feat(config): hot reload agent runtime settings

AGENTS.md

@@ -32,6 +32,7 @@ Do not commit real API keys, tokens, chat logs, or workspace data. Keep local se
 - If a slash command should appear in Telegram's native command menu, also update `nanobot/channels/telegram.py`.
 - `/skill` currently supports `search`, `install`, `uninstall`, `list`, and `update`. Keep subcommand dispatch in `nanobot/agent/loop.py`.
 - `/mcp` supports the default `list` behavior (and explicit `/mcp list`) to show configured MCP servers and registered MCP tools.
+- Agent runtime config should be hot-reloaded from the active `config.json` for safe in-process fields such as `tools.mcpServers`, `tools.web.*`, `tools.exec.*`, `tools.restrictToWorkspace`, `agents.defaults.model`, `agents.defaults.maxToolIterations`, `agents.defaults.contextWindowTokens`, `agents.defaults.maxTokens`, `agents.defaults.temperature`, `agents.defaults.reasoningEffort`, `channels.sendProgress`, and `channels.sendToolHints`. Channel connection settings and provider credentials still require a restart.
 - `/skill` shells out to `npx clawhub@latest`; it requires Node.js/`npx` at runtime.
 - `/skill uninstall` runs in a non-interactive context, so keep passing `--yes` when shelling out to ClawHub.
 - Treat empty `/skill search` output as a user-visible "no results" case rather than a silent success. Surface npm/registry failures directly to the user.

README.md

@@ -1187,6 +1187,7 @@ Use `toolTimeout` to override the default 30s per-call timeout for slow servers:
 ```
 
 MCP tools are automatically discovered and registered on startup. The LLM can use them alongside built-in tools — no extra configuration needed.
+nanobot hot-reloads agent runtime config from the active `config.json` on the next message, including `tools.mcpServers`, `tools.web.*`, `tools.exec.*`, `tools.restrictToWorkspace`, `agents.defaults.model`, `agents.defaults.maxToolIterations`, `agents.defaults.contextWindowTokens`, `agents.defaults.maxTokens`, `agents.defaults.temperature`, `agents.defaults.reasoningEffort`, `channels.sendProgress`, and `channels.sendToolHints`. Channel connection settings and provider credentials still require a restart.
 
 
 

nanobot/agent/loop.py

@@ -77,6 +77,7 @@ class AgentLoop:
         bus: MessageBus,
         provider: LLMProvider,
         workspace: Path,
+        config_path: Path | None = None,
         model: str | None = None,
         max_iterations: int = 40,
         context_window_tokens: int = 65_536,
@@ -97,6 +98,7 @@ class AgentLoop:
         self.channels_config = channels_config
         self.provider = provider
         self.workspace = workspace
+        self.config_path = config_path
         self.model = model or provider.get_default_model()
         self.max_iterations = max_iterations
         self.context_window_tokens = context_window_tokens
@@ -128,6 +130,9 @@ class AgentLoop:
 
         self._running = False
         self._mcp_servers = mcp_servers or {}
+        self._runtime_config_mtime_ns = (
+            config_path.stat().st_mtime_ns if config_path and config_path.exists() else None
+        )
         self._mcp_stack: AsyncExitStack | None = None
         self._mcp_connected = False
         self._mcp_connecting = False
@@ -212,6 +217,142 @@ class AgentLoop:
 
         return {name: sorted(tools) for name, tools in grouped.items()}
 
+    def _remove_registered_mcp_tools(self) -> None:
+        """Remove all dynamically registered MCP tools from the registry."""
+        for tool_name in list(self.tools.tool_names):
+            if tool_name.startswith("mcp_"):
+                self.tools.unregister(tool_name)
+
+    @staticmethod
+    def _dump_mcp_servers(servers: dict) -> dict:
+        """Normalize MCP server config for value-based comparisons."""
+        dumped = {}
+        for name, cfg in servers.items():
+            dumped[name] = cfg.model_dump() if hasattr(cfg, "model_dump") else cfg
+        return dumped
+
+    async def _reset_mcp_connections(self) -> None:
+        """Drop MCP tool registrations and close active MCP connections."""
