feat(cache): Verhaltensprobe und Smoke für WP Super Cache

SuperCacheProbe prüft beim Prüfen, ob wp_cache_post_edit die Cache-Datei einer Testseite entfernt; während der Probe ist nur der Einzelseiten-Purge erlaubt, der Pfad kommt aus home und es werden nur feste Dateinamen gelöscht. ProbeStep bündelt die Schrittlogik von Pods und WP Super Cache; ThrowawayPost hält Marker und Titel zentral und räumt auch private Probe-Seiten auf (WP Super Cache wie Pods beim Laden des Reiters). super-cache-smoke.sh prüft gegen das echte Plugin; lib.sh sperrt parallele Smoke-Läufe per flock, wp-config.php wird atomar wiederhergestellt. Doku: Host-Abhängigkeit des Einzel-Purges, WP-Cron für den Nachlauf, Komplett-Purge durch Divi beim Prüfen.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/guides/overview.md

@@ -100,6 +100,9 @@ nichts geändert. Vorgehen:
    `compat_incompatible`; der Stand steht im selben Reiter „Compatibility“.
 
 Seitenweite Änderungen (Optionen, Menüs und Menü-Positionen, Medien, Divi-Design, Theme Builder, globale
-Bibliotheksmodule) leeren den Cache von WP Super Cache, Änderungen an einem Beitrag nur dessen Seite. Ist der Cache
+Bibliotheksmodule) leeren den Cache von WP Super Cache, Änderungen an einem Beitrag nur dessen Seite. Dabei leert der
-dafür gesperrt, bleibt er unverändert; der Zustand steht im Reiter „Compatibility“ und in `lit-site-status`
+Purge eines einzelnen Beitrags die Cache-Dateien unter dem Host, über den der MCP-Aufruf eingeht; bei verschiedenen
-(`wpsc`).
+Hosts (z. B. mit und ohne `www`) bleiben die Dateien des anderen Hosts womöglich ungeleert (der Komplett-Purge ist davon
+nicht betroffen). Ist der Cache dafür gesperrt, bleibt er unverändert; der Zustand steht im Reiter „Compatibility“
+und in `lit-site-status` (`wpsc`). Der Nachlauf-Purge, der auf ein gedrosseltes Leeren des ganzen Caches folgt, braucht WP-Cron (oder einen
+System-Cron, der `wp-cron.php` aufruft).

src/Compatibility/ProbeStep.php

@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Compatibility;
+
+use Closure;
+
+defined('ABSPATH') || exit;
+
+/** The one check step a profile's behaviour probe makes (Profile::$extraSteps), shared by Pods and WP Super Cache. */
+final class ProbeStep
+{
+    /**
+     * Skipped while the manifest is red (the probe would fail anyway). A probe with nothing to probe (null) is a
+     * green step that says so, not a skipped one: a skipped step makes the report red and would lock the plugin on a
+     * site that simply has nothing to probe yet.
+     *
+     * @param Closure(): (list<string>|null) $probe Problems, [] = green, null = nothing to probe.
+     * @return Closure(bool): list<CheckStep>
+     */
+    public static function extra(string $key, string $label, string $labelNothingToProbe, Closure $probe): Closure
+    {
+        return static function (bool $manifestClean) use ($key, $label, $labelNothingToProbe, $probe): array {
+            if (! $manifestClean) {
+                return [new CheckStep($key, [], true, $label)];
+            }
+
+            $none = false;
+            $problems = CompatibilityCheck::guarded(static function () use ($probe, &$none): array {
+                $result = $probe();
+                $none = $result === null;
+
+                return $result ?? [];
+            });
+
+            return [new CheckStep($key, $problems, false, $none ? $labelNothingToProbe : $label)];
+        };
+    }
+}

src/Compatibility/ThrowawayPost.php

@@ -22,6 +22,11 @@ defined('ABSPATH') || exit;
  */
 final class ThrowawayPost
 {
+    /** Meta key and title prefix the Pods and WP Super Cache probes give their entries (the Divi write probe has its own). */
+    public const MARKER = '_lit_mcp_check_entry';
+
+    public const TITLE = '[LIT MCP Prüfung]';
+
     /** Only entries not modified for this long are orphans – a running check's entry is younger. */
     private const ORPHAN_AGE_SECONDS = 600;
 
@@ -68,14 +73,14 @@ final class ThrowawayPost
 
     /**
      * @param array<int, string>|string $postTypes
-     * @return list<int> IDs of entries a dead check left behind, deleted now. Only drafts whose title starts with
+     * @return list<int> IDs of entries a dead check left behind, deleted now. Only drafts and private entries (a
-     *     the prefix are considered.
+     *     probe may pass through private) whose title starts with the prefix are considered.
      */
     public function removeOrphans(array|string $postTypes): array
     {
         $posts = get_posts([
             'post_type' => $postTypes,
-            'post_status' => 'draft',
+            'post_status' => ['draft', 'private'],
             // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key -- a handful of marked entries at most.
             'meta_key' => $this->marker,
             // post_modified_gmt, not post_date_gmt: an edit by the check keeps it current. A literal GMT timestamp,

src/Integrations/Divi/Release/WriteProbe.php

@@ -87,7 +87,7 @@ class WriteProbe
 
     /**
      * @return list<int> IDs of check pages a dead check left behind, deleted now (ThrowawayPost::removeOrphans():
-     *     marked drafts with the check title only).
+     *     marked drafts and private pages with the check title only).
      */
     public static function removeOrphans(): array
     {

src/Integrations/Pods/PodsCheckSteps.php

@@ -6,7 +6,7 @@ namespace LIT\MCP\Integrations\Pods;
 
 use Closure;
 use LIT\MCP\Compatibility\CheckStep;
-use LIT\MCP\Compatibility\CompatibilityCheck;
+use LIT\MCP\Compatibility\ProbeStep;
 
 defined('ABSPATH') || exit;
 
@@ -19,30 +19,15 @@ final class PodsCheckSteps
     private const LABEL_NO_TARGET = self::LABEL . ' (kein Pod mit Textfeld vorhanden, nicht geprüft)';
 
     /**
-     * The Profile::$extraSteps of Pods: the probe, skipped while the manifest is red (it would fail anyway). No pod
+     * The Profile::$extraSteps of Pods: the probe (ProbeStep: skipped on a red manifest, green with a hint when
-     * to probe (null) is a green step that says so, not a skipped one: a skipped step makes the report red and
+     * there is no pod to probe).
-     * would lock Pods on a site that simply has no pod yet.
      *
      * @param Closure(): (list<string>|null) $probe PodsProbe::run().
      * @return Closure(bool): list<CheckStep>
      */
     public static function extra(Closure $probe): Closure
     {
-        return static function (bool $manifestClean) use ($probe): array {
+        return ProbeStep::extra(self::PROBE, self::LABEL, self::LABEL_NO_TARGET, $probe);
-            if (! $manifestClean) {
-                return [new CheckStep(self::PROBE, [], true, self::LABEL)];
-            }
-
-            $none = false;
-            $problems = CompatibilityCheck::guarded(static function () use ($probe, &$none): array {
-                $result = $probe();
-                $none = $result === null;
-
-                return $result ?? [];
-            });
-
-            return [new CheckStep(self::PROBE, $problems, false, $none ? self::LABEL_NO_TARGET : self::LABEL)];
-        };
     }
 
     public static function label(CheckStep $step): string

src/Integrations/Pods/PodsProbe.php

@@ -16,7 +16,7 @@ defined('ABSPATH') || exit;
  * profile again) it loads the schema of an existing pod, writes a plain text field of a throwaway draft entry,
  * reads it back and compares. The pod and its schema are never touched (no save_pod, so no rewrite flush, no
  * schema cache change); only the entry is created and always deleted for good (ThrowawayPost). Entries a dead
- * check left behind carry MARKER; removeOrphans() deletes them. Runs only from the check route
+ * check left behind carry ThrowawayPost::MARKER; removeOrphans() deletes them. Runs only from the check route
  * (Compatibility::check).
  *
  * Target: a pod of a post type Pods created itself (pod arg 'object' empty) comes first, then a foreign type Pods
@@ -28,10 +28,6 @@ defined('ABSPATH') || exit;
  */
 final class PodsProbe
 {
-    public const MARKER = '_lit_mcp_check_entry';
-
-    public const TITLE = '[LIT MCP Prüfung]';
-
     public const VALUE = 'litcheck-pods-probe';
 
     private const ABORTED = 'Pods-Probe abgebrochen (Details im PHP-Error-Log).';
@@ -92,12 +88,12 @@ final class PodsProbe
     private static function throwaway(): ThrowawayPost
     {
         return new ThrowawayPost(
-            self::MARKER,
+            ThrowawayPost::MARKER,
-            self::TITLE,
+            ThrowawayPost::TITLE,
             self::ABORTED,
             'Der Probe-Eintrag konnte nicht angelegt werden (Details im PHP-Error-Log).',
             'Der Probe-Eintrag %d konnte nicht gelöscht werden; bitte endgültig löschen (Titel „'
-                . self::TITLE . ' …“).',
+                . ThrowawayPost::TITLE . ' …“).',
             'pods probe'
         );
     }

src/Integrations/SuperCache/SuperCacheCheckSteps.php

@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\SuperCache;
+
+use Closure;
+use LIT\MCP\Compatibility\CheckStep;
+use LIT\MCP\Compatibility\ProbeStep;
+
+defined('ABSPATH') || exit;
+
+/** The check step only WP Super Cache has (the purge probe, SuperCacheProbe) and its labels. */
+final class SuperCacheCheckSteps
+{
+    public const PROBE = 'probe';
+
+    private const LABEL = 'Leeren-Test an einer Wegwerf-Seite im Cache';
+    private const LABEL_CACHE_OFF = self::LABEL . ' (Cache ist ausgeschaltet, nicht geprüft)';
+
+    /**
+     * The Profile::$extraSteps of WP Super Cache. A switched-off cache is a green step that says so: a skipped step
+     * would lock the purge on a site that caches nothing.
+     *
+     * @param Closure(): (list<string>|null) $probe SuperCacheProbe::run().
+     * @return Closure(bool): list<CheckStep>
+     */
+    public static function extra(Closure $probe): Closure
+    {
+        return ProbeStep::extra(self::PROBE, self::LABEL, self::LABEL_CACHE_OFF, $probe);
+    }
+
+    public static function label(CheckStep $step): string
+    {
+        // Reports saved before labels were stored have none.
+        return $step->label
+            ?? ($step->key === self::PROBE ? self::LABEL : null)
+            ?? CheckStep::genericLabel($step->key, SuperCacheCompatibility::LABEL)
+            ?? $step->key;
+    }
+}

src/Integrations/SuperCache/SuperCacheCompatibility.php

@@ -18,7 +18,7 @@ defined('ABSPATH') || exit;
  * 3.1.5 (wp-cache-phase2.php). wp_cache_post_edit is no documented API: if a release drops it, only the purge is
  * locked (visible in the tab and in lit-site-status). Both functions read the global $cache_path, which wp-cache.php
  * sets on load from wp-cache-config.php or its sample; wp_cache_post_edit also reads $blog_cache_dir
- * (wp-cache-base.php).
+ * (wp-cache-base.php). The check adds a purge probe (SuperCacheProbe).
  */
 final class SuperCacheCompatibility
 {
@@ -55,7 +55,9 @@ final class SuperCacheCompatibility
 
                 return $version === '' ? null : $version;
             },
-            testedVersions: ['3.1.5']
+            testedVersions: ['3.1.5'],
+            extraSteps: SuperCacheCheckSteps::extra(static fn (): ?array => (new SuperCacheProbe())->run()),
+            stepLabel: SuperCacheCheckSteps::label(...)
         );
     }
 }

src/Integrations/SuperCache/SuperCacheIntegration.php

@@ -4,17 +4,45 @@ declare(strict_types=1);
 
 namespace LIT\MCP\Integrations\SuperCache;
 
