Was integrating MDL-55000, first amd module belonging to a subsystem, apparently, when I detected that it was not using proper component name but just the subsystem name.

So things like this was working:

$PAGE->requires->js_call_amd('grades/edittree_index', 'enhance');

But this was not (and is the correct one):

$PAGE->requires->js_call_amd('core_grades/edittree_index', 'enhance');

Finally, curiously using it in a -lazy way, was working ok with correct component name:

$PAGE->requires->js_call_amd('core_grades/edittree_index-lazy', 'enhance');

Following the code, the problem seems to be @ lib/classes/requirejs.php where the directories for subsystems are added by name, not by component. I just applied ths quick and dirty hack and then 'core_grades' started to work:

diff --git a/lib/classes/requirejs.php b/lib/classes/requirejs.php

index 9894dc5..ebe4e6f 100644

--- a/lib/classes/requirejs.php

+++ b/lib/classes/requirejs.php

@@ -90,7 +90,7 @@ class core_requirejs {

         $subsystems = core_component::get_core_subsystems();

         foreach ($subsystems as $subsystem => $dir) {

             if (!empty($dir) && is_dir($dir . '/amd')) {

-                $jsdirs[$subsystem] = $dir . '/amd';

+                $jsdirs['core_' . $subsystem] = $dir . '/amd';

             }

         }

         $plugintypes = core_component::get_plugin_types();

Surely we should change it to always use correct component names, both for plugins (working already) and subsystems, covered with unit tests, before we start spreading amd modules over subsystems. That will make things work as documented (by component name) and will allow us to use correct @module, @package and js_call_amd() calls. And also will allow to move some current modules (tag....) to their corresponding subsystem.

For your consideration, ciao

PS: I'd consider this a bug at all effects.