diff --git a/core/lib/Drupal/Core/Booze/DrunkController.php b/core/lib/Drupal/Core/Booze/DrunkController.php
index 4bd1cd3..ad07fdf 100644
--- a/core/lib/Drupal/Core/Booze/DrunkController.php
+++ b/core/lib/Drupal/Core/Booze/DrunkController.php
@@ -112,11 +112,12 @@ public function respond(Request $request, BoundDisplayInterface $_display) {
     $this->response = new Response();
 
     $this->renderBlocks($request);
-    $this->renderLayout($request);
+    $this->renderRegions($request);
     // @todo handle out-of-band stuff, e.g. css/js
 
-    $content = $this->display->getLayoutPluginInstance()->renderLayout($this->renderedRegions);
-    $this->response->setContent($content);
+    $content = $this->display->getLayoutInstance()->renderLayout(FALSE, $this->renderedRegions);
+
+    $this->response->setContent($this->wrapHtml($content));
 
     return $this->response;
   }
@@ -165,17 +166,75 @@ protected function renderBlocks(Request $request) {
    *
    * @param \Symfony\Component\HttpFoundation\Request $request
    */
-  protected function renderLayout(Request $request) {
-    $layout = $this->display->getLayoutPluginInstance();
+  protected function renderRegions(Request $request) {
+    $layout = $this->display->getLayoutInstance();
     // @todo need to add this method to the layout plugin interface.
-    // @todo this is another place we could do block placement renegotiation by region role (@see Display)
     foreach ($layout->getRegions() as $region => $info) {
       // @todo region styles, if we do them, would go in around here
       $to_render = array();
-      foreach ($this->display->getBlocksByRegion($region) as $block) {
+      // This sorting call will trigger automatic block remapping if the display
+      // has had a different layout plugin instance injected than the one
+      // indicated in storage.
+      foreach ($this->display->getSortedBlocksByRegion($region) as $block) {
         $to_render[] = $this->renderedBlocks[$block];
       }
-      $this->renderedRegions[$region] = $layout->renderRegion($region);
+      /*
+       * @todo giant fat utter hack to just get it working.
+       * the responsibility for this in Panels is in styles - we haven't
+       * implemented those yet, and they create a potentially awkward additional
+       * separation for frontenders that we may not want to have.
+       *
+       * so, needs a little discussion, but it's (sorta) ok to just force this
+       * to work while we figure it out.
+       */
+      $this->renderedRegions[$region] = implode("\n", $to_render);
+    }
+  }
+
+  /**
+   * Wraps page output in the html template.
+   *
+   * @todo This is ENTIRELY a shim until https://drupal.org/node/1871596 gets in.
+   *
+   * @param $content
+   */
+  protected function wrapHtml($content) {
+    $page = element_info('page');
+    foreach ($this->moduleHandler->getImplementations('page_build') as $module) {
+      $function = $module . '_page_build';
+      $function($page);
+    }
+    $this->moduleHandler->alter('page', $page);
+
+    // ensure the #attached assets get picked up
+    drupal_process_attached($page);
+
+    $vars = array(
+      'page' => array(
+        '#type' => 'markup',
+        '#markup' => $content,
+        '#children' => $content, // @todo some preprocessors demand this be here
+        'page_top' => empty($page['page_top']) ? array(): $page['page_top'],
+        'page_bottom' => empty($page['page_bottom']) ? array(): $page['page_bottom'],
+      ),
+    );
+
+    // extra-ugly hack for sidebar-number-correctness. ugh, template_preprocess_html.
+    $layout = $this->display->getLayoutInstance();
+    $i = 0;
+    foreach ($layout->getRegions() as $name => $info) {
+      if (strpos($name, 'sidebar') === 0) {
+        $i++;
+      }
     }
+
+    if ($i >= 1) {
+      $vars['page']['sidebar_first'] = TRUE;
+    }
+    if ($i >= 2) {
+      $vars['page']['sidebar_second'] = TRUE;
+    }
+
+    return theme('html', $vars);
   }
 }
diff --git a/core/modules/layout/layout.module b/core/modules/layout/layout.module
index c6ed7ae..12b0b9f 100644
--- a/core/modules/layout/layout.module
+++ b/core/modules/layout/layout.module
@@ -76,6 +76,7 @@ function layout_theme($existing, $type, $theme, $path) {
       'variables' => array('content' => NULL),
       'path' => $layout['path'],
       'template' => $layout['template'],
+      'base hook' => 'page',
     );
   }
   return $items;
diff --git a/core/modules/layout/lib/Drupal/layout/Config/DisplayBase.php b/core/modules/layout/lib/Drupal/layout/Config/DisplayBase.php
index afe3229..02f6f3b 100644
--- a/core/modules/layout/lib/Drupal/layout/Config/DisplayBase.php
+++ b/core/modules/layout/lib/Drupal/layout/Config/DisplayBase.php
@@ -135,4 +135,15 @@ public function getAllRegionTypes() {
     }
     return array_unique($types);
   }
+
+  /**
+   * Overrides \Drupal\Core\Config\Entity\ConfigEntityBase::getExportProperties();
+   *
+   * @return array
+   */
+  public function getExportProperties() {
+    $properties = parent::getExportProperties();
+    $properties['blockInfo'] = $this->blockInfo;
+    return $properties;
+  }
 }
diff --git a/core/modules/layout/lib/Drupal/layout/Config/DisplayStorageController.php b/core/modules/layout/lib/Drupal/layout/Config/DisplayStorageController.php
new file mode 100644
index 0000000..f6a9567
--- /dev/null
+++ b/core/modules/layout/lib/Drupal/layout/Config/DisplayStorageController.php
@@ -0,0 +1,19 @@
+<?php
+/**
+ * @file
+ * Contains Drupal\layout\Config\UnboundDisplayStorageController.
+ */
+
+namespace Drupal\layout\Config;
+
+use Drupal\Core\Config\Entity\ConfigStorageController;
+use Drupal\layout\Plugin\Core\Entity\Display;
+
+/**
+ * Storage controller for Displays.
+ *
+ * @see \Drupal\layout\Config\BoundDisplayInterface
+ */
+class UnboundDisplayStorageController extends ConfigStorageController {
+  // @todo nothing yet...but soon.
+}
diff --git a/core/modules/layout/lib/Drupal/layout/Config/UnboundDisplayStorageController.php b/core/modules/layout/lib/Drupal/layout/Config/UnboundDisplayStorageController.php
index dc28ef3..c139a71 100644
--- a/core/modules/layout/lib/Drupal/layout/Config/UnboundDisplayStorageController.php
+++ b/core/modules/layout/lib/Drupal/layout/Config/UnboundDisplayStorageController.php
@@ -8,6 +8,7 @@
 
