AI-VideoAssistant/engine/core/duplex_pipeline.py

"""Full duplex audio pipeline for AI voice conversation.

This module implements the core duplex pipeline that orchestrates:
- VAD (Voice Activity Detection)
- EOU (End of Utterance) Detection
- ASR (Automatic Speech Recognition) - optional
- LLM (Language Model)
- TTS (Text-to-Speech)

Inspired by pipecat's frame-based architecture and active-call's
event-driven design.
"""

import asyncio
import audioop
import io
import json
import time
import uuid
import wave
from pathlib import Path
from typing import Any, Awaitable, Callable, Dict, List, Optional, Tuple

import numpy as np
import aiohttp
from loguru import logger

from app.config import settings
from app.service_factory import DefaultRealtimeServiceFactory
from core.conversation import ConversationManager, ConversationState
from core.events import get_event_bus
from core.ports import (
    ASRPort,
    ASRServiceSpec,
    LLMPort,
    LLMServiceSpec,
    RealtimeServiceFactory,
    TTSPort,
    TTSServiceSpec,
)
from core.tool_executor import execute_server_tool
from core.transports import BaseTransport
from models.ws_v1 import ev
from processors.eou import EouDetector
from processors.vad import SileroVAD, VADProcessor
from services.base import LLMMessage, LLMStreamEvent
from services.streaming_text import extract_tts_sentence, has_spoken_content


class DuplexPipeline:
    """
    Full duplex audio pipeline for AI voice conversation.

    Handles bidirectional audio flow with:
    - User speech detection and transcription
    - AI response generation
    - Text-to-speech synthesis
    - Barge-in (interruption) support

    Architecture (inspired by pipecat):

        User Audio → VAD → EOU → [ASR] → LLM → TTS → Audio Out
                      ↓
                  Barge-in Detection → Interrupt
    """

    _SENTENCE_END_CHARS = frozenset({"。", "！", "？", ".", "!", "?", "\n"})
    _SENTENCE_TRAILING_CHARS = frozenset({"。", "！", "？", ".", "!", "?", "…", "~", "～", "\n"})
    _SENTENCE_CLOSERS = frozenset({'"', "'", "”", "’", ")", "]", "}", "）", "】", "」", "』", "》"})
    _MIN_SPLIT_SPOKEN_CHARS = 6
    _TOOL_WAIT_TIMEOUT_SECONDS = 60.0
    _SERVER_TOOL_TIMEOUT_SECONDS = 15.0
    TRACK_AUDIO_IN = "audio_in"
    TRACK_AUDIO_OUT = "audio_out"
    TRACK_CONTROL = "control"
    _PCM_FRAME_BYTES = 640  # 16k mono pcm_s16le, 20ms
    _ASR_DELTA_THROTTLE_MS = 500
    _LLM_DELTA_THROTTLE_MS = 80
    _ASR_CAPTURE_MAX_MS = 15000
    _OPENER_PRE_ROLL_MS = 180
    _DEFAULT_TOOL_SCHEMAS: Dict[str, Dict[str, Any]] = {
        "current_time": {
            "name": "current_time",
            "description": "Get current local time",
            "parameters": {
                "type": "object",
                "properties": {},
                "required": [],
            },
        },
        "calculator": {
            "name": "calculator",
            "description": "Execute a math expression",
            "parameters": {
                "type": "object",
                "properties": {
                    "expression": {"type": "string", "description": "Math expression, e.g. 2 + 3 * 4"},
                },
                "required": ["expression"],
            },
        },
        "code_interpreter": {
            "name": "code_interpreter",
            "description": "Safely evaluate a Python expression",
            "parameters": {
                "type": "object",
                "properties": {
                    "code": {"type": "string", "description": "Python expression to evaluate"},
                },
                "required": ["code"],
            },
        },
        "turn_on_camera": {
            "name": "turn_on_camera",
            "description": "Turn on client camera",
            "parameters": {
                "type": "object",
                "properties": {},
                "required": [],
            },
        },
        "turn_off_camera": {
            "name": "turn_off_camera",
            "description": "Turn off client camera",
            "parameters": {
                "type": "object",
                "properties": {},
                "required": [],
            },
        },
        "increase_volume": {
            "name": "increase_volume",
            "description": "Increase client volume",
            "parameters": {
                "type": "object",
                "properties": {
                    "step": {"type": "integer", "description": "Volume increase step, default 1"},
                },
                "required": [],
            },
        },
        "decrease_volume": {
            "name": "decrease_volume",
            "description": "Decrease client volume",
            "parameters": {
                "type": "object",
                "properties": {
                    "step": {"type": "integer", "description": "Volume decrease step, default 1"},
                },
                "required": [],
            },
        },
        "voice_msg_prompt": {
            "name": "voice_msg_prompt",
            "description": "Speak a message prompt on client side",
            "parameters": {
                "type": "object",
                "properties": {
                    "msg": {"type": "string", "description": "Message text to speak"},
                },
                "required": ["msg"],
            },
        },
        "text_msg_prompt": {
            "name": "text_msg_prompt",
            "description": "Show a text message prompt dialog on client side",
            "parameters": {
                "type": "object",
                "properties": {
                    "msg": {"type": "string", "description": "Message text to display"},
                },
                "required": ["msg"],
            },
        },
        "voice_choice_prompt": {
            "name": "voice_choice_prompt",
            "description": "Speak a question and show options on client side, then wait for selection",
            "parameters": {
                "type": "object",
                "properties": {
                    "question": {"type": "string", "description": "Question text to show"},
                    "options": {
                        "type": "array",
                        "description": "Selectable options (string or object with id/label/value)",
                        "minItems": 2,
                        "items": {
                            "anyOf": [
                                {"type": "string"},
                                {
                                    "type": "object",
                                    "properties": {
                                        "id": {"type": "string"},
                                        "label": {"type": "string"},
                                        "value": {"type": "string"},
                                    },
                                    "required": ["label"],
                                },
                            ]
                        },
                    },
                    "voice_text": {
                        "type": "string",
                        "description": "Optional voice text. Falls back to question when omitted.",
                    },
                },
                "required": ["question", "options"],
            },
        },
        "text_choice_prompt": {
            "name": "text_choice_prompt",
            "description": "Show a text-only choice prompt on client side and wait for selection",
            "parameters": {
                "type": "object",
                "properties": {
                    "question": {"type": "string", "description": "Question text to show"},
                    "options": {
                        "type": "array",
                        "description": "Selectable options (string or object with id/label/value)",
                        "minItems": 2,
                        "items": {
                            "anyOf": [
                                {"type": "string"},
                                {
                                    "type": "object",
                                    "properties": {
                                        "id": {"type": "string"},
                                        "label": {"type": "string"},
                                        "value": {"type": "string"},
                                    },
                                    "required": ["label"],
                                },
                            ]
                        },
                    },
                },
                "required": ["question", "options"],
            },
        },
    }
    _DEFAULT_CLIENT_EXECUTORS = frozenset({
        "turn_on_camera",
        "turn_off_camera",
        "increase_volume",
        "decrease_volume",
        "voice_msg_prompt",
        "text_msg_prompt",
        "voice_choice_prompt",
        "text_choice_prompt",
    })
    _TOOL_NAME_ALIASES = {
        "voice_message_prompt": "voice_msg_prompt",
    }

