diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -2550,6 +2550,7 @@
     'PhrequentSearchEngine' => 'applications/phrequent/query/PhrequentSearchEngine.php',
     'PhrequentTimeBlock' => 'applications/phrequent/storage/PhrequentTimeBlock.php',
     'PhrequentTimeBlockTestCase' => 'applications/phrequent/storage/__tests__/PhrequentTimeBlockTestCase.php',
+    'PhrequentTimeSlices' => 'applications/phrequent/storage/PhrequentTimeSlices.php',
     'PhrequentTrackController' => 'applications/phrequent/controller/PhrequentTrackController.php',
     'PhrequentTrackableInterface' => 'applications/phrequent/interface/PhrequentTrackableInterface.php',
     'PhrequentTrackingEditor' => 'applications/phrequent/editor/PhrequentTrackingEditor.php',
@@ -5521,6 +5522,7 @@
     'PhrequentSearchEngine' => 'PhabricatorApplicationSearchEngine',
     'PhrequentTimeBlock' => 'Phobject',
     'PhrequentTimeBlockTestCase' => 'PhabricatorTestCase',
+    'PhrequentTimeSlices' => 'Phobject',
     'PhrequentTrackController' => 'PhrequentController',
     'PhrequentTrackingEditor' => 'PhabricatorEditor',
     'PhrequentUIEventListener' => 'PhabricatorEventListener',
diff --git a/src/applications/phrequent/conduit/ConduitAPI_phrequent_tracking_Method.php b/src/applications/phrequent/conduit/ConduitAPI_phrequent_tracking_Method.php
--- a/src/applications/phrequent/conduit/ConduitAPI_phrequent_tracking_Method.php
+++ b/src/applications/phrequent/conduit/ConduitAPI_phrequent_tracking_Method.php
@@ -31,6 +31,7 @@
     $times = id(new PhrequentUserTimeQuery())
       ->setViewer($user)
       ->needPreemptingEvents(true)
+      ->withEnded(PhrequentUserTimeQuery::ENDED_NO)
       ->withUserPHIDs(array($user->getPHID()))
       ->execute();
 
diff --git a/src/applications/phrequent/query/PhrequentUserTimeQuery.php b/src/applications/phrequent/query/PhrequentUserTimeQuery.php
--- a/src/applications/phrequent/query/PhrequentUserTimeQuery.php
+++ b/src/applications/phrequent/query/PhrequentUserTimeQuery.php
@@ -199,7 +199,7 @@
           $u_start = $u_event->getDateStarted();
           $u_end = $u_event->getDateEnded();
 
-          if (($u_start >= $e_start) && ($u_end <= $e_end) &&
+          if (($u_start >= $e_start) &&
               ($u_end === null || $u_end > $e_start)) {
             $select[] = $u_event;
           }
diff --git a/src/applications/phrequent/storage/PhrequentTimeBlock.php b/src/applications/phrequent/storage/PhrequentTimeBlock.php
--- a/src/applications/phrequent/storage/PhrequentTimeBlock.php
+++ b/src/applications/phrequent/storage/PhrequentTimeBlock.php
@@ -10,17 +10,16 @@
   }
 
   public function getTimeSpentOnObject($phid, $now) {
-    $ranges = idx($this->getObjectTimeRanges($now), $phid, array());
+    $slices = idx($this->getObjectTimeRanges(), $phid);
 
-    $sum = 0;
-    foreach ($ranges as $range) {
-      $sum += ($range[1] - $range[0]);
+    if (!$slices) {
+      return null;
     }
 
-    return $sum;
+    return $slices->getDuration($now);
   }
 
-  public function getObjectTimeRanges($now) {
+  public function getObjectTimeRanges() {
     $ranges = array();
 
     $range_start = time();
@@ -29,6 +28,7 @@
     }
 
     $object_ranges = array();
+    $object_ongoing = array();
     foreach ($this->events as $event) {
 
       // First, convert each event's preempting stack into a linear timeline
@@ -42,14 +42,16 @@
       );
       $timeline[] = array(
         'event' => $event,
-        'at' => (int)nonempty($event->getDateEnded(), $now),
+        'at' => (int)nonempty($event->getDateEnded(), PHP_INT_MAX),
         'type' => 'end',
       );
 
       $base_phid = $event->getObjectPHID();
+      if (!$event->getDateEnded()) {
+        $object_ongoing[$base_phid] = true;
+      }
 
