Index: src/applications/differential/controller/DifferentialRevisionViewController.php
===================================================================
--- src/applications/differential/controller/DifferentialRevisionViewController.php
+++ src/applications/differential/controller/DifferentialRevisionViewController.php
@@ -91,9 +91,6 @@
     $aux_fields = $this->loadAuxiliaryFields($revision);
 
     $comments = $revision->loadComments();
-    $comments = array_merge(
-      $this->getImplicitComments($revision, reset($diffs)),
-      $comments);
 
     $all_changesets = $changesets;
     $inlines = $this->loadInlineComments(
@@ -111,22 +108,8 @@
       mpull($comments, 'getAuthorPHID'));
 
     foreach ($comments as $comment) {
-      $metadata = $comment->getMetadata();
-      $added_reviewers = idx(
-        $metadata,
-        DifferentialComment::METADATA_ADDED_REVIEWERS);
-      if ($added_reviewers) {
-        foreach ($added_reviewers as $phid) {
-          $object_phids[] = $phid;
-        }
-      }
-      $added_ccs = idx(
-        $metadata,
-        DifferentialComment::METADATA_ADDED_CCS);
-      if ($added_ccs) {
-        foreach ($added_ccs as $phid) {
-          $object_phids[] = $phid;
-        }
+      foreach ($comment->getRequiredHandlePHIDs() as $phid) {
+        $object_phids[] = $phid;
       }
     }
 
@@ -479,38 +462,6 @@
       ));
   }
 
-  private function getImplicitComments(
-    DifferentialRevision $revision,
-    DifferentialDiff $diff) {
-
-    $author_phid = nonempty(
-      $diff->getAuthorPHID(),
-      $revision->getAuthorPHID());
-
-    $template = new DifferentialComment();
-    $template->setAuthorPHID($author_phid);
-    $template->setRevisionID($revision->getID());
-    $template->setDateCreated($revision->getDateCreated());
-
-    $comments = array();
-
-    if (strlen($revision->getSummary())) {
-      $summary_comment = clone $template;
-      $summary_comment->setContent($revision->getSummary());
-      $summary_comment->setAction(DifferentialAction::ACTION_SUMMARIZE);
-      $comments[] = $summary_comment;
-    }
-
-    if (strlen($revision->getTestPlan())) {
-      $testplan_comment = clone $template;
-      $testplan_comment->setContent($revision->getTestPlan());
-      $testplan_comment->setAction(DifferentialAction::ACTION_TESTPLAN);
-      $comments[] = $testplan_comment;
-    }
-
-    return $comments;
-  }
-
   private function getRevisionActions(DifferentialRevision $revision) {
     $user = $this->getRequest()->getUser();
     $viewer_phid = $user->getPHID();
Index: src/applications/differential/editor/DifferentialCommentEditor.php
===================================================================
--- src/applications/differential/editor/DifferentialCommentEditor.php
+++ src/applications/differential/editor/DifferentialCommentEditor.php
@@ -566,7 +566,7 @@
 
     $comment = id(new DifferentialComment())
       ->setAuthorPHID($actor_phid)
-      ->setRevisionID($revision->getID())
+      ->setRevision($revision)
       ->setAction($action)
       ->setContent((string)$this->message)
       ->setMetadata($metadata);
Index: src/applications/differential/editor/DifferentialRevisionEditor.php
===================================================================
--- src/applications/differential/editor/DifferentialRevisionEditor.php
+++ src/applications/differential/editor/DifferentialRevisionEditor.php
@@ -783,10 +783,9 @@
 
 
   private function createComment() {
-    $revision_id = $this->revision->getID();
     $comment = id(new DifferentialComment())
       ->setAuthorPHID($this->getActorPHID())
-      ->setRevisionID($revision_id)
+      ->setRevision($this->revision)
       ->setContent($this->getComments())
       ->setAction(DifferentialAction::ACTION_UPDATE)
       ->setMetadata(
Index: src/applications/differential/storage/DifferentialComment.php
===================================================================
--- src/applications/differential/storage/DifferentialComment.php
+++ src/applications/differential/storage/DifferentialComment.php
@@ -20,11 +20,39 @@
 
   private $arbitraryDiffForFacebook;
 
+  public function setRevision(DifferentialRevision $revision) {
+    return $this->setRevisionID($revision->getID());
+  }
+
   public function giveFacebookSomeArbitraryDiff(DifferentialDiff $diff) {
     $this->arbitraryDiffForFacebook = $diff;
     return $this;
   }
 
+  public function getRequiredHandlePHIDs() {
+    $phids = array();
+
+    $metadata = $this->getMetadata();
+    $added_reviewers = idx(
+      $metadata,
+      self::METADATA_ADDED_REVIEWERS);
+    if ($added_reviewers) {
+      foreach ($added_reviewers as $phid) {
+        $phids[] = $phid;
+      }
+    }
+    $added_ccs = idx(
+      $metadata,
+      self::METADATA_ADDED_CCS);
+    if ($added_ccs) {
+      foreach ($added_ccs as $phid) {
+        $phids[] = $phid;
+      }
+    }
+
+    return $phids;
+  }
+
   public function getConfiguration() {
     return array(
       self::CONFIG_SERIALIZATION => array(
@@ -42,16 +70,8 @@
     return PhabricatorContentSource::newFromSerialized($this->contentSource);
   }
 
-
   public function getMarkupFieldKey($field) {
-    if ($this->getID()) {
-      return 'DC:'.$this->getID();
-    }
-
-    // The summary and test plan render as comments, but do not have IDs.
-    // They are also mutable. Build keys using content hashes.
-    $hash = PhabricatorHash::digest($this->getMarkupText($field));
-    return 'DC:'.$hash;
+    return 'DC:'.$this->getID();
   }
 
   public function newMarkupEngine($field) {
@@ -70,18 +90,7 @@
   }
 
   public function shouldUseMarkupCache($field) {
-    if ($this->getID()) {
-      return true;
-    }
-
-    $action = $this->getAction();
-    switch ($action) {
-      case DifferentialAction::ACTION_SUMMARIZE:
-      case DifferentialAction::ACTION_TESTPLAN:
-        return true;
-    }
-
-    return false;
+    return (bool)$this->getID();
   }
 
 }
Index: src/applications/differential/view/DifferentialRevisionDetailView.php
===================================================================
--- src/applications/differential/view/DifferentialRevisionDetailView.php
+++ src/applications/differential/view/DifferentialRevisionDetailView.php
@@ -112,6 +112,28 @@
     $properties->setHasKeyboardShortcuts(true);
     $properties->setActionList($actions);
 
+    $properties->invokeWillRenderEvent();
+
+    if (strlen($revision->getSummary())) {
+      $properties->addSectionHeader(pht('Summary'));
+      $properties->addTextContent(
+        PhabricatorMarkupEngine::renderOneObject(
+          id(new PhabricatorMarkupOneOff())->setContent(
+            $revision->getSummary()),
+          'default',
+          $user));
+    }
+
+    if (strlen($revision->getTestPlan())) {
+      $properties->addSectionHeader(pht('Test Plan'));
+      $properties->addTextContent(
+        PhabricatorMarkupEngine::renderOneObject(
+          id(new PhabricatorMarkupOneOff())->setContent(
+            $revision->getTestPlan()),
+          'default',
+          $user));
+    }
+
     $object_box = id(new PHUIObjectBoxView())
       ->setHeader($header)
       ->addPropertyList($properties);