    @classmethod
    def _normalize_tool_name(cls, raw_name: Any) -> str:
        name = str(raw_name or "").strip()
        if not name:
            return ""
        return cls._TOOL_NAME_ALIASES.get(name, name)

    def __init__(
        self,
        transport: BaseTransport,
        session_id: str,
        llm_service: Optional[LLMPort] = None,
        tts_service: Optional[TTSPort] = None,
        asr_service: Optional[ASRPort] = None,
        system_prompt: Optional[str] = None,
        greeting: Optional[str] = None,
        knowledge_searcher: Optional[
            Callable[..., Awaitable[List[Dict[str, Any]]]]
        ] = None,
        tool_resource_resolver: Optional[
            Callable[[str], Awaitable[Optional[Dict[str, Any]]]]
        ] = None,
        server_tool_executor: Optional[
            Callable[[Dict[str, Any]], Awaitable[Dict[str, Any]]]
        ] = None,
        service_factory: Optional[RealtimeServiceFactory] = None,
    ):
        """
        Initialize duplex pipeline.

        Args:
            transport: Transport for sending audio/events
            session_id: Session identifier
            llm_service: Optional injected LLM port implementation
            tts_service: Optional injected TTS port implementation
            asr_service: ASR service (optional)
            system_prompt: System prompt for LLM
            greeting: Optional greeting to speak on start
        """
        self.transport = transport
        self.session_id = session_id
        self.event_bus = get_event_bus()
        self.track_audio_in = self.TRACK_AUDIO_IN
        self.track_audio_out = self.TRACK_AUDIO_OUT
        self.track_control = self.TRACK_CONTROL

        # Initialize VAD
        self.vad_model = SileroVAD(
            model_path=settings.vad_model_path,
            sample_rate=settings.sample_rate
        )
        self.vad_processor = VADProcessor(
            vad_model=self.vad_model,
            threshold=settings.vad_threshold
        )

        # Initialize EOU detector
        self.eou_detector = EouDetector(
            silence_threshold_ms=settings.vad_eou_threshold_ms,
            min_speech_duration_ms=settings.vad_min_speech_duration_ms
        )

        # Initialize services
        self.llm_service = llm_service
        self.tts_service = tts_service
        self.asr_service = asr_service  # Will be initialized in start()
        self._service_factory = service_factory or DefaultRealtimeServiceFactory()
        self._knowledge_searcher = knowledge_searcher
        self._tool_resource_resolver = tool_resource_resolver
        self._server_tool_executor = server_tool_executor

        # Track last sent transcript to avoid duplicates
        self._last_sent_transcript = ""
        self._pending_transcript_delta: str = ""
        self._last_transcript_delta_emit_ms: float = 0.0

        # Conversation manager
        self.conversation = ConversationManager(
            system_prompt=system_prompt,
            greeting=greeting
        )

        # State
        self._running = True
        self._is_bot_speaking = False
        self._current_turn_task: Optional[asyncio.Task] = None
        self._audio_buffer: bytes = b""
        max_buffer_seconds = settings.max_audio_buffer_seconds
        self._max_audio_buffer_bytes = int(settings.sample_rate * 2 * max_buffer_seconds)
        self._asr_start_min_speech_ms: int = settings.asr_start_min_speech_ms
        self._asr_capture_active: bool = False
        self._asr_capture_started_ms: float = 0.0
        self._pending_speech_audio: bytes = b""
        # Keep a short rolling pre-speech window so VAD transition latency
        # does not clip the first phoneme/character sent to ASR.
        pre_speech_ms = settings.asr_pre_speech_ms
        self._asr_pre_speech_bytes = int(settings.sample_rate * 2 * (pre_speech_ms / 1000.0))
        self._pre_speech_buffer: bytes = b""
        # Add a tiny trailing silence tail before final ASR to avoid
        # clipping the last phoneme at utterance boundaries.
        asr_final_tail_ms = settings.asr_final_tail_ms
        self._asr_final_tail_bytes = int(settings.sample_rate * 2 * (asr_final_tail_ms / 1000.0))
        self._last_vad_status: str = "Silence"
        self._process_lock = asyncio.Lock()
        # Priority outbound dispatcher (lower value = higher priority).
        self._outbound_q: asyncio.PriorityQueue[Tuple[int, int, str, Any]] = asyncio.PriorityQueue()
        self._outbound_seq = 0
        self._outbound_task: Optional[asyncio.Task] = None
        self._drop_outbound_audio = False
        self._audio_out_frame_buffer: bytes = b""

        # Interruption handling
        self._interrupt_event = asyncio.Event()

        # Latency tracking - TTFB (Time to First Byte)
        self._turn_start_time: Optional[float] = None
        self._first_audio_sent: bool = False

        # Barge-in filtering - require minimum speech duration to interrupt
        self._barge_in_speech_start_time: Optional[float] = None
        self._barge_in_min_duration_ms: int = settings.barge_in_min_duration_ms
        self._barge_in_silence_tolerance_ms: int = settings.barge_in_silence_tolerance_ms
        self._barge_in_speech_frames: int = 0  # Count speech frames
        self._barge_in_silence_frames: int = 0  # Count silence frames during potential barge-in

        # Runtime overrides injected from session.start metadata
        self._runtime_llm: Dict[str, Any] = {}
        self._runtime_asr: Dict[str, Any] = {}
        self._runtime_tts: Dict[str, Any] = {}
        self._runtime_output: Dict[str, Any] = {}
        self._runtime_system_prompt: Optional[str] = None
        self._runtime_first_turn_mode: str = "bot_first"
        self._runtime_greeting: Optional[str] = None
        self._runtime_generated_opener_enabled: Optional[bool] = None
        self._runtime_manual_opener_tool_calls: List[Any] = []
        self._runtime_opener_audio: Dict[str, Any] = {}
        self._runtime_barge_in_enabled: Optional[bool] = None
        self._runtime_barge_in_min_duration_ms: Optional[int] = None
        self._runtime_knowledge: Dict[str, Any] = {}
        self._runtime_knowledge_base_id: Optional[str] = None
        raw_default_tools = settings.tools if isinstance(settings.tools, list) else []
        self._runtime_tools: List[Any] = list(raw_default_tools)
        self._runtime_tool_executor: Dict[str, str] = {}
        self._runtime_tool_default_args: Dict[str, Dict[str, Any]] = {}
        self._runtime_tool_id_map: Dict[str, str] = {}
        self._runtime_tool_display_names: Dict[str, str] = {}
        self._runtime_tool_wait_for_response: Dict[str, bool] = {}
        self._pending_tool_waiters: Dict[str, asyncio.Future] = {}
        self._early_tool_results: Dict[str, Dict[str, Any]] = {}
        self._completed_tool_call_ids: set[str] = set()
        self._pending_client_tool_call_ids: set[str] = set()
        self._pending_client_playback_tts_ids: set[str] = set()
        self._tts_playback_context: Dict[str, Dict[str, Optional[str]]] = {}
        self._last_client_played_tts_id: Optional[str] = None
        self._last_client_played_response_id: Optional[str] = None
        self._last_client_played_turn_id: Optional[str] = None
        self._last_client_played_at_ms: Optional[int] = None
        self._next_seq: Optional[Callable[[], int]] = None
        self._local_seq: int = 0

