diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -10,7 +10,7 @@
     'conpherence.pkg.css' => 'e68cf1fa',
     'conpherence.pkg.js' => '15191c65',
     'core.pkg.css' => '9d1148a4',
-    'core.pkg.js' => '4bde473b',
+    'core.pkg.js' => 'bd89cb1d',
     'differential.pkg.css' => '06dc617c',
     'differential.pkg.js' => 'ef0b989b',
     'diffusion.pkg.css' => 'a2d17c7d',
@@ -425,7 +425,7 @@
     'rsrc/js/application/transactions/behavior-comment-actions.js' => '59e27e74',
     'rsrc/js/application/transactions/behavior-reorder-configs.js' => 'd7a74243',
     'rsrc/js/application/transactions/behavior-reorder-fields.js' => 'b59e1e96',
-    'rsrc/js/application/transactions/behavior-show-older-transactions.js' => '8f29b364',
+    'rsrc/js/application/transactions/behavior-show-older-transactions.js' => '0e1eca96',
     'rsrc/js/application/transactions/behavior-transaction-comment-form.js' => 'b23b49e6',
     'rsrc/js/application/transactions/behavior-transaction-list.js' => '1f6794f6',
     'rsrc/js/application/typeahead/behavior-typeahead-browse.js' => '635de1ec',
@@ -639,7 +639,7 @@
     'javelin-behavior-phabricator-remarkup-assist' => 'acd29eee',
     'javelin-behavior-phabricator-reveal-content' => '60821bc7',
     'javelin-behavior-phabricator-search-typeahead' => 'c3e917d9',
-    'javelin-behavior-phabricator-show-older-transactions' => '8f29b364',
+    'javelin-behavior-phabricator-show-older-transactions' => '0e1eca96',
     'javelin-behavior-phabricator-tooltips' => 'c420b0b9',
     'javelin-behavior-phabricator-transaction-comment-form' => 'b23b49e6',
     'javelin-behavior-phabricator-transaction-list' => '1f6794f6',
@@ -950,6 +950,12 @@
       'javelin-install',
       'phuix-button-view',
     ),
+    '0e1eca96' => array(
+      'javelin-behavior',
+      'javelin-stratcom',
+      'javelin-dom',
+      'phabricator-busy',
+    ),
     '0f764c35' => array(
       'javelin-install',
       'javelin-util',
@@ -1581,12 +1587,6 @@
     '8e1baf68' => array(
       'phui-button-css',
     ),
-    '8f29b364' => array(
-      'javelin-behavior',
-      'javelin-stratcom',
-      'javelin-dom',
-      'phabricator-busy',
-    ),
     '8ff5e24c' => array(
       'javelin-behavior',
       'javelin-stratcom',
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
@@ -647,6 +647,7 @@
     'DifferentialRevisionSummaryTransaction' => 'applications/differential/xaction/DifferentialRevisionSummaryTransaction.php',
     'DifferentialRevisionTestPlanHeraldField' => 'applications/differential/herald/DifferentialRevisionTestPlanHeraldField.php',
     'DifferentialRevisionTestPlanTransaction' => 'applications/differential/xaction/DifferentialRevisionTestPlanTransaction.php',
+    'DifferentialRevisionTimelineEngine' => 'applications/differential/engine/DifferentialRevisionTimelineEngine.php',
     'DifferentialRevisionTitleHeraldField' => 'applications/differential/herald/DifferentialRevisionTitleHeraldField.php',
     'DifferentialRevisionTitleTransaction' => 'applications/differential/xaction/DifferentialRevisionTitleTransaction.php',
     'DifferentialRevisionTransactionType' => 'applications/differential/xaction/DifferentialRevisionTransactionType.php',
@@ -769,6 +770,7 @@
     'DiffusionCommitSearchConduitAPIMethod' => 'applications/diffusion/conduit/DiffusionCommitSearchConduitAPIMethod.php',
     'DiffusionCommitStateTransaction' => 'applications/diffusion/xaction/DiffusionCommitStateTransaction.php',
     'DiffusionCommitTagsController' => 'applications/diffusion/controller/DiffusionCommitTagsController.php',
+    'DiffusionCommitTimelineEngine' => 'applications/diffusion/engine/DiffusionCommitTimelineEngine.php',
     'DiffusionCommitTransactionType' => 'applications/diffusion/xaction/DiffusionCommitTransactionType.php',
     'DiffusionCommitVerifyTransaction' => 'applications/diffusion/xaction/DiffusionCommitVerifyTransaction.php',
     'DiffusionCompareController' => 'applications/diffusion/controller/DiffusionCompareController.php',
@@ -1630,7 +1632,6 @@
     'LegalpadTransaction' => 'applications/legalpad/storage/LegalpadTransaction.php',
     'LegalpadTransactionComment' => 'applications/legalpad/storage/LegalpadTransactionComment.php',
     'LegalpadTransactionQuery' => 'applications/legalpad/query/LegalpadTransactionQuery.php',
-    'LegalpadTransactionView' => 'applications/legalpad/view/LegalpadTransactionView.php',
     'LiskChunkTestCase' => 'infrastructure/storage/lisk/__tests__/LiskChunkTestCase.php',
     'LiskDAO' => 'infrastructure/storage/lisk/LiskDAO.php',
     'LiskDAOTestCase' => 'infrastructure/storage/lisk/__tests__/LiskDAOTestCase.php',
@@ -4433,6 +4434,7 @@
     'PhabricatorStandardCustomFieldUsers' => 'infrastructure/customfield/standard/PhabricatorStandardCustomFieldUsers.php',
     'PhabricatorStandardPageView' => 'view/page/PhabricatorStandardPageView.php',
     'PhabricatorStandardSelectCustomFieldDatasource' => 'infrastructure/customfield/datasource/PhabricatorStandardSelectCustomFieldDatasource.php',
+    'PhabricatorStandardTimelineEngine' => 'applications/transactions/engine/PhabricatorStandardTimelineEngine.php',
     'PhabricatorStaticEditField' => 'applications/transactions/editfield/PhabricatorStaticEditField.php',
     'PhabricatorStatusController' => 'applications/system/controller/PhabricatorStatusController.php',
     'PhabricatorStatusUIExample' => 'applications/uiexample/examples/PhabricatorStatusUIExample.php',
@@ -4532,6 +4534,8 @@
     'PhabricatorTimeFormatSetting' => 'applications/settings/setting/PhabricatorTimeFormatSetting.php',