+use LIT\MCP\Admin\CompatibilityTab;
 use LIT\MCP\Compatibility\ProvidesCompatibility;
+use LIT\MCP\Integrations\Bootable;
 use LIT\MCP\Integrations\Integration;
 
 defined('ABSPATH') || exit;
 
 /**
- * WP Super Cache has no tools: the integration only brings the compatibility profile (SuperCacheListener does the
+ * WP Super Cache has no tools: the integration brings the compatibility profile (SuperCacheListener does the
- * work, wired by Plugin). Without abilities it is no tool group.
+ * work, wired by Plugin) and the cleanup of probe pages a dead check left behind. Without abilities it is no tool
+ * group.
  */
-final class SuperCacheIntegration implements Integration, ProvidesCompatibility
+final class SuperCacheIntegration implements Integration, ProvidesCompatibility, Bootable
 {
+    /** @var callable(): bool */
+    private $available;
+
+    /** @param callable(): bool|null $available Whether WP Super Cache is loaded; null = WPCACHEHOME is defined. */
+    public function __construct(?callable $available = null)
+    {
+        $this->available = $available ?? static fn (): bool => defined('WPCACHEHOME');
+    }
+
+    public function boot(): void
+    {
+        add_action(CompatibilityTab::LOAD_ACTION, [$this, 'removeOrphans']);
+    }
+
+    /**
+     * lit_mcp_compat_profile_load('wpsc'), before any output: deletes probe pages a dead check left behind
+     * (SuperCacheProbe::removeOrphans()). A GET without nonce on purpose: only the plugin's own leftovers, idempotent.
+     */
+    public function removeOrphans(string $profileId): void
+    {
+        if ($profileId === 'wpsc' && $this->isAvailable() && current_user_can('manage_options')) {
+            SuperCacheProbe::removeOrphans();
+        }
+    }
+
     public function id(): string
     {
         return 'wpsc';
@@ -27,7 +55,7 @@ final class SuperCacheIntegration implements Integration, ProvidesCompatibility
 
     public function isAvailable(): bool
     {
-        return defined('WPCACHEHOME');
+        return ($this->available)();
     }
 
     public function abilities(): array

src/Integrations/SuperCache/SuperCacheProbe.php

@@ -0,0 +1,230 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Integrations\SuperCache;
+
+use Closure;
+use LIT\MCP\Compatibility\ThrowawayPost;
+use LIT\MCP\Log;
+use Throwable;
+
+defined('ABSPATH') || exit;
+
+/**
+ * Purge probe of the WP Super Cache check: a marked throwaway page gets a cache file at the exact place WP Super
+ * Cache keeps the cache of that page (its own path logic), wp_cache_post_edit() – what SuperCacheListener calls –
+ * runs, and the file must be gone (renamed to ".needs-rebuild" counts as gone: that is how WPSC marks it). The
+ * file, its directory and the page are always removed (ThrowawayPost). Entries a dead check left behind are
+ * deleted by removeOrphans(). The whole-cache purge (wp_cache_clear_cache) is not probed: it would empty the live
+ * cache of the site on every check. Runs only from the check route (Compatibility::check).
+ *
+ * The purge of the live site is narrowed for the call: $wp_cache_clear_on_post_edit is 0 (otherwise WPSC empties
+ * the whole cache) and the filter wpsc_delete_related_pages_on_edit returns false (otherwise wp_cache_post_change
+ * clears the home page and page/ as well); both are put back exactly, also when WPSC throws. What WPSC still does
+ * for a page then: it empties the cache directory of that page (wp_cache_post_id_gc, $all = false: no page/, no
+ * home page), deletes the legacy wp-cache meta files of that page and any unreadable legacy meta file of this site
+ * (stray files, unusable anyway), fires the action gc_cache ("prune"/"rebuild" with the page's address – other
+ * plugins hooking it, e.g. preloaders, see the probe page) and, for each public taxonomy term of the page,
+ * wpsc_delete_post_archives() clears the term archive's cache. A fresh page has no terms unless another plugin
+ * gives pages a default term; then that one archive loses its cache file on every check.
+ *
+ * NOT avoidable: creating, changing and deleting the page are real WordPress calls, and other plugins react to them
+ * like to any editor's page. Divi 5 (Loop module, LoopHooks → et_core_clear_wp_cache → wp_cache_clear_cache) empties
+ * the whole WPSC cache on every insert and delete of a page – seen on the DDEV site, so on a Divi site every check
+ * empties the live cache regardless of what the probe does itself.
+ *
+ * The page is a draft; wp_cache_post_edit skips drafts, so for the call it is a private page – its status is set
+ * straight in the database, without hooks: WPSC itself hooks clean_post_cache/edit_post to wp_cache_post_edit and
+ * remembers the last post per request, so a real status change would use up the call before the probe makes it.
+ *
+ * The cache directory is WPSC's own (get_current_url_supercache_dir), which takes the host from the request. It is
+ * used only when it is exactly <home host directory>/<probe slug>/; any other host (www or not) makes the probe
+ * "not checked" instead of looking in the wrong place.
+ *
+ * shortcut: needs a pretty permalink structure with WP in the home address' directory (WPSC does not purge a "?p="
+ * address either, nothing to probe then).
+ */
+final class SuperCacheProbe
+{
+    private const SLUG_PREFIX = 'lit-mcp-check-';
+    private const CLEAR_ON_EDIT = 'wp_cache_clear_on_post_edit';
+    private const RELATED_PAGES_FILTER = 'wpsc_delete_related_pages_on_edit';
+    /** Files WPSC writes per page and protocol, and what a purge renames them to. */
+    private const CACHE_FILES = ['index.html', 'index-https.html'];
+    private const REBUILD_SUFFIX = '.needs-rebuild';
+
+    private const ABORTED = 'Super-Cache-Probe abgebrochen (Details im PHP-Error-Log).';
+    private const NOT_PURGED = 'Die Testdatei im Cache blieb nach dem Leeren durch WP Super Cache bestehen.';
+    private const NOT_PRIVATE = 'Der Status der Testseite konnte nicht gesetzt werden (Details im PHP-Error-Log).';
+    private const NOT_WRITTEN = 'Die Testdatei konnte nicht im Cache-Verzeichnis angelegt werden '
+        . '(Details im PHP-Error-Log).';
+
+    private Closure $enabled;
+    private Closure $cacheDir;
+    private Closure $purge;
+    private Closure $setStatus;
+
+    /**
+     * Defaults are the real WPSC and WordPress calls; closures only for tests.
+     *
+     * @param (Closure(): bool)|null          $enabled   WPSC caching switched on ($cache_enabled).
+     * @param (Closure(int): ?string)|null    $cacheDir  Cache directory (with trailing slash) of a page; null = none.
+     * @param (Closure(int): void)|null       $purge     wp_cache_post_edit($postId).
+     * @param (Closure(int, string): bool)|null $setStatus Sets status (and the slug) of the page without hooks;
+     *     false = the database did not change it.
+     */
+    public function __construct(
+        ?Closure $enabled = null,
+        ?Closure $cacheDir = null,
+        ?Closure $purge = null,
+        ?Closure $setStatus = null
+    ) {
+        $this->enabled = $enabled ?? static fn (): bool => ! empty($GLOBALS['cache_enabled']);
+        $this->cacheDir = $cacheDir ?? self::cacheDirFor(...);
+        $this->purge = $purge ?? self::purgeThisPageOnly(...);
+        $this->setStatus = $setStatus ?? self::writeStatus(...);
+    }
+
+    /** @return list<string>|null German problems, [] = green; null = nothing to probe (cache off, no usable path). */
+    public function run(): ?array
+    {
+        if (! ($this->enabled)()) {
+            return null;
+        }
+
+        $unchecked = false;
+        $problems = self::throwaway()->run('page', function (int $id) use (&$unchecked): array {
+            try {
+                if (! ($this->setStatus)($id, 'private')) {
+                    Log::line('wpsc probe: the database did not set page ' . $id . ' to private.');
+
+                    return [self::NOT_PRIVATE];
+                }
+                $dir = ($this->cacheDir)($id);
+                if ($dir === null) {
+                    $unchecked = true;
+
+                    return [];
+                }
+
+                return $this->exercise($id, $dir);
+            } finally {
+                $this->resetToDraft($id);
+            }
+        });
+
+        return $unchecked && $problems === [] ? null : $problems;
+    }
+
+    /** @return list<int> IDs of probe pages a dead check left behind (draft or private), deleted now. */
+    public static function removeOrphans(): array
+    {
+        return self::throwaway()->removeOrphans('page');
+    }
+
+    private static function throwaway(): ThrowawayPost
+    {
+        return new ThrowawayPost(
+            ThrowawayPost::MARKER,
+            ThrowawayPost::TITLE,
+            self::ABORTED,
+            'Die Probe-Seite konnte nicht angelegt werden (Details im PHP-Error-Log).',
+            'Die Probe-Seite %d konnte nicht gelöscht werden; bitte endgültig löschen (Titel „'
+                . ThrowawayPost::TITLE . ' …“).',
+            'wpsc probe'
+        );
+    }
+
+    /** Must not hide the result of the probe or end the check: the page is deleted right after anyway. */
+    private function resetToDraft(int $id): void
+    {
+        try {
+            if (! ($this->setStatus)($id, 'draft')) {
+                Log::line('wpsc probe: the database did not set page ' . $id . ' back to draft.');
+            }
+        } catch (Throwable $e) {
+            Log::failure('wpsc probe', $e);
+        }
+    }
+
+    /**
+     * WPSC's own cache directory of the probe page, or null when the probe must not use it: anything but exactly
+     * <home host directory>/<probe slug>/ – another host than the home URL's (WPSC takes it from the request), a
+     * plain "?p=" address or an empty slug (both resolve to the home page's directory), a path with "..".
+     */
+    public static function cacheDirFor(int $postId): ?string
+    {
+        $home = (string) get_supercache_dir();
+        $dir = (string) get_current_url_supercache_dir($postId);
+
+        return $home !== '' && $dir === $home . self::SLUG_PREFIX . $postId . '/' ? $dir : null;
+    }
+
+    /** wp_cache_post_edit for the probe page only: see the class comment. Global and filter are put back exactly. */
+    private static function purgeThisPageOnly(int $id): void
+    {
+        $hadGlobal = array_key_exists(self::CLEAR_ON_EDIT, $GLOBALS);
+        $before = $GLOBALS[self::CLEAR_ON_EDIT] ?? null;
+        // A closure of its own: remove_filter must not take away a "__return_false" another plugin added.
+        $off = static fn (): bool => false;
+        try {
+            $GLOBALS[self::CLEAR_ON_EDIT] = 0;
+            add_filter(self::RELATED_PAGES_FILTER, $off, PHP_INT_MAX);
+            wp_cache_post_edit($id);
+        } finally {
+            remove_filter(self::RELATED_PAGES_FILTER, $off, PHP_INT_MAX);
+            if ($hadGlobal) {
+                $GLOBALS[self::CLEAR_ON_EDIT] = $before;
+            } else {
+                unset($GLOBALS[self::CLEAR_ON_EDIT]);
+            }
+        }
+    }
+
+    // The probe's own file in WPSC's own cache directory, written the way WPSC does it (plain PHP, no WP_Filesystem).
+    // phpcs:disable WordPress.WP.AlternativeFunctions
+
+    /** @return list<string> */
+    private function exercise(int $id, string $dir): array
+    {
+        $file = $dir . 'index.html';
+        try {
+            if (! wp_mkdir_p($dir) || file_put_contents($file, '<!-- lit-mcp purge probe -->') === false) {
+                Log::line('wpsc probe: could not write the test file ' . $file);
+
+                return [self::NOT_WRITTEN];
+            }
+
+            ($this->purge)($id);
+            clearstatcache(true, $file);
+            if (! file_exists($file)) {
+                return [];
+            }
+
+            Log::line('wpsc probe: wp_cache_post_edit left the test file ' . $file . ' in place.');
+
+            return [self::NOT_PURGED];
+        } finally {
+            foreach (self::CACHE_FILES as $name) {
+                @unlink($dir . $name);
+                @unlink($dir . $name . self::REBUILD_SUFFIX);
+            }
+            @rmdir($dir);
+        }
+    }
+
+    // phpcs:enable WordPress.WP.AlternativeFunctions
+
+    /** Status and a fixed slug (an empty one would make the page's address the home page) – no hooks, no clean_post_cache. */
+    private static function writeStatus(int $id, string $status): bool
+    {
+        global $wpdb;
+
+        $columns = ['post_status' => $status, 'post_name' => self::SLUG_PREFIX . $id];
+        $rows = $wpdb->update($wpdb->posts, $columns, ['ID' => $id]);
+        wp_cache_delete($id, 'posts');
+
+        return $rows !== false && (int) $rows > 0;
+    }
+}

