diff --git a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
index ee8a7a47a3..071b94a933 100644
--- a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
+++ b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
@@ -1,1427 +1,1533 @@
 <?php
 
 abstract class PhabricatorApplicationTransaction
   extends PhabricatorLiskDAO
   implements
     PhabricatorPolicyInterface,
     PhabricatorDestructibleInterface {
 
   const TARGET_TEXT = 'text';
   const TARGET_HTML = 'html';
 
   protected $phid;
   protected $objectPHID;
   protected $authorPHID;
   protected $viewPolicy;
   protected $editPolicy;
 
   protected $commentPHID;
   protected $commentVersion = 0;
   protected $transactionType;
   protected $oldValue;
   protected $newValue;
   protected $metadata = array();
 
   protected $contentSource;
 
   private $comment;
   private $commentNotLoaded;
 
   private $handles;
   private $renderingTarget = self::TARGET_HTML;
   private $transactionGroup = array();
   private $viewer = self::ATTACHABLE;
   private $object = self::ATTACHABLE;
   private $oldValueHasBeenSet = false;
 
   private $ignoreOnNoEffect;
 
 
   /**
    * Flag this transaction as a pure side-effect which should be ignored when
    * applying transactions if it has no effect, even if transaction application
    * would normally fail. This both provides users with better error messages
    * and allows transactions to perform optional side effects.
    */
   public function setIgnoreOnNoEffect($ignore) {
     $this->ignoreOnNoEffect = $ignore;
     return $this;
   }
 
   public function getIgnoreOnNoEffect() {
     return $this->ignoreOnNoEffect;
   }
 
   public function shouldGenerateOldValue() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_BUILDABLE:
       case PhabricatorTransactions::TYPE_TOKEN:
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
       case PhabricatorTransactions::TYPE_INLINESTATE:
         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 PhutilMethodNotImplementedException();
   }
 
   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 = PhabricatorApplicationTransactionTransactionPHIDType::TYPECONST;
     $subtype = $this->getApplicationTransactionType();
 
     return PhabricatorPHID::generateNewPHID($type, $subtype);
   }
 
   protected 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,
       ),
       self::CONFIG_COLUMN_SCHEMA => array(
         'commentPHID' => 'phid?',
         'commentVersion' => 'uint32',
         'contentSource' => 'text',
         'transactionType' => 'text32',
       ),
       self::CONFIG_KEY_SCHEMA => array(
         'key_object' => array(
           'columns' => array('objectPHID'),
         ),
       ),
     ) + 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(pht('Comment for this transaction was not loaded.'));
     }
     return $this->comment;
   }
 
   public function setIsCreateTransaction($create) {
     return $this->setMetadataValue('core.create', $create);
   }
 
   public function getIsCreateTransaction() {
     return (bool)$this->getMetadataValue('core.create', false);
   }
 
   public function setIsDefaultTransaction($default) {
     return $this->setMetadataValue('core.default', $default);
   }
 
   public function getIsDefaultTransaction() {
     return (bool)$this->getMetadataValue('core.default', false);
   }
 
   public function attachComment(
     PhabricatorApplicationTransactionComment $comment) {
     $this->comment = $comment;
     $this->commentNotLoaded = false;
     return $this;
   }
 
   public function setCommentNotLoaded($not_loaded) {
     $this->commentNotLoaded = $not_loaded;
     return $this;
   }
 
   public function attachObject($object) {
     $this->object = $object;
     return $this;
   }
 
   public function getObject() {
     return $this->assertAttached($this->object);
   }
 
   public function getRemarkupBlocks() {
     $blocks = array();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           $custom_blocks = $field->getApplicationTransactionRemarkupBlocks(
             $this);
           foreach ($custom_blocks as $custom_block) {
             $blocks[] = $custom_block;
           }
         }
         break;
     }
 
     if ($this->getComment()) {
       $blocks[] = $this->getComment()->getContent();
     }
 
     return $blocks;
   }
 
   public function setOldValue($value) {
     $this->oldValueHasBeenSet = true;
     $this->writeField('oldValue', $value);
     return $this;
   }
 
   public function hasOldValue() {
     return $this->oldValueHasBeenSet;
   }
 
 
 /* -(  Rendering  )---------------------------------------------------------- */
 
   public function setRenderingTarget($rendering_target) {
     $this->renderingTarget = $rendering_target;
     return $this;
   }
 
   public function getRenderingTarget() {
     return $this->renderingTarget;
   }
 
   public function attachViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
     return $this;
   }
 
   public function getViewer() {
     return $this->assertAttached($this->viewer);
   }
 
