Index: src/aphront/AphrontController.php
===================================================================
--- src/aphront/AphrontController.php
+++ src/aphront/AphrontController.php
@@ -9,7 +9,6 @@
   private $currentApplication;
   private $delegatingController;
 
-
   public function setDelegatingController(
     AphrontController $delegating_controller) {
     $this->delegatingController = $delegating_controller;
@@ -64,4 +63,24 @@
     return $this->currentApplication;
   }
 
+  public function getDefaultResourceSource() {
+    throw new Exception(
+      pht(
+        'A Controller must implement getDefaultResourceSource() before you '.
+        'can invoke requireResource() or initBehavior().'));
+  }
+
+  public function requireResource($symbol) {
+    $response = CelerityAPI::getStaticResourceResponse();
+    $response->requireResource($symbol, $this->getDefaultResourceSource());
+    return $this;
+  }
+
+  public function initBehavior($name, $config = array()) {
+    Javelin::initBehavior(
+      $name,
+      $config,
+      $this->getDefaultResourceSource());
+  }
+
 }
Index: src/applications/base/controller/PhabricatorController.php
===================================================================
--- src/applications/base/controller/PhabricatorController.php
+++ src/applications/base/controller/PhabricatorController.php
@@ -408,4 +408,9 @@
     return array($can_act, $message);
   }
 
+  public function getDefaultResourceSource() {
+    return 'phabricator';
+  }
+
+
 }
Index: src/applications/differential/controller/DifferentialRevisionViewController.php
===================================================================
--- src/applications/differential/controller/DifferentialRevisionViewController.php
+++ src/applications/differential/controller/DifferentialRevisionViewController.php
@@ -497,8 +497,8 @@
       );
     }
 
-    require_celerity_resource('phabricator-object-selector-css');
-    require_celerity_resource('javelin-behavior-phabricator-object-selector');
+    $this->requireResource('phabricator-object-selector-css');
+    $this->requireResource('javelin-behavior-phabricator-object-selector');
 
     $links[] = array(
       'icon'  => 'link',
Index: src/applications/differential/view/DifferentialAddCommentView.php
===================================================================
--- src/applications/differential/view/DifferentialAddCommentView.php
+++ src/applications/differential/view/DifferentialAddCommentView.php
@@ -48,7 +48,7 @@
 
   public function render() {
 
-    require_celerity_resource('differential-revision-add-comment-css');
+    $this->requireResource('differential-revision-add-comment-css');
 
     $is_serious = PhabricatorEnv::getEnvConfig('phabricator.serious-business');
 
Index: src/applications/differential/view/DifferentialChangesetDetailView.php
===================================================================
--- src/applications/differential/view/DifferentialChangesetDetailView.php
+++ src/applications/differential/view/DifferentialChangesetDetailView.php
@@ -94,8 +94,8 @@
   }
 
   public function render() {
-    require_celerity_resource('differential-changeset-view-css');
-    require_celerity_resource('syntax-highlighting-css');
+    $this->requireResource('differential-changeset-view-css');
+    $this->requireResource('syntax-highlighting-css');
 
     Javelin::initBehavior('phabricator-oncopy', array());
 
Index: src/applications/differential/view/DifferentialChangesetListView.php
===================================================================
--- src/applications/differential/view/DifferentialChangesetListView.php
+++ src/applications/differential/view/DifferentialChangesetListView.php
@@ -103,7 +103,7 @@
   }
 
   public function render() {
-    require_celerity_resource('differential-changeset-view-css');
+    $this->requireResource('differential-changeset-view-css');
 
     $changesets = $this->changesets;
 
@@ -183,20 +183,20 @@
       $output[] = $detail->render();
     }
 
-    require_celerity_resource('aphront-tooltip-css');
+    $this->requireResource('aphront-tooltip-css');
 
-    Javelin::initBehavior('differential-populate', array(
+    $this->initBehavior('differential-populate', array(
       'registry'    => $mapping,
       'whitespace'  => $this->whitespace,
       'uri'         => $this->renderURI,
     ));
 
