diff --git a/checkin_notes b/checkin_notes
index b6bb733a58..5ba78388e9 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -10182,3 +10182,22 @@ David  30 Oct 2007
             forum_thread.php
             account_finish_action.php
             account_finish.php
+
+David  30 Oct 2007
+    - initial checkin for Bolt
+
+    db/
+        bolt_constraints.sql
+        bolt_db.sql
+    html/
+        inc/
+            bolt.inc
+            bolt_db.inc
+            bolt_ex.inc
+            bossa_db.inc
+        ops/
+            bolt_setup_sample.php
+        user/
+            bolt.php
+            bolt_course_sample.php
+            bolt_sched.php
diff --git a/db/bolt_constraints.sql b/db/bolt_constraints.sql
new file mode 100644
index 0000000000..56db94c362
--- /dev/null
+++ b/db/bolt_constraints.sql
@@ -0,0 +1,8 @@
+alter table bolt_course
+    add unique(name);
+
+alter table bolt_enrollment
+    add unique(user_id, course_id);
+
+alter table bolt_view
+    add index bv_cs(course_id, start_time);
diff --git a/db/bolt_schema.sql b/db/bolt_schema.sql
new file mode 100644
index 0000000000..6b4433b43f
--- /dev/null
+++ b/db/bolt_schema.sql
@@ -0,0 +1,26 @@
+create table bolt_course (
+    id              integer         not null auto_increment,
+    create_time     integer         not null,
+    short_name      varchar(255)    not null,
+    name            varchar(255)    not null,
+    description     text            not null,
+    doc_file        varchar(255)    not null,
+    primary key (id)
+);
+
+create table bolt_enrollment (
+    create_time     integer         not null,
+    user_id         integer         not null,
+    course_id       integer         not null,
+    state           text            not null
+);
+
+create table bolt_view (
+    id              integer         not null auto_increment,
+    user_id         integer         not null,
+    course_id       integer         not null,
+    item_name       varchar(255)    not null,
+    start_time      integer         not null,
+    end_time        integer         not null,
+    primary key (id)
+);
diff --git a/html/inc/bolt.inc b/html/inc/bolt.inc
new file mode 100644
index 0000000000..d120970981
--- /dev/null
+++ b/html/inc/bolt.inc
@@ -0,0 +1,185 @@
+<?php
+
+error_reporting(E_ALL);
+ini_set('display_startup_errors', true);
+
+// rules about course structures:
+//
+// - Each unit has a logical name.
+// - The members of a set must have distinct logical names
+// - Different units may have the same logical name;
+//   however, such units should be identical.
+
+class BoltFrame {
+    public $state;
+        // a data structure that's specific to the unit type,
+        // e.g. a loop counter
+        // Typically this includes the logical name of the current child.
+        // Normally this is implied by the state;
+        // however, it may differ if the course structure has changed.
+        // In general the unit should restart in this case
+    function __construct($state=null) {
+        $this->state = $state;
+    }
+}
+
+abstract class BoltUnit {
+    public $name;   // logical name.
+
+    abstract function walk($old_stack, &$new_stack, $next, &$item);
+        // multi-purpose function for traversing a course.
+        // if $old_stack is null
+        //      set up initial state for this unit.
+        //      append frames to $new_stack for this unit and descendants
+        //      $next is ignored
+        //      $item is the initial item
+        //      return is ignored
+        // else
+        //      The first frame of $old_stack is for this unit.
+        //      Check for name mismatch (if changed course).
+        //      Append frames to $new_stack for this unit and descendants
+        //      if $next, the bottom-level non-item unit should increment.
+        //      return value: true if the caller should increment
+    abstract function is_item();
+}
+
+// An iterator represents a user's position in a course.
+// It is stored in the database, and the course may change underneath it.
+//
+class BoltIter {
+    public $stack;      // array of BoltFrame
+    public $top;
+
+    // point to the start of a course; set up stack.
