diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -1847,9 +1847,12 @@
     'PhabricatorApplicationDatasource' => 'applications/meta/typeahead/PhabricatorApplicationDatasource.php',
     'PhabricatorApplicationDetailViewController' => 'applications/meta/controller/PhabricatorApplicationDetailViewController.php',
     'PhabricatorApplicationEditController' => 'applications/meta/controller/PhabricatorApplicationEditController.php',
+    'PhabricatorApplicationEditEngine' => 'applications/meta/editor/PhabricatorApplicationEditEngine.php',
     'PhabricatorApplicationEditHTTPParameterHelpView' => 'applications/transactions/view/PhabricatorApplicationEditHTTPParameterHelpView.php',
+    'PhabricatorApplicationEditor' => 'applications/meta/editor/PhabricatorApplicationEditor.php',
     'PhabricatorApplicationEmailCommandsController' => 'applications/meta/controller/PhabricatorApplicationEmailCommandsController.php',
     'PhabricatorApplicationPanelController' => 'applications/meta/controller/PhabricatorApplicationPanelController.php',
+    'PhabricatorApplicationPolicyChangeTransaction' => 'applications/meta/xactions/PhabricatorApplicationPolicyChangeTransaction.php',
     'PhabricatorApplicationProfileMenuItem' => 'applications/search/menuitem/PhabricatorApplicationProfileMenuItem.php',
     'PhabricatorApplicationQuery' => 'applications/meta/query/PhabricatorApplicationQuery.php',
     'PhabricatorApplicationSchemaSpec' => 'applications/meta/storage/PhabricatorApplicationSchemaSpec.php',
@@ -6848,9 +6851,12 @@
     'PhabricatorApplicationDatasource' => 'PhabricatorTypeaheadDatasource',
     'PhabricatorApplicationDetailViewController' => 'PhabricatorApplicationsController',
     'PhabricatorApplicationEditController' => 'PhabricatorApplicationsController',
+    'PhabricatorApplicationEditEngine' => 'PhabricatorEditEngine',
     'PhabricatorApplicationEditHTTPParameterHelpView' => 'AphrontView',
+    'PhabricatorApplicationEditor' => 'PhabricatorApplicationTransactionEditor',
     'PhabricatorApplicationEmailCommandsController' => 'PhabricatorApplicationsController',
     'PhabricatorApplicationPanelController' => 'PhabricatorApplicationsController',
+    'PhabricatorApplicationPolicyChangeTransaction' => 'PhabricatorApplicationTransactionType',
     'PhabricatorApplicationProfileMenuItem' => 'PhabricatorProfileMenuItem',
     'PhabricatorApplicationQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
     'PhabricatorApplicationSchemaSpec' => 'PhabricatorConfigSchemaSpec',
diff --git a/src/applications/meta/controller/PhabricatorApplicationDetailViewController.php b/src/applications/meta/controller/PhabricatorApplicationDetailViewController.php
--- a/src/applications/meta/controller/PhabricatorApplicationDetailViewController.php
+++ b/src/applications/meta/controller/PhabricatorApplicationDetailViewController.php
@@ -38,6 +38,11 @@
       $header->setStatus('fa-ban', 'dark', pht('Uninstalled'));
     }
 
+    $timeline = $this->buildTransactionTimeline(
+      $selected,
+      new PhabricatorApplicationApplicationTransactionQuery());
+    $timeline->setShouldTerminate(true);
+
     $curtain = $this->buildCurtain($selected);
     $details = $this->buildPropertySectionView($selected);
     $policies = $this->buildPolicyView($selected);
@@ -61,6 +66,7 @@
       ->setMainColumn(array(
           $policies,
           $panels,
+          $timeline,
         ))
       ->addPropertySection(pht('Details'), $details);
 
diff --git a/src/applications/meta/controller/PhabricatorApplicationEditController.php b/src/applications/meta/controller/PhabricatorApplicationEditController.php
--- a/src/applications/meta/controller/PhabricatorApplicationEditController.php
+++ b/src/applications/meta/controller/PhabricatorApplicationEditController.php
@@ -30,11 +30,15 @@
       ->execute();
 
     if ($request->isFormPost()) {
+      $xactions = array();
+
       $result = array();
+      $template = $application->getApplicationTransactionTemplate();
       foreach ($application->getCapabilities() as $capability) {
         $old = $application->getPolicy($capability);
         $new = $request->getStr('policy:'.$capability);
 
