diff --git a/src/internationalization/ArcanistUSEnglishTranslation.php b/src/internationalization/ArcanistUSEnglishTranslation.php
index 3b2c7141..04140399 100644
--- a/src/internationalization/ArcanistUSEnglishTranslation.php
+++ b/src/internationalization/ArcanistUSEnglishTranslation.php
@@ -1,74 +1,84 @@
 <?php
 
 final class ArcanistUSEnglishTranslation extends PhutilTranslation {
 
   public function getLocaleCode() {
     return 'en_US';
   }
 
   protected function getTranslations() {
     return array(
       '%s locally modified path(s) are not included in this revision:' => array(
         'A locally modified path is not included in this revision:',
         'Locally modified paths are not included in this revision:',
       ),
       'These %s path(s) will NOT be committed. Commit this revision '.
       'anyway?' => array(
         'This path will NOT be committed. Commit this revision anyway?',
         'These paths will NOT be committed. Commit this revision anyway?',
       ),
       'Revision includes changes to %s path(s) that do not exist:' => array(
         'Revision includes changes to a path that does not exist:',
         'Revision includes changes to paths that do not exist:',
       ),
 
       'This diff includes %s file(s) which are not valid UTF-8 (they contain '.
       'invalid byte sequences). You can either stop this workflow and fix '.
       'these files, or continue. If you continue, these files will be '.
       'marked as binary.' => array(
         'This diff includes a file which is not valid UTF-8 (it has invalid '.
           'byte sequences). You can either stop this workflow and fix it, or '.
           'continue. If you continue, this file will be marked as binary.',
         'This diff includes files which are not valid UTF-8 (they contain '.
           'invalid byte sequences). You can either stop this workflow and fix '.
           'these files, or continue. If you continue, these files will be '.
           'marked as binary.',
       ),
       '%d AFFECTED FILE(S)' => array('AFFECTED FILE', 'AFFECTED FILES'),
       'Do you want to mark these %s file(s) as binary and continue?' => array(
         'Do you want to mark this file as binary and continue?',
         'Do you want to mark these files as binary and continue?',
       ),
 
       'Do you want to amend these %s change(s) to the current commit?' => array(
         'Do you want to amend this change to the current commit?',
         'Do you want to amend these changes to the current commit?',
       ),
 
       'Do you want to create a new commit with these %s change(s)?' => array(
         'Do you want to create a new commit with this change?',
         'Do you want to create a new commit with these changes?',
       ),
 
       '(To ignore these %s change(s), add them to "%s".)' => array(
         '(To ignore this change, add it to "%2$s".)',
         '(To ignore these changes, add them to "%2$s".)',
       ),
 
       '%s line(s)' => array('line', 'lines'),
 
       '%d test(s)' => array('%d test', '%d tests'),
 
       '%d assertion(s) passed.' => array(
         '%d assertion passed.',
         '%d assertions passed.',
       ),
 
       'Ignore these %s untracked file(s) and continue?' => array(
         'Ignore this untracked file and continue?',
         'Ignore these untracked files and continue?',
       ),
+
+      '%s submodule(s) have uncommitted or untracked changes:' => array(
+        'A submodule has uncommitted or untracked changes:',
+        'Submodules have uncommitted or untracked changes:',
+      ),
+
+      'Ignore the changes to these %s submodule(s) and continue?' => array(
+        'Ignore the changes to this submodule and continue?',
+        'Ignore the changes to these submodules and continue?',
+      ),
     );
   }
 
 }
diff --git a/src/lint/ArcanistLintMessage.php b/src/lint/ArcanistLintMessage.php
index d4de43b8..29f9ab92 100644
--- a/src/lint/ArcanistLintMessage.php
+++ b/src/lint/ArcanistLintMessage.php
@@ -1,259 +1,276 @@
 <?php
 
 /**
  * Message emitted by a linter, like an error or warning.
  */
 final class ArcanistLintMessage extends Phobject {
 
   protected $path;
   protected $line;
   protected $char;
   protected $code;
   protected $severity;
   protected $name;
   protected $description;
   protected $originalText;
   protected $replacementText;
   protected $appliedToDisk;
   protected $dependentMessages = array();
   protected $otherLocations = array();
   protected $obsolete;
   protected $granularity;
   protected $bypassChangedLineFiltering;
 
   public static function newFromDictionary(array $dict) {
     $message = new ArcanistLintMessage();
 
     $message->setPath($dict['path']);
     $message->setLine($dict['line']);
     $message->setChar($dict['char']);
     $message->setCode($dict['code']);
     $message->setSeverity($dict['severity']);
     $message->setName($dict['name']);
     $message->setDescription($dict['description']);
     if (isset($dict['original'])) {
       $message->setOriginalText($dict['original']);
     }
     if (isset($dict['replacement'])) {
       $message->setReplacementText($dict['replacement']);
     }
     $message->setGranularity(idx($dict, 'granularity'));
     $message->setOtherLocations(idx($dict, 'locations', array()));
     if (isset($dict['bypassChangedLineFiltering'])) {
       $message->bypassChangedLineFiltering($dict['bypassChangedLineFiltering']);
     }
     return $message;
   }
 
   public function toDictionary() {
     return array(
       'path'        => $this->getPath(),
       'line'        => $this->getLine(),
       'char'        => $this->getChar(),
       'code'        => $this->getCode(),
       'severity'    => $this->getSeverity(),
       'name'        => $this->getName(),
       'description' => $this->getDescription(),
       'original'    => $this->getOriginalText(),
       'replacement' => $this->getReplacementText(),
       'granularity' => $this->getGranularity(),
       'locations'   => $this->getOtherLocations(),
       'bypassChangedLineFiltering' => $this->shouldBypassChangedLineFiltering(),
     );
   }
 
   public function setPath($path) {
     $this->path = $path;
     return $this;
   }
 
   public function getPath() {
     return $this->path;
   }
 
   public function setLine($line) {
     $this->line = $this->validateInteger($line, 'setLine');
     return $this;
   }
 
   public function getLine() {
     return $this->line;
   }
 
   public function setChar($char) {
     $this->char = $this->validateInteger($char, 'setChar');
     return $this;
   }
 
   public function getChar() {
     return $this->char;
   }
 
   public function setCode($code) {
+    $code = (string)$code;
+
+    $maximum_bytes = 128;
+    $actual_bytes = strlen($code);
+
+    if ($actual_bytes > $maximum_bytes) {
+      throw new Exception(
+        pht(
+          'Parameter ("%s") passed to "%s" when constructing a lint message '.
+          'must be a scalar with a maximum string length of %s bytes, but is '.
+          '%s bytes in length.',
+          $code,
+          'setCode()',
+          new PhutilNumber($maximum_bytes),
+          new PhutilNumber($actual_bytes)));
+    }
+
     $this->code = $code;
     return $this;
   }
 
   public function getCode() {
     return $this->code;
   }
 
   public function setSeverity($severity) {
     $this->severity = $severity;
     return $this;
   }
 
   public function getSeverity() {
     return $this->severity;
   }
 
   public function setName($name) {
     $this->name = $name;
     return $this;
   }
 
   public function getName() {
     return $this->name;
   }
 
   public function setDescription($description) {
     $this->description = $description;
     return $this;
   }
 
   public function getDescription() {
     return $this->description;
   }
 
   public function setOriginalText($original) {
     $this->originalText = $original;
     return $this;
   }
 
   public function getOriginalText() {
     return $this->originalText;
   }
 
   public function setReplacementText($replacement) {
     $this->replacementText = $replacement;
     return $this;
   }
 
   public function getReplacementText() {
     return $this->replacementText;
   }
 
   /**
    * @param dict Keys 'path', 'line', 'char', 'original'.
    */
   public function setOtherLocations(array $locations) {
     assert_instances_of($locations, 'array');
     $this->otherLocations = $locations;
     return $this;
   }
 
   public function getOtherLocations() {
     return $this->otherLocations;
   }
 
   public function isError() {
     return $this->getSeverity() == ArcanistLintSeverity::SEVERITY_ERROR;
   }
 
   public function isWarning() {
     return $this->getSeverity() == ArcanistLintSeverity::SEVERITY_WARNING;
   }
 
   public function isAutofix() {
     return $this->getSeverity() == ArcanistLintSeverity::SEVERITY_AUTOFIX;
   }
 
   public function hasFileContext() {
     return ($this->getLine() !== null);
   }
 
   public function setObsolete($obsolete) {
     $this->obsolete = $obsolete;
     return $this;
   }
 
   public function getObsolete() {
     return $this->obsolete;
   }
 
   public function isPatchable() {
     return ($this->getReplacementText() !== null) &&
            ($this->getReplacementText() !== $this->getOriginalText());
   }
 
   public function didApplyPatch() {
     if ($this->appliedToDisk) {
       return $this;
     }
     $this->appliedToDisk = true;
     foreach ($this->dependentMessages as $message) {
       $message->didApplyPatch();
     }
     return $this;
   }
 
   public function isPatchApplied() {
     return $this->appliedToDisk;
   }
 
   public function setGranularity($granularity) {
     $this->granularity = $granularity;
     return $this;
   }
 
   public function getGranularity() {
     return $this->granularity;
   }
 
   public function setDependentMessages(array $messages) {
     assert_instances_of($messages, __CLASS__);
     $this->dependentMessages = $messages;
     return $this;
   }
 
   public function setBypassChangedLineFiltering($bypass_changed_lines) {
     $this->bypassChangedLineFiltering = $bypass_changed_lines;
     return $this;
   }
 
   public function shouldBypassChangedLineFiltering() {
     return $this->bypassChangedLineFiltering;
   }
 
   /**
    * Validate an integer-like value, returning a strict integer.
    *
    * Further on, the pipeline is strict about types. We want to be a little
    * less strict in linters themselves, since they often parse command line
    * output or XML and will end up with string representations of numbers.
    *
    * @param mixed Integer or digit string.
    * @return int Integer.
    */
   private function validateInteger($value, $caller) {
     if ($value === null) {
       // This just means that we don't have any information.
       return null;
     }
 
     // Strings like "234" are fine, coerce them to integers.
     if (is_string($value) && preg_match('/^\d+\z/', $value)) {
       $value = (int)$value;
     }
 
     if (!is_int($value)) {
       throw new Exception(
         pht(
           'Parameter passed to "%s" must be an integer.',
           $caller.'()'));
     }
 
     return $value;
   }
 
 }
diff --git a/src/lint/engine/ArcanistLintEngine.php b/src/lint/engine/ArcanistLintEngine.php
index 4a092fdb..0bef3e0a 100644
--- a/src/lint/engine/ArcanistLintEngine.php
+++ b/src/lint/engine/ArcanistLintEngine.php
@@ -1,602 +1,617 @@
 <?php
 
 /**
  * Manages lint execution. When you run 'arc lint' or 'arc diff', Arcanist
  * attempts to run lint rules using a lint engine.
  *
  * Lint engines are high-level strategic classes which do not contain any
  * actual linting rules. Linting rules live in `Linter` classes. The lint
  * engine builds and configures linters.
  *
  * Most modern linters can be configured with an `.arclint` file, which is
  * managed by the builtin @{class:ArcanistConfigurationDrivenLintEngine}.
  * Consult the documentation for more information on these files.
  *
  * In the majority of cases, you do not need to write a custom lint engine.
  * For example, to add new rules for a new language, write a linter instead.
  * However, if you have a very advanced or specialized use case, you can write
  * a custom lint engine by extending this class; custom lint engines are more
  * powerful but much more complex than the builtin engines.
  *
  * The lint engine is given a list of paths (generally, the paths that you
  * modified in your change) and determines which linters to run on them. The
  * linters themselves are responsible for actually analyzing file text and
  * finding warnings and errors. For example, if the modified paths include some
  * JS files and some Python files, you might want to run JSLint on the JS files
  * and PyLint on the Python files.
  *
  * You can also run multiple linters on a single file. For instance, you might
  * run one linter on all text files to make sure they don't have trailing
  * whitespace, or enforce tab vs space rules, or make sure there are enough
  * curse words in them.
  *
  * You can test an engine like this:
  *
  *   arc lint --engine YourLintEngineClassName --lintall some_file.py
  *
  * ...which will show you all the lint issues raised in the file.
  *
  * See @{article@phabricator:Arcanist User Guide: Customizing Lint, Unit Tests
  * and Workflows} for more information about configuring lint engines.
  */
 abstract class ArcanistLintEngine extends Phobject {
 
   protected $workingCopy;
   protected $paths = array();
   protected $fileData = array();
 
   protected $charToLine = array();
   protected $lineToFirstChar = array();
   private $cachedResults;
   private $cacheVersion;
   private $repositoryVersion;
   private $results = array();
   private $stopped = array();
   private $minimumSeverity = ArcanistLintSeverity::SEVERITY_DISABLED;
 
   private $changedLines = array();
 
   private $enableAsyncLint = false;
   private $configurationManager;
 
   private $linterResources = array();
 
   public function __construct() {}
 
   final public function setConfigurationManager(
     ArcanistConfigurationManager $configuration_manager) {
     $this->configurationManager = $configuration_manager;
     return $this;
   }
 
   final public function getConfigurationManager() {
     return $this->configurationManager;
   }
 
   final public function setWorkingCopy(
     ArcanistWorkingCopyIdentity $working_copy) {
     $this->workingCopy = $working_copy;
     return $this;
   }
 
   final public function getWorkingCopy() {
     return $this->workingCopy;
   }
 
   final public function setPaths($paths) {
     $this->paths = $paths;
     return $this;
   }
 
   public function getPaths() {
     return $this->paths;
   }
 
   final public function setPathChangedLines($path, $changed) {
     if ($changed === null) {
       $this->changedLines[$path] = null;
     } else {
       $this->changedLines[$path] = array_fill_keys($changed, true);
     }
     return $this;
   }
 
   final public function getPathChangedLines($path) {
     return idx($this->changedLines, $path);
   }
 
   final public function setFileData($data) {
     $this->fileData = $data + $this->fileData;
     return $this;
   }
 
   final public function setEnableAsyncLint($enable_async_lint) {
     $this->enableAsyncLint = $enable_async_lint;
     return $this;
   }
 
   final public function getEnableAsyncLint() {
     return $this->enableAsyncLint;
   }
 
   final public function loadData($path) {
     if (!isset($this->fileData[$path])) {
       $disk_path = $this->getFilePathOnDisk($path);
       $this->fileData[$path] = Filesystem::readFile($disk_path);
     }
     return $this->fileData[$path];
   }
 
   public function pathExists($path) {
     $disk_path = $this->getFilePathOnDisk($path);
     return Filesystem::pathExists($disk_path);
   }
 
   final public function isDirectory($path) {
     $disk_path = $this->getFilePathOnDisk($path);
     return is_dir($disk_path);
   }
 
   final public function isBinaryFile($path) {
     try {
       $data = $this->loadData($path);
     } catch (Exception $ex) {
       return false;
     }
 
     return ArcanistDiffUtils::isHeuristicBinaryFile($data);
   }
 
   final public function isSymbolicLink($path) {
     return is_link($this->getFilePathOnDisk($path));
   }
 
   final public function getFilePathOnDisk($path) {
     return Filesystem::resolvePath(
       $path,
       $this->getWorkingCopy()->getProjectRoot());
   }
 
   final public function setMinimumSeverity($severity) {
     $this->minimumSeverity = $severity;
     return $this;
   }
 
   final public function run() {
     $linters = $this->buildLinters();
     if (!$linters) {
       throw new ArcanistNoEffectException(pht('No linters to run.'));
     }
 
     foreach ($linters as $key => $linter) {
       $linter->setLinterID($key);
     }
 
     $linters = msort($linters, 'getLinterPriority');
     foreach ($linters as $linter) {
       $linter->setEngine($this);
     }
 
     $have_paths = false;
     foreach ($linters as $linter) {
       if ($linter->getPaths()) {
         $have_paths = true;
         break;
       }
     }
 
     if (!$have_paths) {
       throw new ArcanistNoEffectException(pht('No paths are lintable.'));
     }
 
     $versions = array($this->getCacheVersion());
 
     foreach ($linters as $linter) {
       $version = get_class($linter).':'.$linter->getCacheVersion();
 
       $symbols = id(new PhutilSymbolLoader())
         ->setType('class')
         ->setName(get_class($linter))
         ->selectSymbolsWithoutLoading();
       $symbol = idx($symbols, 'class$'.get_class($linter));
       if ($symbol) {
         $version .= ':'.md5_file(
           phutil_get_library_root($symbol['library']).'/'.$symbol['where']);
       }
 
       $versions[] = $version;
     }
 
     $this->cacheVersion = crc32(implode("\n", $versions));
 
     $runnable = $this->getRunnableLinters($linters);
 
     $this->stopped = array();
 
     $exceptions = $this->executeLinters($runnable);
 
     foreach ($runnable as $linter) {
       foreach ($linter->getLintMessages() as $message) {
+        $this->validateLintMessage($linter, $message);
+
         if (!$this->isSeverityEnabled($message->getSeverity())) {
           continue;
         }
         if (!$this->isRelevantMessage($message)) {
           continue;
         }
         $message->setGranularity($linter->getCacheGranularity());
         $result = $this->getResultForPath($message->getPath());
         $result->addMessage($message);
       }
     }
 
     if ($this->cachedResults) {
       foreach ($this->cachedResults as $path => $messages) {
         $messages = idx($messages, $this->cacheVersion, array());
         $repository_version = idx($messages, 'repository_version');
         unset($messages['stopped']);
         unset($messages['repository_version']);
         foreach ($messages as $message) {
           $use_cache = $this->shouldUseCache(
             idx($message, 'granularity'),
             $repository_version);
           if ($use_cache) {
             $this->getResultForPath($path)->addMessage(
               ArcanistLintMessage::newFromDictionary($message));
           }
         }
       }
     }
 
     foreach ($this->results as $path => $result) {
       $disk_path = $this->getFilePathOnDisk($path);
       $result->setFilePathOnDisk($disk_path);
       if (isset($this->fileData[$path])) {
         $result->setData($this->fileData[$path]);
       } else if ($disk_path && Filesystem::pathExists($disk_path)) {
         // TODO: this may cause us to, e.g., load a large binary when we only
         // raised an error about its filename. We could refine this by looking
         // through the lint messages and doing this load only if any of them
         // have original/replacement text or something like that.
         try {
           $this->fileData[$path] = Filesystem::readFile($disk_path);
           $result->setData($this->fileData[$path]);
         } catch (FilesystemException $ex) {
           // Ignore this, it's noncritical that we access this data and it
           // might be unreadable or a directory or whatever else for plenty
           // of legitimate reasons.
         }
       }
     }
 
     if ($exceptions) {
       throw new PhutilAggregateException(
         pht('Some linters failed:'),
         $exceptions);
     }
 
     return $this->results;
   }
 
   final public function isSeverityEnabled($severity) {
     $minimum = $this->minimumSeverity;
     return ArcanistLintSeverity::isAtLeastAsSevere($severity, $minimum);
   }
 
   final private function shouldUseCache(
     $cache_granularity,
     $repository_version) {
 
     switch ($cache_granularity) {
       case ArcanistLinter::GRANULARITY_FILE:
         return true;
       case ArcanistLinter::GRANULARITY_DIRECTORY:
       case ArcanistLinter::GRANULARITY_REPOSITORY:
         return ($this->repositoryVersion == $repository_version);
       default:
         return false;
     }
   }
 
   /**
    * @param dict<string path, dict<string version, list<dict message>>>
    * @return this
    */
   final public function setCachedResults(array $results) {
     $this->cachedResults = $results;
     return $this;
   }
 
   final public function getResults() {
     return $this->results;
   }
 
   final public function getStoppedPaths() {
     return $this->stopped;
   }
 
   abstract public function buildLinters();
 
   final public function setRepositoryVersion($version) {
     $this->repositoryVersion = $version;
     return $this;
   }
 
   final private function isRelevantMessage(ArcanistLintMessage $message) {
     // When a user runs "arc lint", we default to raising only warnings on
     // lines they have changed (errors are still raised anywhere in the
     // file). The list of $changed lines may be null, to indicate that the
     // path is a directory or a binary file so we should not exclude
     // warnings.
 
     if (!$this->changedLines ||
         $message->isError() ||
         $message->shouldBypassChangedLineFiltering()) {
       return true;
     }
 
     $locations = $message->getOtherLocations();
     $locations[] = $message->toDictionary();
 
     foreach ($locations as $location) {
       $path = idx($location, 'path', $message->getPath());
 
       if (!array_key_exists($path, $this->changedLines)) {
         continue;
       }
 
       $changed = $this->getPathChangedLines($path);
 
       if ($changed === null || !$location['line']) {
         return true;
       }
 
       $last_line = $location['line'];
       if (isset($location['original'])) {
         $last_line += substr_count($location['original'], "\n");
       }
 
       for ($l = $location['line']; $l <= $last_line; $l++) {
         if (!empty($changed[$l])) {
           return true;
         }
       }
     }
 
     return false;
   }
 
   final protected function getResultForPath($path) {
     if (empty($this->results[$path])) {
       $result = new ArcanistLintResult();
       $result->setPath($path);
       $result->setCacheVersion($this->cacheVersion);
       $this->results[$path] = $result;
     }
     return $this->results[$path];
   }
 
   final public function getLineAndCharFromOffset($path, $offset) {
     if (!isset($this->charToLine[$path])) {
       $char_to_line = array();
       $line_to_first_char = array();
 
       $lines = explode("\n", $this->loadData($path));
       $line_number = 0;
       $line_start = 0;
       foreach ($lines as $line) {
         $len = strlen($line) + 1; // Account for "\n".
         $line_to_first_char[] = $line_start;
         $line_start += $len;
         for ($ii = 0; $ii < $len; $ii++) {
           $char_to_line[] = $line_number;
         }
         $line_number++;
       }
       $this->charToLine[$path] = $char_to_line;
       $this->lineToFirstChar[$path] = $line_to_first_char;
     }
 
     $line = $this->charToLine[$path][$offset];
     $char = $offset - $this->lineToFirstChar[$path][$line];
 
     return array($line, $char);
   }
 
   protected function getCacheVersion() {
     return 1;
   }
 
 
   /**
    * Get a named linter resource shared by another linter.
    *
    * This mechanism allows linters to share arbitrary resources, like the
    * results of computation. If several linters need to perform the same
    * expensive computation step, they can use a named resource to synchronize
    * construction of the result so it doesn't need to be built multiple
    * times.
    *
    * @param string  Resource identifier.
    * @param wild    Optionally, default value to return if resource does not
    *                exist.
    * @return wild   Resource, or default value if not present.
    */
   public function getLinterResource($key, $default = null) {
     return idx($this->linterResources, $key, $default);
   }
 
 
   /**
    * Set a linter resource that other linters can access.
    *
    * See @{method:getLinterResource} for a description of this mechanism.
    *
    * @param string Resource identifier.
    * @param wild   Resource.
    * @return this
    */
   public function setLinterResource($key, $value) {
     $this->linterResources[$key] = $value;
     return $this;
   }
 
 
   private function getRunnableLinters(array $linters) {
     assert_instances_of($linters, 'ArcanistLinter');
 
     // TODO: The canRun() mechanism is only used by one linter, and just
     // silently disables the linter. Almost every other linter handles this
     // by throwing `ArcanistMissingLinterException`. Both mechanisms are not
     // ideal; linters which can not run should emit a message, get marked as
     // "skipped", and allow execution to continue. See T7045.
 
