feat(HEL-421): 回补历史日历和指数并标记区间不完整

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

backend/data/datahub/bridge.py

@@ -208,6 +208,10 @@ class DatahubBridge:
             raise DatahubError("STALE", f"{dataset} data is stale")
         if dataset in EMPTY_FAIL_DATASETS and not rows:
             raise DatahubError("EMPTY", f"{dataset} returned no rows")
+        coverage = meta.get("coverage") if isinstance(meta.get("coverage"), dict) else {}
+        if meta.get("incomplete") is True or coverage.get("complete") is False:
+            missing = coverage.get("missing_count")
+            raise DatahubError("INCOMPLETE", f"{dataset} range is incomplete missing={missing}")
 
     def _require_fresh(self, response: DatahubResponse, dataset: str) -> DatahubResponse:
         self._validate_usable(dataset, list(response.data or []) if isinstance(response.data, list) else [], response)