Index: src/__phutil_library_map__.php
===================================================================
--- src/__phutil_library_map__.php
+++ src/__phutil_library_map__.php
@@ -1163,6 +1163,7 @@
     'PhabricatorApplicationTransactionValidationException' => 'applications/transactions/exception/PhabricatorApplicationTransactionValidationException.php',
     'PhabricatorApplicationTransactionView' => 'applications/transactions/view/PhabricatorApplicationTransactionView.php',
     'PhabricatorApplicationTransactions' => 'applications/transactions/application/PhabricatorApplicationTransactions.php',
+    'PhabricatorApplicationTypeahead' => 'applications/typeahead/application/PhabricatorApplicationTypeahead.php',
     'PhabricatorApplicationUIExamples' => 'applications/uiexample/application/PhabricatorApplicationUIExamples.php',
     'PhabricatorApplicationUninstallController' => 'applications/meta/controller/PhabricatorApplicationUninstallController.php',
     'PhabricatorApplicationXHProf' => 'applications/xhprof/application/PhabricatorApplicationXHProf.php',
@@ -2120,8 +2121,13 @@
     'PhabricatorTrivialTestCase' => 'infrastructure/testing/__tests__/PhabricatorTrivialTestCase.php',
     'PhabricatorTwoColumnExample' => 'applications/uiexample/examples/PhabricatorTwoColumnExample.php',
     'PhabricatorTypeaheadCommonDatasourceController' => 'applications/typeahead/controller/PhabricatorTypeaheadCommonDatasourceController.php',
+    'PhabricatorTypeaheadCompositeDatasource' => 'applications/typeahead/datasource/PhabricatorTypeaheadCompositeDatasource.php',
+    'PhabricatorTypeaheadDatasource' => 'applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php',
     'PhabricatorTypeaheadDatasourceController' => 'applications/typeahead/controller/PhabricatorTypeaheadDatasourceController.php',
+    'PhabricatorTypeaheadModularDatasourceController' => 'applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php',
+    'PhabricatorTypeaheadMonogramDatasource' => 'applications/typeahead/datasource/PhabricatorTypeaheadMonogramDatasource.php',
     'PhabricatorTypeaheadResult' => 'applications/typeahead/storage/PhabricatorTypeaheadResult.php',
+    'PhabricatorTypeaheadRuntimeCompositeDatasource' => 'applications/typeahead/datasource/PhabricatorTypeaheadRuntimeCompositeDatasource.php',
     'PhabricatorUIConfigOptions' => 'applications/config/option/PhabricatorUIConfigOptions.php',
     'PhabricatorUIExample' => 'applications/uiexample/examples/PhabricatorUIExample.php',
     'PhabricatorUIExampleRenderController' => 'applications/uiexample/controller/PhabricatorUIExampleRenderController.php',
@@ -3801,6 +3807,7 @@
     'PhabricatorApplicationTransactionValidationException' => 'Exception',
     'PhabricatorApplicationTransactionView' => 'AphrontView',
     'PhabricatorApplicationTransactions' => 'PhabricatorApplication',
+    'PhabricatorApplicationTypeahead' => 'PhabricatorApplication',
     'PhabricatorApplicationUIExamples' => 'PhabricatorApplication',
     'PhabricatorApplicationUninstallController' => 'PhabricatorApplicationsController',
     'PhabricatorApplicationXHProf' => 'PhabricatorApplication',
@@ -4896,7 +4903,12 @@
     'PhabricatorTrivialTestCase' => 'PhabricatorTestCase',
     'PhabricatorTwoColumnExample' => 'PhabricatorUIExample',
     'PhabricatorTypeaheadCommonDatasourceController' => 'PhabricatorTypeaheadDatasourceController',
+    'PhabricatorTypeaheadCompositeDatasource' => 'PhabricatorTypeaheadDatasource',
+    'PhabricatorTypeaheadDatasource' => 'Phobject',
     'PhabricatorTypeaheadDatasourceController' => 'PhabricatorController',
+    'PhabricatorTypeaheadModularDatasourceController' => 'PhabricatorTypeaheadDatasourceController',
+    'PhabricatorTypeaheadMonogramDatasource' => 'PhabricatorTypeaheadDatasource',
+    'PhabricatorTypeaheadRuntimeCompositeDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'PhabricatorUIConfigOptions' => 'PhabricatorApplicationConfigOptions',
     'PhabricatorUIExampleRenderController' => 'PhabricatorController',
     'PhabricatorUIListFilterExample' => 'PhabricatorUIExample',
Index: src/aphront/configuration/AphrontDefaultApplicationConfiguration.php
===================================================================
--- src/aphront/configuration/AphrontDefaultApplicationConfiguration.php
+++ src/aphront/configuration/AphrontDefaultApplicationConfiguration.php
@@ -16,11 +16,6 @@
 
   public function getURIMap() {
     return $this->getResourceURIMapRules() + array(
-      '/typeahead/' => array(
-        'common/(?P<type>\w+)/'
-          => 'PhabricatorTypeaheadCommonDatasourceController',
-      ),
-
       '/oauthserver/' => array(
         'auth/'          => 'PhabricatorOAuthServerAuthController',
         'test/'          => 'PhabricatorOAuthServerTestController',
Index: src/applications/typeahead/application/PhabricatorApplicationTypeahead.php
===================================================================
--- /dev/null
+++ src/applications/typeahead/application/PhabricatorApplicationTypeahead.php
@@ -0,0 +1,24 @@
+<?php
+
+final class PhabricatorApplicationTypeahead extends PhabricatorApplication {
+
+  public function getRoutes() {
+    return array(
+      '/typeahead/' => array(
+        'common/(?P<type>\w+)/'
+          => 'PhabricatorTypeaheadCommonDatasourceController',
+        'class/(?:(?P<class>\w+)/)?'
