feat(together): cursor-based pagination API — limit/cursor クエリパラメーター追加

server.js

@@ -2547,8 +2547,17 @@ ${excerpt}
     });
 
     // GET /together/feed/:groupId — フィード（リアクション・コメント数付き）
+    // ?limit=N&cursor=<ISO timestamp> でカーソルページネーション対応
     r.get('/together/feed/:groupId', async (req, res) => {
         try {
+            const limit  = Math.min(parseInt(req.query.limit) || 20, 50);
+            const cursor = req.query.cursor; // shared_at の ISO タイムスタンプ
+            const params = [req.params.groupId];
+            let cursorClause = '';
+            if (cursor) {
+                params.push(cursor);
+                cursorClause = 'AND s.shared_at < $2';
+            }
             const result = await pool.query(`
                 SELECT
                     s.*,
@@ -2560,12 +2569,16 @@ ${excerpt}
                 FROM together_shares s
                 LEFT JOIN together_reactions r ON r.share_id = s.id
                 LEFT JOIN together_comments c ON c.share_id = s.id
-                WHERE s.group_id = $1
+                WHERE s.group_id = $1 ${cursorClause}
                 GROUP BY s.id
                 ORDER BY s.shared_at DESC
-                LIMIT 50
-            `, [req.params.groupId]);
-            res.json(result.rows);
+                LIMIT ${limit + 1}
+            `, params);
+            const rows    = result.rows;
+            const hasMore = rows.length > limit;
+            const items   = hasMore ? rows.slice(0, limit) : rows;
+            const nextCursor = items.length > 0 ? items[items.length - 1].shared_at : null;
+            res.json({ items, next_cursor: nextCursor, has_more: hasMore });
         } catch (e) {
             console.error('[together/feed]', e.message);
             res.status(500).json({ error: 'Internal server error' });