diff --git a/src/lint/engine/ArcanistLintEngine.php b/src/lint/engine/ArcanistLintEngine.php
index e320fc0c..c03f86e7 100644
--- a/src/lint/engine/ArcanistLintEngine.php
+++ b/src/lint/engine/ArcanistLintEngine.php
@@ -1,612 +1,610 @@
 <?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.
- *
- * @stable
  */
 abstract class ArcanistLintEngine {
 
   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 $postponedLinters = array();
   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 $message) {
         if (!$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);
   }
 
   final public function getPostponedLinters() {
     return $this->postponedLinters;
   }
 
   final public function setPostponedLinters(array $linters) {
     $this->postponedLinters = $linters;
     return $this;
   }
 
   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) {
     $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);
   }
 
 
 }
diff --git a/src/lint/linter/ArcanistLinter.php b/src/lint/linter/ArcanistLinter.php
index 9eb92aaa..9d8e61a8 100644
--- a/src/lint/linter/ArcanistLinter.php
+++ b/src/lint/linter/ArcanistLinter.php
@@ -1,624 +1,623 @@
 <?php
 
 /**
  * Implements lint rules, like syntax checks for a specific language.
  *
  * @task info Human Readable Information
  * @task state Runtime State
  * @task exec Executing Linters
- * @stable
  */
 abstract class ArcanistLinter {
 
   const GRANULARITY_FILE = 1;
   const GRANULARITY_DIRECTORY = 2;
   const GRANULARITY_REPOSITORY = 3;
   const GRANULARITY_GLOBAL = 4;
 
   private $id;
   protected $paths = array();
   private $filteredPaths = null;
   protected $data = array();
   protected $engine;
   protected $activePath;
   protected $messages = array();
 
   protected $stopAllLinters = false;
 
   private $customSeverityMap = array();
   private $customSeverityRules = array();
 
 
 /*  -(  Human Readable Information  )---------------------------------------- */
 
 
   /**
    * Return an optional informative URI where humans can learn more about this
    * linter.
    *
    * For most linters, this should return a link to the project home page. This
    * is shown on `arc linters`.
    *
    * @return string|null Optionally, return an informative URI.
    * @task info
    */
   public function getInfoURI() {
     return null;
   }
 
   /**
    * Return a brief human-readable description of the linter.
    *
    * These should be a line or two, and are shown on `arc linters`.
    *
    * @return string|null Optionally, return a brief human-readable description.
    * @task info
    */
   public function getInfoDescription() {
     return null;
   }
 
   /**
    * Return a human-readable linter name.
    *
    * These are used by `arc linters`, and can let you give a linter a more
    * presentable name.
    *
    * @return string Human-readable linter name.
    * @task info
    */
   public function getInfoName() {
     return nonempty(
       $this->getLinterName(),
       $this->getLinterConfigurationName(),
       get_class($this));
   }
 
 
 /* -(  Runtime State  )------------------------------------------------------ */
 
 
   /**
    * @task state
    */
   final public function getActivePath() {
     return $this->activePath;
   }
 
 
   /**
    * @task state
    */
   final public function setActivePath($path) {
     $this->stopAllLinters = false;
     $this->activePath = $path;
     return $this;
   }
 
 
   /**
    * @task state
    */
   final public function setEngine(ArcanistLintEngine $engine) {
     $this->engine = $engine;
     return $this;
   }
 
 
   /**
    * @task state
    */
   final protected function getEngine() {
     return $this->engine;
   }
 
 
   /**
    * Set the internal ID for this linter.
    *
    * This ID is assigned automatically by the @{class:ArcanistLintEngine}.
    *
    * @param string Unique linter ID.
    * @return this
    * @task state
    */
   final public function setLinterID($id) {
     $this->id = $id;
     return $this;
   }
 
 
   /**
    * Get the internal ID for this linter.
    *
    * Retrieves an internal linter ID managed by the @{class:ArcanistLintEngine}.
    * This ID is a unique scalar which distinguishes linters in a list.
    *
    * @return string Unique linter ID.
    * @task state
    */
   final public function getLinterID() {
     return $this->id;
   }
 
 
 /* -(  Executing Linters  )-------------------------------------------------- */
 
 
   /**
    * Hook called before a list of paths are linted.
    *
    * Parallelizable linters can start multiple requests in parallel here,
    * to improve performance. They can implement @{method:didLintPaths} to
    * collect results.
    *
    * Linters which are not parallelizable should normally ignore this callback
    * and implement @{method:lintPath} instead.
    *
    * @param list<string> A list of paths to be linted
    * @return void
    * @task exec
    */
   public function willLintPaths(array $paths) {
     return;
   }
 
