fix: resolve 5 open bugs (#92, #94, #95, #100, #101)

- #92: Replace MySQL-only GET_LOCK with db-agnostic locking — adds
  PostgreSQL pg_advisory_lock and timestamp-based fallback
- #94: retryFailed() now includes permanently_failed and cancelled
  statuses, not just failed
- #95: Validate scheduled_at datetime via Factory::getDate() in both
  PostModel::prepareTable() and PostsController::schedule()
- #100: Add clarifying comment to update SQL for duplicate table def
- #101: Replace fragile LIKE query with JSON_EXTRACT() for evergreen
  article detection

Authored-by: Moko Consulting
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/packages/com_mokojoomcross/sql/updates/mysql/01.01.00.sql

@@ -1,6 +1,7 @@
 -- MokoJoomCross 01.01.00 — Category routing rules
 -- Copyright (C) 2026 Moko Consulting. All rights reserved.
 -- SPDX-License-Identifier: GPL-3.0-or-later
+-- Note: also in install.mysql.sql for fresh installs; IF NOT EXISTS prevents conflicts
 
 CREATE TABLE IF NOT EXISTS `#__mokojoomcross_category_rules` (
     `id` int(10) unsigned NOT NULL AUTO_INCREMENT,

src/packages/com_mokojoomcross/src/Controller/PostsController.php

@@ -55,6 +55,18 @@ class PostsController extends AdminController
             return;
         }
 
+        try {
+            $scheduledDate = Factory::getDate($scheduledAt);
+            $scheduledAt   = $scheduledDate->toSql();
+        } catch (\Throwable $e) {
+            $this->setRedirect(
+                Route::_('index.php?option=com_mokojoomcross&view=posts', false),
+                Text::_('COM_MOKOJOOMCROSS_SCHEDULE_INVALID_DATE'),
+                'error'
+            );
+            return;
+        }
+
         $db  = Factory::getDbo();
         $now = Factory::getDate()->toSql();
 
@@ -123,7 +135,7 @@ class PostsController extends AdminController
             ->set($db->quoteName('retry_count') . ' = 0')
             ->set($db->quoteName('error_message') . ' = ' . $db->quote(''))
             ->set($db->quoteName('modified') . ' = ' . $db->quote(Factory::getDate()->toSql()))
-            ->where($db->quoteName('status') . ' = ' . $db->quote('failed'));
+            ->where($db->quoteName('status') . ' IN (' . $db->quote('failed') . ',' . $db->quote('permanently_failed') . ',' . $db->quote('cancelled') . ')');
 
         $db->setQuery($query);
         $db->execute();

src/packages/com_mokojoomcross/src/Helper/QueueProcessor.php

@@ -320,7 +320,7 @@ class QueueProcessor
             ->select('c.id, c.attribs')
             ->from($db->quoteName('#__content', 'c'))
             ->where($db->quoteName('c.state') . ' = 1')
-            ->where($db->quoteName('c.attribs') . ' LIKE ' . $db->quote('%"mokojoomcross_evergreen":"1"%'));
+            ->where('JSON_EXTRACT(' . $db->quoteName('c.attribs') . ', ' . $db->quote('$.mokojoomcross_evergreen') . ') = ' . $db->quote('1'));
 
         $db->setQuery($query);
         $articles = $db->loadObjectList() ?: [];
@@ -733,27 +733,111 @@ class QueueProcessor
     }
 
     /**
-     * Acquire a MySQL advisory lock to prevent concurrent queue processing.
+     * Acquire a database lock to prevent concurrent queue processing.
      *
-     * Uses GET_LOCK() which is atomic — no race condition possible.
-     * The 0 timeout means non-blocking (returns immediately if lock is held).
-     * MySQL automatically releases the lock if the connection drops.
+     * Uses MySQL GET_LOCK() or PostgreSQL pg_advisory_lock() when available,
+     * falling back to a timestamp-based check for other databases.
      */
     private static function acquireLock(): bool
     {
         $db = Factory::getDbo();
-        $db->setQuery("SELECT GET_LOCK('mokojoomcross_queue', 0)");
 
