diff --git a/README.md b/README.md
index b57099d..25691ef 100644
--- a/README.md
+++ b/README.md
@@ -149,6 +149,7 @@ BRANCH=master bash scripts/deploy.sh
 - плоские комментарии к фото,
 - удаление комментариев админом,
 - watermark на выдаче версии "после".
+- превью каталога (`thumbs/`) генерируются при загрузке/замене файла и после поворота.
 
 
 Админка использует тот же `token`, что и `deploy.php`, из файла `deploy-config.php`.
@@ -200,6 +201,7 @@ https://<домен>/deploy.php?token=<твой_секрет>
 ## Примечания
 
 - Превью генерируются в формате JPEG с качеством ~82.
+- Для разового backfill превью можно запустить: `php scripts/generate_thumbs.php`.
 - При первом заходе на большую папку возможно небольшое ожидание (генерация превью).
 - CSS/JS и favicon подключаются с cache-busting параметром `?v=<filemtime>`, чтобы после деплоя пользователю не приходилось чистить кеш вручную.
 - В футере публичной страницы есть ненавязчивое авторство со ссылкой: `https://t.me/andr33vru`.
diff --git a/admin.php b/admin.php
index d21deee..79bdff4 100644
--- a/admin.php
+++ b/admin.php
@@ -3,6 +3,7 @@
 declare(strict_types=1);
 
 require_once __DIR__ . '/lib/db_gallery.php';
+require_once __DIR__ . '/lib/thumbs.php';
 
 const MAX_UPLOAD_BYTES = 3 * 1024 * 1024;
 
@@ -171,8 +172,17 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
             if (isset($_FILES['after']) && (int)($_FILES['after']['error'] ?? UPLOAD_ERR_NO_FILE) !== UPLOAD_ERR_NO_FILE) {
                 $p = photoById($photoId);
                 if (!$p) throw new RuntimeException('Фото не найдено');
+                $oldAfterPath = (string)($p['after_path'] ?? '');
                 $up = saveSingleImage($_FILES['after'], $code . 'р', (int)$p['section_id']);
                 photoFileUpsert($photoId, 'after', $up['path'], $up['mime'], $up['size']);
+
+                if ($oldAfterPath !== '' && $oldAfterPath !== $up['path']) {
+                    deleteThumbBySourcePath(__DIR__, $oldAfterPath);
+                    $oldAbs = __DIR__ . '/' . ltrim($oldAfterPath, '/');
+                    if (is_file($oldAbs)) {
+                        @unlink($oldAbs);
+                    }
+                }
             }
 
             $message = 'Фото обновлено';
@@ -196,6 +206,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
             photoFileUpsert($photoId, 'after', $up['path'], $up['mime'], $up['size']);
 
             if ($oldAfterPath !== '' && $oldAfterPath !== $up['path']) {
+                deleteThumbBySourcePath(__DIR__, $oldAfterPath);
                 $oldAbs = __DIR__ . '/' . ltrim($oldAfterPath, '/');
                 if (is_file($oldAbs)) {
                     @unlink($oldAbs);
@@ -266,6 +277,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
                 if ($p) {
                     foreach (['before_path', 'after_path'] as $k) {
                         if (!empty($p[$k])) {
+                            deleteThumbBySourcePath(__DIR__, (string)$p[$k]);
                             $abs = __DIR__ . '/' . ltrim((string)$p[$k], '/');
                             if (is_file($abs)) @unlink($abs);
                         }
@@ -296,6 +308,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
 
             $degrees = $direction === 'left' ? -90 : 90;
             rotateImageOnDisk($absPath, $degrees);
+            ensureThumbForSource(__DIR__, $relPath);
 
             $st = db()->prepare('UPDATE photo_files SET updated_at=CURRENT_TIMESTAMP WHERE photo_id=:pid AND kind=:kind');
             $st->execute(['pid' => $photoId, 'kind' => $kind]);
@@ -541,8 +554,11 @@ function saveSingleImage(array $file, string $baseName, int $sectionId): array
 
     if (!move_uploaded_file($tmp, $dest)) throw new RuntimeException('Не удалось сохранить файл');
 