 
   /**
    * Hook called for each path to be linted.
    *
    * Linters which are not parallelizable can do work here.
    *
    * Linters which are parallelizable may want to ignore this callback and
    * implement @{method:willLintPaths} and @{method:didLintPaths} instead.
    *
    * @param string Path to lint.
    * @return void
    * @task exec
    */
   public function lintPath($path) {
     return;
   }
 
 
   /**
    * Hook called after a list of paths are linted.
    *
    * Parallelizable linters can collect results here.
    *
    * Linters which are not paralleizable should normally ignore this callback
    * and implement @{method:lintPath} instead.
    *
    * @param list<string> A list of paths which were linted.
    * @return void
    * @task exec
    */
   public function didLintPaths(array $paths) {
     return;
   }
 
 
   /**
    * Obsolete hook which was invoked before a path was linted.
    *
    * WARNING: This is an obsolete hook which is not called. If you maintain
    * a linter which relies on it, update to use @{method:lintPath} instead.
    *
    * @task exec
    */
   final public function willLintPath($path) {
     // TODO: Remove this method after some time. In the meantime, the "final"
     // will fatal subclasses which implement this hook and point at the API
     // change so maintainers get fewer surprises.
     throw new PhutilMethodNotImplementedException();
   }
 
 
   /**
    * Obsolete hook which was invoked after linters ran.
    *
    * WARNING: This is an obsolete hook which is not called. If you maintain
    * a linter which relies on it, update to use @{method:didLintPaths} instead.
    *
    * @return void
    * @task exec
    */
   final public function didRunLinters() {
     // TODO: Remove this method after some time. In the meantime, the "final"
     // will fatal subclasses which implement this hook and point at the API
     // change so maintainers get fewer surprises.
     throw new PhutilMethodNotImplementedException();
   }
 
 
   public function getLinterPriority() {
     return 1.0;
   }
 
   /**
    * TODO: This should be `final`.
    */
   public function setCustomSeverityMap(array $map) {
     $this->customSeverityMap = $map;
     return $this;
   }
 
   final public function setCustomSeverityRules(array $rules) {
     $this->customSeverityRules = $rules;
     return $this;
   }
 
   final public function getProjectRoot() {
     $engine = $this->getEngine();
     if (!$engine) {
       throw new Exception(
         pht(
           'You must call %s before you can call %s.',
           'setEngine()',
           __FUNCTION__.'()'));
     }
 
     $working_copy = $engine->getWorkingCopy();
     if (!$working_copy) {
       return null;
     }
 
     return $working_copy->getProjectRoot();
   }
 
   final public function getOtherLocation($offset, $path = null) {
     if ($path === null) {
       $path = $this->getActivePath();
     }
 
     list($line, $char) = $this->getEngine()->getLineAndCharFromOffset(
       $path,
       $offset);
 
     return array(
       'path' => $path,
       'line' => $line + 1,
       'char' => $char,
     );
   }
 
   final public function stopAllLinters() {
     $this->stopAllLinters = true;
     return $this;
   }
 
   final public function didStopAllLinters() {
     return $this->stopAllLinters;
   }
 
   final public function addPath($path) {
     $this->paths[$path] = $path;
     $this->filteredPaths = null;
     return $this;
   }
 
   final public function setPaths(array $paths) {
     $this->paths = $paths;
     $this->filteredPaths = null;
     return $this;
   }
 
   /**
    * Filter out paths which this linter doesn't act on (for example, because
    * they are binaries and the linter doesn't apply to binaries).
    *
    * @param  list<string>
    * @return list<string>
    */
   final private function filterPaths(array $paths) {
     $engine = $this->getEngine();
 
     $keep = array();
     foreach ($paths as $path) {
       if (!$this->shouldLintDeletedFiles() && !$engine->pathExists($path)) {
         continue;
       }
 
       if (!$this->shouldLintDirectories() && $engine->isDirectory($path)) {
         continue;
       }
 
       if (!$this->shouldLintBinaryFiles() && $engine->isBinaryFile($path)) {
         continue;
       }
 
       if (!$this->shouldLintSymbolicLinks() && $engine->isSymbolicLink($path)) {
         continue;
       }
 
