Avoid full task hydration for Jira relation lookup (JVNAUTOSCI-2737)

src/backend/services/jira_task_import_service.py

@@ -1672,6 +1672,7 @@ def _resolve_existing_task_id(
         source_system=_JIRA_SOURCE_SYSTEM,
         external_id=jira_issue_key,
         organisation_concept_id=organisation_concept_id,
+        include_details=False,
     )
     task_id = None
     if isinstance(existing_task, Mapping):

src/backend/services/task_management_service.py

@@ -5435,7 +5435,9 @@ def find_task_by_external_reference(
     source_system: str,
     external_id: str,
     organisation_concept_id: str | None = None,
+    include_details: bool = True,
 ) -> Dict[str, Any] | None:
+    """Resolve the same visible task with optional response construction."""
     source_key = _normalise_external_reference_source_system(source_system)
     external_value = _normalise_external_reference_id(external_id)
 
@@ -5451,6 +5453,11 @@ def find_task_by_external_reference(
         ],
     }
     doc: Dict[str, Any] | None = None
+    lookup_options = (
+        {}
+        if include_details
+        else {"projection": {"concept_id": 1, "relationships.is_an_instance_of": 1}}
+    )
     if organisation_concept_id:
         org_id = _normalise_optional_concept_id(organisation_concept_id)
         if not org_id:
@@ -5459,18 +5466,20 @@ def find_task_by_external_reference(
             )
         scoped_query = dict(query_base)
         scoped_query[f"metadata.{TASK_METADATA_KEY_ORGANISATION}"] = org_id
-        doc = ConceptsRepository.find_one(scoped_query)
+        doc = ConceptsRepository.find_one(scoped_query, **lookup_options)
         if not isinstance(doc, dict) or not _is_task_doc(doc):
             # Legacy imports were often unscoped; allow a constrained fallback
             # to null/absent organisation scope for idempotent repair runs.
             legacy_query = dict(query_base)
             legacy_query[f"metadata.{TASK_METADATA_KEY_ORGANISATION}"] = None
-            doc = ConceptsRepository.find_one(legacy_query)
+            doc = ConceptsRepository.find_one(legacy_query, **lookup_options)
     else:
-        doc = ConceptsRepository.find_one(query_base)
+        doc = ConceptsRepository.find_one(query_base, **lookup_options)
 
     if not isinstance(doc, dict) or not _is_task_doc(doc):
         return None
+    if not include_details:
+        return {"task_concept_id": doc.get("concept_id")}
     return _build_task_response(doc)
 
 

tests/backend/test_task_management_service.py

@@ -2100,6 +2100,50 @@ def _fake_get_texts(
 
 
 class TestTaskExternalReferences:
+    @patch("src.backend.services.task_management_service._build_task_response")
+    @patch("src.backend.services.task_management_service.ConceptsRepository")
+    def test_identity_lookup_preserves_alias_and_legacy_scope_without_hydration(
+        self, mock_repo: MagicMock, build_response: MagicMock
+    ) -> None:
+        mock_repo.find_one.side_effect = [
+            None,
+            {
+                "concept_id": "#V#legacy_task",
+                "relationships": {"is_an_instance_of": [TASK_SPECIFICATION_TYPE_ID]},
+            },
+        ]
+        result = find_task_by_external_reference(
+            source_system="jira",
+            external_id="OLD-1",
+            organisation_concept_id="#V#org",
+            include_details=False,
+        )
+        assert result == {"task_concept_id": "#V#legacy_task"}
+        build_response.assert_not_called()
+        calls = mock_repo.find_one.call_args_list
+        assert [call.args[0]["metadata.organisation_concept_id"] for call in calls] == [
+            "#V#org", None
+        ]
+        for call in calls:
+            assert {"metadata.external_references.jira.previous_issue_keys": "OLD-1"} in (
+                call.args[0]["$or"]
+            )
+            assert call.kwargs["projection"] == {
+                "concept_id": 1, "relationships.is_an_instance_of": 1
+            }
+
+    @pytest.mark.parametrize("doc", [None, {"concept_id": "#V#not_a_task"}])
+    @patch("src.backend.services.task_management_service._build_task_response")
+    @patch("src.backend.services.task_management_service.ConceptsRepository")
+    def test_identity_lookup_does_not_return_missing_or_non_task_records(
+        self, mock_repo: MagicMock, build_response: MagicMock, doc
+    ) -> None:
+        mock_repo.find_one.return_value = doc
+        assert find_task_by_external_reference(
+            source_system="jira", external_id="PROJ-1", include_details=False
+        ) is None
+        build_response.assert_not_called()
+
     @patch("src.backend.services.task_management_service.ConceptsRepository")
     @patch("src.backend.services.task_management_service.get_texts_for_concept")
     def test_find_task_by_external_reference_returns_task(