diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -420,6 +420,7 @@
     'rsrc/js/application/repository/repository-crossreference.js' => 'e5339c43',
     'rsrc/js/application/search/behavior-reorder-queries.js' => 'e9581f08',
     'rsrc/js/application/slowvote/behavior-slowvote-embed.js' => '887ad43f',
+    'rsrc/js/application/transactions/behavior-comment-actions.js' => 'f2c64202',
     'rsrc/js/application/transactions/behavior-reorder-fields.js' => 'b59e1e96',
     'rsrc/js/application/transactions/behavior-show-older-transactions.js' => 'dbbf48b6',
     'rsrc/js/application/transactions/behavior-transaction-comment-form.js' => 'b23b49e6',
@@ -498,6 +499,8 @@
     'rsrc/js/phuix/PHUIXActionListView.js' => 'b5c256b8',
     'rsrc/js/phuix/PHUIXActionView.js' => '8cf6d262',
     'rsrc/js/phuix/PHUIXDropdownMenu.js' => 'bd4c8dca',
+    'rsrc/js/phuix/PHUIXFormControl.js' => 'f9fba5ee',
+    'rsrc/js/phuix/PHUIXIconView.js' => 'bff6884b',
   ),
   'symbols' => array(
     'almanac-css' => 'dbb9b3af',
@@ -561,6 +564,7 @@
     'javelin-behavior-audit-preview' => 'd835b03a',
     'javelin-behavior-bulk-job-reload' => 'edf8a145',
     'javelin-behavior-choose-control' => '6153c708',
+    'javelin-behavior-comment-actions' => 'f2c64202',
     'javelin-behavior-config-reorder-fields' => 'b6993408',
     'javelin-behavior-conpherence-drag-and-drop-photo' => 'cf86d16a',
     'javelin-behavior-conpherence-menu' => '1d45c74d',
@@ -823,6 +827,8 @@
     'phuix-action-list-view' => 'b5c256b8',
     'phuix-action-view' => '8cf6d262',
     'phuix-dropdown-menu' => 'bd4c8dca',
+    'phuix-form-control-view' => 'f9fba5ee',
+    'phuix-icon-view' => 'bff6884b',
     'policy-css' => '957ea14c',
     'policy-edit-css' => '815c66f7',
     'policy-transaction-detail-css' => '82100a43',
@@ -1767,6 +1773,10 @@
       'javelin-util',
       'javelin-request',
     ),
+    'bff6884b' => array(
+      'javelin-install',
+      'javelin-dom',
+    ),
     'c1700f6f' => array(
       'javelin-install',
       'javelin-util',
@@ -1973,6 +1983,14 @@
       'javelin-workflow',
       'javelin-json',
     ),
+    'f2c64202' => array(
+      'javelin-behavior',
+      'javelin-stratcom',
+      'javelin-workflow',
+      'javelin-dom',
+      'phuix-form-control-view',
+      'phuix-icon-view',
+    ),
     'f36e01af' => array(
       'javelin-behavior',
       'javelin-behavior-device',
@@ -2029,6 +2047,10 @@
       'javelin-util',
       'phabricator-busy',
     ),
+    'f9fba5ee' => array(
+      'javelin-install',
+      'javelin-dom',
+    ),
     'fa0f4fc2' => array(
       'javelin-behavior',
       'javelin-dom',
diff --git a/src/applications/paste/controller/PhabricatorPasteViewController.php b/src/applications/paste/controller/PhabricatorPasteViewController.php
--- a/src/applications/paste/controller/PhabricatorPasteViewController.php
+++ b/src/applications/paste/controller/PhabricatorPasteViewController.php
@@ -34,6 +34,7 @@
       ->setViewer($viewer)
       ->withIDs(array($id))
       ->needContent(true)
+      ->needRawContent(true)
       ->executeOne();
     if (!$paste) {
       return new Aphront404Response();
diff --git a/src/applications/project/editor/PhabricatorProjectsEditEngineExtension.php b/src/applications/project/editor/PhabricatorProjectsEditEngineExtension.php
--- a/src/applications/project/editor/PhabricatorProjectsEditEngineExtension.php
+++ b/src/applications/project/editor/PhabricatorProjectsEditEngineExtension.php
@@ -53,6 +53,7 @@
         pht('Add projects.'),
         pht('Remove projects.'),
         pht('Set associated projects, overwriting current value.'))
+      ->setCommentActionLabel(pht('Add Projects'))
       ->setTransactionType($edge_type)
       ->setMetadataValue('edge:type', $project_edge_type)
       ->setValue($project_phids);
diff --git a/src/applications/subscriptions/editor/PhabricatorSubscriptionsEditEngineExtension.php b/src/applications/subscriptions/editor/PhabricatorSubscriptionsEditEngineExtension.php
--- a/src/applications/subscriptions/editor/PhabricatorSubscriptionsEditEngineExtension.php
+++ b/src/applications/subscriptions/editor/PhabricatorSubscriptionsEditEngineExtension.php
@@ -50,6 +50,7 @@
         pht('Add subscribers.'),
         pht('Remove subscribers.'),
         pht('Set subscribers, overwriting current value.'))
+      ->setCommentActionLabel(pht('Add Subscribers'))
       ->setTransactionType($subscribers_type)
       ->setValue($sub_phids);
 
