feat(agent): make model presets session-scoped (#4866)

tests/agent/tools/test_self_tool.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import time
 from pathlib import Path
+from types import MappingProxyType
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -11,6 +12,7 @@ from pydantic import BaseModel
 
 from nanobot.agent.tools.context import RequestContext, request_context
 from nanobot.agent.tools.self import MyTool
+from nanobot.config.schema import ModelPresetConfig
 
 # ---------------------------------------------------------------------------
 # Helpers
@@ -1078,6 +1080,32 @@ class TestSecurityAttributeProtection:
         result = await tool.execute(action="set", key="web_config.enable", value=False)
         assert "read-only" in result
 
+    @pytest.mark.asyncio
+    async def test_modify_model_presets_dotpath_blocked(self):
+        """The config-derived model preset catalog is inspectable but not mutable."""
+        presets = {"fast": {"model": "fast-model"}}
+        tool = _make_tool(runtime_state=_make_mock_loop(model_presets=presets))
+
+        result = await tool.execute(
+            action="set",
+            key="model_presets.other",
+            value={"model": "other-model"},
+        )
+
+        assert "read-only" in result
+        assert presets == {"fast": {"model": "fast-model"}}
+
+    @pytest.mark.asyncio
+    async def test_inspect_read_only_model_preset_dotpath(self):
+        presets = MappingProxyType({
+            "fast": ModelPresetConfig(model="fast-model"),
+        })
+        tool = _make_tool(runtime_state=_make_mock_loop(model_presets=presets))
+
+        result = await tool.execute(action="check", key="model_presets.fast.model")
+
+        assert result == "model_presets.fast.model: 'fast-model'"
+
 
 # ---------------------------------------------------------------------------
 # current iteration count (Fix #2)