feat: add safe distributed checkpoint intake and preflight

tests/test_quant_dequant.py

@@ -215,6 +215,20 @@ def test_load_json_local_missing_returns_none(tmp_path):
     assert qd._load_json_from_checkpoint(str(tmp_path), "missing.json") is None
 
 
+def test_load_json_remote_unexpected_download_failure_returns_none(monkeypatch):
+    def fail_download(*args, **kwargs):
+        raise OSError("offline")
+
+    monkeypatch.setattr("huggingface_hub.hf_hub_download", fail_download)
+
+    assert qd._load_json_from_checkpoint(
+        "org/model",
+        "config.json",
+        revision="immutable-sha",
+        local_files_only=True,
+    ) is None
+
+
 def test_safetensors_key_names_reads_single_file_and_index(tmp_path):
     from safetensors.torch import save_file