fix: cover MCP reconnect edge cases

maintainer edit: handle prompt sessions that report Connection closed outside McpError, and match reconnect registration prefixes with the same sanitization used by MCP wrapper names.

tests/agent/test_mcp_connection.py

@@ -288,6 +288,55 @@ async def test_mcp_tool_reconnects_after_session_terminated(
     assert loop.tools.get("mcp_remote_quote") is not old_tool
 
 
+@pytest.mark.asyncio
+async def test_mcp_reconnect_handler_uses_sanitized_server_prefix(
+    tmp_path,
+    monkeypatch: pytest.MonkeyPatch,
+):
+    loop = _make_loop(tmp_path, mcp_servers={"remote_": object()})
+    connect_count = 0
+
+    class _FakeSession:
+        def __init__(self, index: int) -> None:
+            self.index = index
+
+        async def call_tool(self, _name: str, arguments: dict[str, Any]) -> Any:
+            assert arguments == {}
+            if self.index == 1:
+                raise McpError(ErrorData(code=-32000, message="Session terminated"))
+            return SimpleNamespace(
+                content=[mcp_types.TextContent(type="text", text="recovered")]
+            )
+
+    async def _fake_connect(servers, registry):
+        nonlocal connect_count
+        stacks = {}
+        for name in servers:
+            connect_count += 1
+            tool_def = SimpleNamespace(
+                name="quote",
+                description="quote tool",
+                inputSchema={"type": "object", "properties": {}},
+            )
+            registry.register(MCPToolWrapper(_FakeSession(connect_count), name, tool_def))
+            stack = AsyncExitStack()
+            await stack.__aenter__()
+            stacks[name] = stack
+        return stacks
+
+    monkeypatch.setattr("nanobot.agent.tools.mcp.connect_mcp_servers", _fake_connect)
+
+    await loop._connect_mcp()
+    old_tool = loop.tools.get("mcp_remote_quote")
+    assert isinstance(old_tool, MCPToolWrapper)
+
+    output = await old_tool.execute()
+
+    assert output == "recovered"
+    assert connect_count == 2
+    assert loop.tools.get("mcp_remote_quote") is not old_tool
+
+
 @pytest.mark.asyncio
 async def test_concurrent_mcp_reconnect_reuses_fresh_session(
     tmp_path,