Answered how to set public read access for attachments

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class DiscussAttachmentDownloadController extends DiscussController {
    public function getPageTitle() {

    }
    public function getSessionPlace() {
        return 'attachment/download:file='.$this->getProperty('file','');
    }

    public function process() {
        $file = $this->getProperty('file',false);
        /* get attachment */

/* setup basic settings/permissions */
$dateFormat = $modx->getOption('discuss.date_format',null,'%b %d, %Y, %H:%M %p');
$allowCustomTitles = $modx->getOption('discuss.allow_custom_titles',null,true);
$maxPostDepth = $modx->getOption('discuss.max_post_depth',null,3);

$canViewAttachments = $modx->hasPermission('discuss.view_attachments');
$canTrackIp = $discuss->user->isLoggedIn && $modx->hasPermission('discuss.track_ip');
$canViewEmails = $discuss->user->isLoggedIn && $modx->hasPermission('discuss.view_emails');
$canViewProfiles = $discuss->user->isLoggedIn && $modx->hasPermission('discuss.view_profiles');
$canReportPost = $discuss->user->isLoggedIn && $modx->hasPermission('discuss.thread_report');
$canMarkAsAnswer = $thread->get('class_key') == 'disThreadQuestion' && $thread->canMarkAsAnswer();