   public function getRequiredHandlePHIDs() {
     $phids = array();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     $phids[] = array($this->getAuthorPHID());
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           $phids[] = $field->getApplicationTransactionRequiredHandlePHIDs(
             $this);
         }
         break;
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $phids[] = $old;
         $phids[] = $new;
         break;
       case PhabricatorTransactions::TYPE_EDGE:
         $phids[] = ipull($old, 'dst');
         $phids[] = ipull($new, 'dst');
         break;
+      case PhabricatorTransactions::TYPE_COLUMNS:
+        foreach ($new as $move) {
+          $phids[] = array(
+            $move['columnPHID'],
+            $move['boardPHID'],
+          );
+          $phids[] = $move['fromColumnPHIDs'];
+        }
+        break;
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         if (!PhabricatorPolicyQuery::isSpecialPolicy($old)) {
           $phids[] = array($old);
         }
         if (!PhabricatorPolicyQuery::isSpecialPolicy($new)) {
           $phids[] = array($new);
         }
         break;
       case PhabricatorTransactions::TYPE_SPACE:
         if ($old) {
           $phids[] = array($old);
         }
         if ($new) {
           $phids[] = array($new);
         }
         break;
       case PhabricatorTransactions::TYPE_TOKEN:
         break;
       case PhabricatorTransactions::TYPE_BUILDABLE:
         $phid = $this->getMetadataValue('harbormaster:buildablePHID');
         if ($phid) {
           $phids[] = array($phid);
         }
         break;
     }
 
     if ($this->getComment()) {
       $phids[] = array($this->getComment()->getAuthorPHID());
     }
 
     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", of type "%s") requires a handle ("%s") that it '.
           'did not load.',
           $this->getPHID(),
           $this->getTransactionType(),
           $phid));
     }
     return $this->handles[$phid];
   }
 
   public function getHandleIfExists($phid) {
     return idx($this->handles, $phid);
   }
 
   public function getHandles() {
     if ($this->handles === null) {
       throw new Exception(
         pht('Transaction requires handles and it did not load them.'));
     }
     return $this->handles;
   }
 
   public function renderHandleLink($phid) {
     if ($this->renderingTarget == self::TARGET_HTML) {
       return $this->getHandle($phid)->renderLink();
     } else {
       return $this->getHandle($phid)->getLinkName();
     }
   }
 
   public function renderHandleList(array $phids) {
     $links = array();
     foreach ($phids as $phid) {
       $links[] = $this->renderHandleLink($phid);
     }
     if ($this->renderingTarget == self::TARGET_HTML) {
       return phutil_implode_html(', ', $links);
     } else {
       return implode(', ', $links);
     }
   }
 
   private function renderSubscriberList(array $phids, $change_type) {
     if ($this->getRenderingTarget() == self::TARGET_TEXT) {
       return $this->renderHandleList($phids);
     } else {
       $handles = array_select_keys($this->getHandles(), $phids);
       return id(new SubscriptionListStringBuilder())
         ->setHandles($handles)
         ->setObjectPHID($this->getPHID())
         ->buildTransactionString($change_type);
     }
   }
 
   protected function renderPolicyName($phid, $state = 'old') {
     $policy = PhabricatorPolicy::newFromPolicyAndHandle(
       $phid,
       $this->getHandleIfExists($phid));
     if ($this->renderingTarget == self::TARGET_HTML) {
       switch ($policy->getType()) {
         case PhabricatorPolicyType::TYPE_CUSTOM:
           $policy->setHref('/transactions/'.$state.'/'.$this->getPHID().'/');
           $policy->setWorkflow(true);
           break;
         default:
           break;
       }
       $output = $policy->renderDescription();
     } else {
       $output = hsprintf('%s', $policy->getFullName());
     }
     return $output;
   }
 
   public function getIcon() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         $comment = $this->getComment();
         if ($comment && $comment->getIsRemoved()) {
           return 'fa-trash';
         }
         return 'fa-comment';
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $old = $this->getOldValue();
         $new = $this->getNewValue();
         $add = array_diff($new, $old);
         $rem = array_diff($old, $new);
         if ($add && $rem) {
           return 'fa-user';
         } else if ($add) {
           return 'fa-user-plus';
         } else if ($rem) {
           return 'fa-user-times';
         } else {
           return 'fa-user';
         }
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return 'fa-lock';
       case PhabricatorTransactions::TYPE_EDGE:
         return 'fa-link';
       case PhabricatorTransactions::TYPE_BUILDABLE:
         return 'fa-wrench';
       case PhabricatorTransactions::TYPE_TOKEN:
         return 'fa-trophy';
       case PhabricatorTransactions::TYPE_SPACE:
         return 'fa-th-large';
+      case PhabricatorTransactions::TYPE_COLUMNS:
+        return 'fa-columns';
     }
 
