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
@@ -831,6 +831,7 @@
     'DiffusionQueryCommitsConduitAPIMethod' => 'applications/diffusion/conduit/DiffusionQueryCommitsConduitAPIMethod.php',
     'DiffusionQueryConduitAPIMethod' => 'applications/diffusion/conduit/DiffusionQueryConduitAPIMethod.php',
     'DiffusionQueryPathsConduitAPIMethod' => 'applications/diffusion/conduit/DiffusionQueryPathsConduitAPIMethod.php',
+    'DiffusionQuickSearchEngineExtension' => 'applications/diffusion/engineextension/DiffusionQuickSearchEngineExtension.php',
     'DiffusionRawDiffQuery' => 'applications/diffusion/query/rawdiff/DiffusionRawDiffQuery.php',
     'DiffusionRawDiffQueryConduitAPIMethod' => 'applications/diffusion/conduit/DiffusionRawDiffQueryConduitAPIMethod.php',
     'DiffusionReadmeView' => 'applications/diffusion/view/DiffusionReadmeView.php',
@@ -3202,6 +3203,7 @@
     'PhabricatorMetronomicTriggerClock' => 'infrastructure/daemon/workers/clock/PhabricatorMetronomicTriggerClock.php',
     'PhabricatorModularTransaction' => 'applications/transactions/storage/PhabricatorModularTransaction.php',
     'PhabricatorModularTransactionType' => 'applications/transactions/storage/PhabricatorModularTransactionType.php',
+    'PhabricatorMonogramQuickSearchEngineExtension' => 'applications/typeahead/engineextension/PhabricatorMonogramQuickSearchEngineExtension.php',
     'PhabricatorMonospacedFontSetting' => 'applications/settings/setting/PhabricatorMonospacedFontSetting.php',
     'PhabricatorMonospacedTextareasSetting' => 'applications/settings/setting/PhabricatorMonospacedTextareasSetting.php',
     'PhabricatorMotivatorProfileMenuItem' => 'applications/search/menuitem/PhabricatorMotivatorProfileMenuItem.php',
@@ -3525,6 +3527,7 @@
     'PhabricatorPeopleProfileTasksController' => 'applications/people/controller/PhabricatorPeopleProfileTasksController.php',
     'PhabricatorPeopleProfileViewController' => 'applications/people/controller/PhabricatorPeopleProfileViewController.php',
     'PhabricatorPeopleQuery' => 'applications/people/query/PhabricatorPeopleQuery.php',
+    'PhabricatorPeopleQuickSearchEngineExtension' => 'applications/people/engineextension/PhabricatorPeopleQuickSearchEngineExtension.php',
     'PhabricatorPeopleRenameController' => 'applications/people/controller/PhabricatorPeopleRenameController.php',
     'PhabricatorPeopleRevisionsProfileMenuItem' => 'applications/people/menuitem/PhabricatorPeopleRevisionsProfileMenuItem.php',
     'PhabricatorPeopleSearchEngine' => 'applications/people/query/PhabricatorPeopleSearchEngine.php',
@@ -3785,6 +3788,9 @@
     'PhabricatorQueryOrderItem' => 'infrastructure/query/order/PhabricatorQueryOrderItem.php',
     'PhabricatorQueryOrderTestCase' => 'infrastructure/query/order/__tests__/PhabricatorQueryOrderTestCase.php',
     'PhabricatorQueryOrderVector' => 'infrastructure/query/order/PhabricatorQueryOrderVector.php',
+    'PhabricatorQuickSearchApplicationEngineExtension' => 'applications/meta/engineextension/PhabricatorQuickSearchApplicationEngineExtension.php',
+    'PhabricatorQuickSearchEngine' => 'applications/search/engine/PhabricatorQuickSearchEngine.php',
+    'PhabricatorQuickSearchEngineExtension' => 'applications/search/engineextension/PhabricatorQuickSearchEngineExtension.php',
     'PhabricatorRateLimitRequestExceptionHandler' => 'aphront/handler/PhabricatorRateLimitRequestExceptionHandler.php',
     'PhabricatorRecaptchaConfigOptions' => 'applications/config/option/PhabricatorRecaptchaConfigOptions.php',
     'PhabricatorRedirectController' => 'applications/base/controller/PhabricatorRedirectController.php',
@@ -4817,6 +4823,7 @@
     'ProjectDefaultViewCapability' => 'applications/project/capability/ProjectDefaultViewCapability.php',
     'ProjectEditConduitAPIMethod' => 'applications/project/conduit/ProjectEditConduitAPIMethod.php',
     'ProjectQueryConduitAPIMethod' => 'applications/project/conduit/ProjectQueryConduitAPIMethod.php',
+    'ProjectQuickSearchEngineExtension' => 'applications/project/engineextension/ProjectQuickSearchEngineExtension.php',
