diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 5afb2b104f..a564ba0f3b 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -149,6 +149,7 @@ phutil_register_library_map(array(
     'ConduitAPI_diffusion_browsequery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_browsequery_Method.php',
     'ConduitAPI_diffusion_diffquery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_diffquery_Method.php',
     'ConduitAPI_diffusion_existsquery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_existsquery_Method.php',
+    'ConduitAPI_diffusion_expandshortcommitquery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_expandshortcommitquery_Method.php',
     'ConduitAPI_diffusion_filecontentquery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_filecontentquery_Method.php',
     'ConduitAPI_diffusion_findsymbols_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_findsymbols_Method.php',
     'ConduitAPI_diffusion_getcommits_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_getcommits_Method.php',
@@ -429,6 +430,8 @@ phutil_register_library_map(array(
     'DiffusionController' => 'applications/diffusion/controller/DiffusionController.php',
     'DiffusionDiffController' => 'applications/diffusion/controller/DiffusionDiffController.php',
     'DiffusionEmptyResultView' => 'applications/diffusion/view/DiffusionEmptyResultView.php',
+    'DiffusionExpandCommitQueryException' => 'applications/diffusion/exception/DiffusionExpandCommitQueryException.php',
+    'DiffusionExpandShortNameQuery' => 'applications/diffusion/query/expandshortname/DiffusionExpandShortNameQuery.php',
     'DiffusionExternalController' => 'applications/diffusion/controller/DiffusionExternalController.php',
     'DiffusionFileContent' => 'applications/diffusion/data/DiffusionFileContent.php',
     'DiffusionFileContentQuery' => 'applications/diffusion/query/filecontent/DiffusionFileContentQuery.php',
@@ -436,6 +439,7 @@ phutil_register_library_map(array(
     'DiffusionGitBranchTestCase' => 'applications/diffusion/data/__tests__/DiffusionGitBranchTestCase.php',
     'DiffusionGitCommitParentsQuery' => 'applications/diffusion/query/parents/DiffusionGitCommitParentsQuery.php',
     'DiffusionGitContainsQuery' => 'applications/diffusion/query/contains/DiffusionGitContainsQuery.php',
+    'DiffusionGitExpandShortNameQuery' => 'applications/diffusion/query/expandshortname/DiffusionGitExpandShortNameQuery.php',
     'DiffusionGitFileContentQuery' => 'applications/diffusion/query/filecontent/DiffusionGitFileContentQuery.php',
     'DiffusionGitHistoryQuery' => 'applications/diffusion/query/history/DiffusionGitHistoryQuery.php',
     'DiffusionGitMergedCommitsQuery' => 'applications/diffusion/query/mergedcommits/DiffusionGitMergedCommitsQuery.php',
@@ -454,6 +458,7 @@ phutil_register_library_map(array(
     'DiffusionLintSaveRunner' => 'applications/diffusion/DiffusionLintSaveRunner.php',
     'DiffusionMercurialCommitParentsQuery' => 'applications/diffusion/query/parents/DiffusionMercurialCommitParentsQuery.php',
     'DiffusionMercurialContainsQuery' => 'applications/diffusion/query/contains/DiffusionMercurialContainsQuery.php',
+    'DiffusionMercurialExpandShortNameQuery' => 'applications/diffusion/query/expandshortname/DiffusionMercurialExpandShortNameQuery.php',
     'DiffusionMercurialFileContentQuery' => 'applications/diffusion/query/filecontent/DiffusionMercurialFileContentQuery.php',
     'DiffusionMercurialHistoryQuery' => 'applications/diffusion/query/history/DiffusionMercurialHistoryQuery.php',
     'DiffusionMercurialMergedCommitsQuery' => 'applications/diffusion/query/mergedcommits/DiffusionMercurialMergedCommitsQuery.php',
@@ -1940,6 +1945,7 @@ phutil_register_library_map(array(
     'ConduitAPI_diffusion_browsequery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
     'ConduitAPI_diffusion_diffquery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
     'ConduitAPI_diffusion_existsquery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
+    'ConduitAPI_diffusion_expandshortcommitquery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
     'ConduitAPI_diffusion_filecontentquery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
     'ConduitAPI_diffusion_findsymbols_Method' => 'ConduitAPI_diffusion_Method',
     'ConduitAPI_diffusion_getcommits_Method' => 'ConduitAPI_diffusion_Method',
@@ -2210,11 +2216,14 @@ phutil_register_library_map(array(
     'DiffusionController' => 'PhabricatorController',
     'DiffusionDiffController' => 'DiffusionController',
     'DiffusionEmptyResultView' => 'DiffusionView',
+    'DiffusionExpandCommitQueryException' => 'Exception',
+    'DiffusionExpandShortNameQuery' => 'DiffusionQuery',
     'DiffusionExternalController' => 'DiffusionController',
     'DiffusionFileContentQuery' => 'DiffusionQuery',
     'DiffusionGitBranchTestCase' => 'PhabricatorTestCase',
     'DiffusionGitCommitParentsQuery' => 'DiffusionCommitParentsQuery',
     'DiffusionGitContainsQuery' => 'DiffusionContainsQuery',
+    'DiffusionGitExpandShortNameQuery' => 'DiffusionExpandShortNameQuery',
     'DiffusionGitFileContentQuery' => 'DiffusionFileContentQuery',
     'DiffusionGitHistoryQuery' => 'DiffusionHistoryQuery',
     'DiffusionGitMergedCommitsQuery' => 'DiffusionMergedCommitsQuery',
@@ -2232,6 +2241,7 @@ phutil_register_library_map(array(
     'DiffusionLintDetailsController' => 'DiffusionController',
     'DiffusionMercurialCommitParentsQuery' => 'DiffusionCommitParentsQuery',
     'DiffusionMercurialContainsQuery' => 'DiffusionContainsQuery',
+    'DiffusionMercurialExpandShortNameQuery' => 'DiffusionExpandShortNameQuery',
     'DiffusionMercurialFileContentQuery' => 'DiffusionFileContentQuery',
     'DiffusionMercurialHistoryQuery' => 'DiffusionHistoryQuery',
     'DiffusionMercurialMergedCommitsQuery' => 'DiffusionMergedCommitsQuery',
diff --git a/src/applications/differential/view/DifferentialChangesetListView.php b/src/applications/differential/view/DifferentialChangesetListView.php
index dcd080dfe8..e10fe8bf2f 100644
--- a/src/applications/differential/view/DifferentialChangesetListView.php
+++ b/src/applications/differential/view/DifferentialChangesetListView.php
@@ -263,6 +263,7 @@ final class DifferentialChangesetListView extends AphrontView {
       try {
         $meta['diffusionURI'] =
           (string)$repository->getDiffusionBrowseURIForPath(
+            $this->user,
             $changeset->getAbsoluteRepositoryPath($repository, $this->diff),
             idx($changeset->getMetadata(), 'line:first'),
             $this->getBranch());
diff --git a/src/applications/diffusion/DiffusionLintSaveRunner.php b/src/applications/diffusion/DiffusionLintSaveRunner.php
index 6d2f0b3b4e..39612a88f1 100644
--- a/src/applications/diffusion/DiffusionLintSaveRunner.php
+++ b/src/applications/diffusion/DiffusionLintSaveRunner.php
@@ -235,6 +235,8 @@ final class DiffusionLintSaveRunner {
     $futures = array();
     foreach ($this->blame as $path => $lines) {
       $drequest = DiffusionRequest::newFromDictionary(array(
+        'user' => PhabricatorUser::getOmnipotentUser(),
+        'initFromConduit' => false,
         'repository' => $repository,
         'branch' => $this->branch->getName(),
         'path' => $path,
diff --git a/src/applications/diffusion/conduit/ConduitAPI_diffusion_abstractquery_Method.php b/src/applications/diffusion/conduit/ConduitAPI_diffusion_abstractquery_Method.php
index 09727976c4..1da13b9b4c 100644
--- a/src/applications/diffusion/conduit/ConduitAPI_diffusion_abstractquery_Method.php
+++ b/src/applications/diffusion/conduit/ConduitAPI_diffusion_abstractquery_Method.php
@@ -17,6 +17,9 @@ abstract class ConduitAPI_diffusion_abstractquery_Method
   }
 
