Index: src/__phutil_library_map__.php
===================================================================
--- src/__phutil_library_map__.php
+++ src/__phutil_library_map__.php
@@ -151,7 +151,6 @@
     'ConduitAPI_diffusion_createcomment_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_createcomment_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',
@@ -164,8 +163,8 @@
     'ConduitAPI_diffusion_rawdiffquery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_rawdiffquery_Method.php',
     'ConduitAPI_diffusion_readmequery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_readmequery_Method.php',
     'ConduitAPI_diffusion_refsquery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_refsquery_Method.php',
+    'ConduitAPI_diffusion_resolverefs_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_resolverefs_Method.php',
     'ConduitAPI_diffusion_searchquery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_searchquery_Method.php',
-    'ConduitAPI_diffusion_stablecommitnamequery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_stablecommitnamequery_Method.php',
     'ConduitAPI_diffusion_tagsquery_Method' => 'applications/diffusion/conduit/ConduitAPI_diffusion_tagsquery_Method.php',
     'ConduitAPI_feed_Method' => 'applications/feed/conduit/ConduitAPI_feed_Method.php',
     'ConduitAPI_feed_publish_Method' => 'applications/feed/conduit/ConduitAPI_feed_publish_Method.php',
@@ -472,20 +471,16 @@
     'DiffusionDiffController' => 'applications/diffusion/controller/DiffusionDiffController.php',
     'DiffusionDoorkeeperCommitFeedStoryPublisher' => 'applications/diffusion/doorkeeper/DiffusionDoorkeeperCommitFeedStoryPublisher.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',
     'DiffusionGitBranch' => 'applications/diffusion/data/DiffusionGitBranch.php',
     'DiffusionGitBranchTestCase' => 'applications/diffusion/data/__tests__/DiffusionGitBranchTestCase.php',
     'DiffusionGitCommitParentsQuery' => 'applications/diffusion/query/parents/DiffusionGitCommitParentsQuery.php',
-    'DiffusionGitExpandShortNameQuery' => 'applications/diffusion/query/expandshortname/DiffusionGitExpandShortNameQuery.php',
     'DiffusionGitFileContentQuery' => 'applications/diffusion/query/filecontent/DiffusionGitFileContentQuery.php',
     'DiffusionGitRawDiffQuery' => 'applications/diffusion/query/rawdiff/DiffusionGitRawDiffQuery.php',
     'DiffusionGitRequest' => 'applications/diffusion/request/DiffusionGitRequest.php',
     'DiffusionGitResponse' => 'applications/diffusion/response/DiffusionGitResponse.php',
-    'DiffusionGitStableCommitNameQuery' => 'applications/diffusion/query/stablecommitname/DiffusionGitStableCommitNameQuery.php',
     'DiffusionHistoryController' => 'applications/diffusion/controller/DiffusionHistoryController.php',
     'DiffusionHistoryTableView' => 'applications/diffusion/view/DiffusionHistoryTableView.php',
     'DiffusionHovercardEventListener' => 'applications/diffusion/events/DiffusionHovercardEventListener.php',
@@ -498,12 +493,11 @@
     'DiffusionLowLevelGitRefQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelGitRefQuery.php',
     'DiffusionLowLevelMercurialBranchesQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelMercurialBranchesQuery.php',
     'DiffusionLowLevelQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelQuery.php',
+    'DiffusionLowLevelResolveRefsQuery' => 'applications/diffusion/query/lowlevel/DiffusionLowLevelResolveRefsQuery.php',
     'DiffusionMercurialCommitParentsQuery' => 'applications/diffusion/query/parents/DiffusionMercurialCommitParentsQuery.php',
-    'DiffusionMercurialExpandShortNameQuery' => 'applications/diffusion/query/expandshortname/DiffusionMercurialExpandShortNameQuery.php',
     'DiffusionMercurialFileContentQuery' => 'applications/diffusion/query/filecontent/DiffusionMercurialFileContentQuery.php',
     'DiffusionMercurialRawDiffQuery' => 'applications/diffusion/query/rawdiff/DiffusionMercurialRawDiffQuery.php',
     'DiffusionMercurialRequest' => 'applications/diffusion/request/DiffusionMercurialRequest.php',
