diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -13,7 +13,7 @@
     'core.pkg.js' => 'd2de90d9',
     'dark-console.pkg.js' => '187792c2',
     'differential.pkg.css' => 'ffb69e3d',
-    'differential.pkg.js' => 'e31329dc',
+    'differential.pkg.js' => 'c60bec1b',
     'diffusion.pkg.css' => '42c75c37',
     'diffusion.pkg.js' => '78c9885d',
     'maniphest.pkg.css' => '35995d6d',
@@ -473,7 +473,7 @@
     'rsrc/js/core/behavior-copy.js' => 'cf32921f',
     'rsrc/js/core/behavior-detect-timezone.js' => '78bc5d94',
     'rsrc/js/core/behavior-device.js' => 'ac2b1e01',
-    'rsrc/js/core/behavior-drag-and-drop-textarea.js' => '7df68a45',
+    'rsrc/js/core/behavior-drag-and-drop-textarea.js' => '3277c62d',
     'rsrc/js/core/behavior-fancy-datepicker.js' => '36821f8d',
     'rsrc/js/core/behavior-form.js' => '55d7b788',
     'rsrc/js/core/behavior-gesture.js' => 'b58d1a2a',
@@ -589,7 +589,7 @@
     'javelin-behavior-aphlict-listen' => '4e61fa88',
     'javelin-behavior-aphlict-status' => 'c3703a16',
     'javelin-behavior-aphront-basic-tokenizer' => '3b4899b0',
-    'javelin-behavior-aphront-drag-and-drop-textarea' => '7df68a45',
+    'javelin-behavior-aphront-drag-and-drop-textarea' => '3277c62d',
     'javelin-behavior-aphront-form-disable-on-submit' => '55d7b788',
     'javelin-behavior-aphront-more' => '506aa3f4',
     'javelin-behavior-audio-source' => '3dc5ad43',
@@ -1195,6 +1195,13 @@
       'javelin-install',
       'javelin-util',
     ),
+    '3277c62d' => array(
+      'javelin-behavior',
+      'javelin-dom',
+      'javelin-json',
+      'phabricator-drag-and-drop-file-upload',
+      'phabricator-textareautils',
+    ),
     '32db8374' => array(
       'javelin-behavior',
       'javelin-stratcom',
@@ -1614,13 +1621,6 @@
       'javelin-install',
       'javelin-dom',
     ),
-    '7df68a45' => array(
-      'javelin-behavior',
-      'javelin-dom',
-      'javelin-json',
-      'phabricator-drag-and-drop-file-upload',
-      'phabricator-textareautils',
-    ),
     '80bff3af' => array(
       'javelin-install',
       'javelin-typeahead-source',
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
@@ -1908,6 +1908,11 @@
 
     $comment_text = $request->getStr('comment');
 
+    $comment_metadata = $request->getStr('comment_metadata');
+    if (strlen($comment_metadata)) {
+      $comment_metadata = phutil_json_decode($comment_metadata);
+    }
+
     $actions = $request->getStr('editengine.actions');
     if ($actions) {
       $actions = phutil_json_decode($actions);
@@ -1923,10 +1928,9 @@
           $viewer->getPHID(),
           $current_version);
 
-        $is_empty = (!strlen($comment_text) && !$actions);
-
         $draft
           ->setProperty('comment', $comment_text)
+          ->setProperty('metadata', $comment_metadata)
           ->setProperty('actions', $actions)
           ->save();
 
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
@@ -294,18 +294,39 @@
   }
 
   private function renderCommentPanel() {
+    $viewer = $this->getViewer();
+
+    $remarkup_control = id(new PhabricatorRemarkupControl())
+      ->setViewer($viewer)
+      ->setID($this->getCommentID())
+      ->addClass('phui-comment-fullwidth-control')
+      ->addClass('phui-comment-textarea-control')
+      ->setCanPin(true)
+      ->setName('comment');
+
     $draft_comment = '';
+    $draft_metadata = array();
     $draft_key = null;
-    if ($this->getDraft()) {
-      $draft_comment = $this->getDraft()->getDraft();
-      $draft_key = $this->getDraft()->getDraftKey();
+
+    $legacy_draft = $this->getDraft();
+    if ($legacy_draft) {
+      $draft_comment = $legacy_draft->getDraft();
+      $draft_key = $legacy_draft->getDraftKey();
     }
 
     $versioned_draft = $this->getVersionedDraft();
     if ($versioned_draft) {
-      $draft_comment = $versioned_draft->getProperty('comment', '');
+      $draft_comment = $versioned_draft->getProperty(
+        'comment',
+        $draft_comment);
+      $draft_metadata = $versioned_draft->getProperty(
+        'metadata',
+        $draft_metadata);
     }
 
+    $remarkup_control->setValue($draft_comment);
+    $remarkup_control->setRemarkupMetadata($draft_metadata);
+
     if (!$this->getObjectPHID()) {
       throw new PhutilInvalidStateException('setObjectPHID', 'render');
     }
@@ -314,7 +335,7 @@
     $version_value = $this->getCurrentVersion();
 
     $form = id(new AphrontFormView())
-      ->setUser($this->getUser())
+      ->setUser($viewer)
       ->addSigil('transaction-append')
       ->setWorkflow(true)
       ->setFullWidth($this->fullWidth)
@@ -465,15 +486,7 @@
       ->setValue($this->getSubmitButtonName());
 
     $form
-      ->appendChild(
-        id(new PhabricatorRemarkupControl())
-          ->setID($this->getCommentID())
-          ->addClass('phui-comment-fullwidth-control')
-          ->addClass('phui-comment-textarea-control')
-          ->setCanPin(true)
-          ->setName('comment')
-          ->setUser($this->getUser())
-          ->setValue($draft_comment))
+      ->appendChild($remarkup_control)
       ->appendChild(
         id(new AphrontFormSubmitControl())
           ->addClass('phui-comment-fullwidth-control')
diff --git a/webroot/rsrc/js/core/behavior-drag-and-drop-textarea.js b/webroot/rsrc/js/core/behavior-drag-and-drop-textarea.js
--- a/webroot/rsrc/js/core/behavior-drag-and-drop-textarea.js
+++ b/webroot/rsrc/js/core/behavior-drag-and-drop-textarea.js
@@ -16,7 +16,7 @@
 
   function set_metadata(key, value) {
     metadata_value[key] = value;
-    metadata_node.value = JX.JSON.stringify(metadata_value);
+    write_metadata();
   }
 
   function get_metadata(key, default_value) {
@@ -26,6 +26,12 @@
     return default_value;
   }
 
+  function write_metadata() {
+    metadata_node.value = JX.JSON.stringify(metadata_value);
+  }
+
+  write_metadata();
+
   if (JX.PhabricatorDragAndDropFileUpload.isSupported()) {
     var drop = new JX.PhabricatorDragAndDropFileUpload(target)
       .setURI(config.uri)
@@ -41,6 +47,10 @@
 
     drop.listen('didUpload', function(file) {
       JX.TextAreaUtils.insertFileReference(target, file);
+
+      var phids = get_metadata('attachedFilePHIDs', []);
+      phids.push(file.getPHID());
+      set_metadata('attachedFilePHIDs', phids);
     });
 
     drop.start();