feat: introduce .env.example, docs

The example includes options that are expected to be changed. It also includes a reference to where in the docs you can find a full list of options.

ref: N25B-352

.env.example

@@ -0,0 +1,20 @@
+# Example .env file. To use, make a copy, call it ".env" (i.e. removing the ".example" suffix), then you edit values.
+
+# The hostname of the Robot Interface. Change if the Control Backend and Robot Interface are running on different computers.
+RI_HOST="localhost"
+
+# URL for the local LLM API. Must be an API that implements the OpenAI Chat Completions API, but most do.
+LLM_SETTINGS__LOCAL_LLM_URL="http://localhost:1234/v1/chat/completions"
+
+# Name of the local LLM model to use.
+LLM_SETTINGS__LOCAL_LLM_MODEL="gpt-oss"
+
+# Number of non-speech chunks to wait before speech ended. A chunk is approximately 31 ms. Increasing this number allows longer pauses in speech, but also increases response time.
+BEHAVIOUR_SETTINGS__VAD_NON_SPEECH_PATIENCE_CHUNKS=3
+
+# Timeout in milliseconds for socket polling. Increase this number if network latency/jitter is high, often the case when using Wi-Fi. Perhaps 500 ms. A symptom of this issue is transcriptions getting cut off.
+BEHAVIOUR_SETTINGS__SOCKET_POLLER_TIMEOUT_MS=100
+
+
+
+# For an exhaustive list of options, see the control_backend.core.config module in the docs.

README.md

@@ -27,6 +27,7 @@ This + part might differ based on what model you choose.
 copy the model name in the module loaded and replace local_llm_modelL. In settings.
 
 
+
 ## Running
 To run the project (development server), execute the following command (while inside the root repository):
 
