♻️(agent) simplify Deepgram config and support Kyutai

The previous attempt to make the Deepgram configuration extensible
introduced unnecessary complexity for a very limited use case and
made it harder to add new STT backends.

Refactor to a deliberately simple and explicit design with minimal
cognitive overhead. Configuration is now fully driven by environment
variables and provides enough flexibility for ops to select and
parameterize the STT backend.

CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to
 
 ## [Unreleased]
 
+- ✨(agent) support Kyutai client for subtitle
+
 ## [1.1.0] - 2025-12-22
 
 ### Added 

src/agents/multi-user-transcriber.py

@@ -5,6 +5,7 @@ import logging
 import os
 
 from dotenv import load_dotenv
+from lasuite.plugins import kyutai
 from livekit import api, rtc
 from livekit.agents import (
     Agent,
@@ -28,60 +29,25 @@ load_dotenv()
 logger = logging.getLogger("transcriber")
 
 TRANSCRIBER_AGENT_NAME = os.getenv("TRANSCRIBER_AGENT_NAME", "multi-user-transcriber")
-
-# Default Deepgram STT configuration
-DEEPGRAM_STT_DEFAULTS = {
-    "model": "nova-3",
-    "language": "multi",
-}
-
-# Supported parameters for LiveKit's deepgram.STT() in streaming mode
-# Note: Not all Deepgram API parameters are supported by the LiveKit plugin
-# detect_language is NOT supported for real-time streaming
-# Use language="multi" instead for automatic multilingual support
-DEEPGRAM_STT_SUPPORTED_PARAMS = {
-    "model",
-    "language",
-}
+STT_PROVIDER = os.getenv("STT_PROVIDER", "deepgram")
 
 
-def _build_deepgram_stt_kwargs():
-    """Build Deepgram STT kwargs from DEEPGRAM_STT_* environment variables.
+def create_stt_provider():
+    """Create STT provider based on environment configuration."""
+    if STT_PROVIDER == "deepgram":
+        # Note: Not all Deepgram API parameters are supported by the LiveKit plugin
+        # detect_language is NOT supported for real-time streaming
+        # Use language="multi" instead for automatic multilingual support
+        _stt_instance = deepgram.STT(
+            model=os.getenv("DEEPGRAM_STT_MODEL", "nova-3"),
+            language=os.getenv("DEEPGRAM_STT_LANGUAGE", "multi"),
+        )
+    elif STT_PROVIDER == "kyutai":
+        _stt_instance = kyutai.STT(base_url=os.getenv("KYUTAI_STT_BASE_URL"))
+    else:
+        raise ValueError(f"Unknown STT_PROVIDER: {STT_PROVIDER}")
 
-    Only parameters supported by LiveKit's deepgram.STT() are included.
-    Unsupported parameters are logged as warnings.
-    """
-    stt_kwargs = DEEPGRAM_STT_DEFAULTS.copy()
-
-    # Scan environment variables for DEEPGRAM_STT_* pattern
-    for key, value in os.environ.items():
-        if key.startswith("DEEPGRAM_STT_"):
-            # Extract parameter name and convert to lowercase
-            param_name = key.replace("DEEPGRAM_STT_", "", 1).lower()
-
-            # Check if parameter is supported by LiveKit plugin
-            if param_name not in DEEPGRAM_STT_SUPPORTED_PARAMS:
-                supported = ", ".join(sorted(DEEPGRAM_STT_SUPPORTED_PARAMS))
-                logger.warning(
-                    f"Ignoring unsupported Deepgram STT parameter: {param_name}. "
-                    f"Supported parameters: {supported}"
-                )
-                continue
-
-            # Parse value type
-            value_lower = value.lower()
-            if value_lower in ("true", "false"):
-                # Boolean values
-                stt_kwargs[param_name] = value_lower == "true"
-            elif value.isdigit():
-                # Integer values
-                stt_kwargs[param_name] = int(value)
-            else:
-                # String values
-                stt_kwargs[param_name] = value
-
-    logger.info(f"Deepgram STT configuration: {stt_kwargs}")
-    return stt_kwargs
+    return _stt_instance
 
 
 class Transcriber(Agent):
@@ -89,12 +55,11 @@ class Transcriber(Agent):
 
     def __init__(self, *, participant_identity: str):
         """Init transcription agent."""
-        # Build STT configuration from environment variables
-        stt_kwargs = _build_deepgram_stt_kwargs()
+        stt = create_stt_provider()
 
         super().__init__(
             instructions="not-needed",
-            stt=deepgram.STT(**stt_kwargs),
+            stt=stt,
         )
         self.participant_identity = participant_identity