Better no-connection errors

app/radio.py

@@ -2,17 +2,20 @@ import asyncio
 import glob
 import logging
 import platform
+import re
 from collections import OrderedDict
 from contextlib import asynccontextmanager, nullcontext
 from pathlib import Path
 
 from meshcore import MeshCore
+from serial.serialutil import SerialException
 
 from app.config import settings
 from app.keystore import clear_keys
 
 logger = logging.getLogger(__name__)
 MAX_FRONTEND_RECONNECT_ERROR_BROADCASTS = 3
+_SERIAL_PORT_ERROR_RE = re.compile(r"could not open port (?P<port>.+?):")
 
 
 class RadioOperationError(RuntimeError):
@@ -69,6 +72,36 @@ def detect_serial_devices() -> list[str]:
     return devices
 
 
+def _extract_serial_port_from_error(exc: Exception) -> str | None:
+    """Best-effort extraction of a serial port path from a pyserial error."""
+    message = str(exc)
+    match = _SERIAL_PORT_ERROR_RE.search(message)
+    if match:
+        return match.group("port")
+    return None
+
+
+def _format_reconnect_failure(exc: Exception) -> tuple[str, str, bool]:
+    """Return log message, frontend detail, and whether to log a traceback."""
+    if settings.connection_type == "serial":
+        if isinstance(exc, RuntimeError) and str(exc).startswith("No MeshCore radio found"):
+            message = (
+                "Could not find a MeshCore radio on any serial port. "
+                "Did the radio get disconnected or change serial ports?"
+            )
+            return (message, message, False)
+
+        if isinstance(exc, SerialException):
+            port = settings.serial_port or _extract_serial_port_from_error(exc) or "the serial port"
+            message = (
+                f"Could not connect to serial port {port}. "
+                "Did the radio get disconnected or change serial ports?"
+            )
+            return (message, message, False)
+
+    return (f"Reconnection failed: {exc}", str(exc), True)
+
+
 async def test_serial_device(port: str, baudrate: int, timeout: float = 3.0) -> bool:
     """Test if a MeshCore radio responds on the given serial port."""
     mc = None
@@ -592,8 +625,9 @@ class RadioManager:
                     return False
 
             except Exception as e:
-                logger.warning("Reconnection failed: %s", e, exc_info=True)
-                self._broadcast_reconnect_error_if_needed(str(e))
+                log_message, frontend_detail, include_traceback = _format_reconnect_failure(e)
+                logger.warning(log_message, exc_info=include_traceback)
+                self._broadcast_reconnect_error_if_needed(frontend_detail)
                 return False
 
     async def start_connection_monitor(self) -> None:

tests/test_radio.py

@@ -6,6 +6,7 @@ import asyncio
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
+from serial.serialutil import SerialException
 
 
 class TestRadioManagerConnect:
@@ -509,6 +510,43 @@ class TestReconnectLock:
         for call in mock_broadcast_error.call_args_list:
             assert call.args == ("Reconnection failed", "radio unavailable")
 
+    @pytest.mark.asyncio
+    async def test_reconnect_serial_missing_port_logs_clean_message_without_traceback(self):
+        """Missing serial ports should log a concise operator-facing warning."""
+        from app.radio import RadioManager
+
+        rm = RadioManager()
+        rm.connect = AsyncMock(
+            side_effect=SerialException(
+                2,
+                "could not open port /dev/serial/by-id/test-radio: "
+                "[Errno 2] No such file or directory: '/dev/serial/by-id/test-radio'",
+            )
+        )
+
+        with (
+            patch("app.radio.settings") as mock_settings,
+            patch("app.radio.logger") as mock_logger,
+            patch("app.websocket.broadcast_health"),
+            patch("app.websocket.broadcast_error") as mock_broadcast_error,
+        ):
+            mock_settings.connection_type = "serial"
+            mock_settings.serial_port = "/dev/serial/by-id/test-radio"
+
+            result = await rm.reconnect(broadcast_on_success=False)
+
+        assert result is False
+        mock_logger.warning.assert_called_once_with(
+            "Could not connect to serial port /dev/serial/by-id/test-radio. "
+            "Did the radio get disconnected or change serial ports?",
+            exc_info=False,
+        )
+        assert mock_broadcast_error.call_args.args == (
+            "Reconnection failed",
+            "Could not connect to serial port /dev/serial/by-id/test-radio. "
+            "Did the radio get disconnected or change serial ports?",
+        )
+
 
 class TestManualDisconnectCleanup:
     """Tests for manual disconnect teardown behavior."""