     $runnable = array();
     foreach ($linters as $key => $linter) {
       if ($linter->canRun()) {
         $runnable[$key] = $linter;
       }
     }
 
     return $runnable;
   }
 
   private function executeLinters(array $runnable) {
     assert_instances_of($runnable, 'ArcanistLinter');
 
     $all_paths = $this->getPaths();
     $path_chunks = array_chunk($all_paths, 32, $preserve_keys = true);
 
     $exception_lists = array();
     foreach ($path_chunks as $chunk) {
       $exception_lists[] = $this->executeLintersOnChunk($runnable, $chunk);
     }
 
     return array_mergev($exception_lists);
   }
 
 
   private function executeLintersOnChunk(array $runnable, array $path_list) {
     assert_instances_of($runnable, 'ArcanistLinter');
 
     $path_map = array_fuse($path_list);
 
     $exceptions = array();
     $did_lint = array();
     foreach ($runnable as $linter) {
       $linter_id = $linter->getLinterID();
       $paths = $linter->getPaths();
 
       foreach ($paths as $key => $path) {
         // If we aren't running this path in the current chunk of paths,
         // skip it completely.
         if (empty($path_map[$path])) {
           unset($paths[$key]);
           continue;
         }
 
         // Make sure each path has a result generated, even if it is empty
         // (i.e., the file has no lint messages).
         $result = $this->getResultForPath($path);
 
         // If a linter has stopped all other linters for this path, don't
         // actually run the linter.
         if (isset($this->stopped[$path])) {
           unset($paths[$key]);
           continue;
         }
 
         // If we have a cached result for this path, don't actually run the
         // linter.
         if (isset($this->cachedResults[$path][$this->cacheVersion])) {
           $cached_result = $this->cachedResults[$path][$this->cacheVersion];
 
           $use_cache = $this->shouldUseCache(
             $linter->getCacheGranularity(),
             idx($cached_result, 'repository_version'));
 
           if ($use_cache) {
             unset($paths[$key]);
             if (idx($cached_result, 'stopped') == $linter_id) {
               $this->stopped[$path] = $linter_id;
             }
           }
         }
       }
 
       $paths = array_values($paths);
 
       if (!$paths) {
         continue;
       }
 
       try {
         $this->executeLinterOnPaths($linter, $paths);
         $did_lint[] = array($linter, $paths);
       } catch (Exception $ex) {
         $exceptions[] = $ex;
       }
     }
 
     foreach ($did_lint as $info) {
       list($linter, $paths) = $info;
       try {
         $this->executeDidLintOnPaths($linter, $paths);
       } catch (Exception $ex) {
         $exceptions[] = $ex;
       }
     }
 
     return $exceptions;
   }
 
   private function beginLintServiceCall(ArcanistLinter $linter, array $paths) {
     $profiler = PhutilServiceProfiler::getInstance();
 
     return $profiler->beginServiceCall(
       array(
         'type' => 'lint',
         'linter' => $linter->getInfoName(),
         'paths' => $paths,
       ));
   }
 
   private function endLintServiceCall($call_id) {
     $profiler = PhutilServiceProfiler::getInstance();
     $profiler->endServiceCall($call_id, array());
   }
 
   private function executeLinterOnPaths(ArcanistLinter $linter, array $paths) {
     $call_id = $this->beginLintServiceCall($linter, $paths);
 
     try {
       $linter->willLintPaths($paths);
       foreach ($paths as $path) {
         $linter->setActivePath($path);
         $linter->lintPath($path);
         if ($linter->didStopAllLinters()) {
           $this->stopped[$path] = $linter->getLinterID();
         }
       }
     } catch (Exception $ex) {
       $this->endLintServiceCall($call_id);
       throw $ex;
     }
 
     $this->endLintServiceCall($call_id);
   }
 
   private function executeDidLintOnPaths(ArcanistLinter $linter, array $paths) {
     $call_id = $this->beginLintServiceCall($linter, $paths);
 
     try {
       $linter->didLintPaths($paths);
     } catch (Exception $ex) {
       $this->endLintServiceCall($call_id);
       throw $ex;
     }
 
     $this->endLintServiceCall($call_id);
   }
 
+  private function validateLintMessage(
+    ArcanistLinter $linter,
+    ArcanistLintMessage $message) {
+
+    $name = $message->getName();
+    if (!strlen($name)) {
+      throw new Exception(
+        pht(
+          'Linter "%s" generated a lint message that is invalid because it '.
+          'does not have a name. Lint messages must have a name.',
+          get_class($linter)));
+    }
+  }
 
 }
diff --git a/src/lint/linter/ArcanistPhpcsLinter.php b/src/lint/linter/ArcanistPhpcsLinter.php
index da3d118c..9556ea0a 100644
--- a/src/lint/linter/ArcanistPhpcsLinter.php
+++ b/src/lint/linter/ArcanistPhpcsLinter.php
@@ -1,148 +1,150 @@
 <?php
 
 /**
  * Uses "PHP_CodeSniffer" to detect checkstyle errors in PHP code.
  */
 final class ArcanistPhpcsLinter extends ArcanistExternalLinter {
 
   private $standard;
 
   public function getInfoName() {
     return 'PHP_CodeSniffer';
   }
 
   public function getInfoURI() {
     return 'http://pear.php.net/package/PHP_CodeSniffer/';
   }
 
   public function getInfoDescription() {
     return pht(
       'PHP_CodeSniffer tokenizes PHP, JavaScript and CSS files and '.
       'detects violations of a defined set of coding standards.');
   }
 
   public function getLinterName() {
     return 'PHPCS';
   }
 
   public function getLinterConfigurationName() {
     return 'phpcs';
   }
 
   public function getInstallInstructions() {
     return pht('Install PHPCS with `%s`.', 'pear install PHP_CodeSniffer');
   }
 
   public function getLinterConfigurationOptions() {
     $options = array(
       'phpcs.standard' => array(
         'type' => 'optional string',
         'help' => pht('The name or path of the coding standard to use.'),
       ),
     );
 
     return $options + parent::getLinterConfigurationOptions();
   }
 
   public function setLinterConfigurationValue($key, $value) {
     switch ($key) {
       case 'phpcs.standard':
         $this->standard = $value;
         return;
 
       default:
         return parent::setLinterConfigurationValue($key, $value);
     }
   }
 
   protected function getMandatoryFlags() {
     $options = array('--report=xml');
 
     if ($this->standard) {
       $options[] = '--standard='.$this->standard;
     }
 
     return $options;
   }
 
   public function getDefaultBinary() {
     return 'phpcs';
   }
 
   public function getVersion() {
     list($stdout) = execx('%C --version', $this->getExecutableCommand());
 
     $matches = array();
     $regex = '/^PHP_CodeSniffer version (?P<version>\d+\.\d+\.\d+)\b/';
     if (preg_match($regex, $stdout, $matches)) {
       return $matches['version'];
     } else {
       return false;
     }
   }
 
   protected function parseLinterOutput($path, $err, $stdout, $stderr) {
     // NOTE: Some version of PHPCS after 1.4.6 stopped printing a valid, empty
     // XML document to stdout in the case of no errors. If PHPCS exits with
     // error 0, just ignore output.
     if (!$err) {
       return array();
     }
 
     $report_dom = new DOMDocument();
     $ok = @$report_dom->loadXML($stdout);
     if (!$ok) {
       return false;
     }
 
     $files = $report_dom->getElementsByTagName('file');
     $messages = array();
     foreach ($files as $file) {
       foreach ($file->childNodes as $child) {
         if (!($child instanceof DOMElement)) {
           continue;
         }
 
         if ($child->tagName == 'error') {
           $prefix = 'E';
         } else {
           $prefix = 'W';
         }
 
-        $code = 'PHPCS.'.$prefix.'.'.$child->getAttribute('source');
-
-        $message = new ArcanistLintMessage();
-        $message->setPath($path);
-        $message->setLine($child->getAttribute('line'));
-        $message->setChar($child->getAttribute('column'));
-        $message->setCode($code);
-        $message->setDescription($child->nodeValue);
-        $message->setSeverity($this->getLintMessageSeverity($code));
+        $source = $child->getAttribute('source');
+        $code = 'PHPCS.'.$prefix.'.'.$source;
+
+        $message = id(new ArcanistLintMessage())
+          ->setPath($path)
+          ->setName($source)
+          ->setLine($child->getAttribute('line'))
+          ->setChar($child->getAttribute('column'))
+          ->setCode($code)
+          ->setDescription($child->nodeValue)
+          ->setSeverity($this->getLintMessageSeverity($code));
 
         $messages[] = $message;
       }
     }
 
     return $messages;
   }
 
   protected function getDefaultMessageSeverity($code) {
     if (preg_match('/^PHPCS\\.W\\./', $code)) {
       return ArcanistLintSeverity::SEVERITY_WARNING;
     } else {
       return ArcanistLintSeverity::SEVERITY_ERROR;
     }
   }
 
   protected function getLintCodeFromLinterConfigurationKey($code) {
     if (!preg_match('/^PHPCS\\.(E|W)\\./', $code)) {
       throw new Exception(
         pht(
           "Invalid severity code '%s', should begin with '%s.'.",
           $code,
           'PHPCS'));
     }
     return $code;
   }
 
 }
diff --git a/src/repository/api/ArcanistGitAPI.php b/src/repository/api/ArcanistGitAPI.php
index f5ceae9c..84ac017f 100644
--- a/src/repository/api/ArcanistGitAPI.php
+++ b/src/repository/api/ArcanistGitAPI.php
@@ -1,1302 +1,1336 @@
 <?php
 
 /**
  * Interfaces with Git working copies.
  */
 final class ArcanistGitAPI extends ArcanistRepositoryAPI {
 
   private $repositoryHasNoCommits = false;
   const SEARCH_LENGTH_FOR_PARENT_REVISIONS = 16;
 
   /**
    * For the repository's initial commit, 'git diff HEAD^' and similar do
    * not work. Using this instead does work; it is the hash of the empty tree.
    */
   const GIT_MAGIC_ROOT_COMMIT = '4b825dc642cb6eb9a060e54bf8d69288fbee4904';
 
   private $symbolicHeadCommit;
   private $resolvedHeadCommit;
 
   protected function buildLocalFuture(array $argv) {
     $argv[0] = 'git '.$argv[0];
 
     $future = newv('ExecFuture', $argv);
     $future->setCWD($this->getPath());
     return $future;
   }
 
   public function execPassthru($pattern /* , ... */) {
     $args = func_get_args();
 
     static $git = null;
     if ($git === null) {
       if (phutil_is_windows()) {
         // NOTE: On Windows, phutil_passthru() uses 'bypass_shell' because
         // everything goes to hell if we don't. We must provide an absolute
         // path to Git for this to work properly.
         $git = Filesystem::resolveBinary('git');
         $git = csprintf('%s', $git);
       } else {
         $git = 'git';
       }
     }
 
     $args[0] = $git.' '.$args[0];
 
     return call_user_func_array('phutil_passthru', $args);
   }
 
 
   public function getSourceControlSystemName() {
     return 'git';
   }
 
   public function getGitVersion() {
     list($stdout) = $this->execxLocal('--version');
     return rtrim(str_replace('git version ', '', $stdout));
   }
 
   public function getMetadataPath() {
     static $path = null;
     if ($path === null) {
       list($stdout) = $this->execxLocal('rev-parse --git-dir');
       $path = rtrim($stdout, "\n");
       // the output of git rev-parse --git-dir is an absolute path, unless
       // the cwd is the root of the repository, in which case it uses the
       // relative path of .git. If we get this relative path, turn it into
       // an absolute path.
       if ($path === '.git') {
         $path = $this->getPath('.git');
       }
     }
     return $path;
   }
 
   public function getHasCommits() {
     return !$this->repositoryHasNoCommits;
   }
 
   /**
    * Tests if a child commit is descendant of a parent commit.
    * If child and parent are the same, it returns false.
    * @param Child commit SHA.
    * @param Parent commit SHA.
    * @return bool True if the child is a descendant of the parent.
    */
   private function isDescendant($child, $parent) {
     list($common_ancestor) = $this->execxLocal(
       'merge-base %s %s',
       $child,
       $parent);
     $common_ancestor = trim($common_ancestor);
 
     return ($common_ancestor == $parent) && ($common_ancestor != $child);
   }
 
   public function getLocalCommitInformation() {
     if ($this->repositoryHasNoCommits) {
       // Zero commits.
       throw new Exception(
         pht(
           "You can't get local commit information for a repository with no ".
           "commits."));
     } else if ($this->getBaseCommit() == self::GIT_MAGIC_ROOT_COMMIT) {
       // One commit.
       $against = 'HEAD';
     } else {
 
       // 2..N commits. We include commits reachable from HEAD which are
       // not reachable from the base commit; this is consistent with user
       // expectations even though it is not actually the diff range.
       // Particularly:
       //
       //    |
       //    D <----- master branch
       //    |
       //    C  Y <- feature branch
       //    | /|
       //    B  X
       //    | /
       //    A
       //    |
       //
       // If "A, B, C, D" are master, and the user is at Y, when they run
       // "arc diff B" they want (and get) a diff of B vs Y, but they think about
       // this as being the commits X and Y. If we log "B..Y", we only show
       // Y. With "Y --not B", we show X and Y.
 
 
       if ($this->symbolicHeadCommit !== null) {
         $base_commit = $this->getBaseCommit();
         $resolved_base = $this->resolveCommit($base_commit);
 
         $head_commit = $this->symbolicHeadCommit;
         $resolved_head = $this->getHeadCommit();
 
         if (!$this->isDescendant($resolved_head, $resolved_base)) {
           // NOTE: Since the base commit will have been resolved as the
           // merge-base of the specified base and the specified HEAD, we can't
           // easily tell exactly what's wrong with the range.
 
           // For example, `arc diff HEAD --head HEAD^^^` is invalid because it
           // is reversed, but resolving the commit "HEAD" will compute its
           // merge-base with "HEAD^^^", which is "HEAD^^^", so the range will
           // appear empty.
 
           throw new ArcanistUsageException(
             pht(
               'The specified commit range is empty, backward or invalid: the '.
               'base (%s) is not an ancestor of the head (%s). You can not '.
               'diff an empty or reversed commit range.',
               $base_commit,
               $head_commit));
         }
       }
 
       $against = csprintf(
         '%s --not %s',
         $this->getHeadCommit(),
         $this->getBaseCommit());
     }
 
     // NOTE: Windows escaping of "%" symbols apparently is inherently broken;
     // when passed through escapeshellarg() they are replaced with spaces.
 
     // TODO: Learn how cmd.exe works and find some clever workaround?
 
     // NOTE: If we use "%x00", output is truncated in Windows.
 
     list($info) = $this->execxLocal(
       phutil_is_windows()
         ? 'log %C --format=%C --'
         : 'log %C --format=%s --',
       $against,
       // NOTE: "%B" is somewhat new, use "%s%n%n%b" instead.
       '%H%x01%T%x01%P%x01%at%x01%an%x01%aE%x01%s%x01%s%n%n%b%x02');
 
     $commits = array();
 
     $info = trim($info, " \n\2");
     if (!strlen($info)) {
       return array();
     }
 
     $info = explode("\2", $info);
     foreach ($info as $line) {
       list($commit, $tree, $parents, $time, $author, $author_email,
         $title, $message) = explode("\1", trim($line), 8);
       $message = rtrim($message);
 
       $commits[$commit] = array(
         'commit'  => $commit,
         'tree'    => $tree,
         'parents' => array_filter(explode(' ', $parents)),
         'time'    => $time,
         'author'  => $author,
         'summary' => $title,
         'message' => $message,
         'authorEmail' => $author_email,
       );
     }
 
     return $commits;
   }
 
   protected function buildBaseCommit($symbolic_commit) {
     if ($symbolic_commit !== null) {
       if ($symbolic_commit == self::GIT_MAGIC_ROOT_COMMIT) {
         $this->setBaseCommitExplanation(
           pht('you explicitly specified the empty tree.'));
         return $symbolic_commit;
       }
 
       list($err, $merge_base) = $this->execManualLocal(
         'merge-base %s %s',
         $symbolic_commit,
         $this->getHeadCommit());
       if ($err) {
         throw new ArcanistUsageException(
           pht(
             "Unable to find any git commit named '%s' in this repository.",
             $symbolic_commit));
       }
 
       if ($this->symbolicHeadCommit === null) {
         $this->setBaseCommitExplanation(
           pht(
             "it is the merge-base of the explicitly specified base commit ".
             "'%s' and HEAD.",
             $symbolic_commit));
       } else {
         $this->setBaseCommitExplanation(
           pht(
             "it is the merge-base of the explicitly specified base commit ".
             "'%s' and the explicitly specified head commit '%s'.",
             $symbolic_commit,
             $this->symbolicHeadCommit));
       }
 
       return trim($merge_base);
     }
 
     // Detect zero-commit or one-commit repositories. There is only one
     // relative-commit value that makes any sense in these repositories: the
     // empty tree.
     list($err) = $this->execManualLocal('rev-parse --verify HEAD^');
     if ($err) {
       list($err) = $this->execManualLocal('rev-parse --verify HEAD');
       if ($err) {
         $this->repositoryHasNoCommits = true;
       }
 
       if ($this->repositoryHasNoCommits) {
         $this->setBaseCommitExplanation(pht('the repository has no commits.'));
       } else {
         $this->setBaseCommitExplanation(
           pht('the repository has only one commit.'));
       }
 
       return self::GIT_MAGIC_ROOT_COMMIT;
     }
 
     if ($this->getBaseCommitArgumentRules() ||
         $this->getConfigurationManager()->getConfigFromAnySource('base')) {
       $base = $this->resolveBaseCommit();
       if (!$base) {
         throw new ArcanistUsageException(
           pht(
             "None of the rules in your 'base' configuration matched a valid ".
             "commit. Adjust rules or specify which commit you want to use ".
             "explicitly."));
       }
       return $base;
     }
 
     $do_write = false;
     $default_relative = null;
     $working_copy = $this->getWorkingCopyIdentity();
     if ($working_copy) {
       $default_relative = $working_copy->getProjectConfig(
         'git.default-relative-commit');
       $this->setBaseCommitExplanation(
         pht(
           "it is the merge-base of '%s' and HEAD, as specified in '%s' in ".
           "'%s'. This setting overrides other settings.",
           $default_relative,
           'git.default-relative-commit',
           '.arcconfig'));
     }
 
     if (!$default_relative) {
       list($err, $upstream) = $this->execManualLocal(
         'rev-parse --abbrev-ref --symbolic-full-name %s',
         '@{upstream}');
 
       if (!$err) {
         $default_relative = trim($upstream);
         $this->setBaseCommitExplanation(
           pht(
             "it is the merge-base of '%s' (the Git upstream ".
             "of the current branch) HEAD.",
             $default_relative));
       }
     }
 
     if (!$default_relative) {
       $default_relative = $this->readScratchFile('default-relative-commit');
       $default_relative = trim($default_relative);
       if ($default_relative) {
         $this->setBaseCommitExplanation(
           pht(
             "it is the merge-base of '%s' and HEAD, as specified in '%s'.",
             $default_relative,
             '.git/arc/default-relative-commit'));
       }
     }
 
     if (!$default_relative) {
 
       // TODO: Remove the history lesson soon.
 
