fix: Separate settings groups to prevent cross-tab overwrites (v0.4.5)

Split Metrics sub-tab settings into separate WordPress option groups:
- wp_prometheus_endpoint_settings for auth token
- wp_prometheus_selection_settings for enabled metrics
- wp_prometheus_advanced_settings for isolated mode

This fixes the bug where saving from one sub-tab would clear settings
from other sub-tabs due to all settings sharing a single option group.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

wp-prometheus.php

@@ -3,7 +3,7 @@
  * Plugin Name: WP Prometheus
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wp-prometheus
  * Description: Prometheus metrics endpoint for WordPress with extensible hooks for custom metrics.
- * Version: 0.4.3
+ * Version: 0.4.5
  * Requires at least: 6.4
  * Requires PHP: 8.3
  * Author: Marco Graetsch
@@ -22,11 +22,16 @@ if ( ! defined( 'ABSPATH' ) ) {
 }
 
 /**
- * Early metrics endpoint handler.
+ * Early metrics request detection.
  *
- * Intercepts /metrics requests before full WordPress initialization to avoid
- * conflicts with other plugins that may cause issues during template loading.
- * This runs at plugin load time, before plugins_loaded hook.
+ * Detects /metrics requests early and removes problematic content filters
+ * to prevent recursion issues with Twig-based plugins. Unlike the previous
+ * "early mode", this allows WordPress to continue loading so that third-party
+ * plugins can register their wp_prometheus_collect_metrics hooks.
+ *
+ * Two modes are available:
+ * - Safe mode (default): Removes filters early, lets WP load, fires custom hooks
+ * - Isolated mode: Outputs metrics immediately without custom hooks (legacy early mode)
  */
 function wp_prometheus_early_metrics_check(): void {
     // Only handle /metrics requests.
@@ -37,18 +42,58 @@ function wp_prometheus_early_metrics_check(): void {
         return;
     }
 
-    // Check if early mode is disabled via environment variable.
-    $env_disable = getenv( 'WP_PROMETHEUS_DISABLE_EARLY_MODE' );
-    if ( false !== $env_disable && in_array( strtolower( $env_disable ), array( '1', 'true', 'yes', 'on' ), true ) ) {
-        return;
+    // Set flag to indicate we're handling a metrics request.
+    define( 'WP_PROMETHEUS_METRICS_REQUEST', true );
+
+    // Check if isolated mode is enabled via environment variable.
+    $env_isolated = getenv( 'WP_PROMETHEUS_ISOLATED_MODE' );
+    $isolated_mode = false !== $env_isolated && in_array( strtolower( $env_isolated ), array( '1', 'true', 'yes', 'on' ), true );
+
+    // Check if isolated mode is enabled via option (legacy "early mode" setting).
+    if ( ! $isolated_mode && ! get_option( 'wp_prometheus_disable_early_mode', false ) ) {
+        // Check for legacy isolated mode option.
+        $isolated_mode = (bool) get_option( 'wp_prometheus_isolated_mode', false );
     }
 
-    // Check if early mode is disabled via option.
-    // We can use get_option() here because WordPress core is already loaded.
-    if ( get_option( 'wp_prometheus_disable_early_mode', false ) ) {
-        return;
-    }
+    // Remove all content filters immediately to prevent recursion with Twig-based plugins.
+    // This is done for BOTH safe mode and isolated mode.
+    add_action( 'plugins_loaded', 'wp_prometheus_remove_content_filters', 0 );
 
+    // Also remove filters now in case they were added by mu-plugins.
+    wp_prometheus_remove_content_filters();
+
+    // If isolated mode is enabled, handle metrics immediately without waiting for plugins.
+    if ( $isolated_mode ) {
+        wp_prometheus_isolated_metrics_handler();
+    }
+}
+
+/**
+ * Remove content filters that can cause recursion.
+ *
+ * Called early during metrics requests to prevent infinite loops
+ * with Twig-based plugins that hook into content filters.
+ *
+ * @return void
+ */
+function wp_prometheus_remove_content_filters(): void {
+    remove_all_filters( 'the_content' );
+    remove_all_filters( 'the_excerpt' );
+    remove_all_filters( 'get_the_excerpt' );
+    remove_all_filters( 'the_title' );
+    remove_all_filters( 'the_content_feed' );
+    remove_all_filters( 'comment_text' );
+}
+
+/**
+ * Handle metrics in isolated mode (no custom hooks).
+ *
+ * This is the legacy "early mode" that outputs metrics immediately
+ * without allowing third-party plugins to add custom metrics.
+ *
+ * @return void
+ */
+function wp_prometheus_isolated_metrics_handler(): void {
     // Check if autoloader exists.
     $autoloader = __DIR__ . '/vendor/autoload.php';
     if ( ! file_exists( $autoloader ) ) {
@@ -99,14 +144,8 @@ function wp_prometheus_early_metrics_check(): void {
         exit;
     }
 
-    // Set flag to indicate early metrics mode - Collector will skip extensibility hooks.
-    define( 'WP_PROMETHEUS_EARLY_METRICS', true );
-
-    // Remove all content filters to prevent recursion with Twig-based plugins.
-    remove_all_filters( 'the_content' );
-    remove_all_filters( 'the_excerpt' );
-    remove_all_filters( 'get_the_excerpt' );
-    remove_all_filters( 'the_title' );
+    // Set flag to indicate isolated mode - Collector will skip extensibility hooks.
+    define( 'WP_PROMETHEUS_ISOLATED_MODE', true );
 
     // Output metrics and exit immediately.
     $collector = new \Magdev\WpPrometheus\Metrics\Collector();
@@ -130,7 +169,7 @@ wp_prometheus_early_metrics_check();
  *
  * @var string
  */
-define( 'WP_PROMETHEUS_VERSION', '0.4.3' );
+define( 'WP_PROMETHEUS_VERSION', '0.4.5' );
 
 /**
  * Plugin file path.