diff --git a/conf/default.conf.php b/conf/default.conf.php
index 426d00f774..6b856ea69f 100644
--- a/conf/default.conf.php
+++ b/conf/default.conf.php
@@ -1199,4 +1199,21 @@ return array(
   'style.monospace' => '10px "Menlo", "Consolas", "Monaco", monospace',
 
 
+// -- Debugging ------------------------------------------------------------- //
+
+  // Enable this to change HTTP redirects into normal pages with a link to the
+  // redirection target. For example, after you submit a form you'll get a page
+  // saying "normally, you'd be redirected...". This is useful to examine
+  // service or profiler information on write pathways, or debug redirects. It
+  // also makes the UX horrible for normal use, so you should enable it only
+  // when debugging.
+  //
+  // NOTE: This does not currently work for forms with Javascript "workflow",
+  // since the redirect happens in Javascript.
+  'debug.stop-on-redirect'    => false,
+
+  // Enable this to always profile every page. This is very slow! You should
+  // only enable it when debugging.
+  'debug.profile-every-request'  => false,
+
 );
diff --git a/src/aphront/console/plugin/DarkConsoleXHProfPlugin.php b/src/aphront/console/plugin/DarkConsoleXHProfPlugin.php
index e2a03d7804..0c38b60f99 100644
--- a/src/aphront/console/plugin/DarkConsoleXHProfPlugin.php
+++ b/src/aphront/console/plugin/DarkConsoleXHProfPlugin.php
@@ -103,8 +103,8 @@ final class DarkConsoleXHProfPlugin extends DarkConsolePlugin {
 
 
   public function willShutdown() {
-    if (isset($_REQUEST['__profile__']) &&
-        $_REQUEST['__profile__'] != 'all') {
+    if (DarkConsoleXHProfPluginAPI::isProfilerRequested() &&
+        (DarkConsoleXHProfPluginAPI::isProfilerRequested() !== 'all')) {
       $this->xhprofID = DarkConsoleXHProfPluginAPI::stopProfiler();
     }
   }
diff --git a/src/aphront/console/plugin/xhprof/DarkConsoleXHProfPluginAPI.php b/src/aphront/console/plugin/xhprof/DarkConsoleXHProfPluginAPI.php
index 38bc063aed..8ab312c4df 100644
--- a/src/aphront/console/plugin/xhprof/DarkConsoleXHProfPluginAPI.php
+++ b/src/aphront/console/plugin/xhprof/DarkConsoleXHProfPluginAPI.php
@@ -29,6 +29,18 @@ final class DarkConsoleXHProfPluginAPI {
     return extension_loaded('xhprof');
   }
 
+  public static function isProfilerRequested() {
+    if (!empty($_REQUEST['__profile__'])) {
+      return $_REQUEST['__profile__'];
+    }
+
+    if (PhabricatorEnv::getEnvConfig('debug.profile-every-request')) {
+      return PhabricatorEnv::getEnvConfig('debug.profile-every-request');
+    }
+
+    return false;
+  }
+
   public static function includeXHProfLib() {
     // TODO: this is incredibly stupid, but we may not have Phutil metamodule
     // stuff loaded yet so we can't just phutil_get_library_root() our way
@@ -41,8 +53,9 @@ final class DarkConsoleXHProfPluginAPI {
     require_once $root.'/externals/xhprof/xhprof_lib.php';
   }
 
+
   public static function hookProfiler() {
-    if (empty($_REQUEST['__profile__'])) {
+    if (!self::isProfilerRequested()) {
       return;
     }
 
@@ -71,17 +84,41 @@ final class DarkConsoleXHProfPluginAPI {
       $data = serialize($data);
       $file_class = 'PhabricatorFile';
 
-      // Since these happen on GET we can't do guarded writes.
-      $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
+      // Since these happen on GET we can't do guarded writes. These also
+      // sometimes happen after we've disposed of the write guard; in this
+      // case we need to disable the whole mechanism.
 
