Empty YAML section keys in CLI config handling

Fixes on record

Merged to main. A stamp counts the issues a fix is linked to.

• #61733 fix(config): empty YAML section keys no longer replace default dicts (#58277)

  merged to main

  files: cli.py, hermes_cli/config.py, tests/hermes_cli/test_config.py, tests/hermes_cli/test_config_env_expansion.py

  Show the diff

  • cli.py

    @@ -543,6 +543,8 @@ def load_cli_config() -> Dict[str, Any]:
                     if key == "model":
                         continue  # Already handled above
                     if key in file_config:
    +                    if isinstance(defaults[key], dict) and file_config[key] is None:
    +                        continue
                         if isinstance(defaults[key], dict) and isinstance(file_config[key], dict):
                             defaults[key].update(file_config[key])
                         else:

  • hermes_cli/config.py

    @@ -6243,6 +6243,12 @@ def _deep_merge(base: dict, override: dict) -> dict:
         Keys in *override* take precedence. If both values are dicts the merge
         recurses, so a user who overrides only ``tts.elevenlabs.voice_id`` will
         keep the default ``tts.elevenlabs.model_id`` intact.
    +
    +    An empty section key in config.yaml (``terminal:`` with no value) parses
    +    as YAML ``None``; treating that as an override would replace the entire
    +    default dict with ``None`` and crash every downstream consumer that
    +    expects a mapping (#58277). A ``None`` override of a dict default is
    +    ignored — same as the key being absent.
         """
         result = base.copy()
         for key, value in override.items():
    @@ -6252,6 +6258,8 @@ def _deep_merge(base: dict, override: dict) -> dict:
                 and isinstance(value, dict)
             ):
                 result[key] = _deep_merge(result[key], value)
    +        elif key in result and isinstance(result[key], dict) and value is None:
    +            continue
             else:
                 result[key] = value
         return result

  • tests/hermes_cli/test_config.py

    @@ -360,6 +360,34 @@ def test_last_known_good_cached_no_rewarn_spam(self, tmp_path, capsys):
                 assert capsys.readouterr().err == ""
     
     
    +class TestEmptyConfigSections:
    +    """Empty section keys (``terminal:`` with no value) parse as YAML None
    +    and must not replace the default dict for that section (#58277)."""
    +
    +    def test_null_section_keeps_defaults_in_load_config(self, tmp_path):
    +        with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
    +            (tmp_path / "config.yaml").write_text(
    +                "model:\n  default: test/custom\n"
    +                "terminal:\n"
    +                "display:\n"
    +            )
    +            config = load_config()
    +            assert config["model"]["default"] == "test/custom"
    +            assert isinstance(config["terminal"], dict)
    +            assert config["terminal"] == DEFAULT_CONFIG["terminal"]
    +            assert isinstance(config["display"], dict)
    +
    +    def test_null_override_of_non_dict_default_still_applies(self, tmp_path):
    +        """None only shields dict defaults — explicit null for a scalar
    +        key remains an override (unchanged behavior)."""
    +        from hermes_cli.config import _deep_merge
    +
    +        merged = _deep_merge({"scalar": 5, "section": {"a": 1}},
    +                             {"scalar": None, "section": None})
    +        assert merged["scalar"] is None
    +        assert merged["section"] == {"a": 1}
    +
    +
     class TestSaveAndLoadRoundtrip:
         @staticmethod
         def _deny_config_reads(config_path):

  • tests/hermes_cli/test_config_env_expansion.py

    @@ -150,6 +150,18 @@ def test_unchanged_env_still_serves_cache(self, tmp_path, monkeypatch):
     class TestLoadCliConfigExpansion:
         """Verify that load_cli_config() also expands ${VAR} references."""
     
    +    def test_cli_config_ignores_empty_terminal_section(self, tmp_path, monkeypatch):
    +        config_file = tmp_path / "config.yaml"
    +        config_file.write_text("terminal:\n")
    +
    +        monkeypatch.setattr("cli._hermes_home", tmp_path)
    +
    +        from cli import load_cli_config
    +        config = load_cli_config()
    +
    +        assert isinstance(config["terminal"], dict)
    +        assert config["terminal"]["env_type"] == "local"
    +
         def test_cli_config_expands_auxiliary_api_key(self, tmp_path, monkeypatch):
             config_yaml = (
                 "auxiliary:\n"