     return 'fa-pencil';
   }
 
   public function getToken() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_TOKEN:
         $old = $this->getOldValue();
         $new = $this->getNewValue();
         if ($new) {
           $icon = substr($new, 10);
         } else {
           $icon = substr($old, 10);
         }
         return array($icon, !$this->getNewValue());
     }
 
     return array(null, null);
   }
 
   public function getColor() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT;
         $comment = $this->getComment();
         if ($comment && $comment->getIsRemoved()) {
           return 'black';
         }
         break;
       case PhabricatorTransactions::TYPE_BUILDABLE:
         switch ($this->getNewValue()) {
           case HarbormasterBuildable::STATUS_PASSED:
             return 'green';
           case HarbormasterBuildable::STATUS_FAILED:
             return 'red';
         }
         break;
     }
     return null;
   }
 
   protected function getTransactionCustomField() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $key = $this->getMetadataValue('customfield:key');
         if (!$key) {
           return null;
         }
 
         $object = $this->getObject();
 
         if (!($object instanceof PhabricatorCustomFieldInterface)) {
           return null;
         }
 
         $field = PhabricatorCustomField::getObjectField(
           $object,
           PhabricatorCustomField::ROLE_APPLICATIONTRANSACTIONS,
           $key);
         if (!$field) {
           return null;
         }
 
         $field->setViewer($this->getViewer());
         return $field;
     }
 
     return null;
   }
 
   public function shouldHide() {
     // Never hide comments.
     if ($this->hasComment()) {
       return false;
     }
 
     // Hide creation transactions if the old value is empty. These are
     // transactions like "alice set the task tile to: ...", which are
     // essentially never interesting.
     if ($this->getIsCreateTransaction()) {
       switch ($this->getTransactionType()) {
         case PhabricatorTransactions::TYPE_CREATE:
         case PhabricatorTransactions::TYPE_VIEW_POLICY:
         case PhabricatorTransactions::TYPE_EDIT_POLICY:
         case PhabricatorTransactions::TYPE_JOIN_POLICY:
         case PhabricatorTransactions::TYPE_SPACE:
+        case PhabricatorTransactions::TYPE_COLUMNS:
           break;
         default:
           $old = $this->getOldValue();
 
           if (is_array($old) && !$old) {
             return true;
           }
 
-          if (!strlen($old)) {
+          if (!is_array($old) && !strlen($old)) {
             return true;
           }
+
           break;
       }
     }
 
     // Hide creation transactions setting values to defaults, even if
     // the old value is not empty. For example, tasks may have a global
     // default view policy of "All Users", but a particular form sets the
     // policy to "Administrators". The transaction corresponding to this
     // change is not interesting, since it is the default behavior of the
     // form.
 
     if ($this->getIsCreateTransaction()) {
       if ($this->getIsDefaultTransaction()) {
         return true;
       }
     }
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
       case PhabricatorTransactions::TYPE_SPACE:
         if ($this->getIsCreateTransaction()) {
           break;
         }
 
         // TODO: Remove this eventually, this is handling old changes during
         // object creation prior to the introduction of "create" and "default"
         // transaction display flags.
 
         // NOTE: We can also hit this case with Space transactions that later
         // update a default space (`null`) to an explicit space, so handling
         // the Space case may require some finesse.
 
         if ($this->getOldValue() === null) {
           return true;
         } else {
           return false;
         }
         break;
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->shouldHideInApplicationTransactions($this);
         }
+      case PhabricatorTransactions::TYPE_COLUMNS:
+        return !$this->getInterestingMoves($this->getNewValue());
       case PhabricatorTransactions::TYPE_EDGE:
         $edge_type = $this->getMetadataValue('edge:type');
         switch ($edge_type) {
           case PhabricatorObjectMentionsObjectEdgeType::EDGECONST:
             return true;
             break;
           case PhabricatorObjectMentionedByObjectEdgeType::EDGECONST:
             $new = ipull($this->getNewValue(), 'dst');
             $old = ipull($this->getOldValue(), 'dst');
             $add = array_diff($new, $old);
             $add_value = reset($add);
             $add_handle = $this->getHandle($add_value);
             if ($add_handle->getPolicyFiltered()) {
               return true;
             }
             return false;
             break;
           default:
             break;
         }
         break;
     }
 