   private $diffusionRequest;
+  private $repository;
+  private $shouldCreateDiffusionRequest = true;
+
   protected function setDiffusionRequest(DiffusionRequest $request) {
     $this->diffusionRequest = $request;
     return $this;
@@ -25,10 +28,54 @@ abstract class ConduitAPI_diffusion_abstractquery_Method
     return $this->diffusionRequest;
   }
 
+  /**
+   * A wee bit of magic here. If @{method:shouldCreateDiffusionRequest}
+   * returns false, this function grabs a repository object based on the
+   * callsign directly. Otherwise, the repository was loaded when we created a
+   * @{class:DiffusionRequest}, so this function just pulls it out of the
+   * @{class:DiffusionRequest}.
+   *
+   * @return @{class:PhabricatorRepository} $repository
+   */
+  protected function getRepository(ConduitAPIRequest $request) {
+    if (!$this->repository) {
+      if ($this->shouldCreateDiffusionRequest()) {
+        $this->repository = $this->getDiffusionRequest()->getRepository();
+      } else {
+        $callsign = $request->getValue('callsign');
+        $repository = id(new PhabricatorRepository())->loadOneWhere(
+          'callsign = %s',
+          $callsign);
+        if (!$repository) {
+          throw new ConduitException('ERR-UNKNOWN-REPOSITORY');
+        }
+        $this->repository = $repository;
+      }
+    }
+    return $this->repository;
+  }
+
+  /**
+   * You should probably not mess with this unless your conduit method is
+   * involved with the creation / validation / etc. of
+   * @{class:DiffusionRequest}s. If you are dealing with
+   * @{class:DiffusionRequest}, setting this to false should help avoid
+   * infinite loops.
+   */
+  protected function setShouldCreateDiffusionRequest($should) {
+    $this->shouldCreateDiffusionRequest = $should;
+    return $this;
+  }
+  private function shouldCreateDiffusionRequest() {
+    return $this->shouldCreateDiffusionRequest;
+  }
+
   final public function defineErrorTypes() {
     return $this->defineCustomErrorTypes() +
       array(
-        'ERR-UNKNOWN-REPOSITORY-VCS' =>
+        'ERR-UNKNOWN-REPOSITORY' =>
+          pht('There is no repository with that callsign.'),
+        'ERR-UNKNOWN-VCS-TYPE' =>
           pht('Unknown repository VCS type.'),
         'ERR-UNSUPPORTED-VCS' =>
           pht('VCS is not supported for this method.'));
@@ -70,29 +117,39 @@ abstract class ConduitAPI_diffusion_abstractquery_Method
   }
 
   /**
-   * This method is final because each query will need to construct a
+   * This method is final because most queries will need to construct a
    * @{class:DiffusionRequest} and use it. Consolidating this codepath and
    * enforcing @{method:getDiffusionRequest} works when we need it is good.
    *
    * @{method:getResult} should be overridden by subclasses as necessary, e.g.
    * there is a common operation across all version control systems that
    * should occur after @{method:getResult}, like formatting a timestamp.
+   *
+   * In the rare cases where one does not want to create a
+   * @{class:DiffusionRequest} - suppose to avoid infinite loops in the
+   * creation of a @{class:DiffusionRequest} - make sure to call
+   *
+   *   $this->setShouldCreateDiffusionRequest(false);
+   *
+   * in the constructor of the pertinent Conduit method.
    */
   final protected function execute(ConduitAPIRequest $request) {
-    $drequest = DiffusionRequest::newFromDictionary(
-      array(
-        'callsign' => $request->getValue('callsign'),
-        'path' => $request->getValue('path'),
-        'commit' => $request->getValue('commit'),
-      ));
-    $this->setDiffusionRequest($drequest);
+    if ($this->shouldCreateDiffusionRequest()) {
+      $drequest = DiffusionRequest::newFromDictionary(
+        array(
+          'user' => $request->getUser(),
+          'callsign' => $request->getValue('callsign'),
+          'path' => $request->getValue('path'),
+          'commit' => $request->getValue('commit'),
+        ));
+      $this->setDiffusionRequest($drequest);
+    }
 