       echo phutil_console_format(
         "<bg:green>** %s **</bg>\n\n",
         pht('Select a Default Commit Range'));
       echo phutil_console_wrap(
         pht(
           "You're running a command which operates on a range of revisions ".
           "(usually, from some revision to HEAD) but have not specified the ".
           "revision that should determine the start of the range.\n\n".
           "Previously, arc assumed you meant '%s' when you did not specify ".
           "a start revision, but this behavior does not make much sense in ".
           "most workflows outside of Facebook's historic %s workflow.\n\n".
           "arc no longer assumes '%s'. You must specify a relative commit ".
           "explicitly when you invoke a command (e.g., `%s`, not just `%s`) ".
           "or select a default for this working copy.\n\nIn most cases, the ".
           "best default is '%s'. You can also select '%s' to preserve the ".
           "old behavior, or some other remote or branch. But you almost ".
           "certainly want to select 'origin/master'.\n\n".
           "(Technically: the merge-base of the selected revision and HEAD is ".
           "used to determine the start of the commit range.)",
           'HEAD^',
           'git-svn',
           'HEAD^',
           'arc diff HEAD^',
           'arc diff',
           'origin/master',
           'HEAD^'));
 
       $prompt = pht('What default do you want to use? [origin/master]');
       $default = phutil_console_prompt($prompt);
 
       if (!strlen(trim($default))) {
         $default = 'origin/master';
       }
 
       $default_relative = $default;
       $do_write = true;
     }
 
     list($object_type) = $this->execxLocal(
       'cat-file -t %s',
       $default_relative);
 
     if (trim($object_type) !== 'commit') {
       throw new Exception(
         pht(
           "Relative commit '%s' is not the name of a commit!",
           $default_relative));
     }
 
     if ($do_write) {
       // Don't perform this write until we've verified that the object is a
       // valid commit name.
       $this->writeScratchFile('default-relative-commit', $default_relative);
       $this->setBaseCommitExplanation(
         pht(
           "it is the merge-base of '%s' and HEAD, as you just specified.",
           $default_relative));
     }
 
     list($merge_base) = $this->execxLocal(
       'merge-base %s HEAD',
       $default_relative);
 
     return trim($merge_base);
   }
 
   public function getHeadCommit() {
     if ($this->resolvedHeadCommit === null) {
       $this->resolvedHeadCommit = $this->resolveCommit(
         coalesce($this->symbolicHeadCommit, 'HEAD'));
     }
 
     return $this->resolvedHeadCommit;
   }
 
   public function setHeadCommit($symbolic_commit) {
     $this->symbolicHeadCommit = $symbolic_commit;
     $this->reloadCommitRange();
     return $this;
   }
 
   /**
    * Translates a symbolic commit (like "HEAD^") to a commit identifier.
    * @param string_symbol commit.
    * @return string the commit SHA.
    */
   private function resolveCommit($symbolic_commit) {
     list($err, $commit_hash) = $this->execManualLocal(
       'rev-parse %s',
       $symbolic_commit);
 
     if ($err) {
       throw new ArcanistUsageException(
         pht(
           "Unable to find any git commit named '%s' in this repository.",
           $symbolic_commit));
     }
 
     return trim($commit_hash);
   }
 
   private function getDiffFullOptions($detect_moves_and_renames = true) {
     $options = array(
       self::getDiffBaseOptions(),
       '--no-color',
       '--src-prefix=a/',
       '--dst-prefix=b/',
       '-U'.$this->getDiffLinesOfContext(),
     );
 
     if ($detect_moves_and_renames) {
       $options[] = '-M';
       $options[] = '-C';
     }
 
     return implode(' ', $options);
   }
 
   private function getDiffBaseOptions() {
     $options = array(
       // Disable external diff drivers, like graphical differs, since Arcanist
       // needs to capture the diff text.
       '--no-ext-diff',
       // Disable textconv so we treat binary files as binary, even if they have
       // an alternative textual representation. TODO: Ideally, Differential
       // would ship up the binaries for 'arc patch' but display the textconv
       // output in the visual diff.
       '--no-textconv',
     );
     return implode(' ', $options);
   }
 
   /**
    * @param the base revision
    * @param head revision. If this is null, the generated diff will include the
    * working copy
    */
   public function getFullGitDiff($base, $head = null) {
     $options = $this->getDiffFullOptions();
 
     if ($head !== null) {
       list($stdout) = $this->execxLocal(
         "diff {$options} %s %s --",
         $base,
         $head);
     } else {
       list($stdout) = $this->execxLocal(
         "diff {$options} %s --",
         $base);
     }
 
     return $stdout;
   }
 
   /**
    * @param string Path to generate a diff for.
    * @param bool   If true, detect moves and renames. Otherwise, ignore
    *               moves/renames; this is useful because it prompts git to
    *               generate real diff text.
    */
   public function getRawDiffText($path, $detect_moves_and_renames = true) {
     $options = $this->getDiffFullOptions($detect_moves_and_renames);
     list($stdout) = $this->execxLocal(
       "diff {$options} %s -- %s",
       $this->getBaseCommit(),
       $path);
     return $stdout;
   }
 
   private function getBranchNameFromRef($ref) {
     $count = 0;
     $branch = preg_replace('/^refs\/heads\//', '', $ref, 1, $count);
     if ($count !== 1) {
       return null;
     }
 
     return $branch;
   }
 
   public function getBranchName() {
     list($err, $stdout, $stderr) = $this->execManualLocal(
       'symbolic-ref --quiet HEAD');
 
     if ($err === 0) {
       // We expect the branch name to come qualified with a refs/heads/ prefix.
       // Verify this, and strip it.
       $ref = rtrim($stdout);
       $branch = $this->getBranchNameFromRef($ref);
       if (!$branch) {
         throw new Exception(
           pht('Failed to parse %s output!', 'git symbolic-ref'));
       }
       return $branch;
     } else if ($err === 1) {
       // Exit status 1 with --quiet indicates that HEAD is detached.
       return null;
     } else {
       throw new Exception(
         pht('Command %s failed: %s', 'git symbolic-ref', $stderr));
     }
   }
 
   public function getRemoteURI() {
     // "git ls-remote --get-url" is the appropriate plumbing to get the remote
     // URI. "git config remote.origin.url", on the other hand, may not be as
     // accurate (for example, it does not take into account possible URL
     // rewriting rules set by the user through "url.<base>.insteadOf"). However,
     // the --get-url flag requires git 1.7.5.
     $version = $this->getGitVersion();
     if (version_compare($version, '1.7.5', '>=')) {
       list($stdout) = $this->execxLocal('ls-remote --get-url origin');
     } else {
       list($stdout) = $this->execxLocal('config remote.origin.url');
     }
 
     $uri = rtrim($stdout);
     // 'origin' is what ls-remote outputs if no origin remote URI exists
     if (!$uri || $uri === 'origin') {
       return null;
     }
 
     return $uri;
   }
 
   public function getSourceControlPath() {
     // TODO: Try to get something useful here.
     return null;
   }
 
   public function getGitCommitLog() {
     $relative = $this->getBaseCommit();
     if ($this->repositoryHasNoCommits) {
       // No commits yet.
       return '';
     } else if ($relative == self::GIT_MAGIC_ROOT_COMMIT) {
       // First commit.
       list($stdout) = $this->execxLocal(
         'log --format=medium HEAD');
     } else {
       // 2..N commits.
       list($stdout) = $this->execxLocal(
         'log --first-parent --format=medium %s..%s',
         $this->getBaseCommit(),
         $this->getHeadCommit());
     }
     return $stdout;
   }
 
   public function getGitHistoryLog() {
     list($stdout) = $this->execxLocal(
       'log --format=medium -n%d %s',
       self::SEARCH_LENGTH_FOR_PARENT_REVISIONS,
       $this->getBaseCommit());
     return $stdout;
   }
 
   public function getSourceControlBaseRevision() {
     list($stdout) = $this->execxLocal(
       'rev-parse %s',
       $this->getBaseCommit());
     return rtrim($stdout, "\n");
   }
 
   public function getCanonicalRevisionName($string) {
     $match = null;
     if (preg_match('/@([0-9]+)$/', $string, $match)) {
       $stdout = $this->getHashFromFromSVNRevisionNumber($match[1]);
     } else {
       list($stdout) = $this->execxLocal(
         phutil_is_windows()
         ? 'show -s --format=%C %s --'
         : 'show -s --format=%s %s --',
         '%H',
         $string);
     }
     return rtrim($stdout);
   }
 
   private function executeSVNFindRev($input, $vcs) {
     $match = array();
     list($stdout) = $this->execxLocal(
       'svn find-rev %s',
       $input);
     if (!$stdout) {
       throw new ArcanistUsageException(
         pht(
           'Cannot find the %s equivalent of %s.',
           $vcs,
           $input));
     }
     // When git performs a partial-rebuild during svn
     // look-up, we need to parse the final line
     $lines = explode("\n", $stdout);
     $stdout = $lines[count($lines) - 2];
     return rtrim($stdout);
   }
 
   // Convert svn revision number to git hash
   public function getHashFromFromSVNRevisionNumber($revision_id) {
     return $this->executeSVNFindRev('r'.$revision_id, 'Git');
   }
 
 
   // Convert a git hash to svn revision number
   public function getSVNRevisionNumberFromHash($hash) {
     return $this->executeSVNFindRev($hash, 'SVN');
   }
 
 
   protected function buildUncommittedStatus() {
     $diff_options = $this->getDiffBaseOptions();
 
     if ($this->repositoryHasNoCommits) {
       $diff_base = self::GIT_MAGIC_ROOT_COMMIT;
     } else {
       $diff_base = 'HEAD';
     }
 
     // Find uncommitted changes.
     $uncommitted_future = $this->buildLocalFuture(
       array(
         'diff %C --raw %s --',
         $diff_options,
         $diff_base,
       ));
 
     $untracked_future = $this->buildLocalFuture(
       array(
         'ls-files --others --exclude-standard',
       ));
 
     // Unstaged changes
     $unstaged_future = $this->buildLocalFuture(
       array(
         'diff-files --name-only',
       ));
 
     $futures = array(
       $uncommitted_future,
       $untracked_future,
       // NOTE: `git diff-files` races with each of these other commands
       // internally, and resolves with inconsistent results if executed
       // in parallel. To work around this, DO NOT run it at the same time.
       // After the other commands exit, we can start the `diff-files` command.
     );
 
     id(new FutureIterator($futures))->resolveAll();
 
     // We're clear to start the `git diff-files` now.
     $unstaged_future->start();
 
     $result = new PhutilArrayWithDefaultValue();
 
     list($stdout) = $uncommitted_future->resolvex();
-    $uncommitted_files = $this->parseGitStatus($stdout);
+    $uncommitted_files = $this->parseGitRawDiff($stdout);
     foreach ($uncommitted_files as $path => $mask) {
       $result[$path] |= ($mask | self::FLAG_UNCOMMITTED);
     }
 
     list($stdout) = $untracked_future->resolvex();
     $stdout = rtrim($stdout, "\n");
     if (strlen($stdout)) {
       $stdout = explode("\n", $stdout);
       foreach ($stdout as $path) {
         $result[$path] |= self::FLAG_UNTRACKED;
       }
     }
 
     list($stdout, $stderr) = $unstaged_future->resolvex();
     $stdout = rtrim($stdout, "\n");
     if (strlen($stdout)) {
       $stdout = explode("\n", $stdout);
       foreach ($stdout as $path) {
         $result[$path] |= self::FLAG_UNSTAGED;
       }
     }
 
     return $result->toArray();
   }
 
   protected function buildCommitRangeStatus() {
     list($stdout, $stderr) = $this->execxLocal(
       'diff %C --raw %s --',
       $this->getDiffBaseOptions(),
       $this->getBaseCommit());
 
-    return $this->parseGitStatus($stdout);
+    return $this->parseGitRawDiff($stdout);
   }
 
   public function getGitConfig($key, $default = null) {
     list($err, $stdout) = $this->execManualLocal('config %s', $key);
     if ($err) {
       return $default;
     }
     return rtrim($stdout);
   }
 
   public function getAuthor() {
     list($stdout) = $this->execxLocal('var GIT_AUTHOR_IDENT');
     return preg_replace('/\s+<.*/', '', rtrim($stdout, "\n"));
   }
 
   public function addToCommit(array $paths) {
     $this->execxLocal(
       'add -A -- %Ls',
       $paths);
     $this->reloadWorkingCopy();
     return $this;
   }
 
   public function doCommit($message) {
     $tmp_file = new TempFile();
     Filesystem::writeFile($tmp_file, $message);
 
     // NOTE: "--allow-empty-message" was introduced some time after 1.7.0.4,
     // so we do not provide it and thus require a message.
 
     $this->execxLocal(
       'commit -F %s',
       $tmp_file);
 
     $this->reloadWorkingCopy();
 
     return $this;
   }
 
   public function amendCommit($message = null) {
     if ($message === null) {
       $this->execxLocal('commit --amend --allow-empty -C HEAD');
     } else {
       $tmp_file = new TempFile();
       Filesystem::writeFile($tmp_file, $message);
       $this->execxLocal(
         'commit --amend --allow-empty -F %s',
         $tmp_file);
     }
 
     $this->reloadWorkingCopy();
     return $this;
   }
 
-  private function parseGitStatus($status, $full = false) {
+  private function parseGitRawDiff($status, $full = false) {
     static $flags = array(
       'A' => self::FLAG_ADDED,
       'M' => self::FLAG_MODIFIED,
       'D' => self::FLAG_DELETED,
     );
 
     $status = trim($status);
     $lines = array();
     foreach (explode("\n", $status) as $line) {
       if ($line) {
         $lines[] = preg_split("/[ \t]/", $line, 6);
       }
     }
 
     $files = array();
     foreach ($lines as $line) {
       $mask = 0;
+
+      // "git diff --raw" lines begin with a ":" character.
+      $old_mode = ltrim($line[0], ':');
+      $new_mode = $line[1];
+
+      // The hashes may be padded with "." characters for alignment. Discard
+      // them.
+      $old_hash = rtrim($line[2], '.');
+      $new_hash = rtrim($line[3], '.');
+
       $flag = $line[4];
       $file = $line[5];
-      foreach ($flags as $key => $bits) {
-        if ($flag == $key) {
-          $mask |= $bits;
-        }
+
+      $new_value = intval($new_mode, 8);
+      $is_submodule = (($new_value & 0160000) === 0160000);
+
+      if (($is_submodule) &&
+          ($flag == 'M') &&
+          ($old_hash === $new_hash) &&
+          ($old_mode === $new_mode)) {
+        // See T9455. We see this submodule as "modified", but the old and new
+        // hashes are the same and the old and new modes are the same, so we
+        // don't directly see a modification.
+
+        // We can end up here if we have a submodule which has uncommitted
+        // changes inside of it (for example, the user has added untracked
+        // files or made uncommitted changes to files in the submodule). In
+        // this case, we set a different flag because we can't meaningfully
+        // give users the same prompt.
+
+        // Note that if the submodule has real changes from the parent
+        // perspective (the base commit has changed) and also has uncommitted
+        // changes, we'll only see the real changes and miss the uncommitted
+        // changes. At the time of writing, there is no reasonable porcelain
+        // for finding those changes, and the impact of this error seems small.
+
+        $mask |= self::FLAG_EXTERNALS;
+      } else if (isset($flags[$flag])) {
+        $mask |= $flags[$flag];
       }
+
       if ($full) {
         $files[$file] = array(
           'mask' => $mask,
-          'ref'  => rtrim($line[3], '.'),
+          'ref'  => $new_hash,
         );
       } else {
         $files[$file] = $mask;
       }
     }
 
     return $files;
   }
 
   public function getAllFiles() {
     $future = $this->buildLocalFuture(array('ls-files -z'));
     return id(new LinesOfALargeExecFuture($future))
       ->setDelimiter("\0");
   }
 
   public function getChangedFiles($since_commit) {
     list($stdout) = $this->execxLocal(
       'diff --raw %s',
       $since_commit);
-    return $this->parseGitStatus($stdout);
+    return $this->parseGitRawDiff($stdout);
   }
 
   public function getBlame($path) {
     list($stdout) = $this->execxLocal(
       'blame --porcelain -w -M %s -- %s',
       $this->getBaseCommit(),
       $path);
 
     // the --porcelain format prints at least one header line per source line,
     // then the source line prefixed by a tab character
     $blame_info = preg_split('/^\t.*\n/m', rtrim($stdout));
 
     // commit info is not repeated in these headers, so cache it
     $revision_data = array();
 
     $blame = array();
     foreach ($blame_info as $line_info) {
       $revision = substr($line_info, 0, 40);
       $data = idx($revision_data, $revision, array());
 
       if (empty($data)) {
         $matches = array();
         if (!preg_match('/^author (.*)$/m', $line_info, $matches)) {
           throw new Exception(
             pht(
               'Unexpected output from %s: no author for commit %s',
               'git blame',
               $revision));
         }
         $data['author'] = $matches[1];
         $data['from_first_commit'] = preg_match('/^boundary$/m', $line_info);
         $revision_data[$revision] = $data;
       }
 
       // Ignore lines predating the git repository (on a boundary commit)
       // rather than blaming them on the oldest diff's unfortunate author
       if (!$data['from_first_commit']) {
         $blame[] = array($data['author'], $revision);
       }
     }
 
     return $blame;
   }
 
   public function getOriginalFileData($path) {
     return $this->getFileDataAtRevision($path, $this->getBaseCommit());
   }
 
   public function getCurrentFileData($path) {
     return $this->getFileDataAtRevision($path, 'HEAD');
   }
 
   private function parseGitTree($stdout) {
     $result = array();
 
     $stdout = trim($stdout);
     if (!strlen($stdout)) {
       return $result;
     }
 
     $lines = explode("\n", $stdout);
     foreach ($lines as $line) {
       $matches = array();
       $ok = preg_match(
         '/^(\d{6}) (blob|tree|commit) ([a-z0-9]{40})[\t](.*)$/',
         $line,
         $matches);
       if (!$ok) {
         throw new Exception(pht('Failed to parse %s output!', 'git ls-tree'));
       }
       $result[$matches[4]] = array(
         'mode' => $matches[1],
         'type' => $matches[2],
         'ref'  => $matches[3],
       );
     }
     return $result;
   }
 
   private function getFileDataAtRevision($path, $revision) {
     // NOTE: We don't want to just "git show {$revision}:{$path}" since if the
     // path was a directory at the given revision we'll get a list of its files
     // and treat it as though it as a file containing a list of other files,
     // which is silly.
 
     list($stdout) = $this->execxLocal(
       'ls-tree %s -- %s',
       $revision,
       $path);
 
     $info = $this->parseGitTree($stdout);
     if (empty($info[$path])) {
       // No such path, or the path is a directory and we executed 'ls-tree dir/'
       // and got a list of its contents back.
       return null;
     }
 
     if ($info[$path]['type'] != 'blob') {
       // Path is or was a directory, not a file.
       return null;
     }
 
     list($stdout) = $this->execxLocal(
       'cat-file blob %s',
        $info[$path]['ref']);
     return $stdout;
   }
 
   /**
    * Returns names of all the branches in the current repository.
    *
    * @return list<dict<string, string>> Dictionary of branch information.
    */
   public function getAllBranches() {
     list($ref_list) = $this->execxLocal(
       'for-each-ref --format=%s refs/heads',
       '%(refname)');
     $refs = explode("\n", rtrim($ref_list));
 