tests/Integration/lib.sh

@@ -5,6 +5,13 @@
 # sourcing – HOST below shells out to `wp` immediately).
 # Requires jq and curl (both present in the DDEV web image).
 
+# Mutual exclusion of ALL smokes (every one sources this file inside the same web container): two at once would
+# share one site state – WP Super Cache edits wp-config.php, every smoke empties the test application passwords of the
+# admin (cleanup_app_passwords_for, harmless only because of this lock), Pods/Divi release options. The lock lives as
+# long as the script (fd 9 closes with it); a smoke that runs a second one itself must not source this file twice.
+exec 9>/tmp/lit-mcp-smoke.lock
+flock -n 9 || { echo "FAIL: another smoke is running (lock /tmp/lit-mcp-smoke.lock)"; exit 1; }
+
 PLUGIN=wp-content/plugins/WP-LIT-MCP
 ENDPOINT=http://localhost/wp-json/mcp/mcp-oauth-server
 
@@ -14,6 +21,10 @@ ENDPOINT=http://localhost/wp-json/mcp/mcp-oauth-server
 # the code under test.
 HOST=$(wp option get home | sed -E 's#^[a-zA-Z]+://##')
 
+# Optional: the Host header MCP requests carry (default: curl's own, "localhost"). A cache plugin that keys its files
+# by the request's host (WP Super Cache) needs the site's real host here (super-cache-smoke.sh sets it).
+MCP_HOST=${MCP_HOST:-}
+
 TOKEN=""
 SESSION=""
 INIT_RESPONSE=""
@@ -36,7 +47,8 @@ guard_exit() {
 }
 pass() { echo "ok   - $*"; }
 
-# Removes every "lit-mcp-integration-test" application password of a user.
+# Removes every "lit-mcp-integration-test" application password of a user (of ANY run – safe only under the smoke
+# lock above: no other smoke can be using one).
 cleanup_app_passwords_for() { # $1 = user_login
   local login="$1"
   [ -n "$login" ] || return 0
@@ -68,7 +80,10 @@ mint_token() { # $1 = user_login -> prints the token
 mcp() { # $1 = token, $2 = json body, $3 = session id (optional)
   local session_header=()
   [ -n "${3:-}" ] && session_header=(-H "Mcp-Session-Id: $3")
+  local host_header=()
+  [ -n "$MCP_HOST" ] && host_header=(-H "Host: $MCP_HOST")
   curl -s --max-time 20 -i -X POST "$ENDPOINT" \
+    "${host_header[@]}" \
     -H "Authorization: Bearer $1" \
     -H 'Content-Type: application/json' \
     -H 'Accept: application/json, text/event-stream' \
@@ -93,7 +108,10 @@ rpc() { # $1 = method, $2 = params JSON
   body=$(jq -cn --arg m "$1" --argjson p "$2" --argjson id "$REQUEST_ID" '{jsonrpc: "2.0", id: $id, method: $m, params: $p}')
   local session_header=()
   [ -n "$SESSION" ] && session_header=(-H "Mcp-Session-Id: $SESSION")
+  local host_header=()
+  [ -n "$MCP_HOST" ] && host_header=(-H "Host: $MCP_HOST")
   curl -s --max-time 60 -X POST "$ENDPOINT" \
+    "${host_header[@]}" \
     -H "Authorization: Bearer $TOKEN" \
     -H 'Content-Type: application/json' \
     -H 'Accept: application/json, text/event-stream' \

tests/Integration/pods-compat-smoke.sh

@@ -89,9 +89,9 @@ pass "tab Compatibility: Pods section with version and state, check button, no r
 # an unmarked entry with the same title are not.
 ORPHANS=$(wp --user="$ADMIN_LOGIN" eval '
 $make = static fn (string $date, bool $marked): int => (int) wp_insert_post([
-    "post_type" => "lit_person", "post_status" => "draft", "post_title" => LIT\MCP\Integrations\Pods\PodsProbe::TITLE . " smoke",
+    "post_type" => "lit_person", "post_status" => "draft", "post_title" => LIT\MCP\Compatibility\ThrowawayPost::TITLE . " smoke",
     "post_date" => get_date_from_gmt($date), "post_date_gmt" => $date,
-    "meta_input" => $marked ? [LIT\MCP\Integrations\Pods\PodsProbe::MARKER => "1"] : [],
+    "meta_input" => $marked ? [LIT\MCP\Compatibility\ThrowawayPost::MARKER => "1"] : [],
 ]);
 $old = $make(gmdate("Y-m-d H:i:s", time() - 3600), true);
 $young = $make(gmdate("Y-m-d H:i:s"), true);

