Fix: don't update last_sync when partitioned sync gets 0 new rows

When BQ returns empty results (e.g., data not yet refreshed), the
scheduler was marking sync as complete for the day. This meant the
next 15-min tick would skip it ("none are due") and data would stay
stale until the next day's scheduled run.

Now: if partitioned sync processes partitions but gets 0 new rows,
last_sync is NOT updated. The scheduler will retry on the next tick
(15 min later) when data may be available.

connectors/bigquery/adapter.py

@@ -104,7 +104,20 @@ class BigQueryDataSource(DataSource):
             else:
                 raise ValueError(f"Unknown sync strategy: {table_config.sync_strategy}")
 
-            # Update sync state
+            # Skip sync state update if partitioned sync got no new data.
+            # This lets the scheduler retry on the next tick instead of
+            # marking the sync as done for the day with stale data.
+            skip_state_update = (
+                table_config.sync_strategy == "partitioned"
+                and result.get("partitions_updated", -1) == 0
+            )
+
+            if skip_state_update:
+                logger.warning(
+                    f"Partitioned sync for {table_config.name} got 0 new partitions "
+                    f"- NOT updating last_sync (will retry next tick)"
+                )
+            else:
                 sync_state.update_sync(
                     table_id=table_config.id,
                     table_name=table_config.name,
@@ -412,7 +425,9 @@ class BigQueryDataSource(DataSource):
             f"{total_rows} total rows processed"
         )
 
-        return self._get_partition_totals(partition_dir)
+        result = self._get_partition_totals(partition_dir)
+        result["partitions_updated"] = partitions_updated
+        return result
 
     @staticmethod
     def _generate_partition_dates(