Tighten type hints in split_by_version() in backfill_history.py

Co-authored-by: jordanpadams <33492486+jordanpadams@users.noreply.github.com>
Agent-Logs-Url: https://github.com/NASA-PDS/registry/sessions/ab42f1c3-5d84-40a5-b8c0-c00a2938c827

Author: Copilot

scripts/backfill_history.py

@@ -47,9 +47,9 @@
 
 # ── version splitting (mirrors generate_registry_status_reports.py) ──────────
 
-def split_by_version(rows: list[list[str]]) -> tuple[list, list]:
+def split_by_version(rows: list[list[str]]) -> tuple[list[list[str]], list[list[str]]]:
     """Split rows into (latest, superseded) by LID using numeric version comparison."""
-    by_lid: dict[str, list] = defaultdict(list)
+    by_lid: dict[str, list[tuple[tuple[int, ...], list[str]]]] = defaultdict(list)
     for row in rows:
         lidvid = row[1] if len(row) > 1 else ""
         if "::" in lidvid:
@@ -62,7 +62,8 @@ def split_by_version(rows: list[list[str]]) -> tuple[list, list]:
             ver_key = (0,)
         by_lid[lid].append((ver_key, row))
 
-    latest, superseded = [], []
+    latest: list[list[str]] = []
+    superseded: list[list[str]] = []
     for version_rows in by_lid.values():
         sorted_rows = sorted(version_rows, key=lambda x: x[0], reverse=True)
         latest.append(sorted_rows[0][1])