        # Cross-service correlation IDs
        self._turn_count: int = 0
        self._response_count: int = 0
        self._tts_count: int = 0
        self._utterance_count: int = 0
        self._current_turn_id: Optional[str] = None
        self._current_utterance_id: Optional[str] = None
        self._current_response_id: Optional[str] = None
        self._current_tts_id: Optional[str] = None
        self._pending_llm_delta: str = ""
        self._last_llm_delta_emit_ms: float = 0.0

        self._runtime_tool_executor = self._resolved_tool_executor_map()
        self._runtime_tool_default_args = self._resolved_tool_default_args_map()
        self._runtime_tool_id_map = self._resolved_tool_id_map()
        self._runtime_tool_display_names = self._resolved_tool_display_name_map()
        self._runtime_tool_wait_for_response = self._resolved_tool_wait_for_response_map()
        self._initial_greeting_emitted = False

        if self._server_tool_executor is None:
            if self._tool_resource_resolver:
                async def _executor(call: Dict[str, Any]) -> Dict[str, Any]:
                    return await execute_server_tool(
                        call,
                        tool_resource_fetcher=self._tool_resource_resolver,
                    )

                self._server_tool_executor = _executor
            else:
                self._server_tool_executor = execute_server_tool

        logger.info(f"DuplexPipeline initialized for session {session_id}")

    def set_event_sequence_provider(self, provider: Callable[[], int]) -> None:
        """Use session-scoped monotonic sequence provider for envelope events."""
        self._next_seq = provider

    def apply_runtime_overrides(self, metadata: Optional[Dict[str, Any]]) -> None:
        """
        Apply runtime overrides from WS session.start metadata.

        Expected metadata shape:
        {
            "systemPrompt": "...",
            "greeting": "...",
            "services": {
                "llm": {...},
                "asr": {...},
                "tts": {...}
            }
        }
        """
        if not metadata:
            return

        if "systemPrompt" in metadata:
            self._runtime_system_prompt = str(metadata.get("systemPrompt") or "")
            if self._runtime_system_prompt:
                self.conversation.system_prompt = self._runtime_system_prompt
        if "firstTurnMode" in metadata:
            raw_mode = str(metadata.get("firstTurnMode") or "").strip().lower()
            self._runtime_first_turn_mode = "user_first" if raw_mode == "user_first" else "bot_first"
        if "greeting" in metadata:
            greeting_payload = metadata.get("greeting")
            if isinstance(greeting_payload, dict):
                self._runtime_greeting = str(greeting_payload.get("text") or "")
                generated_flag = self._coerce_bool(greeting_payload.get("generated"))
                if generated_flag is not None:
                    self._runtime_generated_opener_enabled = generated_flag
            else:
                self._runtime_greeting = str(greeting_payload or "")
            self.conversation.greeting = self._runtime_greeting or None
        generated_opener_flag = self._coerce_bool(metadata.get("generatedOpenerEnabled"))
        if generated_opener_flag is not None:
            self._runtime_generated_opener_enabled = generated_opener_flag
        if "manualOpenerToolCalls" in metadata:
            manual_calls = metadata.get("manualOpenerToolCalls")
            self._runtime_manual_opener_tool_calls = manual_calls if isinstance(manual_calls, list) else []

        services = metadata.get("services") or {}
        if isinstance(services, dict):
            if isinstance(services.get("llm"), dict):
                self._runtime_llm = services["llm"]
            if isinstance(services.get("asr"), dict):
                self._runtime_asr = services["asr"]
            if isinstance(services.get("tts"), dict):
                self._runtime_tts = services["tts"]
        output = metadata.get("output") or {}
        if isinstance(output, dict):
            self._runtime_output = output
        barge_in = metadata.get("bargeIn")
        if isinstance(barge_in, dict):
            barge_in_enabled = self._coerce_bool(barge_in.get("enabled"))
            if barge_in_enabled is not None:
                self._runtime_barge_in_enabled = barge_in_enabled
            min_duration = barge_in.get("minDurationMs")
            if isinstance(min_duration, (int, float, str)):
                try:
                    self._runtime_barge_in_min_duration_ms = max(0, int(min_duration))
                except (TypeError, ValueError):
                    self._runtime_barge_in_min_duration_ms = None

        knowledge_base_id = metadata.get("knowledgeBaseId")
        if knowledge_base_id is not None:
            kb_id = str(knowledge_base_id).strip()
            self._runtime_knowledge_base_id = kb_id or None

        knowledge = metadata.get("knowledge")
        if isinstance(knowledge, dict):
            self._runtime_knowledge = knowledge
        opener_audio = metadata.get("openerAudio")
        if isinstance(opener_audio, dict):
            self._runtime_opener_audio = dict(opener_audio)
            kb_id = str(knowledge.get("kbId") or knowledge.get("knowledgeBaseId") or "").strip()
            if kb_id:
                self._runtime_knowledge_base_id = kb_id

        tools_payload = metadata.get("tools")
        if isinstance(tools_payload, list):
            self._runtime_tools = tools_payload
            self._runtime_tool_executor = self._resolved_tool_executor_map()
            self._runtime_tool_default_args = self._resolved_tool_default_args_map()
            self._runtime_tool_id_map = self._resolved_tool_id_map()
            self._runtime_tool_display_names = self._resolved_tool_display_name_map()
            self._runtime_tool_wait_for_response = self._resolved_tool_wait_for_response_map()
        elif "tools" in metadata:
            self._runtime_tools = []
            self._runtime_tool_executor = {}
            self._runtime_tool_default_args = {}
            self._runtime_tool_id_map = {}
            self._runtime_tool_display_names = {}
            self._runtime_tool_wait_for_response = {}

        if self.llm_service and hasattr(self.llm_service, "set_knowledge_config"):
            self.llm_service.set_knowledge_config(self._resolved_knowledge_config())
        if self.llm_service and hasattr(self.llm_service, "set_tool_schemas"):
            self.llm_service.set_tool_schemas(self._resolved_tool_schemas())