+        self._remove_registered_mcp_tools()
+        if self._mcp_stack:
+            try:
+                await self._mcp_stack.aclose()
+            except (RuntimeError, BaseExceptionGroup):
+                pass
+            self._mcp_stack = None
+        self._mcp_connected = False
+        self._mcp_connecting = False
+
+    def _apply_runtime_tool_config(self) -> None:
+        """Apply runtime-configurable settings to already-registered tools."""
+        allowed_dir = self.workspace if self.restrict_to_workspace else None
+        extra_read = [BUILTIN_SKILLS_DIR] if allowed_dir else None
+
+        if read_tool := self.tools.get("read_file"):
+            read_tool._workspace = self.workspace
+            read_tool._allowed_dir = allowed_dir
+            read_tool._extra_allowed_dirs = extra_read
+
+        for name in ("write_file", "edit_file", "list_dir"):
+            if tool := self.tools.get(name):
+                tool._workspace = self.workspace
+                tool._allowed_dir = allowed_dir
+                tool._extra_allowed_dirs = None
+
+        if exec_tool := self.tools.get("exec"):
+            exec_tool.timeout = self.exec_config.timeout
+            exec_tool.working_dir = str(self.workspace)
+            exec_tool.restrict_to_workspace = self.restrict_to_workspace
+            exec_tool.path_append = self.exec_config.path_append
+
+        if web_search_tool := self.tools.get("web_search"):
+            web_search_tool._init_provider = self.web_search_provider
+            web_search_tool._init_api_key = self.brave_api_key
+            web_search_tool._init_base_url = self.web_search_base_url
+            web_search_tool.max_results = self.web_search_max_results
+            web_search_tool.proxy = self.web_proxy
+
+        if web_fetch_tool := self.tools.get("web_fetch"):
+            web_fetch_tool.proxy = self.web_proxy
+
+    def _apply_runtime_config(self, config) -> bool:
+        """Apply hot-reloadable config to the current agent instance."""
+        from nanobot.providers.base import GenerationSettings
+
+        defaults = config.agents.defaults
+        tools_cfg = config.tools
+        web_cfg = tools_cfg.web
+        search_cfg = web_cfg.search
+
+        self.model = defaults.model
+        self.max_iterations = defaults.max_tool_iterations
+        self.context_window_tokens = defaults.context_window_tokens
+        self.exec_config = tools_cfg.exec
+        self.restrict_to_workspace = tools_cfg.restrict_to_workspace
+        self.brave_api_key = search_cfg.api_key or None
+        self.web_proxy = web_cfg.proxy or None
+        self.web_search_provider = search_cfg.provider
+        self.web_search_base_url = search_cfg.base_url or None
+        self.web_search_max_results = search_cfg.max_results
+        self.channels_config = config.channels
+
+        self.provider.generation = GenerationSettings(
+            temperature=defaults.temperature,
+            max_tokens=defaults.max_tokens,
+            reasoning_effort=defaults.reasoning_effort,
+        )
+        if hasattr(self.provider, "default_model"):
+            self.provider.default_model = self.model
+        self.memory_consolidator.model = self.model
+        self.memory_consolidator.context_window_tokens = self.context_window_tokens
+        self.subagents.apply_runtime_config(
+            model=self.model,
+            brave_api_key=self.brave_api_key,
+            web_proxy=self.web_proxy,
+            web_search_provider=self.web_search_provider,
+            web_search_base_url=self.web_search_base_url,
+            web_search_max_results=self.web_search_max_results,
+            exec_config=self.exec_config,
+            restrict_to_workspace=self.restrict_to_workspace,
+        )
+        self._apply_runtime_tool_config()
+
+        mcp_changed = self._dump_mcp_servers(config.tools.mcp_servers) != self._dump_mcp_servers(
+            self._mcp_servers
+        )
+        self._mcp_servers = config.tools.mcp_servers
+        return mcp_changed
+
+    async def _reload_runtime_config_if_needed(self, *, force: bool = False) -> None:
+        """Reload hot-reloadable config from the active config file when it changes."""