 use Drupal\Core\Config\Entity\ConfigStorageController;
 use Drupal\layout\Plugin\Core\Entity\Display;
+use Drupal\Core\Config\Config;
 
 /**
  * Storage controller for Unbound Displays.
diff --git a/core/modules/system/lib/Drupal/system/Plugin/block/block/SystemMainBlock.php b/core/modules/system/lib/Drupal/system/Plugin/block/block/SystemMainBlock.php
index ea6a137..4121628 100644
--- a/core/modules/system/lib/Drupal/system/Plugin/block/block/SystemMainBlock.php
+++ b/core/modules/system/lib/Drupal/system/Plugin/block/block/SystemMainBlock.php
@@ -32,7 +32,7 @@ public function build() {
     }
 
     $callback = $this->entity->get('_content_closure');
-    return call_user_func($callback);
+    return is_callable($callback) ? call_user_func($callback) : '';
   }
 
 }
diff --git a/core/profiles/standard/config/display.bound.frontend.yml b/core/profiles/standard/config/display.bound.frontend.yml
index e1161b4..2c629cf 100644
--- a/core/profiles/standard/config/display.bound.frontend.yml
+++ b/core/profiles/standard/config/display.bound.frontend.yml
@@ -5,31 +5,31 @@ layoutSettings: { }
 blockInfo:
 # these have bartik in their namespace, but that's irrelevant to our use here -
 # we're just reusing them while we get everything together.
-  block.block.bartik.help:
+  bartik.help:
     region: help
     region-type: content
     weight: 0 # should float in unbound/master
-  block.block.bartik.content:
+  bartik.content:
     region: content
     region-type: content
     weight: 0 # should float in unbound/master
-  block.block.bartik.footer:
+  bartik.footer:
     region: footer
     region-type: footer
     weight: 0 # stick-top in unbound/master
-  block.block.bartik.powered:
+  bartik.powered:
     region: footer
     region-type: footer
     weight: 10 # float in unbound/master
-  block.block.bartik.search:
+  bartik.search:
     region: sidebar_first
     region-type: aside
     weight: 0 # stick-top in unbound/master
-  block.block.bartik.login:
+  bartik.login:
     region: sidebar_first
     region-type: aside
     weight: 10 # stick-top in unbound/master
-  block.block.bartik.tools:
+  bartik.tools:
     region: sidebar_first
     region-type: aside
-    weight: 20 # stick-top in unbound/master
\ No newline at end of file
+    weight: 20 # stick-top in unbound/master
diff --git a/core/themes/bartik/layouts/static/frontend/frontend.html.twig b/core/themes/bartik/layouts/static/frontend/frontend.html.twig
index 195e411..857a1d1 100644
--- a/core/themes/bartik/layouts/static/frontend/frontend.html.twig
+++ b/core/themes/bartik/layouts/static/frontend/frontend.html.twig
@@ -63,24 +63,24 @@ Page content (in order of occurrence in the default page.tpl.php):
   comment/reply/12345).
 