    def resolved_runtime_config(self) -> Dict[str, Any]:
        """Return current effective runtime configuration without secrets."""
        llm_provider = str(self._runtime_llm.get("provider") or settings.llm_provider).lower()
        llm_base_url = (
            self._runtime_llm.get("baseUrl")
            or settings.llm_api_url
            or self._default_llm_base_url(llm_provider)
        )
        tts_provider = str(self._runtime_tts.get("provider") or settings.tts_provider).lower()
        asr_provider = str(self._runtime_asr.get("provider") or settings.asr_provider).lower()
        output_mode = str(self._runtime_output.get("mode") or "").strip().lower()
        if not output_mode:
            output_mode = "audio" if self._tts_output_enabled() else "text"

        tts_model = str(
            self._runtime_tts.get("model")
            or settings.tts_model
            or (self._default_dashscope_tts_model() if self._is_dashscope_tts_provider(tts_provider) else "")
        )
        tts_config = {
            "enabled": self._tts_output_enabled(),
            "provider": tts_provider,
            "model": tts_model,
            "voice": str(self._runtime_tts.get("voice") or settings.tts_voice),
            "speed": float(self._runtime_tts.get("speed") or settings.tts_speed),
        }
        if self._is_dashscope_tts_provider(tts_provider):
            tts_config["mode"] = self._resolved_dashscope_tts_mode()

        return {
            "output": {"mode": output_mode},
            "services": {
                "llm": {
                    "provider": llm_provider,
                    "model": str(self._runtime_llm.get("model") or settings.llm_model),
                    "baseUrl": llm_base_url,
                },
                "asr": {
                    "provider": asr_provider,
                    "model": str(self._runtime_asr.get("model") or settings.asr_model or ""),
                    "interimIntervalMs": int(self._runtime_asr.get("interimIntervalMs") or settings.asr_interim_interval_ms),
                    "minAudioMs": int(self._runtime_asr.get("minAudioMs") or settings.asr_min_audio_ms),
                },
                "tts": tts_config,
            },
            "tools": {
                "allowlist": self._resolved_tool_allowlist(),
            },
            "opener": {
                "generated": self._generated_opener_enabled(),
                "manualToolCallCount": len(self._resolved_manual_opener_tool_calls()),
            },
            "tracks": {
                "audio_in": self.track_audio_in,
                "audio_out": self.track_audio_out,
                "control": self.track_control,
            },
        }

    def _next_event_seq(self) -> int:
        if self._next_seq:
            return self._next_seq()
        self._local_seq += 1
        return self._local_seq

    def _event_source(self, event_type: str) -> str:
        if event_type.startswith("transcript.") or event_type.startswith("input.speech_"):
            return "asr"
        if event_type.startswith("assistant.response."):
            return "llm"
        if event_type.startswith("assistant.tool_"):
            return "tool"
        if event_type.startswith("output.audio.") or event_type == "metrics.ttfb":
            return "tts"
        return "system"

    def _new_id(self, prefix: str, counter: int) -> str:
        return f"{prefix}_{counter}_{uuid.uuid4().hex[:8]}"

    def _start_turn(self) -> str:
        self._turn_count += 1
        self._current_turn_id = self._new_id("turn", self._turn_count)
        self._current_utterance_id = None
        self._current_response_id = None
        self._current_tts_id = None
        return self._current_turn_id

    def _start_response(self) -> str:
        self._response_count += 1
        self._current_response_id = self._new_id("resp", self._response_count)
        self._current_tts_id = None
        return self._current_response_id

    def _start_tts(self) -> str:
        self._tts_count += 1
        tts_id = self._new_id("tts", self._tts_count)
        self._current_tts_id = tts_id
        self._tts_playback_context[tts_id] = {
            "turn_id": self._current_turn_id,
            "response_id": self._current_response_id,
        }
        return tts_id

    def _finalize_utterance(self) -> str:
        if self._current_utterance_id:
            return self._current_utterance_id
        self._utterance_count += 1
        self._current_utterance_id = self._new_id("utt", self._utterance_count)
        if not self._current_turn_id:
            self._start_turn()
        return self._current_utterance_id

    def _mark_client_playback_started(self, tts_id: Optional[str]) -> None:
        normalized_tts_id = str(tts_id or "").strip()
        if not normalized_tts_id:
            return
        self._pending_client_playback_tts_ids.add(normalized_tts_id)

    def _clear_client_playback_tracking(self) -> None:
        self._pending_client_playback_tts_ids.clear()
        self._tts_playback_context.clear()

    async def handle_output_audio_played(
        self,
        *,
        tts_id: str,
        response_id: Optional[str] = None,
        turn_id: Optional[str] = None,
        played_at_ms: Optional[int] = None,
        played_ms: Optional[int] = None,
    ) -> None:
        """Record client-side playback completion for a TTS segment."""
        normalized_tts_id = str(tts_id or "").strip()
        if not normalized_tts_id:
            return

        was_pending = normalized_tts_id in self._pending_client_playback_tts_ids
        self._pending_client_playback_tts_ids.discard(normalized_tts_id)

        context = self._tts_playback_context.pop(normalized_tts_id, {})
        resolved_response_id = str(response_id or context.get("response_id") or "").strip() or None
        resolved_turn_id = str(turn_id or context.get("turn_id") or "").strip() or None

        self._last_client_played_tts_id = normalized_tts_id
        self._last_client_played_response_id = resolved_response_id
        self._last_client_played_turn_id = resolved_turn_id
        if isinstance(played_at_ms, int) and played_at_ms >= 0:
            self._last_client_played_at_ms = played_at_ms
        else:
            self._last_client_played_at_ms = self._get_timestamp_ms()

        duration_ms = played_ms if isinstance(played_ms, int) and played_ms >= 0 else None
        logger.info(
            f"[PlaybackAck] tts_id={normalized_tts_id} response_id={resolved_response_id or '-'} "
            f"turn_id={resolved_turn_id or '-'} pending_before={was_pending} "
            f"pending_now={len(self._pending_client_playback_tts_ids)} "
            f"played_ms={duration_ms if duration_ms is not None else '-'}"
        )

    def _envelope_event(self, event: Dict[str, Any]) -> Dict[str, Any]:
        event_type = str(event.get("type") or "")
        source = str(event.get("source") or self._event_source(event_type))
        track_id = event.get("trackId")
        if not track_id:
            if source == "asr":
                track_id = self.track_audio_in
            elif source in {"llm", "tts", "tool"}:
                track_id = self.track_audio_out
            else:
                track_id = self.track_control

        data = event.get("data")
        if not isinstance(data, dict):
            data = {}
        explicit_turn_id = str(event.get("turn_id") or "").strip() or None
        explicit_utterance_id = str(event.get("utterance_id") or "").strip() or None
        explicit_response_id = str(event.get("response_id") or "").strip() or None
        explicit_tts_id = str(event.get("tts_id") or "").strip() or None
        if self._current_turn_id:
            data.setdefault("turn_id", self._current_turn_id)
        if self._current_utterance_id:
            data.setdefault("utterance_id", self._current_utterance_id)
        if self._current_response_id:
            data.setdefault("response_id", self._current_response_id)
        if self._current_tts_id:
            data.setdefault("tts_id", self._current_tts_id)
        if explicit_turn_id:
            data["turn_id"] = explicit_turn_id
        if explicit_utterance_id:
            data["utterance_id"] = explicit_utterance_id
        if explicit_response_id:
            data["response_id"] = explicit_response_id
        if explicit_tts_id:
            data["tts_id"] = explicit_tts_id

        for k, v in event.items():
            if k in {
                "type",
                "timestamp",
                "sessionId",
                "seq",
                "source",
                "trackId",
                "data",
                "turn_id",
                "utterance_id",
                "response_id",
                "tts_id",
            }:
                continue
            data.setdefault(k, v)

        event["sessionId"] = self.session_id
        event["seq"] = self._next_event_seq()
        event["source"] = source
        event["trackId"] = track_id
        event["data"] = data
        return event

