diff --git a/.github/workflows/runtime-regressions.yml b/.github/workflows/runtime-regressions.yml
new file mode 100644
index 0000000..035048a
--- /dev/null
+++ b/.github/workflows/runtime-regressions.yml
@@ -0,0 +1,29 @@
+name: Runtime regressions
+on: [push, pull_request]
+jobs:
+  runtime:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php: ['8.4', '8.5']
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/checkout@v4
+        with:
+          repository: evolution-cms/evolution
+          ref: 3.6.x
+          path: .test-core
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: mbstring, dom, xml, sqlite3, pdo_sqlite, gd, intl, zip
+          coverage: none
+      - run: composer install --working-dir=.test-core/core --no-interaction --no-scripts --prefer-dist
+      - name: Run package regression scripts
+        env:
+          SGALLERY_AUTOLOAD: ${{ github.workspace }}/.test-core/core/vendor/autoload.php
+          SCOMMERCE_TEST_AUTOLOAD: ${{ github.workspace }}/.test-core/core/vendor/autoload.php
+          PACKAGE_AUTOLOAD: ${{ github.workspace }}/.test-core/core/vendor/autoload.php
+        run: |
+          for test in tests/runtime/*-test.php; do php "$test"; done
+          php tests/resource-aliases.php
diff --git a/plugins/sMultisitePlugin.php b/plugins/sMultisitePlugin.php
index 7599a41..93b6c47 100644
--- a/plugins/sMultisitePlugin.php
+++ b/plugins/sMultisitePlugin.php
@@ -32,21 +32,17 @@
      * migrations have created the table. SQLite fails immediately in that
      * state, so runtime listeners must stay in default-mode until migrations
      * finish.
-     * The result is memoized for the current PHP request to avoid repeated
-     * information_schema queries from product-card rendering.
+     * Positive checks use a database-scoped shared cache invalidated by
+     * migrations and cache flush. Missing tables are never cached, so
+     * installation can create the table and retry in the same PHP process.
      *
      * @return bool
      */
     function ms_multisite_table_ready(): bool {
-        static $ready;
-        if (isset($ready)) {
-            return $ready;
-        }
-
         try {
-            return $ready = Schema::hasTable('s_multisites');
+            return \Seiger\sMultisite\Support\ActiveDomainCache::tableReady();
         } catch (\Throwable) {
-            return $ready = false;
+            return false;
         }
     }
 }
@@ -212,7 +208,7 @@ function ms_sso_current_session_id(): string {
  * @return void
  */
 Event::listen('evolution.OnLoadSettings', function($params) {
-    $host = $_SERVER['HTTP_HOST'];
+    $host = $_SERVER['HTTP_HOST'] ?? null;
     if (isset($params['config']['setHost']) && trim($params['config']['setHost']) !== '') {
         $host = trim($params['config']['setHost']);
     }
@@ -222,7 +218,7 @@ function ms_sso_current_session_id(): string {
     if (!ms_multisite_table_ready()) {
         return;
     }
-    $domain = \Seiger\sMultisite\Models\sMultisite::whereDomain($host)->whereActive(1)->first();
+    $domain = \Seiger\sMultisite\Support\ActiveDomainCache::find($host);
     if ($domain) {
         evo()->setConfig('site_key', $domain->key);
         evo()->setConfig('site_name', $domain->site_name);
diff --git a/src/Support/ActiveDomainCache.php b/src/Support/ActiveDomainCache.php
new file mode 100644
index 0000000..150cb1c
--- /dev/null
+++ b/src/Support/ActiveDomainCache.php
@@ -0,0 +1,155 @@
+<?php namespace Seiger\sMultisite\Support;
+
+use Illuminate\Database\Events\QueryExecuted;
+use Illuminate\Database\Events\TransactionCommitted;
+use Illuminate\Database\Events\TransactionRolledBack;
+use Illuminate\Support\Facades\Cache;
+use Seiger\sMultisite\Models\sMultisite;
+
+/**
+ * Cache exact-host active-domain lookups without serializing model dates.
+ * Generation keys prevent in-flight reads from restoring invalidated entries.