-    'DiffusionMercurialStableCommitNameQuery' => 'applications/diffusion/query/stablecommitname/DiffusionMercurialStableCommitNameQuery.php',
     'DiffusionPathChange' => 'applications/diffusion/data/DiffusionPathChange.php',
     'DiffusionPathChangeQuery' => 'applications/diffusion/query/pathchange/DiffusionPathChangeQuery.php',
     'DiffusionPathCompleteController' => 'applications/diffusion/controller/DiffusionPathCompleteController.php',
@@ -542,12 +536,10 @@
     'DiffusionSSHWorkflow' => 'applications/diffusion/ssh/DiffusionSSHWorkflow.php',
     'DiffusionSetPasswordPanel' => 'applications/diffusion/panel/DiffusionSetPasswordPanel.php',
     'DiffusionSetupException' => 'applications/diffusion/exception/DiffusionSetupException.php',
-    'DiffusionStableCommitNameQuery' => 'applications/diffusion/query/stablecommitname/DiffusionStableCommitNameQuery.php',
     'DiffusionSvnCommitParentsQuery' => 'applications/diffusion/query/parents/DiffusionSvnCommitParentsQuery.php',
     'DiffusionSvnFileContentQuery' => 'applications/diffusion/query/filecontent/DiffusionSvnFileContentQuery.php',
     'DiffusionSvnRawDiffQuery' => 'applications/diffusion/query/rawdiff/DiffusionSvnRawDiffQuery.php',
     'DiffusionSvnRequest' => 'applications/diffusion/request/DiffusionSvnRequest.php',
-    'DiffusionSvnStableCommitNameQuery' => 'applications/diffusion/query/stablecommitname/DiffusionSvnStableCommitNameQuery.php',
     'DiffusionSymbolController' => 'applications/diffusion/controller/DiffusionSymbolController.php',
     'DiffusionSymbolQuery' => 'applications/diffusion/query/DiffusionSymbolQuery.php',
     'DiffusionTagListController' => 'applications/diffusion/controller/DiffusionTagListController.php',
@@ -2366,7 +2358,6 @@
     'ConduitAPI_diffusion_createcomment_Method' => 'ConduitAPI_diffusion_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',
@@ -2379,8 +2370,8 @@
     'ConduitAPI_diffusion_rawdiffquery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
     'ConduitAPI_diffusion_readmequery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
     'ConduitAPI_diffusion_refsquery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
+    'ConduitAPI_diffusion_resolverefs_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
     'ConduitAPI_diffusion_searchquery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
-    'ConduitAPI_diffusion_stablecommitnamequery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
     'ConduitAPI_diffusion_tagsquery_Method' => 'ConduitAPI_diffusion_abstractquery_Method',
     'ConduitAPI_feed_Method' => 'ConduitAPIMethod',
     'ConduitAPI_feed_publish_Method' => 'ConduitAPI_feed_Method',
@@ -2681,18 +2672,14 @@
     'DiffusionDiffController' => 'DiffusionController',
     'DiffusionDoorkeeperCommitFeedStoryPublisher' => 'DoorkeeperFeedStoryPublisher',
     'DiffusionEmptyResultView' => 'DiffusionView',
-    'DiffusionExpandCommitQueryException' => 'Exception',
-    'DiffusionExpandShortNameQuery' => 'DiffusionQuery',
     'DiffusionExternalController' => 'DiffusionController',
     'DiffusionFileContentQuery' => 'DiffusionQuery',
     'DiffusionGitBranchTestCase' => 'PhabricatorTestCase',
     'DiffusionGitCommitParentsQuery' => 'DiffusionCommitParentsQuery',
-    'DiffusionGitExpandShortNameQuery' => 'DiffusionExpandShortNameQuery',
     'DiffusionGitFileContentQuery' => 'DiffusionFileContentQuery',
     'DiffusionGitRawDiffQuery' => 'DiffusionRawDiffQuery',
     'DiffusionGitRequest' => 'DiffusionRequest',
     'DiffusionGitResponse' => 'AphrontResponse',
-    'DiffusionGitStableCommitNameQuery' => 'DiffusionStableCommitNameQuery',
     'DiffusionHistoryController' => 'DiffusionController',
     'DiffusionHistoryTableView' => 'DiffusionView',
     'DiffusionHovercardEventListener' => 'PhabricatorEventListener',
@@ -2704,12 +2691,11 @@
     'DiffusionLowLevelGitRefQuery' => 'DiffusionLowLevelQuery',
     'DiffusionLowLevelMercurialBranchesQuery' => 'DiffusionLowLevelQuery',
     'DiffusionLowLevelQuery' => 'Phobject',