     'PhabricatorTimeGuard' => 'infrastructure/time/PhabricatorTimeGuard.php',
     'PhabricatorTimeTestCase' => 'infrastructure/time/__tests__/PhabricatorTimeTestCase.php',
+    'PhabricatorTimelineEngine' => 'applications/transactions/engine/PhabricatorTimelineEngine.php',
+    'PhabricatorTimelineInterface' => 'applications/transactions/interface/PhabricatorTimelineInterface.php',
     'PhabricatorTimezoneIgnoreOffsetSetting' => 'applications/settings/setting/PhabricatorTimezoneIgnoreOffsetSetting.php',
     'PhabricatorTimezoneSetting' => 'applications/settings/setting/PhabricatorTimezoneSetting.php',
     'PhabricatorTimezoneSetupCheck' => 'applications/config/check/PhabricatorTimezoneSetupCheck.php',
@@ -4871,6 +4875,7 @@
     'PholioMockSearchEngine' => 'applications/pholio/query/PholioMockSearchEngine.php',
     'PholioMockStatusTransaction' => 'applications/pholio/xaction/PholioMockStatusTransaction.php',
     'PholioMockThumbGridView' => 'applications/pholio/view/PholioMockThumbGridView.php',
+    'PholioMockTimelineEngine' => 'applications/pholio/engine/PholioMockTimelineEngine.php',
     'PholioMockTransactionType' => 'applications/pholio/xaction/PholioMockTransactionType.php',
     'PholioMockViewController' => 'applications/pholio/controller/PholioMockViewController.php',
     'PholioRemarkupRule' => 'applications/pholio/remarkup/PholioRemarkupRule.php',
@@ -5991,6 +5996,7 @@
       'PhabricatorSubscribableInterface',
       'PhabricatorCustomFieldInterface',
       'PhabricatorApplicationTransactionInterface',
+      'PhabricatorTimelineInterface',
       'PhabricatorMentionableInterface',
       'PhabricatorDestructibleInterface',
       'PhabricatorProjectInterface',
@@ -6072,6 +6078,7 @@
     'DifferentialRevisionSummaryTransaction' => 'DifferentialRevisionTransactionType',
     'DifferentialRevisionTestPlanHeraldField' => 'DifferentialRevisionHeraldField',
     'DifferentialRevisionTestPlanTransaction' => 'DifferentialRevisionTransactionType',
+    'DifferentialRevisionTimelineEngine' => 'PhabricatorTimelineEngine',
     'DifferentialRevisionTitleHeraldField' => 'DifferentialRevisionHeraldField',
     'DifferentialRevisionTitleTransaction' => 'DifferentialRevisionTransactionType',
     'DifferentialRevisionTransactionType' => 'PhabricatorModularTransactionType',
@@ -6194,6 +6201,7 @@
     'DiffusionCommitSearchConduitAPIMethod' => 'PhabricatorSearchEngineAPIMethod',
     'DiffusionCommitStateTransaction' => 'DiffusionCommitTransactionType',
     'DiffusionCommitTagsController' => 'DiffusionController',
+    'DiffusionCommitTimelineEngine' => 'PhabricatorTimelineEngine',
     'DiffusionCommitTransactionType' => 'PhabricatorModularTransactionType',
     'DiffusionCommitVerifyTransaction' => 'DiffusionCommitAuditTransaction',
     'DiffusionCompareController' => 'DiffusionController',
@@ -7201,7 +7209,6 @@
     'LegalpadTransaction' => 'PhabricatorModularTransaction',
     'LegalpadTransactionComment' => 'PhabricatorApplicationTransactionComment',
     'LegalpadTransactionQuery' => 'PhabricatorApplicationTransactionQuery',
-    'LegalpadTransactionView' => 'PhabricatorApplicationTransactionView',
     'LiskChunkTestCase' => 'PhabricatorTestCase',
     'LiskDAO' => array(
       'Phobject',
@@ -10079,6 +10086,7 @@
       'HarbormasterBuildkiteBuildableInterface',
       'PhabricatorCustomFieldInterface',
       'PhabricatorApplicationTransactionInterface',
+      'PhabricatorTimelineInterface',
       'PhabricatorFulltextInterface',
       'PhabricatorFerretInterface',
       'PhabricatorConduitResultInterface',
@@ -10469,6 +10477,7 @@
       'AphrontResponseProducerInterface',
     ),
     'PhabricatorStandardSelectCustomFieldDatasource' => 'PhabricatorTypeaheadDatasource',
+    'PhabricatorStandardTimelineEngine' => 'PhabricatorTimelineEngine',
     'PhabricatorStaticEditField' => 'PhabricatorEditField',
     'PhabricatorStatusController' => 'PhabricatorController',
     'PhabricatorStatusUIExample' => 'PhabricatorUIExample',
@@ -10567,6 +10576,7 @@
     'PhabricatorTimeFormatSetting' => 'PhabricatorSelectSetting',
     'PhabricatorTimeGuard' => 'Phobject',
     'PhabricatorTimeTestCase' => 'PhabricatorTestCase',
+    'PhabricatorTimelineEngine' => 'Phobject',
     'PhabricatorTimezoneIgnoreOffsetSetting' => 'PhabricatorInternalSetting',
     'PhabricatorTimezoneSetting' => 'PhabricatorOptionGroupSetting',
     'PhabricatorTimezoneSetupCheck' => 'PhabricatorSetupCheck',
@@ -10967,6 +10977,7 @@
       'PhabricatorTokenReceiverInterface',
       'PhabricatorFlaggableInterface',
       'PhabricatorApplicationTransactionInterface',
+      'PhabricatorTimelineInterface',
       'PhabricatorProjectInterface',
       'PhabricatorDestructibleInterface',
       'PhabricatorSpacesInterface',
@@ -11001,6 +11012,7 @@
     'PholioMockSearchEngine' => 'PhabricatorApplicationSearchEngine',
     'PholioMockStatusTransaction' => 'PholioMockTransactionType',
     'PholioMockThumbGridView' => 'AphrontView',
+    'PholioMockTimelineEngine' => 'PhabricatorTimelineEngine',
     'PholioMockTransactionType' => 'PholioTransactionType',
     'PholioMockViewController' => 'PholioController',
     'PholioRemarkupRule' => 'PhabricatorObjectRemarkupRule',
diff --git a/src/applications/audit/storage/PhabricatorAuditTransaction.php b/src/applications/audit/storage/PhabricatorAuditTransaction.php
--- a/src/applications/audit/storage/PhabricatorAuditTransaction.php
+++ b/src/applications/audit/storage/PhabricatorAuditTransaction.php
@@ -32,10 +32,6 @@
     return new PhabricatorAuditTransactionComment();
   }
 
