Move to multi-connection modality

app/config.py

@@ -1,6 +1,7 @@
 import logging
 from typing import Literal
 
+from pydantic import model_validator
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
 
@@ -9,9 +10,39 @@ class Settings(BaseSettings):
 
     serial_port: str = ""  # Empty string triggers auto-detection
     serial_baudrate: int = 115200
+    tcp_host: str = ""
+    tcp_port: int = 4000
+    ble_address: str = ""
+    ble_pin: str = ""
     log_level: Literal["DEBUG", "INFO", "WARNING", "ERROR"] = "INFO"
     database_path: str = "data/meshcore.db"
 
+    @model_validator(mode="after")
+    def validate_transport_exclusivity(self) -> "Settings":
+        transports_set = sum(
+            [
+                bool(self.serial_port),
+                bool(self.tcp_host),
+                bool(self.ble_address),
+            ]
+        )
+        if transports_set > 1:
+            raise ValueError(
+                "Only one transport may be configured at a time. "
+                "Set exactly one of MESHCORE_SERIAL_PORT, MESHCORE_TCP_HOST, or MESHCORE_BLE_ADDRESS."
+            )
+        if self.ble_address and not self.ble_pin:
+            raise ValueError("MESHCORE_BLE_PIN is required when MESHCORE_BLE_ADDRESS is set.")
+        return self
+
+    @property
+    def connection_type(self) -> Literal["serial", "tcp", "ble"]:
+        if self.tcp_host:
+            return "tcp"
+        if self.ble_address:
+            return "ble"
+        return "serial"
+
 
 settings = Settings()