         } else {
           return pht(
             '%s edited a custom field.',
             $this->renderHandleLink($author_phid));
         }
 
       default:
         return pht(
           '%s edited this %s.',
           $this->renderHandleLink($author_phid),
           $this->getApplicationObjectTypeName());
     }
   }
 
   public function getTitleForFeed(PhabricatorFeedStory $story) {
     $author_phid = $this->getAuthorPHID();
     $object_phid = $this->getObjectPHID();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht(
           '%s added a comment to %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         return pht(
           '%s changed the visibility for %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         return pht(
           '%s changed the edit policy for %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return pht(
           '%s changed the join policy for %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return pht(
           '%s updated subscribers of %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_EDGE:
         $type = $this->getMetadata('edge:type');
         $type = head($type);
         $string = PhabricatorEdgeConfig::getFeedStringForEdgeType($type);
         return pht(
           $string,
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionTitleForFeed($this, $story);
         } else {
           return pht(
             '%s edited a custom field on %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid));
         }
 
     }
 
     return $this->getTitle();
   }
 
   public function getBodyForFeed(PhabricatorFeedStory $story) {
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     $body = null;
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         $text = $this->getComment()->getContent();
         $body = phutil_escape_html_newlines(
           phutil_utf8_shorten($text, 128));
         break;
     }
     return $body;
   }
 
   public function getActionStrength() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return 0.5;
     }
     return 1.0;
   }
 
   public function isCommentTransaction() {
     if ($this->hasComment()) {
       return true;
     }
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return true;
     }
 
     return false;
   }
 
   public function getActionName() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht('Commented On');
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return pht('Changed Policy');
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return pht('Changed Subscribers');
       default:
         return pht('Updated');
     }
   }
 
   public function getMailTags() {
     return array();
   }
 
   public function hasChangeDetails() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionHasChangeDetails($this);
         }
         break;
     }
     return false;
   }
 
   public function renderChangeDetails(PhabricatorUser $viewer) {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionChangeDetails($this, $viewer);
         }
         break;
     }
 
     return $this->renderTextCorpusChangeDetails();
   }
 
   public function renderTextCorpusChangeDetails(
     PhabricatorUser $viewer,
     $old,
     $new) {
 
     require_celerity_resource('differential-changeset-view-css');
 
     $view = id(new PhabricatorApplicationTransactionTextDiffDetailView())
       ->setUser($viewer)
       ->setOldText($old)
       ->setNewText($new);
 
     return $view->render();
   }
 
   public function attachTransactionGroup(array $group) {
     assert_instances_of($group, 'PhabricatorApplicationTransaction');
     $this->transactionGroup = $group;
     return $this;
   }
 
   public function getTransactionGroup() {
     return $this->transactionGroup;
   }
 
   /**
    * Should this transaction be visually grouped with an existing transaction
    * group?
    *
    * @param list<PhabricatorApplicationTransaction> List of transactions.
    * @return bool True to display in a group with the other transactions.
    */
   public function shouldDisplayGroupWith(array $group) {
     $this_source = null;
     if ($this->getContentSource()) {
       $this_source = $this->getContentSource()->getSource();
     }
 
     foreach ($group as $xaction) {
       // Don't group transactions by different authors.
       if ($xaction->getAuthorPHID() != $this->getAuthorPHID()) {
         return false;
       }
 
       // Don't group transactions for different objects.
       if ($xaction->getObjectPHID() != $this->getObjectPHID()) {
         return false;
       }
 
       // Don't group anything into a group which already has a comment.
       if ($xaction->isCommentTransaction()) {
         return false;
       }
 
       // Don't group transactions from different content sources.
       $other_source = null;
       if ($xaction->getContentSource()) {
         $other_source = $xaction->getContentSource()->getSource();
       }
 
       if ($other_source != $this_source) {
         return false;
       }
 
       // Don't group transactions which happened more than 2 minutes apart.
       $apart = abs($xaction->getDateCreated() - $this->getDateCreated());
       if ($apart > (60 * 2)) {
         return false;
       }
     }
 
     return true;
   }
 
 
 /* -(  PhabricatorPolicyInterface Implementation  )-------------------------- */
 
 
   public function getCapabilities() {
     return array(
       PhabricatorPolicyCapability::CAN_VIEW,
       PhabricatorPolicyCapability::CAN_EDIT,
     );
   }
 
   public function getPolicy($capability) {
     switch ($capability) {
       case PhabricatorPolicyCapability::CAN_VIEW:
         return $this->getViewPolicy();
       case PhabricatorPolicyCapability::CAN_EDIT:
         return $this->getEditPolicy();
     }
   }
 
   public function hasAutomaticCapability($capability, PhabricatorUser $viewer) {
     return ($viewer->getPHID() == $this->getAuthorPHID());
   }
 
   public function describeAutomaticCapability($capability) {
     // TODO: (T603) Exact policies are unclear here.
     return null;
   }
 
 
 }
diff --git a/webroot/rsrc/js/application/projects/behavior-project-boards.js b/webroot/rsrc/js/application/projects/behavior-project-boards.js
index 478f950d14..55a1e02700 100644
--- a/webroot/rsrc/js/application/projects/behavior-project-boards.js
+++ b/webroot/rsrc/js/application/projects/behavior-project-boards.js
@@ -1,66 +1,69 @@
 /**
  * @provides javelin-behavior-project-boards
  * @requires javelin-behavior
  *           javelin-dom
  *           javelin-util
  *           javelin-stratcom
  *           javelin-workflow
  *           phabricator-draggable-list
  */
 
 JX.behavior('project-boards', function(config) {
 
   function finditems(col) {
     return JX.DOM.scry(col, 'li', 'project-card');
   }
 
   function onupdate(node) {
     JX.DOM.alterClass(node, 'project-column-empty', !this.findItems().length);
   }
 
   function onresponse(response) {
 
   }
 
   function ondrop(list, item, after, from) {
     list.lock();
     JX.DOM.alterClass(item, 'drag-sending', true);
 
     var data = {
       objectPHID: JX.Stratcom.getData(item).objectPHID,
-      columnPHID: JX.Stratcom.getData(list.getRootNode()).columnPHID,
-      afterPHID: after && JX.Stratcom.getData(after).objectPHID
+      columnPHID: JX.Stratcom.getData(list.getRootNode()).columnPHID
     };
 
+    if (after) {
+      data.afterPHID = JX.Stratcom.getData(after).objectPHID;
+    }
+
     var workflow = new JX.Workflow(config.moveURI, data)
       .setHandler(function(response) {
         onresponse(response);
         list.unlock();
 
         JX.DOM.alterClass(item, 'drag-sending', false);
       });
 
     workflow.start();
   }
 
   var lists = [];
   var ii;
   var cols = JX.DOM.scry(JX.$(config.boardID), 'ul', 'project-column');
 
   for (ii = 0; ii < cols.length; ii++) {
     var list = new JX.DraggableList('project-card', cols[ii])
       .setFindItemsHandler(JX.bind(null, finditems, cols[ii]));
 
     list.listen('didSend', JX.bind(list, onupdate, cols[ii]));
     list.listen('didReceive', JX.bind(list, onupdate, cols[ii]));
 
     list.listen('didDrop', JX.bind(null, ondrop, list));
 
     lists.push(list);
   }
 
   for (ii = 0; ii < lists.length; ii++) {
     lists[ii].setGroup(lists);
   }
 
 });