diff --git a/server.js b/server.js
index a2314a68..1b5a95eb 100644
--- a/server.js
+++ b/server.js
@@ -2632,17 +2632,16 @@ ${excerpt}
                 }
             } catch (_) {}
 
-            // x.com など既存タイトルがドメイン名のみの場合は Jina タイトルで上書き
+            // 既存タイトルがドメイン名のみの場合は Jina タイトルで上書き（JS 側で判定）
+            let hostname = '';
+            try { hostname = new URL(url).hostname.replace('www.', ''); } catch (_) {}
+            const titleOverwrite = jinaTitle && hostname && jinaTitle !== hostname;
             await pool.query(
                 `UPDATE together_shares
                  SET full_content=$1,
-                     title=CASE
-                       WHEN title IS NULL THEN $2::text
-                       WHEN $2::text IS NOT NULL AND title = regexp_replace($3::text, '^https?://(www\.)?([^/]+).*$', '\2') THEN $2::text
-                       ELSE title
-                     END
-                 WHERE id=$4`,
-                [fullContent, jinaTitle, url, shareId]
+                     title=CASE WHEN title IS NULL OR ($2::boolean AND title=$3::text) THEN $4::text ELSE title END
+                 WHERE id=$5`,
+                [fullContent, titleOverwrite, hostname, jinaTitle, shareId]
             );
 
             function parseGeminiJson(raw) {