+        if self.config_path is None:
+            return
+
+        try:
+            mtime_ns = self.config_path.stat().st_mtime_ns
+        except FileNotFoundError:
+            mtime_ns = None
+
+        if not force and mtime_ns == self._runtime_config_mtime_ns:
+            return
+
+        self._runtime_config_mtime_ns = mtime_ns
+
+        from nanobot.config.loader import load_config
+
+        if mtime_ns is None:
+            await self._reset_mcp_connections()
+            self._mcp_servers = {}
+            return
+
+        reloaded = load_config(self.config_path)
+        if self._apply_runtime_config(reloaded):
+            await self._reset_mcp_connections()
+
+    async def _reload_mcp_servers_if_needed(self, *, force: bool = False) -> None:
+        """Backward-compatible wrapper for runtime config reloads."""
+        await self._reload_runtime_config_if_needed(force=force)
+
     @staticmethod
     def _decode_subprocess_output(data: bytes) -> str:
         """Decode subprocess output conservatively for CLI surfacing."""
@@ -396,6 +537,8 @@ class AgentLoop:
                 content=self._mcp_usage(language),
             )
 
+        await self._reload_mcp_servers_if_needed()
+
         if not self._mcp_servers:
             return OutboundMessage(
                 channel=msg.channel,
@@ -456,6 +599,7 @@ class AgentLoop:
 
     async def _connect_mcp(self) -> None:
         """Connect to configured MCP servers (one-time, lazy)."""
+        await self._reload_mcp_servers_if_needed()
         if self._mcp_connected or self._mcp_connecting or not self._mcp_servers:
             return
         self._mcp_connecting = True
@@ -791,12 +935,7 @@ class AgentLoop:
         if self._background_tasks:
             await asyncio.gather(*self._background_tasks, return_exceptions=True)
             self._background_tasks.clear()
-        if self._mcp_stack:
+        await self._reset_mcp_connections()
-            try:
-                await self._mcp_stack.aclose()
-            except (RuntimeError, BaseExceptionGroup):
-                pass  # MCP SDK cancel scope cleanup is noisy but harmless
-            self._mcp_stack = None
 
     def _schedule_background(self, coro) -> None:
         """Schedule a coroutine as a tracked background task (drained on shutdown)."""
@@ -816,6 +955,8 @@ class AgentLoop:
         on_progress: Callable[[str], Awaitable[None]] | None = None,
     ) -> OutboundMessage | None:
         """Process a single inbound message and return the response."""
+        await self._reload_runtime_config_if_needed()
+
         # System messages: parse origin from chat_id ("channel:chat_id")
         if msg.channel == "system":
             channel, chat_id = (msg.chat_id.split(":", 1) if ":" in msg.chat_id
@@ -825,6 +966,7 @@ class AgentLoop:
             session = self.sessions.get_or_create(key)
             persona = self._get_session_persona(session)
             language = self._get_session_language(session)
+            await self._connect_mcp()
             await self.memory_consolidator.maybe_consolidate_by_tokens(session)
             self._set_tool_context(channel, chat_id, msg.metadata.get("message_id"))
             history = session.get_history(max_messages=0)
@@ -879,6 +1021,7 @@ class AgentLoop:
             return OutboundMessage(
                 channel=msg.channel, chat_id=msg.chat_id, content="\n".join(help_lines(language)),
             )
+        await self._connect_mcp()
         await self.memory_consolidator.maybe_consolidate_by_tokens(session)
 
         self._set_tool_context(msg.channel, msg.chat_id, msg.metadata.get("message_id"))

nanobot/agent/subagent.py

@@ -52,6 +52,28 @@ class SubagentManager:
         self._running_tasks: dict[str, asyncio.Task[None]] = {}
         self._session_tasks: dict[str, set[str]] = {}  # session_key -> {task_id, ...}
 
+    def apply_runtime_config(
+        self,
+        *,
+        model: str,
+        brave_api_key: str | None,
+        web_proxy: str | None,
+        web_search_provider: str,
+        web_search_base_url: str | None,
+        web_search_max_results: int,
+        exec_config: ExecToolConfig,
+        restrict_to_workspace: bool,
+    ) -> None:
+        """Update runtime-configurable settings for future subagent tasks."""