+    $storedRelPath = 'photos/section_' . $sectionId . '/' . $name;
+    ensureThumbForSource(__DIR__, $storedRelPath);
+
     return [
-        'path' => 'photos/section_' . $sectionId . '/' . $name,
+        'path' => $storedRelPath,
         'mime' => $mime,
         'size' => $size,
     ];
@@ -613,6 +629,7 @@ function removeSectionImageFiles(int $sectionId): void
         if (is_file($abs)) {
             @unlink($abs);
         }
+        deleteThumbBySourcePath(__DIR__, $path);
     }
 }
 
diff --git a/lib/thumbs.php b/lib/thumbs.php
new file mode 100644
index 0000000..4320e04
--- /dev/null
+++ b/lib/thumbs.php
@@ -0,0 +1,131 @@
+<?php
+
+declare(strict_types=1);
+
+function thumbRelativePathForSource(string $sourceRelPath): string
+{
+    $normalized = ltrim(str_replace('\\', '/', $sourceRelPath), '/');
+    $hash = sha1($normalized);
+    $base = (string)pathinfo($normalized, PATHINFO_FILENAME);
+    $safeBase = preg_replace('/[^A-Za-z0-9._-]+/', '_', $base) ?? 'photo';
+    $safeBase = trim($safeBase, '._-');
+    if ($safeBase === '') {
+        $safeBase = 'photo';
+    }
+
+    return 'thumbs/' . substr($hash, 0, 2) . '/' . substr($hash, 2, 2) . '/' . $safeBase . '_' . $hash . '.jpg';
+}
+
+function thumbAbsolutePathForSource(string $projectRoot, string $sourceRelPath): string
+{
+    return rtrim($projectRoot, '/') . '/' . ltrim(thumbRelativePathForSource($sourceRelPath), '/');
+}
+
+function ensureThumbForSource(string $projectRoot, string $sourceRelPath, int $maxWidth = 520, int $maxHeight = 360, int $quality = 82): ?string
+{
+    $normalized = ltrim(str_replace('\\', '/', $sourceRelPath), '/');
+    if ($normalized === '') {
+        return null;
+    }
+
+    $sourceAbs = rtrim($projectRoot, '/') . '/' . $normalized;
+    if (!is_file($sourceAbs)) {
+        return null;
+    }
+
+    $thumbRel = thumbRelativePathForSource($normalized);
+    $thumbAbs = rtrim($projectRoot, '/') . '/' . ltrim($thumbRel, '/');
+    $srcMtime = (int)(filemtime($sourceAbs) ?: 0);
+    $thumbMtime = (int)(filemtime($thumbAbs) ?: 0);
+    if ($thumbMtime > 0 && $thumbMtime >= $srcMtime) {
+        return $thumbRel;
+    }
+
+    $dir = dirname($thumbAbs);
+    if (!is_dir($dir) && !mkdir($dir, 0775, true) && !is_dir($dir)) {
+        return null;
+    }
+
+    if (extension_loaded('imagick') && createThumbWithImagick($sourceAbs, $thumbAbs, $maxWidth, $maxHeight, $quality)) {
+        return $thumbRel;
+    }
+    if (createThumbWithGd($sourceAbs, $thumbAbs, $maxWidth, $maxHeight, $quality)) {
+        return $thumbRel;
+    }
+
+    return null;
+}
+
+function deleteThumbBySourcePath(string $projectRoot, string $sourceRelPath): void
+{
+    $normalized = ltrim(str_replace('\\', '/', $sourceRelPath), '/');
+    if ($normalized === '') {
+        return;
+    }
+
+    $abs = thumbAbsolutePathForSource($projectRoot, $normalized);
+    if (is_file($abs)) {
+        @unlink($abs);
+    }
+}
+
+function createThumbWithImagick(string $sourceAbs, string $thumbAbs, int $maxWidth, int $maxHeight, int $quality): bool