    @staticmethod
    def _coerce_bool(value: Any) -> Optional[bool]:
        if isinstance(value, bool):
            return value
        if isinstance(value, (int, float)):
            return bool(value)
        if isinstance(value, str):
            normalized = value.strip().lower()
            if normalized in {"1", "true", "yes", "on", "enabled"}:
                return True
            if normalized in {"0", "false", "no", "off", "disabled"}:
                return False
        return None

    @staticmethod
    def _is_dashscope_tts_provider(provider: Any) -> bool:
        normalized = str(provider or "").strip().lower()
        return normalized == "dashscope"

    @staticmethod
    def _default_llm_base_url(provider: Any) -> Optional[str]:
        normalized = str(provider or "").strip().lower()
        if normalized == "siliconflow":
            return "https://api.siliconflow.cn/v1"
        return None

    @staticmethod
    def _default_dashscope_tts_model() -> str:
        return "qwen3-tts-flash-realtime"

    def _resolved_dashscope_tts_mode(self) -> str:
        raw_mode = str(self._runtime_tts.get("mode") or settings.tts_mode or "commit").strip().lower()
        if raw_mode in {"commit", "server_commit"}:
            return raw_mode
        return "commit"

    def _use_engine_sentence_split_for_tts(self) -> bool:
        tts_provider = str(self._runtime_tts.get("provider") or settings.tts_provider).strip().lower()
        if not self._is_dashscope_tts_provider(tts_provider):
            return True
        # DashScope commit mode is client-driven and expects engine-side segmentation.
        # server_commit mode lets DashScope handle segmentation on appended text.
        return self._resolved_dashscope_tts_mode() != "server_commit"

    def _tts_output_enabled(self) -> bool:
        enabled = self._coerce_bool(self._runtime_tts.get("enabled"))
        if enabled is not None:
            return enabled

        output_mode = str(self._runtime_output.get("mode") or "").strip().lower()
        if output_mode in {"text", "text_only", "text-only"}:
            return False

        return True

    def _generated_opener_enabled(self) -> bool:
        return self._runtime_generated_opener_enabled is True

    def _bot_starts_first(self) -> bool:
        return self._runtime_first_turn_mode != "user_first"

    def _barge_in_enabled(self) -> bool:
        if self._runtime_barge_in_enabled is not None:
            return self._runtime_barge_in_enabled
        return True

    def _resolved_barge_in_min_duration_ms(self) -> int:
        if self._runtime_barge_in_min_duration_ms is not None:
            return self._runtime_barge_in_min_duration_ms
        return self._barge_in_min_duration_ms

    def _barge_in_silence_tolerance_frames(self) -> int:
        """Convert silence tolerance from ms to frame count using current chunk size."""
        chunk_ms = max(1, settings.chunk_size_ms)
        return max(1, int(np.ceil(self._barge_in_silence_tolerance_ms / chunk_ms)))

    async def _generate_runtime_greeting(self) -> Optional[str]:
        if not self.llm_service:
            return None

        system_context = (self.conversation.system_prompt or self._runtime_system_prompt or "").strip()
        # Keep context concise to avoid overloading greeting generation.
        if len(system_context) > 1200:
            system_context = system_context[:1200]
        system_prompt = (
            "你是语音通话助手的开场白生成器。"
            "请只输出一句自然、简洁、友好的中文开场白。"
            "不要使用引号，不要使用 markdown，不要加解释。"
        )
        user_prompt = "请生成一句中文开场白（不超过25个汉字）。"
        if system_context:
            user_prompt += f"\n\n以下是该助手的系统提示词，请据此决定语气、角色和边界：\n{system_context}"

        try:
            generated = await self.llm_service.generate(
                [
                    LLMMessage(role="system", content=system_prompt),
                    LLMMessage(role="user", content=user_prompt),
                ],
                temperature=0.7,
                max_tokens=64,
            )
        except Exception as exc:
            logger.warning(f"Failed to generate runtime greeting: {exc}")
            return None

        text = (generated or "").strip()
        if not text:
            return None
        return text.strip().strip('"').strip("'")

    async def start(self) -> None:
        """Start the pipeline and connect services."""
        try:
            # Connect LLM service
            if not self.llm_service:
                llm_provider = (self._runtime_llm.get("provider") or settings.llm_provider).lower()
                llm_api_key = self._runtime_llm.get("apiKey")
                llm_base_url = (
                    self._runtime_llm.get("baseUrl")
                    or settings.llm_api_url
                    or self._default_llm_base_url(llm_provider)
                )
                llm_model = self._runtime_llm.get("model") or settings.llm_model
                self.llm_service = self._service_factory.create_llm_service(
                    LLMServiceSpec(
                        provider=llm_provider,
                        model=str(llm_model),
                        api_key=str(llm_api_key).strip() if llm_api_key else None,
                        base_url=str(llm_base_url).strip() if llm_base_url else None,
                        system_prompt=self.conversation.system_prompt,
                        temperature=settings.llm_temperature,
                        knowledge_config=self._resolved_knowledge_config(),
                        knowledge_searcher=self._knowledge_searcher,
                    )
                )

            if hasattr(self.llm_service, "set_knowledge_config"):
                self.llm_service.set_knowledge_config(self._resolved_knowledge_config())
            if hasattr(self.llm_service, "set_tool_schemas"):
                self.llm_service.set_tool_schemas(self._resolved_tool_schemas())

            await self.llm_service.connect()

            tts_output_enabled = self._tts_output_enabled()