     $current = $this->getBranchName();
     $result = array();
     foreach ($refs as $ref) {
       $branch = $this->getBranchNameFromRef($ref);
       if ($branch) {
         $result[] = array(
           'current' => ($branch === $current),
           'name'    => $branch,
         );
       }
     }
 
     return $result;
   }
 
   public function getWorkingCopyRevision() {
     list($stdout) = $this->execxLocal('rev-parse HEAD');
     return rtrim($stdout, "\n");
   }
 
   public function getUnderlyingWorkingCopyRevision() {
     list($err, $stdout) = $this->execManualLocal('svn find-rev HEAD');
     if (!$err && $stdout) {
       return rtrim($stdout, "\n");
     }
     return $this->getWorkingCopyRevision();
   }
 
   public function isHistoryDefaultImmutable() {
     return false;
   }
 
   public function supportsAmend() {
     return true;
   }
 
   public function supportsCommitRanges() {
     return true;
   }
 
   public function supportsLocalCommits() {
     return true;
   }
 
   public function hasLocalCommit($commit) {
     try {
       if (!$this->getCanonicalRevisionName($commit)) {
         return false;
       }
     } catch (CommandException $exception) {
       return false;
     }
     return true;
   }
 
   public function getAllLocalChanges() {
     $diff = $this->getFullGitDiff($this->getBaseCommit());
     if (!strlen(trim($diff))) {
       return array();
     }
     $parser = new ArcanistDiffParser();
     return $parser->parseDiff($diff);
   }
 
   public function supportsLocalBranchMerge() {
     return true;
   }
 
   public function performLocalBranchMerge($branch, $message) {
     if (!$branch) {
       throw new ArcanistUsageException(
         pht('Under git, you must specify the branch you want to merge.'));
     }
     $err = phutil_passthru(
       '(cd %s && git merge --no-ff -m %s %s)',
       $this->getPath(),
       $message,
       $branch);
 
     if ($err) {
       throw new ArcanistUsageException(pht('Merge failed!'));
     }
   }
 
   public function getFinalizedRevisionMessage() {
     return pht(
       "You may now push this commit upstream, as appropriate (e.g. with ".
       "'%s', or '%s', or by printing and faxing it).",
       'git push',
       'git svn dcommit');
   }
 
   public function getCommitMessage($commit) {
     list($message) = $this->execxLocal(
       'log -n1 --format=%C %s --',
       '%s%n%n%b',
       $commit);
     return $message;
   }
 
   public function loadWorkingCopyDifferentialRevisions(
     ConduitClient $conduit,
     array $query) {
 
     $messages = $this->getGitCommitLog();
     if (!strlen($messages)) {
       return array();
     }
 
     $parser = new ArcanistDiffParser();
     $messages = $parser->parseDiff($messages);
 
     // First, try to find revisions by explicit revision IDs in commit messages.
     $reason_map = array();
     $revision_ids = array();
     foreach ($messages as $message) {
       $object = ArcanistDifferentialCommitMessage::newFromRawCorpus(
         $message->getMetadata('message'));
       if ($object->getRevisionID()) {
         $revision_ids[] = $object->getRevisionID();
         $reason_map[$object->getRevisionID()] = $message->getCommitHash();
       }
     }
 
     if ($revision_ids) {
       $results = $conduit->callMethodSynchronous(
         'differential.query',
         $query + array(
           'ids' => $revision_ids,
         ));
 
       foreach ($results as $key => $result) {
         $hash = substr($reason_map[$result['id']], 0, 16);
         $results[$key]['why'] = pht(
           "Commit message for '%s' has explicit 'Differential Revision'.",
           $hash);
       }
 
       return $results;
     }
 
     // If we didn't succeed, try to find revisions by hash.
     $hashes = array();
     foreach ($this->getLocalCommitInformation() as $commit) {
       $hashes[] = array('gtcm', $commit['commit']);
       $hashes[] = array('gttr', $commit['tree']);
     }
 
     $results = $conduit->callMethodSynchronous(
       'differential.query',
       $query + array(
         'commitHashes' => $hashes,
       ));
 
     foreach ($results as $key => $result) {
       $results[$key]['why'] = pht(
         'A git commit or tree hash in the commit range is already attached '.
         'to the Differential revision.');
     }
 
     return $results;
   }
 
   public function updateWorkingCopy() {
     $this->execxLocal('pull');
     $this->reloadWorkingCopy();
   }
 
   public function getCommitSummary($commit) {
     if ($commit == self::GIT_MAGIC_ROOT_COMMIT) {
       return pht('(The Empty Tree)');
     }
 
     list($summary) = $this->execxLocal(
       'log -n 1 --format=%C %s',
       '%s',
       $commit);
 
     return trim($summary);
   }
 
   public function backoutCommit($commit_hash) {
     $this->execxLocal('revert %s -n --no-edit', $commit_hash);
     $this->reloadWorkingCopy();
     if (!$this->getUncommittedStatus()) {
       throw new ArcanistUsageException(
         pht('%s has already been reverted.', $commit_hash));
     }
   }
 
   public function getBackoutMessage($commit_hash) {
     return pht('This reverts commit %s.', $commit_hash);
   }
 
   public function isGitSubversionRepo() {
     return Filesystem::pathExists($this->getPath('.git/svn'));
   }
 
   public function resolveBaseCommitRule($rule, $source) {
     list($type, $name) = explode(':', $rule, 2);
 
     switch ($type) {
       case 'git':
         $matches = null;
         if (preg_match('/^merge-base\((.+)\)$/', $name, $matches)) {
           list($err, $merge_base) = $this->execManualLocal(
             'merge-base %s HEAD',
             $matches[1]);
           if (!$err) {
             $this->setBaseCommitExplanation(
               pht(
                 "it is the merge-base of '%s' and HEAD, as specified by ".
                 "'%s' in your %s 'base' configuration.",
                 $matches[1],
                 $rule,
                 $source));
             return trim($merge_base);
           }
         } else if (preg_match('/^branch-unique\((.+)\)$/', $name, $matches)) {
           list($err, $merge_base) = $this->execManualLocal(
             'merge-base %s HEAD',
             $matches[1]);
           if ($err) {
             return null;
           }
           $merge_base = trim($merge_base);
 
           list($commits) = $this->execxLocal(
             'log --format=%C %s..HEAD --',
             '%H',
             $merge_base);
           $commits = array_filter(explode("\n", $commits));
 
           if (!$commits) {
             return null;
           }
 
           $commits[] = $merge_base;
 
           $head_branch_count = null;
           $all_branch_names = ipull($this->getAllBranches(), 'name');
           foreach ($commits as $commit) {
             // Ideally, we would use something like "for-each-ref --contains"
             // to get a filtered list of branches ready for script consumption.
             // Instead, try to get predictable output from "branch --contains".
             list($branches) = $this->execxLocal(
               '-c column.ui=never -c color.ui=never branch --contains %s',
               $commit);
             $branches = array_filter(explode("\n", $branches));
 
             // Filter the list, removing the "current" marker (*) and ignoring
             // anything other than known branch names (mainly, any possible
             // "detached HEAD" or "no branch" line).
             foreach ($branches as $key => $branch) {
               $branch = trim($branch, ' *');
               if (in_array($branch, $all_branch_names)) {
                 $branches[$key] = $branch;
               } else {
                 unset($branches[$key]);
               }
             }
 
             if ($head_branch_count === null) {
               // If this is the first commit, it's HEAD. Count how many
               // branches it is on; we want to include commits on the same
               // number of branches. This covers a case where this branch
               // has sub-branches and we're running "arc diff" here again
               // for whatever reason.
               $head_branch_count = count($branches);
             } else if (count($branches) > $head_branch_count) {
               $branches = implode(', ', $branches);
               $this->setBaseCommitExplanation(
                 pht(
                   "it is the first commit between '%s' (the merge-base of ".
                   "'%s' and HEAD) which is also contained by another branch ".
                   "(%s).",
                   $merge_base,
                   $matches[1],
                   $branches));
               return $commit;
             }
           }
         } else {
           list($err) = $this->execManualLocal(
             'cat-file -t %s',
             $name);
           if (!$err) {
             $this->setBaseCommitExplanation(
               pht(
                 "it is specified by '%s' in your %s 'base' configuration.",
                 $rule,
                 $source));
             return $name;
           }
         }
         break;
       case 'arc':
         switch ($name) {
           case 'empty':
             $this->setBaseCommitExplanation(
               pht(
                 "you specified '%s' in your %s 'base' configuration.",
                 $rule,
                 $source));
             return self::GIT_MAGIC_ROOT_COMMIT;
           case 'amended':
             $text = $this->getCommitMessage('HEAD');
             $message = ArcanistDifferentialCommitMessage::newFromRawCorpus(
               $text);
             if ($message->getRevisionID()) {
               $this->setBaseCommitExplanation(
                 pht(
                   "HEAD has been amended with 'Differential Revision:', ".
                   "as specified by '%s' in your %s 'base' configuration.",
                   $rule,
                   $source));
               return 'HEAD^';
             }
             break;
           case 'upstream':
             list($err, $upstream) = $this->execManualLocal(
               'rev-parse --abbrev-ref --symbolic-full-name %s',
               '@{upstream}');
             if (!$err) {
               $upstream = rtrim($upstream);
               list($upstream_merge_base) = $this->execxLocal(
                 'merge-base %s HEAD',
                 $upstream);
               $upstream_merge_base = rtrim($upstream_merge_base);
               $this->setBaseCommitExplanation(
                 pht(
                   "it is the merge-base of the upstream of the current branch ".
                   "and HEAD, and matched the rule '%s' in your %s ".
                   "'base' configuration.",
                   $rule,
                   $source));
               return $upstream_merge_base;
             }
             break;
           case 'this':
             $this->setBaseCommitExplanation(
               pht(
                 "you specified '%s' in your %s 'base' configuration.",
                 $rule,
                 $source));
             return 'HEAD^';
         }
       default:
         return null;
     }
 
     return null;
   }
 
   public function canStashChanges() {
     return true;
   }
 
   public function stashChanges() {
     $this->execxLocal('stash');
     $this->reloadWorkingCopy();
   }
 
   public function unstashChanges() {
     $this->execxLocal('stash pop');
   }
 
   protected function didReloadCommitRange() {
     // After an amend, the symbolic head may resolve to a different commit.
     $this->resolvedHeadCommit = null;
   }
 
 }
diff --git a/src/repository/api/ArcanistRepositoryAPI.php b/src/repository/api/ArcanistRepositoryAPI.php
index 292a7d32..a77a8c90 100644
--- a/src/repository/api/ArcanistRepositoryAPI.php
+++ b/src/repository/api/ArcanistRepositoryAPI.php
@@ -1,660 +1,671 @@
 <?php
 
 /**
  * Interfaces with the VCS in the working copy.
  *
  * @task  status      Path Status
  */
 abstract class ArcanistRepositoryAPI extends Phobject {
 
   const FLAG_MODIFIED     = 1;
   const FLAG_ADDED        = 2;
   const FLAG_DELETED      = 4;
   const FLAG_UNTRACKED    = 8;
   const FLAG_CONFLICT     = 16;
   const FLAG_MISSING      = 32;
   const FLAG_UNSTAGED     = 64;
   const FLAG_UNCOMMITTED  = 128;
+
+  // Occurs in SVN when you have uncommitted changes to a modified external,
+  // or in Git when you have uncommitted or untracked changes in a submodule.
   const FLAG_EXTERNALS    = 256;
 
   // Occurs in SVN when you replace a file with a directory without telling
   // SVN about it.
   const FLAG_OBSTRUCTED   = 512;
 
   // Occurs in SVN when an update was interrupted or failed, e.g. you ^C'd it.
   const FLAG_INCOMPLETE   = 1024;
 
   protected $path;
   protected $diffLinesOfContext = 0x7FFF;
   private $baseCommitExplanation = '???';
   private $configurationManager;
   private $baseCommitArgumentRules;
 
   private $uncommittedStatusCache;
   private $commitRangeStatusCache;
 
   private $symbolicBaseCommit;
   private $resolvedBaseCommit;
 
   abstract public function getSourceControlSystemName();
 
   public function getDiffLinesOfContext() {
     return $this->diffLinesOfContext;
   }
 
   public function setDiffLinesOfContext($lines) {
     $this->diffLinesOfContext = $lines;
     return $this;
   }
 
   public function getWorkingCopyIdentity() {
     return $this->configurationManager->getWorkingCopyIdentity();
   }
 
   public function getConfigurationManager() {
     return $this->configurationManager;
   }
 
   public static function newAPIFromConfigurationManager(
     ArcanistConfigurationManager $configuration_manager) {
 
     $working_copy = $configuration_manager->getWorkingCopyIdentity();
 
     if (!$working_copy) {
       throw new Exception(
         pht(
           'Trying to create a %s without a working copy!',
           __CLASS__));
     }
 
     $root = $working_copy->getProjectRoot();
     switch ($working_copy->getVCSType()) {
       case 'svn':
         $api = new ArcanistSubversionAPI($root);
         break;
       case 'hg':
         $api = new ArcanistMercurialAPI($root);
         break;
       case 'git':
         $api = new ArcanistGitAPI($root);
         break;
       default:
         throw new Exception(
           pht(
             'The current working directory is not part of a working copy for '.
             'a supported version control system (Git, Subversion or '.
             'Mercurial).'));
     }
 
     $api->configurationManager = $configuration_manager;
     return $api;
   }
 
   public function __construct($path) {
     $this->path = $path;
   }
 
   public function getPath($to_file = null) {
     if ($to_file !== null) {
       return $this->path.DIRECTORY_SEPARATOR.
              ltrim($to_file, DIRECTORY_SEPARATOR);
     } else {
       return $this->path.DIRECTORY_SEPARATOR;
     }
   }
 
 
 /* -(  Path Status  )-------------------------------------------------------- */
 
 
   abstract protected function buildUncommittedStatus();
   abstract protected function buildCommitRangeStatus();
 
 
   /**
    * Get a list of uncommitted paths in the working copy that have been changed
    * or are affected by other status effects, like conflicts or untracked
    * files.
    *
    * Convenience methods @{method:getUntrackedChanges},
    * @{method:getUnstagedChanges}, @{method:getUncommittedChanges},
    * @{method:getMergeConflicts}, and @{method:getIncompleteChanges} allow
    * simpler selection of paths in a specific state.
    *
    * This method returns a map of paths to bitmasks with status, using
    * `FLAG_` constants. For example:
    *
    *   array(
    *     'some/uncommitted/file.txt' => ArcanistRepositoryAPI::FLAG_UNSTAGED,
    *   );
    *
    * A file may be in several states. Not all states are possible with all
    * version control systems.
    *
    * @return map<string, bitmask> Map of paths, see above.
    * @task status
    */
   final public function getUncommittedStatus() {
     if ($this->uncommittedStatusCache === null) {
       $status = $this->buildUncommittedStatus();
       ksort($status);
       $this->uncommittedStatusCache = $status;
     }
     return $this->uncommittedStatusCache;
   }
 
 
   /**
    * @task status
    */
   final public function getUntrackedChanges() {
     return $this->getUncommittedPathsWithMask(self::FLAG_UNTRACKED);
   }
 
 
   /**
    * @task status
    */
   final public function getUnstagedChanges() {
     return $this->getUncommittedPathsWithMask(self::FLAG_UNSTAGED);
   }
 
 
   /**
    * @task status
    */
   final public function getUncommittedChanges() {
     return $this->getUncommittedPathsWithMask(self::FLAG_UNCOMMITTED);
   }
 
 
   /**
    * @task status
    */
   final public function getMergeConflicts() {
     return $this->getUncommittedPathsWithMask(self::FLAG_CONFLICT);
   }
 
 
   /**
    * @task status
    */
   final public function getIncompleteChanges() {
     return $this->getUncommittedPathsWithMask(self::FLAG_INCOMPLETE);
   }
 
 
   /**
    * @task status
    */
   final public function getMissingChanges() {
     return $this->getUncommittedPathsWithMask(self::FLAG_MISSING);
   }
 
 
+  /**
+   * @task status
+   */
+  final public function getDirtyExternalChanges() {
+    return $this->getUncommittedPathsWithMask(self::FLAG_EXTERNALS);
+  }
+
+
   /**
    * @task status
    */
   private function getUncommittedPathsWithMask($mask) {
     $match = array();
     foreach ($this->getUncommittedStatus() as $path => $flags) {
       if ($flags & $mask) {
         $match[] = $path;
       }
     }
     return $match;
   }
 
 
   /**
    * Get a list of paths affected by the commits in the current commit range.
    *
    * See @{method:getUncommittedStatus} for a description of the return value.
    *
    * @return map<string, bitmask> Map from paths to status.
    * @task status
    */
   final public function getCommitRangeStatus() {
     if ($this->commitRangeStatusCache === null) {
       $status = $this->buildCommitRangeStatus();
       ksort($status);
       $this->commitRangeStatusCache = $status;
     }
     return $this->commitRangeStatusCache;
   }
 
 
   /**
    * Get a list of paths affected by commits in the current commit range, or
    * uncommitted changes in the working copy. See @{method:getUncommittedStatus}
    * or @{method:getCommitRangeStatus} to retrieve smaller parts of the status.
    *
    * See @{method:getUncommittedStatus} for a description of the return value.
    *
    * @return map<string, bitmask> Map from paths to status.
    * @task status
    */
   final public function getWorkingCopyStatus() {
     $range_status = $this->getCommitRangeStatus();
     $uncommitted_status = $this->getUncommittedStatus();
 
     $result = new PhutilArrayWithDefaultValue($range_status);
     foreach ($uncommitted_status as $path => $mask) {
       $result[$path] |= $mask;
     }
 
     $result = $result->toArray();
     ksort($result);
     return $result;
   }
 
 
   /**
    * Drops caches after changes to the working copy. By default, some queries
    * against the working copy are cached. They
    *
    * @return this
    * @task status
    */
   final public function reloadWorkingCopy() {
     $this->uncommittedStatusCache = null;
     $this->commitRangeStatusCache = null;
 
     $this->didReloadWorkingCopy();
     $this->reloadCommitRange();
 
     return $this;
   }
 
 
   /**
    * Hook for implementations to dirty working copy caches after the working
    * copy has been updated.
    *
    * @return this
    * @task status
    */
   protected function didReloadWorkingCopy() {
     return;
   }
 
 
   /**
    * Fetches the original file data for each path provided.
    *
    * @return map<string, string> Map from path to file data.
    */
   public function getBulkOriginalFileData($paths) {
     $filedata = array();
     foreach ($paths as $path) {
       $filedata[$path] = $this->getOriginalFileData($path);
     }
 
     return $filedata;
   }
 
   /**
    * Fetches the current file data for each path provided.
    *
    * @return map<string, string> Map from path to file data.
    */
   public function getBulkCurrentFileData($paths) {
     $filedata = array();
     foreach ($paths as $path) {
       $filedata[$path] = $this->getCurrentFileData($path);
     }
 
     return $filedata;
   }
 
   /**
    * @return Traversable
    */
   abstract public function getAllFiles();
 
   abstract public function getBlame($path);
 
   abstract public function getRawDiffText($path);
   abstract public function getOriginalFileData($path);
   abstract public function getCurrentFileData($path);
   abstract public function getLocalCommitInformation();
   abstract public function getSourceControlBaseRevision();
   abstract public function getCanonicalRevisionName($string);
   abstract public function getBranchName();
   abstract public function getSourceControlPath();
   abstract public function isHistoryDefaultImmutable();
   abstract public function supportsAmend();
   abstract public function getWorkingCopyRevision();
   abstract public function updateWorkingCopy();
   abstract public function getMetadataPath();
   abstract public function loadWorkingCopyDifferentialRevisions(
     ConduitClient $conduit,
     array $query);
   abstract public function getRemoteURI();
 
 
   public function getUnderlyingWorkingCopyRevision() {
     return $this->getWorkingCopyRevision();
   }
 
   public function getChangedFiles($since_commit) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function getAuthor() {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function addToCommit(array $paths) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   abstract public function supportsLocalCommits();
 
   public function doCommit($message) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function amendCommit($message = null) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function getAllBranches() {
     // TODO: Implement for Mercurial/SVN and make abstract.
     return array();
   }
 
   public function hasLocalCommit($commit) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function getCommitMessage($commit) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function getCommitSummary($commit) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function getAllLocalChanges() {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   abstract public function supportsLocalBranchMerge();
 
   public function performLocalBranchMerge($branch, $message) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function getFinalizedRevisionMessage() {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function execxLocal($pattern /* , ... */) {
     $args = func_get_args();
     return $this->buildLocalFuture($args)->resolvex();
   }
 
   public function execManualLocal($pattern /* , ... */) {
     $args = func_get_args();
     return $this->buildLocalFuture($args)->resolve();
   }
 
   public function execFutureLocal($pattern /* , ... */) {
     $args = func_get_args();
     return $this->buildLocalFuture($args);
   }
 
   abstract protected function buildLocalFuture(array $argv);
 
   public function canStashChanges() {
     return false;
   }
 
   public function stashChanges() {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function unstashChanges() {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
 /* -(  Scratch Files  )------------------------------------------------------ */
 
