refactor(harness): route workflow persistence through repositories

harness/tht/ctetest.py

@@ -99,7 +99,10 @@ def load_cte_tests(session_dir: Path) -> list[CteTestRecord]:
     path = session_dir / CTE_TESTS_FILE
     if not path.exists():
         return []
-    text = path.read_text()
+    return load_cte_tests_text(path.read_text())
+
+
+def load_cte_tests_text(text: str) -> list[CteTestRecord]:
     try:
         objs = list(_iter_json_objects(text))
     except json.JSONDecodeError as e:
@@ -107,6 +110,11 @@ def load_cte_tests(session_dir: Path) -> list[CteTestRecord]:
     return [CteTestRecord.model_validate(o) for o in objs]
 
 
+def append_cte_test_snapshot(repository, snapshot, record: CteTestRecord) -> None:
+    previous = snapshot.artifacts.get("cte_tests", "")
+    repository.write_artifact(snapshot.manifest.id, "cte_tests", previous + record.model_dump_json() + "\n")
+
+
 def append_cte_test(session_dir: Path, record: CteTestRecord) -> None:
     """Append atomico (una riga JSON per esito): scritture concorrenti sulla
     stessa sessione non si sovrascrivono, a differenza del rewrite dell'array."""