+{
+    try {
+        $img = new Imagick($sourceAbs);
+        if (method_exists($img, 'autoOrient')) {
+            $img->autoOrient();
+        } else {
+            $img->setImageOrientation(Imagick::ORIENTATION_TOPLEFT);
+        }
+        $img->thumbnailImage(max(1, $maxWidth), max(1, $maxHeight), true, true);
+        $img->setImageFormat('jpeg');
+        $img->setImageCompressionQuality(max(30, min(95, $quality)));
+        $img->stripImage();
+        $ok = $img->writeImage($thumbAbs);
+        $img->clear();
+        $img->destroy();
+        return (bool)$ok;
+    } catch (Throwable) {
+        return false;
+    }
+}
+
+function createThumbWithGd(string $sourceAbs, string $thumbAbs, int $maxWidth, int $maxHeight, int $quality): bool
+{
+    [$srcW, $srcH, $type] = @getimagesize($sourceAbs) ?: [0, 0, 0];
+    if ($srcW < 1 || $srcH < 1) {
+        return false;
+    }
+
+    $src = match ($type) {
+        IMAGETYPE_JPEG => @imagecreatefromjpeg($sourceAbs),
+        IMAGETYPE_PNG => @imagecreatefrompng($sourceAbs),
+        IMAGETYPE_GIF => @imagecreatefromgif($sourceAbs),
+        IMAGETYPE_WEBP => function_exists('imagecreatefromwebp') ? @imagecreatefromwebp($sourceAbs) : false,
+        default => false,
+    };
+    if (!$src) {
+        return false;
+    }
+
+    $scale = min($maxWidth / $srcW, $maxHeight / $srcH, 1);
+    $dstW = max(1, (int)round($srcW * $scale));
+    $dstH = max(1, (int)round($srcH * $scale));
+
+    $dst = imagecreatetruecolor($dstW, $dstH);
+    if ($dst === false) {
+        imagedestroy($src);
+        return false;
+    }
+
+    $bg = imagecolorallocate($dst, 255, 255, 255);
+    imagefill($dst, 0, 0, $bg);
+
+    $okCopy = imagecopyresampled($dst, $src, 0, 0, 0, 0, $dstW, $dstH, $srcW, $srcH);
+    $okSave = $okCopy && imagejpeg($dst, $thumbAbs, max(30, min(95, $quality)));
+
+    imagedestroy($src);
+    imagedestroy($dst);
+    return (bool)$okSave;
+}
diff --git a/scripts/generate_thumbs.php b/scripts/generate_thumbs.php
new file mode 100644
index 0000000..b9487d3
--- /dev/null
+++ b/scripts/generate_thumbs.php
@@ -0,0 +1,42 @@
+#!/usr/bin/env php
+<?php
+
+declare(strict_types=1);
+
+require __DIR__ . '/../lib/db.php';
+require __DIR__ . '/../lib/thumbs.php';
+
+try {
+    $pdo = db();
+} catch (Throwable $e) {
+    fwrite(STDERR, "DB connection failed: " . $e->getMessage() . PHP_EOL);
+    exit(1);
+}
+
+$st = $pdo->query('SELECT file_path FROM photo_files ORDER BY id');
+$paths = $st ? $st->fetchAll(PDO::FETCH_COLUMN) : [];
+if (!is_array($paths)) {
+    $paths = [];
+}
+
+$total = 0;
+$ok = 0;
+$missing = 0;
+
+foreach ($paths as $path) {
+    if (!is_string($path) || $path === '') {
+        continue;
+    }
+
+    $total++;
+    $thumb = ensureThumbForSource(dirname(__DIR__), $path);
+    if ($thumb !== null) {
+        $ok++;
+        continue;
+    }
+    $missing++;
+}
+
+echo "checked: {$total}" . PHP_EOL;
+echo "generated_or_fresh: {$ok}" . PHP_EOL;
+echo "missing_or_failed: {$missing}" . PHP_EOL;