diff --git a/lib/Horde/Core/Mime/Viewer/Vcard.php b/lib/Horde/Core/Mime/Viewer/Vcard.php
index 72a5b069..98966f4c 100644
--- a/lib/Horde/Core/Mime/Viewer/Vcard.php
+++ b/lib/Horde/Core/Mime/Viewer/Vcard.php
@@ -166,7 +166,7 @@ protected function _renderInline()
                 $birthday = new Horde_Date($birthdays[0]);
                 $html .= $this->_row(
                     Horde_Core_Translation::t('Birthday'),
-                    $birthday->strftime($prefs->getValue('date_format'))
+                    $birthday->format($prefs->getValue('date_format'), new \Horde\Date\Formatter\IcuFormatter(), $GLOBALS['language'] ?? 'en_US')
                 );
             } catch (Horde_Icalendar_Exception $e) {
             }
diff --git a/src/Factory/DateFormatPrefsFactory.php b/src/Factory/DateFormatPrefsFactory.php
new file mode 100644
index 00000000..69e23d9d
--- /dev/null
+++ b/src/Factory/DateFormatPrefsFactory.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright 2026 The Horde Project (http://www.horde.org/)
+ *
+ * See the enclosed file LICENSE for license information (LGPL). If you
+ * did not receive this file, see http://www.horde.org/licenses/lgpl21.
+ *
+ * @category  Horde
+ * @copyright 2026 The Horde Project
+ * @license   http://www.horde.org/licenses/lgpl21 LGPL 2.1
+ * @package   Core
+ */
+
+namespace Horde\Core\Factory;
+
+use Horde\Core\Prefs\DateFormatPrefs;
+use Horde_Injector;
+use Psr\Log\LoggerInterface;
+use Psr\Log\NullLogger;
+
+/**
+ * Factory for DateFormatPrefs
+ *
+ * @category  Horde
+ * @copyright 2026 The Horde Project
+ * @license   http://www.horde.org/licenses/lgpl21 LGPL 2.1
+ * @package   Core
+ */
+class DateFormatPrefsFactory
+{
+    public function create(Horde_Injector $injector): DateFormatPrefs
+    {
+        $logger = null;
+        try {
+            $logger = $injector->getInstance(LoggerInterface::class);
+        } catch (\Throwable) {
+            // Logger unavailable — proceed without
+        }
+
+        return new DateFormatPrefs(
+            prefs: $injector->getInstance('Horde_Prefs'),
+            locale: $GLOBALS['language'] ?? 'en_US',
+            logger: $logger,
+        );
+    }
+}
diff --git a/src/Middleware/AuthHordeSession.php b/src/Middleware/AuthHordeSession.php
index 8c49eeb0..8a80f2f6 100644
--- a/src/Middleware/AuthHordeSession.php
+++ b/src/Middleware/AuthHordeSession.php
@@ -37,7 +37,8 @@ public function __construct(Horde_Registry $registry)
 
     public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
     {
-        if ($this->registry->isAuthenticated()) {
+        $isAuth = $this->registry->isAuthenticated();
+        if ($isAuth) {
             $request = $request->withAttribute('HORDE_AUTHENTICATED_USER', $this->registry->getAuth());
             $request = $request->withoutAttribute('HORDE_GUEST');
         } else {
diff --git a/src/Middleware/RedirectToLogin.php b/src/Middleware/RedirectToLogin.php
index 562dd88f..8e3911f4 100644
--- a/src/Middleware/RedirectToLogin.php
+++ b/src/Middleware/RedirectToLogin.php
@@ -50,15 +50,18 @@ public function process(ServerRequestInterface $request, RequestHandlerInterface
         $user = $request->getAttribute('HORDE_AUTHENTICATED_USER');
         $app = $request->getAttribute('app');
 