-    Javelin::initBehavior('differential-show-more', array(
+    $this->initBehavior('differential-show-more', array(
       'uri' => $this->renderURI,
       'whitespace' => $this->whitespace,
     ));
 
-    Javelin::initBehavior('differential-comment-jump', array());
+    $this->initBehavior('differential-comment-jump', array());
 
     if ($this->inlineURI) {
       $undo_templates = $this->renderUndoTemplates();
Index: src/applications/differential/view/DifferentialDiffTableOfContentsView.php
===================================================================
--- src/applications/differential/view/DifferentialDiffTableOfContentsView.php
+++ src/applications/differential/view/DifferentialDiffTableOfContentsView.php
@@ -54,8 +54,8 @@
 
   public function render() {
 
-    require_celerity_resource('differential-core-view-css');
-    require_celerity_resource('differential-table-of-contents-css');
+    $this->requireResource('differential-core-view-css');
+    $this->requireResource('differential-table-of-contents-css');
 
     $rows = array();
 
Index: src/applications/differential/view/DifferentialLocalCommitsView.php
===================================================================
--- src/applications/differential/view/DifferentialLocalCommitsView.php
+++ src/applications/differential/view/DifferentialLocalCommitsView.php
@@ -20,7 +20,7 @@
       return null;
     }
 
-    require_celerity_resource('differential-local-commits-view-css');
+    $this->requireResource('differential-local-commits-view-css');
 
     $has_tree = false;
     $has_local = false;
Index: src/applications/differential/view/DifferentialResultsTableView.php
===================================================================
--- src/applications/differential/view/DifferentialResultsTableView.php
+++ src/applications/differential/view/DifferentialResultsTableView.php
@@ -97,10 +97,10 @@
         ),
         phutil_tag('th', array('colspan' => 2), $hide_more));
 
-      Javelin::initBehavior('differential-show-field-details');
+      $this->initBehavior('differential-show-field-details');
     }
 
-    require_celerity_resource('differential-results-table-css');
+    $this->requireResource('differential-results-table-css');
 
     return javelin_tag(
       'table',
Index: src/applications/differential/view/DifferentialRevisionCommentListView.php
===================================================================
--- src/applications/differential/view/DifferentialRevisionCommentListView.php
+++ src/applications/differential/view/DifferentialRevisionCommentListView.php
@@ -53,7 +53,7 @@
 
   public function render() {
 
-    require_celerity_resource('differential-revision-comment-list-css');
+    $this->requireResource('differential-revision-comment-list-css');
 
     $engine = new PhabricatorMarkupEngine();
     $engine->setViewer($this->user);
@@ -154,7 +154,7 @@
     $visible = array_reverse($visible);
 
     if ($hidden) {
-      Javelin::initBehavior(
+      $this->initBehavior(
         'differential-show-all-comments',
         array(
           'markup' => implode("\n", $hidden),
Index: src/applications/differential/view/DifferentialRevisionCommentView.php
===================================================================
--- src/applications/differential/view/DifferentialRevisionCommentView.php
+++ src/applications/differential/view/DifferentialRevisionCommentView.php
@@ -67,8 +67,8 @@
       throw new Exception("Call setUser() before rendering!");
     }
 
-    require_celerity_resource('phabricator-remarkup-css');
-    require_celerity_resource('differential-revision-comment-css');
+    $this->requireResource('phabricator-remarkup-css');
+    $this->requireResource('differential-revision-comment-css');
 
     $comment = $this->comment;
 
Index: src/applications/differential/view/DifferentialRevisionDetailView.php
===================================================================
--- src/applications/differential/view/DifferentialRevisionDetailView.php
+++ src/applications/differential/view/DifferentialRevisionDetailView.php
@@ -45,7 +45,7 @@
 
   public function render() {
 
-    require_celerity_resource('differential-core-view-css');
+    $this->requireResource('differential-core-view-css');
 
     $revision = $this->revision;
     $user = $this->getUser();
Index: src/applications/differential/view/DifferentialRevisionListView.php
===================================================================
--- src/applications/differential/view/DifferentialRevisionListView.php
+++ src/applications/differential/view/DifferentialRevisionListView.php
@@ -102,8 +102,8 @@
         -$stale);
     }
 