       $keep[] = $path;
     }
 
     return $keep;
   }
 
   final public function getPaths() {
     if ($this->filteredPaths === null) {
       $this->filteredPaths = $this->filterPaths(array_values($this->paths));
     }
 
     return $this->filteredPaths;
   }
 
   final public function addData($path, $data) {
     $this->data[$path] = $data;
     return $this;
   }
 
   final protected function getData($path) {
     if (!array_key_exists($path, $this->data)) {
       $this->data[$path] = $this->getEngine()->loadData($path);
     }
     return $this->data[$path];
   }
 
   public function getCacheVersion() {
     return 0;
   }
 
 
   final public function getLintMessageFullCode($short_code) {
     return $this->getLinterName().$short_code;
   }
 
   final public function getLintMessageSeverity($code) {
     $map = $this->customSeverityMap;
     if (isset($map[$code])) {
       return $map[$code];
     }
 
     foreach ($this->customSeverityRules as $rule => $severity) {
       if (preg_match($rule, $code)) {
         return $severity;
       }
     }
 
     $map = $this->getLintSeverityMap();
     if (isset($map[$code])) {
       return $map[$code];
     }
 
     return $this->getDefaultMessageSeverity($code);
   }
 
   protected function getDefaultMessageSeverity($code) {
     return ArcanistLintSeverity::SEVERITY_ERROR;
   }
 
   final public function isMessageEnabled($code) {
     return ($this->getLintMessageSeverity($code) !==
             ArcanistLintSeverity::SEVERITY_DISABLED);
   }
 
   final public function getLintMessageName($code) {
     $map = $this->getLintNameMap();
     if (isset($map[$code])) {
       return $map[$code];
     }
     return pht('Unknown lint message!');
   }
 
   final protected function addLintMessage(ArcanistLintMessage $message) {
     $root = $this->getProjectRoot();
     $path = Filesystem::resolvePath($message->getPath(), $root);
     $message->setPath(Filesystem::readablePath($path, $root));
 
     $this->messages[] = $message;
     return $message;
   }
 
   final public function getLintMessages() {
     return $this->messages;
   }
 
   final public function raiseLintAtLine(
     $line,
     $char,
     $code,
     $desc,
     $original = null,
     $replacement = null) {
 
     $message = id(new ArcanistLintMessage())
       ->setPath($this->getActivePath())
       ->setLine($line)
       ->setChar($char)
       ->setCode($this->getLintMessageFullCode($code))
       ->setSeverity($this->getLintMessageSeverity($code))
       ->setName($this->getLintMessageName($code))
       ->setDescription($desc)
       ->setOriginalText($original)
       ->setReplacementText($replacement);
 
     return $this->addLintMessage($message);
   }
 
   final public function raiseLintAtPath($code, $desc) {
     return $this->raiseLintAtLine(null, null, $code, $desc, null, null);
   }
 
   final public function raiseLintAtOffset(
     $offset,
     $code,
     $desc,
     $original = null,
     $replacement = null) {
 
     $path = $this->getActivePath();
     $engine = $this->getEngine();
     if ($offset === null) {
       $line = null;
       $char = null;
     } else {
       list($line, $char) = $engine->getLineAndCharFromOffset($path, $offset);
     }
 
     return $this->raiseLintAtLine(
       $line + 1,
       $char + 1,
       $code,
       $desc,
       $original,
       $replacement);
   }
 
   public function canRun() {
     return true;
   }
 
   abstract public function getLinterName();
 
   public function getVersion() {
     return null;
   }
 
   final protected function isCodeEnabled($code) {
     $severity = $this->getLintMessageSeverity($code);
     return $this->getEngine()->isSeverityEnabled($severity);
   }
 
   public function getLintSeverityMap() {
     return array();
   }
 
   public function getLintNameMap() {
     return array();
   }
 
   public function getCacheGranularity() {
     return self::GRANULARITY_FILE;
   }
 
   /**
    * If this linter is selectable via `.arclint` configuration files, return
    * a short, human-readable name to identify it. For example, `"jshint"` or
    * `"pep8"`.
    *
    * If you do not implement this method, the linter will not be selectable
    * through `.arclint` files.
    */
   public function getLinterConfigurationName() {
     return null;
   }
 
   public function getLinterConfigurationOptions() {
     if (!$this->canCustomizeLintSeverities()) {
       return array();
     }
 