     return false;
   }
 
   public function shouldHideForMail(array $xactions) {
     if ($this->isSelfSubscription()) {
       return true;
     }
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_TOKEN:
         return true;
       case PhabricatorTransactions::TYPE_BUILDABLE:
         switch ($this->getNewValue()) {
           case HarbormasterBuildable::STATUS_FAILED:
             // For now, only ever send mail when builds fail. We might let
             // you customize this later, but in most cases this is probably
             // completely uninteresting.
             return false;
         }
         return true;
      case PhabricatorTransactions::TYPE_EDGE:
         $edge_type = $this->getMetadataValue('edge:type');
         switch ($edge_type) {
           case PhabricatorObjectMentionsObjectEdgeType::EDGECONST:
           case PhabricatorObjectMentionedByObjectEdgeType::EDGECONST:
             return true;
             break;
           default:
             break;
         }
         break;
     }
 
     if ($this->isInlineCommentTransaction()) {
       $inlines = array();
 
       // If there's a normal comment, we don't need to publish the inline
       // transaction, since the normal comment covers things.
       foreach ($xactions as $xaction) {
         if ($xaction->isInlineCommentTransaction()) {
           $inlines[] = $xaction;
           continue;
         }
 
         // We found a normal comment, so hide this inline transaction.
         if ($xaction->hasComment()) {
           return true;
         }
       }
 
       // If there are several inline comments, only publish the first one.
       if ($this !== head($inlines)) {
         return true;
       }
     }
 
     return $this->shouldHide();
   }
 
   public function shouldHideForFeed() {
     if ($this->isSelfSubscription()) {
       return true;
     }
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_TOKEN:
         return true;
       case PhabricatorTransactions::TYPE_BUILDABLE:
         switch ($this->getNewValue()) {
           case HarbormasterBuildable::STATUS_FAILED:
             // For now, don't notify on build passes either. These are pretty
             // high volume and annoying, with very little present value. We
             // might want to turn them back on in the specific case of
             // build successes on the current document?
             return false;
         }
         return true;
      case PhabricatorTransactions::TYPE_EDGE:
         $edge_type = $this->getMetadataValue('edge:type');
         switch ($edge_type) {
           case PhabricatorObjectMentionsObjectEdgeType::EDGECONST:
           case PhabricatorObjectMentionedByObjectEdgeType::EDGECONST:
             return true;
             break;
           default:
             break;
         }
         break;
      case PhabricatorTransactions::TYPE_INLINESTATE:
        return true;
     }
 
     return $this->shouldHide();
   }
 
   public function getTitleForMail() {
     return id(clone $this)->setRenderingTarget('text')->getTitle();
   }
 
   public function getBodyForMail() {
     if ($this->isInlineCommentTransaction()) {
       // We don't return inline comment content as mail body content, because
       // applications need to contextualize it (by adding line numbers, for
       // example) in order for it to make sense.
       return null;
     }
 
     $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_SPACE:
         return pht('This object is already in that space.');
       case PhabricatorTransactions::TYPE_EDGE:
         return pht('Edges already exist; transaction has no effect.');
     }
 
     return pht(
       'Transaction (of type "%s") has no effect.',
       $this->getTransactionType());
   }
 
   public function getTitle() {
     $author_phid = $this->getAuthorPHID();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CREATE:
         return pht(
           '%s created this object.',
           $this->renderHandleLink($author_phid));
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht(
           '%s added a comment.',
           $this->renderHandleLink($author_phid));
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
         if ($this->getIsCreateTransaction()) {
           return pht(
             '%s created this object with visibility "%s".',
             $this->renderHandleLink($author_phid),
             $this->renderPolicyName($new, 'new'));
         } else {
           return pht(
             '%s changed the visibility from "%s" to "%s".',
             $this->renderHandleLink($author_phid),
             $this->renderPolicyName($old, 'old'),
             $this->renderPolicyName($new, 'new'));
         }
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
         if ($this->getIsCreateTransaction()) {
           return pht(
             '%s created this object with edit policy "%s".',
             $this->renderHandleLink($author_phid),
             $this->renderPolicyName($new, 'new'));
         } else {
           return pht(
             '%s changed the edit policy from "%s" to "%s".',
             $this->renderHandleLink($author_phid),
             $this->renderPolicyName($old, 'old'),
             $this->renderPolicyName($new, 'new'));
         }
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         if ($this->getIsCreateTransaction()) {
           return pht(
             '%s created this object with join policy "%s".',
             $this->renderHandleLink($author_phid),
             $this->renderPolicyName($new, 'new'));
         } else {
           return pht(
             '%s changed the join policy from "%s" to "%s".',
             $this->renderHandleLink($author_phid),
             $this->renderPolicyName($old, 'old'),
             $this->renderPolicyName($new, 'new'));
         }
       case PhabricatorTransactions::TYPE_SPACE:
         if ($this->getIsCreateTransaction()) {
           return pht(
             '%s created this object in space %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($new));
         } else {
           return pht(
             '%s shifted this object from the %s space to the %s space.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($old),
             $this->renderHandleLink($new));
         }
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         $add = array_diff($new, $old);
         $rem = array_diff($old, $new);
 
