--- a/candolint/handlers.py	Sat Sep 16 17:41:43 2017 +0800
+++ b/candolint/handlers.py	Mon Sep 18 14:27:41 2017 +0800
@@ -150,7 +150,20 @@
         for line in lines:
             if 'filename' in line:
                 line['link'] = adapter.get_line_url(check.change, line)
-        self.render('check.html', project=project, check=check, lines=lines, adapter=adapter)
+        if check.success:
+            reference = (Check
+                .select(*Check.get_light_fields())
+                .join(Change)
+                .where(Check.project == check.project)
+                .where(Check.success == True)
+                .where(Check.change != check.change)
+                .where(Change.branch == check.change.branch)
+                .where(Check.ordinal < check.ordinal)
+                .order_by(Check.ordinal.desc())
+                .first())
+        else:
+            reference = None
+        self.render('check.html', project=project, check=check, lines=lines, adapter=adapter, reference=reference)
 
 
 class CompareHandler(BaseHandler):

--- a/templates/check.html	Sat Sep 16 17:41:43 2017 +0800
+++ b/templates/check.html	Mon Sep 18 14:27:41 2017 +0800
@@ -46,6 +46,27 @@
         </dl>
       </div>
     </div>
+    {% if reference is not None %}
+      <p>
+        Overall,
+        {% if check.errors > reference.errors %}
+          <span class="uk-text-danger">worse</span> than
+        {% elif check.errors < reference.errors %}
+          <span class="uk-text-success">better</span> than
+        {% else %}
+          {% if check.warnings > reference.warnings %}
+            <span class="uk-text-warning">worse</span> than
+          {% elif check.warnings < reference.warnings %}
+            <span class="uk-text-success">better</span> than
+          {% else %}
+            same as
+          {% end %}
+        {% end %}
+        <a href="{{ project.get_url() }}/{{ reference.ordinal }}">check #{{ reference.ordinal }}</a>,
+        the previous check on branch {{ change.branch }}
+        (<a href="{{ project.get_url() }}/{{ check.ordinal }}/compare/{{ reference.ordinal }}">compare</a>).
+      </p>
+    {% end %}
     {% include ui/check-log.html %}
   </div>
 {% end %}