+ *
+ * @since 1.2.0
+ */
+final class ActiveDomainCache
+{
+    /** @var \WeakMap<\Illuminate\Database\Connection, string>|null Isolate ephemeral SQLite databases. */
+    private static ?\WeakMap $memoryDatabases = null;
+
+    /**
+     * Scope generations to the actual database and prefixed package table.
+     *
+     * @param \Illuminate\Database\Connection $connection
+     * @return string
+     * @since 1.2.0
+     */
+    private static function key($connection): string
+    {
+        $database = (string)$connection->getDatabaseName();
+        $memoryScope = null;
+        if ($connection->getDriverName() === 'sqlite'
+            && ($database === '' || str_contains($database, ':memory:') || str_contains($database, 'mode=memory'))) {
+            self::$memoryDatabases ??= new \WeakMap();
+            $memoryScope = self::$memoryDatabases[$connection] ??= bin2hex(random_bytes(16));
+        }
+        return 'sMultisite.active-domain.v1.' . hash('sha256', serialize([
+            $connection->getName(), $connection->getConfig('driver'), $connection->getConfig('host'),
+            $connection->getConfig('port'), $connection->getConfig('unix_socket'),
+            $connection->getDatabaseName(), $connection->getTablePrefix(), $memoryScope,
+        ]));
+    }
+
+    /**
+     * Observe model, builder and raw SQL writes, including comments and CTE prefixes.
+     * Clear again after the outer transaction ends to discard concurrent old reads.
+     *
+     * @param \Illuminate\Contracts\Events\Dispatcher $events
+     * @return void
+     * @since 1.2.0
+     */
+    public static function listen($events): void
+    {
+        $dirty = [];
+        foreach ([\Illuminate\Database\Events\MigrationEnded::class,
+            \Illuminate\Database\Events\MigrationsEnded::class] as $event) {
+            $events->listen($event, static function (): void {
+                $connection = (new sMultisite())->getConnection();
+                Cache::forget(self::key($connection) . '.table_ready');
+                Cache::forget(self::key($connection));
+            });
+        }
+        $events->listen(QueryExecuted::class, static function ($event) use (&$dirty): void {
+            $table = preg_quote($event->connection->getTablePrefix() . 's_multisites', '~');
+            if (!preg_match('~\b(?:insert|update|delete|replace|truncate|create|alter|drop|rename)\b~i', $event->sql)
+                || !preg_match('~(?<![a-z0-9_])' . $table . '(?![a-z0-9_])~i', $event->sql)) {
+                return;
+            }
+            if (preg_match('~\b(?:create|alter|drop|rename)\b~i', $event->sql)) {
+                Cache::forget(self::key($event->connection) . '.table_ready');
+            }
+            Cache::forget(self::key($event->connection));
+            if ($event->connection->transactionLevel() > 0) {
+                $dirty[spl_object_id($event->connection)] = true;
+            }
+        });
+        foreach ([TransactionCommitted::class, TransactionRolledBack::class] as $event) {
+            $events->listen($event, static function ($event) use (&$dirty): void {
+                $id = spl_object_id($event->connection);
+                if (isset($dirty[$id]) && $event->connection->transactionLevel() === 0) {
+                    Cache::forget(self::key($event->connection));
+                    Cache::forget(self::key($event->connection) . '.table_ready');
+                    unset($dirty[$id]);
+                }
+            });
+        }
+    }
+
+    /**
+     * Cache only a successful schema check, scoped to the model's database.
+     * Missing tables are checked again on the next call, including installation
+     * in the same process. Transactions never publish uncommitted schema state.
+     * Read the shared readiness entry on each call so direct Cache::flush() takes
+     * effect even when the backend emits no flush event. Migrations and observed
+     * DDL remove the positive entry; TTL bounds externally changed schemas.
+     *
+     * @return bool Whether the multisite table currently exists.
