diff --git a/server.js b/server.js
index 380abc0d..289fa3d3 100644
--- a/server.js
+++ b/server.js
@@ -2632,9 +2632,17 @@ ${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
             await pool.query(
-                `UPDATE together_shares SET full_content=$1, title=COALESCE(title, $2) WHERE id=$3`,
-                [fullContent, jinaTitle, shareId]
+                `UPDATE together_shares
+                 SET full_content=$1,
+                     title=CASE
+                       WHEN title IS NULL THEN $2
+                       WHEN $2 IS NOT NULL AND title = (regexp_replace($3, '^https?://(www\.)?', ''))::text THEN $2
+                       ELSE title
+                     END
+                 WHERE id=$4`,
+                [fullContent, jinaTitle, url, shareId]
             );
 
             function parseGeminiJson(raw) {