+        // XXX what if new is null?
         if ($old == $new) {
           // No change to the setting.
           continue;
@@ -63,41 +67,23 @@
         }
 
         $result[$capability] = $new;
+
+        $xactions[] = id(clone $template)
+          ->setTransactionType(
+              PhabricatorApplicationPolicyChangeTransaction::TRANSACTIONTYPE)
+          ->setMetadataValue('capability.name', $capability)
+          ->setNewValue($new);
       }
 
       if ($result) {
-        $key = 'phabricator.application-settings';
-        $config_entry = PhabricatorConfigEntry::loadConfigEntry($key);
-        $value = $config_entry->getValue();
-
-        $phid = $application->getPHID();
-        if (empty($value[$phid])) {
-          $value[$application->getPHID()] = array();
-        }
-        if (empty($value[$phid]['policy'])) {
-          $value[$phid]['policy'] = array();
-        }
-
-        $value[$phid]['policy'] = $result + $value[$phid]['policy'];
-
-        // Don't allow users to make policy edits which would lock them out of
-        // applications, since they would be unable to undo those actions.
-        PhabricatorEnv::overrideConfig($key, $value);
-        PhabricatorPolicyFilter::mustRetainCapability(
-          $user,
-          $application,
-          PhabricatorPolicyCapability::CAN_VIEW);
-
-        PhabricatorPolicyFilter::mustRetainCapability(
-          $user,
-          $application,
-          PhabricatorPolicyCapability::CAN_EDIT);
-
-        PhabricatorConfigEditor::storeNewValue(
-          $user,
-          $config_entry,
-          $value,
-          PhabricatorContentSource::newFromRequest($request));
+        // $this->simulateNewConfig($application, $user, $result);
+
+        id(new PhabricatorApplicationEditor())
+          ->setActor($user)
+          ->setContentSourceFromRequest($request)
+          ->setContinueOnNoEffect(true)
+          ->setContinueOnMissingFields(true)
+          ->applyTransactions($application, $xactions);
       }
 
       return id(new AphrontRedirectResponse())->setURI($view_uri);
@@ -194,4 +180,36 @@
       ->appendChild($view);
   }
 