+     * @since 1.2.0
+     */
+    public static function tableReady(): bool
+    {
+        $connection = (new sMultisite())->getConnection();
+        $key = self::key($connection) . '.table_ready';
+        $transaction = $connection->transactionLevel() > 0;
+        if (!$transaction && Cache::get($key) === true) {
+            return true;
+        }
+        $ready = $connection->getSchemaBuilder()->hasTable('s_multisites');
+        if ($ready && !$transaction) {
+            Cache::put($key, true, 300);
+        }
+        return $ready;
+    }
+
+    /**
+     * Resolve the caller's unchanged host, including OnLoadSettings setHost overrides.
+     * Cache misses in an envelope; bypass shared state inside transactions. A five
+     * minute TTL also bounds staleness for writes made outside this application.
+     *
+     * CLI may have no host: retain the original whereDomain(null) lookup and
+     * bypass shared host caching rather than treating null as an empty domain.
+     * Custom global scopes and retrieved observers retain their original database path.
+     *
+     * @param string|null $host Exact host used by the existing domain query, or null in CLI.
+     * @return sMultisite|null
+     * @since 1.2.0
+     */
+    public static function find(?string $host): ?sMultisite
+    {
+        $model = new sMultisite();
+        $connection = $model->getConnection();
+        $read = static fn () => sMultisite::whereDomain($host)->whereActive(1)->first();
+        // Custom scopes/observers may depend on context outside the exact host.
+        $events = $model->getEventDispatcher();
+        if ($host === null || $connection->transactionLevel() > 0
+            || $model->getGlobalScopes() !== []
+            || ($events && $events->hasListeners('eloquent.retrieved: ' . sMultisite::class))) {
+            return $read();
+        }
+
+        $key = self::key($connection);
+        $generation = Cache::remember($key, 300, static fn () => bin2hex(random_bytes(16)));
+        $entryKey = $key . '.' . $generation . '.' . hash('sha256', $host);
+        $entry = Cache::get($entryKey);
+        if (is_array($entry) && array_key_exists('attributes', $entry)) {
+            return $entry['attributes'] === null ? null
+                : $model->newFromBuilder($entry['attributes'], $connection->getName());
+        }
+
+        // Return the queried model on a miss so retrieved observers fire only once.
+        $domain = $read();
+        Cache::put($entryKey, ['attributes' => $domain?->getRawOriginal()], 300);
+        return $domain;
+    }
+
+}
diff --git a/src/sMultisiteServiceProvider.php b/src/sMultisiteServiceProvider.php
index d85dd7c..16eddaa 100644
--- a/src/sMultisiteServiceProvider.php
+++ b/src/sMultisiteServiceProvider.php
@@ -73,12 +73,14 @@ public function boot()
     /**
      * Register bindings and services in the container.
      *
-     * This method is used to bind classes or interfaces into the service container.
+     * Bindings retain the existing package lifecycle; domain cache invalidation observes
+     * writes from manager, frontend, migrations and CLI before plugins run.
      *
      * @return void
      */
     public function register()
     {
+        \Seiger\sMultisite\Support\ActiveDomainCache::listen($this->app['events']);
         // Add plugins to Evolution CMS
         $this->loadPluginsFrom(dirname(__DIR__) . '/plugins/');
         $this->app->singleton(sMultisite::class);
diff --git a/tests/runtime/README.md b/tests/runtime/README.md
new file mode 100644
index 0000000..028d080
--- /dev/null
+++ b/tests/runtime/README.md
@@ -0,0 +1,7 @@
+# Runtime regression checks
+
+Run each `*-test.php` with `PACKAGE_AUTOLOAD` pointing at an installed Evolution CMS 3.6.x `core/vendor/autoload.php`. The test bootstrap loads this package from the checkout ahead of any consumer classmap. Fixtures use isolated SQLite databases and temporary files; no site database is used. The CI matrix executes PHP 8.4 and 8.5.
+
+Shared entries use a five-minute TTL. Observed application writes invalidate immediately; writes made directly outside the application require a cache clear for immediate visibility. Transactions bypass shared entries and invalidate again after the outer commit/rollback.
+
+Custom model scopes and retrieved observers keep the uncached database path, because they may depend on state not represented by the package cache key.
diff --git a/tests/runtime/bootstrap.php b/tests/runtime/bootstrap.php
new file mode 100644
index 0000000..8715379
--- /dev/null
+++ b/tests/runtime/bootstrap.php
@@ -0,0 +1,24 @@
+<?php
+
+// Load a caller-supplied Evolution dependency tree without coupling tests to a site.