 
   /**
    * Try to read a scratch file, if it exists and is readable.
    *
    * @param string Scratch file name.
    * @return mixed String for file contents, or false for failure.
    * @task scratch
    */
   public function readScratchFile($path) {
     $full_path = $this->getScratchFilePath($path);
     if (!$full_path) {
       return false;
     }
 
     if (!Filesystem::pathExists($full_path)) {
       return false;
     }
 
     try {
       $result = Filesystem::readFile($full_path);
     } catch (FilesystemException $ex) {
       return false;
     }
 
     return $result;
   }
 
 
   /**
    * Try to write a scratch file, if there's somewhere to put it and we can
    * write there.
    *
    * @param  string Scratch file name to write.
    * @param  string Data to write.
    * @return bool   True on success, false on failure.
    * @task scratch
    */
   public function writeScratchFile($path, $data) {
     $dir = $this->getScratchFilePath('');
     if (!$dir) {
       return false;
     }
 
     if (!Filesystem::pathExists($dir)) {
       try {
         Filesystem::createDirectory($dir);
       } catch (Exception $ex) {
         return false;
       }
     }
 
     try {
       Filesystem::writeFile($this->getScratchFilePath($path), $data);
     } catch (FilesystemException $ex) {
       return false;
     }
 
     return true;
   }
 
 
   /**
    * Try to remove a scratch file.
    *
    * @param   string  Scratch file name to remove.
    * @return  bool    True if the file was removed successfully.
    * @task scratch
    */
   public function removeScratchFile($path) {
     $full_path = $this->getScratchFilePath($path);
     if (!$full_path) {
       return false;
     }
 
     try {
       Filesystem::remove($full_path);
     } catch (FilesystemException $ex) {
       return false;
     }
 
     return true;
   }
 
 
   /**
    * Get a human-readable description of the scratch file location.
    *
    * @param string  Scratch file name.
    * @return mixed  String, or false on failure.
    * @task scratch
    */
   public function getReadableScratchFilePath($path) {
     $full_path = $this->getScratchFilePath($path);
     if ($full_path) {
       return Filesystem::readablePath(
         $full_path,
         $this->getPath());
     } else {
       return false;
     }
   }
 
 
   /**
    * Get the path to a scratch file, if possible.
    *
    * @param string  Scratch file name.
    * @return mixed  File path, or false on failure.
    * @task scratch
    */
   public function getScratchFilePath($path) {
     $new_scratch_path  = Filesystem::resolvePath(
       'arc',
       $this->getMetadataPath());
 
     static $checked = false;
     if (!$checked) {
       $checked = true;
       $old_scratch_path = $this->getPath('.arc');
       // we only want to do the migration once
       // unfortunately, people have checked in .arc directories which
       // means that the old one may get recreated after we delete it
       if (Filesystem::pathExists($old_scratch_path) &&
           !Filesystem::pathExists($new_scratch_path)) {
         Filesystem::createDirectory($new_scratch_path);
         $existing_files = Filesystem::listDirectory($old_scratch_path, true);
         foreach ($existing_files as $file) {
           $new_path = Filesystem::resolvePath($file, $new_scratch_path);
           $old_path = Filesystem::resolvePath($file, $old_scratch_path);
           Filesystem::writeFile(
             $new_path,
             Filesystem::readFile($old_path));
         }
         Filesystem::remove($old_scratch_path);
       }
     }
     return Filesystem::resolvePath($path, $new_scratch_path);
   }
 
 
 /* -(  Base Commits  )------------------------------------------------------- */
 
   abstract public function supportsCommitRanges();
 
   final public function setBaseCommit($symbolic_commit) {
     if (!$this->supportsCommitRanges()) {
       throw new ArcanistCapabilityNotSupportedException($this);
     }
 
     $this->symbolicBaseCommit = $symbolic_commit;
     $this->reloadCommitRange();
     return $this;
   }
 
   public function setHeadCommit($symbolic_commit) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   final public function getBaseCommit() {
     if (!$this->supportsCommitRanges()) {
       throw new ArcanistCapabilityNotSupportedException($this);
     }
 
     if ($this->resolvedBaseCommit === null) {
       $commit = $this->buildBaseCommit($this->symbolicBaseCommit);
       $this->resolvedBaseCommit = $commit;
     }
 
     return $this->resolvedBaseCommit;
   }
 
   public function getHeadCommit() {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   final public function reloadCommitRange() {
     $this->resolvedBaseCommit = null;
     $this->baseCommitExplanation = null;
 
     $this->didReloadCommitRange();
 
     return $this;
   }
 
   protected function didReloadCommitRange() {
     return;
   }
 
   protected function buildBaseCommit($symbolic_commit) {
     throw new ArcanistCapabilityNotSupportedException($this);
   }
 
   public function getBaseCommitExplanation() {
     return $this->baseCommitExplanation;
   }
 
   public function setBaseCommitExplanation($explanation) {
     $this->baseCommitExplanation = $explanation;
     return $this;
   }
 
   public function resolveBaseCommitRule($rule, $source) {
     return null;
   }
 
   public function setBaseCommitArgumentRules($base_commit_argument_rules) {
     $this->baseCommitArgumentRules = $base_commit_argument_rules;
     return $this;
   }
 
   public function getBaseCommitArgumentRules() {
     return $this->baseCommitArgumentRules;
   }
 
   public function resolveBaseCommit() {
     $base_commit_rules = array(
       'runtime' => $this->getBaseCommitArgumentRules(),
       'local'   => '',
       'project' => '',
       'user'    => '',
       'system'  => '',
     );
     $all_sources = $this->configurationManager->getConfigFromAllSources('base');
 
     $base_commit_rules = $all_sources + $base_commit_rules;
 
     $parser = new ArcanistBaseCommitParser($this);
     $commit = $parser->resolveBaseCommit($base_commit_rules);
 
     return $commit;
   }
 
   public function getRepositoryUUID() {
     return null;
   }
 
 }
diff --git a/src/workflow/ArcanistFeatureWorkflow.php b/src/workflow/ArcanistFeatureWorkflow.php
index 4ebbc7cf..f9695e55 100644
--- a/src/workflow/ArcanistFeatureWorkflow.php
+++ b/src/workflow/ArcanistFeatureWorkflow.php
@@ -1,370 +1,370 @@
 <?php
 
 /**
  * Displays user's Git branches or Mercurial bookmarks.
  *
  * @concrete-extensible
  */
 class ArcanistFeatureWorkflow extends ArcanistWorkflow {
 
   private $branches;
 
   public function getWorkflowName() {
     return 'feature';
   }
 
   public function getCommandSynopses() {
     return phutil_console_format(<<<EOTEXT
       **feature** [__options__]
       **feature** __name__ [__start__]
 EOTEXT
       );
   }
 
   public function getCommandHelp() {
     return phutil_console_format(<<<EOTEXT
           Supports: git, hg
           A wrapper on 'git branch' or 'hg bookmark'.
 
           Without __name__, it lists the available branches and their revision
           status.
 
           With __name__, it creates or checks out a branch. If the branch
           __name__ doesn't exist and is in format D123 then the branch of
           revision D123 is checked out. Use __start__ to specify where the new
           branch will start. Use 'arc.feature.start.default' to set the default
           feature start location.
 EOTEXT
       );
   }
 
   public function requiresConduit() {
     return true;
   }
 
   public function requiresRepositoryAPI() {
     return true;
   }
 
   public function requiresAuthentication() {
     return !$this->getArgument('branch');
   }
 
   public function getArguments() {
     return array(
       'view-all' => array(
         'help' => pht('Include closed and abandoned revisions.'),
       ),
       'by-status' => array(
         'help' => pht('Sort branches by status instead of time.'),
       ),
       'output' => array(
         'param' => 'format',
         'support' => array(
           'json',
         ),
         'help' => pht(
           "With '%s', show features in machine-readable JSON format.",
           'json'),
       ),
       '*' => 'branch',
     );
   }
 
   public function getSupportedRevisionControlSystems() {
     return array('git', 'hg');
   }
 
   public function run() {
     $repository_api = $this->getRepositoryAPI();
 
     $names = $this->getArgument('branch');
     if ($names) {
       if (count($names) > 2) {
         throw new ArcanistUsageException(pht('Specify only one branch.'));
       }
       return $this->checkoutBranch($names);
     }
 
     $branches = $repository_api->getAllBranches();
     if (!$branches) {
       throw new ArcanistUsageException(
         pht('No branches in this working copy.'));
     }
 
     $branches = $this->loadCommitInfo($branches);
     $revisions = $this->loadRevisions($branches);
     $this->printBranches($branches, $revisions);
 
     return 0;
   }
 
   private function checkoutBranch(array $names) {
     $api = $this->getRepositoryAPI();
 
     if ($api instanceof ArcanistMercurialAPI) {
       $command = 'update %s';
     } else {
       $command = 'checkout %s';
     }
 
     $err = 1;
 
     $name = $names[0];
     if (isset($names[1])) {
       $start = $names[1];
     } else {
       $start = $this->getConfigFromAnySource('arc.feature.start.default');
     }
 
     $branches = $api->getAllBranches();
     if (in_array($name, ipull($branches, 'name'))) {
       list($err, $stdout, $stderr) = $api->execManualLocal($command, $name);
     }
 
     if ($err) {
       $match = null;
       if (preg_match('/^D(\d+)$/', $name, $match)) {
         try {
           $diff = $this->getConduit()->callMethodSynchronous(
             'differential.querydiffs',
             array(
               'revisionIDs' => array($match[1]),
             ));
           $diff = head($diff);
 
           if ($diff['branch'] != '') {
             $name = $diff['branch'];
             list($err, $stdout, $stderr) = $api->execManualLocal(
               $command,
               $name);
           }
         } catch (ConduitClientException $ex) {}
       }
     }
 
     if ($err) {
       if ($api instanceof ArcanistMercurialAPI) {
         $rev = '';
         if ($start) {
           $rev = csprintf('-r %s', $start);
         }
 
         $exec = $api->execManualLocal('bookmark %C %s', $rev, $name);
 
         if (!$exec[0] && $start) {
           $api->execxLocal('update %s', $name);
         }
       } else {
         $startarg = $start ? csprintf('%s', $start) : '';
         $exec = $api->execManualLocal(
           'checkout --track -b %s %C',
           $name,
           $startarg);
       }
 
       list($err, $stdout, $stderr) = $exec;
     }
 
     echo $stdout;
     fprintf(STDERR, $stderr);
     return $err;
   }
 
   private function loadCommitInfo(array $branches) {
     $repository_api = $this->getRepositoryAPI();
 
     $futures = array();
     foreach ($branches as $branch) {
       if ($repository_api instanceof ArcanistMercurialAPI) {
         $futures[$branch['name']] = $repository_api->execFutureLocal(
           'log -l 1 --template %s -r %s',
           "{node}\1{date|hgdate}\1{p1node}\1{desc|firstline}\1{desc}",
           hgsprintf('%s', $branch['name']));
       } else {
         // NOTE: "-s" is an option deep in git's diff argument parser that
         // doesn't seem to have much documentation and has no long form. It
         // suppresses any diff output.
         $futures[$branch['name']] = $repository_api->execFutureLocal(
           'show -s --format=%C %s --',
           '%H%x01%ct%x01%T%x01%s%x01%s%n%n%b',
           $branch['name']);
       }
     }
 
     $branches = ipull($branches, null, 'name');
 
     $futures = id(new FutureIterator($futures))
       ->limit(16);
     foreach ($futures as $name => $future) {
       list($info) = $future->resolvex();
       list($hash, $epoch, $tree, $desc, $text) = explode("\1", trim($info), 5);
 
       $branch = $branches[$name] + array(
         'hash' => $hash,
         'desc' => $desc,
         'tree' => $tree,
         'epoch' => (int)$epoch,
       );
 
       try {
         $message = ArcanistDifferentialCommitMessage::newFromRawCorpus($text);
         $id = $message->getRevisionID();
 
         $branch['revisionID'] = $id;
       } catch (ArcanistUsageException $ex) {
         // In case of invalid commit message which fails the parsing,
         // do nothing.
         $branch['revisionID'] = null;
       }
 
       $branches[$name] = $branch;
     }
 
     return $branches;
   }
 
   private function loadRevisions(array $branches) {
     $ids = array();
     $hashes = array();
 
     foreach ($branches as $branch) {
       if ($branch['revisionID']) {
         $ids[] = $branch['revisionID'];
       }
       $hashes[] = array('gtcm', $branch['hash']);
       $hashes[] = array('gttr', $branch['tree']);
     }
 
     $calls = array();
 
     if ($ids) {
       $calls[] = $this->getConduit()->callMethod(
         'differential.query',
         array(
           'ids' => $ids,
         ));
     }
 
     if ($hashes) {
       $calls[] = $this->getConduit()->callMethod(
         'differential.query',
         array(
           'commitHashes' => $hashes,
         ));
     }
 
     $results = array();
     foreach (new FutureIterator($calls) as $call) {
       $results[] = $call->resolve();
     }
 
     return array_mergev($results);
   }
 
   private function printBranches(array $branches, array $revisions) {
     $revisions = ipull($revisions, null, 'id');
 
     static $color_map = array(
       'Closed'          => 'cyan',
       'Needs Review'    => 'magenta',
       'Needs Revision'  => 'red',
       'Accepted'        => 'green',
       'No Revision'     => 'blue',
       'Abandoned'       => 'default',
     );
 
     static $ssort_map = array(
       'Closed'          => 1,
       'No Revision'     => 2,
       'Needs Review'    => 3,
       'Needs Revision'  => 4,
       'Accepted'        => 5,
     );
 
     $out = array();
     foreach ($branches as $branch) {
       $revision = idx($revisions, idx($branch, 'revisionID'));
 
       // If we haven't identified a revision by ID, try to identify it by hash.
       if (!$revision) {
         foreach ($revisions as $rev) {
           $hashes = idx($rev, 'hashes', array());
           foreach ($hashes as $hash) {
             if (($hash[0] == 'gtcm' && $hash[1] == $branch['hash']) ||
                 ($hash[0] == 'gttr' && $hash[1] == $branch['tree'])) {
               $revision = $rev;
               break;
             }
           }
         }
       }
 
       if ($revision) {
         $desc = 'D'.$revision['id'].': '.$revision['title'];
         $status = $revision['statusName'];
       } else {
         $desc = $branch['desc'];
         $status = pht('No Revision');
       }
 
       if (!$this->getArgument('view-all') && !$branch['current']) {
         if ($status == 'Closed' || $status == 'Abandoned') {
           continue;
         }
       }
 
       $epoch = $branch['epoch'];
 
       $color = idx($color_map, $status, 'default');
       $ssort = sprintf('%d%012d', idx($ssort_map, $status, 0), $epoch);
 
       $out[] = array(
         'name'      => $branch['name'],
         'current'   => $branch['current'],
         'status'    => $status,
         'desc'      => $desc,
         'revision'  => $revision ? $revision['id'] : null,
         'color'     => $color,
         'esort'     => $epoch,
         'epoch'     => $epoch,
         'ssort'     => $ssort,
       );
     }
 
     $len_name = max(array_map('strlen', ipull($out, 'name'))) + 2;
     $len_status = max(array_map('strlen', ipull($out, 'status'))) + 2;
 
     if ($this->getArgument('by-status')) {
       $out = isort($out, 'ssort');
     } else {
       $out = isort($out, 'esort');
     }
     if ($this->getArgument('output') == 'json') {
       foreach ($out as &$feature) {
         unset($feature['color'], $feature['ssort'], $feature['esort']);
       }
       echo json_encode(ipull($out, null, 'name'))."\n";
     } else {
       $table = id(new PhutilConsoleTable())
         ->setShowHeader(false)
         ->addColumn('current', array('title' => ''))
         ->addColumn('name',    array('title' => pht('Name')))
         ->addColumn('status',  array('title' => pht('Status')))
         ->addColumn('descr',   array('title' => pht('Description')));
 
       foreach ($out as $line) {
         $table->addRow(array(
           'current' => $line['current'] ? '*' : '',
-          'name'    => phutil_console_format('**%s**', $line['name']),
-          'status'  => phutil_console_format(
+          'name'    => tsprintf('**%s**', $line['name']),
+          'status'  => tsprintf(
             "<fg:{$line['color']}>%s</fg>", $line['status']),
           'descr'   => $line['desc'],
         ));
       }
 
       $table->draw();
     }
   }
 
 }
diff --git a/src/workflow/ArcanistListWorkflow.php b/src/workflow/ArcanistListWorkflow.php
index 2cc6a48f..5095ef2e 100644
--- a/src/workflow/ArcanistListWorkflow.php
+++ b/src/workflow/ArcanistListWorkflow.php
@@ -1,109 +1,109 @@
 <?php
 
 /**
  * Lists open revisions in Differential.
  */
 final class ArcanistListWorkflow extends ArcanistWorkflow {
 
   public function getWorkflowName() {
     return 'list';
   }
 
   public function getCommandSynopses() {
     return phutil_console_format(<<<EOTEXT
       **list**
 EOTEXT
       );
   }
 
   public function getCommandHelp() {
     return phutil_console_format(<<<EOTEXT
           Supports: git, svn, hg
           List your open Differential revisions.
 EOTEXT
       );
   }
 
   public function requiresConduit() {
     return true;
   }
 
   public function requiresRepositoryAPI() {
     return true;
   }
 
   public function requiresAuthentication() {
     return true;
   }
 
   public function run() {
     static $color_map = array(
       'Closed'          => 'cyan',
       'Needs Review'    => 'magenta',
       'Needs Revision'  => 'red',
       'Changes Planned' => 'red',
       'Accepted'        => 'green',
       'No Revision'     => 'blue',
       'Abandoned'       => 'default',
     );
 
     $revisions = $this->getConduit()->callMethodSynchronous(
       'differential.query',
       array(
         'authors' => array($this->getUserPHID()),
         'status'  => 'status-open',
       ));
 
     if (!$revisions) {
       echo pht('You have no open Differential revisions.')."\n";
       return 0;
     }
 
     $repository_api = $this->getRepositoryAPI();
 
     $info = array();
     foreach ($revisions as $key => $revision) {
       $revision_path = Filesystem::resolvePath($revision['sourcePath']);
       $current_path  = Filesystem::resolvePath($repository_api->getPath());
       if ($revision_path == $current_path) {
         $info[$key]['exists'] = 1;
       } else {
         $info[$key]['exists'] = 0;
       }
       $info[$key]['sort'] = sprintf(
         '%d%04d%08d',
         $info[$key]['exists'],
         $revision['status'],
         $revision['id']);
       $info[$key]['statusName'] = $revision['statusName'];
       $info[$key]['color'] = idx(
         $color_map, $revision['statusName'], 'default');
     }
 
     $table = id(new PhutilConsoleTable())
       ->setShowHeader(false)
       ->addColumn('exists', array('title' => ''))
       ->addColumn('status', array('title' => pht('Status')))
       ->addColumn('title',  array('title' => pht('Title')));
 
     $info = isort($info, 'sort');
     foreach ($info as $key => $spec) {
       $revision = $revisions[$key];
 
       $table->addRow(array(
-        'exists' => $spec['exists'] ? phutil_console_format('**%s**', '*') : '',
-        'status' => phutil_console_format(
+        'exists' => $spec['exists'] ? tsprintf('**%s**', '*') : '',
+        'status' => tsprintf(
           "<fg:{$spec['color']}>%s</fg>",
           $spec['statusName']),
-        'title'  => phutil_console_format(
+        'title'  => tsprintf(
           '**D%d:** %s',
           $revision['id'],
           $revision['title']),
       ));
     }
 
     $table->draw();
     return 0;
   }
 
 }
diff --git a/src/workflow/ArcanistPhrequentWorkflow.php b/src/workflow/ArcanistPhrequentWorkflow.php
index fd6202c4..3157c8ee 100644
--- a/src/workflow/ArcanistPhrequentWorkflow.php
+++ b/src/workflow/ArcanistPhrequentWorkflow.php
@@ -1,70 +1,70 @@
 <?php
 
 /**
  * Base workflow for Phrequent workflows.
  */
 abstract class ArcanistPhrequentWorkflow extends ArcanistWorkflow {
 
   protected function printCurrentTracking() {
     $conduit = $this->getConduit();
 
     $results = $conduit->callMethodSynchronous(
       'phrequent.tracking',
       array());
     $results = $results['data'];
 
     if (count($results) === 0) {
       echo phutil_console_format(
         "%s\n",
         pht('Not currently tracking time against any object.'));
       return 0;
     }
 
     $phids_to_lookup = array();
     foreach ($results as $result) {
       $phids_to_lookup[] = $result['phid'];
     }
 
     $phid_query = $conduit->callMethodSynchronous(
       'phid.query',
       array(
         'phids' => $phids_to_lookup,
       ));
 
     $phid_map = array();
     foreach ($phids_to_lookup as $lookup) {
       if (array_key_exists($lookup, $phid_query)) {
         $phid_map[$lookup] = $phid_query[$lookup]['fullName'];
       } else {
         $phid_map[$lookup] = pht('Unknown Object');
       }
     }
 
     $table = id(new PhutilConsoleTable())
       ->addColumn('type', array('title' => pht('Status')))
       ->addColumn('time', array('title' => pht('Tracked'), 'align' => 'right'))
       ->addColumn('name', array('title' => pht('Name')))
       ->setBorders(false);
 
     $i = 0;
     foreach ($results as $result) {
       if ($i === 0) {
         $column_type = pht('In Progress');
       } else {
         $column_type = pht('Suspended');
       }
 
       $table->addRow(array(
         'type' => '('.$column_type.')',
-        'time' => phutil_format_relative_time($result['time']),
+        'time' => tsprintf($result['time']),
         'name' => $phid_map[$result['phid']],
       ));
 
       $i++;
     }
 
     $table->draw();
     return 0;
   }
 
 }
diff --git a/src/workflow/ArcanistTasksWorkflow.php b/src/workflow/ArcanistTasksWorkflow.php
index c0d15c3f..95cc7de4 100644
--- a/src/workflow/ArcanistTasksWorkflow.php
+++ b/src/workflow/ArcanistTasksWorkflow.php
@@ -1,211 +1,211 @@
 <?php
 
