Add atomic cache-based mutex lock to prevent concurrent import cron execution

includes/admin/feedzy-rss-feeds-import.php

@@ -1544,6 +1544,27 @@ public function run_cron( $max = 100, $job_id = 0 ) {
 
 		$feedzy_imports = get_posts( $args );
 		foreach ( $feedzy_imports as $job ) {
+			$lock_key = 'feedzy_import_lock_' . $job->ID;
+
+			// Determine lock TTL based on max execution time (plus buffer) and allow filtering.
+			$max_execution_time = (int) apply_filters( 'feedzy_max_execution_time', 500 );
+			if ( $max_execution_time <= 0 ) {
+				$max_execution_time = 300; // Fallback to 5 minutes if unlimited or not set.
+			}
+			$lock_ttl = (int) apply_filters( 'feedzy_import_lock_ttl', $max_execution_time + 60, $job );
+
+			// Atomically try to acquire lock - wp_cache_add returns false if key already exists.
+			if ( ! wp_cache_add( $lock_key, time(), 'feedzy_import_locks', $lock_ttl ) ) {
+				Feedzy_Rss_Feeds_Log::info(
+					'Skipping job: ' . $job->post_title,
+					array(
+						'job_id' => $job->ID,
+						'reason' => 'concurrent_execution_prevented',
+					)
+				);
+				continue;
+			}
+
 			try {
 				$result = $this->run_job( $job, $max );
 
@@ -1567,7 +1588,7 @@ public function run_cron( $max = 100, $job_id = 0 ) {
 					);
 				}
 				do_action( 'feedzy_run_cron_extra', $job );
-			} catch ( Exception $e ) {
+			} catch ( Throwable $e ) {
 				if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
 					error_log( '[Feedzy Run Cron][Post title: ' . ( ! empty( $job->post_title ) ? $job->post_title : '' ) . '] Error: ' . $e->getMessage() );
 				}
@@ -1580,6 +1601,9 @@ public function run_cron( $max = 100, $job_id = 0 ) {
 						'error'  => $e->getMessage(),
 					)
 				);
+			} finally {
+				// Always release the lock, even on error.
+				wp_cache_delete( $lock_key, 'feedzy_import_locks' );
 			}
 		}
 	}