+    //
+    function __construct($top) {
+        $this->top = $top;
+        $this->stack = null;
+    }
+
+    // get current item
+    //
+    function at() {
+        $new_stack = array();
+        $this->top->walk($this->stack, $new_stack, false, $item);
+        $this->stack = $new_stack;
+        return $item;
+    }
+
+    // move to the next item (and return it)
+    // return true if we're off the end
+    //
+    function next() {
+        $item = null;
+        $new_stack = array();
+        $this->top->walk($this->stack, $new_stack, true, $item);
+        $this->stack = $new_stack;
+        return $item;
+    }
+}
+
+class BoltSeq extends BoltUnit {
+    public $units;
+    function __construct($n, $u) {
+        $this->name = $n;
+        $this->units = $u;
+    }
+
+    function walk($old_stack, &$new_stack, $next, &$item) {
+        //echo "call to walk() for $this->name: next: $next\n";
+        if ($old_stack) {
+            //echo "old stack: \n";
+            //var_dump($old_stack);
+            //echo "------------\n";
+            $frame = $old_stack[0];
+            $state = $frame->state;
+            $i = $state->i;
+            $restart = false;
+            if ($i >= count($this->units)) {
+                echo "index too large - restarting\n";
+                $restart = true;
+            }
+            $child = $this->units[$i];
+            if ($state->child_name != $child->name) {
+                echo "bad name - restarting\n";
+                $restart = true;
+            }
+            if (!$restart) {
+                if ($next) {
+                    $inc = false;
+                    if ($child->is_item()) {
+                        $inc = true;
+                    } else {
+                        array_shift($old_stack);
+                        $inc = $child->walk($old_stack, $new_stack, true, &$item);
+                    }
+                    if ($inc) {
+                        $i++;
+                        if ($i == count($this->units)) {
+                            return true;
+                        }
+                    }
+                }
+            }
+        } else {
+            $restart = true;
+        }
+        if ($restart) {
+            $i = 0;
+        }
+        $child = $this->units[$i];
+        $state->i = $i;
+        $state->child_name = $child->name;
+        $frame = new BoltFrame($state);
+        $new_stack[] = $frame;
+        if ($child->is_item()) {
+            $item = $child;
+        } else {
+            $child->walk(null, $new_stack, false, $item);
+        }
+    }
+    function is_item() {
+        return false;
+    }
+}
+
+class BoltItem extends BoltUnit {
+    public $filename;
+    function __construct($name, $filename) {
+        $this->filename = $filename;
+        $this->name = $name;
+    }
+    function begin() {
+        return array(new BoltFrame($this));
+    }
+    function unit_list() {
+        return array(&$this);
+    }
+    function is_item() {
+        return true;
+    }
+    function walk($old_stack, &$new_stack, $next, &$item) {
+        echo "SHOULDN'T BE HERE\n";
+    }
+}
+
+class BoltLesson extends BoltItem {
+}
+
+class BoltExercise extends BoltItem {
+}
+
+function enum_course($course) {
+    $iter = new BoltIter($course);
+    while (1) {
+        $x = $iter->at();
+        if (!$x) break;
+        echo "at: $x->url\n";
+        $x = $iter->next();
+        if (!$x) break;
+        echo "next: $x->filename\n";
+    }
+    echo "course over\n";
+}
+
+?>
diff --git a/html/inc/bolt_db.inc b/html/inc/bolt_db.inc
new file mode 100644
index 0000000000..83b7c3896b
--- /dev/null
+++ b/html/inc/bolt_db.inc
@@ -0,0 +1,86 @@
+<?php
+
+require_once("../inc/db_conn.inc");
+require_once("../inc/util.inc");
+
+class BoltDb extends DbConn {
+    public static $instance;
+
+    static function get() {
+        if (!isset($instance)) {
+            $config = get_config();
+            $user = parse_config($config, '<bolt_db_user>');