+    'DiffusionLowLevelResolveRefsQuery' => 'DiffusionLowLevelQuery',
     'DiffusionMercurialCommitParentsQuery' => 'DiffusionCommitParentsQuery',
-    'DiffusionMercurialExpandShortNameQuery' => 'DiffusionExpandShortNameQuery',
     'DiffusionMercurialFileContentQuery' => 'DiffusionFileContentQuery',
     'DiffusionMercurialRawDiffQuery' => 'DiffusionRawDiffQuery',
     'DiffusionMercurialRequest' => 'DiffusionRequest',
-    'DiffusionMercurialStableCommitNameQuery' => 'DiffusionStableCommitNameQuery',
     'DiffusionPathCompleteController' => 'DiffusionController',
     'DiffusionPathQueryTestCase' => 'PhabricatorTestCase',
     'DiffusionPathValidateController' => 'DiffusionController',
@@ -2743,12 +2729,10 @@
     'DiffusionSSHWorkflow' => 'PhabricatorSSHWorkflow',
     'DiffusionSetPasswordPanel' => 'PhabricatorSettingsPanel',
     'DiffusionSetupException' => 'AphrontUsageException',
-    'DiffusionStableCommitNameQuery' => 'DiffusionQuery',
     'DiffusionSvnCommitParentsQuery' => 'DiffusionCommitParentsQuery',
     'DiffusionSvnFileContentQuery' => 'DiffusionFileContentQuery',
     'DiffusionSvnRawDiffQuery' => 'DiffusionRawDiffQuery',
     'DiffusionSvnRequest' => 'DiffusionRequest',
-    'DiffusionSvnStableCommitNameQuery' => 'DiffusionStableCommitNameQuery',
     'DiffusionSymbolController' => 'DiffusionController',
     'DiffusionSymbolQuery' => 'PhabricatorOffsetPagedQuery',
     'DiffusionTagListController' => 'DiffusionController',
Index: src/applications/diffusion/conduit/ConduitAPI_diffusion_browsequery_Method.php
===================================================================
--- src/applications/diffusion/conduit/ConduitAPI_diffusion_browsequery_Method.php
+++ src/applications/diffusion/conduit/ConduitAPI_diffusion_browsequery_Method.php
@@ -198,7 +198,7 @@
 
     list($entire_manifest) = $repository->execxLocalCommand(
       'manifest --rev %s',
-      $commit);
+      hgsprintf('%s', $commit));
     $entire_manifest = explode("\n", $entire_manifest);
 
     $results = array();
Index: src/applications/diffusion/conduit/ConduitAPI_diffusion_expandshortcommitquery_Method.php
===================================================================
--- src/applications/diffusion/conduit/ConduitAPI_diffusion_expandshortcommitquery_Method.php
+++ /dev/null
@@ -1,70 +0,0 @@
-<?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;
-      }
-    }
-  }
-}
Index: src/applications/diffusion/conduit/ConduitAPI_diffusion_resolverefs_Method.php
===================================================================
--- /dev/null
+++ src/applications/diffusion/conduit/ConduitAPI_diffusion_resolverefs_Method.php
@@ -0,0 +1,29 @@
+<?php
+
+final class ConduitAPI_diffusion_resolverefs_Method
+  extends ConduitAPI_diffusion_abstractquery_Method {
+
+  public function getMethodDescription() {
+    return pht('Resolve references into stable, canonical identifiers.');
+  }
+
+  public function defineReturnType() {
+    return 'dict<string, list<dict<string, wild>>>';
+  }
+
+  protected function defineCustomParamTypes() {
+    return array(
+      'refs' => 'required list<string>',
+    );
+  }
+
+  protected function getResult(ConduitAPIRequest $request) {
+    $refs = $request->getValue('refs');
+
+    return id(new DiffusionLowLevelResolveRefsQuery())
+      ->setRepository($this->getDiffusionRequest()->getRepository())
+      ->withRefs($refs)
+      ->execute();
+  }
+
+}
Index: src/applications/diffusion/conduit/ConduitAPI_diffusion_stablecommitnamequery_Method.php
===================================================================
--- src/applications/diffusion/conduit/ConduitAPI_diffusion_stablecommitnamequery_Method.php
+++ /dev/null
@@ -1,35 +0,0 @@
-<?php
-
-/**
- * @group conduit
- */
-final class ConduitAPI_diffusion_stablecommitnamequery_Method
-  extends ConduitAPI_diffusion_abstractquery_Method {
-
-  public function __construct() {
-    $this->setShouldCreateDiffusionRequest(false);
-  }
-
-  public function getMethodDescription() {
-    return
-      'Identifies the latest commit in a repository. Repositories with '.