-  public function getApplicationTransactionViewObject() {
-    return new PhabricatorAuditTransactionView();
-  }
-
   public function getRemarkupBlocks() {
     $blocks = parent::getRemarkupBlocks();
 
diff --git a/src/applications/badges/controller/PhabricatorBadgesCommentController.php b/src/applications/badges/controller/PhabricatorBadgesCommentController.php
--- a/src/applications/badges/controller/PhabricatorBadgesCommentController.php
+++ b/src/applications/badges/controller/PhabricatorBadgesCommentController.php
@@ -51,6 +51,7 @@
 
     if ($request->isAjax() && $is_preview) {
       return id(new PhabricatorApplicationTransactionResponse())
+        ->setObject($badge)
         ->setViewer($viewer)
         ->setTransactions($xactions)
         ->setIsPreview($is_preview);
diff --git a/src/applications/base/controller/PhabricatorController.php b/src/applications/base/controller/PhabricatorController.php
--- a/src/applications/base/controller/PhabricatorController.php
+++ b/src/applications/base/controller/PhabricatorController.php
@@ -482,14 +482,14 @@
     PhabricatorApplicationTransactionInterface $object,
     PhabricatorApplicationTransactionQuery $query,
     PhabricatorMarkupEngine $engine = null,
-    $render_data = array()) {
+    $view_data = array()) {
 
-    $viewer = $this->getRequest()->getUser();
+    $request = $this->getRequest();
+    $viewer = $this->getViewer();
     $xaction = $object->getApplicationTransactionTemplate();
-    $view = $xaction->getApplicationTransactionViewObject();
 
     $pager = id(new AphrontCursorPagerView())
-      ->readFromRequest($this->getRequest())
+      ->readFromRequest($request)
       ->setURI(new PhutilURI(
         '/transactions/showolder/'.$object->getPHID().'/'));
 
@@ -500,6 +500,13 @@
       ->executeWithCursorPager($pager);
     $xactions = array_reverse($xactions);
 
+    $timeline_engine = PhabricatorTimelineEngine::newForObject($object)
+      ->setViewer($viewer)
+      ->setTransactions($xactions)
+      ->setViewData($view_data);
+
+    $view = $timeline_engine->buildTimelineView();
+
     if ($engine) {
       foreach ($xactions as $xaction) {
         if ($xaction->getComment()) {
@@ -513,14 +520,9 @@
     }
 
     $timeline = $view
-      ->setUser($viewer)
-      ->setObjectPHID($object->getPHID())
-      ->setTransactions($xactions)
       ->setPager($pager)
-      ->setRenderData($render_data)
       ->setQuoteTargetID($this->getRequest()->getStr('quoteTargetID'))
       ->setQuoteRef($this->getRequest()->getStr('quoteRef'));
-    $object->willRenderTimeline($timeline, $this->getRequest());
 
     return $timeline;
   }
diff --git a/src/applications/config/controller/PhabricatorConfigHistoryController.php b/src/applications/config/controller/PhabricatorConfigHistoryController.php
--- a/src/applications/config/controller/PhabricatorConfigHistoryController.php
+++ b/src/applications/config/controller/PhabricatorConfigHistoryController.php
@@ -16,18 +16,14 @@
 
     $xaction = $object->getApplicationTransactionTemplate();
 
-    $view = $xaction->getApplicationTransactionViewObject();
-
-    $timeline = $view
-      ->setUser($viewer)
+    $timeline = id(new PhabricatorApplicationTransactionView())
+      ->setViewer($viewer)
       ->setTransactions($xactions)
       ->setRenderAsFeed(true)
       ->setObjectPHID(PhabricatorPHIDConstants::PHID_VOID);
 
     $timeline->setShouldTerminate(true);
 
-    $object->willRenderTimeline($timeline, $this->getRequest());
-
     $title = pht('Settings History');
     $header = $this->buildHeaderView($title);
 