     return $this->getResult($request);
   }
 
   protected function getResult(ConduitAPIRequest $request) {
-    $drequest = $this->getDiffusionRequest();
-    $repository = $drequest->getRepository();
+    $repository = $this->getRepository($request);
     $result = null;
     switch ($repository->getVersionControlSystem()) {
       case PhabricatorRepositoryType::REPOSITORY_TYPE_GIT:
@@ -105,7 +162,7 @@ abstract class ConduitAPI_diffusion_abstractquery_Method
         $result = $this->getSVNResult($request);
         break;
       default:
-        throw new ConduitException('ERR-UNKNOWN-REPOSITORY-VCS');
+        throw new ConduitException('ERR-UNKNOWN-VCS-TYPE');
         break;
     }
     return $result;
diff --git a/src/applications/diffusion/conduit/ConduitAPI_diffusion_browsequery_Method.php b/src/applications/diffusion/conduit/ConduitAPI_diffusion_browsequery_Method.php
index 3163b25990..b1ebcf9c53 100644
--- a/src/applications/diffusion/conduit/ConduitAPI_diffusion_browsequery_Method.php
+++ b/src/applications/diffusion/conduit/ConduitAPI_diffusion_browsequery_Method.php
@@ -61,9 +61,10 @@ final class ConduitAPI_diffusion_browsequery_Method
 
     $readme_request = DiffusionRequest::newFromDictionary(
       array(
-        'repository'  => $drequest->getRepository(),
-        'commit'      => $drequest->getStableCommitName(),
-        'path'        => $readme->getFullPath(),
+        'user' => $request->getUser(),
+        'repository' => $drequest->getRepository(),
+        'commit' => $drequest->getStableCommitName(),
+        'path' => $readme->getFullPath(),
       ));
 
     $file_content = DiffusionFileContent::newFromConduit(
diff --git a/src/applications/diffusion/conduit/ConduitAPI_diffusion_expandshortcommitquery_Method.php b/src/applications/diffusion/conduit/ConduitAPI_diffusion_expandshortcommitquery_Method.php
new file mode 100644
index 0000000000..0a97f94247
--- /dev/null
+++ b/src/applications/diffusion/conduit/ConduitAPI_diffusion_expandshortcommitquery_Method.php
@@ -0,0 +1,70 @@
+<?php
+
+/**
+ * @group conduit
+ */
+final class ConduitAPI_diffusion_expandshortcommitquery_Method
+  extends ConduitAPI_diffusion_abstractquery_Method {
+
+  public function __construct() {
+    $this->setShouldCreateDiffusionRequest(false);
+  }
+
+  public function getMethodDescription() {
+    return
+      'Expands a short commit name to its full glory.';
+  }
+
+  public function defineReturnType() {
+    return 'array';
+  }
+
+  protected function defineCustomParamTypes() {
+    return array(
+      'commit' => 'required string',
+    );
+  }
+
+  protected function defineCustomErrorTypes() {
+    return array(
+      'ERR-MISSING-COMMIT' => pht(
+        'Bad commit.'),
+      'ERR-INVALID-COMMIT' => pht(
+        'Invalid object name.'),
+      'ERR-UNPARSEABLE-OUTPUT' => pht(
+        'Unparseable output from cat-file.')
+    );
+  }
+
+  protected function getGitResult(ConduitAPIRequest $request) {
+    return $this->getGitOrMercurialResult($request);
+  }
+  protected function getMercurialResult(ConduitAPIRequest $request) {
+    return $this->getGitOrMercurialResult($request);
+  }
+
+  private function getGitOrMercurialResult(ConduitAPIRequest $request) {
+    $repository = $this->getRepository($request);
+    $query = DiffusionExpandShortNameQuery::newFromRepository($repository);
+    $query->setCommit($request->getValue('commit'));
+    try {
+      $result = $query->expand();
+      return $result;
+    } catch (DiffusionExpandCommitQueryException $e) {
+      switch ($e->getStatusCode()) {
+        case DiffusionExpandCommitQueryException::CODE_INVALID:
+          throw id(new ConduitException('ERR-INVALID-COMMIT'))
+            ->setErrorDescription($e->getMessage());
+          break;
+        case DiffusionExpandCommitQueryException::CODE_MISSING:
+          throw id(new ConduitException('ERR-MISSING-COMMIT'))
+            ->setErrorDescription($e->getMessage());
+          break;
+        case DiffusionExpandCommitQueryException::CODE_UNPARSEABLE:
+          throw id(new ConduitException('ERR-UNPARSEABLE-OUTPUT'))
+            ->setErrorDescription($e->getMessage());
+         break;
+      }
+    }
+  }
+}
diff --git a/src/applications/diffusion/conduit/ConduitAPI_diffusion_getrecentcommitsbypath_Method.php b/src/applications/diffusion/conduit/ConduitAPI_diffusion_getrecentcommitsbypath_Method.php
index fa21056597..d6c3e95ab1 100644
--- a/src/applications/diffusion/conduit/ConduitAPI_diffusion_getrecentcommitsbypath_Method.php
+++ b/src/applications/diffusion/conduit/ConduitAPI_diffusion_getrecentcommitsbypath_Method.php
@@ -32,8 +32,9 @@ final class ConduitAPI_diffusion_getrecentcommitsbypath_Method
   protected function execute(ConduitAPIRequest $request) {
     $drequest = DiffusionRequest::newFromDictionary(
       array(
-        'callsign'  => $request->getValue('callsign'),
-        'path'      => $request->getValue('path'),
+        'user' => $request->getUser(),
+        'callsign' => $request->getValue('callsign'),
+        'path' => $request->getValue('path'),
       ));
 