         if ($add && $rem) {
           return pht(
             '%s edited subscriber(s), added %d: %s; removed %d: %s.',
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderSubscriberList($add, 'add'),
             count($rem),
             $this->renderSubscriberList($rem, 'rem'));
         } else if ($add) {
           return pht(
             '%s added %d subscriber(s): %s.',
             $this->renderHandleLink($author_phid),
             count($add),
             $this->renderSubscriberList($add, 'add'));
         } else if ($rem) {
           return pht(
             '%s removed %d subscriber(s): %s.',
             $this->renderHandleLink($author_phid),
             count($rem),
             $this->renderSubscriberList($rem, 'rem'));
         } else {
           // This is used when rendering previews, before the user actually
           // selects any CCs.
           return pht(
             '%s updated subscribers...',
             $this->renderHandleLink($author_phid));
         }
         break;
       case PhabricatorTransactions::TYPE_EDGE:
         $new = ipull($new, 'dst');
         $old = ipull($old, 'dst');
         $add = array_diff($new, $old);
         $rem = array_diff($old, $new);
         $type = $this->getMetadata('edge:type');
         $type = head($type);
 
         $type_obj = PhabricatorEdgeType::getByConstant($type);
 
         if ($add && $rem) {
           return $type_obj->getTransactionEditString(
             $this->renderHandleLink($author_phid),
             new PhutilNumber(count($add) + count($rem)),
             phutil_count($add),
             $this->renderHandleList($add),
             phutil_count($rem),
             $this->renderHandleList($rem));
         } else if ($add) {
           return $type_obj->getTransactionAddString(
             $this->renderHandleLink($author_phid),
             phutil_count($add),
             $this->renderHandleList($add));
         } else if ($rem) {
           return $type_obj->getTransactionRemoveString(
             $this->renderHandleLink($author_phid),
             phutil_count($rem),
             $this->renderHandleList($rem));
         } else {
           return $type_obj->getTransactionPreviewString(
             $this->renderHandleLink($author_phid));
         }
 
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionTitle($this);
         } else {
           return pht(
             '%s edited a custom field.',
             $this->renderHandleLink($author_phid));
         }
 
       case PhabricatorTransactions::TYPE_TOKEN:
         if ($old && $new) {
           return pht(
             '%s updated a token.',
             $this->renderHandleLink($author_phid));
         } else if ($old) {
           return pht(
             '%s rescinded a token.',
             $this->renderHandleLink($author_phid));
         } else {
           return pht(
             '%s awarded a token.',
             $this->renderHandleLink($author_phid));
         }
 
       case PhabricatorTransactions::TYPE_BUILDABLE:
         switch ($this->getNewValue()) {
           case HarbormasterBuildable::STATUS_BUILDING:
             return pht(
               '%s started building %s.',
               $this->renderHandleLink($author_phid),
               $this->renderHandleLink(
                 $this->getMetadataValue('harbormaster:buildablePHID')));
           case HarbormasterBuildable::STATUS_PASSED:
             return pht(
               '%s completed building %s.',
               $this->renderHandleLink($author_phid),
               $this->renderHandleLink(
                 $this->getMetadataValue('harbormaster:buildablePHID')));
           case HarbormasterBuildable::STATUS_FAILED:
             return pht(
               '%s failed to build %s!',
               $this->renderHandleLink($author_phid),
               $this->renderHandleLink(
                 $this->getMetadataValue('harbormaster:buildablePHID')));
           default:
             return null;
         }
 
       case PhabricatorTransactions::TYPE_INLINESTATE:
         $done = 0;
         $undone = 0;
         foreach ($new as $phid => $state) {
           if ($state == PhabricatorInlineCommentInterface::STATE_DONE) {
             $done++;
           } else {
             $undone++;
           }
         }
         if ($done && $undone) {
           return pht(
             '%s marked %s inline comment(s) as done and %s inline comment(s) '.
             'as not done.',
             $this->renderHandleLink($author_phid),
             new PhutilNumber($done),
             new PhutilNumber($undone));
         } else if ($done) {
           return pht(
             '%s marked %s inline comment(s) as done.',
             $this->renderHandleLink($author_phid),
             new PhutilNumber($done));
         } else {
           return pht(
             '%s marked %s inline comment(s) as not done.',
             $this->renderHandleLink($author_phid),
             new PhutilNumber($undone));
         }
         break;
 