+        self.model = model
+        self.brave_api_key = brave_api_key
+        self.web_proxy = web_proxy
+        self.web_search_provider = web_search_provider
+        self.web_search_base_url = web_search_base_url
+        self.web_search_max_results = web_search_max_results
+        self.exec_config = exec_config
+        self.restrict_to_workspace = restrict_to_workspace
+
     async def spawn(
         self,
         task: str,
@@ -209,7 +231,7 @@ Summarize this naturally for the user. Keep it brief (1-2 sentences). Do not men
 
         await self.bus.publish_inbound(msg)
         logger.debug("Subagent [{}] announced result to {}:{}", task_id, origin['channel'], origin['chat_id'])
-    
+
     def _build_subagent_prompt(self) -> str:
         """Build a focused system prompt for the subagent."""
         from nanobot.agent.context import ContextBuilder

nanobot/agent/tools/web.py

@@ -118,7 +118,7 @@ class WebSearchTool(Tool):
             return (
                 "Error: Brave Search API key not configured. Set it in "
                 "~/.nanobot/config.json under tools.web.search.apiKey "
-                "(or export BRAVE_API_KEY), then restart the gateway."
+                "(or export BRAVE_API_KEY), then retry your message."
             )
 
         try:

nanobot/cli/commands.py

@@ -491,6 +491,7 @@ def gateway(
     from nanobot.agent.loop import AgentLoop
     from nanobot.bus.queue import MessageBus
     from nanobot.channels.manager import ChannelManager
+    from nanobot.config.loader import get_config_path
     from nanobot.config.paths import get_cron_dir
     from nanobot.cron.service import CronService
     from nanobot.cron.types import CronJob
@@ -520,6 +521,7 @@ def gateway(
         bus=bus,
         provider=provider,
         workspace=config.workspace_path,
+        config_path=get_config_path(),
         model=config.agents.defaults.model,
         max_iterations=config.agents.defaults.max_tool_iterations,
         context_window_tokens=config.agents.defaults.context_window_tokens,
@@ -683,6 +685,7 @@ def agent(
 
     from nanobot.agent.loop import AgentLoop
     from nanobot.bus.queue import MessageBus
+    from nanobot.config.loader import get_config_path
     from nanobot.config.paths import get_cron_dir
     from nanobot.cron.service import CronService
 
@@ -706,6 +709,7 @@ def agent(
         bus=bus,
         provider=provider,
         workspace=config.workspace_path,
+        config_path=get_config_path(),
         model=config.agents.defaults.model,
         max_iterations=config.agents.defaults.max_tool_iterations,
         context_window_tokens=config.agents.defaults.context_window_tokens,

tests/test_mcp_commands.py

@@ -2,7 +2,9 @@
 
 from __future__ import annotations
 
+import json
 from pathlib import Path
+from types import SimpleNamespace
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
@@ -30,7 +32,7 @@ class _FakeTool:
         return ""
 
 
-def _make_loop(workspace: Path, *, mcp_servers: dict | None = None):
+def _make_loop(workspace: Path, *, mcp_servers: dict | None = None, config_path: Path | None = None):
     """Create an AgentLoop with a real workspace and lightweight mocks."""