     $limit = nonempty(
diff --git a/src/applications/diffusion/controller/DiffusionBrowseFileController.php b/src/applications/diffusion/controller/DiffusionBrowseFileController.php
index f43cf6a76c..c177f4918f 100644
--- a/src/applications/diffusion/controller/DiffusionBrowseFileController.php
+++ b/src/applications/diffusion/controller/DiffusionBrowseFileController.php
@@ -957,6 +957,7 @@ final class DiffusionBrowseFileController extends DiffusionController {
 
     $before_req = DiffusionRequest::newFromDictionary(
       array(
+        'user' => $this->getRequest()->getUser(),
         'repository' => $drequest->getRepository(),
         'commit'     => $commit,
       ));
diff --git a/src/applications/diffusion/controller/DiffusionCommitBranchesController.php b/src/applications/diffusion/controller/DiffusionCommitBranchesController.php
index 4b306f5b10..9453f9fe44 100644
--- a/src/applications/diffusion/controller/DiffusionCommitBranchesController.php
+++ b/src/applications/diffusion/controller/DiffusionCommitBranchesController.php
@@ -3,6 +3,7 @@
 final class DiffusionCommitBranchesController extends DiffusionController {
 
   public function willProcessRequest(array $data) {
+    $data['user'] = $this->getRequest()->getUser();
     $this->diffusionRequest = DiffusionRequest::newFromDictionary($data);
   }
 
diff --git a/src/applications/diffusion/controller/DiffusionCommitController.php b/src/applications/diffusion/controller/DiffusionCommitController.php
index 641690b627..24c8bc0d8c 100644
--- a/src/applications/diffusion/controller/DiffusionCommitController.php
+++ b/src/applications/diffusion/controller/DiffusionCommitController.php
@@ -10,6 +10,7 @@ final class DiffusionCommitController extends DiffusionController {
   public function willProcessRequest(array $data) {
     // This controller doesn't use blob/path stuff, just pass the dictionary
     // in directly instead of using the AphrontRequest parsing mechanism.
+    $data['user'] = $this->getRequest()->getUser();
     $drequest = DiffusionRequest::newFromDictionary($data);
     $this->diffusionRequest = $drequest;
   }
diff --git a/src/applications/diffusion/controller/DiffusionCommitEditController.php b/src/applications/diffusion/controller/DiffusionCommitEditController.php
index d893dabd91..8345a6eedd 100644
--- a/src/applications/diffusion/controller/DiffusionCommitEditController.php
+++ b/src/applications/diffusion/controller/DiffusionCommitEditController.php
@@ -3,6 +3,7 @@
 final class DiffusionCommitEditController extends DiffusionController {
 
   public function willProcessRequest(array $data) {
+    $data['user'] = $this->getRequest()->getUser();
     $this->diffusionRequest = DiffusionRequest::newFromDictionary($data);
   }
 
diff --git a/src/applications/diffusion/controller/DiffusionCommitTagsController.php b/src/applications/diffusion/controller/DiffusionCommitTagsController.php
index 9ac8077dfd..cac70f616e 100644
--- a/src/applications/diffusion/controller/DiffusionCommitTagsController.php
+++ b/src/applications/diffusion/controller/DiffusionCommitTagsController.php
@@ -3,6 +3,7 @@
 final class DiffusionCommitTagsController extends DiffusionController {
 
   public function willProcessRequest(array $data) {
+    $data['user'] = $this->getRequest()->getUser();
     $this->diffusionRequest = DiffusionRequest::newFromDictionary($data);
   }
 
diff --git a/src/applications/diffusion/controller/DiffusionLintController.php b/src/applications/diffusion/controller/DiffusionLintController.php
index 22fb166ec8..604041c45a 100644
--- a/src/applications/diffusion/controller/DiffusionLintController.php
+++ b/src/applications/diffusion/controller/DiffusionLintController.php
@@ -40,6 +40,7 @@ final class DiffusionLintController extends DiffusionController {
       $drequests = array();
       foreach ($branches as $id => $branch) {
         $drequests[$id] = DiffusionRequest::newFromDictionary(array(
+          'user' => $user,
           'repository' => $repositories[$branch->getRepositoryID()],
           'branch' => $branch->getName(),
         ));
diff --git a/src/applications/diffusion/controller/DiffusionPathCompleteController.php b/src/applications/diffusion/controller/DiffusionPathCompleteController.php
index fbba21b953..b9dd4f117c 100644
--- a/src/applications/diffusion/controller/DiffusionPathCompleteController.php
+++ b/src/applications/diffusion/controller/DiffusionPathCompleteController.php
@@ -27,8 +27,9 @@ final class DiffusionPathCompleteController extends DiffusionController {
 
     $drequest = DiffusionRequest::newFromDictionary(
       array(
-        'repository'  => $repository,
-        'path'        => $query_dir,
+        'user' => $request->getUser(),
+        'repository' => $repository,
+        'path' => $query_dir,
       ));
     $this->setDiffusionRequest($drequest);
 
diff --git a/src/applications/diffusion/controller/DiffusionPathValidateController.php b/src/applications/diffusion/controller/DiffusionPathValidateController.php
index 9a2c2625c3..980b1bcb2f 100644
--- a/src/applications/diffusion/controller/DiffusionPathValidateController.php
+++ b/src/applications/diffusion/controller/DiffusionPathValidateController.php
@@ -22,8 +22,9 @@ final class DiffusionPathValidateController extends DiffusionController {
 