-      'branch support must specify which branch to look at.';
-  }
-
-  public function defineReturnType() {
-    return 'string';
-  }
-
-  protected function defineCustomParamTypes() {
-    return array(
-      'branch' => 'required string',
-    );
-  }
-
-  protected function getResult(ConduitAPIRequest $request) {
-    $repository = $this->getRepository($request);
-    $query = DiffusionStableCommitNameQuery::newFromRepository($repository);
-    $query->setBranch($request->getValue('branch'));
-    return $query->load();
-  }
-}
Index: src/applications/diffusion/exception/DiffusionExpandCommitQueryException.php
===================================================================
--- src/applications/diffusion/exception/DiffusionExpandCommitQueryException.php
+++ /dev/null
@@ -1,21 +0,0 @@
-<?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);
-  }
-
-}
Index: src/applications/diffusion/query/expandshortname/DiffusionExpandShortNameQuery.php
===================================================================
--- src/applications/diffusion/query/expandshortname/DiffusionExpandShortNameQuery.php
+++ /dev/null
@@ -1,51 +0,0 @@
-<?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 $this->repository;
-  }
-
-  protected function setCommitType($type) {
-    $this->commitType = $type;
-    return $this;
-  }
-  protected function setTagContent($content) {
-    $this->tagContent = $content;
-    return $this;
-  }
-
-  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);
-  }
-
-}
Index: src/applications/diffusion/query/expandshortname/DiffusionGitExpandShortNameQuery.php
===================================================================
--- src/applications/diffusion/query/expandshortname/DiffusionGitExpandShortNameQuery.php
+++ /dev/null
@@ -1,52 +0,0 @@
-<?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 '{$commit}'.");
-    }
-
-    switch ($type) {
-      case 'tag':
-        $this->setCommitType('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];
-        $this->setTagContent(trim($matches[2]));
-        break;
-      case 'commit':
-        break;
-      default:
-        throw new DiffusionExpandCommitQueryException(
-          DiffusionExpandCommitQueryException::CODE_INVALID,
-          "The reference '{$commit}' does not name a valid ".
-          'commit or a tag in this repository.');
-        break;
-    }
-
-    $this->setCommit($hash);
-  }
-}
Index: src/applications/diffusion/query/expandshortname/DiffusionMercurialExpandShortNameQuery.php
===================================================================
--- src/applications/diffusion/query/expandshortname/DiffusionMercurialExpandShortNameQuery.php
+++ /dev/null
@@ -1,23 +0,0 @@
-<?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.
-
-    $this->setCommit(head($full_hash));
-  }
-
-}
Index: src/applications/diffusion/query/lowlevel/DiffusionLowLevelQuery.php
===================================================================
--- src/applications/diffusion/query/lowlevel/DiffusionLowLevelQuery.php
+++ src/applications/diffusion/query/lowlevel/DiffusionLowLevelQuery.php
@@ -16,6 +16,10 @@
   }
 
   public function execute() {
+    if (!$this->getRepository()) {
+      throw new Exception("Call setRepository() before execute()!");
+    }
+
     return $this->executeQuery();
   }
 
Index: src/applications/diffusion/query/lowlevel/DiffusionLowLevelResolveRefsQuery.php
===================================================================
--- /dev/null
+++ src/applications/diffusion/query/lowlevel/DiffusionLowLevelResolveRefsQuery.php
@@ -0,0 +1,225 @@
+<?php
+
+/**
+ * Resolves references (like short commit names, branch names, tag names, etc.)
+ * into canonical, stable commit identifiers. This query works for all
+ * repository types.