     'ProjectRemarkupRule' => 'applications/project/remarkup/ProjectRemarkupRule.php',
     'ProjectRemarkupRuleTestCase' => 'applications/project/remarkup/__tests__/ProjectRemarkupRuleTestCase.php',
     'ProjectReplyHandler' => 'applications/project/mail/ProjectReplyHandler.php',
@@ -5880,6 +5887,7 @@
     'DiffusionQueryCommitsConduitAPIMethod' => 'DiffusionConduitAPIMethod',
     'DiffusionQueryConduitAPIMethod' => 'DiffusionConduitAPIMethod',
     'DiffusionQueryPathsConduitAPIMethod' => 'DiffusionQueryConduitAPIMethod',
+    'DiffusionQuickSearchEngineExtension' => 'PhabricatorQuickSearchEngineExtension',
     'DiffusionRawDiffQuery' => 'DiffusionFileFutureQuery',
     'DiffusionRawDiffQueryConduitAPIMethod' => 'DiffusionQueryConduitAPIMethod',
     'DiffusionReadmeView' => 'DiffusionView',
@@ -8612,6 +8620,7 @@
     'PhabricatorMetronomicTriggerClock' => 'PhabricatorTriggerClock',
     'PhabricatorModularTransaction' => 'PhabricatorApplicationTransaction',
     'PhabricatorModularTransactionType' => 'Phobject',
+    'PhabricatorMonogramQuickSearchEngineExtension' => 'PhabricatorQuickSearchEngineExtension',
     'PhabricatorMonospacedFontSetting' => 'PhabricatorStringSetting',
     'PhabricatorMonospacedTextareasSetting' => 'PhabricatorSelectSetting',
     'PhabricatorMotivatorProfileMenuItem' => 'PhabricatorProfileMenuItem',
@@ -9004,6 +9013,7 @@
     'PhabricatorPeopleProfileTasksController' => 'PhabricatorPeopleProfileController',
     'PhabricatorPeopleProfileViewController' => 'PhabricatorPeopleProfileController',
     'PhabricatorPeopleQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
+    'PhabricatorPeopleQuickSearchEngineExtension' => 'PhabricatorQuickSearchEngineExtension',
     'PhabricatorPeopleRenameController' => 'PhabricatorPeopleController',
     'PhabricatorPeopleRevisionsProfileMenuItem' => 'PhabricatorProfileMenuItem',
     'PhabricatorPeopleSearchEngine' => 'PhabricatorApplicationSearchEngine',
@@ -9319,6 +9329,9 @@
       'Phobject',
       'Iterator',
     ),
+    'PhabricatorQuickSearchApplicationEngineExtension' => 'PhabricatorQuickSearchEngineExtension',
+    'PhabricatorQuickSearchEngine' => 'Phobject',
+    'PhabricatorQuickSearchEngineExtension' => 'Phobject',
     'PhabricatorRateLimitRequestExceptionHandler' => 'PhabricatorRequestExceptionHandler',
     'PhabricatorRecaptchaConfigOptions' => 'PhabricatorApplicationConfigOptions',
     'PhabricatorRedirectController' => 'PhabricatorController',
@@ -10605,6 +10618,7 @@
     'ProjectDefaultViewCapability' => 'PhabricatorPolicyCapability',
     'ProjectEditConduitAPIMethod' => 'PhabricatorEditEngineAPIMethod',
     'ProjectQueryConduitAPIMethod' => 'ProjectConduitAPIMethod',
+    'ProjectQuickSearchEngineExtension' => 'PhabricatorQuickSearchEngineExtension',
     'ProjectRemarkupRule' => 'PhabricatorObjectRemarkupRule',
     'ProjectRemarkupRuleTestCase' => 'PhabricatorTestCase',
     'ProjectReplyHandler' => 'PhabricatorApplicationTransactionReplyHandler',
diff --git a/src/applications/diffusion/engineextension/DiffusionQuickSearchEngineExtension.php b/src/applications/diffusion/engineextension/DiffusionQuickSearchEngineExtension.php
new file mode 100644
--- /dev/null
+++ b/src/applications/diffusion/engineextension/DiffusionQuickSearchEngineExtension.php
@@ -0,0 +1,12 @@
+<?php
+
+final class DiffusionQuickSearchEngineExtension
+  extends PhabricatorQuickSearchEngineExtension {
+
+  public function newQuickSearchDatasources() {
+    return array(
+      new DiffusionRepositoryDatasource(),
+      new DiffusionSymbolDatasource(),
+    );
+  }
+}
diff --git a/src/applications/meta/engineextension/PhabricatorQuickSearchApplicationEngineExtension.php b/src/applications/meta/engineextension/PhabricatorQuickSearchApplicationEngineExtension.php
new file mode 100644
--- /dev/null
+++ b/src/applications/meta/engineextension/PhabricatorQuickSearchApplicationEngineExtension.php
@@ -0,0 +1,11 @@
+<?php
+
+final class PhabricatorQuickSearchApplicationEngineExtension