     $drequest = DiffusionRequest::newFromDictionary(
       array(
-        'repository'  => $repository,
-        'path'        => $path,
+        'user' => $request->getUser(),
+        'repository' => $repository,
+        'path' => $path,
       ));
     $this->setDiffusionRequest($drequest);
 
diff --git a/src/applications/diffusion/exception/DiffusionExpandCommitQueryException.php b/src/applications/diffusion/exception/DiffusionExpandCommitQueryException.php
new file mode 100644
index 0000000000..fab33a6f98
--- /dev/null
+++ b/src/applications/diffusion/exception/DiffusionExpandCommitQueryException.php
@@ -0,0 +1,21 @@
+<?php
+
+final class DiffusionExpandCommitQueryException extends Exception {
+  const CODE_UNPARSEABLE = 'unparseable';
+  const CODE_MISSING = 'missing';
+  const CODE_INVALID = 'invalid';
+
+  private $statusCode;
+  public function getStatusCode() {
+    return $this->statusCode;
+  }
+
+  public function __construct($status_code /* ... */) {
+    $args = func_get_args();
+    $this->statusCode = $args[0];
+
+    $args = array_slice($args, 1);
+    call_user_func_array(array('parent', '__construct'), $args);
+  }
+
+}
diff --git a/src/applications/diffusion/query/DiffusionQuery.php b/src/applications/diffusion/query/DiffusionQuery.php
index 7846730ef3..40292db927 100644
--- a/src/applications/diffusion/query/DiffusionQuery.php
+++ b/src/applications/diffusion/query/DiffusionQuery.php
@@ -14,6 +14,16 @@ abstract class DiffusionQuery extends PhabricatorQuery {
 
     $repository = $request->getRepository();
 
+    $obj = self::initQueryObject($base_class, $repository);
+    $obj->request = $request;
+
+    return $obj;
+  }
+
+  final protected static function initQueryObject(
+    $base_class,
+    PhabricatorRepository $repository) {
+
     $map = array(
       PhabricatorRepositoryType::REPOSITORY_TYPE_GIT        => 'Git',
       PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL  => 'Mercurial',
@@ -27,8 +37,6 @@ abstract class DiffusionQuery extends PhabricatorQuery {
 
     $class = str_replace('Diffusion', 'Diffusion'.$name, $base_class);
     $obj = new $class();
-    $obj->request = $request;
-
     return $obj;
   }
 
diff --git a/src/applications/diffusion/query/expandshortname/DiffusionExpandShortNameQuery.php b/src/applications/diffusion/query/expandshortname/DiffusionExpandShortNameQuery.php
new file mode 100644
index 0000000000..1413d6450f
--- /dev/null
+++ b/src/applications/diffusion/query/expandshortname/DiffusionExpandShortNameQuery.php
@@ -0,0 +1,42 @@
+<?php
+
+abstract class DiffusionExpandShortNameQuery extends DiffusionQuery {
+
+  private $commit;
+  private $commitType = 'commit';
+  private $tagContent;
+  private $repository;
+
+  public function setCommit($commit) {
+    $this->commit = $commit;
+  }
+  public function getCommit() {
+    return $this->commit;
+  }
+
+  public function setRepository(PhabricatorRepository $repository) {
+    $this->repository = $repository;
+    return $this;
+  }
+  public function getRepository() {
+    return $this->repository;
+  }
+
+  final public static function newFromRepository(
+    PhabricatorRepository $repository) {
+
+    $obj = parent::initQueryObject(__CLASS__, $repository);
+    $obj->setRepository($repository);
+    return $obj;
+  }
+
+  final public function expand() {
+    $this->executeQuery();
+
+    return array(
+      'commit' => $this->commit,
+      'commitType' => $this->commitType,
+      'tagContent' => $this->tagContent);
+  }
+
+}
diff --git a/src/applications/diffusion/query/expandshortname/DiffusionGitExpandShortNameQuery.php b/src/applications/diffusion/query/expandshortname/DiffusionGitExpandShortNameQuery.php
new file mode 100644
index 0000000000..96694e613f
--- /dev/null
+++ b/src/applications/diffusion/query/expandshortname/DiffusionGitExpandShortNameQuery.php
@@ -0,0 +1,52 @@
+<?php
+
+final class DiffusionGitExpandShortNameQuery
+extends DiffusionExpandShortNameQuery {
+
+  protected function executeQuery() {
+    $repository = $this->getRepository();
+    $commit = $this->getCommit();
+
+    $future = $repository->getLocalCommandFuture(
+      'cat-file --batch');
+    $future->write($commit);
+    list($stdout) = $future->resolvex();
+
+    list($hash, $type) = explode(' ', $stdout);
+    if ($type == 'missing') {
+      throw new DiffusionExpandCommitQueryException(
+        DiffusionExpandCommitQueryException::CODE_MISSING,
+        "Bad commit '{$this->commit}'.");
+    }
+
+    switch ($type) {
+      case 'tag':
+        $this->commitType = 'tag';
+
+        $matches = null;
+        $ok = preg_match(
+          '/^object ([a-f0-9]+)$.*?\n\n(.*)$/sm',
+          $stdout,
+          $matches);
+        if (!$ok) {
+          throw new DiffusionExpandCommitQueryException(
+            DiffusionExpandCommitQueryException::CODE_UNPARSEABLE,
+            "Unparseable output from cat-file: {$stdout}");
+        }
+
+        $hash = $matches[1];
+        $this->tagContent = trim($matches[2]);
+        break;
+      case 'commit':
+        break;
+      default:
+        throw new DiffusionExpandCommitQueryException(
+          DiffusionExpandCommitQueryException::CODE_INVALID,
+          "The reference '{$this->commit}' does not name a valid ".
+          'commit or a tag in this repository.');
+        break;
+    }
+
+    $this->commit = $hash;
+  }
+}
diff --git a/src/applications/diffusion/query/expandshortname/DiffusionMercurialExpandShortNameQuery.php b/src/applications/diffusion/query/expandshortname/DiffusionMercurialExpandShortNameQuery.php
new file mode 100644
index 0000000000..6d1d5ed404
--- /dev/null
+++ b/src/applications/diffusion/query/expandshortname/DiffusionMercurialExpandShortNameQuery.php
@@ -0,0 +1,23 @@
+<?php
+
+final class DiffusionMercurialExpandShortNameQuery
+extends DiffusionExpandShortNameQuery {
+
+  protected function executeQuery() {
+    $repository = $this->getRepository();
+    $commit = $this->getCommit();
+
+    list($full_hash) = $repository->execxLocalCommand(
+      'log --template=%s --rev %s',
+      '{node}',
+      $commit);
+
+    $full_hash = explode("\n", trim($full_hash));
+
+    // TODO: Show "multiple matching commits" if count is larger than 1. For
+    // now, pick the first one.
+
+    $this->commit = head($full_hash);
+  }
+
+}
diff --git a/src/applications/diffusion/request/DiffusionGitRequest.php b/src/applications/diffusion/request/DiffusionGitRequest.php
index 8cc99b600d..268bc29fe2 100644
--- a/src/applications/diffusion/request/DiffusionGitRequest.php
+++ b/src/applications/diffusion/request/DiffusionGitRequest.php
@@ -10,54 +10,11 @@ final class DiffusionGitRequest extends DiffusionRequest {
   }
 
   protected function didInitialize() {
-    $repository = $this->getRepository();
-
-    $this->validateWorkingCopy($repository->getLocalPath());
-
     if (!$this->commit) {
       return;
     }
 