diff --git a/src/applications/differential/engine/DifferentialRevisionTimelineEngine.php b/src/applications/differential/engine/DifferentialRevisionTimelineEngine.php
new file mode 100644
--- /dev/null
+++ b/src/applications/differential/engine/DifferentialRevisionTimelineEngine.php
@@ -0,0 +1,78 @@
+<?php
+
+final class DifferentialRevisionTimelineEngine
+  extends PhabricatorTimelineEngine {
+
+  protected function newTimelineView() {
+    $viewer = $this->getViewer();
+    $xactions = $this->getTransactions();
+    $revision = $this->getObject();
+
+    $view_data = $this->getViewData();
+    if (!$view_data) {
+      $view_data = array();
+    }
+
+    $left = idx($view_data, 'left');
+    $right = idx($view_data, 'right');
+
+    $diffs = id(new DifferentialDiffQuery())
+      ->setViewer($viewer)
+      ->withIDs(array($left, $right))
+      ->execute();
+    $diffs = mpull($diffs, null, 'getID');
+    $left_diff = $diffs[$left];
+    $right_diff = $diffs[$right];
+
+    $old_ids = idx($view_data, 'old');
+    $new_ids = idx($view_data, 'new');
+    $old_ids = array_filter(explode(',', $old_ids));
+    $new_ids = array_filter(explode(',', $new_ids));
+
+    $type_inline = DifferentialTransaction::TYPE_INLINE;
+    $changeset_ids = array_merge($old_ids, $new_ids);
+    $inlines = array();
+    foreach ($xactions as $xaction) {
+      if ($xaction->getTransactionType() == $type_inline) {
+        $inlines[] = $xaction->getComment();
+        $changeset_ids[] = $xaction->getComment()->getChangesetID();
+      }
+    }
+
+    if ($changeset_ids) {
+      $changesets = id(new DifferentialChangesetQuery())
+        ->setViewer($viewer)
+        ->withIDs($changeset_ids)
+        ->execute();
+      $changesets = mpull($changesets, null, 'getID');
+    } else {
+      $changesets = array();
+    }
+
+    foreach ($inlines as $key => $inline) {
+      $inlines[$key] = DifferentialInlineComment::newFromModernComment(
+        $inline);
+    }
+
+    $query = id(new DifferentialInlineCommentQuery())
+      ->needHidden(true)
+      ->setViewer($viewer);
+
+    // NOTE: This is a bit sketchy: this method adjusts the inlines as a
+    // side effect, which means it will ultimately adjust the transaction
+    // comments and affect timeline rendering.
+    $query->adjustInlinesForChangesets(
+      $inlines,
+      array_select_keys($changesets, $old_ids),
+      array_select_keys($changesets, $new_ids),
+      $revision);
+
+    return id(new DifferentialTransactionView())
+      ->setViewData($view_data)
+      ->setChangesets($changesets)
+      ->setRevision($revision)
+      ->setLeftDiff($left_diff)
+      ->setRightDiff($right_diff);
+  }
+
+}
diff --git a/src/applications/differential/storage/DifferentialRevision.php b/src/applications/differential/storage/DifferentialRevision.php
--- a/src/applications/differential/storage/DifferentialRevision.php
+++ b/src/applications/differential/storage/DifferentialRevision.php
@@ -11,6 +11,7 @@
     PhabricatorSubscribableInterface,
     PhabricatorCustomFieldInterface,
     PhabricatorApplicationTransactionInterface,
+    PhabricatorTimelineInterface,
     PhabricatorMentionableInterface,
     PhabricatorDestructibleInterface,
     PhabricatorProjectInterface,
@@ -998,73 +999,6 @@
     return new DifferentialTransaction();
   }
 
-  public function willRenderTimeline(
-    PhabricatorApplicationTransactionView $timeline,
-    AphrontRequest $request) {
-    $viewer = $request->getViewer();
-
-    $render_data = $timeline->getRenderData();
-    $left = $request->getInt('left', idx($render_data, 'left'));
-    $right = $request->getInt('right', idx($render_data, 'right'));
-
-    $diffs = id(new DifferentialDiffQuery())
-      ->setViewer($request->getUser())
-      ->withIDs(array($left, $right))
-      ->execute();
-    $diffs = mpull($diffs, null, 'getID');
-    $left_diff = $diffs[$left];
-    $right_diff = $diffs[$right];
-
-    $old_ids = $request->getStr('old', idx($render_data, 'old'));
-    $new_ids = $request->getStr('new', idx($render_data, 'new'));
-    $old_ids = array_filter(explode(',', $old_ids));
-    $new_ids = array_filter(explode(',', $new_ids));
-
-    $type_inline = DifferentialTransaction::TYPE_INLINE;
-    $changeset_ids = array_merge($old_ids, $new_ids);
-    $inlines = array();
-    foreach ($timeline->getTransactions() as $xaction) {
-      if ($xaction->getTransactionType() == $type_inline) {
-        $inlines[] = $xaction->getComment();
-        $changeset_ids[] = $xaction->getComment()->getChangesetID();
-      }
-    }
-
-    if ($changeset_ids) {
-      $changesets = id(new DifferentialChangesetQuery())
-        ->setViewer($request->getUser())
-        ->withIDs($changeset_ids)
-        ->execute();
-      $changesets = mpull($changesets, null, 'getID');
-    } else {
-      $changesets = array();
-    }
-
-    foreach ($inlines as $key => $inline) {
-      $inlines[$key] = DifferentialInlineComment::newFromModernComment(
-        $inline);
-    }
-
-    $query = id(new DifferentialInlineCommentQuery())
-      ->needHidden(true)
-      ->setViewer($viewer);
-
-    // NOTE: This is a bit sketchy: this method adjusts the inlines as a
-    // side effect, which means it will ultimately adjust the transaction
-    // comments and affect timeline rendering.
-    $query->adjustInlinesForChangesets(
-      $inlines,
-      array_select_keys($changesets, $old_ids),
-      array_select_keys($changesets, $new_ids),
-      $this);
-
-    return $timeline
-      ->setChangesets($changesets)
-      ->setRevision($this)
-      ->setLeftDiff($left_diff)
-      ->setRightDiff($right_diff);
-  }
-
 
 /* -(  PhabricatorDestructibleInterface  )----------------------------------- */
 
@@ -1206,4 +1140,13 @@
     return new DifferentialRevisionDraftEngine();
   }
 
+
+/* -(  PhabricatorTimelineInterface  )--------------------------------------- */
+
+
+  public function newTimelineEngine() {
+    return new DifferentialRevisionTimelineEngine();
+  }
+
+
 }
diff --git a/src/applications/differential/storage/DifferentialTransaction.php b/src/applications/differential/storage/DifferentialTransaction.php
--- a/src/applications/differential/storage/DifferentialTransaction.php
+++ b/src/applications/differential/storage/DifferentialTransaction.php
@@ -65,10 +65,6 @@
     return new DifferentialTransactionComment();
   }
 