            # Connect TTS service only when audio output is enabled.
            if tts_output_enabled:
                if not self.tts_service:
                    tts_provider = (self._runtime_tts.get("provider") or settings.tts_provider).lower()
                    tts_api_key = self._runtime_tts.get("apiKey")
                    tts_api_url = self._runtime_tts.get("baseUrl") or settings.tts_api_url
                    tts_voice = self._runtime_tts.get("voice") or settings.tts_voice
                    tts_model = self._runtime_tts.get("model") or settings.tts_model
                    tts_speed = float(self._runtime_tts.get("speed") or settings.tts_speed)
                    tts_mode = self._resolved_dashscope_tts_mode()
                    runtime_mode = str(self._runtime_tts.get("mode") or "").strip()
                    if runtime_mode and not self._is_dashscope_tts_provider(tts_provider):
                        logger.warning(
                            "services.tts.mode is DashScope-only and will be ignored "
                            f"for provider={tts_provider}"
                        )
                    self.tts_service = self._service_factory.create_tts_service(
                        TTSServiceSpec(
                            provider=tts_provider,
                            api_key=str(tts_api_key).strip() if tts_api_key else None,
                            api_url=str(tts_api_url).strip() if tts_api_url else None,
                            voice=str(tts_voice),
                            model=str(tts_model).strip() if tts_model else None,
                            sample_rate=settings.sample_rate,
                            speed=tts_speed,
                            mode=str(tts_mode),
                        )
                    )

                try:
                    await self.tts_service.connect()
                except Exception as e:
                    logger.warning(f"TTS backend unavailable ({e}); falling back to default TTS adapter")
                    self.tts_service = self._service_factory.create_tts_service(
                        TTSServiceSpec(
                            provider="mock",
                            voice="mock",
                            sample_rate=settings.sample_rate,
                        )
                    )
                    await self.tts_service.connect()
            else:
                self.tts_service = None
                logger.info("TTS output disabled by runtime metadata")

            # Connect ASR service
            if not self.asr_service:
                asr_provider = (self._runtime_asr.get("provider") or settings.asr_provider).lower()
                asr_api_key = self._runtime_asr.get("apiKey")
                asr_api_url = self._runtime_asr.get("baseUrl") or settings.asr_api_url
                asr_model = self._runtime_asr.get("model") or settings.asr_model
                asr_interim_interval = int(self._runtime_asr.get("interimIntervalMs") or settings.asr_interim_interval_ms)
                asr_min_audio_ms = int(self._runtime_asr.get("minAudioMs") or settings.asr_min_audio_ms)

                self.asr_service = self._service_factory.create_asr_service(
                    ASRServiceSpec(
                        provider=asr_provider,
                        sample_rate=settings.sample_rate,
                        language="auto",
                        api_key=str(asr_api_key).strip() if asr_api_key else None,
                        api_url=str(asr_api_url).strip() if asr_api_url else None,
                        model=str(asr_model).strip() if asr_model else None,
                        interim_interval_ms=asr_interim_interval,
                        min_audio_for_interim_ms=asr_min_audio_ms,
                        on_transcript=self._on_transcript_callback,
                    )
                )

            await self.asr_service.connect()

            logger.info("DuplexPipeline services connected")
            if not self._outbound_task or self._outbound_task.done():
                self._outbound_task = asyncio.create_task(self._outbound_loop())

        except Exception as e:
            logger.error(f"Failed to start pipeline: {e}")
            raise

    async def emit_initial_greeting(self) -> None:
        """
        Emit opener after session activation.

        Ordering target:
        1) frontend receives `session.started` (shows connected/ready)
        2) frontend receives opener text event
        3) frontend receives opener audio events/chunks
        """
        if self._initial_greeting_emitted:
            return

        self._initial_greeting_emitted = True
        if not self._bot_starts_first():
            return

        if self._generated_opener_enabled() and self._resolved_tool_schemas():
            # Run generated opener as a normal tool-capable assistant turn.
            # Use an empty user input so the opener can be driven by system prompt policy.
            if self._current_turn_task and not self._current_turn_task.done():
                logger.info("Skip initial generated opener: assistant turn already in progress")
                return
            self._current_turn_task = asyncio.create_task(self._handle_turn(""))
            logger.info("Initial generated opener started with tool-calling path")
            return

        manual_opener_execution: Dict[str, List[Dict[str, Any]]] = {"toolCalls": [], "toolResults": []}
        if not self._generated_opener_enabled() and self._resolved_manual_opener_tool_calls():
            self._start_turn()
            self._start_response()
            manual_opener_execution = await self._execute_manual_opener_tool_calls()

        greeting_to_speak = self.conversation.greeting
        if self._generated_opener_enabled():
            generated_greeting = await self._generate_runtime_greeting()
            if generated_greeting:
                greeting_to_speak = generated_greeting
                self.conversation.greeting = generated_greeting

        if not greeting_to_speak:
            if (
                not self._generated_opener_enabled()
                and manual_opener_execution.get("toolCalls")
                and not (self._current_turn_task and not self._current_turn_task.done())
            ):
                follow_up_context = self._build_manual_opener_follow_up_context(manual_opener_execution)
                self._current_turn_task = asyncio.create_task(
                    self._handle_turn("", system_context=follow_up_context)
                )
                logger.info("Initial manual opener follow-up started")
            return

        if not self._current_turn_id:
            self._start_turn()
        if not self._current_response_id:
            self._start_response()
        await self._send_event(
            ev(
                "assistant.response.final",
                text=greeting_to_speak,
                trackId=self.track_audio_out,
            ),
            priority=20,
        )
        await self.conversation.add_assistant_turn(greeting_to_speak)

        # Give client mic capture a short head start so opener can be interrupted immediately.
        await asyncio.sleep(self._OPENER_PRE_ROLL_MS / 1000.0)

        used_preloaded_audio = await self._play_preloaded_opener_audio()
        if self._tts_output_enabled() and not used_preloaded_audio:
            # Keep opener text ahead of opener voice start.
            await self._speak(greeting_to_speak, audio_event_priority=30)

    async def _play_preloaded_opener_audio(self) -> bool:
        """
        Play opener audio from runtime metadata cache or YAML-configured local file.

        Returns True when preloaded audio is played successfully.
        """
        if not self._tts_output_enabled():
            return False

        pcm_bytes = await self._load_preloaded_opener_pcm()
        if not pcm_bytes:
            return False

        try:
            self._drop_outbound_audio = False
            tts_id = self._start_tts()
            self._mark_client_playback_started(tts_id)
            await self._send_event(
                {
                    **ev(
                        "output.audio.start",
                        trackId=self.track_audio_out,
                    )
                },
                priority=30,
            )

            self._is_bot_speaking = True
            await self._send_audio(pcm_bytes, priority=50)
            await self._flush_audio_out_frames(priority=50)
            await self._send_event(
                {
                    **ev(
                        "output.audio.end",
                        trackId=self.track_audio_out,
                    )
                },
                priority=30,
            )
            return True
        except Exception as e:
            logger.warning(f"Failed to play preloaded opener audio, fallback to TTS: {e}")
            return False
        finally:
            self._is_bot_speaking = False

    async def _load_preloaded_opener_pcm(self) -> Optional[bytes]:
        # 1) Runtime metadata from backend config
        opener_audio = self._runtime_opener_audio if isinstance(self._runtime_opener_audio, dict) else {}
        if bool(opener_audio.get("enabled")) and bool(opener_audio.get("ready")):
            pcm_url = str(opener_audio.get("pcmUrl") or "").strip()
            if pcm_url:
                resolved_url = pcm_url
                if pcm_url.startswith("/"):
                    backend_url = str(settings.backend_url or "").strip().rstrip("/")
                    if backend_url:
                        resolved_url = f"{backend_url}{pcm_url}"
                try:
                    timeout = aiohttp.ClientTimeout(total=10)
                    async with aiohttp.ClientSession(timeout=timeout) as session:
                        async with session.get(resolved_url) as resp:
                            resp.raise_for_status()
                            payload = await resp.read()
                            if payload:
                                return payload
                except Exception as e:
                    logger.warning(f"Failed to fetch opener audio from backend ({resolved_url}): {e}")

