commit 30af8e9c120061b7d7883fa401febae0e3b220b7
Author: epriestley <git@epriestley.com>
Date:   Fri Jan 13 15:06:25 2017 -0800

    WIP

diff --git a/src/applications/differential/customfield/DifferentialMagicFlagField.php b/src/applications/differential/customfield/DifferentialMagicFlagField.php
new file mode 100644
index 000000000..618b18cc5
--- /dev/null
+++ b/src/applications/differential/customfield/DifferentialMagicFlagField.php
@@ -0,0 +1,100 @@
+<?php
+
+final class DifferentialMagicFlagField
+  extends DifferentialStoredCustomField {
+
+  public function getFieldKey() {
+    return 'magic.flag';
+  }
+
+  public function getFieldName() {
+    return pht('Magic Flag');
+  }
+
+  public function getFieldDescription() {
+    return pht('A magic flag.');
+  }
+
+  public function shouldAppearInPropertyView() {
+    return true;
+  }
+
+  public function renderPropertyViewLabel() {
+    return $this->getFieldName();
+  }
+
+  public function renderPropertyViewValue(array $handles) {
+    if (!strlen($this->getValue())) {
+      return null;
+    }
+
+    return $this->getValue();
+  }
+
+  public function shouldAppearInApplicationTransactions() {
+    return true;
+  }
+
+  public function getOldValueForApplicationTransactions() {
+    return $this->getValue();
+  }
+
+  public function getNewValueForApplicationTransactions() {
+    return $this->getValue();
+  }
+
+  public function shouldAppearInEditView() {
+    return true;
+  }
+
+  public function renderEditControl(array $handles) {
+    // This is not editable from the web UI.
+    return null;
+  }
+
+  public function readValueFromRequest(AphrontRequest $request) {
+    return null;
+  }
+
+  public function getApplicationTransactionTitle(
+    PhabricatorApplicationTransaction $xaction) {
+    $author_phid = $xaction->getAuthorPHID();
+    $old = $xaction->getOldValue();
+    $new = $xaction->getNewValue();
+
+    return pht(
+      '%s edited the magic flag: "%s" became "%s".',
+      $xaction->renderHandleLink($author_phid),
+      $old,
+      $new);
+  }
+
+  public function getApplicationTransactionTitleForFeed(
+    PhabricatorApplicationTransaction $xaction) {
+
+    $object_phid = $xaction->getObjectPHID();
+    $author_phid = $xaction->getAuthorPHID();
+    $old = $xaction->getOldValue();
+    $new = $xaction->getNewValue();
+
+    return pht(
+      '%s edited the magic flag for %s: "%s" became "%s".',
+      $xaction->renderHandleLink($author_phid),
+      $xaction->renderHandleLink($object_phid),
+      $old,
+      $new);
+  }
+
+  public function shouldAppearInConduitDictionary() {
+    return true;
+  }
+
+  public function shouldAppearInConduitTransactions() {
+    return true;
+  }
+
+  protected function newConduitEditParameterType() {
+    return new ConduitStringParameterType();
+  }
+
+}
diff --git a/src/applications/differential/field/MagicFlagCommitMessageField.php b/src/applications/differential/field/MagicFlagCommitMessageField.php
new file mode 100644
index 000000000..93de09449
--- /dev/null
+++ b/src/applications/differential/field/MagicFlagCommitMessageField.php
@@ -0,0 +1,36 @@
+<?php
+
+final class MagicFlagCommitMessageField
+  extends DifferentialCommitMessageCustomField {
+
+  const FIELDKEY = 'magic.flag';
+
+  public function getFieldName() {
+    return pht('MagicFlag');
+  }
+
+  public function getCustomFieldKey() {
+    return 'magic.flag';
+  }
+
+  public function getFieldOrder() {
+    return 1000000;
+  }
+
+  public function isFieldEditable() {
+    return false;
+  }
+
+  public function isTemplateField() {
+    return false;
+  }
+
+  public function renderFieldValue($value) {
+    if (strlen($value)) {
+      return "\nMagicFlag={$value}";
+    } else {
+      return null;
+    }
+  }
+
+}

public function readFieldValueFromObject(DifferentialRevision $revision) {
    $cf = PhabricatorCustomField::getObjectFields(
               $revision,
               PhabricatorCustomField::ROLE_STORAGE);
    $cf->readFieldsFromObject($revision);

    id(new PhabricatorCustomFieldStorageQuery())
      ->addField(idx($cf->getFields(), $this::FIELDKEY))
      ->execute();

    return idx($cf->getFields(), $this::FIELDKEY)
      ->getConduitDictionaryValue();
  }