 /**
  * Displays User Tasks.
  */
 final class ArcanistTasksWorkflow extends ArcanistWorkflow {
 
   private $tasks;
 
   public function getWorkflowName() {
     return 'tasks';
   }
 
   public function getCommandSynopses() {
     return phutil_console_format(<<<EOTEXT
       **tasks** [__options__]
 EOTEXT
       );
   }
 
   public function getCommandHelp() {
     return phutil_console_format(<<<EOTEXT
         View all assigned tasks.
 EOTEXT
       );
   }
 
   public function requiresConduit() {
     return true;
   }
 
   public function requiresRepositoryAPI() {
     return false;
   }
 
   public function requiresAuthentication() {
     return true;
   }
 
   public function getArguments() {
     return array(
       'status' => array(
         'param' => 'task_status',
         'help' => pht('Show tasks that are open or closed, default is open.'),
       ),
       'owner' => array(
         'param' => 'username',
         'paramtype' => 'username',
         'help' => pht(
           'Only show tasks assigned to the given username, '.
           'also accepts %s to show all, default is you.',
           '@all'),
         'conflict' => array(
           'unassigned' => pht('%s suppresses unassigned', '--owner'),
         ),
       ),
       'order' => array(
         'param' => 'task_order',
         'help' => pht(
           'Arrange tasks based on priority, created, or modified, '.
           'default is priority.'),
       ),
       'limit' => array(
         'param' => 'n',
         'paramtype' => 'int',
         'help' => pht('Limit the amount of tasks outputted, default is all.'),
       ),
       'unassigned' => array(
         'help' => pht('Only show tasks that are not assigned (upforgrabs).'),
       ),
     );
   }
 
   public function run() {
     $output = array();
 
     $status     = $this->getArgument('status');
     $owner      = $this->getArgument('owner');
     $order      = $this->getArgument('order');
     $limit      = $this->getArgument('limit');
     $unassigned = $this->getArgument('unassigned');
 
     if ($owner) {
       $owner_phid = $this->findOwnerPhid($owner);
     } else if ($unassigned) {
       $owner_phid = null;
     } else {
       $owner_phid = $this->getUserPHID();
     }
 
     $this->tasks = $this->loadManiphestTasks(
       ($status == 'all' ? 'any' : $status),
       $owner_phid,
       $order,
       $limit);
 
     if (!$this->tasks) {
       echo pht('No tasks found.')."\n";
       return 0;
     }
 
     $table = id(new PhutilConsoleTable())
       ->setShowHeader(false)
       ->addColumn('id', array('title' => pht('ID')))
       ->addColumn('title', array('title' => pht('Title')))
       ->addColumn('priority', array('title' => pht('Priority')))
       ->addColumn('status', array('title' => pht('Status')));
 
     foreach ($this->tasks as $task) {
       $output = array();
 
       // Render the "T123" column.
       $task_id = 'T'.$task['id'];
-      $formatted_task_id = phutil_console_format('**%s**', $task_id);
+      $formatted_task_id = tsprintf('**%s**', $task_id);
       $output['id'] = $formatted_task_id;
 
       // Render the "Title" column.
       $formatted_title = rtrim($task['title']);
       $output['title'] = $formatted_title;
 
       // Render the "Priority" column.
       $web_to_terminal_colors = array(
         'violet'      => 'magenta',
         'indigo'      => 'magenta',
         'orange'      => 'red',
         'sky'         => 'cyan',
         'red'         => 'red',
         'yellow'      => 'yellow',
         'green'       => 'green',
         'blue'        => 'blue',
         'cyan'        => 'cyan',
         'magenta'     => 'magenta',
         'lightred'    => 'red',
         'lightorange' => 'red',
         'lightyellow' => 'yellow',
         'lightgreen'  => 'green',
         'lightblue'   => 'blue',
         'lightsky'    => 'blue',
         'lightindigo' => 'magenta',
         'lightviolet' => 'magenta',
       );
 
       if (isset($task['priorityColor'])) {
         $color = idx($web_to_terminal_colors, $task['priorityColor'], 'white');
       } else {
         $color = 'white';
       }
-      $formatted_priority = phutil_console_format(
+      $formatted_priority = tsprintf(
         "<bg:{$color}> </bg> %s",
         $task['priority']);
       $output['priority'] = $formatted_priority;
 
       // Render the "Status" column.
       if (isset($task['isClosed'])) {
         if ($task['isClosed']) {
           $status_text = $task['statusName'];
           $status_color = 'red';
         } else {
           $status_text = $task['statusName'];
           $status_color = 'green';
         }
-        $formatted_status = phutil_console_format(
+        $formatted_status = tsprintf(
           "<bg:{$status_color}> </bg> %s",
           $status_text);
         $output['status'] = $formatted_status;
       } else {
         $output['status'] = '';
       }
 
       $table->addRow($output);
     }
 
     $table->draw();
   }
 
   private function findOwnerPHID($owner) {
     $conduit = $this->getConduit();
 
     $users = $conduit->callMethodSynchronous(
       'user.query',
       array(
         'usernames' => array($owner),
       ));
 
     if (!$users) {
       return null;
     }
 
     $user = head($users);
     return idx($user, 'phid');
   }
 
   private function loadManiphestTasks($status, $owner_phid, $order, $limit) {
     $conduit = $this->getConduit();
 
     $find_params = array();
     if ($owner_phid !== null) {
       $find_params['ownerPHIDs'] = array($owner_phid);
     }
 
     if ($limit !== false) {
       $find_params['limit'] = $limit;
     }
 
     $find_params['order'] = ($order ? 'order-'.$order : 'order-priority');
     $find_params['status'] = ($status ? 'status-'.$status : 'status-open');
 
     return $conduit->callMethodSynchronous('maniphest.query', $find_params);
   }
 
 }
diff --git a/src/workflow/ArcanistWorkflow.php b/src/workflow/ArcanistWorkflow.php
index 047477e5..54649103 100644
--- a/src/workflow/ArcanistWorkflow.php
+++ b/src/workflow/ArcanistWorkflow.php
@@ -1,2008 +1,2044 @@
 <?php
 
 /**
  * Implements a runnable command, like "arc diff" or "arc help".
  *
  * = Managing Conduit =
  *
  * Workflows have the builtin ability to open a Conduit connection to a
  * Phabricator installation, so methods can be invoked over the API. Workflows
  * may either not need this (e.g., "help"), or may need a Conduit but not
  * authentication (e.g., calling only public APIs), or may need a Conduit and
  * authentication (e.g., "arc diff").
  *
  * To specify that you need an //unauthenticated// conduit, override
  * @{method:requiresConduit} to return ##true##. To specify that you need an
  * //authenticated// conduit, override @{method:requiresAuthentication} to
  * return ##true##. You can also manually invoke @{method:establishConduit}
  * and/or @{method:authenticateConduit} later in a workflow to upgrade it.
  * Once a conduit is open, you can access the client by calling
  * @{method:getConduit}, which allows you to invoke methods. You can get
  * verified information about the user identity by calling @{method:getUserPHID}
  * or @{method:getUserName} after authentication occurs.
  *
  * = Scratch Files =
  *
  * Arcanist workflows can read and write 'scratch files', which are temporary
  * files stored in the project that persist across commands. They can be useful
  * if you want to save some state, or keep a copy of a long message the user
  * entered if something goes wrong.
  *
  *
  * @task  conduit   Conduit
  * @task  scratch   Scratch Files
  * @task  phabrep   Phabricator Repositories
  */
 abstract class ArcanistWorkflow extends Phobject {
 
   const COMMIT_DISABLE = 0;
   const COMMIT_ALLOW = 1;
   const COMMIT_ENABLE = 2;
 
   private $commitMode = self::COMMIT_DISABLE;
 
   private $conduit;
   private $conduitURI;
   private $conduitCredentials;
   private $conduitAuthenticated;
   private $forcedConduitVersion;
   private $conduitTimeout;
 
   private $userPHID;
   private $userName;
   private $repositoryAPI;
   private $configurationManager;
   private $workingCopy;
   private $arguments = array();
   private $passedArguments = array();
   private $command;
 
   private $stashed;
   private $shouldAmend;
 
   private $projectInfo;
   private $repositoryInfo;
   private $repositoryReasons;
 
   private $arcanistConfiguration;
   private $parentWorkflow;
   private $workingDirectory;
   private $repositoryVersion;
 
   private $changeCache = array();
 
 
   public function __construct() {}
 
 
   abstract public function run();
 
   /**
    * Finalizes any cleanup operations that need to occur regardless of
    * whether the command succeeded or failed.
    */
   public function finalize() {
     $this->finalizeWorkingCopy();
   }
 
   /**
    * Return the command used to invoke this workflow from the command like,
    * e.g. "help" for @{class:ArcanistHelpWorkflow}.
    *
    * @return string   The command a user types to invoke this workflow.
    */
   abstract public function getWorkflowName();
 
   /**
    * Return console formatted string with all command synopses.
    *
    * @return string  6-space indented list of available command synopses.
    */
   abstract public function getCommandSynopses();
 
   /**
    * Return console formatted string with command help printed in `arc help`.
    *
    * @return string  10-space indented help to use the command.
    */
   abstract public function getCommandHelp();
 
 
 /* -(  Conduit  )------------------------------------------------------------ */
 
 
   /**
    * Set the URI which the workflow will open a conduit connection to when
    * @{method:establishConduit} is called. Arcanist makes an effort to set
    * this by default for all workflows (by reading ##.arcconfig## and/or the
    * value of ##--conduit-uri##) even if they don't need Conduit, so a workflow
    * can generally upgrade into a conduit workflow later by just calling
    * @{method:establishConduit}.
    *
    * You generally should not need to call this method unless you are
    * specifically overriding the default URI. It is normally sufficient to
    * just invoke @{method:establishConduit}.
    *
    * NOTE: You can not call this after a conduit has been established.
    *
    * @param string  The URI to open a conduit to when @{method:establishConduit}
    *                is called.
    * @return this
    * @task conduit
    */
   final public function setConduitURI($conduit_uri) {
     if ($this->conduit) {
       throw new Exception(
         pht(
           'You can not change the Conduit URI after a '.
           'conduit is already open.'));
     }
     $this->conduitURI = $conduit_uri;
     return $this;
   }
 
   /**
    * Returns the URI the conduit connection within the workflow uses.
    *
    * @return string
    * @task conduit
    */
   final public function getConduitURI() {
     return $this->conduitURI;
   }
 
   /**
    * Open a conduit channel to the server which was previously configured by
    * calling @{method:setConduitURI}. Arcanist will do this automatically if
    * the workflow returns ##true## from @{method:requiresConduit}, or you can
    * later upgrade a workflow and build a conduit by invoking it manually.
    *
    * You must establish a conduit before you can make conduit calls.
    *
    * NOTE: You must call @{method:setConduitURI} before you can call this
    * method.
    *
    * @return this
    * @task conduit
    */
   final public function establishConduit() {
     if ($this->conduit) {
       return $this;
     }
 
     if (!$this->conduitURI) {
       throw new Exception(
         pht(
           'You must specify a Conduit URI with %s before you can '.
           'establish a conduit.',
           'setConduitURI()'));
     }
 
     $this->conduit = new ConduitClient($this->conduitURI);
 
     if ($this->conduitTimeout) {
       $this->conduit->setTimeout($this->conduitTimeout);
     }
 
     $user = $this->getConfigFromAnySource('http.basicauth.user');
     $pass = $this->getConfigFromAnySource('http.basicauth.pass');
     if ($user !== null && $pass !== null) {
       $this->conduit->setBasicAuthCredentials($user, $pass);
     }
 
     return $this;
   }
 
   final public function getConfigFromAnySource($key) {
     return $this->configurationManager->getConfigFromAnySource($key);
   }
 
 
   /**
    * Set credentials which will be used to authenticate against Conduit. These
    * credentials can then be used to establish an authenticated connection to
    * conduit by calling @{method:authenticateConduit}. Arcanist sets some
    * defaults for all workflows regardless of whether or not they return true
    * from @{method:requireAuthentication}, based on the ##~/.arcrc## and
    * ##.arcconf## files if they are present. Thus, you can generally upgrade a
    * workflow which does not require authentication into an authenticated
    * workflow by later invoking @{method:requireAuthentication}. You should not
    * normally need to call this method unless you are specifically overriding
    * the defaults.
    *
    * NOTE: You can not call this method after calling
    * @{method:authenticateConduit}.
    *
    * @param dict  A credential dictionary, see @{method:authenticateConduit}.
    * @return this
    * @task conduit
    */
   final public function setConduitCredentials(array $credentials) {
     if ($this->isConduitAuthenticated()) {
       throw new Exception(
         pht('You may not set new credentials after authenticating conduit.'));
     }
 
     $this->conduitCredentials = $credentials;
     return $this;
   }
 
 
   /**
    * Force arc to identify with a specific Conduit version during the
    * protocol handshake. This is primarily useful for development (especially
    * for sending diffs which bump the client Conduit version), since the client
    * still actually speaks the builtin version of the protocol.
    *
    * Controlled by the --conduit-version flag.
    *
    * @param int Version the client should pretend to be.
    * @return this
    * @task conduit
    */
   final public function forceConduitVersion($version) {
     $this->forcedConduitVersion = $version;
     return $this;
   }
 
 
   /**
    * Get the protocol version the client should identify with.
    *
    * @return int Version the client should claim to be.
    * @task conduit
    */
   final public function getConduitVersion() {
     return nonempty($this->forcedConduitVersion, 6);
   }
 
 
   /**
    * Override the default timeout for Conduit.
    *
    * Controlled by the --conduit-timeout flag.
    *
    * @param float Timeout, in seconds.
    * @return this
    * @task conduit
    */
   final public function setConduitTimeout($timeout) {
     $this->conduitTimeout = $timeout;
     if ($this->conduit) {
       $this->conduit->setConduitTimeout($timeout);
     }
     return $this;
   }
 
 
   /**
    * Open and authenticate a conduit connection to a Phabricator server using
    * provided credentials. Normally, Arcanist does this for you automatically
    * when you return true from @{method:requiresAuthentication}, but you can
    * also upgrade an existing workflow to one with an authenticated conduit
    * by invoking this method manually.
    *
    * You must authenticate the conduit before you can make authenticated conduit
    * calls (almost all calls require authentication).
    *
    * This method uses credentials provided via @{method:setConduitCredentials}
    * to authenticate to the server:
    *
    *    - ##user## (required) The username to authenticate with.
    *    - ##certificate## (required) The Conduit certificate to use.
    *    - ##description## (optional) Description of the invoking command.
    *
    * Successful authentication allows you to call @{method:getUserPHID} and
    * @{method:getUserName}, as well as use the client you access with
    * @{method:getConduit} to make authenticated calls.
    *
    * NOTE: You must call @{method:setConduitURI} and
    * @{method:setConduitCredentials} before you invoke this method.
    *
    * @return this
    * @task conduit
    */
   final public function authenticateConduit() {
     if ($this->isConduitAuthenticated()) {
       return $this;
     }
 
     $this->establishConduit();
     $credentials = $this->conduitCredentials;
 
     try {
       if (!$credentials) {
         throw new Exception(
           pht(
             'Set conduit credentials with %s before authenticating conduit!',
             'setConduitCredentials()'));
       }
 
       // If we have `token`, this server supports the simpler, new-style
       // token-based authentication. Use that instead of all the certificate
       // stuff.
       $token = idx($credentials, 'token');
       if (strlen($token)) {
         $conduit = $this->getConduit();
 
         $conduit->setConduitToken($token);
 
         try {
           $result = $this->getConduit()->callMethodSynchronous(
             'user.whoami',
             array());
 
           $this->userName = $result['userName'];
           $this->userPHID = $result['phid'];
 
           $this->conduitAuthenticated = true;
 
           return;
         } catch (Exception $ex) {
           $conduit->setConduitToken(null);
           throw $ex;
         }
       }
 
       if (empty($credentials['user'])) {
         throw new ConduitClientException(
           'ERR-INVALID-USER',
           pht('Empty user in credentials.'));
       }
       if (empty($credentials['certificate'])) {
         throw new ConduitClientException(
           'ERR-NO-CERTIFICATE',
           pht('Empty certificate in credentials.'));
       }
 
       $description = idx($credentials, 'description', '');
       $user        = $credentials['user'];
       $certificate = $credentials['certificate'];
 
       $connection = $this->getConduit()->callMethodSynchronous(
         'conduit.connect',
         array(
           'client'              => 'arc',
           'clientVersion'       => $this->getConduitVersion(),
           'clientDescription'   => php_uname('n').':'.$description,
           'user'                => $user,
           'certificate'         => $certificate,
           'host'                => $this->conduitURI,
         ));
     } catch (ConduitClientException $ex) {
       if ($ex->getErrorCode() == 'ERR-NO-CERTIFICATE' ||
           $ex->getErrorCode() == 'ERR-INVALID-USER' ||
           $ex->getErrorCode() == 'ERR-INVALID-AUTH') {
         $conduit_uri = $this->conduitURI;
         $message = phutil_console_format(
           "\n%s\n\n    %s\n\n%s\n%s",
           pht('YOU NEED TO __INSTALL A CERTIFICATE__ TO LOGIN TO PHABRICATOR'),
           pht('To do this, run: **%s**', 'arc install-certificate'),
           pht("The server '%s' rejected your request:", $conduit_uri),
           $ex->getMessage());
         throw new ArcanistUsageException($message);
       } else if ($ex->getErrorCode() == 'NEW-ARC-VERSION') {
 
         // Cleverly disguise this as being AWESOME!!!
 
         echo phutil_console_format("**%s**\n\n", pht('New Version Available!'));
         echo phutil_console_wrap($ex->getMessage());
         echo "\n\n";
         echo pht('In most cases, arc can be upgraded automatically.')."\n";
 
         $ok = phutil_console_confirm(
           pht('Upgrade arc now?'),
           $default_no = false);
         if (!$ok) {
           throw $ex;
         }
 
         $root = dirname(phutil_get_library_root('arcanist'));
 
         chdir($root);
         $err = phutil_passthru('%s upgrade', $root.'/bin/arc');
         if (!$err) {
           echo "\n".pht('Try running your arc command again.')."\n";
         }
         exit(1);
       } else {
         throw $ex;
       }
     }
 
     $this->userName = $user;
     $this->userPHID = $connection['userPHID'];
 
     $this->conduitAuthenticated = true;
 
     return $this;
   }
 
   /**
    * @return bool True if conduit is authenticated, false otherwise.
    * @task conduit
    */
   final protected function isConduitAuthenticated() {
     return (bool)$this->conduitAuthenticated;
   }
 
 
   /**
    * Override this to return true if your workflow requires a conduit channel.
    * Arc will build the channel for you before your workflow executes. This
    * implies that you only need an unauthenticated channel; if you need
    * authentication, override @{method:requiresAuthentication}.
    *
    * @return bool True if arc should build a conduit channel before running
    *              the workflow.
    * @task conduit
    */
   public function requiresConduit() {
     return false;
   }
 
 
   /**
    * Override this to return true if your workflow requires an authenticated
    * conduit channel. This implies that it requires a conduit. Arc will build
    * and authenticate the channel for you before the workflow executes.
    *
    * @return bool True if arc should build an authenticated conduit channel
    *              before running the workflow.
    * @task conduit
    */
   public function requiresAuthentication() {
     return false;
   }
 
 
   /**
    * Returns the PHID for the user once they've authenticated via Conduit.
    *
    * @return phid Authenticated user PHID.
    * @task conduit
    */
   final public function getUserPHID() {
     if (!$this->userPHID) {
       $workflow = get_class($this);
       throw new Exception(
         pht(
           "This workflow ('%s') requires authentication, override ".
           "%s to return true.",
           $workflow,
           'requiresAuthentication()'));
     }
     return $this->userPHID;
   }
 
   /**
    * Return the username for the user once they've authenticated via Conduit.
    *
    * @return string Authenticated username.
    * @task conduit
    */
   final public function getUserName() {
     return $this->userName;
   }
 
 
   /**
    * Get the established @{class@libphutil:ConduitClient} in order to make
    * Conduit method calls. Before the client is available it must be connected,
    * either implicitly by making @{method:requireConduit} or
    * @{method:requireAuthentication} return true, or explicitly by calling
    * @{method:establishConduit} or @{method:authenticateConduit}.
    *
    * @return @{class@libphutil:ConduitClient} Live conduit client.
    * @task conduit
    */
   final public function getConduit() {
     if (!$this->conduit) {
       $workflow = get_class($this);
       throw new Exception(
         pht(
           "This workflow ('%s') requires a Conduit, override ".
           "%s to return true.",
           $workflow,
           'requiresConduit()'));
     }
     return $this->conduit;
   }
 
 
   final public function setArcanistConfiguration(
     ArcanistConfiguration $arcanist_configuration) {
 
