Harden M7.6/7.7: recursive restriction accumulation, MCP server enforcement, fast-fail authorization

tests/test_providers.py

@@ -172,6 +172,20 @@ class TestProviderPersistence:
 
         assert oct(temp_providers_file.stat().st_mode & 0o777) == "0o600"
 
+    def test_malformed_access_policy_fails_closed(self, temp_providers_file, capsys):
+        temp_providers_file.parent.mkdir(parents=True)
+        temp_providers_file.write_text(yaml.safe_dump({
+            "version": 2,
+            "providers": [{
+                "name": "claude",
+                "command": "claude -p",
+                "tools": "should-have-been-a-list",
+            }],
+        }))
+
+        assert load_providers() == []
+        assert "Failed to load provider configuration" in capsys.readouterr().err
+
     def test_legacy_config_gains_missing_defaults_without_losing_custom_provider(self, temp_providers_file):
         temp_providers_file.parent.mkdir(parents=True)
         temp_providers_file.write_text(yaml.safe_dump({
@@ -810,3 +824,28 @@ class TestProviderAccessControl:
         provider = Provider("test", "cmd")
         assert "tools" not in provider.to_dict()
         assert "mcp_servers" not in provider.to_dict()
+
+    def test_empty_allowlists_survive_roundtrip(self):
+        provider = Provider("locked", "cmd", tools=[], mcp_servers=[])
+        serialized = provider.to_dict()
+        assert serialized["tools"] == []
+        assert serialized["mcp_servers"] == []
+
+        restored = Provider.from_dict(serialized)
+        assert restored.tools == []
+        assert restored.mcp_servers == []
+
+    @pytest.mark.parametrize(
+        ("field", "value"),
+        [
+            ("tools", "tool-a"),
+            ("tools", [""]),
+            ("tools", [1]),
+            ("mcp_servers", "filesystem"),
+            ("mcp_servers", [""]),
+            ("mcp_servers", [1]),
+        ],
+    )
+    def test_rejects_invalid_access_policies(self, field, value):
+        with pytest.raises(ValueError, match=field):
+            Provider("test", "cmd", **{field: value})