rebuild(stage-7): deliver ladder and sector rotation

next/backend/data/repository.py

@@ -188,6 +188,52 @@ class MarketRepository:
             (through,),
         ).fetchone()
 
+    def sector_members(
+        self, connection: sqlite3.Connection, trade_date: str, sector_name: str
+    ) -> sqlite3.Row | None:
+        return connection.execute(
+            """
+            SELECT * FROM sector_member_snapshots
+            WHERE trade_date = ? AND sector_name = ?
+            """,
+            (trade_date, sector_name),
+        ).fetchone()
+
+    def save_sector_members(
+        self,
+        connection: sqlite3.Connection,
+        *,
+        trade_date: str,
+        sector_name: str,
+        sector_code: str,
+        observed_at: str,
+        source: str,
+        coverage: float,
+        payload: dict[str, Any],
+    ) -> None:
+        connection.execute(
+            """
+            INSERT INTO sector_member_snapshots (
+                trade_date, sector_name, sector_code, observed_at, source, coverage, payload_json
+            ) VALUES (?, ?, ?, ?, ?, ?, ?)
+            ON CONFLICT(trade_date, sector_name) DO UPDATE SET
+                sector_code = excluded.sector_code,
+                observed_at = excluded.observed_at,
+                source = excluded.source,
+                coverage = excluded.coverage,
+                payload_json = excluded.payload_json
+            """,
+            (
+                trade_date,
+                sector_name,
+                sector_code,
+                observed_at,
+                source,
+                coverage,
+                json.dumps(payload, ensure_ascii=False, separators=(",", ":")),
+            ),
+        )
+
     def save_chart(
         self,
         connection: sqlite3.Connection,