+      case PhabricatorTransactions::TYPE_COLUMNS:
+        $moves = $this->getInterestingMoves($new);
+        if (count($moves) == 1) {
+          $move = head($moves);
+          $from_columns = $move['fromColumnPHIDs'];
+          $to_column = $move['columnPHID'];
+          $board_phid = $move['boardPHID'];
+          if (count($from_columns) == 1) {
+            return pht(
+              '%s moved this task from %s to %s on the %s board.',
+              $this->renderHandleLink($author_phid),
+              $this->renderHandleLink(head($from_columns)),
+              $this->renderHandleLink($to_column),
+              $this->renderHandleLink($board_phid));
+          } else {
+            return pht(
+              '%s moved this task to %s on the %s board.',
+              $this->renderHandleLink($author_phid),
+              $this->renderHandleLink($to_column),
+              $this->renderHandleLink($board_phid));
+          }
+        } else {
+          $fragments = array();
+          foreach ($moves as $move) {
+            $fragments[] = pht(
+              '%s (%s)',
+              $this->renderHandleLink($board_phid),
+              $this->renderHandleLink($to_column));
+          }
+
+          return pht(
+            '%s moved this task on %s board(s): %s.',
+            $this->renderHandleLink($author_phid),
+            phutil_count($moves),
+            phutil_implode_html(', ', $fragments));
+        }
+        break;
+
       default:
         return pht(
           '%s edited this %s.',
           $this->renderHandleLink($author_phid),
           $this->getApplicationObjectTypeName());
     }
   }
 
   public function getTitleForFeed() {
     $author_phid = $this->getAuthorPHID();
     $object_phid = $this->getObjectPHID();
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CREATE:
         return pht(
           '%s created %s.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid));
       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_SPACE:
         return pht(
           '%s shifted %s from the %s space to the %s space.',
           $this->renderHandleLink($author_phid),
           $this->renderHandleLink($object_phid),
           $this->renderHandleLink($old),
           $this->renderHandleLink($new));
       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);
 
         $type_obj = PhabricatorEdgeType::getByConstant($type);
 
         if ($add && $rem) {
           return $type_obj->getFeedEditString(
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             new PhutilNumber(count($add) + count($rem)),
             phutil_count($add),
             $this->renderHandleList($add),
             phutil_count($rem),
             $this->renderHandleList($rem));
         } else if ($add) {
           return $type_obj->getFeedAddString(
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             phutil_count($add),
             $this->renderHandleList($add));
         } else if ($rem) {
           return $type_obj->getFeedRemoveString(
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid),
             phutil_count($rem),
             $this->renderHandleList($rem));
         } else {
           return pht(
             '%s edited edge metadata for %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid));
         }
 
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionTitleForFeed($this);
         } else {
           return pht(
             '%s edited a custom field on %s.',
             $this->renderHandleLink($author_phid),
             $this->renderHandleLink($object_phid));
         }
       case PhabricatorTransactions::TYPE_BUILDABLE:
         switch ($this->getNewValue()) {
           case HarbormasterBuildable::STATUS_BUILDING:
             return pht(
               '%s started building %s for %s.',
               $this->renderHandleLink($author_phid),
               $this->renderHandleLink(
                 $this->getMetadataValue('harbormaster:buildablePHID')),
               $this->renderHandleLink($object_phid));
           case HarbormasterBuildable::STATUS_PASSED:
             return pht(
               '%s completed building %s for %s.',
               $this->renderHandleLink($author_phid),
               $this->renderHandleLink(
                 $this->getMetadataValue('harbormaster:buildablePHID')),
               $this->renderHandleLink($object_phid));
           case HarbormasterBuildable::STATUS_FAILED:
             return pht(
               '%s failed to build %s for %s.',
               $this->renderHandleLink($author_phid),
               $this->renderHandleLink(
                 $this->getMetadataValue('harbormaster:buildablePHID')),
               $this->renderHandleLink($object_phid));
           default:
             return null;
         }
 