+  private function simulateNewConfig(
+    PhabricatorApplication $application,
+    PhabricatorUser $user,
+    array $new_config) {
+    $key = 'phabricator.application-settings';
+    $config_entry = PhabricatorConfigEntry::loadConfigEntry($key);
+    $value = $config_entry->getValue();
+
+    $phid = $application->getPHID();
+    if (empty($value[$phid])) {
+      $value[$application->getPHID()] = array();
+    }
+    if (empty($value[$phid]['policy'])) {
+      $value[$phid]['policy'] = array();
+    }
+
+    $value[$phid]['policy'] = $new_config + $value[$phid]['policy'];
+
+    // Don't allow users to make policy edits which would lock them out of
+    // applications, since they would be unable to undo those actions.
+    PhabricatorEnv::overrideConfig($key, $value);
+    PhabricatorPolicyFilter::mustRetainCapability(
+      $user,
+      $application,
+      PhabricatorPolicyCapability::CAN_VIEW);
+
+    PhabricatorPolicyFilter::mustRetainCapability(
+      $user,
+      $application,
+      PhabricatorPolicyCapability::CAN_EDIT);
+  }
+
 }
diff --git a/src/applications/meta/editor/PhabricatorApplicationEditEngine.php b/src/applications/meta/editor/PhabricatorApplicationEditEngine.php
new file mode 100644
--- /dev/null
+++ b/src/applications/meta/editor/PhabricatorApplicationEditEngine.php
@@ -0,0 +1,64 @@
+<?php
+
+final class PhabricatorApplicationEditEngine
+  extends PhabricatorEditEngine {
+
+  const ENGINECONST = 'application.application';
+
+  public function getEngineApplicationClass() {
+    return 'PhabricatorApplicationsApplication';
+  }
+
+  public function getEngineName() {
+    return pht('Applications');
+  }
+
+  public function getSummaryHeader() {
+    return pht('Configure Application Forms');
+  }
+
+  public function getSummaryText() {
+    return pht('Configure creation and editing forms in Applications.');
+  }
+
+  public function isEngineConfigurable() {
+    return false;
+  }
+
+  protected function newEditableObject() {
+    throw new PhutilMethodNotImplementedException();
+  }
+
+  protected function newObjectQuery() {
+    return new PhabricatorApplicationQuery();
+  }
+
+  protected function getObjectCreateTitleText($object) {
+    return pht('Create New Application');
+  }
+
+  protected function getObjectEditTitleText($object) {
+    return pht('Edit Application: %s', $object->getName());
+  }
+
+  protected function getObjectEditShortText($object) {
+    return $object->getName();
+  }
+
+  protected function getObjectCreateShortText() {
+    return pht('Create Application');
+  }
+
+  protected function getObjectName() {
+    return pht('Application');
+  }
+
+  protected function getObjectViewURI($object) {
+    return $object->getViewURI();
+  }
+
+  protected function buildCustomEditFields($object) {
+    return array();
+  }
+
+}
diff --git a/src/applications/meta/editor/PhabricatorApplicationEditor.php b/src/applications/meta/editor/PhabricatorApplicationEditor.php
new file mode 100644
--- /dev/null
+++ b/src/applications/meta/editor/PhabricatorApplicationEditor.php
@@ -0,0 +1,42 @@
+<?php
+
+final class PhabricatorApplicationEditor
+  extends PhabricatorApplicationTransactionEditor {
+
+  public function getEditorApplicationClass() {
+    return 'PhabricatorApplicationsApplication';
+  }
+
+  public function getEditorObjectsDescription() {
+    return pht('Application');
+  }
+
+  protected function supportsSearch() {
+    return true;
+  }
+
+  public function getTransactionTypes() {
+    $types = parent::getTransactionTypes();
+    $types[] = PhabricatorTransactions::TYPE_VIEW_POLICY;
+    $types[] = PhabricatorTransactions::TYPE_EDIT_POLICY;
+
+    return $types;
+  }
+
+  protected function shouldSendMail(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+    return false;
+  }
+
+  protected function shouldPublishFeedStory(
+    PhabricatorLiskDAO $object,
+    array $xactions) {
+    return true;
+  }
+
+  protected function getMailTo(PhabricatorLiskDAO $object) {
+    return array();
+  }
+
+}
diff --git a/src/applications/meta/storage/PhabricatorApplicationApplicationTransaction.php b/src/applications/meta/storage/PhabricatorApplicationApplicationTransaction.php
--- a/src/applications/meta/storage/PhabricatorApplicationApplicationTransaction.php
+++ b/src/applications/meta/storage/PhabricatorApplicationApplicationTransaction.php
@@ -11,10 +11,6 @@
     return PhabricatorApplicationApplicationPHIDType::TYPECONST;
   }
 