 Regions:
-- page.header: Items for the header region.
-- page.featured: Items for the featured region.
-- page.highlighted: Items for the highlighted content region.
-- page.help: Dynamic help text, mostly for admin pages.
-- page.content: The main content of the current page.
-- page.sidebar_first: Items for the first sidebar.
-- page.sidebar_second: Items for the second sidebar.
-- page.triptych_first: Items for the first triptych.
-- page.triptych_middle: Items for the middle triptych.
-- page.triptych_last: Items for the last triptych.
-- page.footer_firstcolumn: Items for the first footer column.
-- page.footer_secondcolumn: Items for the second footer column.
-- page.footer_thirdcolumn: Items for the third footer column.
-- page.footer_fourthcolumn: Items for the fourth footer column.
-- page.footer: Items for the footer region.
+- content.header: Items for the header region.
+- content.featured: Items for the featured region.
+- content.highlighted: Items for the highlighted content region.
+- content.help: Dynamic help text, mostly for admin pages.
+- content.content: The main content of the current page.
+- content.sidebar_first: Items for the first sidebar.
+- content.sidebar_second: Items for the second sidebar.
+- content.triptych_first: Items for the first triptych.
+- content.triptych_middle: Items for the middle triptych.
+- content.triptych_last: Items for the last triptych.
+- content.footer_firstcolumn: Items for the first footer column.
+- content.footer_secondcolumn: Items for the second footer column.
+- content.footer_thirdcolumn: Items for the third footer column.
+- content.footer_fourthcolumn: Items for the fourth footer column.
+- content.footer: Items for the footer region.
 
 @see template_preprocess()
-@see template_preprocess_page()
+@see template_preprocess_content()
 @see template_process()
 @see bartik_process_page()
 @see html.tpl.php
@@ -90,62 +90,60 @@ Regions:
 #}
 
 {# system is emitted before & above everything else #}
-{% if page.system %}{{ page.system }}{% endif %}
+{% if content.system %}{{ content.system }}{% endif %}
 
 <div id="page">
-  {% if page.header %}
-    <header id="header" role="banner"><div class="section clearfix">
-      {# @todo remove/replace this hardcoding. #}
-      {% if secondary_nav %}
-        <nav id="secondary-menu" class="navigation" role="navigation">
-          {{ secondary_nav }}
-        </nav>
-      {% endif %}
+  <header id="header" role="banner"><div class="section clearfix">
+    {# @todo remove/replace this hardcoding. #}
+    {% if secondary_nav %}
+      <nav id="secondary-menu" class="navigation" role="navigation">
+        {{ secondary_nav }}
+      </nav>
+    {% endif %}
 
-      {# @todo remove/replace this hardcoding. #}
-      {% if logo %}
-        <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home" id="logo">
-          <img src="{{ logo }}" alt="{{ 'Home'|t }}" />
-        </a>
-      {% endif %}
+    {# @todo remove/replace this hardcoding. #}
+    {% if logo %}
+      <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home" id="logo">
+        <img src="{{ logo }}" alt="{{ 'Home'|t }}" />
+      </a>
+    {% endif %}
 
-      {# @todo remove/replace aaaaall this hardcoding. #}
-      {% if site_name or site_slogan %}
-        <div id="name-and-slogan" {% if hide_site_name and hide_site_slogan %}class="element-invisible"{% endif %}>
-          {% if site_name %}
-            {% if title %}
-              <div id="site-name" {% if hide_site_name %}class="element-invisible"{% endif %}>
-                <strong>
-                  <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home"><span><{{ site_name }}></span></a>
-                </strong>
-              </div>
-            {% else %}
-              <h1 id="site-name" {% if hide_site_name %}class="element-invisible"{% endif %}>
+    {# @todo remove/replace aaaaall this hardcoding. #}
+    {% if site_name or site_slogan %}
+      <div id="name-and-slogan" {% if hide_site_name and hide_site_slogan %}class="element-invisible"{% endif %}>
+        {% if site_name %}
+          {% if title %}
+            <div id="site-name" {% if hide_site_name %}class="element-invisible"{% endif %}>
+              <strong>
                 <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home"><span><{{ site_name }}></span></a>
-              </h1>
-            {% endif %}
-          {% endif %}
-
-          {% if site_slogan %}
-            <div id="site-slogan" {% if hide_site_slogan %}class="element-invisible"{% endif %}>
-              {{ site_slogan }}
+              </strong>
             </div>
+          {% else %}
+            <h1 id="site-name" {% if hide_site_name %}class="element-invisible"{% endif %}>
+              <a href="{{ front_page }}" title="{{ 'Home'|t }}" rel="home"><span><{{ site_name }}></span></a>
+            </h1>
           {% endif %}
+        {% endif %}
 