tests/Integration/super-cache-smoke.sh

@@ -0,0 +1,303 @@
+#!/usr/bin/env bash
+# End-to-end checks of the WP Super Cache profile of the compatibility layer (plan 2026-11-06-kompatibilitaetsschicht,
+# 2.5 and 2.6): status, check route /wpsc-check with the purge probe (cache off and on), the purge after a write of
+# this plugin without wp_update_post (terms), the whole-cache purge after a setting, its throttle and the trailing
+# purge by cron. Runs INSIDE the DDEV web container:
+#   cd /home/janniclas/Projekte/WordPress && timeout 600 ddev exec bash wp-content/plugins/WP-LIT-MCP/tests/Integration/super-cache-smoke.sh
+#
+# SIDE EFFECTS, all undone by the EXIT trap and proven at the end (verify_restored): activating WP Super Cache edits
+# wp-config.php (WP_CACHE, WPCACHEHOME), creates wp-content/advanced-cache.php and wp-content/wp-cache-config.php,
+# fills wp-content/cache/ and schedules wp_cache_* cron events and options. The script saves wp-config.php (and the
+# files named in SAVED_FILES, if they exist) first, deactivates the plugin and writes the saved state back, byte for byte (sha256).
+# It uses the plain PHP cache mode ($wp_cache_mod_rewrite = 0): no .htaccess rewrite rules are ever written; the run
+# refuses to start if the cache directory is not empty, WP Super Cache is already active or WP_CACHE is already set.
+set -euo pipefail
+cd /var/www/html
+# shellcheck source=lib.sh
+source wp-content/plugins/WP-LIT-MCP/tests/Integration/lib.sh
+
+ROOT=/var/www/html
+CACHE_DIR=$ROOT/wp-content/cache
+SUPERCACHE_DIR=$CACHE_DIR/supercache
+WP_CONFIG=$ROOT/wp-config.php
+HTACCESS=$ROOT/.htaccess
+SAVED_FILES=(wp-content/advanced-cache.php wp-content/wp-cache-config.php .htaccess)
+CRON_PATTERN='wp_cache|wpsc|lit_mcp_wpsc'
+OPTION_PATTERN='wpsc|wp_super_cache|wp_cache|super_cache|lit_mcp_wpsc'
+TRAILING_HOOK=lit_mcp_wpsc_trailing_purge
+PURGED_AT=lit_mcp_wpsc_purged_at
+BASE=http://localhost
+
+ADMIN_LOGIN=$(wp user list --role=administrator --field=user_login | head -1)
+PREFIX=$(wp db prefix)
+
+# --- Guards: nothing is changed before all of them pass ------------------------------------------------------------
+wp plugin is-active wp-super-cache 2>/dev/null && fail "WP Super Cache is already active; this smoke expects it inactive"
+grep -Eq "^\s*(define\s*\(\s*['\"]WP_CACHE['\"]|const\s+WP_CACHE\s*=)" "$WP_CONFIG" && fail "wp-config.php already sets WP_CACHE"
+[ -d "$CACHE_DIR" ] && [ -n "$(find "$CACHE_DIR" -mindepth 1 -print -quit)" ] && fail "$CACHE_DIR is not empty; refusing to touch a cache"
+
+# --- Snapshot of everything the run can change ---------------------------------------------------------------------
+BACKUP=$(mktemp -d)
+sums() { sha256sum "$@" 2>/dev/null | awk '{print $1}'; }
+CONFIG_SUM_BEFORE=$(sums "$WP_CONFIG")
+CONFIG_STAT_BEFORE=$(stat -c '%a %U:%G' "$WP_CONFIG")
+# cp -a, not -p: wp-config.php carries an ACL entry; WP Super Cache replaces the file (new inode) and loses it, and
+# only cp -a writes it back with the content.
+cp -a "$WP_CONFIG" "$BACKUP/wp-config.php"
+[ "$(sums "$BACKUP/wp-config.php")" = "$CONFIG_SUM_BEFORE" ] || fail "could not save wp-config.php"
+for f in "${SAVED_FILES[@]}"; do
+  if [ -e "$ROOT/$f" ]; then cp -a "$ROOT/$f" "$BACKUP/$(basename "$f")"; echo "$(sums "$ROOT/$f")" > "$BACKUP/$(basename "$f").sum"; fi
+done
+HTACCESS_BEFORE=absent; [ -e "$HTACCESS" ] && HTACCESS_BEFORE=$(sums "$HTACCESS")
+CACHE_DIR_EXISTED=no; CACHE_DIR_MODE=775
+if [ -d "$CACHE_DIR" ]; then CACHE_DIR_EXISTED=yes; CACHE_DIR_MODE=$(stat -c '%a' "$CACHE_DIR"); fi
+list_hooks() { wp cron event list --fields=hook --format=csv | tail -n +2 | grep -E "$CRON_PATTERN" | sort -u || true; }
+list_options() { wp db query "SELECT option_name FROM ${PREFIX}options WHERE option_name REGEXP '$OPTION_PATTERN' ORDER BY option_name" --skip-column-names; }
+HOOKS_BEFORE=$(list_hooks)
+OPTIONS_BEFORE=$(list_options)
+ACTIVE_PLUGINS_BEFORE=$(wp option get active_plugins --format=json)
+ORIGINAL_DESCRIPTION=$(wp option get blogdescription)
+CREATED_POSTS=()
+CREATED_TERMS=()
+
+# --- Restore ---------------------------------------------------------------------------------------------------------
+# A saved file is written back atomically: a copy next to the target (same file system), then mv – a run killed in
+# the middle never leaves a half-written wp-config.php.
+restore_file() { # $1 = path relative to ROOT
+  local name tmp; name=$(basename "$1")
+  if [ -e "$BACKUP/$name" ]; then
+    tmp=$(mktemp "$ROOT/$(dirname "$1")/.$name.restore.XXXXXX") \
+      && cp -a "$BACKUP/$name" "$tmp" && mv -f "$tmp" "$ROOT/$1" || { rm -f "$tmp"; return 1; }
+  else
+    rm -f "$ROOT/$1"
+  fi
+}
+
+restore() {
+  set +e
+  local id term hook option
+  for id in "${CREATED_POSTS[@]}"; do wp post delete "$id" --force >/dev/null 2>&1; done
+  for term in "${CREATED_TERMS[@]}"; do wp term delete category "$term" >/dev/null 2>&1; done
+  wp option update blogdescription "$ORIGINAL_DESCRIPTION" >/dev/null 2>&1
+  wp option delete lit_mcp_wpsc_check_report lit_mcp_wpsc_releases lit_mcp_wpsc_check_lock >/dev/null 2>&1
+  wp transient delete "$PURGED_AT" >/dev/null 2>&1
+  cleanup_app_passwords_for "$ADMIN_LOGIN"
+  # Deactivation lets WP Super Cache undo its own edits (WP_CACHE, WPCACHEHOME, advanced-cache.php, cache files) ...
+  wp plugin is-active wp-super-cache >/dev/null 2>&1 && wp plugin deactivate wp-super-cache >/dev/null 2>&1
+  # ... and what it leaves, or does differently, is set back from the saved state.
+  restore_file wp-config.php
+  for id in "${SAVED_FILES[@]}"; do restore_file "$id"; done
+  [ -d "$CACHE_DIR" ] && find "$CACHE_DIR" -mindepth 1 -delete
+  if [ "$CACHE_DIR_EXISTED" = no ]; then
+    rmdir "$CACHE_DIR" 2>/dev/null
+  else
+    # Deactivation removes the whole cache directory; mkdir -m keeps the inherited ACL of its parent.
+    [ -d "$CACHE_DIR" ] || mkdir -m "$CACHE_DIR_MODE" "$CACHE_DIR"
+  fi
+  # The profile's cron event and every option or event the plugin added.
+  for hook in $(list_hooks); do
+    grep -qx "$hook" <<<"$HOOKS_BEFORE" || wp cron event delete "$hook" >/dev/null 2>&1
+  done
+  for option in $(list_options); do
+    grep -qx "$option" <<<"$OPTIONS_BEFORE" || wp option delete "$option" >/dev/null 2>&1
+  done
+  set -e
+}
+
+# Prints the proof; returns non-zero on any difference (used in the trap, so it must not exit).
+verify_restored() {
+  local ok=0 name after
+  after=$(sums "$WP_CONFIG")
+  if [ "$after" = "$CONFIG_SUM_BEFORE" ]; then pass "restored: wp-config.php sha256 $CONFIG_SUM_BEFORE (before) == $after (after)"
+  else echo "FAIL: wp-config.php sha256 $CONFIG_SUM_BEFORE (before) != $after (after)"; ok=1; fi
+  [ "$(stat -c '%a %U:%G' "$WP_CONFIG")" = "$CONFIG_STAT_BEFORE" ] \
+    || { echo "FAIL: wp-config.php mode/owner changed: $CONFIG_STAT_BEFORE -> $(stat -c '%a %U:%G' "$WP_CONFIG")"; ok=1; }
+  for f in "${SAVED_FILES[@]}"; do
+    name=$(basename "$f")
+    if [ -e "$BACKUP/$name" ]; then
+      [ "$(sums "$ROOT/$f")" = "$(cat "$BACKUP/$name.sum")" ] || { echo "FAIL: $f differs from the saved one"; ok=1; }
+    else
+      [ ! -e "$ROOT/$f" ] || { echo "FAIL: $f was absent before and exists now"; ok=1; }
+    fi
+  done
+  [ "$ok" = 0 ] && pass "restored: advanced-cache.php and wp-cache-config.php as before (absent: $([ -e "$BACKUP/advanced-cache.php" ] && echo no || echo yes))"
+  local htaccess_after=absent; [ -e "$HTACCESS" ] && htaccess_after=$(sums "$HTACCESS")
+  [ "$htaccess_after" = "$HTACCESS_BEFORE" ] || { echo "FAIL: .htaccess changed ($HTACCESS_BEFORE -> $htaccess_after)"; ok=1; }
+  if [ "$CACHE_DIR_EXISTED" = yes ]; then
+    [ -d "$CACHE_DIR" ] && [ -z "$(find "$CACHE_DIR" -mindepth 1 -print -quit)" ] && [ "$(stat -c '%a' "$CACHE_DIR")" = "$CACHE_DIR_MODE" ] \
+      || { echo "FAIL: cache directory not empty, gone or its mode changed"; ok=1; }
+  else
+    [ ! -e "$CACHE_DIR" ] || { echo "FAIL: cache directory was absent before and exists now"; ok=1; }
+  fi
+  wp plugin is-active wp-super-cache 2>/dev/null && { echo "FAIL: WP Super Cache is still active"; ok=1; }
+  [ "$(wp option get active_plugins --format=json)" = "$ACTIVE_PLUGINS_BEFORE" ] || { echo "FAIL: active_plugins differs"; ok=1; }
+  [ "$(list_hooks)" = "$HOOKS_BEFORE" ] || { echo "FAIL: cron events differ: $(list_hooks | tr '\n' ' ')"; ok=1; }
+  [ "$(list_options)" = "$OPTIONS_BEFORE" ] || { echo "FAIL: options differ: $(list_options | tr '\n' ' ')"; ok=1; }
+  [ -z "$(wp transient get "$PURGED_AT" 2>/dev/null || true)" ] || { echo "FAIL: transient $PURGED_AT left"; ok=1; }
+  [ "$(wp option get blogdescription)" = "$ORIGINAL_DESCRIPTION" ] || { echo "FAIL: blogdescription not restored"; ok=1; }
+  [ "$(wp post list --post_type=any --post_status=any --meta_key=_lit_mcp_check_entry --format=count)" = 0 ] \
+    || { echo "FAIL: a probe page is left"; ok=1; }
+  [ "$(wp post list --post_type=post --post_status=any --name=lit-wpsc-smoke --format=count)" = 0 ] \
+    || { echo "FAIL: the test post is left"; ok=1; }
+  return "$ok"
+}
+
+on_exit() {
+  local rc=$1
+  restore
+  verify_restored || rc=1
+  rm -rf "$BACKUP"
+  guard_exit "$rc" || exit $?
+  exit "$rc"
+}
+trap 'on_exit $?' EXIT
+trap 'exit 130' INT TERM HUP
+
+# --- Helpers ---------------------------------------------------------------------------------------------------------
+wpsc_component() { tool lit-site-status '{}' | jq -c '.components[] | select(.id == "wpsc")'; }
+stored_option() { wp option get "$1" --format=json 2>/dev/null || true; }
+event_count() { wp cron event list --hook="$TRAILING_HOOK" --format=count 2>/dev/null || echo 0; }
+# The cache file of the test post as WP Super Cache keeps it (index.html; a ".needs-rebuild" copy is a purged one).
+cache_file() { find "$SUPERCACHE_DIR" -type f -path '*lit-wpsc-smoke*' -name index.html 2>/dev/null | head -1; }
+wait_for() { # $1 = description, rest = command; polls up to 15 s
+  local what=$1 i; shift
+  for i in $(seq 1 15); do "$@" && return 0; sleep 1; done
