BatchLoader: re-raise exceptions stored as results

ingestify/domain/models/resources/batch_loader.py

@@ -18,6 +18,11 @@ def load(file_resources, current_files, dataset_resources):
 
 current_files may contain None entries (for create tasks) or a File (for
 update tasks) — the loader_fn handles both.
+
+Error propagation: if the loader_fn stores an Exception instead of a
+DraftFile for a specific item, __call__ will re-raise it when that item's
+task runs. This lets successful items in a batch proceed while failed items
+cause their individual tasks to fail and be retried on the next run.
 """
 from typing import Callable, List
 
@@ -35,7 +40,10 @@ def __call__(self, file_resource, current_file, dataset_resource=None, **kwargs)
                 "BatchLoader result not precomputed. A BatchTask must "
                 "populate the cache before inner tasks execute."
             )
-        return self._results.pop(key)
+        result = self._results.pop(key)
+        if isinstance(result, BaseException):
+            raise result
+        return result
 
     def _store_results(self, file_resources: List, results: List):
         """Store batch results so they can be retrieved via __call__."""

ingestify/tests/test_batch_loader.py

@@ -21,3 +21,19 @@ def test_batch_loader_raises_if_not_precomputed():
 
     with pytest.raises(RuntimeError, match="not precomputed"):
         batch_loader(object(), current_file=None)
+
+
+def test_batch_loader_propagates_stored_exception():
+    """When an Exception is stored as a result, __call__ re-raises it."""
+    batch_loader = BatchLoader(lambda frs, cfs, drs: [], batch_size=5)
+    fr_ok, fr_err = object(), object()
+
+    original_error = ValueError("Google Ads daily quota exhausted")
+    batch_loader._store_results([fr_ok, fr_err], ["good_result", original_error])
+
+    # Good result works normally
+    assert batch_loader(fr_ok, current_file=None) == "good_result"
+
+    # Error result re-raises the original exception
+    with pytest.raises(ValueError, match="daily quota exhausted"):
+        batch_loader(fr_err, current_file=None)