fix(tools): guard csv replace against newer fan records

tools/import_fans_csv.py

@@ -149,12 +149,24 @@ def import_fans_series(
     mid: int = DEFAULT_MID,
     force: bool = False,
     replace: bool = False,
+    allow_lossy_replace: bool = False,
     dry_run: bool = False,
 ) -> dict[str, Any]:
     """把解析后的序列写入 ``up_stat``。"""
     points = list(series.get("points", []))
     repo = Repository(db)
     deleted = 0
+    last_csv = str(series.get("last_date") or "")
+    if replace and last_csv:
+        newer = db.read(lambda conn: int(conn.execute(
+            "SELECT COUNT(*) FROM up_stat WHERE mid = ? AND stat_date > ?",
+            (int(mid), last_csv),
+        ).fetchone()[0]))
+        if newer and not allow_lossy_replace:
+            raise ValueError(
+                f"数据库中存在 {newer} 条晚于 CSV 末尾 {last_csv} 的粉丝记录；"
+                "确认要用 CSV 覆盖并删除这些记录时请加 --allow-lossy-replace"
+            )
     if replace:
         if dry_run:
             deleted = db.read(lambda conn: int(conn.execute(
@@ -226,6 +238,10 @@ def main(argv: Sequence[str] | None = None) -> int:
         "--replace", action="store_true",
         help="先清空该 mid 的全部粉丝历史，再用 CSV 重建",
     )
+    parser.add_argument(
+        "--allow-lossy-replace", action="store_true",
+        help="配合 --replace：允许删除数据库中晚于 CSV 末尾的记录",
+    )
     parser.add_argument("--dry-run", action="store_true", help="只计算，不写数据库")
     args = parser.parse_args(list(argv) if argv is not None else None)
 
@@ -242,6 +258,7 @@ def main(argv: Sequence[str] | None = None) -> int:
                 mid=args.mid,
                 force=args.force,
                 replace=args.replace,
+                allow_lossy_replace=args.allow_lossy_replace,
                 dry_run=args.dry_run,
             )
         finally: