SSR health: alert mails on ok/down transitions + auto-failover to SPA after N consecutive misses (SSR_ALERT_EMAIL / SSR_FAILOVER_AFTER in var/vitec-ssr-purge.env)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/vitec/Classes/Service/SsrFlagService.php

@@ -4,9 +4,11 @@ declare(strict_types=1);
 
 namespace Evomedien\Vitec\Service;
 
+use TYPO3\CMS\Core\Cache\CacheManager;
 use TYPO3\CMS\Core\Core\Environment;
 use TYPO3\CMS\Core\Exception\SiteNotFoundException;
 use TYPO3\CMS\Core\Site\SiteFinder;
+use TYPO3\CMS\Core\Utility\GeneralUtility;
 
 /**
  * Keeps the SSR routing flag file in sync with the site setting
@@ -91,6 +93,48 @@ final class SsrFlagService
         return $desired;
     }
 
+    /**
+     * Auto-failover (vitec:ssr-health): turns SSR delivery hard OFF.
+     *
+     * Removing only the flag file would not stick - the self-healing
+     * SyncSsrFlag middleware recreates it from the still-true site setting
+     * on the very next request. So the setting itself is flipped to false
+     * in config/sites/<identifier>/settings.yaml (the file the backend
+     * settings editor writes, flat dotted keys), caches are flushed so the
+     * compiled site settings forget the old value, and only then the flag
+     * is removed. Re-enabling is deliberately manual (backend switch or
+     * settings.yaml + cache flush).
+     */
+    public function disableSsr(): void
+    {
+        $changed = false;
+        foreach ($this->siteFinder->getAllSites() as $site) {
+            $file = Environment::getConfigPath() . '/sites/' . $site->getIdentifier() . '/settings.yaml';
+            if (!is_file($file)) {
+                continue;
+            }
+            $yaml = (string)file_get_contents($file);
+            $new = preg_replace('/^(vitec\.ssr\.enabled\s*:).*$/m', '$1 false', $yaml, 1, $count);
+            if ($new !== null && $count > 0 && $new !== $yaml) {
+                if (file_put_contents($file, $new) === false) {
+                    throw new \RuntimeException('Could not write ' . $file, 1762800001);
+                }
+                $changed = true;
+            }
+        }
+        if (!$changed && $this->isEnabledInSettings()) {
+            throw new \RuntimeException(
+                'vitec.ssr.enabled not found in any config/sites/*/settings.yaml - cannot disable it, '
+                . 'and the SyncSsrFlag middleware would recreate the flag from the setting',
+                1762800002
+            );
+        }
+        if ($changed) {
+            GeneralUtility::makeInstance(CacheManager::class)->flushCaches();
+        }
+        @unlink($this->getFlagPath());
+    }
+
     /**
      * Sync variant for the request hot path: never lets an IO hiccup
      * (read-only FS, concurrent unlink ...) break request handling.