+            $passwd = parse_config($config, '<bolt_db_passwd>');
+            $host = parse_config($config, '<bolt_db_host>');
+            $name = parse_config($config, '<bolt_db_name>');
+            if ($host == null) {
+                $host = "localhost";
+            }
+            $instance = new DbConn();
+            $retval = $instance->init_conn($user, $passwd, $host, $name);
+            if (!$retval) return null;
+        }
+        return $instance;
+    }
+}
+
+class BoltCourse {
+    function insert() {
+        $db = BoltDb::get();
+        $now = time();
+        $query = "insert into DBNAME.bolt_course (create_time, short_name, name, description, doc_file) values ($now, '$this->short_name', '$this->name', '$this->description', '$this->doc_file')";
+        $result = $db->do_query($query);
+        if (!$result) return false;
+        $this->id = $db->insert_id();
+        return true;
+    }
+
+    static function lookup_id($id) {
+        $db = BoltDb::get();
+        return $db->lookup_id($id, 'bolt_course', 'BoltCourse');
+    }
+
+    static function enum() {
+        $db = BoltDb::get();
+        return $db->enum('bolt_course', 'BoltCourse');
+    }
+}
+
+class BoltEnrollment {
+    function insert() {
+        $db = BoltDb::get();
+        $now = time();
+        $query = "insert into DBNAME.bolt_enrollment (create_time, user_id, course_id) values ($now, $this->user_id, $this->course_id)";
+        return $db->do_query($query);
+    }
+    function lookup($userid, $courseid) {
+        $db = BoltDb::get();
+        return $db->lookup('bolt_enrollment', 'BoltEnrollment', "user_id=$userid and course_id=$courseid");
+    }
+    function update_aux($clause) {
+        $db = BoltDb::get();
+        $db->update_aux('bolt_enrollment', $clause);
+    }
+}
+
+class BoltView {
+    function insert() {
+        $db = BoltDb::get();
+        $now = time();
+        $query = "insert into DBNAME.bolt_view (user_id, course_id, item_name, start_time) values ($this->user_id, $this->course_id, '$this->item_name', $now)";
+        $result = $db->do_query($query);
+        if (!$result) return false;
+        $this->id = $db->insert_id();
+        return true;
+    }
+    static function lookup_id($id) {
+        $db = BoltDb::get();
+        return $db->lookup_id($id, 'bolt_view', 'BoltView');
+    }
+    function update($clause) {
+        $db = BoltDb::get();
+        $db->update($this, 'bolt_view', $clause);
+    }
+}
+
+?>
diff --git a/html/inc/bolt_ex.inc b/html/inc/bolt_ex.inc
new file mode 100644
index 0000000000..357dbf56f3
--- /dev/null
+++ b/html/inc/bolt_ex.inc
@@ -0,0 +1,8 @@
+<?php
+
+function bolt_exclusive_choice($choices) {
+    foreach ($choices as $choice) {
+        echo "<br><input name=q type=radio> $choice";
+    }
+}
+?>
diff --git a/html/inc/bossa_db.inc b/html/inc/bossa_db.inc
index fc1f15044c..e1ede7bc56 100644
--- a/html/inc/bossa_db.inc
+++ b/html/inc/bossa_db.inc
@@ -1,17 +1,23 @@
 <?php
 
 require_once("../inc/db_conn.inc");
+require_once("../inc/util.inc");
 
 class BossaDb extends DbConn {
     public static $instance;
 
     static function get() {
         if (!isset($instance)) {
+            $config = get_config();
+            $user = parse_config($config, '<bossa_db_user>');
+            $passwd = parse_config($config, '<bossa_db_passwd>');
+            $host = parse_config($config, '<bossa_db_host>');
+            $name = parse_config($config, '<bossa_db_name>');
+            if ($host == null) {
+                $host = "localhost";
+            }
             $instance = new DbConn();
-            $retval = $instance->init_conn(
-                "<bossa_db_user>", "<bossa_db_passwd>",
-                "<bossa_db_host>", "<bossa_db_name>"
-            );
+            $retval = $instance->init_conn($user, $passwd, $host, $name);
             if (!$retval) return null;
         }
         return $instance;
diff --git a/html/ops/bolt_setup_sample.php b/html/ops/bolt_setup_sample.php
new file mode 100644
index 0000000000..08081108b3