+          => 'PhabricatorTypeaheadModularDatasourceController',
+      ),
+    );
+  }
+
+  public function shouldAppearInLaunchView() {
+    return false;
+  }
+
+  public function canUninstall() {
+    return false;
+  }
+
+}
Index: src/applications/typeahead/controller/PhabricatorTypeaheadCommonDatasourceController.php
===================================================================
--- src/applications/typeahead/controller/PhabricatorTypeaheadCommonDatasourceController.php
+++ src/applications/typeahead/controller/PhabricatorTypeaheadCommonDatasourceController.php
@@ -14,7 +14,6 @@
   }
 
   public function processRequest() {
-
     $request = $this->getRequest();
     $viewer = $request->getUser();
     $query = $request->getStr('q');
Index: src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php
===================================================================
--- /dev/null
+++ src/applications/typeahead/controller/PhabricatorTypeaheadModularDatasourceController.php
@@ -0,0 +1,113 @@
+<?php
+
+final class PhabricatorTypeaheadModularDatasourceController
+  extends PhabricatorTypeaheadDatasourceController {
+
+  private $class;
+
+  public function shouldAllowPublic() {
+    return true;
+  }
+
+  public function willProcessRequest(array $data) {
+    $this->class = idx($data, 'class');
+  }
+
+  public function processRequest() {
+    $request = $this->getRequest();
+    $viewer = $request->getUser();
+    $query = $request->getStr('q');
+
+    // Default this to the query string to make debugging a little bit easier.
+    $raw_query = nonempty($request->getStr('raw'), $query);
+
+    // This makes form submission easier in the debug view.
+    $this->class = nonempty($request->getStr('class'), $this->class);
+
+    $sources = id(new PhutilSymbolLoader())
+      ->setAncestorClass('PhabricatorTypeaheadDatasource')
+      ->loadObjects();
+
+    if (isset($sources[$this->class])) {
+      $source = $sources[$this->class];
+
+      $composite = new PhabricatorTypeaheadRuntimeCompositeDatasource();
+      $composite->addDatasource($source);
+
+      $composite
+        ->setViewer($viewer)
+        ->setQuery($query)
+        ->setRawQuery($raw_query);
+
+      $results = $composite->loadResults();
+    } else {
+      $results = array();
+    }
+
+    $content = mpull($results, 'getWireFormat');
+
+    if ($request->isAjax()) {
+      return id(new AphrontAjaxResponse())->setContent($content);
+    }
+
+    // If there's a non-Ajax request to this endpoint, show results in a tabular
+    // format to make it easier to debug typeahead output.
+
+    $options = array_fuse(array_keys($sources));
+    asort($options);
+
+    $form = id(new AphrontFormView())
+      ->setUser($viewer)
+      ->setAction('/typeahead/class/')
+      ->appendChild(
+        id(new AphrontFormSelectControl())
+          ->setLabel(pht('Source Class'))
+          ->setName('class')
+          ->setValue($this->class)
+          ->setOptions($options))
+      ->appendChild(
+        id(new AphrontFormTextControl())
+          ->setLabel(pht('Query'))
+          ->setName('q')
+          ->setValue($request->getStr('q')))
+      ->appendChild(
+        id(new AphrontFormTextControl())
+          ->setLabel(pht('Raw Query'))
+          ->setName('raw')
+          ->setValue($request->getStr('raw')))
+      ->appendChild(
+        id(new AphrontFormSubmitControl())
+          ->setValue(pht('Query')));
+
+    $form_box = id(new PHUIObjectBoxView())
+      ->setHeaderText(pht('Token Query'))
+      ->setForm($form);
+
+    $table = new AphrontTableView($content);
+    $table->setHeaders(
+      array(
+        'Name',
+        'URI',
+        'PHID',
+        'Priority',
+        'Display Name',
+        'Display Type',
+        'Image URI',
+        'Priority Type',
+      ));
+
+    $result_box = id(new PHUIObjectBoxView())
+      ->setHeaderText(pht('Token Results (%s)', $this->class))
+      ->appendChild($table);
+
+    return $this->buildApplicationPage(
+      array(
+        $form_box,
+        $result_box,
+      ),
+      array(
+        'title' => pht('Typeahead Results'),
+      ));
+  }
+
+}
Index: src/applications/typeahead/datasource/PhabricatorTypeaheadCompositeDatasource.php
===================================================================
--- /dev/null
+++ src/applications/typeahead/datasource/PhabricatorTypeaheadCompositeDatasource.php
@@ -0,0 +1,49 @@
+<?php
+
+abstract class PhabricatorTypeaheadCompositeDatasource
+  extends PhabricatorTypeaheadDatasource {