+        // Admins bypass all permission checks
+        if ($user && $this->registry->isAdmin(['user' => $user])) {
+            return $handler->handle($request);
+        }
+
         // Check app-level read permission if PermissionService is available
         if ($this->permissionService !== null && $app) {
             if ($this->permissionService->exists($app)) {
-                // Pass empty string for guests — backend returns guest permissions
                 $checkUser = $user ?: '';
                 if (!$this->permissionService->hasPermission($app, $checkUser, ['read'])) {
                     return $this->redirectToLogin($request);
                 }
-                // Permission granted — allow through even if not authenticated (guest read)
                 return $handler->handle($request);
             }
         }
diff --git a/src/Prefs/DateFormatPrefs.php b/src/Prefs/DateFormatPrefs.php
new file mode 100644
index 00000000..00330464
--- /dev/null
+++ b/src/Prefs/DateFormatPrefs.php
@@ -0,0 +1,119 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright 2026 The Horde Project (http://www.horde.org/)
+ *
+ * See the enclosed file LICENSE for license information (LGPL). If you
+ * did not receive this file, see http://www.horde.org/licenses/lgpl21.
+ *
+ * @category  Horde
+ * @copyright 2026 The Horde Project
+ * @license   http://www.horde.org/licenses/lgpl21 LGPL 2.1
+ * @package   Core
+ */
+
+namespace Horde\Core\Prefs;
+
+use Horde\Date\Format;
+use Horde_Prefs;
+use Psr\Log\LoggerInterface;
+use Throwable;
+
+/**
+ * Date format preferences decorator
+ *
+ * Wraps date format preference access with automatic strftime-to-ICU
+ * conversion. On first access of a legacy strftime value:
+ * 1. Detects strftime format
+ * 2. Logs the conversion
+ * 3. Converts to ICU pattern
+ * 4. Writes back the converted value (failsafe, noop if impossible)
+ * 5. Returns the ICU pattern
+ *
+ * @category  Horde
+ * @copyright 2026 The Horde Project
+ * @license   http://www.horde.org/licenses/lgpl21 LGPL 2.1
+ * @package   Core
+ */
+class DateFormatPrefs
+{
+    private const DATE_FORMAT_KEYS = [
+        'date_format',
+        'date_format_mini',
+        'time_format',
+        'time_format_mini',
+    ];
+
+    public function __construct(
+        private Horde_Prefs $prefs,
+        private string $locale = 'en_US',
+        private ?LoggerInterface $logger = null,
+    ) {}
+
+    /**
+     * Get a date format preference as an ICU pattern.
+     *
+     * If the stored value is strftime, converts it to ICU, writes back
+     * the converted value (failsafe), logs the conversion, and returns
+     * the ICU pattern. If already ICU, returns as-is.
+     */
+    public function getDateFormat(string $key): string
+    {
+        $value = $this->prefs->getValue($key);
+        if ($value === null) {
+            return '';
+        }
+
+        if (!Format::isStrftimeFormat($value)) {
+            return $value;
+        }
+
+        $icu = Format::strftimeToIcu($value, $this->locale);
+
+        $this->logger?->notice(
+            "DateFormatPrefs: converting legacy strftime pref '{$key}': '{$value}' → '{$icu}'"
+        );
+
+        if (!$this->prefs->isLocked($key)) {
+            try {
+                $this->prefs->setValue($key, $icu);
+            } catch (Throwable) {
+                // Noop — read-only backend or other error
+            }
+        }
+
+        return $icu;
+    }
+
+    /**
+     * Get the short time format ICU pattern based on twentyFour pref.
+     *
+     * Replaces the common pattern:
+     *   $prefs->getValue('twentyFour') ? '%R' : '%I:%M%p'
+     */
+    public function getTimeFormatShort(): string
+    {
+        return $this->prefs->getValue('twentyFour') ? 'HH:mm' : 'h:mm a';
+    }
+
+    /**
+     * Get the time format with seconds based on twentyFour pref.
+     *
+     * Replaces the common pattern:
+     *   $prefs->getValue('twentyFour') ? '%H:%M:%S' : '%I:%M:%S %p'
+     */
+    public function getTimeFormatFull(): string
+    {
+        return $this->prefs->getValue('twentyFour') ? 'HH:mm:ss' : 'h:mm:ss a';
+    }
+
+    /**
+     * Check if a given pref key is a date format key handled by this class.
+     */
+    public function isDateFormatKey(string $key): bool
+    {
+        return in_array($key, self::DATE_FORMAT_KEYS, true);
+    }
+}
diff --git a/src/Prefs/StrftimeFinding.php b/src/Prefs/StrftimeFinding.php
index fce104ea..4b16cecd 100644
--- a/src/Prefs/StrftimeFinding.php
+++ b/src/Prefs/StrftimeFinding.php
@@ -52,7 +52,7 @@ public function __construct(
         public readonly string $field,
         public readonly string $location,
         public readonly string $strftime,
-        public readonly string|array $icu,
+        public readonly string $icu,
         public readonly string $confidence,
     ) {
         if (!in_array($confidence, [self::CONFIDENCE_HIGH, self::CONFIDENCE_MEDIUM, self::CONFIDENCE_LOW], true)) {
@@ -60,29 +60,13 @@ public function __construct(
         }
     }
 
-    /**
-     * Check if ICU pattern is locale-specific
-     *
-     * @return bool True if pattern depends on user locale
-     */
-    public function isLocaleSpecific(): bool
-    {
-        return is_array($this->icu);
-    }
-
     /**
      * Get ICU pattern as string
      *
-     * For locale-specific patterns, returns a description.
-     * For concrete patterns, returns the pattern itself.
-     *
-     * @return string ICU pattern or description
+     * @return string ICU pattern
      */
     public function getIcuString(): string
     {
-        if (is_array($this->icu)) {
-            return '[locale-specific: ' . implode(', ', array_keys($this->icu)) . ']';
-        }
         return $this->icu;
     }