+$autoload = getenv('PACKAGE_AUTOLOAD') ?: dirname(__DIR__, 2) . '/vendor/autoload.php';
+if (!is_file($autoload)) {
+    throw new RuntimeException('Set PACKAGE_AUTOLOAD to an Evolution CMS core vendor/autoload.php');
+}
+require $autoload;
+spl_autoload_register(static function (string $class): void {
+    $prefix = 'Seiger\sMultisite\\';
+    if (str_starts_with($class, $prefix)) {
+        $file = dirname(__DIR__, 2) . '/src/' . str_replace('\\', '/', substr($class, strlen($prefix))) . '.php';
+        if (is_file($file)) {
+            require $file;
+        }
+    }
+}, true, true);
+// Make warnings and PHP-version deprecations visible as regression failures.
+set_error_handler(static function (int $severity, string $message, string $file, int $line): bool {
+    if (!(error_reporting() & $severity)) {
+        return false;
+    }
+    throw new ErrorException($message, 0, $severity, $file, $line);
+});
diff --git a/tests/runtime/domain-cache-test.php b/tests/runtime/domain-cache-test.php
new file mode 100644
index 0000000..a7def2a
--- /dev/null
+++ b/tests/runtime/domain-cache-test.php
@@ -0,0 +1,193 @@
+<?php
+
+use Illuminate\Support\Facades\Cache;
+/**
+ * Support isolated package assertions without a site bootstrap.
+ *
+ * @since 1.2.0
+ */
+function evo()
+{
+    return $GLOBALS['evo'];
+}
+/**
+ * Support isolated package assertions without a site bootstrap.
+ *
+ * @since 1.2.0
+ */
+function ms_multisite_table_ready()
+{
+    return \Seiger\sMultisite\Support\ActiveDomainCache::tableReady();
+}
+require __DIR__ . '/bootstrap.php';
+use Seiger\sMultisite\Support\ActiveDomainCache as C;
+use Seiger\sMultisite\Models\sMultisite as M;
+$app = new Illuminate\Container\Container();
+Illuminate\Support\Facades\Facade::setFacadeApplication($app);
+$events = new Illuminate\Events\Dispatcher($app);
+$app->instance('events', $events);
+$app->instance('cache', new Illuminate\Cache\Repository(new Illuminate\Cache\FileStore(new Illuminate\Filesystem\Filesystem(), sys_get_temp_dir() . '/ewt-domain-cache-check-' . getmypid())));
+$db = new Illuminate\Database\Capsule\Manager();
+$db->addConnection(['driver' => 'sqlite', 'database' => ':memory:', 'prefix' => 'evo_']);
+$db->setEventDispatcher($events);
+$db->setAsGlobal();
+$db->bootEloquent();
+$c = $db->getConnection();
+$c->statement('CREATE TABLE evo_s_multisites (id INTEGER PRIMARY KEY, domain TEXT, active INTEGER, resource INTEGER, "key" TEXT, site_name TEXT, site_start INTEGER, error_page INTEGER, unauthorized_page INTEGER, site_color TEXT, created_at TEXT, updated_at TEXT)');
+C::listen($events);
+foreach (['a.test', 'b.test'] as $i => $host) {
+    $c->table('s_multisites')->insert(['id' => $i + 1, 'domain' => $host, 'active' => 1, 'resource' => $i + 10, 'key' => 'site' . $i, 'site_name' => 'Site ' . $i, 'site_start' => $i + 20, 'error_page' => 4, 'unauthorized_page' => 5, 'site_color' => 'blue']);
+}
+/**
+ * Support isolated package assertions without a site bootstrap.