-  public function getApplicationTransactionViewObject() {
-    return new DifferentialTransactionView();
-  }
-
   public function shouldHide() {
     $old = $this->getOldValue();
     $new = $this->getNewValue();
diff --git a/src/applications/diffusion/controller/DiffusionCommitController.php b/src/applications/diffusion/controller/DiffusionCommitController.php
--- a/src/applications/diffusion/controller/DiffusionCommitController.php
+++ b/src/applications/diffusion/controller/DiffusionCommitController.php
@@ -740,8 +740,6 @@
       $commit,
       new PhabricatorAuditTransactionQuery());
 
-    $commit->willRenderTimeline($timeline, $this->getRequest());
-
     $timeline->setQuoteRef($commit->getMonogram());
 
     return $timeline;
diff --git a/src/applications/diffusion/engine/DiffusionCommitTimelineEngine.php b/src/applications/diffusion/engine/DiffusionCommitTimelineEngine.php
new file mode 100644
--- /dev/null
+++ b/src/applications/diffusion/engine/DiffusionCommitTimelineEngine.php
@@ -0,0 +1,30 @@
+<?php
+
+final class DiffusionCommitTimelineEngine
+  extends PhabricatorTimelineEngine {
+
+  protected function newTimelineView() {
+    $xactions = $this->getTransactions();
+
+    $path_ids = array();
+    foreach ($xactions as $xaction) {
+      if ($xaction->hasComment()) {
+        $path_id = $xaction->getComment()->getPathID();
+        if ($path_id) {
+          $path_ids[] = $path_id;
+        }
+      }
+    }
+
+    $path_map = array();
+    if ($path_ids) {
+      $path_map = id(new DiffusionPathQuery())
+        ->withPathIDs($path_ids)
+        ->execute();
+      $path_map = ipull($path_map, 'path', 'id');
+    }
+
+    return id(new PhabricatorAuditTransactionView())
+      ->setPathMap($path_map);
+  }
+}
diff --git a/src/applications/legalpad/storage/LegalpadTransaction.php b/src/applications/legalpad/storage/LegalpadTransaction.php
--- a/src/applications/legalpad/storage/LegalpadTransaction.php
+++ b/src/applications/legalpad/storage/LegalpadTransaction.php
@@ -14,10 +14,6 @@
     return new LegalpadTransactionComment();
   }
 
-  public function getApplicationTransactionViewObject() {
-    return new LegalpadTransactionView();
-  }
-
   public function getBaseTransactionClass() {
     return 'LegalpadDocumentTransactionType';
   }
diff --git a/src/applications/legalpad/view/LegalpadTransactionView.php b/src/applications/legalpad/view/LegalpadTransactionView.php
deleted file mode 100644
--- a/src/applications/legalpad/view/LegalpadTransactionView.php
+++ /dev/null
@@ -1,4 +0,0 @@
-<?php
-
-final class LegalpadTransactionView
-  extends PhabricatorApplicationTransactionView {}
diff --git a/src/applications/pholio/controller/PholioMockCommentController.php b/src/applications/pholio/controller/PholioMockCommentController.php
--- a/src/applications/pholio/controller/PholioMockCommentController.php
+++ b/src/applications/pholio/controller/PholioMockCommentController.php
@@ -68,13 +68,10 @@
     }
 
     if ($request->isAjax() && $is_preview) {
-      $xaction_view = id(new PholioTransactionView())
-        ->setMock($mock);
-
       return id(new PhabricatorApplicationTransactionResponse())
+        ->setObject($mock)
         ->setViewer($viewer)
         ->setTransactions($xactions)
-        ->setTransactionView($xaction_view)
         ->setIsPreview($is_preview);
     } else {
       return id(new AphrontRedirectResponse())->setURI($mock_uri);
diff --git a/src/applications/pholio/engine/PholioMockTimelineEngine.php b/src/applications/pholio/engine/PholioMockTimelineEngine.php
new file mode 100644
--- /dev/null
+++ b/src/applications/pholio/engine/PholioMockTimelineEngine.php
@@ -0,0 +1,19 @@
+<?php
+
+final class PholioMockTimelineEngine
+  extends PhabricatorTimelineEngine {
+
+  protected function newTimelineView() {
+    $viewer = $this->getViewer();
+    $object = $this->getObject();
+
+    PholioMockQuery::loadImages(
+      $viewer,
+      array($object),
+      $need_inline_comments = true);
+
+    return id(new PholioTransactionView())
+      ->setMock($object);
+  }
+
+}
diff --git a/src/applications/pholio/storage/PholioMock.php b/src/applications/pholio/storage/PholioMock.php
--- a/src/applications/pholio/storage/PholioMock.php
+++ b/src/applications/pholio/storage/PholioMock.php
@@ -7,6 +7,7 @@
     PhabricatorTokenReceiverInterface,
     PhabricatorFlaggableInterface,
     PhabricatorApplicationTransactionInterface,
+    PhabricatorTimelineInterface,
     PhabricatorProjectInterface,
     PhabricatorDestructibleInterface,
     PhabricatorSpacesInterface,
@@ -228,17 +229,6 @@
     return new PholioTransaction();
   }
 
-  public function willRenderTimeline(
-    PhabricatorApplicationTransactionView $timeline,
-    AphrontRequest $request) {
-
-    PholioMockQuery::loadImages(
-      $request->getUser(),
-      array($this),
-      $need_inline_comments = true);
-    $timeline->setMock($this);
-    return $timeline;
-  }
 
 /* -(  PhabricatorTokenReceiverInterface  )---------------------------------- */
 
@@ -288,9 +278,18 @@
 
 /* -(  PhabricatorFerretInterface  )----------------------------------------- */
 
+
   public function newFerretEngine() {
     return new PholioMockFerretEngine();
   }
 
 
+/* -(  PhabricatorTimelineInterace  )---------------------------------------- */
+
+
+  public function newTimelineEngine() {
+    return new PholioMockTimelineEngine();
+  }
+
+
 }
diff --git a/src/applications/pholio/storage/PholioTransaction.php b/src/applications/pholio/storage/PholioTransaction.php
--- a/src/applications/pholio/storage/PholioTransaction.php
+++ b/src/applications/pholio/storage/PholioTransaction.php
@@ -23,10 +23,6 @@
     return new PholioTransactionComment();
   }
 