--- /dev/null
+++ b/html/ops/bolt_setup_sample.php
@@ -0,0 +1,17 @@
+<?php
+
+require_once("../inc/bolt_db.inc");
+
+$c = new BoltCourse();
+$c->short_name = 'test_course';
+$c->name = 'A test course';
+$c->description = 'This course is a demonstration of Bolt';
+$c->doc_file = 'bolt_course_sample.php';
+
+if ($c->insert()) {
+    echo "all done\n";
+} else {
+    echo "database error\n";
+}
+
+?>
diff --git a/html/user/bolt.php b/html/user/bolt.php
new file mode 100644
index 0000000000..d01c7c01c8
--- /dev/null
+++ b/html/user/bolt.php
@@ -0,0 +1,25 @@
+<?php
+
+require_once("../inc/bolt_db.inc");
+require_once("../inc/util.inc");
+
+page_head("Courses");
+
+$user = get_logged_in_user(true);
+
+$courses = BoltCourse::enum();
+foreach ($courses as $course) {
+    $e = BoltEnrollment::lookup($user->id, $course->id);
+    echo "$course->name <a href=bolt_sched.php?course_id=$course->id&action=start>start</a>
+    ";
+    if ($e) {
+        echo "<a href=bolt_sched.php?course_id=$course->id>resume</a>
+        ";
+    }
+    echo "
+        <dd>$course->description
+    ";
+}
+page_tail();
+
+?>
diff --git a/html/user/bolt_course_sample.php b/html/user/bolt_course_sample.php
new file mode 100644
index 0000000000..483d12176a
--- /dev/null
+++ b/html/user/bolt_course_sample.php
@@ -0,0 +1,18 @@
+<?php
+
+return new BoltSeq(
+    'course',
+    array(
+        new BoltLesson('lesson 1', 'bolt_sample_lesson1.php'),
+        new BoltLesson('lesson 2', 'bolt_sample_lesson2.php'),
+        new BoltExercise('exercise 1', 'bolt_sample_exercise1.php'),
+        new BoltSeq(
+            'inner seq',
+            array(
+                new BoltLesson('lesson 3', 'bolt_sample_lesson3.php')
+            )
+        )
+    )
+);
+
+?>
diff --git a/html/user/bolt_sched.php b/html/user/bolt_sched.php
new file mode 100644
index 0000000000..cbf4749825
--- /dev/null
+++ b/html/user/bolt_sched.php
@@ -0,0 +1,79 @@
+<?php
+
+// Bolt scheduler.  POST args:
+// course_id: course ID
+// action:
+//      'show' or none: show current (or first) item
+//      'next': go to next lesson
+// answers:
+//      JSON represenation of exercise answers
+
+require_once("../inc/bolt.inc");
+require_once("../inc/bolt_db.inc");
+require_once("../inc/util.inc");
+
+$user = get_logged_in_user();
+$course_id = get_int('course_id');
+$view_id = get_int('view_id', true);
+$action = get_str('action', true);
+
+$course = BoltCourse::lookup_id($course_id);
+if (!$course) {
+    error_page("no such course");
+}
+
+$course_doc = require_once($course->doc_file);
+
+if ($view_id) {
+    $view = BoltView::lookup_id($view_id);
+    if ($view && $view->user_id == $user->id && !$view->end_time) {
+        $now = time();
+        $view->update("end_time=$now");
+    }
+}
+
+$e = BoltEnrollment::lookup($user->id, $course_id);
+
+if ($e) {
+    $iter = new BoltIter($course_doc);
+    $iter->stack = json_decode($e->state);
+    if ($action == 'next') {
+        $item = $iter->next();
+        $state = json_encode($iter->stack);
+        $e->update_aux("state='$state' where user_id=$user->id and course_id=$course_id");
+    } else if ($action == 'start') {
+        $iter->stack = null;
+        $item = $iter->at();
+        $state = json_encode($iter->stack);
+        $e->update_aux("state='$state' where user_id=$user->id and course_id=$course_id");
+    } else {
+        $item = $iter->at();
+    }
+} else {
+    $iter = new BoltIter($course_doc);
+    $item = $iter->at();
+
+    $e = new BoltEnrollment($course);
+    $e->user_id = $user->id;
+    $e->course_id = $course_id;
+    $e->state = json_encode($iter->stack);
+    $e->insert();
+}
+
+if (!$item) {
+    page_head("Done with course");
+    echo "All done!";
+    page_tail();
+    exit();
+}
+
+$view = new BoltView();
+$view->user_id = $user->id;
+$view->course_id = $course_id;
+$view->item_name = $item->name;
+$view->insert();
+
+require_once($item->filename);
+
+echo "<p><a href=bolt_sched.php?course_id=$course_id&action=next&view_id=$view->id>Next</a>";
+?>