+
+  abstract public function getComponentDatasources();
+
+  public function getDatasourceApplicationClass() {
+    return null;
+  }
+
+  public function loadResults() {
+    $results = array();
+    foreach ($this->getUsableDatasources() as $source) {
+      $source
+        ->setRawQuery($this->getRawQuery())
+        ->setQuery($this->getQuery())
+        ->setViewer($this->getViewer())
+        ->setLimit($this->getLimit());
+
+      $results[] = $source->loadResults();
+    }
+    return array_mergev($results);
+  }
+
+  private function getUsableDatasources() {
+    $sources = $this->getComponentDatasources();
+
+    $usable = array();
+    foreach ($sources as $source) {
+      $application_class = $source->getDatasourceApplicationClass();
+
+      if ($application_class) {
+        $result = id(new PhabricatorApplicationQuery())
+          ->setViewer($this->getViewer())
+          ->withClasses(array($application_class))
+          ->execute();
+        if (!$result) {
+          continue;
+        }
+      }
+
+      $usable[] = $source;
+    }
+
+    return $usable;
+  }
+
+}
Index: src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php
===================================================================
--- /dev/null
+++ src/applications/typeahead/datasource/PhabricatorTypeaheadDatasource.php
@@ -0,0 +1,50 @@
+<?php
+
+abstract class PhabricatorTypeaheadDatasource extends Phobject {
+
+  private $viewer;
+  private $query;
+  private $rawQuery;
+  private $limit;
+
+  public function setLimit($limit) {
+    $this->limit = $limit;
+    return $this;
+  }
+
+  public function getLimit() {
+    return $this->limit;
+  }
+
+  public function setViewer(PhabricatorUser $viewer) {
+    $this->viewer = $viewer;
+    return $this;
+  }
+
+  public function getViewer() {
+    return $this->viewer;
+  }
+
+  public function setRawQuery($raw_query) {
+    $this->rawQuery = $raw_query;
+    return $this;
+  }
+
+  public function getRawQuery() {
+    return $this->rawQuery;
+  }
+
+  public function setQuery($query) {
+    $this->query = $query;
+    return $this;
+  }
+
+  public function getQuery() {
+    return $this->query;
+  }
+
+  abstract public function getPlaceholderText();
+  abstract public function getDatasourceApplicationClass();
+  abstract public function loadResults();
+
+}
Index: src/applications/typeahead/datasource/PhabricatorTypeaheadMonogramDatasource.php
===================================================================
--- /dev/null
+++ src/applications/typeahead/datasource/PhabricatorTypeaheadMonogramDatasource.php
@@ -0,0 +1,43 @@
+<?php
+
+final class PhabricatorTypeaheadMonogramDatasource
+  extends PhabricatorTypeaheadDatasource {
+
+  public function getPlaceholderText() {
+    return pht('Type an object name...');
+  }
+
+  public function getDatasourceApplicationClass() {
+    return null;
+  }
+
+  public function loadResults() {
+    $viewer = $this->getViewer();
+    $raw_query = $this->getRawQuery();
+
+    $results = array();
+
+    $objects = id(new PhabricatorObjectQuery())
+      ->setViewer($viewer)
+      ->withNames(array($raw_query))
+      ->execute();
+    if ($objects) {
+      $handles = id(new PhabricatorHandleQuery())
+        ->setViewer($viewer)
+        ->withPHIDs(mpull($objects, 'getPHID'))
+        ->execute();
+      $handle = head($handles);
+      if ($handle) {
+        $results[] = id(new PhabricatorTypeaheadResult())
+          ->setName($handle->getFullName())
+          ->setDisplayType($handle->getTypeName())
+          ->setURI($handle->getURI())
+          ->setPHID($handle->getPHID())
+          ->setPriorityType('jump');
+      }
+    }
+
+    return $results;
+  }
+
+}
Index: src/applications/typeahead/datasource/PhabricatorTypeaheadRuntimeCompositeDatasource.php
===================================================================
--- /dev/null
+++ src/applications/typeahead/datasource/PhabricatorTypeaheadRuntimeCompositeDatasource.php
@@ -0,0 +1,21 @@
+<?php
+
+final class PhabricatorTypeaheadRuntimeCompositeDatasource
+  extends PhabricatorTypeaheadCompositeDatasource {
+
+  private $datasources = array();
+
+  public function getComponentDatasources() {
+    return $this->datasources;
+  }
+
+  public function getPlaceholderText() {
+    throw new Exception(pht('This source is not usable directly.'));
+  }
+
+  public function addDatasource(PhabricatorTypeaheadDatasource $source) {
+    $this->datasources[] = $source;
+    return $this;
+  }
+
+}