+  extends PhabricatorQuickSearchEngineExtension {
+
+  public function newQuickSearchDatasources() {
+    return array(
+      new PhabricatorApplicationDatasource(),
+    );
+  }
+}
diff --git a/src/applications/people/engineextension/PhabricatorPeopleQuickSearchEngineExtension.php b/src/applications/people/engineextension/PhabricatorPeopleQuickSearchEngineExtension.php
new file mode 100644
--- /dev/null
+++ b/src/applications/people/engineextension/PhabricatorPeopleQuickSearchEngineExtension.php
@@ -0,0 +1,11 @@
+<?php
+
+final class PhabricatorPeopleQuickSearchEngineExtension
+  extends PhabricatorQuickSearchEngineExtension {
+
+  public function newQuickSearchDatasources() {
+    return array(
+      new PhabricatorPeopleDatasource(),
+    );
+  }
+}
diff --git a/src/applications/project/engineextension/ProjectQuickSearchEngineExtension.php b/src/applications/project/engineextension/ProjectQuickSearchEngineExtension.php
new file mode 100644
--- /dev/null
+++ b/src/applications/project/engineextension/ProjectQuickSearchEngineExtension.php
@@ -0,0 +1,11 @@
+<?php
+
+final class ProjectQuickSearchEngineExtension
+  extends PhabricatorQuickSearchEngineExtension {
+
+  public function newQuickSearchDatasources() {
+    return array(
+      new PhabricatorProjectDatasource(),
+    );
+  }
+}
diff --git a/src/applications/search/engine/PhabricatorQuickSearchEngine.php b/src/applications/search/engine/PhabricatorQuickSearchEngine.php
new file mode 100644
--- /dev/null
+++ b/src/applications/search/engine/PhabricatorQuickSearchEngine.php
@@ -0,0 +1,8 @@
+<?php
+
+final class PhabricatorQuickSearchEngine extends Phobject {
+
+  public function getAllDatasources() {
+    return PhabricatorQuickSearchEngineExtension::getAllDatasources();
+  }
+}
diff --git a/src/applications/search/engineextension/PhabricatorQuickSearchEngineExtension.php b/src/applications/search/engineextension/PhabricatorQuickSearchEngineExtension.php
new file mode 100644
--- /dev/null
+++ b/src/applications/search/engineextension/PhabricatorQuickSearchEngineExtension.php
@@ -0,0 +1,18 @@
+<?php
+
+abstract class PhabricatorQuickSearchEngineExtension extends Phobject {
+
+  abstract public function newQuickSearchDatasources();
+
+  final public static function getAllDatasources() {
+    $extensions = id(new PhutilClassMapQuery())
+      ->setAncestorClass(__CLASS__)
+      ->execute();
+
+    $datasources = array();
+    foreach ($extensions as $extension) {
+      $datasources[] = $extension->newQuickSearchDatasources();
+    }
+    return array_mergev($datasources);
+  }
+}
diff --git a/src/applications/search/typeahead/PhabricatorSearchDatasource.php b/src/applications/search/typeahead/PhabricatorSearchDatasource.php
--- a/src/applications/search/typeahead/PhabricatorSearchDatasource.php
+++ b/src/applications/search/typeahead/PhabricatorSearchDatasource.php
@@ -16,14 +16,8 @@
   }
 
   public function getComponentDatasources() {
-    $sources = array(
-      new PhabricatorPeopleDatasource(),
-      new PhabricatorProjectDatasource(),
-      new PhabricatorApplicationDatasource(),
-      new PhabricatorTypeaheadMonogramDatasource(),
-      new DiffusionRepositoryDatasource(),
-      new DiffusionSymbolDatasource(),
-    );
+    $sources = id(new PhabricatorQuickSearchEngine())
+      ->getAllDatasources();
 
     // These results are always rendered in the full browse display mode, so
     // set the browse flag on all component sources.
diff --git a/src/applications/typeahead/engineextension/PhabricatorMonogramQuickSearchEngineExtension.php b/src/applications/typeahead/engineextension/PhabricatorMonogramQuickSearchEngineExtension.php
new file mode 100644
--- /dev/null
+++ b/src/applications/typeahead/engineextension/PhabricatorMonogramQuickSearchEngineExtension.php
@@ -0,0 +1,11 @@
+<?php
+
+final class PhabricatorMonogramQuickSearchEngineExtension
+  extends PhabricatorQuickSearchEngineExtension {
+
+  public function newQuickSearchDatasources() {
+    return array(
+      new PhabricatorTypeaheadMonogramDatasource(),
+    );
+  }
+}