-        </div>
-      {% endif %}
+        {% if site_slogan %}
+          <div id="site-slogan" {% if hide_site_slogan %}class="element-invisible"{% endif %}>
+            {{ site_slogan }}
+          </div>
+        {% endif %}
 
-      {{ page.header }}
+      </div>
+    {% endif %}
 
-      {# @todo remove/replace this hardcoding. #}
-      {% if primary_nav %}
-        <nav id="main-menu" class="navigation" role="navigation">
-          {{ primary_nav }}
-        </nav>
-      {% endif %}
+    {{ content.header }}
 
-    </div></header>
-  {% endif %}
+    {# @todo remove/replace this hardcoding. #}
+    {% if primary_nav %}
+      <nav id="main-menu" class="navigation" role="navigation">
+        {{ primary_nav }}
+      </nav>
+    {% endif %}
+
+  </div></header>
 
 
   {# @todo remove/replace this hardcoding. #}
@@ -156,9 +154,9 @@ Regions:
   {% endif %}
 
 
-  {% if page.featured %}
+  {% if content.featured %}
     <aside id="featured"><div class="section clearfix">
-      {{ page.featured }}
+      {{ content.featured }}
     </div></aside>
   {% endif %}
 
@@ -166,9 +164,9 @@ Regions:
   <div id="main-wrapper" class="clearfix"><div id="main" class="clearfix">
     {{ breadcrumb }} {# @todo remove/replace this hardcoding. #}
     <main id="content" class="column" role="main"><section class="section">
-      {% if page.highlighted %}
+      {% if content.highlighted %}
         <div id="highlighted">
-          {{ page.highlighted }}
+          {{ content.highlighted }}
         </div>
       {% endif %}
 
@@ -190,8 +188,8 @@ Regions:
         </nav>
       {% endif %}
 
-      {# @todo page.help should probably be a block, not a region #}
-      {{ page.help }}
+      {# @todo content.help should probably be a block, not a region #}
+      {{ content.help }}
 
       {# @todo remove/replace this hardcoding. #}
       {% if action_links %}
@@ -200,51 +198,51 @@ Regions:
         </ul>
       {% endif %}
 
-      {{ page.content }}
+      {{ content.content }}
 
       {# @todo remove/replace this hardcoding. #}
       {{ feed_icons }}
 
     </section></main>
 
-    {% if page.sidebar_first %}
+    {% if content.sidebar_first %}
       <div id="sidebar-first" class="column sidebar"><aside class="section">
-        {{ page.sidebar_first }}
+        {{ content.sidebar_first }}
       </aside></div>
     {% endif %}
 
-    {% if page.sidebar_second %}
+    {% if content.sidebar_second %}
       <div id="sidebar-first" class="column sidebar"><aside class="section">
-        {{ page.sidebar_first }}
+        {{ content.sidebar_first }}
       </aside></div>
     {% endif %}
 
   </div></div>
 
 
-  {% if page.triptych_first or page.triptych_middle or page.triptych_last %}
+  {% if content.triptych_first or content.triptych_middle or content.triptych_last %}
     <div id="triptych-wrapper"><aside id="triptych" class="clearfix">
-      {{ page.triptych_first }}
-      {{ page.triptych_middle }}
-      {{ page.triptych_last }}
+      {{ content.triptych_first }}
+      {{ content.triptych_middle }}
+      {{ content.triptych_last }}
     </aside></div>
   {% endif %}
 
 
   <div id="footer-wrapper"><footer class="section" role="contentinfo">
-    {% if page.footer_firstcolumn or page.footer_secondcolumn
-       or page.footer_thirdcolumn or page.footer_fourthcolumn %}
+    {% if content.footer_firstcolumn or content.footer_secondcolumn
+       or content.footer_thirdcolumn or content.footer_fourthcolumn %}
       <div id="footer-columns" class="clearfix">
-        {{ page.footer_firstcolumn }}
-        {{ page.footer_secondcolumn }}
-        {{ page.footer_thirdcolumn }}
-        {{ page.footer_fourthcolumn }}
+        {{ content.footer_firstcolumn }}
+        {{ content.footer_secondcolumn }}
+        {{ content.footer_thirdcolumn }}
+        {{ content.footer_fourthcolumn }}
       </div>
     {% endif %}
 
-    {% if page.footer %}
+    {% if content.footer %}
       <div id="footer" role="contentinfo" class="clearfix">
-        {{ page.footer }}
+        {{ content.footer }}
       </div>
     {% endif %}
   </footer></div>