Add native chat background and guarded HA YAML access

dev/test_hass_mcp_yaml_guard.py

@@ -0,0 +1,91 @@
+#!/usr/bin/env python3
+"""Dependency-free safety checks for the hass_mcp YAML overlay."""
+
+from __future__ import annotations
+
+import importlib.util
+import pathlib
+import sys
+import types
+
+
+def module(name: str, **attributes):
+    value = types.ModuleType(name)
+    for key, item in attributes.items():
+        setattr(value, key, item)
+    sys.modules[name] = value
+    return value
+
+
+class ToolError(Exception):
+    pass
+
+
+def decorator(**_kwargs):
+    return lambda function: function
+
+
+module("homeassistant")
+module("homeassistant.core", HomeAssistant=object)
+module("homeassistant.util", slugify=lambda value: str(value).lower().replace(" ", "_"))
+module("guarded")
+module("guarded.tools")
+module("guarded.identity", user_context=lambda: None)
+module("guarded.protocol", ToolError=ToolError, internal_error=lambda message, error: RuntimeError(f"{message}: {error}"))
+module(
+    "guarded.registry",
+    LIMIT_FIELD={"type": "integer"},
+    OFFSET_FIELD={"type": "integer"},
+    paginate=lambda items, limit, offset: {"items": items[offset : offset + limit]},
+    schema=lambda **kwargs: kwargs,
+    tool=decorator,
+)
+
+source = pathlib.Path(__file__).parents[1] / "platform/mcp/patches/hass_mcp/yaml_config.py"
+spec = importlib.util.spec_from_file_location("guarded.tools.yaml_config", source)
+assert spec and spec.loader
+guard = importlib.util.module_from_spec(spec)
+sys.modules[spec.name] = guard
+spec.loader.exec_module(guard)
+
+assert set(guard._KINDS) == {"automation", "script", "scene", "configuration"}
+assert all("secret" not in filename for filename, _, _ in guard._KINDS.values())
+assert guard._redact_line("api_key: abc") == "api_key: <redacted>"
+assert guard._redact_line("token: abc") == "token: <redacted>"
+assert guard._redact_line("value: !secret private_name") == "value: !secret <redacted-reference>"
+assert guard._redact_line("alias: Safe automation") == "alias: Safe automation"
+
+for sensitive in ("token: abc", "password: abc", "value: !secret private_name"):
+    try:
+        guard._reject_sensitive_replacement(sensitive)
+    except ToolError:
+        pass
+    else:
+        raise AssertionError(f"sensitive replacement was accepted: {sensitive}")
+
+change = guard._change_record("automation", "update", "before", {"id": "demo"})
+preview = guard._preview(change)
+assert preview["changed"] is False
+assert preview["confirmation_required"] is True
+guard._consume_ticket(change, preview["approval_ticket"])
+try:
+    guard._consume_ticket(change, preview["approval_ticket"])
+except ToolError:
+    pass
+else:
+    raise AssertionError("one-time approval ticket was reusable")
+
+other = guard._change_record("automation", "update", "different", {"id": "demo"})
+ticket = guard._preview(change)["approval_ticket"]
+try:
+    guard._consume_ticket(other, ticket)
+except ToolError:
+    pass
+else:
+    raise AssertionError("ticket accepted a different current file fingerprint")
+
+diff = guard._source_diff("automations.yaml", "a\nb\n", "a\nc\n")
+assert any("-b" in line for line in diff)
+assert any("+c" in line for line in diff)
+
+print("hass_mcp_yaml_guard_tests=ok")