     return array(
       'severity' => array(
         'type' => 'optional map<string|int, string>',
         'help' => pht(
           'Provide a map from lint codes to adjusted severity levels: error, '.
           'warning, advice, autofix or disabled.'),
       ),
       'severity.rules' => array(
         'type' => 'optional map<string, string>',
         'help' => pht(
           'Provide a map of regular expressions to severity levels. All '.
           'matching codes have their severity adjusted.'),
       ),
     );
   }
 
   public function setLinterConfigurationValue($key, $value) {
     $sev_map = array(
       'error'    => ArcanistLintSeverity::SEVERITY_ERROR,
       'warning'  => ArcanistLintSeverity::SEVERITY_WARNING,
       'autofix'  => ArcanistLintSeverity::SEVERITY_AUTOFIX,
       'advice'   => ArcanistLintSeverity::SEVERITY_ADVICE,
       'disabled' => ArcanistLintSeverity::SEVERITY_DISABLED,
     );
 
     switch ($key) {
       case 'severity':
         if (!$this->canCustomizeLintSeverities()) {
           break;
         }
 
         $custom = array();
         foreach ($value as $code => $severity) {
           if (empty($sev_map[$severity])) {
             $valid = implode(', ', array_keys($sev_map));
             throw new Exception(
               pht(
                 'Unknown lint severity "%s". Valid severities are: %s.',
                 $severity,
                 $valid));
           }
           $code = $this->getLintCodeFromLinterConfigurationKey($code);
           $custom[$code] = $severity;
         }
 
         $this->setCustomSeverityMap($custom);
         return;
 
       case 'severity.rules':
         if (!$this->canCustomizeLintSeverities()) {
           break;
         }
 
         foreach ($value as $rule => $severity) {
           if (@preg_match($rule, '') === false) {
             throw new Exception(
               pht(
                 'Severity rule "%s" is not a valid regular expression.',
                 $rule));
           }
           if (empty($sev_map[$severity])) {
             $valid = implode(', ', array_keys($sev_map));
             throw new Exception(
               pht(
                 'Unknown lint severity "%s". Valid severities are: %s.',
                 $severity,
                 $valid));
           }
         }
         $this->setCustomSeverityRules($value);
         return;
     }
 
     throw new Exception(pht('Incomplete implementation: %s!', $key));
   }
 
   protected function canCustomizeLintSeverities() {
     return true;
   }
 
   protected function shouldLintBinaryFiles() {
     return false;
   }
 
   protected function shouldLintDeletedFiles() {
     return false;
   }
 
   protected function shouldLintDirectories() {
     return false;
   }
 
   protected function shouldLintSymbolicLinks() {
     return false;
   }
 
   /**
    * Map a configuration lint code to an `arc` lint code. Primarily, this is
    * intended for validation, but can also be used to normalize case or
    * otherwise be more permissive in accepted inputs.
    *
    * If the code is not recognized, you should throw an exception.
    *
    * @param string  Code specified in configuration.
    * @return string  Normalized code to use in severity map.
    */
   protected function getLintCodeFromLinterConfigurationKey($code) {
     return $code;
   }
 
 }
diff --git a/src/lint/linter/xhpast/ArcanistXHPASTLintNamingHook.php b/src/lint/linter/xhpast/ArcanistXHPASTLintNamingHook.php
index 5bb13513..7848bb13 100644
--- a/src/lint/linter/xhpast/ArcanistXHPASTLintNamingHook.php
+++ b/src/lint/linter/xhpast/ArcanistXHPASTLintNamingHook.php
@@ -1,154 +1,153 @@
 <?php
 
 /**
  * You can extend this class and set `xhpast.naminghook` in your `.arclint` to
  * have an opportunity to override lint results for symbol names.
  *
  * @task override   Overriding Symbol Name Lint Messages
  * @task util       Name Utilities
  * @task internal   Internals
- * @stable
  */
 abstract class ArcanistXHPASTLintNamingHook {
 
 
 /* -(  Internals  )---------------------------------------------------------- */
 
   /**
    * The constructor is final because @{class:ArcanistXHPASTLinter} is
    * responsible for hook instantiation.
    *
    * @return this
    * @task internals
    */
   final public function __construct() {
     // <empty>
   }
 