+      case PhabricatorTransactions::TYPE_COLUMNS:
+        $moves = $this->getInterestingMoves($new);
+        if (count($moves) == 1) {
+          $move = head($moves);
+          $from_columns = $move['fromColumnPHIDs'];
+          $to_column = $move['columnPHID'];
+          $board_phid = $move['boardPHID'];
+          if (count($from_columns) == 1) {
+            return pht(
+              '%s moved %s from %s to %s on the %s board.',
+              $this->renderHandleLink($author_phid),
+              $this->renderHandleLink($object_phid),
+              $this->renderHandleLink(head($from_columns)),
+              $this->renderHandleLink($to_column),
+              $this->renderHandleLink($board_phid));
+          } else {
+            return pht(
+              '%s moved %s to %s on the %s board.',
+              $this->renderHandleLink($author_phid),
+              $this->renderHandleLink($object_phid),
+              $this->renderHandleLink($to_column),
+              $this->renderHandleLink($board_phid));
+          }
+        } else {
+          $fragments = array();
+          foreach ($moves as $move) {
+            $fragments[] = pht(
+              '%s (%s)',
+              $this->renderHandleLink($board_phid),
+              $this->renderHandleLink($to_column));
+          }
+
+          return pht(
+            '%s moved %s on %s board(s): %s.',
+            $this->renderHandleLink($author_phid),
+            $this->renderHandleLink($object_phid),
+            phutil_count($moves),
+            phutil_implode_html(', ', $fragments));
+        }
+        break;
+
     }
 
     return $this->getTitle();
   }
 
   public function getMarkupFieldsForFeed(PhabricatorFeedStory $story) {
     $fields = array();
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         $text = $this->getComment()->getContent();
         if (strlen($text)) {
           $fields[] = 'comment/'.$this->getID();
         }
         break;
     }
 
     return $fields;
   }
 
   public function getMarkupTextForFeed(PhabricatorFeedStory $story, $field) {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         $text = $this->getComment()->getContent();
         return PhabricatorMarkupEngine::summarize($text);
     }
 
     return null;
   }
 
   public function getBodyForFeed(PhabricatorFeedStory $story) {
     $remarkup = $this->getRemarkupBodyForFeed($story);
     if ($remarkup !== null) {
       $remarkup = PhabricatorMarkupEngine::summarize($remarkup);
       return new PHUIRemarkupView($this->viewer, $remarkup);
     }
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     $body = null;
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         $text = $this->getComment()->getContent();
         if (strlen($text)) {
           $body = $story->getMarkupFieldOutput('comment/'.$this->getID());
         }
         break;
     }
 
     return $body;
   }
 
   public function getRemarkupBodyForFeed(PhabricatorFeedStory $story) {
     return null;
   }
 
   public function getActionStrength() {
     if ($this->isInlineCommentTransaction()) {
       return 0.25;
     }
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return 0.5;
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         if ($this->isSelfSubscription()) {
           // Make this weaker than TYPE_COMMENT.
           return 0.25;
         }
         break;
     }
 
     return 1.0;
   }
 
   public function isCommentTransaction() {
     if ($this->hasComment()) {
       return true;
     }
 
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return true;
     }
 
     return false;
   }
 
   public function isInlineCommentTransaction() {
     return false;
   }
 
   public function getActionName() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_COMMENT:
         return pht('Commented On');
       case PhabricatorTransactions::TYPE_VIEW_POLICY:
       case PhabricatorTransactions::TYPE_EDIT_POLICY:
       case PhabricatorTransactions::TYPE_JOIN_POLICY:
         return pht('Changed Policy');
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
         return pht('Changed Subscribers');
       case PhabricatorTransactions::TYPE_BUILDABLE:
         switch ($this->getNewValue()) {
           case HarbormasterBuildable::STATUS_PASSED:
             return pht('Build Passed');
           case HarbormasterBuildable::STATUS_FAILED:
             return pht('Build Failed');
           default:
             return pht('Build Status');
         }
       default:
         return pht('Updated');
     }
   }
 
   public function getMailTags() {
     return array();
   }
 
   public function hasChangeDetails() {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionHasChangeDetails($this);
         }
         break;
     }
     return false;
   }
 
   public function renderChangeDetails(PhabricatorUser $viewer) {
     switch ($this->getTransactionType()) {
       case PhabricatorTransactions::TYPE_CUSTOMFIELD:
         $field = $this->getTransactionCustomField();
         if ($field) {
           return $field->getApplicationTransactionChangeDetails($this, $viewer);
         }
         break;
     }
 
     return $this->renderTextCorpusChangeDetails(
       $viewer,
       $this->getOldValue(),
       $this->getNewValue());
   }
 
   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, __CLASS__);
     $this->transactionGroup = $group;
     return $this;
   }
 
   public function getTransactionGroup() {
     return $this->transactionGroup;
   }
 