        # 2) Standalone fallback via YAML
        opener_audio_file = str(settings.duplex_opener_audio_file or "").strip()
        if not opener_audio_file:
            return None
        path = Path(opener_audio_file)
        if not path.is_absolute():
            path = (Path.cwd() / path).resolve()
        if not path.exists() or not path.is_file():
            logger.warning(f"Configured opener audio file does not exist: {path}")
            return None
        try:
            raw = path.read_bytes()
            suffix = path.suffix.lower()
            if suffix == ".wav":
                pcm, _ = self._wav_to_pcm16_mono_16k(raw)
                return pcm
            # .pcm raw pcm_s16le 16k mono
            return raw
        except Exception as e:
            logger.warning(f"Failed to read opener audio file {path}: {e}")
            return None

    def _wav_to_pcm16_mono_16k(self, wav_bytes: bytes) -> Tuple[bytes, int]:
        with wave.open(io.BytesIO(wav_bytes), "rb") as wav_file:
            channels = wav_file.getnchannels()
            sample_width = wav_file.getsampwidth()
            sample_rate = wav_file.getframerate()
            nframes = wav_file.getnframes()
            raw = wav_file.readframes(nframes)

        if sample_width != 2:
            raise ValueError(f"Unsupported WAV sample width: {sample_width * 8}bit")
        if channels > 1:
            raw = audioop.tomono(raw, sample_width, 0.5, 0.5)
        if sample_rate != 16000:
            raw, _ = audioop.ratecv(raw, sample_width, 1, sample_rate, 16000, None)
        duration_ms = int((len(raw) / (16000 * 2)) * 1000)
        return raw, duration_ms

    async def _enqueue_outbound(self, kind: str, payload: Any, priority: int) -> None:
        """Queue outbound message with priority ordering."""
        self._outbound_seq += 1
        await self._outbound_q.put((priority, self._outbound_seq, kind, payload))

    async def _send_event(self, event: Dict[str, Any], priority: int = 20) -> None:
        await self._enqueue_outbound("event", self._envelope_event(event), priority)

    async def _send_audio(self, pcm_bytes: bytes, priority: int = 50) -> None:
        if not pcm_bytes:
            return
        self._audio_out_frame_buffer += pcm_bytes
        while len(self._audio_out_frame_buffer) >= self._PCM_FRAME_BYTES:
            frame = self._audio_out_frame_buffer[: self._PCM_FRAME_BYTES]
            self._audio_out_frame_buffer = self._audio_out_frame_buffer[self._PCM_FRAME_BYTES :]
            await self._enqueue_outbound("audio", frame, priority)

    async def _flush_audio_out_frames(self, priority: int = 50) -> None:
        """Flush remaining outbound audio as one padded 20ms PCM frame."""
        if not self._audio_out_frame_buffer:
            return
        tail = self._audio_out_frame_buffer
        self._audio_out_frame_buffer = b""
        if len(tail) < self._PCM_FRAME_BYTES:
            tail = tail + (b"\x00" * (self._PCM_FRAME_BYTES - len(tail)))
        await self._enqueue_outbound("audio", tail, priority)

    async def _emit_transcript_delta(self, text: str) -> None:
        await self._send_event(
            {
                **ev(
                    "transcript.delta",
                    trackId=self.track_audio_in,
                    text=text,
                )
            },
            priority=30,
        )

    async def _emit_llm_delta(
        self,
        text: str,
        *,
        turn_id: Optional[str] = None,
        utterance_id: Optional[str] = None,
        response_id: Optional[str] = None,
    ) -> None:
        event = {
            **ev(
                "assistant.response.delta",
                trackId=self.track_audio_out,
                text=text,
            )
        }
        if turn_id:
            event["turn_id"] = turn_id
        if utterance_id:
            event["utterance_id"] = utterance_id
        if response_id:
            event["response_id"] = response_id
        await self._send_event(
            event,
            priority=20,
        )

    async def _flush_pending_llm_delta(
        self,
        *,
        turn_id: Optional[str] = None,
        utterance_id: Optional[str] = None,
        response_id: Optional[str] = None,
    ) -> None:
        if not self._pending_llm_delta:
            return
        chunk = self._pending_llm_delta
        self._pending_llm_delta = ""
        self._last_llm_delta_emit_ms = time.monotonic() * 1000.0
        await self._emit_llm_delta(
            chunk,
            turn_id=turn_id,
            utterance_id=utterance_id,
            response_id=response_id,
        )

    async def _outbound_loop(self) -> None:
        """Single sender loop that enforces priority for interrupt events."""
        while True:
            _priority, _seq, kind, payload = await self._outbound_q.get()
            try:
                if kind == "stop":
                    return
                if kind == "audio":
                    if self._drop_outbound_audio:
                        continue
                    await self.transport.send_audio(payload)
                elif kind == "event":
                    await self.transport.send_event(payload)
            except Exception as e:
                logger.error(f"Outbound send error ({kind}): {e}")
            finally:
                self._outbound_q.task_done()

    async def process_audio(self, pcm_bytes: bytes) -> None:
        """
        Process incoming audio chunk.

        This is the main entry point for audio from the user.