+  fail "timeout: $what"
+}
+cache_file_exists() { [ -n "$(cache_file)" ]; }
+cache_file_gone() { [ -z "$(cache_file)" ]; }
+front_page_by_wpsc() { [[ "$(curl -s -H "Host: $HOST" "$BASE/")" == *WP-Super-Cache* ]]; }
+# One public request for the test post; the cache file appears at the end of the request.
+fetch_post() {
+  local code
+  code=$(curl -s -o /dev/null -w '%{http_code}' -H "Host: $HOST" "$BASE$POST_PATH")
+  [ "$code" = 200 ] || fail "GET $POST_PATH answered $code"
+}
+# Requests the test post until WP Super Cache has written its file (the first request after a purge or a new post
+# is not always the one that is stored).
+fill_cache() {
+  local i
+  for i in $(seq 1 10); do
+    fetch_post
+    sleep 1
+    cache_file_exists && return 0
+  done
+  echo "--- response of $POST_PATH (selected headers) and the cache tree:"
+  curl -s -i -H "Host: $HOST" "$BASE$POST_PATH" | grep -iE '^(HTTP|cache-control|set-cookie)|WP Super Cache|Page not cached' | head -10
+  find "$CACHE_DIR" | head -20
+  fail "timeout: cache file of the test post"
+}
+config_value() { grep -E "^\s*\\\$$1\s*=" "$ROOT/wp-content/wp-cache-config.php" | head -1; }
+
+# --- 0. Activate and look at what WP Super Cache did ------------------------------------------------------------------
+wp plugin activate wp-super-cache >/dev/null 2>&1 || fail "could not activate WP Super Cache"
+grep -q "define( *'WP_CACHE', *true *)" "$WP_CONFIG" || fail "activation did not set WP_CACHE (the run cannot cache)"
+[ -e "$ROOT/wp-content/advanced-cache.php" ] || fail "activation did not create advanced-cache.php"
+# WP Super Cache keys its files by the host of the request: MCP calls must carry the host the page was cached under.
+MCP_HOST=$HOST
+connect "$ADMIN_LOGIN"
+
+# 1. Status
+wpsc_component | jq -e '.active == true and .version == "3.1.5" and .problems == []' >/dev/null \
+  || fail "site status must show WP Super Cache 3.1.5 active without problems: $(wpsc_component)"
+pass "lit-site-status: WP Super Cache 3.1.5 active, no problems"
+
+# 2. Check route with the cache still switched off: the probe step is green and says "not checked"
+APP_PASSWORD=$(wp user application-password create "$ADMIN_LOGIN" lit-mcp-integration-test --porcelain)
+run_check() {
+  local headers
+  headers=$(curl -s -o /dev/null -D - -X POST -H "Host: $HOST" -H 'X-Forwarded-Proto: https' -u "$ADMIN_LOGIN:$APP_PASSWORD" "$BASE/wp-json/lit-mcp/v1/wpsc-check")
+  echo "$headers" | grep -qi '^HTTP/[0-9.]* 303' || fail "check route must answer 303: $headers"
+  echo "$headers" | grep -qi '^location:.*tab=compatibility.*lit_mcp_notice=compat_checked' || fail "redirect to the tab: $headers"
+}
+[ "$(wp eval 'echo (int) ! empty($GLOBALS["cache_enabled"]);')" = 0 ] || fail "the cache must be off after activation"
+run_check
+REPORT=$(stored_option lit_mcp_wpsc_check_report)
+echo "$REPORT" | jq -e '(.steps | length) == 2 and all(.steps[]; .problems == [] and .skipped == false)
+  and ([.steps[] | select(.key == "probe")] | length == 1 and (.[0].label | contains("Cache ist ausgeschaltet, nicht geprüft")))' >/dev/null \
+  || fail "cache off: the report must be green and the probe must say it did not check: $REPORT"
+pass "/wpsc-check with the cache off: green, probe step says 'Cache ist ausgeschaltet, nicht geprüft'"
+
+# 3. Switch the cache on in the plain PHP mode (no mod_rewrite, no .htaccess)
+wp eval 'wp_cache_enable();' >/dev/null 2>&1 || fail "wp_cache_enable failed"
+# PHP-FPM's opcache re-reads a changed wp-cache-config.php at most every 2 s: wait until a public request is served
+# by WP Super Cache (its HTML comment), the state the checks below need.
+wait_for "WP Super Cache serves public requests" front_page_by_wpsc
+config_value cache_enabled | grep -q 'true' || fail "wp-cache-config.php: cache_enabled is not true: $(config_value cache_enabled)"
+config_value wp_cache_mod_rewrite | grep -Eq '= *0;' || fail "mod_rewrite mode is on: $(config_value wp_cache_mod_rewrite)"
+config_value super_cache_enabled | grep -q 'true' || fail "super_cache_enabled is not true: $(config_value super_cache_enabled)"
+[ "$(config_value wp_cache_clear_on_post_edit | grep -Ec '= *0;')" = 1 ] || fail "clear_on_post_edit must be 0: $(config_value wp_cache_clear_on_post_edit)"
+[ ! -e "$HTACCESS" ] || [ "$(sums "$HTACCESS")" = "$HTACCESS_BEFORE" ] || fail ".htaccess changed"
+pass "cache on in the plain PHP mode (mod_rewrite 0, clear_on_post_edit 0), .htaccess untouched"
+
+# 4. Check route with the cache on: the purge probe really runs
+run_check
+REPORT=$(stored_option lit_mcp_wpsc_check_report)
+echo "$REPORT" | jq -e '(.steps | length) == 2 and all(.steps[]; .problems == [] and .skipped == false)
+  and ([.steps[] | select(.key == "probe")] | length == 1 and (.[0].label | contains("nicht geprüft") | not))
+  and .version == "3.1.5"' >/dev/null || fail "cache on: the report must be green with a real probe step: $REPORT"
+[ -z "$(stored_option lit_mcp_wpsc_check_lock)" ] || fail "the check lock must be released"
+[ "$(wp post list --post_type=any --post_status=any --meta_key=_lit_mcp_check_entry --format=count)" = 0 ] || fail "the probe left a page behind"
+[ "$(find "$SUPERCACHE_DIR" -path '*lit-mcp-check-*' -print -quit 2>/dev/null)" = "" ] || fail "the probe left a cache directory behind"
+UNAUTH=$(curl -s -o /dev/null -w '%{http_code}' -X POST -H "Host: $HOST" -H 'X-Forwarded-Proto: https' "$BASE/wp-json/lit-mcp/v1/wpsc-check")
+[ "$UNAUTH" = 401 ] || [ "$UNAUTH" = 403 ] || fail "anonymous check must be refused, got $UNAUTH"
+pass "/wpsc-check with the cache on: green with the purge probe, no page or cache directory left, anonymous refused"
+
+# 5. A published test post, fetched until it is in the cache
+CAT_A=$(wp term create category "LIT WPSC Smoke A" --porcelain); CREATED_TERMS+=("$CAT_A")
+CAT_B=$(wp term create category "LIT WPSC Smoke B" --porcelain); CREATED_TERMS+=("$CAT_B")
+POST_ID=$(wp post create --post_type=post --post_status=publish --post_title="LIT WPSC Smoke" --post_name=lit-wpsc-smoke \
+  --post_content="Testbeitrag fuer den Super-Cache-Smoke." --porcelain)
+CREATED_POSTS+=("$POST_ID")
+POST_PATH=$(wp eval "echo wp_parse_url(get_permalink($POST_ID), PHP_URL_PATH);")
+fill_cache
+pass "test post $POST_ID cached: $(cache_file | sed "s#$CACHE_DIR/##")"
+
+# 6. Control: a term change outside this plugin does not touch the cache (WP Super Cache never sees it) ...
+wp post term set "$POST_ID" category "$CAT_A" >/dev/null
+sleep 2
+cache_file_exists || fail "control: WP Super Cache itself purged on a plain term change; the next check proves nothing"
+# ... but the same kind of change through lit-content-update (no wp_update_post) empties the cache of the post.
+REV=$(tool lit-content-get "{\"post_id\":$POST_ID}" | jq -r '.rev')
+UPDATED=$(tool lit-content-update "{\"post_id\":$POST_ID,\"rev\":\"$REV\",\"terms\":{\"category\":[$CAT_B]}}")
+echo "$UPDATED" | jq -e '.ok == true' >/dev/null || fail "lit-content-update (terms only): $UPDATED"
+wait_for "the cache file of the post is gone after lit-content-update" cache_file_gone
+[ "$(event_count)" = 0 ] || fail "a single-post purge must not schedule a trailing purge"
+pass "terms-only lit-content-update empties the cache of the post (a plain term change does not), no trailing event"
+
+# 7. Whole-cache purge after a setting; the second one inside 30 s is throttled and leaves exactly one cron event
+fill_cache
+[ -z "$(wp transient get "$PURGED_AT" 2>/dev/null || true)" ] || fail "transient $PURGED_AT set before the first whole purge"
+ability lit/wp-settings-update '{"settings":{"blogdescription":"LIT WPSC Smoke 1"}}' | jq -e '.ok == true' >/dev/null || fail "settings update 1"
+wait_for "the cache is empty after a setting change" cache_file_gone
+wait_for "the purge time is stored" bash -c "[ -n \"\$(wp transient get $PURGED_AT 2>/dev/null)\" ]"
+LAST=$(wp transient get "$PURGED_AT")
+[ "$(event_count)" = 0 ] || fail "the first whole purge must not schedule a trailing purge"
+pass "setting change empties the whole cache (purge time stored, no trailing event)"
+
+fill_cache
+ability lit/wp-settings-update '{"settings":{"blogdescription":"LIT WPSC Smoke 2"}}' | jq -e '.ok == true' >/dev/null || fail "settings update 2"
+wait_for "one trailing purge is scheduled" bash -c "[ \"\$(wp cron event list --hook=$TRAILING_HOOK --format=count)\" = 1 ]"
+sleep 2
+cache_file_exists || fail "throttled: the second whole purge ran inside the lock time"
+ability lit/wp-settings-update '{"settings":{"blogdescription":"LIT WPSC Smoke 3"}}' | jq -e '.ok == true' >/dev/null || fail "settings update 3"
+sleep 3
+[ "$(event_count)" = 1 ] || fail "exactly one trailing event must stay scheduled, found $(event_count)"
+cache_file_exists || fail "throttled: the third whole purge ran inside the lock time"
+[ "$(wp transient get "$PURGED_AT")" = "$LAST" ] || fail "throttled purges must not move the purge time"
+pass "second and third whole purge inside 30 s: throttled (file stays, purge time unchanged), exactly one $TRAILING_HOOK event"
+
+# 8. Run the trailing purge once the lock is over: the cache is emptied and nothing is scheduled any more
+WAIT=$((LAST + 32 - $(date +%s))); [ "$WAIT" -gt 0 ] && sleep "$WAIT"
+wp cron event run "$TRAILING_HOOK" >/dev/null 2>&1 || fail "wp cron event run $TRAILING_HOOK"
+cache_file_gone || fail "the trailing purge did not empty the cache"
+[ "$(event_count)" = 0 ] || fail "no trailing event may be left after it ran"
+[ "$(wp transient get "$PURGED_AT")" -gt "$LAST" ] || fail "the trailing purge must store a new purge time"
+pass "trailing purge by cron: cache emptied, event gone, purge time renewed"
+
+# 9. Everything back as before (the EXIT trap would do it too; here it is part of the verdict)
+restore
+verify_restored || fail "the state before the run was not restored"
+pass "cleanup: plugin inactive, test post, categories, options, transient and cron events gone"
+
+finish