       $preempts = $event->getPreemptingEvents();
-
       foreach ($preempts as $preempt) {
         $same_object = ($preempt->getObjectPHID() == $base_phid);
         $timeline[] = array(
@@ -59,7 +61,7 @@
         );
         $timeline[] = array(
           'event' => $preempt,
-          'at' => (int)nonempty($preempt->getDateEnded(), $now),
+          'at' => (int)nonempty($preempt->getDateEnded(), PHP_INT_MAX),
           'type' => $same_object ? 'end' : 'pop',
         );
       }
@@ -89,7 +91,6 @@
       $stratum = null;
       $strata = array();
 
-
       $ranges = array();
       foreach ($timeline as $timeline_event) {
         $id = $timeline_event['event']->getID();
@@ -173,15 +174,39 @@
         }
       }
 
+      // Filter out ranges with an indefinite start time. These occur when
+      // popping the stack when there are multiple ongoing events.
+      foreach ($ranges as $key => $range) {
+        if ($range[0] == PHP_INT_MAX) {
+          unset($ranges[$key]);
+        }
+      }
+
       $object_ranges[$base_phid][] = $ranges;
     }
 
-    // Finally, collapse all the ranges so we don't double-count time.
-
+    // Collapse all the ranges so we don't double-count time.
     foreach ($object_ranges as $phid => $ranges) {
       $object_ranges[$phid] = self::mergeTimeRanges(array_mergev($ranges));
     }
 
+    foreach ($object_ranges as $phid => $ranges) {
+      foreach ($ranges as $key => $range) {
+        if ($range[1] == PHP_INT_MAX) {
+          $ranges[$key][1] = null;
+        }
+      }
+
+      $object_ranges[$phid] = new PhrequentTimeSlices(
+        $phid,
+        isset($object_ongoing[$phid]),
+        $ranges);
+    }
+
+    // Reorder the ranges to be more stack-like, so the first item is the
+    // top of the stack.
+    $object_ranges = array_reverse($object_ranges, $preserve_keys = true);
+
     return $object_ranges;
   }
 
@@ -189,33 +214,22 @@
    * Returns the current list of work.
    */
   public function getCurrentWorkStack($now, $include_inactive = false) {
-    $ranges = $this->getObjectTimeRanges($now);
+    $ranges = $this->getObjectTimeRanges();
 
     $results = array();
-    foreach ($ranges as $phid => $blocks) {
-      $total = 0;
-      foreach ($blocks as $block) {
-        $total += $block[1] - $block[0];
-      }
-
-      $type = 'inactive';
-      foreach ($blocks as $block) {
-        if ($block[1] === $now) {
-          if ($block[0] === $block[1]) {
-            $type = 'suspended';
-          } else {
-            $type = 'active';
-          }
-          break;
+    $active = null;
+    foreach ($ranges as $phid => $slices) {
+      if (!$include_inactive) {
+        if (!$slices->getIsOngoing()) {
+          continue;
         }
       }
 
-      if ($include_inactive || $type !== 'inactive') {
-        $results[] = array(
-          'phid' => $phid,
-          'time' => $total,
-          'type' => $type);
-      }
+      $results[] = array(
+        'phid' => $phid,
+        'time' => $slices->getDuration($now),
+        'ongoing' => $slices->getIsOngoing(),
+      );
     }
 
     return $results;
diff --git a/src/applications/phrequent/storage/PhrequentTimeSlices.php b/src/applications/phrequent/storage/PhrequentTimeSlices.php
new file mode 100644
--- /dev/null
+++ b/src/applications/phrequent/storage/PhrequentTimeSlices.php
@@ -0,0 +1,37 @@
+<?php
+
+final class PhrequentTimeSlices extends Phobject {
+
+  private $objectPHID;
+  private $isOngoing;
+  private $ranges;
+
+  public function __construct($object_phid, $is_ongoing, array $ranges) {
+    $this->objectPHID = $object_phid;
+    $this->isOngoing = $is_ongoing;
+    $this->ranges = $ranges;
+  }
+
+  public function getObjectPHID() {
+    return $this->objectPHID;
+  }
+
+  public function getDuration($now) {
+    foreach ($this->ranges as $range) {
+      if ($range[1] === null) {
+        return $now - $range[0];
+      } else {
+        return $range[1] - $range[0];
+      }
+    }
+  }
+
+  public function getIsOngoing() {
+    return $this->isOngoing;
+  }
+
+  public function getRanges() {
+    return $this->ranges;
+  }
+
+}
diff --git a/src/applications/phrequent/storage/__tests__/PhrequentTimeBlockTestCase.php b/src/applications/phrequent/storage/__tests__/PhrequentTimeBlockTestCase.php
--- a/src/applications/phrequent/storage/__tests__/PhrequentTimeBlockTestCase.php
+++ b/src/applications/phrequent/storage/__tests__/PhrequentTimeBlockTestCase.php
@@ -86,7 +86,9 @@
 
