feat: limit transcription output length based on input

Using heuristics. Also adds documentation and initial unit tests.

ref: N25B-209

src/control_backend/agents/transcription/transcription_agent.py

@@ -35,18 +35,29 @@ class TranscriptionAgent(Agent):
             self.speech_recognizer = SpeechRecognizer.best_type()
             self._concurrency = asyncio.Semaphore(3)
 
+        def warmup(self):
+            """Load the transcription model into memory to speed up the first transcription."""
+            self.speech_recognizer.load_model()
+
         async def _transcribe(self, audio: np.ndarray) -> str:
             async with self._concurrency:
                 return await asyncio.to_thread(self.speech_recognizer.recognize_speech, audio)
 
+        async def _share_transcription(self, transcription: str):
+            """Share a transcription to the other agents that depend on it."""
+            receiver_jids = []  # Set message receivers here
+
+            for receiver_jid in receiver_jids:
+                message = Message(to=receiver_jid, body=transcription)
+                await self.send(message)
+
         async def run(self) -> None:
             audio = await self.audio_in_socket.recv()
             audio = np.frombuffer(audio, dtype=np.float32)
             speech = await self._transcribe(audio)
             logger.info("Transcribed speech: %s", speech)
 
-            message = Message(body=speech)
-            await self.send(message)
+            await self._share_transcription(speech)
 
     async def stop(self):
         self.audio_in_socket.close()
@@ -64,6 +75,7 @@ class TranscriptionAgent(Agent):
         self._connect_audio_in_socket()
 
         transcribing = self.Transcribing(self.audio_in_socket)
+        transcribing.warmup()
         self.add_behaviour(transcribing)
 
         logger.info("Finished setting up %s", self.jid)