diff --git a/pico-dashboard/comms/communication_service.py b/pico-dashboard/comms/communication_service.py
new file mode 100644
index 0000000..32a2de1
--- /dev/null
+++ b/pico-dashboard/comms/communication_service.py
@@ -0,0 +1,48 @@
+from .protocol import (
+    make_status_request,
+    make_set_relay,
+    is_status_response,
+    is_relay_response,
+    is_error,
+)
+
+
+class CommunicationService:
+    def __init__(self, uart_client, app_state):
+        self.uart_client = uart_client
+        self.app_state = app_state
+        self.last_messages = []
+
+    def request_status(self):
+        self.uart_client.send_message(make_status_request())
+
+    def set_relay(self, relay, enabled):
+        self.uart_client.send_message(make_set_relay(relay, enabled))
+
+    def poll(self):
+        messages = self.uart_client.read_available_messages()
+        self.last_messages = messages
+
+        for message in messages:
+            self.handle_message(message)
+
+        return messages
+
+    def handle_message(self, message):
+        if is_status_response(message):
+            self.app_state.update_from_status(message)
+            return
+
+        if is_relay_response(message):
+            self.app_state.update_from_relay_response(message)
+            return
+
+        if is_error(message):
+            self.app_state.set_error(message)
+            return
+
+        self.app_state.set_error({
+            "type": "error",
+            "message": "unknown_message_type",
+            "raw": message,
+        })
diff --git a/tests/test_pico_core.py b/tests/test_pico_core.py
index 1b121a4..53943b7 100644
--- a/tests/test_pico_core.py
+++ b/tests/test_pico_core.py
@@ -150,3 +150,81 @@ def test_uart_client_handles_invalid_json():
 
     assert messages[0]["type"] == "error"
     assert messages[0]["message"] == "invalid_json"
+
+
+def test_communication_service_requests_status():
+    from comms.uart_client import UartClient
+    from comms.communication_service import CommunicationService
+
+    fake = FakeUart()
+    state = AppState()
+    service = CommunicationService(UartClient(fake), state)
+
+    service.request_status()
+
+    assert fake.writes == [b'{"type":"status_request"}\n']
+
+
+def test_communication_service_sends_relay_command():
+    from comms.uart_client import UartClient
+    from comms.communication_service import CommunicationService
+
+    fake = FakeUart()
+    state = AppState()
+    service = CommunicationService(UartClient(fake), state)
+
+    service.set_relay("fridge", False)
+
+    assert fake.writes == [b'{"type":"set_relay","relay":"fridge","enabled":false}\n']
+
+
+def test_communication_service_updates_state_from_status():
+    from comms.uart_client import UartClient
+    from comms.communication_service import CommunicationService
+
+    fake = FakeUart()
+    fake.read_chunks = [
+        b'{"type":"status_response","timestamp":99,"battery":{"soc":75},"network":{"uart_connected":true}}\n'
+    ]
+
+    state = AppState()
+    service = CommunicationService(UartClient(fake), state)
+
+    messages = service.poll()
+
+    assert messages[0]["type"] == "status_response"
+    assert state.last_status_timestamp == 99
+    assert state.battery["soc"] == 75
+    assert state.network["uart_connected"] is True
+
+
+def test_communication_service_updates_state_from_relay_response():
+    from comms.uart_client import UartClient
+    from comms.communication_service import CommunicationService
+
+    fake = FakeUart()
+    fake.read_chunks = [
+        b'{"type":"relay_response","relay":"starlink","enabled":true,"ok":true}\n'
+    ]
+
+    state = AppState()
+    service = CommunicationService(UartClient(fake), state)
+
+    service.poll()
+
+    assert state.relays["starlink"] is True
+
+
+def test_communication_service_records_errors():
+    from comms.uart_client import UartClient
+    from comms.communication_service import CommunicationService
+
+    fake = FakeUart()
+    fake.read_chunks = [b'{"type":"error","message":"invalid_json"}\n']
+
+    state = AppState()
+    service = CommunicationService(UartClient(fake), state)
+
+    service.poll()
+
+    assert state.last_error["message"] == "invalid_json"