fix(gateway): retry MCP readiness before turns (#5535)

nanobot/cli/gateway_runtime.py

@@ -12,6 +12,7 @@ from loguru import logger
 from rich.console import Console
 
 from nanobot import __logo__, __version__
+from nanobot.agent.hook import AgentHook, AgentRunHookContext
 from nanobot.agent.hooks import create_file_edit_activity_hook
 from nanobot.agent.loop import AgentLoop
 from nanobot.agent.tools.mcp import MCPProvider
@@ -46,6 +47,17 @@ __all__ = ["_run_gateway"]
 console = Console()
 
 
+class _MCPReadinessHook(AgentHook):
+    """Retry application-owned MCP connections before the runner reads tools."""
+
+    def __init__(self, provider: MCPProvider) -> None:
+        super().__init__()
+        self._provider = provider
+
+    async def before_run(self, context: AgentRunHookContext) -> None:
+        await self._provider.connect()
+
+
 def _http_endpoint_responding(url: str, *, timeout_s: float = 0.25) -> bool:
     """Return whether an HTTP endpoint responds, including with an auth error."""
     import urllib.error
@@ -445,6 +457,7 @@ def _run_gateway(
         turn_delivery_factory=turn_delivery_factory,
         provider_signature=provider_snapshot.signature,
         local_trigger_store=trigger_store,
+        hooks=[_MCPReadinessHook(mcp_provider)],
         hook_factories=[create_file_edit_activity_hook],
         tool_registry=tools,
         recovery_admission=recovery,

tests/cli/test_commands.py

@@ -3697,6 +3697,7 @@ def test_gateway_agent_task_owns_initial_mcp_provider_close(
             return cls(**extra)
 
         def __init__(self, **_kwargs) -> None:
+            seen["hooks"] = _kwargs.get("hooks")
             self.model = "test-model"
             self.provider = object()
             self.sessions = _FakeSessionManager()
@@ -3809,6 +3810,11 @@ def test_gateway_agent_task_owns_initial_mcp_provider_close(
     assert mcp_provider.connect_task is seen["agent_task"]
     assert mcp_provider.close_tasks[0] is mcp_provider.connect_task
     assert len(mcp_provider.close_tasks) == 2
+    hooks = seen["hooks"]
+    assert isinstance(hooks, list)
+    assert len(hooks) == 1
+    hook = hooks[0]
+    assert isinstance(hook, cli_gateway_runtime._MCPReadinessHook)
 
 
 def test_gateway_shutdown_event_exits_forever_runtime_tasks(

tests/cli/test_gateway_runtime.py

@@ -11,7 +11,10 @@ import asyncio
 import time
 from contextlib import suppress
 
-from nanobot.cli.gateway_runtime import _close_gateway_runtime
+from nanobot.agent.hook import AgentRunHookContext
+from nanobot.agent.tools.mcp import MCPProvider
+from nanobot.agent.tools.registry import ToolRegistry
+from nanobot.cli.gateway_runtime import _close_gateway_runtime, _MCPReadinessHook
 
 
 class _FakeAgent:
@@ -53,6 +56,24 @@ class _FakeMCPProvider:
         self.events.append("mcp_closed")
 
 
+class _TrackingMCPProvider(MCPProvider):
+    def __init__(self) -> None:
+        super().__init__({}, ToolRegistry())
+        self.connect_calls = 0
+
+    async def connect(self) -> None:
+        self.connect_calls += 1
+
+
+async def test_mcp_readiness_hook_delegates_to_application_provider() -> None:
+    provider = _TrackingMCPProvider()
+    hook = _MCPReadinessHook(provider)
+
+    await hook.before_run(AgentRunHookContext(messages=[]))
+
+    assert provider.connect_calls == 1
+
+
 async def _cancellable_task(events: list[str]) -> None:
     try:
         await asyncio.sleep(3600)