diff --git a/src/applications/transactions/editengine/PhabricatorEditEngine.php b/src/applications/transactions/editengine/PhabricatorEditEngine.php
--- a/src/applications/transactions/editengine/PhabricatorEditEngine.php
+++ b/src/applications/transactions/editengine/PhabricatorEditEngine.php
@@ -873,6 +873,8 @@
   }
 
   final public function buildEditEngineCommentView($object) {
+    $config = $this->loadEditEngineConfiguration(null);
+
     $viewer = $this->getViewer();
     $object_phid = $object->getPHID();
 
@@ -897,6 +899,19 @@
 
     $view->setCurrentVersion($this->loadDraftVersion($object));
 
+    $fields = $this->buildEditFields($object);
+
+    $all_types = array();
+    foreach ($fields as $field) {
+      // TODO: Load draft stuff.
+      $types = $field->getCommentEditTypes();
+      foreach ($types as $type) {
+        $all_types[] = $type;
+      }
+    }
+
+    $view->setEditTypes($all_types);
+
     return $view;
   }
 
@@ -999,6 +1014,9 @@
       return new Aphront400Response();
     }
 
+    $config = $this->loadEditEngineConfiguration(null);
+    $fields = $this->buildEditFields($object);
+
     $is_preview = $request->isPreviewRequest();
     $view_uri = $this->getObjectViewURI($object);
 
@@ -1025,11 +1043,46 @@
 
     $xactions = array();
 
-    $xactions[] = id(clone $template)
-      ->setTransactionType(PhabricatorTransactions::TYPE_COMMENT)
-      ->attachComment(
-        id(clone $comment_template)
-          ->setContent($comment_text));
+    $actions = $request->getStr('editengine.actions');
+    if ($actions) {
+      $type_map = array();
+      foreach ($fields as $field) {
+        $types = $field->getCommentEditTypes();
+        foreach ($types as $type) {
+          $type_map[$type->getEditType()] = $type;
+        }
+      }
+
+      $actions = phutil_json_decode($actions);
+      foreach ($actions as $action) {
+        $type = idx($action, 'type');
+        if (!$type) {
+          continue;
+        }
+
+        $edit_type = idx($type_map, $type);
+        if (!$edit_type) {
+          continue;
+        }
+
+        $type_xactions = $edit_type->generateTransactions(
+          $template,
+          array(
+            'value' => idx($action, 'value'),
+          ));
+        foreach ($type_xactions as $type_xaction) {
+          $xactions[] = $type_xaction;
+        }
+      }
+    }
+
+    if (strlen($comment_text) || !$xactions) {
+      $xactions[] = id(clone $template)
+        ->setTransactionType(PhabricatorTransactions::TYPE_COMMENT)
+        ->attachComment(
+          id(clone $comment_template)
+            ->setContent($comment_text));
+    }
 