+ *
+ * @since 1.2.0
+ */
+function check($ok, $label)
+{
+    if (!$ok) {
+        throw new RuntimeException($label);
+    }
+    echo "OK {$label}\n";
+}
+$c->enableQueryLog();
+check(C::find('a.test')->site_start === 20, 'cold lookup and integer casts');
+$c->flushQueryLog();
+check(C::find('a.test')->key === 'site0' && count($c->getQueryLog()) === 0, 'warm lookup skips SQL');
+$retrieved = 0;
+M::retrieved(static function () use (&$retrieved): void {
+    ++$retrieved;
+});
+C::find('a.test');
+C::find('a.test');
+check($retrieved === 2, 'retrieved observers run once per lookup');
+$events->forget('eloquent.retrieved: ' . M::class);
+$decorate = true;
+M::retrieved(static function ($model) use (&$decorate): void {
+    if ($decorate) {
+        $model->site_name = 'decorated:' . $model->site_name;
+    }
+});
+Cache::flush();
+$firstDecorated = C::find('a.test')->site_name;
+check($firstDecorated === 'decorated:Site 0' && C::find('a.test')->site_name === $firstDecorated, 'retrieved observer transformations run once on original attributes');
+$decorate = false;
+$events->forget('eloquent.retrieved: ' . M::class);
+$c->statement("/* manager edit */ UPDATE evo_s_multisites SET site_name = 'Commented' WHERE id = 1");
+check(C::find('a.test')->site_name === 'Commented', 'comment-prefixed writes invalidate');
+$c->statement("WITH chosen AS (SELECT 1 AS id) UPDATE evo_s_multisites SET site_name = 'CTE' WHERE id IN (SELECT id FROM chosen)");
+check(C::find('a.test')->site_name === 'CTE', 'CTE-prefixed writes invalidate');
+$scopes = M::getAllGlobalScopes();
+M::addGlobalScope('deny', static fn($query) => $query->whereRaw('0 = 1'));
+check(C::find('a.test') === null, 'custom scopes bypass shared domain entries');
+M::setAllGlobalScopes($scopes);
+C::find('missing.test');
+$c->flushQueryLog();
+check(C::find('missing.test') === null && count($c->getQueryLog()) === 0, 'missing domain cached');
+$c->table('s_multisites')->where('id', 1)->update(['domain' => 'renamed.test', 'site_name' => 'Renamed']);
+check(C::find('a.test') === null && C::find('renamed.test')->site_name === 'Renamed', 'rename and fields invalidated');
+$c->table('s_multisites')->where('id', 1)->update(['active' => 0]);
+check(C::find('renamed.test') === null, 'deactivation invalidated');
+$c->table('s_multisites')->where('id', 1)->update(['active' => 1]);
+check(C::find('renamed.test') !== null, 'activation invalidated');
+$c->beginTransaction();
+$c->table('s_multisites')->where('id', 1)->update(['site_name' => 'Uncommitted']);
+check(C::find('renamed.test')->site_name === 'Uncommitted', 'transaction bypass');
+$c->rollBack();
+check(C::find('renamed.test')->site_name === 'Renamed', 'rollback invalidation');
+$c->beginTransaction();
+$c->table('s_multisites')->where('id', 1)->update(['site_name' => 'Committed']);
+$c->commit();
+check(C::find('renamed.test')->site_name === 'Committed', 'commit invalidation');
+$m = M::find(1);
+$m->site_name = 'Model update';
+$m->save();
+check(C::find('renamed.test')->site_name === 'Model update', 'model editing invalidation');
+$m->delete();
+check(C::find('renamed.test') === null, 'model deletion invalidation');
+$evo = new class
+{
+    public array $config = [];
+    /**
+     * Record settings written by the actual package listener.
+     *
+     * @since 1.2.0
+     */
+    function setConfig($k, $v)
+    {
+        $this->config[$k] = $v;
+    }
+    /**
+     * Expose only the controlled configuration used by this isolated regression.
+     *
+     * @since 1.2.0
+     */
+    function getConfig($k, $default = null)
+    {
+        return $this->config[$k] ?? $default;
+    }
+};
+// Exercise the actual listener; the URL facade is unused when no root binding exists.
