fix: focus failure-report agent scope

tests/test_agent.py

@@ -22,6 +22,8 @@ def test_task_uses_issue_text_not_github_parser() -> None:
 
 def test_system_prompt_requires_precise_diff_hygiene() -> None:
     assert "Never create backup files" in _SYSTEM_TEMPLATE
+    assert "failure-report transport code" in _SYSTEM_TEMPLATE
     assert "Preserve unrelated lines exactly" in _SYSTEM_TEMPLATE
+    assert "closest existing test class" in _SYSTEM_TEMPLATE
     assert "inspect all key columns and cardinality" in _SYSTEM_TEMPLATE
     assert "remove trailing spaces" in _SYSTEM_TEMPLATE