     $editor = $object->getApplicationTransactionEditor()
       ->setActor($viewer)
diff --git a/src/applications/transactions/editfield/PhabricatorEditField.php b/src/applications/transactions/editfield/PhabricatorEditField.php
--- a/src/applications/transactions/editfield/PhabricatorEditField.php
+++ b/src/applications/transactions/editfield/PhabricatorEditField.php
@@ -494,4 +494,8 @@
     return array($edit_type);
   }
 
+  public function getCommentEditTypes() {
+    return array();
+  }
+
 }
diff --git a/src/applications/transactions/editfield/PhabricatorTokenizerEditField.php b/src/applications/transactions/editfield/PhabricatorTokenizerEditField.php
--- a/src/applications/transactions/editfield/PhabricatorTokenizerEditField.php
+++ b/src/applications/transactions/editfield/PhabricatorTokenizerEditField.php
@@ -3,8 +3,19 @@
 abstract class PhabricatorTokenizerEditField
   extends PhabricatorPHIDListEditField {
 
+  private $commentActionLabel;
+
   abstract protected function newDatasource();
 
+  public function setCommentActionLabel($label) {
+    $this->commentActionLabel = $label;
+    return $this;
+  }
+
+  public function getCommentActionLabel() {
+    return $this->commentActionLabel;
+  }
+
   protected function newControl() {
     $control = id(new AphrontFormTokenizerControl())
       ->setDatasource($this->newDatasource());
@@ -21,4 +32,42 @@
     return $request->getArr($key.'.original');
   }
 
+  protected function newEditType() {
+    $type = parent::newEditType();
+
+    if ($this->getUseEdgeTransactions()) {
+      $datasource = $this->newDatasource()
+        ->setViewer($this->getViewer());
+      $type->setDatasource($datasource);
+    }
+
+    return $type;
+  }
+
+  public function getCommentEditTypes() {
+    if (!$this->getUseEdgeTransactions()) {
+      return parent::getCommentEditTypes();
+    }
+
+    $transaction_type = $this->getTransactionType();
+    if ($transaction_type === null) {
+      return array();
+    }
+
+    $label = $this->getCommentActionLabel();
+    if ($label === null) {
+      return array();
+    }
+
+    $type_key = $this->getEditTypeKey();
+    $base = $this->getEditType();
+
+    $add = id(clone $base)
+      ->setEditType($type_key.'.add')
+      ->setEdgeOperation('+')
+      ->setLabel($label);
+
+    return array($add);
+  }
+
 }
diff --git a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
--- a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
+++ b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
@@ -811,7 +811,17 @@
       $this->adjustTransactionValues($object, $xaction);
     }
 
-    $xactions = $this->filterTransactions($object, $xactions);
+    try {
+      $xactions = $this->filterTransactions($object, $xactions);
+    } catch (Exception $ex) {
+      if ($read_locking) {
+        $object->endReadLocking();
+      }
+      if ($transaction_open) {
+        $object->killTransaction();
+      }
+      throw $ex;
+    }
 
     // Now that we've merged, filtered, and combined transactions, check for
     // required capabilities.
diff --git a/src/applications/transactions/edittype/PhabricatorEdgeEditType.php b/src/applications/transactions/edittype/PhabricatorEdgeEditType.php
--- a/src/applications/transactions/edittype/PhabricatorEdgeEditType.php
+++ b/src/applications/transactions/edittype/PhabricatorEdgeEditType.php
@@ -4,6 +4,7 @@
 
   private $edgeOperation;
   private $valueDescription;
+  private $datasource;
 
   public function setEdgeOperation($edge_operation) {
     $this->edgeOperation = $edge_operation;
@@ -14,6 +15,15 @@
     return $this->edgeOperation;
   }
 
+  public function setDatasource($datasource) {
+    $this->datasource = $datasource;
+    return $this;
+  }
+
+  public function getDatasource() {
+    return $this->datasource;
+  }
+
   public function getValueType() {
     return 'list<phid>';
   }
@@ -46,4 +56,33 @@
     return $this->valueDescription;
   }
 