-  public function getApplicationTransactionViewObject() {
-    return new PholioTransactionView();
-  }
-
   public function getMailTags() {
     $tags = array();
     switch ($this->getTransactionType()) {
diff --git a/src/applications/ponder/controller/PonderAnswerCommentController.php b/src/applications/ponder/controller/PonderAnswerCommentController.php
--- a/src/applications/ponder/controller/PonderAnswerCommentController.php
+++ b/src/applications/ponder/controller/PonderAnswerCommentController.php
@@ -50,6 +50,7 @@
 
     if ($request->isAjax() && $is_preview) {
       return id(new PhabricatorApplicationTransactionResponse())
+        ->setObject($answer)
         ->setViewer($viewer)
         ->setTransactions($xactions)
         ->setIsPreview($is_preview);
diff --git a/src/applications/ponder/controller/PonderQuestionCommentController.php b/src/applications/ponder/controller/PonderQuestionCommentController.php
--- a/src/applications/ponder/controller/PonderQuestionCommentController.php
+++ b/src/applications/ponder/controller/PonderQuestionCommentController.php
@@ -46,6 +46,7 @@
 
     if ($request->isAjax() && $is_preview) {
       return id(new PhabricatorApplicationTransactionResponse())
+        ->setObject($question)
         ->setViewer($viewer)
         ->setTransactions($xactions)
         ->setIsPreview($is_preview);
diff --git a/src/applications/releeph/controller/request/ReleephRequestCommentController.php b/src/applications/releeph/controller/request/ReleephRequestCommentController.php
--- a/src/applications/releeph/controller/request/ReleephRequestCommentController.php
+++ b/src/applications/releeph/controller/request/ReleephRequestCommentController.php
@@ -51,6 +51,7 @@
 
     if ($request->isAjax() && $is_preview) {
       return id(new PhabricatorApplicationTransactionResponse())
+        ->setObject($pull)
         ->setViewer($viewer)
         ->setTransactions($xactions)
         ->setIsPreview($is_preview);
diff --git a/src/applications/repository/storage/PhabricatorRepositoryCommit.php b/src/applications/repository/storage/PhabricatorRepositoryCommit.php
--- a/src/applications/repository/storage/PhabricatorRepositoryCommit.php
+++ b/src/applications/repository/storage/PhabricatorRepositoryCommit.php
@@ -14,6 +14,7 @@
     HarbormasterBuildkiteBuildableInterface,
     PhabricatorCustomFieldInterface,
     PhabricatorApplicationTransactionInterface,
+    PhabricatorTimelineInterface,
     PhabricatorFulltextInterface,
     PhabricatorFerretInterface,
     PhabricatorConduitResultInterface,
@@ -738,33 +739,6 @@
     return new PhabricatorAuditTransaction();
   }
 
-  public function willRenderTimeline(
-    PhabricatorApplicationTransactionView $timeline,
-    AphrontRequest $request) {
-
-    $xactions = $timeline->getTransactions();
-
-    $path_ids = array();
-    foreach ($xactions as $xaction) {
-      if ($xaction->hasComment()) {
-        $path_id = $xaction->getComment()->getPathID();
-        if ($path_id) {
-          $path_ids[] = $path_id;
-        }
-      }
-    }
-
-    $path_map = array();
-    if ($path_ids) {
-      $path_map = id(new DiffusionPathQuery())
-        ->withPathIDs($path_ids)
-        ->execute();
-      $path_map = ipull($path_map, 'path', 'id');
-    }
-
-    return $timeline->setPathMap($path_map);
-  }
-
 /* -(  PhabricatorFulltextInterface  )--------------------------------------- */
 
 
@@ -916,4 +890,12 @@
     return $this;
   }
 
+
+/* -(  PhabricatorTimelineInterface  )--------------------------------------- */
+
+
+  public function newTimelineEngine() {
+    return new DiffusionCommitTimelineEngine();
+  }
+
 }
diff --git a/src/applications/slowvote/controller/PhabricatorSlowvoteCommentController.php b/src/applications/slowvote/controller/PhabricatorSlowvoteCommentController.php
--- a/src/applications/slowvote/controller/PhabricatorSlowvoteCommentController.php
+++ b/src/applications/slowvote/controller/PhabricatorSlowvoteCommentController.php
@@ -51,6 +51,7 @@
 
     if ($request->isAjax() && $is_preview) {
       return id(new PhabricatorApplicationTransactionResponse())
+        ->setObject($poll)
         ->setViewer($viewer)
         ->setTransactions($xactions)
         ->setIsPreview($is_preview);
diff --git a/src/applications/transactions/controller/PhabricatorApplicationTransactionShowOlderController.php b/src/applications/transactions/controller/PhabricatorApplicationTransactionShowOlderController.php
--- a/src/applications/transactions/controller/PhabricatorApplicationTransactionShowOlderController.php
+++ b/src/applications/transactions/controller/PhabricatorApplicationTransactionShowOlderController.php
@@ -27,7 +27,18 @@
       return new Aphront404Response();
     }
 
-    $timeline = $this->buildTransactionTimeline($object, $query);
+    $raw_view_data = $request->getStr('viewData');
+    try {
+      $view_data = phutil_json_decode($raw_view_data);
+    } catch (Exception $ex) {
+      $view_data = array();
+    }
+
+    $timeline = $this->buildTransactionTimeline(
+      $object,
+      $query,
+      null,
+      $view_data);
 