tests/Unit/Compatibility/ProbeStepTest.php

@@ -0,0 +1,80 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Compatibility;
+
+use Closure;
+use LIT\MCP\Compatibility\ProbeStep;
+use LIT\MCP\Tests\Unit\TestCase;
+use RuntimeException;
+
+final class ProbeStepTest extends TestCase
+{
+    /** @param Closure(): (list<string>|null) $probe */
+    private function step(Closure $probe): Closure
+    {
+        return ProbeStep::extra('probe', 'Prüfung', 'Prüfung (nichts zu prüfen)', $probe);
+    }
+
+    public function testASkippedStepWithARedManifestThatNeverRunsTheProbe(): void
+    {
+        $ran = false;
+        $steps = $this->step(static function () use (&$ran): array {
+            $ran = true;
+
+            return [];
+        })(false);
+
+        self::assertCount(1, $steps);
+        self::assertSame('probe', $steps[0]->key);
+        self::assertTrue($steps[0]->skipped);
+        self::assertFalse($steps[0]->green());
+        self::assertSame('Prüfung', $steps[0]->label());
+        self::assertFalse($ran);
+    }
+
+    /** Nothing to probe is no red step: a skipped or red one would lock the plugin on a site that has nothing yet. */
+    public function testNullIsAGreenStepWithTheHintLabel(): void
+    {
+        $steps = $this->step(static fn (): ?array => null)(true);
+
+        self::assertCount(1, $steps);
+        self::assertTrue($steps[0]->green());
+        self::assertSame('Prüfung (nichts zu prüfen)', $steps[0]->label());
+    }
+
+    public function testGreenKeepsTheNormalLabel(): void
+    {
+        $steps = $this->step(static fn (): array => [])(true);
+
+        self::assertTrue($steps[0]->green());
+        self::assertSame('Prüfung', $steps[0]->label());
+    }
+
+    public function testProblemsArePassedThrough(): void
+    {
+        $steps = $this->step(static fn (): array => ['rot', 'gelb'])(true);
+
+        self::assertSame(['rot', 'gelb'], $steps[0]->problems);
+        self::assertFalse($steps[0]->skipped);
+        self::assertSame('Prüfung', $steps[0]->label());
+    }
+
+    public function testAThrowingProbeIsOneFixedProblem(): void
+    {
+        $log = (string) tempnam(sys_get_temp_dir(), 'lit-mcp-log');
+        $previous = ini_set('error_log', $log);
+        try {
+            $steps = $this->step(static function (): never {
+                throw new RuntimeException('innen');
+            })(true);
+        } finally {
+            ini_set('error_log', (string) $previous);
+            unlink($log);
+        }
+
+        self::assertSame(['Prüfschritt abgebrochen (Details im PHP-Error-Log).'], $steps[0]->problems);
+        self::assertSame('Prüfung', $steps[0]->label());
+    }
+}

tests/Unit/Compatibility/ThrowawayPostTest.php

@@ -222,7 +222,7 @@ final class ThrowawayPostTest extends TestCase
 
         $this->throwaway()->removeOrphans(['post', 'lit_person']);
         self::assertSame(['post', 'lit_person'], $query['post_type']);
-        self::assertSame('draft', $query['post_status']);
+        self::assertSame(['draft', 'private'], $query['post_status']);
         self::assertSame('_marker', $query['meta_key']);
 