-    Javelin::initBehavior('phabricator-tooltips', array());
-    require_celerity_resource('aphront-tooltip-css');
+    $this->initBehavior('phabricator-tooltips', array());
+    $this->requireResource('aphront-tooltip-css');
 
     $flagged = mpull($this->flags, null, 'getObjectPHID');
 
Index: src/applications/differential/view/DifferentialRevisionUpdateHistoryView.php
===================================================================
--- src/applications/differential/view/DifferentialRevisionUpdateHistoryView.php
+++ src/applications/differential/view/DifferentialRevisionUpdateHistoryView.php
@@ -30,8 +30,8 @@
 
   public function render() {
 
-    require_celerity_resource('differential-core-view-css');
-    require_celerity_resource('differential-revision-history-css');
+    $this->requireResource('differential-core-view-css');
+    $this->requireResource('differential-revision-history-css');
 
     $data = array(
       array(
Index: src/infrastructure/celerity/CelerityResourceMap.php
===================================================================
--- src/infrastructure/celerity/CelerityResourceMap.php
+++ src/infrastructure/celerity/CelerityResourceMap.php
@@ -236,4 +236,8 @@
     return isset($this->packageMap[$name]);
   }
 
+  public function getResourceTypeForName($name) {
+    return $this->resources->getResourceType($name);
+  }
+
 }
Index: src/infrastructure/celerity/CelerityStaticResourceResponse.php
===================================================================
--- src/infrastructure/celerity/CelerityStaticResourceResponse.php
+++ src/infrastructure/celerity/CelerityStaticResourceResponse.php
@@ -39,8 +39,12 @@
    * a behavior will execute only once even if it is initialized multiple times.
    * If $config is nonempty, the behavior will be invoked once for each config.
    */
-  public function initBehavior($behavior, array $config = array()) {
-    $this->requireResource('javelin-behavior-'.$behavior);
+  public function initBehavior(
+    $behavior,
+    array $config = array(),
+    $source_name = 'phabricator') {
+
+    $this->requireResource('javelin-behavior-'.$behavior, $source_name);
 
     if (empty($this->behaviors[$behavior])) {
       $this->behaviors[$behavior] = array();
@@ -53,19 +57,39 @@
     return $this;
   }
 
-  public function requireResource($symbol) {
-    $this->symbols[$symbol] = true;
+  public function requireResource($symbol, $source_name) {
+    if (isset($this->symbols[$source_name][$symbol])) {
+      return $this;
+    }
+
+    // Verify that the resource exists.
+    $map = CelerityResourceMap::getNamedInstance($source_name);
+    $name = $map->getResourceNameForSymbol($symbol);
+    if ($name === null) {
+      throw new Exception(
+        pht(
+          'No resource with symbol "%s" exists in source "%s"!',
+          $symbol,
+          $source_name));
+    }
+
+    $this->symbols[$source_name][$symbol] = true;
     $this->needsResolve = true;
+
     return $this;
   }
 
   private function resolveResources() {
     if ($this->needsResolve) {
-      $map = CelerityResourceMap::getNamedInstance('phabricator');
+      $this->packaged = array();
+      foreach ($this->symbols as $source_name => $symbols_map) {
+        $symbols = array_keys($symbols_map);
 
-      $symbols = array_keys($this->symbols);
-      $this->packaged = $map->getPackagedNamesForSymbols($symbols);
+        $map = CelerityResourceMap::getNamedInstance($source_name);
+        $packaged = $map->getPackagedNamesForSymbols($symbols);
 
+        $this->packaged[$source_name] = $packaged;
+      }
       $this->needsResolve = false;
     }
     return $this;
@@ -74,24 +98,34 @@
   public function renderSingleResource($symbol, $source_name) {
     $map = CelerityResourceMap::getNamedInstance($source_name);
     $packaged = $map->getPackagedNamesForSymbols(array($symbol));
-    return $this->renderPackagedResources($packaged);
+    return $this->renderPackagedResources($map, $packaged);
   }
 
   public function renderResourcesOfType($type) {
     $this->resolveResources();
 