     $phui_timeline = $timeline->buildPHUITimelineView($with_hiding = false);
     $phui_timeline->setShouldAddSpacers(false);
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
@@ -1955,6 +1955,7 @@
       $preview_content = $this->newCommentPreviewContent($object, $xactions);
 
       return id(new PhabricatorApplicationTransactionResponse())
+        ->setObject($object)
         ->setViewer($viewer)
         ->setTransactions($xactions)
         ->setIsPreview($is_preview)
diff --git a/src/applications/transactions/engine/PhabricatorStandardTimelineEngine.php b/src/applications/transactions/engine/PhabricatorStandardTimelineEngine.php
new file mode 100644
--- /dev/null
+++ b/src/applications/transactions/engine/PhabricatorStandardTimelineEngine.php
@@ -0,0 +1,4 @@
+<?php
+
+final class PhabricatorStandardTimelineEngine
+   extends PhabricatorTimelineEngine {}
diff --git a/src/applications/transactions/engine/PhabricatorTimelineEngine.php b/src/applications/transactions/engine/PhabricatorTimelineEngine.php
new file mode 100644
--- /dev/null
+++ b/src/applications/transactions/engine/PhabricatorTimelineEngine.php
@@ -0,0 +1,95 @@
+<?php
+
+abstract class PhabricatorTimelineEngine
+  extends Phobject {
+
+  private $viewer;
+  private $object;
+  private $xactions;
+  private $viewData;
+
+  final public static function newForObject($object) {
+    if ($object instanceof PhabricatorTimelineInterface) {
+      $engine = $object->newTimelineEngine();
+    } else {
+      $engine = new PhabricatorStandardTimelineEngine();
+    }
+
+    $engine->setObject($object);
+
+    return $engine;
+  }
+
+  final public function setViewer(PhabricatorUser $viewer) {
+    $this->viewer = $viewer;
+    return $this;
+  }
+
+  final public function getViewer() {
+    return $this->viewer;
+  }
+
+  final public function setObject($object) {
+    $this->object = $object;
+    return $this;
+  }
+
+  final public function getObject() {
+    return $this->object;
+  }
+
+  final public function setTransactions(array $xactions) {
+    assert_instances_of($xactions, 'PhabricatorApplicationTransaction');
+    $this->xactions = $xactions;
+    return $this;
+  }
+
+  final public function getTransactions() {
+    return $this->xactions;
+  }
+
+  final public function setRequest(AphrontRequest $request) {
+    $this->request = $request;
+    return $this;
+  }
+
+  final public function getRequest() {
+    return $this->request;
+  }
+
+  final public function setViewData(array $view_data) {
+    $this->viewData = $view_data;
+    return $this;
+  }
+
+  final public function getViewData() {
+    return $this->viewData;
+  }
+
+  final public function buildTimelineView() {
+    $view = $this->newTimelineView();
+
+    if (!($view instanceof PhabricatorApplicationTransactionView)) {
+      throw new Exception(
+        pht(
+          'Expected "newTimelineView()" to return an object of class "%s" '.
+          '(in engine "%s").',
+          'PhabricatorApplicationTransactionView',
+          get_class($this)));
+    }
+
+    $viewer = $this->getViewer();
+    $object = $this->getObject();
+    $xactions = $this->getTransactions();
+
+    return $view
+      ->setViewer($viewer)
+      ->setObjectPHID($object->getPHID())
+      ->setTransactions($xactions);
+  }
+
+  protected function newTimelineView() {
+    return new PhabricatorApplicationTransactionView();
+  }
+
+}
diff --git a/src/applications/transactions/interface/PhabricatorApplicationTransactionInterface.php b/src/applications/transactions/interface/PhabricatorApplicationTransactionInterface.php
--- a/src/applications/transactions/interface/PhabricatorApplicationTransactionInterface.php
+++ b/src/applications/transactions/interface/PhabricatorApplicationTransactionInterface.php
@@ -35,15 +35,6 @@
    */
   public function getApplicationTransactionTemplate();
 
-  /**
-   * Hook to augment the $timeline with additional data for rendering.
-   *
-   * @return PhabricatorApplicationTransactionView
-   */
-  public function willRenderTimeline(
-    PhabricatorApplicationTransactionView $timeline,
-    AphrontRequest $request);
-
 }
 
 // TEMPLATE IMPLEMENTATION /////////////////////////////////////////////////////
@@ -64,11 +55,4 @@
     return new <<<???>>>Transaction();
   }
 
-  public function willRenderTimeline(
-    PhabricatorApplicationTransactionView $timeline,
-    AphrontRequest $request) {
-
-    return $timeline;
-  }
-
 */
diff --git a/src/applications/transactions/interface/PhabricatorTimelineInterface.php b/src/applications/transactions/interface/PhabricatorTimelineInterface.php
new file mode 100644
--- /dev/null
+++ b/src/applications/transactions/interface/PhabricatorTimelineInterface.php
@@ -0,0 +1,7 @@
+<?php
+
+interface PhabricatorTimelineInterface {
+
+  public function newTimelineEngine();
+
+}
diff --git a/src/applications/transactions/response/PhabricatorApplicationTransactionResponse.php b/src/applications/transactions/response/PhabricatorApplicationTransactionResponse.php
--- a/src/applications/transactions/response/PhabricatorApplicationTransactionResponse.php
+++ b/src/applications/transactions/response/PhabricatorApplicationTransactionResponse.php
@@ -6,17 +6,8 @@
   private $viewer;
   private $transactions;
   private $isPreview;
-  private $transactionView;
   private $previewContent;
-
-  public function setTransactionView($transaction_view) {
-    $this->transactionView = $transaction_view;
-    return $this;
-  }
-
-  public function getTransactionView() {
-    return $this->transactionView;
-  }
+  private $object;
 
   protected function buildProxy() {
     return new AphrontAjaxResponse();
@@ -33,6 +24,15 @@
     return $this->transactions;
   }
 
+  public function setObject($object) {
+    $this->object = $object;
+    return $this;
+  }
+
+  public function getObject() {
+    return $this->object;
+  }
+
   public function setViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
     return $this;
@@ -57,19 +57,17 @@
   }
 
   public function reduceProxyResponse() {
-    if ($this->transactionView) {
-      $view = $this->transactionView;
-    } else if ($this->getTransactions()) {
-      $view = head($this->getTransactions())
-        ->getApplicationTransactionViewObject();
-    } else {
-      $view = new PhabricatorApplicationTransactionView();
-    }
+    $object = $this->getObject();
+    $viewer = $this->getViewer();
+    $xactions = $this->getTransactions();
+
+    $timeline_engine = PhabricatorTimelineEngine::newForObject($object)
+      ->setViewer($viewer)
+      ->setTransactions($xactions);
+
+    $view = $timeline_engine->buildTimelineView();
 