         $this->throwaway()->removeOrphans('page');
@@ -244,4 +244,20 @@ final class ThrowawayPostTest extends TestCase
 
         self::assertSame([], $this->throwaway()->removeOrphans('page'));
     }
+
+    /** A probe killed while its page was private (WP Super Cache) leaves a private page, not a draft. */
+    public function testShortStatusListCoversAProbeKilledWhilePrivate(): void
+    {
+        $query = null;
+        $this->fakeQuery([self::draft(5, 900)], $query);
+
+        self::assertSame([5], $this->throwaway()->removeOrphans('page'));
+        self::assertContains('private', $query['post_status']);
+    }
+
+    public function testTheSharedMarkerAndTitlePrefixOfTheProbes(): void
+    {
+        self::assertSame('_lit_mcp_check_entry', ThrowawayPost::MARKER);
+        self::assertSame('[LIT MCP Prüfung]', ThrowawayPost::TITLE);
+    }
 }

tests/Unit/Integrations/Divi/Release/WriteProbeTest.php

@@ -161,7 +161,7 @@ final class WriteProbeTest extends TestCase
         Functions\expect('get_posts')->once()->with(Mockery::on(static fn (array $query): bool =>
             $query['meta_key'] === '_lit_mcp_check_page'
             && $query['post_type'] === 'page'
-            && $query['post_status'] === 'draft'
+            && $query['post_status'] === ['draft', 'private']
             && ($query['date_query'][0]['column'] ?? null) === 'post_modified_gmt'))->andReturn([
                 new WP_Post(['ID' => 51, 'post_title' => WriteProbe::TITLE . ' 2026-01-01 00:00']),
                 new WP_Post(['ID' => 60, 'post_title' => 'Ein anderer Entwurf']),

tests/Unit/Integrations/Pods/PodsProbeTest.php

@@ -6,6 +6,7 @@ namespace LIT\MCP\Tests\Unit\Integrations\Pods;
 
 use Brain\Monkey\Functions;
 use Closure;
+use LIT\MCP\Compatibility\ThrowawayPost;
 use LIT\MCP\Integrations\Pods\PodsFieldSource;
 use LIT\MCP\Integrations\Pods\PodsProbe;
 use LIT\MCP\Tests\Unit\TestCase;
@@ -144,7 +145,7 @@ final class PodsProbeTest extends TestCase
 
         self::assertSame('lit_person', $this->inserted['post_type']);
         self::assertSame('draft', $this->inserted['post_status']);
-        self::assertStringStartsWith(PodsProbe::TITLE, $this->inserted['post_title']);
+        self::assertStringStartsWith(ThrowawayPost::TITLE, $this->inserted['post_title']);
         self::assertSame(['_lit_mcp_check_entry' => '1'], $this->inserted['meta_input']);
     }
 
@@ -249,7 +250,7 @@ final class PodsProbeTest extends TestCase
             $query = $args;
 
             return [
-                new WP_Post(['ID' => 5, 'post_title' => PodsProbe::TITLE . ' 2026-11-06 10:00']),
+                new WP_Post(['ID' => 5, 'post_title' => ThrowawayPost::TITLE . ' 2026-11-06 10:00']),
                 new WP_Post(['ID' => 6, 'post_title' => 'Echte Person']),
             ];
         });

tests/Unit/Integrations/SuperCache/SuperCacheCheckStepsTest.php

@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Integrations\SuperCache;
+
+use LIT\MCP\Compatibility\CheckStep;
+use LIT\MCP\Integrations\SuperCache\SuperCacheCheckSteps;
+use LIT\MCP\Integrations\SuperCache\SuperCacheCompatibility;
+use LIT\MCP\Tests\Unit\TestCase;
+
+final class SuperCacheCheckStepsTest extends TestCase
+{
+    public function testTheProbeIsSkippedWithARedManifestAndNotRun(): void
+    {
+        $ran = false;
+        $steps = SuperCacheCheckSteps::extra(static function () use (&$ran): array {
+            $ran = true;
+
+            return [];
+        })(false);
+
+        self::assertCount(1, $steps);
+        self::assertSame(SuperCacheCheckSteps::PROBE, $steps[0]->key);
+        self::assertTrue($steps[0]->skipped);
+        self::assertFalse($ran);
+    }
+
+    public function testTheStepCarriesTheProbeProblems(): void
+    {
+        $steps = SuperCacheCheckSteps::extra(static fn (): array => ['rot'])(true);
+
+        self::assertSame(['rot'], $steps[0]->problems);
+        self::assertFalse($steps[0]->skipped);
+        self::assertSame('Leeren-Test an einer Wegwerf-Seite im Cache', $steps[0]->label());
+    }
+
+    /** A switched-off cache is no red step: a skipped one would lock the purge of a site that simply caches nothing. */
+    public function testWithoutAnActiveCacheTheStepIsGreenAndSaysSo(): void
+    {
+        $steps = SuperCacheCheckSteps::extra(static fn (): ?array => null)(true);
+
+        self::assertTrue($steps[0]->green());
+        self::assertStringContainsString('Cache ist ausgeschaltet, nicht geprüft', $steps[0]->label());
+    }
+
+    public function testTheLabelOfAnOldStepComesFromTheKey(): void
+    {
+        self::assertSame('Leeren-Test an einer Wegwerf-Seite im Cache', SuperCacheCheckSteps::label(new CheckStep(SuperCacheCheckSteps::PROBE, [])));
+        self::assertSame(
+            SuperCacheCompatibility::LABEL . '-Funktionen, Klassen und Registrierungen',
+            SuperCacheCheckSteps::label(new CheckStep(CheckStep::MANIFEST, []))
+        );
+        self::assertSame('other', SuperCacheCheckSteps::label(new CheckStep('other', [])));
+    }
+}

tests/Unit/Integrations/SuperCache/SuperCacheCompatibilityTest.php

@@ -6,10 +6,12 @@ namespace LIT\MCP\Tests\Unit\Integrations\SuperCache;
 
 use Brain\Monkey\Functions;
 use LIT\MCP\Compatibility\Call;
+use LIT\MCP\Compatibility\CheckStep;
 use LIT\MCP\Compatibility\Compatibility;
 use LIT\MCP\Compatibility\Tier;
 use LIT\MCP\Integrations\Divi\Release\DiviProfile;
 use LIT\MCP\Integrations\Pods\PodsCompatibility;
+use LIT\MCP\Integrations\SuperCache\SuperCacheCheckSteps;
 use LIT\MCP\Integrations\SuperCache\SuperCacheCompatibility;
 use LIT\MCP\Integrations\SuperCache\SuperCacheFeature;
 use LIT\MCP\Tests\Unit\TestCase;
@@ -92,6 +94,21 @@ final class SuperCacheCompatibilityTest extends TestCase
         self::assertNull((SuperCacheCompatibility::profile()->version)());
     }
 
+    public function testTheCheckHasTheProbeAsExtraStep(): void
+    {
+        $profile = SuperCacheCompatibility::profile();
+
+        self::assertNotNull($profile->extraSteps);
+        $steps = ($profile->extraSteps)(false);
+        self::assertSame([SuperCacheCheckSteps::PROBE], array_map(static fn ($step): string => $step->key, $steps));
+        self::assertTrue($steps[0]->skipped);
+        self::assertNotNull($profile->stepLabel);
+        self::assertSame(
+            'Leeren-Test an einer Wegwerf-Seite im Cache',
+            ($profile->stepLabel)(new CheckStep(SuperCacheCheckSteps::PROBE, []))
+        );
+    }
+
     public function testAllProfilesCoexistWithoutIdCollision(): void
     {
         $compatibility = new Compatibility(

tests/Unit/Integrations/SuperCache/SuperCacheIntegrationTest.php

@@ -4,7 +4,10 @@ declare(strict_types=1);
 
 namespace LIT\MCP\Tests\Unit\Integrations\SuperCache;
 
+use Brain\Monkey\Functions;
+use LIT\MCP\Admin\CompatibilityTab;
 use LIT\MCP\Compatibility\ProvidesCompatibility;
+use LIT\MCP\Integrations\Bootable;
 use LIT\MCP\Integrations\Integration;
 use LIT\MCP\Integrations\SuperCache\SuperCacheCompatibility;
 use LIT\MCP\Integrations\SuperCache\SuperCacheIntegration;
@@ -28,4 +31,38 @@ final class SuperCacheIntegrationTest extends TestCase
     {
         self::assertSame(defined('WPCACHEHOME'), (new SuperCacheIntegration())->isAvailable());
     }
+
+    public function testBootHooksTheOrphanCleanupIntoTheProfileLoad(): void
+    {
+        $integration = new SuperCacheIntegration();
+        $integration->boot();
+
+        self::assertInstanceOf(Bootable::class, $integration);
+        self::assertNotFalse(has_action(CompatibilityTab::LOAD_ACTION, [$integration, 'removeOrphans']));
+    }
+
+    public function testNoCleanupForAnotherProfileWithoutWpscOrWithoutTheCapability(): void
+    {
+        Functions\expect('get_posts')->never();
+        Functions\when('current_user_can')->justReturn(true);
+        (new SuperCacheIntegration(static fn (): bool => true))->removeOrphans('pods');
+        (new SuperCacheIntegration(static fn (): bool => false))->removeOrphans('wpsc');
+
+        Functions\when('current_user_can')->justReturn(false);
+        (new SuperCacheIntegration(static fn (): bool => true))->removeOrphans('wpsc');
+        $this->addToAssertionCount(1);
+    }
+
+    public function testCleansUpPagesForTheAdministratorWithWpsc(): void
+    {
+        Functions\when('current_user_can')->justReturn(true);
+        Functions\expect('get_posts')->once()->andReturnUsing(static function (array $args): array {
+            self::assertSame('page', $args['post_type']);
+            self::assertSame(['draft', 'private'], $args['post_status']);
+
+            return [];
+        });
+
+        (new SuperCacheIntegration(static fn (): bool => true))->removeOrphans('wpsc');
+    }
 }