+  public function getPHUIXControlType() {
+    $datasource = $this->getDatasource();
+
+    if (!$datasource) {
+      return null;
+    }
+
+    return 'tokenizer';
+  }
+
+  public function getPHUIXControlSpecification() {
+    $datasource = $this->getDatasource();
+
+    if (!$datasource) {
+      return null;
+    }
+
+    $template = new AphrontTokenizerTemplateView();
+
+    return array(
+      'markup' => $template->render(),
+      'config' => array(
+        'src' => $datasource->getDatasourceURI(),
+        'browseURI' => $datasource->getBrowseURI(),
+        'placeholder' => $datasource->getPlaceholderText(),
+      ),
+    );
+  }
+
 }
diff --git a/src/applications/transactions/edittype/PhabricatorEditType.php b/src/applications/transactions/edittype/PhabricatorEditType.php
--- a/src/applications/transactions/edittype/PhabricatorEditType.php
+++ b/src/applications/transactions/edittype/PhabricatorEditType.php
@@ -4,6 +4,7 @@
 
   private $editType;
   private $transactionType;
+  private $label;
   private $field;
   private $description;
   private $summary;
@@ -30,6 +31,15 @@
     return $this->summary;
   }
 
+  public function setLabel($label) {
+    $this->label = $label;
+    return $this;
+  }
+
+  public function getLabel() {
+    return $this->label;
+  }
+
   public function setField(PhabricatorEditField $field) {
     $this->field = $field;
     return $this;
@@ -86,4 +96,12 @@
     return $xaction;
   }
 
+  public function getPHUIXControlType() {
+    return null;
+  }
+
+  public function getPHUIXControlSpecification() {
+    return null;
+  }
+
 }
diff --git a/src/applications/transactions/view/PhabricatorApplicationTransactionCommentView.php b/src/applications/transactions/view/PhabricatorApplicationTransactionCommentView.php
--- a/src/applications/transactions/view/PhabricatorApplicationTransactionCommentView.php
+++ b/src/applications/transactions/view/PhabricatorApplicationTransactionCommentView.php
@@ -22,6 +22,7 @@
 
   private $currentVersion;
   private $versionedDraft;
+  private $editTypes;
 
   public function setObjectPHID($object_phid) {
     $this->objectPHID = $object_phid;
@@ -100,6 +101,15 @@
     return $this;
   }
 
+  public function setEditTypes($edit_types) {
+    $this->editTypes = $edit_types;
+    return $this;
+  }
+
+  public function getEditTypes() {
+    return $this->editTypes;
+  }
+
   public function render() {
 
     $user = $this->getUser();
@@ -182,7 +192,7 @@
     $version_key = PhabricatorVersionedDraft::KEY_VERSION;
     $version_value = $this->getCurrentVersion();
 
-    return id(new AphrontFormView())
+    $form = id(new AphrontFormView())
       ->setUser($this->getUser())
       ->addSigil('transaction-append')
       ->setWorkflow(true)
@@ -193,7 +203,57 @@
       ->setAction($this->getAction())
       ->setID($this->getFormID())
       ->addHiddenInput('__draft__', $draft_key)
-      ->addHiddenInput($version_key, $version_value)
+      ->addHiddenInput($version_key, $version_value);
+
+    $edit_types = $this->getEditTypes();
+    if ($edit_types) {
+
+      $action_map = array();
+      foreach ($edit_types as $edit_type) {
+        $key = $edit_type->getEditType();
+        $action_map[$key] = array(
+          'key' => $key,
+          'label' => $edit_type->getLabel(),
+          'type' => $edit_type->getPHUIXControlType(),
+          'spec' => $edit_type->getPHUIXControlSpecification(),
+        );
+      }
+
+      $options = array();
+      $options['+'] = pht('Add Action...');
+      foreach ($action_map as $key => $item) {
+        $options[$key] = $item['label'];
+      }
+
+      $action_id = celerity_generate_unique_node_id();
+      $input_id = celerity_generate_unique_node_id();
+
+      $form->appendChild(
+        phutil_tag(
+          'input',
+          array(
+            'type' => 'hidden',
+            'name' => 'editengine.actions',
+            'id' => $input_id,
+          )));
+
+      $form->appendChild(
+        id(new AphrontFormSelectControl())
+          ->setLabel(pht('Actions'))
+          ->setID($action_id)
+          ->setOptions($options));
+
+      Javelin::initBehavior(
+        'comment-actions',
+        array(
+          'actionID' => $action_id,
+          'inputID' => $input_id,
+          'formID' => $this->getFormID(),
+          'actions' => $action_map,
+        ));
+    }
+
+    $form
       ->appendChild(
         id(new PhabricatorRemarkupControl())
           ->setID($this->getCommentID())
@@ -207,6 +267,8 @@
       ->appendChild(
         id(new AphrontFormMarkupControl())
           ->setValue($status));
+
+    return $form;
   }
 