     $this->arcanistConfiguration = $arcanist_configuration;
     return $this;
   }
 
   final public function getArcanistConfiguration() {
     return $this->arcanistConfiguration;
   }
 
   final public function setConfigurationManager(
     ArcanistConfigurationManager $arcanist_configuration_manager) {
 
     $this->configurationManager = $arcanist_configuration_manager;
     return $this;
   }
 
   final public function getConfigurationManager() {
     return $this->configurationManager;
   }
 
   public function requiresWorkingCopy() {
     return false;
   }
 
   public function desiresWorkingCopy() {
     return false;
   }
 
   public function requiresRepositoryAPI() {
     return false;
   }
 
   public function desiresRepositoryAPI() {
     return false;
   }
 
   final public function setCommand($command) {
     $this->command = $command;
     return $this;
   }
 
   final public function getCommand() {
     return $this->command;
   }
 
   public function getArguments() {
     return array();
   }
 
   final public function setWorkingDirectory($working_directory) {
     $this->workingDirectory = $working_directory;
     return $this;
   }
 
   final public function getWorkingDirectory() {
     return $this->workingDirectory;
   }
 
   final private function setParentWorkflow($parent_workflow) {
     $this->parentWorkflow = $parent_workflow;
     return $this;
   }
 
   final protected function getParentWorkflow() {
     return $this->parentWorkflow;
   }
 
   final public function buildChildWorkflow($command, array $argv) {
     $arc_config = $this->getArcanistConfiguration();
     $workflow = $arc_config->buildWorkflow($command);
     $workflow->setParentWorkflow($this);
     $workflow->setCommand($command);
     $workflow->setConfigurationManager($this->getConfigurationManager());
 
     if ($this->repositoryAPI) {
       $workflow->setRepositoryAPI($this->repositoryAPI);
     }
 
     if ($this->userPHID) {
       $workflow->userPHID = $this->getUserPHID();
       $workflow->userName = $this->getUserName();
     }
 
     if ($this->conduit) {
       $workflow->conduit = $this->conduit;
       $workflow->setConduitCredentials($this->conduitCredentials);
       $workflow->conduitAuthenticated = $this->conduitAuthenticated;
     }
 
     if ($this->workingCopy) {
       $workflow->setWorkingCopy($this->workingCopy);
     }
 
     $workflow->setArcanistConfiguration($arc_config);
 
     $workflow->parseArguments(array_values($argv));
 
     return $workflow;
   }
 
   final public function getArgument($key, $default = null) {
     return idx($this->arguments, $key, $default);
   }
 
   final public function getPassedArguments() {
     return $this->passedArguments;
   }
 
   final public function getCompleteArgumentSpecification() {
     $spec = $this->getArguments();
     $arc_config = $this->getArcanistConfiguration();
     $command = $this->getCommand();
     $spec += $arc_config->getCustomArgumentsForCommand($command);
 
     return $spec;
   }
 
   final public function parseArguments(array $args) {
     $this->passedArguments = $args;
 
     $spec = $this->getCompleteArgumentSpecification();
 
     $dict = array();
 
     $more_key = null;
     if (!empty($spec['*'])) {
       $more_key = $spec['*'];
       unset($spec['*']);
       $dict[$more_key] = array();
     }
 
     $short_to_long_map = array();
     foreach ($spec as $long => $options) {
       if (!empty($options['short'])) {
         $short_to_long_map[$options['short']] = $long;
       }
     }
 
     foreach ($spec as $long => $options) {
       if (!empty($options['repeat'])) {
         $dict[$long] = array();
       }
     }
 
     $more = array();
     $size = count($args);
     for ($ii = 0; $ii < $size; $ii++) {
       $arg = $args[$ii];
       $arg_name = null;
       $arg_key = null;
       if ($arg == '--') {
         $more = array_merge(
           $more,
           array_slice($args, $ii + 1));
         break;
       } else if (!strncmp($arg, '--', 2)) {
         $arg_key = substr($arg, 2);
         $parts = explode('=', $arg_key, 2);
         if (count($parts) == 2) {
           list($arg_key, $val) = $parts;
 
           array_splice($args, $ii, 1, array('--'.$arg_key, $val));
           $size++;
         }
 
         if (!array_key_exists($arg_key, $spec)) {
           $corrected = ArcanistConfiguration::correctArgumentSpelling(
             $arg_key,
             array_keys($spec));
           if (count($corrected) == 1) {
             PhutilConsole::getConsole()->writeErr(
               pht(
                 "(Assuming '%s' is the British spelling of '%s'.)",
                 '--'.$arg_key,
                 '--'.head($corrected))."\n");
             $arg_key = head($corrected);
           } else {
             throw new ArcanistUsageException(
               pht(
                 "Unknown argument '%s'. Try '%s'.",
                 $arg_key,
                 'arc help'));
           }
         }
       } else if (!strncmp($arg, '-', 1)) {
         $arg_key = substr($arg, 1);
         if (empty($short_to_long_map[$arg_key])) {
           throw new ArcanistUsageException(
             pht(
               "Unknown argument '%s'. Try '%s'.",
               $arg_key,
               'arc help'));
         }
         $arg_key = $short_to_long_map[$arg_key];
       } else {
         $more[] = $arg;
         continue;
       }
 
       $options = $spec[$arg_key];
       if (empty($options['param'])) {
         $dict[$arg_key] = true;
       } else {
         if ($ii == $size - 1) {
           throw new ArcanistUsageException(
             pht(
               "Option '%s' requires a parameter.",
               $arg));
         }
         if (!empty($options['repeat'])) {
           $dict[$arg_key][] = $args[$ii + 1];
         } else {
           $dict[$arg_key] = $args[$ii + 1];
         }
         $ii++;
       }
     }
 
     if ($more) {
       if ($more_key) {
         $dict[$more_key] = $more;
       } else {
         $example = reset($more);
         throw new ArcanistUsageException(
           pht(
             "Unrecognized argument '%s'. Try '%s'.",
             $example,
             'arc help'));
       }
     }
 
     foreach ($dict as $key => $value) {
       if (empty($spec[$key]['conflicts'])) {
         continue;
       }
       foreach ($spec[$key]['conflicts'] as $conflict => $more) {
         if (isset($dict[$conflict])) {
           if ($more) {
             $more = ': '.$more;
           } else {
             $more = '.';
           }
           // TODO: We'll always display these as long-form, when the user might
           // have typed them as short form.
           throw new ArcanistUsageException(
             pht(
               "Arguments '%s' and '%s' are mutually exclusive",
               "--{$key}",
               "--{$conflict}").$more);
         }
       }
     }
 
     $this->arguments = $dict;
 
     $this->didParseArguments();
 
     return $this;
   }
 
   protected function didParseArguments() {
     // Override this to customize workflow argument behavior.
   }
 
   final public function getWorkingCopy() {
     $working_copy = $this->getConfigurationManager()->getWorkingCopyIdentity();
     if (!$working_copy) {
       $workflow = get_class($this);
       throw new Exception(
         pht(
           "This workflow ('%s') requires a working copy, override ".
           "%s to return true.",
           $workflow,
           'requiresWorkingCopy()'));
     }
     return $working_copy;
   }
 
   final public function setWorkingCopy(
     ArcanistWorkingCopyIdentity $working_copy) {
     $this->workingCopy = $working_copy;
     return $this;
   }
 
   final public function setRepositoryAPI($api) {
     $this->repositoryAPI = $api;
     return $this;
   }
 
   final public function hasRepositoryAPI() {
     try {
       return (bool)$this->getRepositoryAPI();
     } catch (Exception $ex) {
       return false;
     }
   }
 
   final public function getRepositoryAPI() {
     if (!$this->repositoryAPI) {
       $workflow = get_class($this);
       throw new Exception(
         pht(
           "This workflow ('%s') requires a Repository API, override ".
           "%s to return true.",
           $workflow,
           'requiresRepositoryAPI()'));
     }
     return $this->repositoryAPI;
   }
 
   final protected function shouldRequireCleanUntrackedFiles() {
     return empty($this->arguments['allow-untracked']);
   }
 
   final public function setCommitMode($mode) {
     $this->commitMode = $mode;
     return $this;
   }
 
   final public function finalizeWorkingCopy() {
     if ($this->stashed) {
       $api = $this->getRepositoryAPI();
       $api->unstashChanges();
       echo pht('Restored stashed changes to the working directory.')."\n";
     }
   }
 
   final public function requireCleanWorkingCopy() {
     $api = $this->getRepositoryAPI();
 
     $must_commit = array();
 
     $working_copy_desc = phutil_console_format(
       "  %s: __%s__\n\n",
       pht('Working copy'),
       $api->getPath());
 
     // NOTE: this is a subversion-only concept.
     $incomplete = $api->getIncompleteChanges();
     if ($incomplete) {
       throw new ArcanistUsageException(
         sprintf(
           "%s\n\n%s  %s\n    %s\n\n%s",
           pht(
             "You have incompletely checked out directories in this working ".
             "copy. Fix them before proceeding.'"),
           $working_copy_desc,
           pht('Incomplete directories in working copy:'),
           implode("\n    ", $incomplete),
           pht(
             "You can fix these paths by running '%s' on them.",
             'svn update')));
     }
 
     $conflicts = $api->getMergeConflicts();
     if ($conflicts) {
       throw new ArcanistUsageException(
         sprintf(
           "%s\n\n%s  %s\n    %s",
           pht(
             'You have merge conflicts in this working copy. Resolve merge '.
             'conflicts before proceeding.'),
           $working_copy_desc,
           pht('Conflicts in working copy:'),
           implode("\n    ", $conflicts)));
     }
 
     $missing = $api->getMissingChanges();
     if ($missing) {
       throw new ArcanistUsageException(
         sprintf(
           "%s\n\n%s  %s\n    %s\n",
           pht(
             'You have missing files in this working copy. Revert or formally '.
             'remove them (with `%s`) before proceeding.',
             'svn rm'),
           $working_copy_desc,
           pht('Missing files in working copy:'),
           implode("\n    ", $missing)));
     }
 
+    $externals = $api->getDirtyExternalChanges();
+
+    // TODO: This state can exist in Subversion, but it is currently handled
+    // elsewhere. It should probably be handled here, eventually.
+    if ($api instanceof ArcanistSubversionAPI) {
+      $externals = array();
+    }
+
+    if ($externals) {
+      $message = pht(
+        '%s submodule(s) have uncommitted or untracked changes:',
+        new PhutilNumber(count($externals)));
+
+      $prompt = pht(
+        'Ignore the changes to these %s submodule(s) and continue?',
+        new PhutilNumber(count($externals)));
+
+      $list = id(new PhutilConsoleList())
+        ->setWrap(false)
+        ->addItems($externals);
+
+      id(new PhutilConsoleBlock())
+        ->addParagraph($message)
+        ->addList($list)
+        ->draw();
+
+      $ok = phutil_console_confirm($prompt, $default_no = false);
+      if (!$ok) {
+        throw new ArcanistUserAbortException();
+      }
+    }
+
     $uncommitted = $api->getUncommittedChanges();
     $unstaged = $api->getUnstagedChanges();
 
+    // We already dealt with externals.
+    $unstaged = array_diff($unstaged, $externals);
+
     // We only want files which are purely uncommitted.
     $uncommitted = array_diff($uncommitted, $unstaged);
+    $uncommitted = array_diff($uncommitted, $externals);
 
     $untracked = $api->getUntrackedChanges();
     if (!$this->shouldRequireCleanUntrackedFiles()) {
       $untracked = array();
     }
 
     if ($untracked) {
       echo sprintf(
         "%s\n\n%s",
         pht('You have untracked files in this working copy.'),
         $working_copy_desc);
 
       if ($api instanceof ArcanistGitAPI) {
         $hint = pht(
           '(To ignore these %s change(s), add them to "%s".)',
           new PhutilNumber(count($untracked)),
           '.git/info/exclude');
       } else if ($api instanceof ArcanistSubversionAPI) {
         $hint = pht(
           '(To ignore these %s change(s), add them to "%s".)',
           new PhutilNumber(count($untracked)),
           'svn:ignore');
       } else if ($api instanceof ArcanistMercurialAPI) {
         $hint = pht(
           '(To ignore these %s change(s), add them to "%s".)',
           new PhutilNumber(count($untracked)),
           '.hgignore');
       }
 
       $untracked_list = "    ".implode("\n    ", $untracked);
       echo sprintf(
         "  %s\n  %s\n%s",
         pht('Untracked changes in working copy:'),
         $hint,
         $untracked_list);
 
       $prompt = pht(
         'Ignore these %s untracked file(s) and continue?',
         new PhutilNumber(count($untracked)));
 
       if (!phutil_console_confirm($prompt)) {
         throw new ArcanistUserAbortException();
       }
     }
 
 
     $should_commit = false;
     if ($unstaged || $uncommitted) {
 
       // NOTE: We're running this because it builds a cache and can take a
       // perceptible amount of time to arrive at an answer, but we don't want
       // to pause in the middle of printing the output below.
       $this->getShouldAmend();
 
       echo sprintf(
         "%s\n\n%s",
         pht('You have uncommitted changes in this working copy.'),
         $working_copy_desc);
 
       $lists = array();
 
       if ($unstaged) {
         $unstaged_list = "    ".implode("\n    ", $unstaged);
         $lists[] = sprintf(
           "  %s\n%s",
           pht('Unstaged changes in working copy:'),
           $unstaged_list);
       }
 
       if ($uncommitted) {
         $uncommitted_list = "    ".implode("\n    ", $uncommitted);
         $lists[] = sprintf(
           "%s\n%s",
           pht('Uncommitted changes in working copy:'),
           $uncommitted_list);
       }
 
       echo implode("\n\n", $lists)."\n";
 
       $all_uncommitted = array_merge($unstaged, $uncommitted);
       if ($this->askForAdd($all_uncommitted)) {
         if ($unstaged) {
           $api->addToCommit($unstaged);
         }
         $should_commit = true;
       } else {
         $permit_autostash = $this->getConfigFromAnySource(
           'arc.autostash',
           false);
         if ($permit_autostash && $api->canStashChanges()) {
            echo pht(
             'Stashing uncommitted changes. (You can restore them with `%s`).',
             'git stash pop')."\n";
           $api->stashChanges();
           $this->stashed = true;
         } else {
           throw new ArcanistUsageException(
             pht(
               'You can not continue with uncommitted changes. '.
               'Commit or discard them before proceeding.'));
         }
       }
     }
 
     if ($should_commit) {
       if ($this->getShouldAmend()) {
         $commit = head($api->getLocalCommitInformation());
         $api->amendCommit($commit['message']);
       } else if ($api->supportsLocalCommits()) {
         $template = sprintf(
           "\n\n# %s\n#\n# %s\n#\n",
           pht('Enter a commit message.'),
           pht('Changes:'));
 
         $paths = array_merge($uncommitted, $unstaged);
         $paths = array_unique($paths);
         sort($paths);
 
         foreach ($paths as $path) {
           $template .= "#     ".$path."\n";
         }
 
         $commit_message = $this->newInteractiveEditor($template)
           ->setName(pht('commit-message'))
           ->editInteractively();
 
         if ($commit_message === $template) {
           throw new ArcanistUsageException(
             pht('You must provide a commit message.'));
         }
 
         $commit_message = ArcanistCommentRemover::removeComments(
           $commit_message);
 
         if (!strlen($commit_message)) {
           throw new ArcanistUsageException(
             pht('You must provide a nonempty commit message.'));
         }
 
         $api->doCommit($commit_message);
       }
     }
   }
 
   private function getShouldAmend() {
     if ($this->shouldAmend === null) {
       $this->shouldAmend = $this->calculateShouldAmend();
     }
     return $this->shouldAmend;
   }
 
   private function calculateShouldAmend() {
     $api = $this->getRepositoryAPI();
 
     if ($this->isHistoryImmutable() || !$api->supportsAmend()) {
       return false;
     }
 
     $commits = $api->getLocalCommitInformation();
     if (!$commits) {
       return false;
     }
 
     $commit = reset($commits);
     $message = ArcanistDifferentialCommitMessage::newFromRawCorpus(
       $commit['message']);
 
     if ($message->getGitSVNBaseRevision()) {
       return false;
     }
 
     if ($api->getAuthor() != $commit['author']) {
       return false;
     }
 
     if ($message->getRevisionID() && $this->getArgument('create')) {
       return false;
     }
 
     // TODO: Check commits since tracking branch. If empty then return false.
 
     // Don't amend the current commit if it has already been published.
     $repository = $this->loadProjectRepository();
     if ($repository) {
       $callsign = $repository['callsign'];
       $commit_name = 'r'.$callsign.$commit['commit'];
       $result = $this->getConduit()->callMethodSynchronous(
         'diffusion.querycommits',
         array('names' => array($commit_name)));
       $known_commit = idx($result['identifierMap'], $commit_name);
       if ($known_commit) {
         return false;
       }
     }
 
     if (!$message->getRevisionID()) {
       return true;
     }
 
     $in_working_copy = $api->loadWorkingCopyDifferentialRevisions(
       $this->getConduit(),
       array(
         'authors' => array($this->getUserPHID()),
         'status' => 'status-open',
       ));
     if ($in_working_copy) {
       return true;
     }
 
     return false;
   }
 
   private function askForAdd(array $files) {
     if ($this->commitMode == self::COMMIT_DISABLE) {
       return false;
     }
     if ($this->commitMode == self::COMMIT_ENABLE) {
       return true;
     }
     $prompt = $this->getAskForAddPrompt($files);
     return phutil_console_confirm($prompt);
   }
 
   private function getAskForAddPrompt(array $files) {
     if ($this->getShouldAmend()) {
       $prompt = pht(
         'Do you want to amend these %s change(s) to the current commit?',
         new PhutilNumber(count($files)));
     } else {
       $prompt = pht(
         'Do you want to create a new commit with these %s change(s)?',
         new PhutilNumber(count($files)));
     }
     return $prompt;
   }
 
   final protected function loadDiffBundleFromConduit(
     ConduitClient $conduit,
     $diff_id) {
 
     return $this->loadBundleFromConduit(
       $conduit,
       array(
       'ids' => array($diff_id),
     ));
   }
 
   final protected function loadRevisionBundleFromConduit(
     ConduitClient $conduit,
     $revision_id) {
 
     return $this->loadBundleFromConduit(
       $conduit,
       array(
       'revisionIDs' => array($revision_id),
     ));
   }
 
   final private function loadBundleFromConduit(
     ConduitClient $conduit,
     $params) {
 
     $future = $conduit->callMethod('differential.querydiffs', $params);
     $diff = head($future->resolve());
 
     $changes = array();
     foreach ($diff['changes'] as $changedict) {
       $changes[] = ArcanistDiffChange::newFromDictionary($changedict);
     }
     $bundle = ArcanistBundle::newFromChanges($changes);
     $bundle->setConduit($conduit);
     // since the conduit method has changes, assume that these fields
     // could be unset
     $bundle->setBaseRevision(idx($diff, 'sourceControlBaseRevision'));
     $bundle->setRevisionID(idx($diff, 'revisionID'));
     $bundle->setAuthorName(idx($diff, 'authorName'));
     $bundle->setAuthorEmail(idx($diff, 'authorEmail'));
     return $bundle;
   }
 
   /**
    * Return a list of lines changed by the current diff, or ##null## if the
    * change list is meaningless (for example, because the path is a directory
    * or binary file).
    *
    * @param string      Path within the repository.
    * @param string      Change selection mode (see ArcanistDiffHunk).
    * @return list|null  List of changed line numbers, or null to indicate that
    *                    the path is not a line-oriented text file.
    */
   final protected function getChangedLines($path, $mode) {
     $repository_api = $this->getRepositoryAPI();
     $full_path = $repository_api->getPath($path);
     if (is_dir($full_path)) {
       return null;
     }
 
     if (!file_exists($full_path)) {
       return null;
     }
 
     $change = $this->getChange($path);
 
     if ($change->getFileType() !== ArcanistDiffChangeType::FILE_TEXT) {
       return null;
     }
 
     $lines = $change->getChangedLines($mode);
     return array_keys($lines);
   }
 
   final protected function getChange($path) {
     $repository_api = $this->getRepositoryAPI();
 