+ */
+final class DiffusionLowLevelResolveRefsQuery
+  extends DiffusionLowLevelQuery {
+
+  private $refs;
+
+  public function withRefs(array $refs) {
+    $this->refs = $refs;
+    return $this;
+  }
+
+  public function executeQuery() {
+    if (!$this->refs) {
+      return array();
+    }
+
+    switch ($this->getRepository()->getVersionControlSystem()) {
+      case PhabricatorRepositoryType::REPOSITORY_TYPE_GIT:
+        $result = $this->resolveGitRefs();
+        break;
+      case PhabricatorRepositoryType::REPOSITORY_TYPE_MERCURIAL:
+        $result = $this->resolveMercurialRefs();
+        break;
+      case PhabricatorRepositoryType::REPOSITORY_TYPE_SVN:
+        $result = $this->resolveSubversionRefs();
+        break;
+      default:
+        throw new Exception("Unsupported repository type!");
+    }
+
+    return $result;
+  }
+
+  private function resolveGitRefs() {
+    $repository = $this->getRepository();
+
+    $future = $repository->getLocalCommandFuture('cat-file --batch-check');
+    $future->write(implode("\n", $this->refs));
+    list($stdout) = $future->resolvex();
+
+    $lines = explode("\n", rtrim($stdout, "\n"));
+    if (count($lines) !== count($this->refs)) {
+      throw new Exception("Unexpected line count from `git cat-file`!");
+    }
+
+    $hits = array();
+    $tags = array();
+
+    $lines = array_combine($this->refs, $lines);
+    foreach ($lines as $ref => $line) {
+      $parts = explode(' ', $line);
+      if (count($parts) < 2) {
+        throw new Exception("Failed to parse `git cat-file` output: {$line}");
+      }
+      list($identifier, $type) = $parts;
+
+      if ($type == 'missing') {
+        // This is either an ambiguous reference which resolves to several
+        // objects, or an invalid reference. For now, always treat it as
+        // invalid. It would be nice to resolve all possibilities for
+        // ambiguous references at some point, although the strategy for doing
+        // so isn't clear to me.
+        continue;
+      }
+
+      switch ($type) {
+        case 'commit':
+          break;
+        case 'tag':
+          $tags[] = $identifier;
+          break;
+        default:
+          throw new Exception(
+            "Unexpected object type from `git cat-file`: {$line}");
+      }
+
+      $hits[] = array(
+        'ref' => $ref,
+        'type' => $type,
+        'identifier' => $identifier,
+      );
+    }
+
+    $tag_map = array();
+    if ($tags) {
+      // If some of the refs were tags, just load every tag in order to figure
+      // out which commits they map to. This might be somewhat inefficient in
+      // repositories with a huge number of tags.
+      $tag_refs = id(new DiffusionLowLevelGitRefQuery())
+        ->setRepository($repository)
+        ->withIsTag(true)
+        ->executeQuery();
+      foreach ($tag_refs as $tag_ref) {
+        $tag_map[$tag_ref->getShortName()] = $tag_ref->getCommitIdentifier();
+      }
+    }
+
+    $results = array();
+    foreach ($hits as $hit) {
+      $type = $hit['type'];
+      $ref = $hit['ref'];
+
+      $alternate = null;
+      if ($type == 'tag') {
+        $alternate = $identifier;
+        $identifier = idx($tag_map, $ref);
+        if (!$identifier) {
+          throw new Exception("Failed to look up tag '{$ref}'!");
+        }
+      }
+
+      $result = array(
+        'type' => $type,
+        'identifier' => $identifier,
+      );
+
+      if ($alternate !== null) {
+        $result['alternate'] = $alternate;
+      }
+
+      $results[$ref][] = $result;
+    }
+
+    return $results;
+  }
+
+  private function resolveMercurialRefs() {
+    $repository = $this->getRepository();
+
+    $futures = array();
+    foreach ($this->refs as $ref) {
+      // TODO: There was a note about `--rev 'a b'` not working for branches
+      // with spaces in their names in older code, but I suspect this was
+      // misidentified and resulted from the branch name being interpeted as
+      // a revset. Use hgsprintf() to avoid that. If this doesn't break for a
+      // bit, remove this comment. Otherwise, consider `-b %s --limit 1`.
+
+      $futures[$ref] = $repository->getLocalCommandFuture(
+        'log --template=%s --rev %s',
+        '{node}',
+        hgsprintf('%s', $ref));
+    }
+
+    $results = array();
+    foreach (Futures($futures) as $ref => $future) {
+      try {
+        list($stdout) = $future->resolvex();
+      } catch (CommandException $ex) {
+        if (preg_match('/ambiguous identifier/', $ex->getStdErr())) {
+          // This indicates that the ref ambiguously matched several things.