-    // Expand short commit names and verify
-
-    $future = $repository->getLocalCommandFuture(
-      'cat-file --batch');
-    $future->write($this->commit);
-    list($stdout) = $future->resolvex();
-
-    list($hash, $type) = explode(' ', $stdout);
-    if ($type == 'missing') {
-      throw new Exception("Bad commit '{$this->commit}'.");
-    }
-
-    switch ($type) {
-      case 'tag':
-        $this->commitType = 'tag';
-
-        $matches = null;
-        $ok = preg_match(
-          '/^object ([a-f0-9]+)$.*?\n\n(.*)$/sm',
-          $stdout,
-          $matches);
-        if (!$ok) {
-          throw new Exception(
-            "Unparseable output from cat-file: {$stdout}");
-        }
-
-        $hash = $matches[1];
-        $this->tagContent = trim($matches[2]);
-        break;
-      case 'commit':
-        break;
-      default:
-        throw new AphrontUsageException(
-          "Invalid Object Name",
-          "The reference '{$this->commit}' does not name a valid ".
-          "commit or a tag in this repository.");
-        break;
-    }
-
-    $this->commit = $hash;
+    $this->expandCommitName();
   }
 
   public function getBranch() {
diff --git a/src/applications/diffusion/request/DiffusionMercurialRequest.php b/src/applications/diffusion/request/DiffusionMercurialRequest.php
index 79a828ee3f..3f630401e7 100644
--- a/src/applications/diffusion/request/DiffusionMercurialRequest.php
+++ b/src/applications/diffusion/request/DiffusionMercurialRequest.php
@@ -10,10 +10,6 @@ final class DiffusionMercurialRequest extends DiffusionRequest {
   }
 
   protected function didInitialize() {
-    $repository = $this->getRepository();
-
-    $this->validateWorkingCopy($repository->getLocalPath());
-
     // Expand abbreviated hashes to full hashes so "/rXnnnn" (i.e., fewer than
     // 40 characters) works correctly.
     if (!$this->commit) {
@@ -24,21 +20,8 @@ final class DiffusionMercurialRequest extends DiffusionRequest {
       return;
     }
 
-    list($full_hash) = $this->repository->execxLocalCommand(
-      'log --template=%s --rev %s',
-      '{node}',
-      $this->commit);
-
-    $full_hash = explode("\n", trim($full_hash));
-
-    // TODO: Show "multiple matching commits" if count is larger than 1. For
-    // now, pick the first one.
-
-    $this->commit = head($full_hash);
-
-
-    return;
-  }
+    $this->expandCommitName();
+ }
 
   public function getBranch() {
     if ($this->branch) {
diff --git a/src/applications/diffusion/request/DiffusionRequest.php b/src/applications/diffusion/request/DiffusionRequest.php
index e7f5005fe0..632ab6965b 100644
--- a/src/applications/diffusion/request/DiffusionRequest.php
+++ b/src/applications/diffusion/request/DiffusionRequest.php
@@ -17,9 +17,9 @@ abstract class DiffusionRequest {
   protected $line;
   protected $symbolicCommit;
   protected $commit;
-  protected $branch;
   protected $commitType = 'commit';
   protected $tagContent;
+  protected $branch;
   protected $lint;
 
   protected $repository;
@@ -28,6 +28,9 @@ abstract class DiffusionRequest {
   protected $stableCommitName;
   protected $arcanistProjects;
 
+  private $initFromConduit = true;
+  private $user;
+
   abstract protected function getSupportsBranches();
   abstract protected function didInitialize();
 
@@ -91,6 +94,7 @@ abstract class DiffusionRequest {
     $use_branches = $object->getSupportsBranches();
     $parsed = self::parseRequestBlob(idx($data, 'dblob'), $use_branches);
 
+    $object->setUser($request->getUser());
     $object->initializeFromDictionary($parsed);
     $object->lint = $request->getStr('lint');
     return $object;
@@ -167,18 +171,39 @@ abstract class DiffusionRequest {
    * @task new
    */
   final private function initializeFromDictionary(array $data) {
-    $this->path           = idx($data, 'path');
-    $this->symbolicCommit = idx($data, 'commit');
-    $this->commit         = idx($data, 'commit');
-    $this->line           = idx($data, 'line');
+    $this->path            = idx($data, 'path');
+    $this->symbolicCommit  = idx($data, 'commit');
+    $this->commit          = idx($data, 'commit');
+    $this->line            = idx($data, 'line');
+    $this->initFromConduit = idx($data, 'initFromConduit', true);
 
     if ($this->getSupportsBranches()) {
       $this->branch = idx($data, 'branch');
     }
 
+    if (!$this->getUser()) {
+      $user = idx($data, 'user');
+      if (!$user) {
+        throw new Exception(
+          'You must provide a PhabricatorUser in the dictionary!');
+      }
+      $this->setUser($user);
+    }
+
     $this->didInitialize();
   }
 
+  final protected function shouldInitFromConduit() {
+    return $this->initFromConduit;
+  }
+
+  final public function setUser(PhabricatorUser $user) {
+    $this->user = $user;
+    return $this;
+  }
+  final public function getUser() {
+    return $this->user;
+  }
 
   public function getRepository() {
     return $this->repository;
@@ -580,4 +605,27 @@ abstract class DiffusionRequest {
       "Guide' in the documentation for help setting up repositories.");
   }
 