tests/Unit/Integrations/SuperCache/SuperCacheProbeTest.php

@@ -0,0 +1,525 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Integrations\SuperCache;
+
+use Brain\Monkey\Functions;
+use Closure;
+use LIT\MCP\Compatibility\ThrowawayPost;
+use LIT\MCP\Integrations\SuperCache\SuperCacheProbe;
+use LIT\MCP\Tests\Unit\TestCase;
+use Mockery;
+use RuntimeException;
+use WP_Post;
+
+final class SuperCacheProbeTest extends TestCase
+{
+    private string $cacheRoot = '';
+
+    /** @var list<int> */
+    private array $deleted = [];
+
+    /** @var list<string> "<id>:<status>" in call order. */
+    private array $statuses = [];
+
+    /** @var array<string, mixed>|null The wp_insert_post arguments. */
+    private ?array $inserted = null;
+
+    /** @var array<string, mixed> Globals the test changes (only those that existed). */
+    private array $savedGlobals = [];
+
+    private const GLOBALS_CHANGED = ['cache_enabled', 'cache_path', 'wpdb', 'wp_cache_clear_on_post_edit'];
+
+    /** The status the fake status switch refuses to set (returns false); null = none. */
+    private ?string $refusedStatus = null;
+
+    /** The status the fake status switch throws for; null = none. */
+    private ?string $throwingStatus = null;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->cacheRoot = sys_get_temp_dir() . '/lit-mcp-wpsc-' . bin2hex(random_bytes(4)) . '/';
+        mkdir($this->cacheRoot . 'supercache/example.test/', 0777, true);
+        $this->deleted = [];
+        $this->statuses = [];
+        $this->inserted = null;
+        $this->refusedStatus = null;
+        $this->throwingStatus = null;
+        $this->savedGlobals = [];
+        foreach (self::GLOBALS_CHANGED as $name) {
+            if (array_key_exists($name, $GLOBALS)) {
+                $this->savedGlobals[$name] = $GLOBALS[$name];
+            }
+        }
+        Functions\when('wp_insert_post')->alias(function (array $post): int {
+            $this->inserted = $post;
+
+            return 77;
+        });
+        Functions\when('wp_delete_post')->alias(function (int $id, bool $force): WP_Post {
+            self::assertTrue($force, 'never to the trash');
+            $this->deleted[] = $id;
+
+            return new WP_Post(['ID' => $id]);
+        });
+        Functions\when('wp_mkdir_p')->alias(static fn (string $dir): bool => is_dir($dir) || @mkdir($dir, 0777, true));
+    }
+
+    protected function tearDown(): void
+    {
+        foreach (self::GLOBALS_CHANGED as $name) {
+            if (array_key_exists($name, $this->savedGlobals)) {
+                $GLOBALS[$name] = $this->savedGlobals[$name];
+            } else {
+                unset($GLOBALS[$name]);
+            }
+        }
+        self::removeTree($this->cacheRoot);
+        parent::tearDown();
+    }
+
+    private static function removeTree(string $path): void
+    {
+        foreach (glob(rtrim($path, '/') . '/{,.}*', GLOB_BRACE) ?: [] as $entry) {
+            if (in_array(basename($entry), ['.', '..'], true)) {
+                continue;
+            }
+            is_dir($entry) ? self::removeTree($entry) : unlink($entry);
+        }
+        @rmdir($path);
+    }
+
+    private function pageDir(): string
+    {
+        return $this->cacheRoot . 'supercache/example.test/lit-mcp-check-77/';
+    }
+
+    /** @param (Closure(int): void)|null $purge */
+    private function probe(?Closure $purge = null, ?Closure $cacheDir = null, bool $enabled = true): SuperCacheProbe
+    {
+        return new SuperCacheProbe(
+            static fn (): bool => $enabled,
+            $cacheDir ?? fn (int $id): string => $this->pageDir(),
+            $purge ?? fn (int $id) => unlink($this->pageDir() . 'index.html'),
+            function (int $id, string $status): bool {
+                $this->statuses[] = $id . ':' . $status;
+                if ($status === $this->throwingStatus) {
+                    throw new RuntimeException('Status kaputt');
+                }
+
+                return $status !== $this->refusedStatus;
+            }
+        );
+    }
+
+    /** Purge fake that does what WPSC does: the page's cache file disappears. */
+    private function purgingProbe(): SuperCacheProbe
+    {
+        return $this->probe(function (int $id): void {
+            self::assertFileExists($this->pageDir() . 'index.html', 'the file is there before the purge');
+            unlink($this->pageDir() . 'index.html');
+        });
+    }
+
+    /** Captures what Log writes to the PHP error log while $run runs. */
+    private function logged(Closure $run): string
+    {
+        $log = (string) tempnam(sys_get_temp_dir(), 'lit-mcp-log');
+        $previous = ini_set('error_log', $log);
+        try {
+            $run();
+
+            return (string) file_get_contents($log);
+        } finally {
+            ini_set('error_log', (string) $previous);
+            unlink($log);
+        }
+    }
+
+    public function testGreenWhenThePurgeRemovesTheCacheFileAndNothingIsLeftBehind(): void
+    {
+        self::assertSame([], $this->purgingProbe()->run());
+
+        self::assertDirectoryDoesNotExist($this->pageDir());
+        self::assertSame([77], $this->deleted);
+    }
+
+    public function testCreatesAMarkedDraftPageAndOnlyPassesThroughPrivateForThePurge(): void
+    {
+        $this->purgingProbe()->run();
+
+        self::assertSame('page', $this->inserted['post_type']);
+        self::assertSame('draft', $this->inserted['post_status']);
+        self::assertStringStartsWith(ThrowawayPost::TITLE, $this->inserted['post_title']);
+        self::assertSame([ThrowawayPost::MARKER => '1'], $this->inserted['meta_input']);
+        self::assertSame(['77:private', '77:draft'], $this->statuses);
+    }
+
+    public function testACacheFileThatSurvivesThePurgeIsAFixedTextAndIsRemovedAnyway(): void
+    {
+        $problems = [];
+        $logged = $this->logged(function () use (&$problems): void {
+            $problems = $this->probe(static fn (int $id) => null)->run();
+        });
+
+        self::assertSame(['Die Testdatei im Cache blieb nach dem Leeren durch WP Super Cache bestehen.'], $problems);
+        self::assertStringContainsString('lit-mcp-check-77', $logged);
+        self::assertDirectoryDoesNotExist($this->pageDir());
+        self::assertSame([77], $this->deleted);
+    }
+
+    public function testARenamedRebuildFileCountsAsPurgedAndIsCleanedUp(): void
+    {
+        $problems = $this->probe(function (int $id): void {
+            rename($this->pageDir() . 'index.html', $this->pageDir() . 'index.html.needs-rebuild');
+        })->run();
+
+        self::assertSame([], $problems);
+        self::assertDirectoryDoesNotExist($this->pageDir());
+    }
+
+    public function testADirectoryThePurgeAlreadyRemovedIsNoProblem(): void
+    {
+        $problems = $this->probe(function (int $id): void {
+            unlink($this->pageDir() . 'index.html');
+            rmdir($this->pageDir());
+        })->run();
+
+        self::assertSame([], $problems);
+    }
+
+    public function testAnExceptionOfThePurgeIsAFixedTextALogLineAndEverythingIsCleanedUp(): void
+    {
+        $problems = [];
+        $logged = $this->logged(function () use (&$problems): void {
+            $problems = $this->probe(static function (int $id): never {
+                throw new RuntimeException('WPSC kaputt');
+            })->run();
+        });
+
+        self::assertSame(['Super-Cache-Probe abgebrochen (Details im PHP-Error-Log).'], $problems);
+        self::assertStringContainsString('WPSC kaputt', $logged);
+        self::assertDirectoryDoesNotExist($this->pageDir());
+        self::assertSame([77], $this->deleted);
+        self::assertSame(['77:private', '77:draft'], $this->statuses);
+    }
+
+    public function testNothingToProbeWhileTheCacheIsSwitchedOff(): void
+    {
+        self::assertNull($this->probe(null, null, false)->run());
+        self::assertNull($this->inserted);
+    }
+
+    public function testNothingToProbeWithoutACachePathForThePage(): void
+    {
+        self::assertNull($this->probe(null, static fn (int $id): ?string => null)->run());
+        self::assertSame([77], $this->deleted);
+    }
+
+    public function testACacheDirectoryThatCannotBeCreatedIsAFixedText(): void
+    {
+        $blocker = $this->cacheRoot . 'blocker';
+        file_put_contents($blocker, 'x');
+        $problems = [];
+        $logged = $this->logged(function () use (&$problems, $blocker): void {
+            $problems = $this->probe(null, static fn (int $id): string => $blocker . '/seite/')->run();
+        });
+
+        self::assertSame(['Die Testdatei konnte nicht im Cache-Verzeichnis angelegt werden (Details im PHP-Error-Log).'], $problems);
+        self::assertStringContainsString('seite', $logged);
+        self::assertSame([77], $this->deleted);
+    }
+
+    public function testTheDefaultPurgeIsWpCachePostEdit(): void
+    {
+        Functions\expect('wp_cache_post_edit')->once()->with(77)->andReturnUsing(function (int $id): int {
+            unlink($this->pageDir() . 'index.html');
+
+            return $id;
+        });
+
+        $probe = new SuperCacheProbe(
+            static fn (): bool => true,
+            fn (int $id): string => $this->pageDir(),
+            null,
+            static fn (): bool => true
+        );
+
+        self::assertSame([], $probe->run());
+    }
+
+    public function testTheDefaultStatusSwitchWritesStatusAndSlugStraightToTheDatabaseWithoutHooks(): void
+    {
+        $wpdb = Mockery::mock();
+        $wpdb->posts = 'wp_posts';
+        $wpdb->expects('update')->with('wp_posts', ['post_status' => 'private', 'post_name' => 'lit-mcp-check-77'], ['ID' => 77])->andReturn(1);
+        $wpdb->expects('update')->with('wp_posts', ['post_status' => 'draft', 'post_name' => 'lit-mcp-check-77'], ['ID' => 77])->andReturn(1);
+        $GLOBALS['wpdb'] = $wpdb;
+        Functions\expect('clean_post_cache')->never();
+        $dropped = [];
+        Functions\when('wp_cache_delete')->alias(static function (int $id, string $group) use (&$dropped): bool {
+            $dropped[] = $group . ':' . $id;
+
+            return true;
+        });
+
+        $probe = new SuperCacheProbe(
+            static fn (): bool => true,
+            fn (int $id): string => $this->pageDir(),
+            fn (int $id) => unlink($this->pageDir() . 'index.html')
+        );
+
+        self::assertSame([], $probe->run());
+        self::assertSame(['posts:77', 'posts:77'], $dropped, 'the object cache must not keep the old status');
+    }
+
+    public function testTheDefaultEnabledCheckReadsTheWpscGlobal(): void
+    {
+        $GLOBALS['cache_enabled'] = false;
+        self::assertNull((new SuperCacheProbe())->run());
+
+        $GLOBALS['cache_enabled'] = null;
+        self::assertNull((new SuperCacheProbe())->run());
+    }
+
+    private function wpscDirs(string $home, string $current): void
+    {
+        Functions\when('get_supercache_dir')->justReturn($this->cacheRoot . 'supercache/' . $home . '/');
+        Functions\when('get_current_url_supercache_dir')->justReturn($this->cacheRoot . 'supercache/' . $current . '/');
+    }
+
+    public function testTheDefaultCachePathIsTheProbePageDirectoryBelowTheHomeHostDirectory(): void
+    {
+        $this->wpscDirs('example.test', 'example.test/lit-mcp-check-77');
+
+        self::assertSame($this->pageDir(), SuperCacheProbe::cacheDirFor(77));
+    }
+
+    /** WPSC derives the host from the request's Host header; the probe must not follow it somewhere else. */
+    public function testTheDefaultCachePathIsNullWhenWpscWouldUseAnotherHostThanTheHomeUrl(): void
+    {
+        $this->wpscDirs('example.test', 'www.example.test/lit-mcp-check-77');
+
+        self::assertNull(SuperCacheProbe::cacheDirFor(77));
+    }
+
+    public function testTheDefaultCachePathIsNullForAnythingButTheProbePageOfThisSite(): void
+    {
+        // A plain "?page_id=" address or an empty slug: WPSC resolves it to the home page's directory.
+        $this->wpscDirs('example.test', 'example.test');
+        self::assertNull(SuperCacheProbe::cacheDirFor(77));
+
+        $this->wpscDirs('example.test', 'example.test/seite');
+        self::assertNull(SuperCacheProbe::cacheDirFor(77));
+
+        $this->wpscDirs('example.test', 'example.test/lit-mcp-check-77/../../x');
+        self::assertNull(SuperCacheProbe::cacheDirFor(77));
+
+        $this->wpscDirs('example.test', 'example.test/lit-mcp-check-78');
+        self::assertNull(SuperCacheProbe::cacheDirFor(77));
+
+        Functions\when('get_current_url_supercache_dir')->justReturn('/var/www/html/lit-mcp-check-77/');
+        self::assertNull(SuperCacheProbe::cacheDirFor(77));
+    }
+
+    public function testTheDefaultCachePathIsNullWhenWpscKnowsNoDirectory(): void
+    {
+        Functions\when('get_supercache_dir')->justReturn(false);
+        Functions\when('get_current_url_supercache_dir')->justReturn(false);
+
+        self::assertNull(SuperCacheProbe::cacheDirFor(77));
+    }
+
+    public function testOnlyTheKnownCacheFilesOfTheProbePageAreRemoved(): void
+    {
+        $problems = $this->probe(function (int $id): void {
+            // What WPSC leaves after a rebuild-style purge, plus a file that is none of its names.
+            rename($this->pageDir() . 'index.html', $this->pageDir() . 'index.html.needs-rebuild');
+            touch($this->pageDir() . 'index-https.html');
+            touch($this->pageDir() . 'index-https.html.needs-rebuild');
+            touch($this->pageDir() . 'fremd.txt');
+        })->run();
+
+        self::assertSame([], $problems);
+        self::assertSame(['fremd.txt'], array_values(array_diff(scandir($this->pageDir()), ['.', '..'])));
+    }
+
+    public function testTheCacheDirectoryOfThePageIsRemovedWhenEmpty(): void
+    {
+        $this->purgingProbe()->run();
+
+        self::assertDirectoryDoesNotExist($this->pageDir());
+        self::assertDirectoryExists($this->cacheRoot . 'supercache/example.test/');
+    }
+
+    // --- P1: the purge must not empty the live cache ------------------------------------------------------------------
+
+    private function defaultPurgeProbe(): SuperCacheProbe
+    {
+        return new SuperCacheProbe(
+            static fn (): bool => true,
+            fn (int $id): string => $this->pageDir(),
+            null,
+            static fn (): bool => true
+        );
+    }
+
+    public function testTheDefaultPurgeRunsWithClearOnEditOffAndTheRelatedPagesFilterOffAndRestoresBoth(): void
+    {
+        $GLOBALS['wp_cache_clear_on_post_edit'] = 1;
+        $events = [];
+        $added = null;
+        Functions\expect('add_filter')->once()->with('wpsc_delete_related_pages_on_edit', Mockery::type(Closure::class), PHP_INT_MAX)
+            ->andReturnUsing(static function (string $hook, Closure $callback) use (&$events, &$added): bool {
+                $events[] = 'add_filter returning ' . var_export($callback(true), true);
+                $added = $callback;
+
+                return true;
+            });
+        Functions\expect('remove_filter')->once()->with('wpsc_delete_related_pages_on_edit', Mockery::type(Closure::class), PHP_INT_MAX)
+            ->andReturnUsing(static function (string $hook, Closure $callback) use (&$events, &$added): bool {
+                $events[] = $callback === $added ? 'remove_filter of the same callback' : 'remove_filter of ANOTHER callback';
+
+                return true;
+            });
+        Functions\expect('wp_cache_post_edit')->once()->with(77)->andReturnUsing(function (int $id) use (&$events): int {
+            $events[] = 'purge with clear_on_post_edit=' . var_export($GLOBALS['wp_cache_clear_on_post_edit'], true);
+            unlink($this->pageDir() . 'index.html');
+
+            return $id;
+        });
+
+        self::assertSame([], $this->defaultPurgeProbe()->run());
+
+        self::assertSame(
+            ['add_filter returning false', 'purge with clear_on_post_edit=0', 'remove_filter of the same callback'],
+            $events
+        );
+        self::assertSame(1, $GLOBALS['wp_cache_clear_on_post_edit']);
+    }
+
+    public function testTheDefaultPurgeLeavesAnUnsetClearOnEditGlobalUnset(): void
+    {
+        unset($GLOBALS['wp_cache_clear_on_post_edit']);
+        Functions\when('add_filter')->justReturn(true);
+        Functions\when('remove_filter')->justReturn(true);
+        Functions\expect('wp_cache_post_edit')->once()->andReturnUsing(function (int $id): int {
+            self::assertSame(0, $GLOBALS['wp_cache_clear_on_post_edit']);
+            unlink($this->pageDir() . 'index.html');
+
+            return $id;
+        });
+
+        self::assertSame([], $this->defaultPurgeProbe()->run());
+        self::assertArrayNotHasKey('wp_cache_clear_on_post_edit', $GLOBALS);
+    }
+
+    public function testTheDefaultPurgeRestoresGlobalAndFilterWhenWpscThrows(): void
+    {
+        $GLOBALS['wp_cache_clear_on_post_edit'] = '1';
+        Functions\expect('add_filter')->once()->andReturn(true);
+        Functions\expect('remove_filter')->once()->with('wpsc_delete_related_pages_on_edit', Mockery::type(Closure::class), PHP_INT_MAX)->andReturn(true);
+        Functions\expect('wp_cache_post_edit')->once()->andThrow(new RuntimeException('WPSC kaputt'));
+
+        $problems = [];
+        $this->logged(function () use (&$problems): void {
+            $problems = $this->defaultPurgeProbe()->run();
+        });
+
+        self::assertSame(['Super-Cache-Probe abgebrochen (Details im PHP-Error-Log).'], $problems);
+        self::assertSame('1', $GLOBALS['wp_cache_clear_on_post_edit']);
+    }
+
+    // --- P2: a status the database refused is no purge result ---------------------------------------------------------
+
+    public function testARefusedPrivateStatusIsItsOwnFixedProblemAndTheProbeNeverPurges(): void
+    {
+        $this->refusedStatus = 'private';
+        $purged = false;
+        $problems = [];
+        $logged = $this->logged(function () use (&$problems, &$purged): void {
+            $problems = $this->probe(static function (int $id) use (&$purged): void {
+                $purged = true;
+            })->run();
+        });
+
+        self::assertSame(['Der Status der Testseite konnte nicht gesetzt werden (Details im PHP-Error-Log).'], $problems);
+        self::assertStringContainsString('77', $logged);
+        self::assertStringContainsString('private', $logged);
+        self::assertFalse($purged);
+        self::assertSame([77], $this->deleted);
+        self::assertSame(['77:private', '77:draft'], $this->statuses);
+    }
+
+    /** @return array<string, array{0: int|false}> */
+    public static function refusedUpdates(): array
+    {
+        return ['database error' => [false], 'no row changed' => [0]];
+    }
+
+    /** @dataProvider refusedUpdates */
+    public function testTheDefaultStatusSwitchTreatsAFailedOrEmptyUpdateAsRefused(int|false $result): void
+    {
+        $wpdb = Mockery::mock();
+        $wpdb->posts = 'wp_posts';
+        $wpdb->shouldReceive('update')->andReturn($result);
+        $GLOBALS['wpdb'] = $wpdb;
+        Functions\when('wp_cache_delete')->justReturn(true);
+        Functions\expect('wp_cache_post_edit')->never();
+
+        $problems = [];
+        $this->logged(function () use (&$problems): void {
+            $problems = (new SuperCacheProbe(
+                static fn (): bool => true,
+                fn (int $id): string => $this->pageDir(),
+                fn (int $id) => null
+            ))->run();
+        });
+
+        self::assertSame(['Der Status der Testseite konnte nicht gesetzt werden (Details im PHP-Error-Log).'], $problems);
+        self::assertSame([77], $this->deleted);
+    }
+
+    public function testAFailingResetToDraftNeitherHidesTheResultNorEndsTheCheck(): void
+    {
+        $this->throwingStatus = 'draft';
+        $problems = [];
+        $logged = $this->logged(function () use (&$problems): void {
+            $problems = $this->purgingProbe()->run();
+        });
+
+        self::assertSame([], $problems);
+        self::assertStringContainsString('Status kaputt', $logged);
+        self::assertSame([77], $this->deleted);
+        self::assertDirectoryDoesNotExist($this->pageDir());
+    }
+
+    public function testAFailingResetToDraftDoesNotReplaceAnExceptionOfThePurge(): void
+    {
+        $this->throwingStatus = 'draft';
+        $problems = [];
+        $logged = $this->logged(function () use (&$problems): void {
+            $problems = $this->probe(static function (int $id): never {
+                throw new RuntimeException('WPSC kaputt');
+            })->run();
+        });
+
+        self::assertSame(['Super-Cache-Probe abgebrochen (Details im PHP-Error-Log).'], $problems);
+        self::assertStringContainsString('WPSC kaputt', $logged);
+        self::assertSame([77], $this->deleted);
+    }
+
+    public function testARefusedResetToDraftIsLoggedOnly(): void
+    {
+        $this->refusedStatus = 'draft';
+        $problems = [];
+        $logged = $this->logged(function () use (&$problems): void {
+            $problems = $this->purgingProbe()->run();
+        });
+
+        self::assertSame([], $problems);
+        self::assertStringContainsString('draft', $logged);
+    }
+}

tests/Unit/PluginTest.php

@@ -53,13 +53,13 @@ final class PluginTest extends TestCase
         );
     }
 
-    /** Divi and Pods boot (hooks, orphan cleanup); a second boot registers nothing twice. */
+    /** Divi, Pods and WP Super Cache boot (hooks, orphan cleanup); a second boot registers nothing twice. */
     public function testTheBootableIntegrationsBootExactlyOnce(): void
     {
         Actions\expectAdded('upgrader_process_complete')->once();
         Actions\expectAdded('lit_mcp_compat_changed')->once();
         Filters\expectAdded(SettingsPage::TABS_FILTER)->never();
-        Actions\expectAdded(CompatibilityTab::LOAD_ACTION)->times(2); // Divi and Pods
+        Actions\expectAdded(CompatibilityTab::LOAD_ACTION)->times(3); // Divi, Pods and WP Super Cache
         Actions\expectAdded(CompatibilityTab::EXTRA_ACTION)->once();
         Filters\expectAdded(CompatibilityTab::COLUMNS_FILTER)->once();
         $registry = self::registry();