On an Elgg comment, bump the original "create" river item to the top instead of adding a separate river item.

river_bump.php

<?php

elgg_register_plugin_hook_handler('creating', 'river', function ($h, $t, $v, $p) {
	$time = time();

	// Bump "create" river item to top
	// @todo should bump other action_types?
	$dbprefix = elgg_get_config('dbprefix');
	update_data("
		UPDATE {$dbprefix}river
		SET posted = $time
		WHERE action_type = 'create'
		  AND object_guid = {$v['object_guid']}
  	");

	update_entity_last_action($v['object_guid'], $time);

	// cancel create comment action
	return false;
});

river_bump_pr365.php

<?php
/**
 * Note: This is for the ElggComment patch https://github.com/Elgg/Elgg/pull/365/files
 */
elgg_register_plugin_hook_handler('creating', 'river', function ($h, $t, $v, $p) {
	$time = time();

	if ($v['type'] !== 'object' || $v['subtype'] !== 'comment') {
		return true;
	}
	
	$comment = get_entity($v['object_guid']);
	/* @var \ElggComment $comment */
	if (!$comment) {
		return true;
	}
	
	$object_guid = $comment->container_guid;
	if (!$object_guid) {
		return true;
	}
	
	// Bump "create" river item to top
	// @todo should bump other action_types?
	$dbprefix = elgg_get_config('dbprefix');
	update_data("
		UPDATE {$dbprefix}river
		SET posted = $time
		WHERE action_type = 'create'
		  AND object_guid = $object_guid
	  ");
	
	update_entity_last_action($object_guid, $time);
	
	// cancel create comment action
	return false;
});

Not really feeling this, unfortunately, because this makes the river lie about when items were created.

We definitely need a new column. I'm working around by generating the timestamp from the river item object time_created if the river item is a "create". :/

<?php
if ($river_item->action_type === 'create') {
    if ($river_obj = $river_item->getObjectEntity()) {
        $timestamp = elgg_view_friendly_time($river_obj->time_created);
    }
} else {
    $timestamp = elgg_view_friendly_time($river_item->getPostedTime());
}

Another hack: bump the river item id and ORDER BY id DESC