   private function renderPreviewPanel() {
diff --git a/webroot/rsrc/js/application/transactions/behavior-comment-actions.js b/webroot/rsrc/js/application/transactions/behavior-comment-actions.js
new file mode 100644
--- /dev/null
+++ b/webroot/rsrc/js/application/transactions/behavior-comment-actions.js
@@ -0,0 +1,84 @@
+/**
+ * @provides javelin-behavior-comment-actions
+ * @requires javelin-behavior
+ *           javelin-stratcom
+ *           javelin-workflow
+ *           javelin-dom
+ *           phuix-form-control-view
+ *           phuix-icon-view
+ */
+
+JX.behavior('comment-actions', function(config) {
+  var action_map = config.actions;
+
+  var action_node = JX.$(config.actionID);
+  var form_node = JX.$(config.formID);
+  var input_node = JX.$(config.inputID);
+
+  var rows = {};
+
+  JX.DOM.listen(action_node, 'change', null, function() {
+    var options = action_node.options;
+    var option;
+
+    var selected = action_node.value;
+    action_node.value = '+';
+
+    for (var ii = 0; ii < options.length; ii++) {
+      option = options[ii];
+      if (option.value == selected) {
+        add_row(option);
+        break;
+      }
+    }
+  });
+
+  JX.DOM.listen(form_node, 'submit', null, function() {
+    var data = [];
+
+    for (var k in rows) {
+      data.push({
+        type: k,
+        value: rows[k].getValue()
+      });
+    }
+
+    input_node.value = JX.JSON.stringify(data);
+  });
+
+  function add_row(option) {
+    var action = action_map[option.value];
+    if (!action) {
+      return;
+    }
+
+    option.disabled = true;
+
+    var icon = new JX.PHUIXIconView()
+      .setIcon('fa-times-circle');
+    var remove = JX.$N('a', {href: '#'}, icon.getNode());
+
+    var control = new JX.PHUIXFormControl()
+      .setLabel(action.label)
+      .setError(remove)
+      .setControl('tokenizer', action.spec);
+    var node = control.getNode();
+
+    rows[action.key] = control;
+
+    JX.DOM.listen(remove, 'click', null, function(e) {
+      e.kill();
+      JX.DOM.remove(node);
+      delete rows[action.key];
+      option.disabled = false;
+    });
+
+    // TODO: Grotesque.
+    action_node
+      .parentNode
+      .parentNode
+      .parentNode
+      .insertBefore(node, action_node.parentNode.parentNode.nextSibling);
+  }
+
+});
diff --git a/webroot/rsrc/js/phuix/PHUIXFormControl.js b/webroot/rsrc/js/phuix/PHUIXFormControl.js
new file mode 100644
--- /dev/null
+++ b/webroot/rsrc/js/phuix/PHUIXFormControl.js
@@ -0,0 +1,133 @@
+/**
+ * @provides phuix-form-control-view
+ * @requires javelin-install
+ *           javelin-dom
+ */
+
+JX.install('PHUIXFormControl', {
+
+  members: {
+    _node: null,
+    _labelNode: null,
+    _errorNode: null,
+    _inputNode: null,
+    _valueSetCallback: null,
+    _valueGetCallback: null,
+
+    setLabel: function(label) {
+      JX.DOM.setContent(this._getLabelNode(), label);
+      return this;
+    },
+
+    setError: function(error) {
+      JX.DOM.setContent(this._getErrorNode(), error);
+      return this;
+    },
+
+    setControl: function(type, spec) {
+      var node = this._getInputNode();
+
+      var input;
+      switch (type) {
+        case 'tokenizer':
+          input = this._newTokenizer(spec);