+          // Eventually, it would be nice to return all of them, but it is
+          // unclear how to best do that. For now, treat it as a miss instead.
+          continue;
+        }
+        throw $ex;
+      }
+
+      // It doesn't look like we can figure out the type (commit/branch/rev)
+      // from this output very easily. For now, just call everything a commit.
+      $type = 'commit';
+
+      $results[$ref][] = array(
+        'type' => $type,
+        'identifier' => trim($stdout),
+      );
+    }
+
+    return $results;
+  }
+
+  private function resolveSubversionRefs() {
+    $repository = $this->getRepository();
+
+    $max_commit = id(new PhabricatorRepositoryCommit())
+      ->loadOneWhere(
+        'repositoryID = %d ORDER BY epoch DESC, id DESC LIMIT 1',
+        $repository->getID());
+    if (!$max_commit) {
+      // This repository is empty or hasn't parsed yet, so none of the refs are
+      // going to resolve.
+      return array();
+    }
+
+    $max_commit_id = (int)$max_commit->getCommitIdentifier();
+
+    $results = array();
+    foreach ($this->refs as $ref) {
+      if ($ref == 'HEAD') {
+        // Resolve "HEAD" to mean "the most recent commit".
+        $results[$ref][] = array(
+          'type' => 'commit',
+          'identifier' => $max_commit_id,
+        );
+        continue;
+      }
+
+      if (!preg_match('/^\d+$/', $ref)) {
+        // This ref is non-numeric, so it doesn't resolve to anything.
+        continue;
+      }
+
+      // Resolve other commits if we can deduce their existence.
+
+      // TODO: When we import only part of a repository, we won't necessarily
+      // have all of the smaller commits. Should we fail to resolve them here
+      // for repositories with a subpath? It might let us simplify other things
+      // elsewhere.
+      if ((int)$ref <= $max_commit_id) {
+        $results[$ref][] = array(
+          'type' => 'commit',
+          'identifier' => (int)$ref,
+        );
+      }
+    }
+
+    return $results;
+  }
+
+}
Index: src/applications/diffusion/query/stablecommitname/DiffusionGitStableCommitNameQuery.php
===================================================================
--- src/applications/diffusion/query/stablecommitname/DiffusionGitStableCommitNameQuery.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-final class DiffusionGitStableCommitNameQuery
-extends DiffusionStableCommitNameQuery {
-
-  protected function executeQuery() {
-    $repository = $this->getRepository();
-    $branch = $this->getBranch();
-
-    if ($repository->isWorkingCopyBare()) {
-      list($stdout) = $repository->execxLocalCommand(
-        'rev-parse --verify %s',
-        $branch);
-    } else {
-      list($stdout) = $repository->execxLocalCommand(
-        'rev-parse --verify %s/%s',
-        DiffusionBranchInformation::DEFAULT_GIT_REMOTE,
-        $branch);
-    }
-
-    $commit = trim($stdout);
-    return substr($commit, 0, 16);
-  }
-}
Index: src/applications/diffusion/query/stablecommitname/DiffusionMercurialStableCommitNameQuery.php
===================================================================
--- src/applications/diffusion/query/stablecommitname/DiffusionMercurialStableCommitNameQuery.php
+++ /dev/null
@@ -1,30 +0,0 @@
-<?php
-
-final class DiffusionMercurialStableCommitNameQuery
-extends DiffusionStableCommitNameQuery {
-
-  protected function executeQuery() {
-    $repository = $this->getRepository();
-
-    // NOTE: For branches with spaces in their name like "a b", this
-    // does not work properly:
-    //
-    //   $ hg log --rev 'a b'
-    //
-    // We can use revsets instead:
-    //
-    //   $ hg log --rev branch('a b')
-    //
-    // ...but they require a somewhat newer version of Mercurial. Instead,
-    // use "-b" flag with limit 1 for greatest compatibility across
-    // versions.