-    $resources = array();
-    foreach ($this->packaged as $name) {
-      $resource_type = CelerityResourceTransformer::getResourceType($name);
-      if ($resource_type == $type) {
-        $resources[] = $name;
+    $result = array();
+    foreach ($this->packaged as $source_name => $resource_names) {
+      $map = CelerityResourceMap::getNamedInstance($source_name);
+
+      $resources_of_type = array();
+      foreach ($resource_names as $resource_name) {
+        $resource_type = $map->getResourceTypeForName($resource_name);
+        if ($resource_type == $type) {
+          $resources_of_type[] = $resource_name;
+        }
       }
+
+      $result[] = $this->renderPackagedResources($map, $resources_of_type);
     }
 
-    return $this->renderPackagedResources($resources);
+    return phutil_implode_html('', $result);
   }
 
-  private function renderPackagedResources(array $resources) {
+  private function renderPackagedResources(
+    CelerityResourceMap $map,
+    array $resources) {
+
     $output = array();
     foreach ($resources as $name) {
       if (isset($this->hasRendered[$name])) {
@@ -99,15 +133,19 @@
       }
       $this->hasRendered[$name] = true;
 
-      $output[] = $this->renderResource($name);
-      $output[] = "\n";
+      $output[] = $this->renderResource($map, $name);
     }
-    return phutil_implode_html('', $output);
+
+    return $output;
   }
 
-  private function renderResource($name) {
-    $uri = $this->getURI($name);
-    $type = CelerityResourceTransformer::getResourceType($name);
+  private function renderResource(
+    CelerityResourceMap $map,
+    $name) {
+
+    $uri = $this->getURI($map, $name);
+    $type = $map->getResourceTypeForName($name);
+
     switch ($type) {
       case 'css':
         return phutil_tag(
@@ -126,7 +164,12 @@
           ),
           '');
     }
-    throw new Exception("Unable to render resource.");
+
+    throw new Exception(
+      pht(
+        'Unable to render resource "%s", which has unknown type "%s".',
+        $name,
+        $type));
   }
 
   public function renderHTMLFooter() {
@@ -225,8 +268,11 @@
 
     $this->resolveResources();
     $resources = array();
-    foreach ($this->packaged as $resource) {
-      $resources[] = $this->getURI($resource);
+    foreach ($this->packaged as $source_name => $resource_names) {
+      $map = CelerityResourceMap::getNamedInstance($source_name);
+      foreach ($resource_names as $resource_name) {
+        $resources[] = $this->getURI($map, $resource_name);
+      }
     }
     if ($resources) {
       $response['javelin_resources'] = $resources;
@@ -235,8 +281,10 @@
     return $response;
   }
 
-  private function getURI($name) {
-    $map = CelerityResourceMap::getNamedInstance('phabricator');
+  private function getURI(
+    CelerityResourceMap $map,
+    $name) {
+
     $uri = $map->getURIForName($name);
 
     // In developer mode, we dump file modification times into the URI. When a
Index: src/infrastructure/celerity/api.php
===================================================================
--- src/infrastructure/celerity/api.php
+++ src/infrastructure/celerity/api.php
@@ -15,9 +15,9 @@
  *
  * @group celerity
  */
-function require_celerity_resource($symbol) {
+function require_celerity_resource($symbol, $source_name = 'phabricator') {
   $response = CelerityAPI::getStaticResourceResponse();
-  $response->requireResource($symbol);
+  $response->requireResource($symbol, $source_name);
 }
 
 
Index: src/view/AphrontView.php
===================================================================
--- src/view/AphrontView.php
+++ src/view/AphrontView.php
@@ -128,6 +128,23 @@
     return $children;
   }
 
+  public function getDefaultResourceSource() {
+    return 'phabricator';
+  }
+
+  public function requireResource($symbol) {
+    $response = CelerityAPI::getStaticResourceResponse();
+    $response->requireResource($symbol, $this->getDefaultResourceSource());
+    return $this;
+  }
+
+  public function initBehavior($name, $config = array()) {
+    Javelin::initBehavior(
+      $name,
+      $config,
+      $this->getDefaultResourceSource());
+  }
+
 
 /* -(  Rendering  )---------------------------------------------------------- */