   /**
    * Should this transaction be visually grouped with an existing transaction
    * group?
    *
    * @param list<PhabricatorApplicationTransaction> List of transactions.
    * @return bool True to display in a group with the other transactions.
    */
   public function shouldDisplayGroupWith(array $group) {
     $this_source = null;
     if ($this->getContentSource()) {
       $this_source = $this->getContentSource()->getSource();
     }
 
     foreach ($group as $xaction) {
       // Don't group transactions by different authors.
       if ($xaction->getAuthorPHID() != $this->getAuthorPHID()) {
         return false;
       }
 
       // Don't group transactions for different objects.
       if ($xaction->getObjectPHID() != $this->getObjectPHID()) {
         return false;
       }
 
       // Don't group anything into a group which already has a comment.
       if ($xaction->isCommentTransaction()) {
         return false;
       }
 
       // Don't group transactions from different content sources.
       $other_source = null;
       if ($xaction->getContentSource()) {
         $other_source = $xaction->getContentSource()->getSource();
       }
 
       if ($other_source != $this_source) {
         return false;
       }
 
       // Don't group transactions which happened more than 2 minutes apart.
       $apart = abs($xaction->getDateCreated() - $this->getDateCreated());
       if ($apart > (60 * 2)) {
         return false;
       }
     }
 
     return true;
   }
 
   public function renderExtraInformationLink() {
     $herald_xscript_id = $this->getMetadataValue('herald:transcriptID');
 
     if ($herald_xscript_id) {
       return phutil_tag(
         'a',
         array(
           'href' => '/herald/transcript/'.$herald_xscript_id.'/',
         ),
         pht('View Herald Transcript'));
     }
 
     return null;
   }
 
   public function renderAsTextForDoorkeeper(
     DoorkeeperFeedStoryPublisher $publisher,
     PhabricatorFeedStory $story,
     array $xactions) {
 
     $text = array();
     $body = array();
 
     foreach ($xactions as $xaction) {
       $xaction_body = $xaction->getBodyForMail();
       if ($xaction_body !== null) {
         $body[] = $xaction_body;
       }
 
       if ($xaction->shouldHideForMail($xactions)) {
         continue;
       }
 
       $old_target = $xaction->getRenderingTarget();
       $new_target = self::TARGET_TEXT;
       $xaction->setRenderingTarget($new_target);
 
       if ($publisher->getRenderWithImpliedContext()) {
         $text[] = $xaction->getTitle();
       } else {
         $text[] = $xaction->getTitleForFeed();
       }
 
       $xaction->setRenderingTarget($old_target);
     }
 
     $text = implode("\n", $text);
     $body = implode("\n\n", $body);
 
     return rtrim($text."\n\n".$body);
   }
 
   /**
    * Test if this transaction is just a user subscribing or unsubscribing
    * themselves.
    */
   private function isSelfSubscription() {
     $type = $this->getTransactionType();
     if ($type != PhabricatorTransactions::TYPE_SUBSCRIBERS) {
       return false;
     }
 
     $old = $this->getOldValue();
     $new = $this->getNewValue();
 
     $add = array_diff($old, $new);
     $rem = array_diff($new, $old);
 
     if ((count($add) + count($rem)) != 1) {
       // More than one user affected.
       return false;
     }
 
     $affected_phid = head(array_merge($add, $rem));
     if ($affected_phid != $this->getAuthorPHID()) {
       // Affected user is someone else.
       return false;
     }
 
     return true;
   }
 
+  private function getInterestingMoves(array $moves) {
+    // Remove moves which only shift the position of a task within a column.
+    foreach ($moves as $key => $move) {
+      $from_phids = array_fuse($move['fromColumnPHIDs']);
+      if (isset($from_phids[$move['columnPHID']])) {
+        unset($moves[$key]);
+      }
+    }
+
+    return $moves;
+  }
+
 
 /* -(  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) {
     return pht(
       'Transactions are visible to users that can see the object which was '.
       'acted upon. Some transactions - in particular, comments - are '.
       'editable by the transaction author.');
   }
 
 
 /* -(  PhabricatorDestructibleInterface  )----------------------------------- */
 
 
   public function destroyObjectPermanently(
     PhabricatorDestructionEngine $engine) {
 
     $this->openTransaction();
       $comment_template = null;
       try {
         $comment_template = $this->getApplicationTransactionCommentObject();
       } catch (Exception $ex) {
         // Continue; no comments for these transactions.
       }
 
       if ($comment_template) {
         $comments = $comment_template->loadAllWhere(
           'transactionPHID = %s',
           $this->getPHID());
         foreach ($comments as $comment) {
           $engine->destroyObject($comment);
         }
       }
 
       $this->delete();
     $this->saveTransaction();
   }
 
 
 }