-    $view
-      ->setUser($this->getViewer())
-      ->setTransactions($this->getTransactions())
-      ->setIsPreview($this->isPreview);
+    $view->setIsPreview($this->isPreview);
 
     if ($this->isPreview) {
       $xactions = mpull($view->buildEvents(), 'render');
diff --git a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
--- a/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
+++ b/src/applications/transactions/storage/PhabricatorApplicationTransaction.php
@@ -79,10 +79,6 @@
     throw new PhutilMethodNotImplementedException();
   }
 
-  public function getApplicationTransactionViewObject() {
-    return new PhabricatorApplicationTransactionView();
-  }
-
   public function getMetadataValue($key, $default = null) {
     return idx($this->metadata, $key, $default);
   }
diff --git a/src/applications/transactions/view/PhabricatorApplicationTransactionView.php b/src/applications/transactions/view/PhabricatorApplicationTransactionView.php
--- a/src/applications/transactions/view/PhabricatorApplicationTransactionView.php
+++ b/src/applications/transactions/view/PhabricatorApplicationTransactionView.php
@@ -15,8 +15,8 @@
   private $quoteRef;
   private $pager;
   private $renderAsFeed;
-  private $renderData = array();
   private $hideCommentOptions = false;
+  private $viewData = array();
 
   public function setRenderAsFeed($feed) {
     $this->renderAsFeed = $feed;
@@ -97,28 +97,22 @@
     return $this->pager;
   }
 
-  /**
-   * This is additional data that may be necessary to render the next set
-   * of transactions. Objects that implement
-   * PhabricatorApplicationTransactionInterface use this data in
-   * willRenderTimeline.
-   */
-  public function setRenderData(array $data) {
-    $this->renderData = $data;
+  public function setHideCommentOptions($hide_comment_options) {
+    $this->hideCommentOptions = $hide_comment_options;
     return $this;
   }
 
-  public function getRenderData() {
-    return $this->renderData;
+  public function getHideCommentOptions() {
+    return $this->hideCommentOptions;
   }
 
-  public function setHideCommentOptions($hide_comment_options) {
-    $this->hideCommentOptions = $hide_comment_options;
+  public function setViewData(array $view_data) {
+    $this->viewData = $view_data;
     return $this;
   }
 
-  public function getHideCommentOptions() {
-    return $this->hideCommentOptions;
+  public function getViewData() {
+    return $this->viewData;
   }
 
   public function buildEvents($with_hiding = false) {
@@ -216,10 +210,11 @@
     }
 
     $view = id(new PHUITimelineView())
-      ->setUser($this->getUser())
+      ->setViewer($this->getViewer())
       ->setShouldTerminate($this->shouldTerminate)
       ->setQuoteTargetID($this->getQuoteTargetID())
-      ->setQuoteRef($this->getQuoteRef());
+      ->setQuoteRef($this->getQuoteRef())
+      ->setViewData($this->getViewData());
 
     $events = $this->buildEvents($with_hiding);
     foreach ($events as $event) {
@@ -230,10 +225,6 @@
       $view->setPager($this->getPager());
     }
 
-    if ($this->getRenderData()) {
-      $view->setRenderData($this->getRenderData());
-    }
-
     return $view;
   }
 
@@ -246,7 +237,7 @@
       $field = PhabricatorApplicationTransactionComment::MARKUP_FIELD_COMMENT;
 
       $engine = id(new PhabricatorMarkupEngine())
-        ->setViewer($this->getUser());
+        ->setViewer($this->getViewer());
       foreach ($this->transactions as $xaction) {
         if (!$xaction->hasComment()) {
           continue;
@@ -414,10 +405,10 @@
   private function renderEvent(
     PhabricatorApplicationTransaction $xaction,
     array $group) {
-    $viewer = $this->getUser();
+    $viewer = $this->getViewer();
 
     $event = id(new PHUITimelineEventView())
-      ->setUser($viewer)
+      ->setViewer($viewer)
       ->setAuthorPHID($xaction->getAuthorPHID())
       ->setTransactionPHID($xaction->getPHID())
       ->setUserHandle($xaction->getHandle($xaction->getAuthorPHID()))
diff --git a/src/view/phui/PHUITimelineView.php b/src/view/phui/PHUITimelineView.php
--- a/src/view/phui/PHUITimelineView.php
+++ b/src/view/phui/PHUITimelineView.php
@@ -7,7 +7,7 @@
   private $shouldTerminate = false;
   private $shouldAddSpacers = true;
   private $pager;
-  private $renderData = array();
+  private $viewData = array();
   private $quoteTargetID;
   private $quoteRef;
 
@@ -40,11 +40,15 @@
     return $this;
   }
 
-  public function setRenderData(array $data) {
-    $this->renderData = $data;
+  public function setViewData(array $data) {
+    $this->viewData = $data;
     return $this;
   }
 
+  public function getViewData() {
+    return $this->viewData;
+  }
+
   public function setQuoteTargetID($quote_target_id) {
     $this->quoteTargetID = $quote_target_id;
     return $this;
@@ -72,7 +76,7 @@
         'phabricator-show-older-transactions',
         array(
           'timelineID' => $this->id,
-          'renderData' => $this->renderData,
+          'viewData' => $this->getViewData(),
         ));
     }
     $events = $this->buildEvents();
diff --git a/webroot/rsrc/js/application/transactions/behavior-show-older-transactions.js b/webroot/rsrc/js/application/transactions/behavior-show-older-transactions.js
--- a/webroot/rsrc/js/application/transactions/behavior-show-older-transactions.js
+++ b/webroot/rsrc/js/application/transactions/behavior-show-older-transactions.js
@@ -83,7 +83,11 @@
   };
 
   var fetch_older_workflow = function(href, callback, swap) {
-    return new JX.Workflow(href, config.renderData)
+    var params = {
+      viewData: JX.JSON.stringify(config.viewData)
+    };
+
+    return new JX.Workflow(href, params)
       .setHandler(JX.bind(null, callback, swap));
   };