+  final protected function expandCommitName() {
+    if ($this->shouldInitFromConduit()) {
+      $commit_data = DiffusionQuery::callConduitWithDiffusionRequest(
+        $this->getUser(),
+        $this,
+        'diffusion.expandshortcommitquery',
+        array(
+          'commit' => $this->commit
+        ));
+    } else {
+      $repository = $this->getRepository();
+      $this->validateWorkingCopy($repository->getLocalPath());
+      $query = DiffusionExpandShortNameQuery::newFromRepository(
+        $repository);
+      $query->setCommit($this->commit);
+      $commit_data = $query->expand();
+    }
+
+    $this->commit = $commit_data['commit'];
+    $this->commitType = $commit_data['commitType'];
+    $this->tagContent = $commit_data['tagContent'];
+  }
+
 }
diff --git a/src/applications/herald/adapter/HeraldCommitAdapter.php b/src/applications/herald/adapter/HeraldCommitAdapter.php
index 543221eb63..a73eeb875e 100644
--- a/src/applications/herald/adapter/HeraldCommitAdapter.php
+++ b/src/applications/herald/adapter/HeraldCommitAdapter.php
@@ -106,6 +106,7 @@ final class HeraldCommitAdapter extends HeraldObjectAdapter {
   private function loadCommitDiff() {
     $drequest = DiffusionRequest::newFromDictionary(
       array(
+        'user' => PhabricatorUser::getOmnipotentUser(),
         'repository' => $this->repository,
         'commit' => $this->commit->getCommitIdentifier(),
       ));
diff --git a/src/applications/owners/storage/PhabricatorOwnersPackage.php b/src/applications/owners/storage/PhabricatorOwnersPackage.php
index f625aa6355..f3e644cb6f 100644
--- a/src/applications/owners/storage/PhabricatorOwnersPackage.php
+++ b/src/applications/owners/storage/PhabricatorOwnersPackage.php
@@ -309,6 +309,7 @@ final class PhabricatorOwnersPackage extends PhabricatorOwnersDAO
           // build query to validate path
           $drequest = DiffusionRequest::newFromDictionary(
             array(
+              'user' => $this->getActor(),
               'repository'  => $repository,
               'path'        => $path,
             ));
diff --git a/src/applications/releeph/commitfinder/ReleephCommitFinder.php b/src/applications/releeph/commitfinder/ReleephCommitFinder.php
index 3212944419..71e4b2c301 100644
--- a/src/applications/releeph/commitfinder/ReleephCommitFinder.php
+++ b/src/applications/releeph/commitfinder/ReleephCommitFinder.php
@@ -3,6 +3,15 @@
 final class ReleephCommitFinder {
 
   private $releephProject;
+  private $user;
+
+  public function setUser(PhabricatorUser $user) {
+    $this->user = $user;
+    return $this;
+  }
+  public function getUser() {
+    return $this->user;
+  }
 
   public function setReleephProject(ReleephProject $rp) {
     $this->releephProject = $rp;
@@ -55,6 +64,7 @@ final class ReleephCommitFinder {
     }
 
     try {
+      $dr_data['user'] = $this->getUser();
       $dr = DiffusionRequest::newFromDictionary($dr_data);
     } catch (Exception $ex) {
       $message = "No commit matches {$partial_string}: ".$ex->getMessage();
diff --git a/src/applications/releeph/conduit/ConduitAPI_releeph_request_Method.php b/src/applications/releeph/conduit/ConduitAPI_releeph_request_Method.php
index e0275e476d..ec7f924519 100644
--- a/src/applications/releeph/conduit/ConduitAPI_releeph_request_Method.php
+++ b/src/applications/releeph/conduit/ConduitAPI_releeph_request_Method.php
@@ -43,6 +43,7 @@ final class ConduitAPI_releeph_request_Method
     $requested_commits = array();
     $things = $request->getValue('things');
     $finder = id(new ReleephCommitFinder())
+      ->setUser($user)
       ->setReleephProject($releeph_project);
     foreach ($things as $thing) {
       try {
diff --git a/src/applications/releeph/controller/branch/ReleephBranchCreateController.php b/src/applications/releeph/controller/branch/ReleephBranchCreateController.php
index 01c9923379..ecee3d481a 100644
--- a/src/applications/releeph/controller/branch/ReleephBranchCreateController.php
+++ b/src/applications/releeph/controller/branch/ReleephBranchCreateController.php
@@ -41,6 +41,7 @@ final class ReleephBranchCreateController extends ReleephController {
       } else {
         try {
           $finder = id(new ReleephCommitFinder())
+            ->setUser($request->getUser())
             ->setReleephProject($releeph_project);
           $cut_commit = $finder->fromPartial($cut_point);
         } catch (Exception $e) {
diff --git a/src/applications/releeph/controller/request/ReleephRequestEditController.php b/src/applications/releeph/controller/request/ReleephRequestEditController.php
index a458aab3f9..95775d2bcd 100644
--- a/src/applications/releeph/controller/request/ReleephRequestEditController.php
+++ b/src/applications/releeph/controller/request/ReleephRequestEditController.php
@@ -71,6 +71,7 @@ final class ReleephRequestEditController extends ReleephController {
         } else {
           $pr_commit = null;
           $finder = id(new ReleephCommitFinder())
+            ->setUser($user)
             ->setReleephProject($releeph_project);
           try {
             $pr_commit = $finder->fromPartial($request_identifier);
@@ -186,7 +187,7 @@ final class ReleephRequestEditController extends ReleephController {
     }
 