-  public function getApplicationTransactionCommentObject() {
-  return new PhabricatorApplicationTransactionComment();
-  }
-
   public function getBaseTransactionClass() {
     return 'PhabricatorApplicationTransactionType';
   }
diff --git a/src/applications/meta/xactions/PhabricatorApplicationPolicyChangeTransaction.php b/src/applications/meta/xactions/PhabricatorApplicationPolicyChangeTransaction.php
new file mode 100644
--- /dev/null
+++ b/src/applications/meta/xactions/PhabricatorApplicationPolicyChangeTransaction.php
@@ -0,0 +1,121 @@
+<?php
+
+final class PhabricatorApplicationPolicyChangeTransaction
+  extends PhabricatorApplicationTransactionType {
+
+  const TRANSACTIONTYPE = 'application.policy';
+
+  private $policies;
+
+  public function generateOldValue($object) {
+    $application = $object;
+    $capability = $this->getCapabilityName();
+    return $application->getPolicy($capability);
+  }
+
+  public function applyInternalEffects($object, $value) {
+    $application = $object;
+    $user = $this->getViewer();
+
+    $key = 'phabricator.application-settings';
+    $config_entry = PhabricatorConfigEntry::loadConfigEntry($key);
+    $current_value = $config_entry->getValue();
+
+    $phid = $application->getPHID();
+    if (empty($current_value[$phid])) {
+      $current_value[$application->getPHID()] = array();
+    }
+    if (empty($current_value[$phid]['policy'])) {
+      $current_value[$phid]['policy'] = array();
+    }
+
+    $update = array($this->getCapabilityName() => $value);
+
+    $current_value[$phid]['policy'] = $update + $current_value[$phid]['policy'];
+
+    PhabricatorConfigEditor::storeNewValue(
+      $user,
+      $config_entry,
+      $current_value,
+      PhabricatorContentSource::newForSource('xaction', array(), $force = true));
+  }
+
+  public function getTitle() {
+    $old = $this->renderPolicy($this->getOldValue());
+    $new = $this->renderPolicy($this->getNewValue());
+
+    // austin changed the "View Badges" policy from "Administrators" to "No One"
+    return pht(
+      '%s changed the "%s" policy from %s to %s.',
+      $this->renderAuthor(),
+      $this->renderCapability(),
+      $old,
+      $new);
+  }
+
+  public function getTitleForFeed() {
+    $old = $this->renderPolicy($this->getOldValue());
+    $new = $this->renderPolicy($this->getNewValue());
+
+    // austin changed the "Can Use Application" policy for application
+    // "Badges" from "No One" to "All Users"
+    return pht(
+      '%s changed the "%s" policy for application %s from "%s" to "%s".',
+      $this->renderAuthor(),
+      $this->renderCapability(),
+      $this->renderObject(),
+      $old,
+      $new);
+  }
+
+  public function validateTransactions($object, array $xactions) {
+    $errors = array();
+
+    // TODO should we simulate the policies here instead of before creating the
+    // actions?
+
+    return $errors;
+  }
+
+  // "Administrators", "No One", etc
+  private function renderPolicy($name) {
+    $policies = $this->getAllPolicies();
+
+    $policy_obj = idx($policies, $name);
+    if ($policy_obj !== null) {
+      $policy_label = $policy_obj->getName();
+    } else {
+      $policy_label = $name;
+    }
+
+    return $this->renderValue($policy_label);
+  }
+
+  private function getAllPolicies() {
+    if (!$this->policies) {
+      // cant use PhabricatorPolicyQuery::renderPolicyDescriptions(), because
+      // that only returns:
+      //    array($capability => $currently_configured_policy_description)
+      $viewer = $this->getViewer();
+      $application = $this->getObject();
+      $this->policies = id(new PhabricatorPolicyQuery())
+        ->setViewer($viewer)
+        ->setObject($application)
+        ->execute();
+    }
+
+    return $this->policies;
+  }
+
+  // Should be like "View", "Edit", etc
+  private function renderCapability() {
+    $application = $this->getObject();
+    $capability = $this->getCapabilityName();
+    return $application->getCapabilityLabel($capability);
+  }
+
+  private function getCapabilityName() {
+    return $this->getMetadataValue('capability.name');
+  }
+
+}
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
@@ -322,6 +322,8 @@
 
     $xtype = $this->getModularTransactionType($type);
     if ($xtype) {
+      $xtype = clone $xtype;
+      $xtype->setStorage($xaction);
       return $xtype->generateOldValue($object);
     }
 
@@ -402,6 +404,8 @@
 
     $xtype = $this->getModularTransactionType($type);
     if ($xtype) {
+      $xtype = clone $xtype;
+      $xtype->setStorage($xaction);
       return $xtype->generateNewValue($object, $xaction->getNewValue());
     }
 
@@ -541,6 +545,9 @@
 
     $xtype = $this->getModularTransactionType($type);
     if ($xtype) {
+      $xtype = clone $xtype;
+      $xtype->setStorage($xaction);
+      $xtype->setViewer($xaction->getViewer());
       return $xtype->applyInternalEffects($object, $xaction->getNewValue());
     }
 
@@ -2714,6 +2721,10 @@
       $has_support = true;
     }
 
+    if ($object instanceof PhabricatorApplication) {
+      $has_support = true;
+    }
+
     if ($object instanceof PhabricatorProjectInterface) {
       $project_phids = PhabricatorEdgeQuery::loadDestinationPHIDs(
         $object->getPHID(),
diff --git a/src/applications/transactions/storage/PhabricatorModularTransactionType.php b/src/applications/transactions/storage/PhabricatorModularTransactionType.php
--- a/src/applications/transactions/storage/PhabricatorModularTransactionType.php
+++ b/src/applications/transactions/storage/PhabricatorModularTransactionType.php
@@ -315,4 +315,8 @@
     return $editor->getPHIDList($old, $new);
   }
 
+  public function getMetadataValue($key, $default = null) {
+    return $this->getStorage()->getMetadataValue($key, $default);
+  }
+
 }