Only purge page caches when enabling object cache to preserve session/auth

- Add purge_page_caches() to purge File/Browser caches without flushing object cache
- Refactor purge_all() to use purge_page_caches() then flush object cache
- When enabling object cache, call purge_page_caches() only to avoid logging out user
- When disabling object cache, call purge_all() to clear everything

Author: arunshenoy99

includes/Cache/CachePurgingService.php

@@ -90,9 +90,10 @@ public function manual_purge_request() {
 	}
 
 	/**
-	 * Purge everything.
+	 * Purge page caches only (File, Browser). Does not flush object cache.
+	 * Use when enabling object cache so session/auth data is not flushed.
 	 */
-	public function purge_all() {
+	public function purge_page_caches() {
 		foreach ( $this->cache_types as $instance ) {
 			if ( array_key_exists( Purgeable::class, class_implements( $instance ) ) ) {
 				/**
@@ -103,6 +104,13 @@ public function purge_all() {
 				$instance->purge_all();
 			}
 		}
+	}
+
+	/**
+	 * Purge everything (page caches and object cache).
+	 */
+	public function purge_all() {
+		$this->purge_page_caches();
 		ObjectCache::flush_object_cache();
 	}
 

includes/RestApi/CacheController.php

@@ -130,8 +130,14 @@ public function update_settings( \WP_REST_Request $request ) {
 					$out = ObjectCache::disable();
 				}
 				if ( $out['success'] ) {
-					// Purge page cache and object cache (purge_all includes flush_object_cache).
-					container()->get( 'cachePurger' )->purge_all();
+					// When enabling: only purge page caches so we don't flush object cache (avoids logging out the user).
+					// When disabling: purge everything including object cache.
+					$purger = container()->get( 'cachePurger' );
+					if ( $enable ) {
+						$purger->purge_page_caches();
+					} else {
+						$purger->purge_all();
+					}
 					return new \WP_REST_Response( array( 'result' => true ), 200 );
 				}
 				return new \WP_REST_Response(