     $block = new PhrequentTimeBlock(array($event));
 
-    $ranges = $block->getObjectTimeRanges(1800);
+    $ranges = $block->getObjectTimeRanges();
+    $ranges = $this->reduceRanges($ranges);
+
     $this->assertEqual(
       array(
         'T1' => array(
@@ -107,7 +109,9 @@
 
     $block = new PhrequentTimeBlock(array($event));
 
-    $ranges = $block->getObjectTimeRanges(1000);
+    $ranges = $block->getObjectTimeRanges();
+    $ranges = $this->reduceRanges($ranges);
+
     $this->assertEqual(
       array(
         'T2' => array(
@@ -150,7 +154,9 @@
 
     $block = new PhrequentTimeBlock(array($event));
 
-    $ranges = $block->getObjectTimeRanges(1800);
+    $ranges = $block->getObjectTimeRanges();
+    $ranges = $this->reduceRanges($ranges);
+
     $this->assertEqual(
       array(
         'T1' => array(
@@ -172,7 +178,8 @@
 
     $block = new PhrequentTimeBlock(array($event));
 
-    $ranges = $block->getObjectTimeRanges(1000);
+    $ranges = $block->getObjectTimeRanges();
+    $ranges = $this->reduceRanges($ranges);
 
     $this->assertEqual(
       array(
@@ -198,7 +205,8 @@
 
     $block = new PhrequentTimeBlock(array($event));
 
-    $ranges = $block->getObjectTimeRanges(1000);
+    $ranges = $block->getObjectTimeRanges();
+    $ranges = $this->reduceRanges($ranges);
 
     $this->assertEqual(
       array(
@@ -213,6 +221,67 @@
       $ranges);
   }
 
+  public function testOngoing() {
+    $event = $this->newEvent('T1', 1, null);
+    $event->attachPreemptingEvents(array());
+
+    $block = new PhrequentTimeBlock(array($event));
+
+    $ranges = $block->getObjectTimeRanges();
+    $ranges = $this->reduceRanges($ranges);
+
+    $this->assertEqual(
+      array(
+        'T1' => array(
+          array(1, null),
+        ),
+      ),
+      $ranges);
+  }
+
+  public function testOngoingInterrupted() {
+    $event = $this->newEvent('T1', 1, null);
+    $event->attachPreemptingEvents(
+      array(
+        $this->newEvent('T2', 100, 900),
+      ));
+
+    $block = new PhrequentTimeBlock(array($event));
+
+    $ranges = $block->getObjectTimeRanges();
+    $ranges = $this->reduceRanges($ranges);
+
+    $this->assertEqual(
+      array(
+        'T1' => array(
+          array(1, 100),
+          array(900, null)
+        ),
+      ),
+      $ranges);
+  }
+
+  public function testOngoingPreempted() {
+    $event = $this->newEvent('T1', 1, null);
+    $event->attachPreemptingEvents(
+      array(
+        $this->newEvent('T2', 100, null),
+      ));
+
+    $block = new PhrequentTimeBlock(array($event));
+
+    $ranges = $block->getObjectTimeRanges();
+    $ranges = $this->reduceRanges($ranges);
+
+    $this->assertEqual(
+      array(
+        'T1' => array(
+          array(1, 100),
+        ),
+      ),
+      $ranges);
+  }
+
   private function newEvent($object_phid, $start_time, $end_time) {
     static $id = 0;
 
@@ -223,4 +292,14 @@
       ->setDateEnded($end_time);
   }
 
+  private function reduceRanges(array $ranges) {
+    $results = array();
+
+    foreach ($ranges as $phid => $slices) {
+      $results[$phid] = $slices->getRanges();
+    }
+
+    return $results;
+  }
+
 }