+          break;
+        default:
+          // TODO: Default or better error?
+          JX.$E('Bad Input Type');
+          return;
+      }
+
+      JX.DOM.setContent(node, input.node);
+      this._valueGetCallback = input.get;
+      this._valueSetCallback = input.set;
+
+      return this;
+    },
+
+    setValue: function(value) {
+      this._valueSetCallback(value);
+      return this;
+    },
+
+    getValue: function() {
+      return this._valueGetCallback();
+    },
+
+    getNode: function() {
+      if (!this._node) {
+
+        var attrs = {
+          className: 'aphront-form-control grouped'
+        };
+
+        var content = [
+          this._getLabelNode(),
+          this._getErrorNode(),
+          this._getInputNode()
+        ];
+
+        this._node = JX.$N('div', attrs, content);
+      }
+
+      return this._node;
+    },
+
+    _getLabelNode: function() {
+      if (!this._labelNode) {
+        var attrs = {
+          className: 'aphront-form-label'
+        };
+
+        this._labelNode = JX.$N('label', attrs);
+      }
+
+      return this._labelNode;
+    },
+
+    _getErrorNode: function() {
+      if (!this._errorNode) {
+        var attrs = {
+          className: 'aphront-form-error'
+        };
+
+        this._errorNode = JX.$N('span', attrs);
+      }
+
+      return this._errorNode;
+    },
+
+    _getInputNode: function() {
+      if (!this._inputNode) {
+        var attrs = {
+          className: 'aphront-form-input'
+        };
+
+        this._inputNode = JX.$N('div', attrs);
+      }
+
+      return this._inputNode;
+    },
+
+    _newTokenizer: function(spec) {
+      var build = JX.Prefab.newTokenizerFromTemplate(
+        spec.markup,
+        spec.config);
+      build.tokenizer.start();
+
+      return {
+        node: build.node,
+        get: function() {
+          return JX.keys(build.tokenizer.getTokens());
+        },
+        set: function(map) {
+          for (var k in map) {
+            build.tokenizer.addToken(k, map[k]);
+          }
+        }
+      };
+    }
+
+  }
+
+});
diff --git a/webroot/rsrc/js/phuix/PHUIXIconView.js b/webroot/rsrc/js/phuix/PHUIXIconView.js
new file mode 100644
--- /dev/null
+++ b/webroot/rsrc/js/phuix/PHUIXIconView.js
@@ -0,0 +1,47 @@
+/**
+ * @provides phuix-icon-view
+ * @requires javelin-install
+ *           javelin-dom
+ */
+
+JX.install('PHUIXIconView', {
+
+  members: {
+    _node: null,
+    _icon: null,
+    _color: null,
+
+    setIcon: function(icon) {
+      var node = this.getNode();
+      if (this._icon) {
+        JX.DOM.alterClass(node, this._icon, false);
+      }
+      this._icon = icon;
+      JX.DOM.alterClass(node, this._icon, true);
+      return this;
+    },
+
+    setColor: function(color) {
+      var node = this.getNode();
+      if (this._color) {
+        JX.DOM.alterClass(node, this._color, false);
+      }
+      this._color = color;
+      JX.DOM.alterClass(node, this._color, true);
+      return this;
+    },
+
+    getNode: function() {
+      if (!this._node) {
+        var attrs = {
+          className: 'phui-icon-view phui-font-fa'
+        };
+
+        this._node = JX.$N('span', attrs);
+      }
+
+      return this._node;
+    }
+  }
+
+});