diff --git a/src/applications/differential/customfield/DifferentialSummaryField.php b/src/applications/differential/customfield/DifferentialSummaryField.php
--- a/src/applications/differential/customfield/DifferentialSummaryField.php
+++ b/src/applications/differential/customfield/DifferentialSummaryField.php
@@ -7,10 +7,6 @@
     return 'differential:summary';
   }
 
-  public function getFieldKeyForConduit() {
-    return 'summary';
-  }
-
   public function getFieldName() {
     return pht('Summary');
   }
@@ -27,69 +23,6 @@
     return $revision->getSummary();
   }
 
-  protected function writeValueToRevision(
-    DifferentialRevision $revision,
-    $value) {
-    $revision->setSummary($value);
-  }
-
-  public function readValueFromRequest(AphrontRequest $request) {
-    $this->setValue($request->getStr($this->getFieldKey()));
-  }
-
-  public function renderEditControl(array $handles) {
-    return id(new PhabricatorRemarkupControl())
-      ->setUser($this->getViewer())
-      ->setName($this->getFieldKey())
-      ->setValue($this->getValue())
-      ->setError($this->getFieldError())
-      ->setLabel($this->getFieldName());
-  }
-
-  public function getApplicationTransactionTitle(
-    PhabricatorApplicationTransaction $xaction) {
-    $author_phid = $xaction->getAuthorPHID();
-    $old = $xaction->getOldValue();
-    $new = $xaction->getNewValue();
-
-    return pht(
-      '%s updated the summary for this revision.',
-      $xaction->renderHandleLink($author_phid));
-  }
-
-  public function getApplicationTransactionTitleForFeed(
-    PhabricatorApplicationTransaction $xaction) {
-
-    $object_phid = $xaction->getObjectPHID();
-    $author_phid = $xaction->getAuthorPHID();
-    $old = $xaction->getOldValue();
-    $new = $xaction->getNewValue();
-
-    return pht(
-      '%s updated the summary for %s.',
-      $xaction->renderHandleLink($author_phid),
-      $xaction->renderHandleLink($object_phid));
-  }
-
-  public function getApplicationTransactionHasChangeDetails(
-    PhabricatorApplicationTransaction $xaction) {
-    return true;
-  }
-
-  public function getApplicationTransactionChangeDetails(
-    PhabricatorApplicationTransaction $xaction,
-    PhabricatorUser $viewer) {
-    return $xaction->renderTextCorpusChangeDetails(
-      $viewer,
-      $xaction->getOldValue(),
-      $xaction->getNewValue());
-  }
-
-  public function shouldHideInApplicationTransactions(
-    PhabricatorApplicationTransaction $xaction) {
-    return ($xaction->getOldValue() === null);
-  }
-
   public function shouldAppearInGlobalSearch() {
     return true;
   }
@@ -125,23 +58,6 @@
     return new PHUIRemarkupView($this->getViewer(), $this->getValue());
   }
 
-  public function getApplicationTransactionRemarkupBlocks(
-    PhabricatorApplicationTransaction $xaction) {
-    return array($xaction->getNewValue());
-  }
-
-  public function shouldAppearInCommitMessage() {
-    return true;
-  }
-
-  public function shouldAppearInCommitMessageTemplate() {
-    return true;
-  }
-
-  public function shouldOverwriteWhenCommitMessageIsEdited() {
-    return true;
-  }
-
   public function shouldAppearInTransactionMail() {
     return true;
   }