@@ -34,6 +35,14 @@ To run the project (development server), execute the following command (while in
 uv run fastapi dev src/control_backend/main.py
 ```
 
+### Environment Variables
+
+You can use environment variables to change settings. Make a copy of the [`.env.example`](.env.example) file, name it `.env` and put it in the root directory. The file itself describes how to do the configuration.
+
+For an exhaustive list of environment options, see the `control_backend.core.config` module in the docs.
+
+
+
 ## Testing
 Testing happens automatically when opening a merge request to any branch. If you want to manually run the test suite, you can do so by running the following for unit tests:
 

src/control_backend/agents/actuation/robot_speech_agent.py

@@ -29,7 +29,7 @@ class RobotSpeechAgent(BaseAgent):
     def __init__(
         self,
         name: str,
-        address=settings.zmq_settings.ri_command_address,
+        address: str,
         bind=False,
     ):
         super().__init__(name)

src/control_backend/agents/communication/ri_communication_agent.py

@@ -37,7 +37,7 @@ class RICommunicationAgent(BaseAgent):
     def __init__(
         self,
         name: str,
-        address=settings.zmq_settings.ri_command_address,
+        address=settings.zmq_settings.ri_communication_address,
         bind=False,
     ):
         super().__init__(name)

src/control_backend/agents/perception/vad_agent.py

@@ -166,9 +166,8 @@ class VADAgent(BaseAgent):
         """
         try:
             self.audio_out_socket = azmq.Context.instance().socket(zmq.PUB)
-            address = "inproc://vad_stream"
-            self.audio_out_socket.bind(address)
-            return address
+            self.audio_out_socket.bind(settings.zmq_settings.vad_pub_address)
+            return settings.zmq_settings.vad_pub_address
         except zmq.ZMQBindError:
             self.logger.error("Failed to bind an audio output socket after 100 tries.")
             self.audio_out_socket = None

src/control_backend/core/config.py

@@ -1,3 +1,12 @@
+"""
+An exhaustive overview of configurable options. All of these can be set using environment variables
+by nesting with double underscores (__). Start from the ``Settings`` class.
+
+For example, ``settings.ri_host`` becomes ``RI_HOST``, and
+``settings.zmq_settings.ri_communication_address`` becomes
+``ZMQ_SETTINGS__RI_COMMUNICATION_ADDRESS``.
+"""
+
 from pydantic import BaseModel
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
@@ -8,15 +17,16 @@ class ZMQSettings(BaseModel):
 
     :ivar internal_pub_address: Address for the internal PUB socket.
     :ivar internal_sub_address: Address for the internal SUB socket.
-    :ivar ri_command_address: Address for sending commands to the Robot Interface.
-    :ivar ri_communication_address: Address for receiving communication from the Robot Interface.
-    :ivar vad_agent_address: Address for the Voice Activity Detection (VAD) agent.
+    :ivar ri_communication_address: Address for the endpoint that the Robot Interface connects to.
+    :ivar vad_pub_address: Address that the VAD agent binds to and publishes audio segments to.
     """
 
+    # ATTENTION: When adding/removing settings, make sure to update the .env.example file
+
     internal_pub_address: str = "tcp://localhost:5560"
     internal_sub_address: str = "tcp://localhost:5561"
-    ri_command_address: str = "tcp://localhost:0000"
     ri_communication_address: str = "tcp://*:5555"
+    vad_pub_address: str = "inproc://vad_stream"
 
 
 class AgentSettings(BaseModel):
@@ -35,6 +45,8 @@ class AgentSettings(BaseModel):
     :ivar robot_speech_name: Name of the Robot Speech Agent.
     """
 
+    # ATTENTION: When adding/removing settings, make sure to update the .env.example file
+
     # agent names
     bdi_core_name: str = "bdi_core_agent"
     bdi_belief_collector_name: str = "belief_collector_agent"
@@ -64,6 +76,8 @@ class BehaviourSettings(BaseModel):
     :ivar transcription_token_buffer: Buffer for transcription tokens.
     """
 
+    # ATTENTION: When adding/removing settings, make sure to update the .env.example file
+
     sleep_s: float = 1.0
     comm_setup_max_retries: int = 5
     socket_poller_timeout_ms: int = 100
@@ -88,6 +102,8 @@ class LLMSettings(BaseModel):
     :ivar local_llm_model: Name of the local LLM model to use.
     """
 
+    # ATTENTION: When adding/removing settings, make sure to update the .env.example file
+
     local_llm_url: str = "http://localhost:1234/v1/chat/completions"
     local_llm_model: str = "gpt-oss"
 
@@ -101,6 +117,8 @@ class VADSettings(BaseModel):
     :ivar sample_rate_hz: Sample rate in Hz for the VAD model.
     """
 
+    # ATTENTION: When adding/removing settings, make sure to update the .env.example file
+
     repo_or_dir: str = "snakers4/silero-vad"
     model_name: str = "silero_vad"
     sample_rate_hz: int = 16000
@@ -114,6 +132,8 @@ class SpeechModelSettings(BaseModel):
     :ivar openai_model_name: Model name for OpenAI-based speech recognition.
     """
 
+    # ATTENTION: When adding/removing settings, make sure to update the .env.example file
+
     # model identifiers for speech recognition
     mlx_model_name: str = "mlx-community/whisper-small.en-mlx"
     openai_model_name: str = "small.en"
@@ -125,7 +145,7 @@ class Settings(BaseSettings):
 
     :ivar app_title: Title of the application.
     :ivar ui_url: URL of the frontend UI.
-    :ivar ui_url: The hostname of the Robot Interface.
+    :ivar ri_host: The hostname of the Robot Interface.
     :ivar zmq_settings: ZMQ configuration.
     :ivar agent_settings: Agent name configuration.
     :ivar behaviour_settings: Behavior configuration.

test/unit/agents/actuation/test_robot_speech_agent.py

@@ -56,7 +56,7 @@ async def test_setup_connect(zmq_context, mocker):
 async def test_handle_message_sends_command():
     """Internal message is forwarded to robot pub socket as JSON."""
     pubsocket = AsyncMock()
-    agent = RobotSpeechAgent("robot_speech")
+    agent = RobotSpeechAgent("robot_speech", "tcp://localhost:3498")
     agent.pubsocket = pubsocket
 
     payload = {"endpoint": "actuate/speech", "data": "hello"}
@@ -80,7 +80,7 @@ async def test_zmq_command_loop_valid_payload(zmq_context):
 
     fake_socket.recv_multipart = recv_once
     fake_socket.send_json = AsyncMock()
-    agent = RobotSpeechAgent("robot_speech")
+    agent = RobotSpeechAgent("robot_speech", "tcp://localhost:3498")
     agent.subsocket = fake_socket
     agent.pubsocket = fake_socket
     agent._running = True
@@ -101,7 +101,7 @@ async def test_zmq_command_loop_invalid_json():
 
     fake_socket.recv_multipart = recv_once
     fake_socket.send_json = AsyncMock()
-    agent = RobotSpeechAgent("robot_speech")
+    agent = RobotSpeechAgent("robot_speech", "tcp://localhost:3498")
     agent.subsocket = fake_socket
     agent.pubsocket = fake_socket
     agent._running = True
@@ -115,7 +115,7 @@ async def test_zmq_command_loop_invalid_json():
 async def test_handle_message_invalid_payload():
     """Invalid payload is caught and does not send."""
     pubsocket = AsyncMock()
-    agent = RobotSpeechAgent("robot_speech")
+    agent = RobotSpeechAgent("robot_speech", "tcp://localhost:3498")
     agent.pubsocket = pubsocket
 
     msg = InternalMessage(to="robot", sender="tester", body=json.dumps({"bad": "data"}))
@@ -129,7 +129,7 @@ async def test_handle_message_invalid_payload():
 async def test_stop_closes_sockets():
     pubsocket = MagicMock()
     subsocket = MagicMock()
-    agent = RobotSpeechAgent("robot_speech")
+    agent = RobotSpeechAgent("robot_speech", "tcp://localhost:3498")
     agent.pubsocket = pubsocket
     agent.subsocket = subsocket