-
-    list($stable_commit_name) = $repository->execxLocalCommand(
-      'log --template=%s -b %s --limit 1',
-      '{node}',
-      $this->getBranch());
-
-    return $stable_commit_name;
-  }
-
-}
Index: src/applications/diffusion/query/stablecommitname/DiffusionStableCommitNameQuery.php
===================================================================
--- src/applications/diffusion/query/stablecommitname/DiffusionStableCommitNameQuery.php
+++ /dev/null
@@ -1,35 +0,0 @@
-<?php
-
-abstract class DiffusionStableCommitNameQuery extends DiffusionQuery {
-
-  private $branch;
-  private $repository;
-
-  public function setBranch($branch) {
-    $this->branch = $branch;
-    return $this;
-  }
-  public function getBranch() {
-    return $this->branch;
-  }
-
-  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 load() {
-    return $this->executeQuery();
-  }
-}
Index: src/applications/diffusion/query/stablecommitname/DiffusionSvnStableCommitNameQuery.php
===================================================================
--- src/applications/diffusion/query/stablecommitname/DiffusionSvnStableCommitNameQuery.php
+++ /dev/null
@@ -1,23 +0,0 @@
-<?php
-
-final class DiffusionSvnStableCommitNameQuery
-extends DiffusionStableCommitNameQuery {
-
-  protected function executeQuery() {
-    $repository = $this->getRepository();
-
-    $commit = id(new PhabricatorRepositoryCommit())
-      ->loadOneWhere(
-        'repositoryID = %d ORDER BY epoch DESC LIMIT 1',
-        $repository->getID());
-    if ($commit) {
-      $stable_commit_name = $commit->getCommitIdentifier();
-    } else {
-      // For new repositories, we may not have parsed any commits yet. Call
-      // the stable commit "1" and avoid fataling.
-      $stable_commit_name = 1;
-    }
-
-    return $stable_commit_name;
-  }
-}
Index: src/applications/diffusion/request/DiffusionRequest.php
===================================================================
--- src/applications/diffusion/request/DiffusionRequest.php
+++ src/applications/diffusion/request/DiffusionRequest.php
@@ -18,7 +18,6 @@
   protected $symbolicCommit;
   protected $commit;
   protected $commitType = 'commit';
-  protected $tagContent;
   protected $branch;
   protected $lint;
 
@@ -263,10 +262,6 @@
       $this->getArcanistBranch());
   }
 
-  public function getTagContent() {
-    return $this->tagContent;
-  }
-
   public function loadCommit() {
     if (empty($this->repositoryCommit)) {
       $repository = $this->getRepository();
@@ -624,26 +619,17 @@
   }
 
   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();
+    $results = $this->resolveRefs(array($this->commit));
+    $matches = idx($results, $this->commit, array());
+    if (count($results) !== 1) {
+      throw new Exception(
+        pht('Ref "%s" is ambiguous or does not exist.', $this->commit));
     }
 
-    $this->commit = $commit_data['commit'];
-    $this->commitType = $commit_data['commitType'];
-    $this->tagContent = $commit_data['tagContent'];
+    $match = head($matches);
+
+    $this->commit = $match['identifier'];
+    $this->commitType = $match['type'];
   }
 
   public function getCommitType() {
@@ -653,20 +639,43 @@
   private function queryStableCommitName() {
     if ($this->commit) {
       $this->stableCommitName = $this->commit;
-    } else if ($this->shouldInitFromConduit()) {
-      $this->stableCommitName = DiffusionQuery::callConduitWithDiffusionRequest(
+      return $this->stableCommitName;
+    }
+
+    if ($this->getSupportsBranches()) {
+      $branch = $this->getBranch();
+    } else {
+      $branch = 'HEAD';
+    }
+
+    $results = $this->resolveRefs(array($branch));
+
+    $matches = idx($results, $branch, array());
+    if (count($matches) !== 1) {
+      throw new Exception(
+        pht('Ref "%s" is ambiguous or does not exist.', $branch));
+    }
+
+    $this->stableCommitName = idx(head($matches), 'identifier');
+    return $this->stableCommitName;
+  }
+
+  private function resolveRefs(array $refs) {
+    if ($this->shouldInitFromConduit()) {
+      return DiffusionQuery::callConduitWithDiffusionRequest(
         $this->getUser(),
         $this,
-        'diffusion.stablecommitnamequery',
+        'diffusion.resolverefs',
         array(
-          'branch' => $this->getBranch()
+          'refs' => $refs,
         ));
     } else {
-      $query = DiffusionStableCommitNameQuery::newFromRepository(
-        $this->getRepository());
-      $query->setBranch($this->getBranch());
-      $this->stableCommitName = $query->load();
+      return id(new DiffusionLowLevelResolveRefsQuery())
+        ->setRepository($this->getRepository())
+        ->withRefs($refs)
+        ->execute();
     }
-    return $this->stableCommitName;
   }
+
+
 }