     // TODO: Very gross
     $is_git = ($repository_api instanceof ArcanistGitAPI);
     $is_hg = ($repository_api instanceof ArcanistMercurialAPI);
     $is_svn = ($repository_api instanceof ArcanistSubversionAPI);
 
     if ($is_svn) {
       // NOTE: In SVN, we don't currently support a "get all local changes"
       // operation, so special case it.
       if (empty($this->changeCache[$path])) {
         $diff = $repository_api->getRawDiffText($path);
         $parser = $this->newDiffParser();
         $changes = $parser->parseDiff($diff);
         if (count($changes) != 1) {
           throw new Exception(pht('Expected exactly one change.'));
         }
         $this->changeCache[$path] = reset($changes);
       }
     } else if ($is_git || $is_hg) {
       if (empty($this->changeCache)) {
         $changes = $repository_api->getAllLocalChanges();
         foreach ($changes as $change) {
           $this->changeCache[$change->getCurrentPath()] = $change;
         }
       }
     } else {
       throw new Exception(pht('Missing VCS support.'));
     }
 
     if (empty($this->changeCache[$path])) {
       if ($is_git || $is_hg) {
         // This can legitimately occur under git/hg if you make a change,
         // "git/hg commit" it, and then revert the change in the working copy
         // and run "arc lint".
         $change = new ArcanistDiffChange();
         $change->setCurrentPath($path);
         return $change;
       } else {
         throw new Exception(
           pht(
             "Trying to get change for unchanged path '%s'!",
             $path));
       }
     }
 
     return $this->changeCache[$path];
   }
 
   final public function willRunWorkflow() {
     $spec = $this->getCompleteArgumentSpecification();
     foreach ($this->arguments as $arg => $value) {
       if (empty($spec[$arg])) {
         continue;
       }
       $options = $spec[$arg];
       if (!empty($options['supports'])) {
         $system_name = $this->getRepositoryAPI()->getSourceControlSystemName();
         if (!in_array($system_name, $options['supports'])) {
           $extended_info = null;
           if (!empty($options['nosupport'][$system_name])) {
             $extended_info = ' '.$options['nosupport'][$system_name];
           }
           throw new ArcanistUsageException(
             pht(
               "Option '%s' is not supported under %s.",
               "--{$arg}",
               $system_name).
             $extended_info);
         }
       }
     }
   }
 
   final protected function normalizeRevisionID($revision_id) {
     return preg_replace('/^D/i', '', $revision_id);
   }
 
   protected function shouldShellComplete() {
     return true;
   }
 
   protected function getShellCompletions(array $argv) {
     return array();
   }
 
   public function getSupportedRevisionControlSystems() {
     return array('git', 'hg', 'svn');
   }
 
   final protected function getPassthruArgumentsAsMap($command) {
     $map = array();
     foreach ($this->getCompleteArgumentSpecification() as $key => $spec) {
       if (!empty($spec['passthru'][$command])) {
         if (isset($this->arguments[$key])) {
           $map[$key] = $this->arguments[$key];
         }
       }
     }
     return $map;
   }
 
   final protected function getPassthruArgumentsAsArgv($command) {
     $spec = $this->getCompleteArgumentSpecification();
     $map = $this->getPassthruArgumentsAsMap($command);
     $argv = array();
     foreach ($map as $key => $value) {
       $argv[] = '--'.$key;
       if (!empty($spec[$key]['param'])) {
         $argv[] = $value;
       }
     }
     return $argv;
   }
 
   /**
    * Write a message to stderr so that '--json' flags or stdout which is meant
    * to be piped somewhere aren't disrupted.
    *
    * @param string  Message to write to stderr.
    * @return void
    */
   final protected function writeStatusMessage($msg) {
     fwrite(STDERR, $msg);
   }
 
   final protected function writeInfo($title, $message) {
     $this->writeStatusMessage(
       phutil_console_format(
         "<bg:blue>** %s **</bg> %s\n",
         $title,
         $message));
   }
 
   final protected function writeWarn($title, $message) {
     $this->writeStatusMessage(
       phutil_console_format(
         "<bg:yellow>** %s **</bg> %s\n",
         $title,
         $message));
   }
 
   final protected function writeOkay($title, $message) {
     $this->writeStatusMessage(
       phutil_console_format(
         "<bg:green>** %s **</bg> %s\n",
         $title,
         $message));
   }
 
   final protected function isHistoryImmutable() {
     $repository_api = $this->getRepositoryAPI();
 
     $config = $this->getConfigFromAnySource('history.immutable');
     if ($config !== null) {
       return $config;
     }
 
     return $repository_api->isHistoryDefaultImmutable();
   }
 
   /**
    * Workflows like 'lint' and 'unit' operate on a list of working copy paths.
    * The user can either specify the paths explicitly ("a.js b.php"), or by
    * specifying a revision ("--rev a3f10f1f") to select all paths modified
    * since that revision, or by omitting both and letting arc choose the
    * default relative revision.
    *
    * This method takes the user's selections and returns the paths that the
    * workflow should act upon.
    *
    * @param   list          List of explicitly provided paths.
    * @param   string|null   Revision name, if provided.
    * @param   mask          Mask of ArcanistRepositoryAPI flags to exclude.
    *                        Defaults to ArcanistRepositoryAPI::FLAG_UNTRACKED.
    * @return  list          List of paths the workflow should act on.
    */
   final protected function selectPathsForWorkflow(
     array $paths,
     $rev,
     $omit_mask = null) {
 
     if ($omit_mask === null) {
       $omit_mask = ArcanistRepositoryAPI::FLAG_UNTRACKED;
     }
 
     if ($paths) {
       $working_copy = $this->getWorkingCopy();
       foreach ($paths as $key => $path) {
         $full_path = Filesystem::resolvePath($path);
         if (!Filesystem::pathExists($full_path)) {
           throw new ArcanistUsageException(
             pht(
               "Path '%s' does not exist!",
               $path));
         }
         $relative_path = Filesystem::readablePath(
           $full_path,
           $working_copy->getProjectRoot());
         $paths[$key] = $relative_path;
       }
     } else {
       $repository_api = $this->getRepositoryAPI();
 
       if ($rev) {
         $this->parseBaseCommitArgument(array($rev));
       }
 
       $paths = $repository_api->getWorkingCopyStatus();
       foreach ($paths as $path => $flags) {
         if ($flags & $omit_mask) {
           unset($paths[$path]);
         }
       }
       $paths = array_keys($paths);
     }
 
     return array_values($paths);
   }
 
   final protected function renderRevisionList(array $revisions) {
     $list = array();
     foreach ($revisions as $revision) {
       $list[] = '     - D'.$revision['id'].': '.$revision['title']."\n";
     }
     return implode('', $list);
   }
 
 
 /* -(  Scratch Files  )------------------------------------------------------ */
 
 
   /**
    * Try to read a scratch file, if it exists and is readable.
    *
    * @param string Scratch file name.
    * @return mixed String for file contents, or false for failure.
    * @task scratch
    */
   final protected function readScratchFile($path) {
     if (!$this->repositoryAPI) {
       return false;
     }
     return $this->getRepositoryAPI()->readScratchFile($path);
   }
 
 
   /**
    * Try to read a scratch JSON file, if it exists and is readable.
    *
    * @param string Scratch file name.
    * @return array Empty array for failure.
    * @task scratch
    */
   final protected function readScratchJSONFile($path) {
     $file = $this->readScratchFile($path);
     if (!$file) {
       return array();
     }
     return phutil_json_decode($file);
   }
 
 
   /**
    * Try to write a scratch file, if there's somewhere to put it and we can
    * write there.
    *
    * @param  string Scratch file name to write.
    * @param  string Data to write.
    * @return bool   True on success, false on failure.
    * @task scratch
    */
   final protected function writeScratchFile($path, $data) {
     if (!$this->repositoryAPI) {
       return false;
     }
     return $this->getRepositoryAPI()->writeScratchFile($path, $data);
   }
 
 
   /**
    * Try to write a scratch JSON file, if there's somewhere to put it and we can
    * write there.
    *
    * @param  string Scratch file name to write.
    * @param  array Data to write.
    * @return bool   True on success, false on failure.
    * @task scratch
    */
   final protected function writeScratchJSONFile($path, array $data) {
     return $this->writeScratchFile($path, json_encode($data));
   }
 
 
   /**
    * Try to remove a scratch file.
    *
    * @param   string  Scratch file name to remove.
    * @return  bool    True if the file was removed successfully.
    * @task scratch
    */
   final protected function removeScratchFile($path) {
     if (!$this->repositoryAPI) {
       return false;
     }
     return $this->getRepositoryAPI()->removeScratchFile($path);
   }
 
 
   /**
    * Get a human-readable description of the scratch file location.
    *
    * @param string  Scratch file name.
    * @return mixed  String, or false on failure.
    * @task scratch
    */
   final protected function getReadableScratchFilePath($path) {
     if (!$this->repositoryAPI) {
       return false;
     }
     return $this->getRepositoryAPI()->getReadableScratchFilePath($path);
   }
 
 
   /**
    * Get the path to a scratch file, if possible.
    *
    * @param string  Scratch file name.
    * @return mixed  File path, or false on failure.
    * @task scratch
    */
   final protected function getScratchFilePath($path) {
     if (!$this->repositoryAPI) {
       return false;
     }
     return $this->getRepositoryAPI()->getScratchFilePath($path);
   }
 
   final protected function getRepositoryEncoding() {
     return nonempty(
       idx($this->loadProjectRepository(), 'encoding'),
       'UTF-8');
   }
 
   final protected function loadProjectRepository() {
     list($info, $reasons) = $this->loadRepositoryInformation();
     return coalesce($info, array());
   }
 
   final protected function newInteractiveEditor($text) {
     $editor = new PhutilInteractiveEditor($text);
 
     $preferred = $this->getConfigFromAnySource('editor');
     if ($preferred) {
       $editor->setPreferredEditor($preferred);
     }
 
     return $editor;
   }
 
   final protected function newDiffParser() {
     $parser = new ArcanistDiffParser();
     if ($this->repositoryAPI) {
       $parser->setRepositoryAPI($this->getRepositoryAPI());
     }
     $parser->setWriteDiffOnFailure(true);
     return $parser;
   }
 
   final protected function resolveCall(ConduitFuture $method, $timeout = null) {
     try {
       return $method->resolve($timeout);
     } catch (ConduitClientException $ex) {
       if ($ex->getErrorCode() == 'ERR-CONDUIT-CALL') {
         echo phutil_console_wrap(
           pht(
             'This feature requires a newer version of Phabricator. Please '.
             'update it using these instructions: %s',
             'https://secure.phabricator.com/book/phabricator/article/'.
               'upgrading/')."\n\n");
       }
       throw $ex;
     }
   }
 
   final protected function dispatchEvent($type, array $data) {
     $data += array(
       'workflow' => $this,
     );
 
     $event = new PhutilEvent($type, $data);
     PhutilEventEngine::dispatchEvent($event);
 
     return $event;
   }
 
   final public function parseBaseCommitArgument(array $argv) {
     if (!count($argv)) {
       return;
     }
 
     $api = $this->getRepositoryAPI();
     if (!$api->supportsCommitRanges()) {
       throw new ArcanistUsageException(
         pht('This version control system does not support commit ranges.'));
     }
 
     if (count($argv) > 1) {
       throw new ArcanistUsageException(
         pht(
           'Specify exactly one base commit. The end of the commit range is '.
           'always the working copy state.'));
     }
 
     $api->setBaseCommit(head($argv));
 
     return $this;
   }
 
   final protected function getRepositoryVersion() {
     if (!$this->repositoryVersion) {
       $api = $this->getRepositoryAPI();
       $commit = $api->getSourceControlBaseRevision();
       $versions = array('' => $commit);
       foreach ($api->getChangedFiles($commit) as $path => $mask) {
         $versions[$path] = (Filesystem::pathExists($path)
           ? md5_file($path)
           : '');
       }
       $this->repositoryVersion = md5(json_encode($versions));
     }
     return $this->repositoryVersion;
   }
 
 
 /* -(  Phabricator Repositories  )------------------------------------------- */
 
 
   /**
    * Get the PHID of the Phabricator repository this working copy corresponds
    * to. Returns `null` if no repository can be identified.
    *
    * @return phid|null  Repository PHID, or null if no repository can be
    *                    identified.
    *
    * @task phabrep
    */
   final protected function getRepositoryPHID() {
     return idx($this->getRepositoryInformation(), 'phid');
   }
 
 
   /**
    * Get the callsign of the Phabricator repository this working copy
    * corresponds to. Returns `null` if no repository can be identified.
    *
    * @return string|null  Repository callsign, or null if no repository can be
    *                      identified.
    *
    * @task phabrep
    */
   final protected function getRepositoryCallsign() {
     return idx($this->getRepositoryInformation(), 'callsign');
   }
 
 
   /**
    * Get the URI of the Phabricator repository this working copy
    * corresponds to. Returns `null` if no repository can be identified.
    *
    * @return string|null  Repository URI, or null if no repository can be
    *                      identified.
    *
    * @task phabrep
    */
   final protected function getRepositoryURI() {
     return idx($this->getRepositoryInformation(), 'uri');
   }
 
 
   final protected function getRepositoryStagingConfiguration() {
     return idx($this->getRepositoryInformation(), 'staging');
   }
 
 
   /**
    * Get human-readable reasoning explaining how `arc` evaluated which
    * Phabricator repository corresponds to this working copy. Used by
    * `arc which` to explain the process to users.
    *
    * @return list<string> Human-readable explanation of the repository
    *                      association process.
    *
    * @task phabrep
    */
   final protected function getRepositoryReasons() {
     $this->getRepositoryInformation();
     return $this->repositoryReasons;
   }
 
 
   /**
    * @task phabrep
    */
   private function getRepositoryInformation() {
     if ($this->repositoryInfo === null) {
       list($info, $reasons) = $this->loadRepositoryInformation();
       $this->repositoryInfo = nonempty($info, array());
       $this->repositoryReasons = $reasons;
     }
 
     return $this->repositoryInfo;
   }
 
 
   /**
    * @task phabrep
    */
   private function loadRepositoryInformation() {
     list($query, $reasons) = $this->getRepositoryQuery();
     if (!$query) {
       return array(null, $reasons);
     }
 
     try {
       $results = $this->getConduit()->callMethodSynchronous(
         'repository.query',
         $query);
     } catch (ConduitClientException $ex) {
       if ($ex->getErrorCode() == 'ERR-CONDUIT-CALL') {
         $reasons[] = pht(
           'This version of Arcanist is more recent than the version of '.
           'Phabricator you are connecting to: the Phabricator install is '.
           'out of date and does not have support for identifying '.
           'repositories by callsign or URI. Update Phabricator to enable '.
           'these features.');
         return array(null, $reasons);
       }
       throw $ex;
     }
 
     $result = null;
     if (!$results) {
       $reasons[] = pht(
         'No repositories matched the query. Check that your configuration '.
         'is correct, or use "%s" to select a repository explicitly.',
         'repository.callsign');
     } else if (count($results) > 1) {
       $reasons[] = pht(
         'Multiple repostories (%s) matched the query. You can use the '.
         '"%s" configuration to select the one you want.',
         implode(', ', ipull($results, 'callsign')),
         'repository.callsign');
     } else {
       $result = head($results);
       $reasons[] = pht('Found a unique matching repository.');
     }
 
     return array($result, $reasons);
   }
 
 
   /**
    * @task phabrep
    */
   private function getRepositoryQuery() {
     $reasons = array();
 
     $callsign = $this->getConfigFromAnySource('repository.callsign');
     if ($callsign) {
       $query = array(
         'callsigns' => array($callsign),
       );
       $reasons[] = pht(
         'Configuration value "%s" is set to "%s".',
         'repository.callsign',
         $callsign);
       return array($query, $reasons);
     } else {
       $reasons[] = pht(
         'Configuration value "%s" is empty.',
         'repository.callsign');
     }
 
     $uuid = $this->getRepositoryAPI()->getRepositoryUUID();
     if ($uuid !== null) {
       $query = array(
         'uuids' => array($uuid),
       );
       $reasons[] = pht(
         'The UUID for this working copy is "%s".',
         $uuid);
       return array($query, $reasons);
     } else {
       $reasons[] = pht(
         'This repository has no VCS UUID (this is normal for git/hg).');
     }
 
     $remote_uri = $this->getRepositoryAPI()->getRemoteURI();
     if ($remote_uri !== null) {
       $query = array(
         'remoteURIs' => array($remote_uri),
       );
       $reasons[] = pht(
         'The remote URI for this working copy is "%s".',
         $remote_uri);
       return array($query, $reasons);
     } else {
       $reasons[] = pht(
         'Unable to determine the remote URI for this repository.');
     }
 
     return array(null, $reasons);
   }
 
 
   /**
    * Build a new lint engine for the current working copy.
    *
    * Optionally, you can pass an explicit engine class name to build an engine
    * of a particular class. Normally this is used to implement an `--engine`
    * flag from the CLI.
    *
    * @param string Optional explicit engine class name.
    * @return ArcanistLintEngine Constructed engine.
    */
   protected function newLintEngine($engine_class = null) {
     $working_copy = $this->getWorkingCopy();
     $config = $this->getConfigurationManager();
 
     if (!$engine_class) {
       $engine_class = $config->getConfigFromAnySource('lint.engine');
     }
 
     if (!$engine_class) {
       if (Filesystem::pathExists($working_copy->getProjectPath('.arclint'))) {
         $engine_class = 'ArcanistConfigurationDrivenLintEngine';
       }
     }
 
     if (!$engine_class) {
       throw new ArcanistNoEngineException(
         pht(
           "No lint engine is configured for this project. Create an '%s' ".
           "file, or configure an advanced engine with '%s' in '%s'.",
           '.arclint',
           'lint.engine',
           '.arcconfig'));
     }
 
     $base_class = 'ArcanistLintEngine';
     if (!class_exists($engine_class) ||
         !is_subclass_of($engine_class, $base_class)) {
       throw new ArcanistUsageException(
         pht(
           'Configured lint engine "%s" is not a subclass of "%s", but must be.',
           $engine_class,
           $base_class));
     }
 
     $engine = newv($engine_class, array())
       ->setWorkingCopy($working_copy)
       ->setConfigurationManager($config);
 
     return $engine;
   }
 
   /**
    * Build a new unit test engine for the current working copy.
    *
    * Optionally, you can pass an explicit engine class name to build an engine
    * of a particular class. Normally this is used to implement an `--engine`
    * flag from the CLI.
    *
    * @param string Optional explicit engine class name.
    * @return ArcanistUnitTestEngine Constructed engine.
    */
   protected function newUnitTestEngine($engine_class = null) {
     $working_copy = $this->getWorkingCopy();
     $config = $this->getConfigurationManager();
 
     if (!$engine_class) {
       $engine_class = $config->getConfigFromAnySource('unit.engine');
     }
 
     if (!$engine_class) {
       if (Filesystem::pathExists($working_copy->getProjectPath('.arcunit'))) {
         $engine_class = 'ArcanistConfigurationDrivenUnitTestEngine';
       }
     }
 
     if (!$engine_class) {
       throw new ArcanistNoEngineException(
         pht(
           "No unit test engine is configured for this project. Create an ".
           "'%s' file, or configure an advanced engine with '%s' in '%s'.",
           '.arcunit',
           'unit.engine',
           '.arcconfig'));
     }
 
     $base_class = 'ArcanistUnitTestEngine';
     if (!class_exists($engine_class) ||
         !is_subclass_of($engine_class, $base_class)) {
       throw new ArcanistUsageException(
         pht(
           'Configured unit test engine "%s" is not a subclass of "%s", '.
           'but must be.',
           $engine_class,
           $base_class));
     }
 
     $engine = newv($engine_class, array())
       ->setWorkingCopy($working_copy)
       ->setConfigurationManager($config);
 
     return $engine;
   }
 
 
   protected function openURIsInBrowser(array $uris) {
     $browser = $this->getBrowserCommand();
     foreach ($uris as $uri) {
       $err = phutil_passthru('%s %s', $browser, $uri);
       if ($err) {
         throw new ArcanistUsageException(
           pht(
             "Failed to open '%s' in browser ('%s'). ".
             "Check your 'browser' config option.",
             $uri,
             $browser));
       }
     }
   }
 
   private function getBrowserCommand() {
     $config = $this->getConfigFromAnySource('browser');
     if ($config) {
       return $config;
     }
 
     if (phutil_is_windows()) {
       return 'start';
     }
 
     $candidates = array('sensible-browser', 'xdg-open', 'open');
 
     // NOTE: The "open" command works well on OS X, but on many Linuxes "open"
     // exists and is not a browser. For now, we're just looking for other
     // commands first, but we might want to be smarter about selecting "open"
     // only on OS X.
 
     foreach ($candidates as $cmd) {
       if (Filesystem::binaryExists($cmd)) {
         return $cmd;
       }
     }
 
     throw new ArcanistUsageException(
       pht(
         "Unable to find a browser command to run. Set '%s' in your ".
         "Arcanist config to specify a command to use.",
         'browser'));
   }
 
 
   /**
    * Ask Phabricator to update the current repository as soon as possible.
    *
    * Calling this method after pushing commits allows Phabricator to discover
    * the commits more quickly, so the system overall is more responsive.
    *
    * @return void
    */
   protected function askForRepositoryUpdate() {
     // If we know which repository we're in, try to tell Phabricator that we
     // pushed commits to it so it can update. This hint can help pull updates
     // more quickly, especially in rarely-used repositories.
     if ($this->getRepositoryCallsign()) {
       try {
         $this->getConduit()->callMethodSynchronous(
           'diffusion.looksoon',
           array(
             'callsigns' => array($this->getRepositoryCallsign()),
           ));
       } catch (ConduitClientException $ex) {
         // If we hit an exception, just ignore it. Likely, we are running
         // against a Phabricator which is too old to support this method.
         // Since this hint is purely advisory, it doesn't matter if it has
         // no effect.
       }
     }
   }
 
 
 }