fix(honcho): save_config refuses to rewrite a honcho.json that does not parse

hermes memory setup writes through HonchoMemoryProvider.save_config, which
merged the new values over {} when the existing file could not be parsed
and then replaced the file. same wipe as the oauth and cli write paths,
through a different door. it now reads through _read_config_strict and
raises, so the caller sees the error and the file stays as it was.

plugins/memory/honcho/__init__.py

@@ -166,11 +166,14 @@ class HonchoMemoryProvider(DialecticMixin, MemoryProvider):
             return False
 
     def save_config(self, values, hermes_home):
-        """Merge ``values`` into $HERMES_HOME/honcho.json (Honcho SDK native format)."""
+        """Merge ``values`` into $HERMES_HOME/honcho.json (Honcho SDK native format).
+        A file that exists but does not parse raises instead of being replaced by ``values`` alone."""
         from pathlib import Path
-        from utils import atomic_json_write, read_json_or_empty
+        from utils import atomic_json_write
+        from plugins.memory.honcho.oauth import _read_config_strict
         config_path = Path(hermes_home) / "honcho.json"
-        atomic_json_write(config_path, {**read_json_or_empty(config_path), **values}, mode=0o600)
+        existing = _read_config_strict(config_path)
+        atomic_json_write(config_path, {**existing, **values}, mode=0o600)
 
     def get_config_schema(self):
         return [

tests/test_honcho_client_config.py

@@ -204,3 +204,26 @@ class TestProfileKeyIsolationWarning:
                 host='hermes', config_path=config_path,
             )
         assert not any('NOT inherited' in r.message for r in caplog.records)
+
+
+def test_save_config_refuses_to_replace_a_file_that_does_not_parse(tmp_path, monkeypatch):
+    """A corrupt honcho.json must not be rewritten from the new values alone."""
+    import pytest
+    from plugins.memory.honcho import HonchoMemoryProvider
+
+    config_path = tmp_path / "honcho.json"
+    config_path.write_text("{ not json")
+    provider = HonchoMemoryProvider()
+    with pytest.raises(ValueError):
+        provider.save_config({"api_key": "hc-test-key"}, str(tmp_path))
+    assert config_path.read_text() == "{ not json"
+
+
+def test_save_config_merges_into_a_parseable_file(tmp_path):
+    from plugins.memory.honcho import HonchoMemoryProvider
+
+    config_path = tmp_path / "honcho.json"
+    config_path.write_text(json.dumps({"hosts": {"other": {"apiKey": "keep-me"}}}))
+    HonchoMemoryProvider().save_config({"api_key": "hc-test-key"}, str(tmp_path))
+    data = json.loads(config_path.read_text())
+    assert data["hosts"]["other"]["apiKey"] == "keep-me" and data["api_key"] == "hc-test-key"