     from nanobot.agent.loop import AgentLoop
     from nanobot.bus.queue import MessageBus
@@ -40,7 +42,13 @@ def _make_loop(workspace: Path, *, mcp_servers: dict | None = None):
     provider.get_default_model.return_value = "test-model"
 
     with patch("nanobot.agent.loop.SubagentManager"):
-        loop = AgentLoop(bus=bus, provider=provider, workspace=workspace, mcp_servers=mcp_servers)
+        loop = AgentLoop(
+            bus=bus,
+            provider=provider,
+            workspace=workspace,
+            config_path=config_path,
+            mcp_servers=mcp_servers,
+        )
     return loop
 
 
@@ -87,3 +95,246 @@ async def test_help_includes_mcp_command(tmp_path: Path) -> None:
 
     assert response is not None
     assert "/mcp [list]" in response.content
+
+
+@pytest.mark.asyncio
+async def test_mcp_command_hot_reloads_servers_from_config(tmp_path: Path) -> None:
+    config_path = tmp_path / "config.json"
+    config_path.write_text(json.dumps({"tools": {}}), encoding="utf-8")
+    loop = _make_loop(tmp_path, mcp_servers={}, config_path=config_path)
+
+    config_path.write_text(
+        json.dumps(
+            {
+                "tools": {
+                    "mcpServers": {
+                        "docs": {
+                            "command": "npx",
+                            "args": ["-y", "@demo/docs"],
+                        }
+                    }
+                }
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    with patch.object(loop, "_connect_mcp", AsyncMock()) as connect_mcp:
+        response = await loop._process_message(
+            InboundMessage(channel="cli", sender_id="user", chat_id="direct", content="/mcp")
+        )
+
+    assert response is not None
+    assert "Configured MCP servers:" in response.content
+    assert "- docs" in response.content
+    connect_mcp.assert_awaited_once()
+
+
+@pytest.mark.asyncio
+async def test_mcp_config_reload_resets_connections_and_tools(tmp_path: Path) -> None:
+    config_path = tmp_path / "config.json"
+    config_path.write_text(
+        json.dumps(
+            {
+                "tools": {
+                    "mcpServers": {
+                        "old": {
+                            "command": "npx",
+                            "args": ["-y", "@demo/old"],
+                        }
+                    }
+                }
+            }
+        ),
+        encoding="utf-8",
+    )
+    loop = _make_loop(
+        tmp_path,
+        mcp_servers={"old": SimpleNamespace(model_dump=lambda: {"command": "npx", "args": ["-y", "@demo/old"]})},
+        config_path=config_path,
+    )
+    stack = SimpleNamespace(aclose=AsyncMock())
+    loop._mcp_stack = stack
+    loop._mcp_connected = True
+    loop.tools.register(_FakeTool("mcp_old_lookup"))
+
+    config_path.write_text(
+        json.dumps(
+            {
+                "tools": {
+                    "mcpServers": {
+                        "new": {
+                            "command": "npx",
+                            "args": ["-y", "@demo/new"],
+                        }
+                    }
+                }
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    await loop._reload_mcp_servers_if_needed(force=True)
+
+    assert list(loop._mcp_servers) == ["new"]
+    assert loop._mcp_connected is False
+    assert loop.tools.get("mcp_old_lookup") is None
+    stack.aclose.assert_awaited_once()
+
+
+@pytest.mark.asyncio
+async def test_regular_messages_pick_up_reloaded_mcp_config(tmp_path: Path, monkeypatch) -> None:
+    config_path = tmp_path / "config.json"
+    config_path.write_text(json.dumps({"tools": {}}), encoding="utf-8")
+    loop = _make_loop(tmp_path, mcp_servers={}, config_path=config_path)
+
+    loop.provider.chat_with_retry = AsyncMock(
+        return_value=SimpleNamespace(
+            has_tool_calls=False,
+            content="ok",
+            finish_reason="stop",
+            reasoning_content=None,
+            thinking_blocks=None,
+        )
+    )
+
+    config_path.write_text(
+        json.dumps(
+            {
+                "tools": {
+                    "mcpServers": {
+                        "docs": {
+                            "command": "npx",
+                            "args": ["-y", "@demo/docs"],
+                        }
+                    }
+                }
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    connect_mcp_servers = AsyncMock()
+    monkeypatch.setattr("nanobot.agent.tools.mcp.connect_mcp_servers", connect_mcp_servers)
+
+    response = await loop._process_message(