-      $file = call_user_func(
-        array($file_class, 'newFromFileData'),
-        $data,
-        array(
-          'mime-type' => 'application/xhprof',
-          'name'      => 'profile.xhprof',
-        ));
-      return $file->getPHID();
+      $use_scope = AphrontWriteGuard::isGuardActive();
+      if ($use_scope) {
+        $unguarded = AphrontWriteGuard::beginScopedUnguardedWrites();
+      } else {
+        AphrontWriteGuard::allowDangerousUnguardedWrites(true);
+      }
+
+      $caught = null;
+      try {
+        $file = call_user_func(
+          array($file_class, 'newFromFileData'),
+          $data,
+          array(
+            'mime-type' => 'application/xhprof',
+            'name'      => 'profile.xhprof',
+          ));
+      } catch (Exception $ex) {
+        $caught = $ex;
+      }
+
+      if ($use_scope) {
+        unset($unguarded);
+      } else {
+        AphrontWriteGuard::allowDangerousUnguardedWrites(false);
+      }
+
+      if ($caught) {
+        throw $caught;
+      } else {
+        return $file->getPHID();
+      }
     } else {
       return null;
     }
diff --git a/src/aphront/response/AphrontRedirectResponse.php b/src/aphront/response/AphrontRedirectResponse.php
index f49681436b..7d060bb16b 100644
--- a/src/aphront/response/AphrontRedirectResponse.php
+++ b/src/aphront/response/AphrontRedirectResponse.php
@@ -34,15 +34,47 @@ class AphrontRedirectResponse extends AphrontResponse {
     return (string)$this->uri;
   }
 
+  public function shouldStopForDebugging() {
+    return PhabricatorEnv::getEnvConfig('debug.stop-on-redirect');
+  }
+
   public function getHeaders() {
-    $headers = array(
-      array('Location', $this->uri),
-    );
+    $headers = array();
+    if (!$this->shouldStopForDebugging()) {
+      $headers[] = array('Location', $this->uri);
+    }
     $headers = array_merge(parent::getHeaders(), $headers);
     return $headers;
   }
 
   public function buildResponseString() {
+    if ($this->shouldStopForDebugging()) {
+      $view = new PhabricatorStandardPageView();
+      $view->setRequest($this->getRequest());
+      $view->setApplicationName('Debug');
+      $view->setTitle('Stopped on Redirect');
+
+      $error = new AphrontErrorView();
+      $error->setSeverity(AphrontErrorView::SEVERITY_NOTICE);
+      $error->setTitle('Stopped on Redirect');
+
+      $link = phutil_render_tag(
+        'a',
+        array(
+          'href' => $this->getURI(),
+        ),
+        'Continue to: '.phutil_escape_html($this->getURI()));
+
+      $error->appendChild(
+        '<p>You were stopped here because <tt>debug.stop-on-redirect</tt> '.
+        'is set in your configuration.</p>'.
+        '<p>'.$link.'</p>');
+
+      $view->appendChild($error);
+
+      return $view->render();
+    }
+
     return '';
   }
 
diff --git a/src/aphront/writeguard/AphrontWriteGuard.php b/src/aphront/writeguard/AphrontWriteGuard.php
index 38d6ce7ad2..e0a61284cf 100644
--- a/src/aphront/writeguard/AphrontWriteGuard.php
+++ b/src/aphront/writeguard/AphrontWriteGuard.php
@@ -108,6 +108,17 @@ final class AphrontWriteGuard {
   }
 
 
+  /**
+   * Determine if there is an active write guard.
+   *
+   * @return bool
+   * @task manage
+   */
+  public static function isGuardActive() {
+    return (bool)self::$instance;
+  }
+
+
 /* -(  Protecting Writes  )-------------------------------------------------- */
 
 
diff --git a/webroot/index.php b/webroot/index.php
index 1b5076134a..cfca18e57a 100644
--- a/webroot/index.php
+++ b/webroot/index.php
@@ -220,8 +220,8 @@ $headers = array_merge($headers, $response->getHeaders());
 $sink->writeHeaders($headers);
 
 // TODO: This shouldn't be possible in a production-configured environment.
-if (isset($_REQUEST['__profile__']) &&
-    ($_REQUEST['__profile__'] == 'all')) {
+if (DarkConsoleXHProfPluginAPI::isProfilerRequested() &&
+    DarkConsoleXHProfPluginAPI::isProfilerRequested() === 'all') {
   $profile = DarkConsoleXHProfPluginAPI::stopProfiler();
   $profile =
     '<div style="text-align: center; background: #ff00ff; padding: 1em;