     $form = id(new AphrontFormView())
-      ->setUser($request->getUser());
+      ->setUser($user);
 
     if ($is_edit) {
       $form
diff --git a/src/applications/releeph/differential/DifferentialReleephRequestFieldSpecification.php b/src/applications/releeph/differential/DifferentialReleephRequestFieldSpecification.php
index e568646797..982c166a14 100644
--- a/src/applications/releeph/differential/DifferentialReleephRequestFieldSpecification.php
+++ b/src/applications/releeph/differential/DifferentialReleephRequestFieldSpecification.php
@@ -327,8 +327,9 @@ final class DifferentialReleephRequestFieldSpecification
       case PhabricatorRepositoryType::REPOSITORY_TYPE_SVN:
         $change_query = DiffusionPathChangeQuery::newFromDiffusionRequest(
           DiffusionRequest::newFromDictionary(array(
-            'repository'  => $repo,
-            'commit'      => $commit->getCommitIdentifier(),
+            'user' => $this->getUser(),
+            'repository' => $repo,
+            'commit' => $commit->getCommitIdentifier(),
           )));
         $path_changes = $change_query->loadChanges();
         $commit_paths = mpull($path_changes, 'getPath');
diff --git a/src/applications/releeph/view/branch/ReleephBranchBoxView.php b/src/applications/releeph/view/branch/ReleephBranchBoxView.php
index 7a5acde4c3..8161c4c42a 100644
--- a/src/applications/releeph/view/branch/ReleephBranchBoxView.php
+++ b/src/applications/releeph/view/branch/ReleephBranchBoxView.php
@@ -167,6 +167,7 @@ final class ReleephBranchBoxView extends AphrontView {
         "Diffusion \xE2\x86\x97");
     } else {
       $diffusion_request = DiffusionRequest::newFromDictionary(array(
+        'user' => $this->getUser(),
         'repository' => $repo,
       ));
       $diffusion_branch_uri = $diffusion_request->generateURI(array(
diff --git a/src/applications/repository/storage/PhabricatorRepository.php b/src/applications/repository/storage/PhabricatorRepository.php
index 94cb122fb1..bd4d85f675 100644
--- a/src/applications/repository/storage/PhabricatorRepository.php
+++ b/src/applications/repository/storage/PhabricatorRepository.php
@@ -69,14 +69,18 @@ final class PhabricatorRepository extends PhabricatorRepositoryDAO
     return $this;
   }
 
-  public function getDiffusionBrowseURIForPath($path,
-                                               $line = null,
-                                               $branch = null) {
+  public function getDiffusionBrowseURIForPath(
+    PhabricatorUser $user,
+    $path,
+    $line = null,
+    $branch = null) {
+
     $drequest = DiffusionRequest::newFromDictionary(
       array(
+        'user' => $user,
         'repository' => $this,
-        'path'       => $path,
-        'branch'     => $branch,
+        'path' => $path,
+        'branch' => $branch,
       ));
 
     return $drequest->generateURI(
diff --git a/src/applications/repository/storage/PhabricatorRepositorySymbol.php b/src/applications/repository/storage/PhabricatorRepositorySymbol.php
index e74a27fe08..fb24bb215a 100644
--- a/src/applications/repository/storage/PhabricatorRepositorySymbol.php
+++ b/src/applications/repository/storage/PhabricatorRepositorySymbol.php
@@ -39,7 +39,8 @@ final class PhabricatorRepositorySymbol extends PhabricatorRepositoryDAO {
 
     $request = DiffusionRequest::newFromDictionary(
       array(
-        'repository'  => $this->getRepository(),
+        'user' => PhabricatorUser::getOmnipotentUser(),
+        'repository' => $this->getRepository(),
       ));
     return $request->generateURI(
       array(
diff --git a/src/applications/repository/worker/PhabricatorRepositoryCommitHeraldWorker.php b/src/applications/repository/worker/PhabricatorRepositoryCommitHeraldWorker.php
index 5baa23443d..64803aed7a 100644
--- a/src/applications/repository/worker/PhabricatorRepositoryCommitHeraldWorker.php
+++ b/src/applications/repository/worker/PhabricatorRepositoryCommitHeraldWorker.php
@@ -363,8 +363,10 @@ final class PhabricatorRepositoryCommitHeraldWorker
 
     $drequest = DiffusionRequest::newFromDictionary(
       array(
-        'repository'  => $repository,
-        'commit'      => $commit->getCommitIdentifier(),
+        'user' => PhabricatorUser::getOmnipotentUser(),
+        'initFromConduit' => false,
+        'repository' => $repository,
+        'commit' => $commit->getCommitIdentifier(),
       ));
 
     $raw_query = DiffusionRawDiffQuery::newFromDiffusionRequest($drequest);
diff --git a/src/applications/repository/worker/commitchangeparser/PhabricatorOwnersPackagePathValidator.php b/src/applications/repository/worker/commitchangeparser/PhabricatorOwnersPackagePathValidator.php
index e3f5d590ba..3a62f07656 100644
--- a/src/applications/repository/worker/commitchangeparser/PhabricatorOwnersPackagePathValidator.php
+++ b/src/applications/repository/worker/commitchangeparser/PhabricatorOwnersPackagePathValidator.php
@@ -85,8 +85,10 @@ final class PhabricatorOwnersPackagePathValidator {
     $repository =
       id(new PhabricatorRepository())->load($commit->getRepositoryID());
     $data = array(
-      'repository'=>$repository,
-      'commit'=>$commit->getCommitIdentifier()
+      'user' => PhabricatorUser::getOmnipotentUser(),
+      'initFromConduit' => false,
+      'repository' => $repository,
+      'commit' => $commit->getCommitIdentifier()
     );
     $drequest = DiffusionRequest::newFromDictionary($data);
     $change_query =
diff --git a/src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php b/src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php
index dd48746d87..b8faffbaf6 100644
--- a/src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php
+++ b/src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php
@@ -230,6 +230,8 @@ abstract class PhabricatorRepositoryCommitMessageParserWorker
     $actor_phid) {
 
     $drequest = DiffusionRequest::newFromDictionary(array(
+      'user' => PhabricatorUser::getOmnipotentUser(),
+      'initFromConduit' => false,
       'repository' => $this->repository,
       'commit' => $this->commit->getCommitIdentifier(),
     ));
@@ -333,6 +335,8 @@ abstract class PhabricatorRepositoryCommitMessageParserWorker
           return $vs_diff;
         }
         $drequest = DiffusionRequest::newFromDictionary(array(
+          'user' => PhabricatorUser::getOmnipotentUser(),
+          'initFromConduit' => false,
           'repository' => $this->repository,
           'commit' => $this->commit->getCommitIdentifier(),
           'path' => $path,