diff --git a/par-core/src/main/java/com/par/core/mapper/SiteSnapshotMapper.java b/par-core/src/main/java/com/par/core/mapper/SiteSnapshotMapper.java
index aa4e1da..883e434 100644
--- a/par-core/src/main/java/com/par/core/mapper/SiteSnapshotMapper.java
+++ b/par-core/src/main/java/com/par/core/mapper/SiteSnapshotMapper.java
@@ -19,4 +19,8 @@ public interface SiteSnapshotMapper extends BaseMapper<SiteSnapshot> {
     /** 查询站点最新的 published 快照 */
     @Select("SELECT * FROM site_snapshots WHERE site_id = #{siteId} AND status = 'published' ORDER BY version DESC LIMIT 1")
     SiteSnapshot selectLatestPublished(@Param("siteId") String siteId);
+
+    /** 查询站点最新快照：draft 优先，无 draft 则取 published */
+    @Select("SELECT * FROM site_snapshots WHERE site_id = #{siteId} AND status IN ('draft','published') ORDER BY CASE WHEN status = 'draft' THEN 0 ELSE 1 END, version DESC LIMIT 1")
+    SiteSnapshot selectLatestWithDraft(@Param("siteId") String siteId);
 }
diff --git a/par-core/src/main/java/com/par/core/service/impl/SiteSnapshotServiceImpl.java b/par-core/src/main/java/com/par/core/service/impl/SiteSnapshotServiceImpl.java
index 2f726f2..b5ce314 100644
--- a/par-core/src/main/java/com/par/core/service/impl/SiteSnapshotServiceImpl.java
+++ b/par-core/src/main/java/com/par/core/service/impl/SiteSnapshotServiceImpl.java
@@ -55,6 +55,12 @@ public class SiteSnapshotServiceImpl implements SiteSnapshotService {
             .maximumSize(500)
             .build();
 
+    /** preview 快照 JSON 缓存：draft 优先 fallback published */
+    private final Cache<String, String> previewJsonCache = Caffeine.newBuilder()
+            .expireAfterWrite(Duration.ofMinutes(5))
+            .maximumSize(500)
+            .build();
+
     @Override
     public Map<String, Object> buildSnapshot(String siteId) {
         Map<String, Object> snapshot = new LinkedHashMap<>();
@@ -243,8 +249,9 @@ public class SiteSnapshotServiceImpl implements SiteSnapshotService {
         // 序列化并刷新缓存
         String bundleJson = toBundleJson(draft);
         bundleJsonCache.put(siteId, bundleJson);
-        // 发布后 draft 缓存已过时，清除
+        // 发布后 draft/preview 缓存已过时
         draftJsonCache.invalidate(siteId);
+        previewJsonCache.invalidate(siteId);
 
         // 上传到七牛云 CDN 作为灾备（复用已序列化的 JSON）
         try {
@@ -297,12 +304,16 @@ public class SiteSnapshotServiceImpl implements SiteSnapshotService {
 
     @Override
     public String getPreviewBundleJson(String siteId) {
-        // 先查 draft，有则返回；无则 fallback 到 published
-        String draftJson = getDraftBundleJson(siteId);
-        if (draftJson != null && !draftJson.isEmpty()) {
-            return draftJson;
-        }
-        return getActiveBundleJson(siteId);
+        // draft 优先，无 draft 则取 published — 一次查询
+        return previewJsonCache.get(siteId, key -> {
+            SiteSnapshot snapshot = snapshotMapper.selectLatestWithDraft(key);
+            if (snapshot == null) {
+                log.debug("站点 {} 无任何快照", key);
+                return "";
+            }
+            log.debug("预览缓存未命中 siteId={} status={}", key, snapshot.getStatus());
+            return toBundleJson(snapshot);
+        });
     }
 
     @Override