 
 /* -(  Overriding Symbol Name Lint Messages  )------------------------------- */
 
   /**
    * Callback invoked for each symbol, which can override the default
    * determination of name validity or accept it by returning $default. The
    * symbol types are: xhp-class, class, interface, function, method, parameter,
    * constant, and member.
    *
    * For example, if you want to ban all symbols with "quack" in them and
    * otherwise accept all the defaults, except allow any naming convention for
    * methods with "duck" in them, you might implement the method like this:
    *
    *   if (preg_match('/quack/i', $name)) {
    *     return 'Symbol names containing "quack" are forbidden.';
    *   }
    *   if ($type == 'method' && preg_match('/duck/i', $name)) {
    *     return null; // Always accept.
    *   }
    *   return $default;
    *
    * @param   string      The symbol type.
    * @param   string      The symbol name.
    * @param   string|null The default result from the main rule engine.
    * @return  string|null Null to accept the name, or a message to reject it
    *                      with. You should return the default value if you don't
    *                      want to specifically provide an override.
    * @task override
    */
   abstract public function lintSymbolName($type, $name, $default);
 
 
 /* -(  Name Utilities  )----------------------------------------------------- */
 
   /**
    * Returns true if a symbol name is UpperCamelCase.
    *
    * @param string Symbol name.
    * @return bool True if the symbol is UpperCamelCase.
    * @task util
    */
   public static function isUpperCamelCase($symbol) {
     return preg_match('/^[A-Z][A-Za-z0-9]*$/', $symbol);
   }
 
   /**
    * Returns true if a symbol name is lowerCamelCase.
    *
    * @param string Symbol name.
    * @return bool True if the symbol is lowerCamelCase.
    * @task util
    */
   public static function isLowerCamelCase($symbol) {
     return preg_match('/^[a-z][A-Za-z0-9]*$/', $symbol);
   }
 
   /**
    * Returns true if a symbol name is UPPERCASE_WITH_UNDERSCORES.
    *
    * @param string Symbol name.
    * @return bool True if the symbol is UPPERCASE_WITH_UNDERSCORES.
    * @task util
    */
   public static function isUppercaseWithUnderscores($symbol) {
     return preg_match('/^[A-Z0-9_]+$/', $symbol);
   }
 
   /**
    * Returns true if a symbol name is lowercase_with_underscores.
    *
    * @param string Symbol name.
    * @return bool True if the symbol is lowercase_with_underscores.
    * @task util
    */
   public static function isLowercaseWithUnderscores($symbol) {
     return preg_match('/^[a-z0-9_]+$/', $symbol);
   }
 
   /**
    * Strip non-name components from PHP function symbols. Notably, this discards
    * the "__" magic-method signifier, to make a symbol appropriate for testing
    * with methods like @{method:isLowerCamelCase}.
    *
    * @param   string Symbol name.
    * @return  string Stripped symbol.
    * @task util
    */
   public static function stripPHPFunction($symbol) {
     switch ($symbol) {
       case '__assign_concat':
       case '__call':
       case '__callStatic':
       case '__clone':
       case '__concat':
       case '__construct':
       case '__debugInfo':
       case '__destruct':
       case '__get':
       case '__invoke':
       case '__isset':
       case '__set':
       case '__set_state':
       case '__sleep':
       case '__toString':
       case '__unset':
       case '__wakeup':
         return preg_replace('/^__/', '', $symbol);
 
       default:
         return $symbol;
     }
   }
 
   /**
    * Strip non-name components from PHP variable symbols. Notably, this discards
    * the "$", to make a symbol appropriate for testing with methods like
    * @{method:isLowercaseWithUnderscores}.
    *
    * @param string Symbol name.
    * @return string Stripped symbol.
    * @task util
    */
   public static function stripPHPVariable($symbol) {
     return preg_replace('/^\$/', '', $symbol);
   }
 
 }
diff --git a/src/workflow/ArcanistWorkflow.php b/src/workflow/ArcanistWorkflow.php
index bf40a309..5689b7ab 100644
--- a/src/workflow/ArcanistWorkflow.php
+++ b/src/workflow/ArcanistWorkflow.php
@@ -1,1958 +1,1956 @@
 <?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
- *
- * @stable
  */
 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;
   private $passedArguments;
   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)));
     }
 
     $uncommitted = $api->getUncommittedChanges();
     $unstaged = $api->getUnstagedChanges();
 
     // We only want files which are purely uncommitted.
     $uncommitted = array_diff($uncommitted, $unstaged);
 
     $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(
           "%s\n\n",
           pht(
             'This feature requires a newer version of Phabricator. Please '.
             'update it using these instructions: %s',
             'http://www.phabricator.com/docs/phabricator/article/'.
             'Installation_Guide.html#updating-phabricator'));
       }
       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;
   }
 
   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.
       }
     }
   }
 
 
 }