+        InboundMessage(channel="cli", sender_id="user", chat_id="direct", content="hello")
+    )
+
+    assert response is not None
+    assert response.content == "ok"
+    assert list(loop._mcp_servers) == ["docs"]
+    connect_mcp_servers.assert_awaited_once()
+
+
+@pytest.mark.asyncio
+async def test_runtime_config_reload_updates_agent_and_tool_settings(tmp_path: Path) -> None:
+    config_path = tmp_path / "config.json"
+    config_path.write_text(
+        json.dumps(
+            {
+                "agents": {
+                    "defaults": {
+                        "model": "initial-model",
+                        "maxToolIterations": 4,
+                        "contextWindowTokens": 4096,
+                        "maxTokens": 1000,
+                        "temperature": 0.2,
+                        "reasoningEffort": "low",
+                    }
+                },
+                "tools": {
+                    "restrictToWorkspace": False,
+                    "exec": {"timeout": 20, "pathAppend": ""},
+                    "web": {
+                        "proxy": "",
+                        "search": {
+                            "provider": "brave",
+                            "apiKey": "",
+                            "baseUrl": "",
+                            "maxResults": 3,
+                        }
+                    },
+                },
+                "channels": {
+                    "sendProgress": True,
+                    "sendToolHints": False,
+                },
+            }
+        ),
+        encoding="utf-8",
+    )
+    loop = _make_loop(tmp_path, mcp_servers={}, config_path=config_path)
+
+    config_path.write_text(
+        json.dumps(
+            {
+                "agents": {
+                    "defaults": {
+                        "model": "reloaded-model",
+                        "maxToolIterations": 9,
+                        "contextWindowTokens": 8192,
+                        "maxTokens": 2222,
+                        "temperature": 0.7,
+                        "reasoningEffort": "high",
+                    }
+                },
+                "tools": {
+                    "restrictToWorkspace": True,
+                    "exec": {"timeout": 45, "pathAppend": "/usr/local/bin"},
+                    "web": {
+                        "proxy": "http://127.0.0.1:7890",
+                        "search": {
+                            "provider": "searxng",
+                            "apiKey": "demo-key",
+                            "baseUrl": "https://search.example.com",
+                            "maxResults": 7,
+                        }
+                    },
+                },
+                "channels": {
+                    "sendProgress": False,
+                    "sendToolHints": True,
+                },
+            }
+        ),
+        encoding="utf-8",
+    )
+
+    await loop._reload_runtime_config_if_needed(force=True)
+
+    exec_tool = loop.tools.get("exec")
+    web_search_tool = loop.tools.get("web_search")
+    web_fetch_tool = loop.tools.get("web_fetch")
+    read_tool = loop.tools.get("read_file")
+
+    assert loop.model == "reloaded-model"
+    assert loop.max_iterations == 9
+    assert loop.context_window_tokens == 8192
+    assert loop.provider.generation.max_tokens == 2222
+    assert loop.provider.generation.temperature == 0.7
+    assert loop.provider.generation.reasoning_effort == "high"
+    assert loop.memory_consolidator.model == "reloaded-model"
+    assert loop.memory_consolidator.context_window_tokens == 8192
+    assert loop.channels_config.send_progress is False
+    assert loop.channels_config.send_tool_hints is True
+    loop.subagents.apply_runtime_config.assert_called_once_with(
+        model="reloaded-model",
+        brave_api_key="demo-key",
+        web_proxy="http://127.0.0.1:7890",
+        web_search_provider="searxng",
+        web_search_base_url="https://search.example.com",
+        web_search_max_results=7,
+        exec_config=loop.exec_config,
+        restrict_to_workspace=True,
+    )
+    assert exec_tool.timeout == 45
+    assert exec_tool.path_append == "/usr/local/bin"
+    assert exec_tool.restrict_to_workspace is True
+    assert web_search_tool._init_provider == "searxng"
+    assert web_search_tool._init_api_key == "demo-key"
+    assert web_search_tool._init_base_url == "https://search.example.com"
+    assert web_search_tool.max_results == 7
+    assert web_search_tool.proxy == "http://127.0.0.1:7890"
+    assert web_fetch_tool.proxy == "http://127.0.0.1:7890"
+    assert read_tool._allowed_dir == tmp_path