+$processor = new stdClass();
+$app->instance('UrlProcessor', $processor);
+$source = file_get_contents(dirname(__DIR__, 2) . '/plugins/sMultisitePlugin.php');
+$start = strpos($source, "Event::listen('evolution.OnLoadSettings'");
+$end = strpos($source, "\n});", $start) + 4;
+$listener = substr($source, $start, $end - $start);
+eval('use Illuminate\Support\Facades\Event; use Illuminate\Support\Facades\Cache; use EvolutionCMS\Facades\UrlProcessor;' . $listener);
+$_SERVER['HTTP_HOST'] = 'unknown.test';
+$params = ['config' => ['setHost' => ' b.test ']];
+$events->dispatch('evolution.OnLoadSettings', [$params]);
+check($evo->config['site_key'] === 'site1' && $evo->config['site_start'] === 21, 'setHost selects trimmed override');
+$events->dispatch('evolution.OnLoadSettings', [['config' => []]]);
+check($evo->config['site_key'] === 'default' && $evo->config['site_root'] === 0, 'unknown host preserves defaults');
+echo "ALL DOMAIN CACHE CHECKS PASSED\n";
+unset($_SERVER['HTTP_HOST']);
+$events->dispatch('evolution.OnLoadSettings', [['config' => []]]);
+check($evo->config['site_key'] === 'default', 'CLI missing host preserves defaults');
+$events->dispatch('evolution.OnLoadSettings', [['config' => ['setHost' => ' b.test ']]]);
+check($evo->config['site_key'] === 'site1', 'CLI setHost override still works');
+$c->table('s_multisites')->insert(['id' => 3, 'domain' => null, 'active' => 1, 'key' => 'null-domain']);
+$c->table('s_multisites')->insert(['id' => 4, 'domain' => '', 'active' => 1, 'key' => 'empty-domain']);
+check(C::find(null)?->key === 'null-domain', 'null keeps original whereDomain(null) semantics');
+check(C::find('')?->key === 'empty-domain', 'empty host remains distinct from null');
+$c->flushQueryLog();
+C::find(null);
+check(count($c->getQueryLog()) === 1, 'hostless lookup bypasses shared host cache');
+$c->flushQueryLog();
+check(C::tableReady(), 'cold table check');
+$c->flushQueryLog();
+check(C::tableReady() && count($c->getQueryLog()) === 0, 'warm table check skips SQL');
+$events->dispatch(new Illuminate\Database\Events\MigrationsEnded('up'));
+$c->flushQueryLog();
+C::tableReady();
+check(count($c->getQueryLog()) > 0, 'migration completion invalidates');
+$events->dispatch(new Illuminate\Database\Events\MigrationEnded(new class extends Illuminate\Database\Migrations\Migration
+{
+}, 'down'));
+$c->flushQueryLog();
+C::tableReady();
+check(count($c->getQueryLog()) > 0, 'single migration completion invalidates');
+Illuminate\Support\Facades\Cache::flush();
+$c->flushQueryLog();
+C::tableReady();
+check(count($c->getQueryLog()) > 0, 'cache flush invalidates');
+$c->beginTransaction();
+$c->statement('DROP TABLE evo_s_multisites');
+check(!C::tableReady(), 'uncommitted drop bypasses positive cache');
+$c->rollBack();
+check(C::tableReady(), 'rollback restores availability');
+$c->statement('DROP TABLE evo_s_multisites');
+$c->flushQueryLog();
+check(!C::tableReady() && !C::tableReady() && count($c->getQueryLog()) >= 2, 'negative result not cached');
+$c->statement('CREATE TABLE evo_s_multisites (id INTEGER PRIMARY KEY)');
+check(C::tableReady(), 'create after missing in same process');
+$c->flushQueryLog();
+check(C::tableReady() && count($c->getQueryLog()) === 0, 'created table warmed');
+echo "ALL TABLE READINESS CHECKS PASSED\n";
+$other = new Illuminate\Database\SQLiteConnection(new PDO('sqlite::memory:'), ':memory:', 'evo_', $c->getConfig());
+$keyMethod = new ReflectionMethod(C::class, 'key');
+$originalKey = $keyMethod->invoke(null, $c);
+// Normalize the connection name as well: identity must still follow the ephemeral database.
+
+check($originalKey !== $keyMethod->invoke(null, $other), 'identical in-memory SQLite configurations have isolated cache identities');