examples(foundational): use system_instruction in all examples

examples/foundational/07zg-interruptible-camb.py

@@ -59,18 +59,12 @@ async def run_bot(transport: BaseTransport, runner_args: RunnerArguments):
         model="mars-flash",
     )
 
-    llm = OpenAILLMService(api_key=os.getenv("OPENAI_API_KEY"))
+    llm = OpenAILLMService(
+        api_key=os.getenv("OPENAI_API_KEY"),
+        system_instruction="You are a helpful voice assistant powered by Camb AI text-to-speech. ",
+    )
 
-    messages = [
-        {
-            "role": "system",
-            "content": "You are a helpful voice assistant powered by Camb AI text-to-speech. "
-            "Keep your responses concise and conversational since they will be spoken aloud. "
-            "Avoid special characters, emojis, or bullet points.",
-        },
-    ]
-
-    context = LLMContext(messages)
+    context = LLMContext()
     user_aggregator, assistant_aggregator = LLMContextAggregatorPair(
         context,
         user_params=LLMUserAggregatorParams(vad_analyzer=SileroVADAnalyzer()),
@@ -101,7 +95,7 @@ async def run_bot(transport: BaseTransport, runner_args: RunnerArguments):
     @transport.event_handler("on_client_connected")
     async def on_client_connected(transport, client):
         logger.info("Client connected")
-        messages.append({"role": "system", "content": "Please introduce yourself to the user."})
+        context.add_message({"role": "system", "content": "Please introduce yourself to the user."})
         await task.queue_frames([LLMRunFrame()])
 
     @transport.event_handler("on_client_disconnected")