-        return (int) $db->loadResult() === 1;
+        try {
+            $serverType = $db->getServerType();
+
+            if ($serverType === 'mysql' || $serverType === 'mariadb') {
+                $db->setQuery("SELECT GET_LOCK('mokojoomcross_queue', 0)");
+
+                return (int) $db->loadResult() === 1;
+            }
+
+            if ($serverType === 'postgresql') {
+                $db->setQuery("SELECT pg_try_advisory_lock(hashtext('mokojoomcross_queue'))");
+
+                return (bool) $db->loadResult();
+            }
+        } catch (\Throwable $e) {
+            // Fall through to timestamp-based lock
+        }
+
+        return self::acquireTimestampLock($db);
     }
 
     /**
-     * Release the MySQL advisory lock.
+     * Release the database lock.
      */
     private static function releaseLock(): void
     {
         $db = Factory::getDbo();
-        $db->setQuery("SELECT RELEASE_LOCK('mokojoomcross_queue')");
+
+        try {
+            $serverType = $db->getServerType();
+
+            if ($serverType === 'mysql' || $serverType === 'mariadb') {
+                $db->setQuery("SELECT RELEASE_LOCK('mokojoomcross_queue')");
+                $db->execute();
+
+                return;
+            }
+
+            if ($serverType === 'postgresql') {
+                $db->setQuery("SELECT pg_advisory_unlock(hashtext('mokojoomcross_queue'))");
+                $db->execute();
+
+                return;
+            }
+        } catch (\Throwable $e) {
+            // Fall through to timestamp-based release
+        }
+
+        self::releaseTimestampLock($db);
+    }
+
+    /**
+     * Timestamp-based lock fallback for databases without advisory locks.
+     *
+     * Uses the component params to store a lock timestamp. Considers the lock
+     * stale after 120 seconds to prevent deadlocks from crashed processes.
+     */
+    private static function acquireTimestampLock($db): bool
+    {
+        $params = ComponentHelper::getParams('com_mokojoomcross');
+        $lockTime = (int) $params->get('queue_lock_time', 0);
+        $now = time();
+
+        if ($lockTime > 0 && ($now - $lockTime) < 120) {
+            return false;
+        }
+
+        $params->set('queue_lock_time', $now);
+
+        $query = $db->getQuery(true)
+            ->update($db->quoteName('#__extensions'))
+            ->set($db->quoteName('params') . ' = ' . $db->quote($params->toString()))
+            ->where($db->quoteName('element') . ' = ' . $db->quote('com_mokojoomcross'))
+            ->where($db->quoteName('type') . ' = ' . $db->quote('component'));
+
+        $db->setQuery($query);
+        $db->execute();
+
+        return true;
+    }
+
+    /**
+     * Release the timestamp-based lock.
+     */
+    private static function releaseTimestampLock($db): void
+    {
+        $params = ComponentHelper::getParams('com_mokojoomcross');
+        $params->set('queue_lock_time', 0);
+
+        $query = $db->getQuery(true)
+            ->update($db->quoteName('#__extensions'))
+            ->set($db->quoteName('params') . ' = ' . $db->quote($params->toString()))
+            ->where($db->quoteName('element') . ' = ' . $db->quote('com_mokojoomcross'))
+            ->where($db->quoteName('type') . ' = ' . $db->quote('component'));
+
+        $db->setQuery($query);
         $db->execute();
     }
 

src/packages/com_mokojoomcross/src/Model/PostModel.php

@@ -53,6 +53,16 @@ class PostModel extends AdminModel
     {
         $now = Factory::getDate()->toSql();
 
+        // Validate scheduled_at datetime format
+        if (!empty($table->scheduled_at)) {
+            try {
+                $date = Factory::getDate($table->scheduled_at);
+                $table->scheduled_at = $date->toSql();
+            } catch (\Throwable $e) {
+                $table->scheduled_at = null;
+            }
+        }
+
         if (empty($table->id)) {
             $table->created  = $now;
             $table->modified = $now;