        Args:
            pcm_bytes: PCM audio data (16-bit, mono, 16kHz)
        """
        if not self._running:
            return

        try:
            async with self._process_lock:
                if pcm_bytes:
                    self._pre_speech_buffer += pcm_bytes
                    if len(self._pre_speech_buffer) > self._asr_pre_speech_bytes:
                        self._pre_speech_buffer = self._pre_speech_buffer[-self._asr_pre_speech_bytes:]

                # 1. Process through VAD
                vad_result = self.vad_processor.process(pcm_bytes, settings.chunk_size_ms)

                vad_status = "Silence"
                if vad_result:
                    event_type, probability = vad_result
                    vad_status = "Speech" if event_type == "speaking" else "Silence"

                    # Emit VAD event
                    await self.event_bus.publish(event_type, {
                        "trackId": self.track_audio_in,
                        "probability": probability
                    })
                    await self._send_event(
                        ev(
                            "input.speech_started" if event_type == "speaking" else "input.speech_stopped",
                            trackId=self.track_audio_in,
                            probability=probability,
                        ),
                        priority=30,
                    )
                else:
                    # No state change - keep previous status
                    vad_status = self._last_vad_status

                # Update state based on VAD
                if vad_status == "Speech" and self._last_vad_status != "Speech":
                    await self._on_speech_start()

                self._last_vad_status = vad_status

                # 2. Check for barge-in (user speaking while bot speaking)
                # Filter false interruptions by requiring minimum speech duration
                if self._is_bot_speaking and self._barge_in_enabled():
                    if vad_status == "Speech":
                        # User is speaking while bot is speaking
                        self._barge_in_silence_frames = 0  # Reset silence counter

                        if self._barge_in_speech_start_time is None:
                            # Start tracking speech duration
                            self._barge_in_speech_start_time = time.time()
                            self._barge_in_speech_frames = 1
                            logger.debug("Potential barge-in detected, tracking duration...")
                        else:
                            self._barge_in_speech_frames += 1
                            # Check if speech duration exceeds threshold
                            speech_duration_ms = (time.time() - self._barge_in_speech_start_time) * 1000
                            if speech_duration_ms >= self._resolved_barge_in_min_duration_ms():
                                logger.info(f"Barge-in confirmed after {speech_duration_ms:.0f}ms of speech ({self._barge_in_speech_frames} frames)")
                                await self._handle_barge_in()
                    else:
                        # Silence frame during potential barge-in
                        if self._barge_in_speech_start_time is not None:
                            self._barge_in_silence_frames += 1
                            # Allow brief silence gaps (VAD flickering)
                            if self._barge_in_silence_frames > self._barge_in_silence_tolerance_frames():
                                # Too much silence - reset barge-in tracking
                                logger.debug(f"Barge-in cancelled after {self._barge_in_silence_frames} silence frames")
                                self._barge_in_speech_start_time = None
                                self._barge_in_speech_frames = 0
                                self._barge_in_silence_frames = 0
                elif self._is_bot_speaking and not self._barge_in_enabled():
                    self._barge_in_speech_start_time = None
                    self._barge_in_speech_frames = 0
                    self._barge_in_silence_frames = 0

                # 3. Buffer audio for ASR.
                # Gate ASR startup by a short speech-duration threshold to reduce
                # false positives from micro noises, then always close the turn
                # by EOU once ASR has started.
                just_started_asr = False
                if vad_status == "Speech" and not self._asr_capture_active:
                    self._pending_speech_audio += pcm_bytes
                    pending_ms = (len(self._pending_speech_audio) / (settings.sample_rate * 2)) * 1000.0
                    if pending_ms >= self._asr_start_min_speech_ms:
                        await self._start_asr_capture()
                        just_started_asr = True

                if self._asr_capture_active:
                    if not just_started_asr:
                        self._audio_buffer += pcm_bytes
                        if len(self._audio_buffer) > self._max_audio_buffer_bytes:
                            # Keep only the most recent audio to cap memory usage
                            self._audio_buffer = self._audio_buffer[-self._max_audio_buffer_bytes:]
                        await self.asr_service.send_audio(pcm_bytes)

                    # For SiliconFlow ASR, trigger interim transcription periodically
                    # The service handles timing internally via start_interim_transcription()

                # 4. Check for End of Utterance - this triggers LLM response
                if self.eou_detector.process(vad_status, force_eligible=self._asr_capture_active):
                    await self._on_end_of_utterance()
                elif (
                    self._asr_capture_active
                    and self._asr_capture_started_ms > 0.0
                    and (time.monotonic() * 1000.0 - self._asr_capture_started_ms) >= self._ASR_CAPTURE_MAX_MS
                ):
                    logger.warning(
                        f"[EOU] Force finalize after ASR capture timeout: {self._ASR_CAPTURE_MAX_MS}ms"
                    )
                    await self._on_end_of_utterance()
                elif (
                    vad_status == "Silence"
                    and not self.eou_detector.is_speaking
                    and not self._asr_capture_active
                    and self.conversation.state == ConversationState.LISTENING
                ):
                    # Speech was too short to pass ASR gate; reset turn so next
                    # utterance can start cleanly.
                    self._pending_speech_audio = b""
                    self._audio_buffer = b""
                    self._last_sent_transcript = ""
                    await self.conversation.set_state(ConversationState.IDLE)

        except Exception as e:
            logger.error(f"Pipeline audio processing error: {e}", exc_info=True)

    async def process_text(self, text: str) -> None:
        """
        Process text input (chat command).

        Allows direct text input to bypass ASR.

        Args:
            text: User text input
        """
        if not self._running:
            return

        logger.info(f"Processing text input: {text[:50]}...")

        # Cancel any current speaking
        await self._stop_current_speech()

        self._start_turn()
        self._finalize_utterance()

        # Start new turn
        await self.conversation.end_user_turn(text)
        self._current_turn_task = asyncio.create_task(self._handle_turn(text))

    async def interrupt(self) -> None:
        """Interrupt current bot speech (manual interrupt command)."""
        await self._handle_barge_in()

    async def _on_transcript_callback(self, text: str, is_final: bool) -> None:
        """
        Callback for ASR transcription results.

        Streams transcription to client for display.

        Args:
            text: Transcribed text
            is_final: Whether this is the final transcription
        """
        # Avoid sending duplicate transcripts
        if text == self._last_sent_transcript and not is_final:
            return

        now_ms = time.monotonic() * 1000.0
        self._last_sent_transcript = text

        if is_final:
            self._pending_transcript_delta = ""
            self._last_transcript_delta_emit_ms = 0.0
            await self._send_event(
                {
                    **ev(
                        "transcript.final",
                        trackId=self.track_audio_in,
                        text=text,
                    )
                },
                priority=30,
            )
            logger.debug(f"Sent transcript (final): {text[:50]}...")
            return

        self._pending_transcript_delta = text
        should_emit = (
            self._last_transcript_delta_emit_ms <= 0.0
            or now_ms - self._last_transcript_delta_emit_ms >= self._ASR_DELTA_THROTTLE_MS
        )
        if should_emit and self._pending_transcript_delta:
            delta = self._pending_transcript_delta
            self._pending_transcript_delta = ""
            self._last_transcript_delta_emit_ms = now_ms
            await self._emit_transcript_delta(delta)

        if not is_final:
            logger.info(f"[ASR] ASR interim: {text[:100]}")
            logger.debug(f"Sent transcript (interim): {text[:50]}...")

    async def _on_speech_start(self) -> None:
        """Handle user starting to speak."""
        if self.conversation.state in (ConversationState.IDLE, ConversationState.INTERRUPTED):
            self._start_turn()
            self._finalize_utterance()
            await self.conversation.start_user_turn()
            self._audio_buffer = b""
            self._last_sent_transcript = ""
            self.eou_detector.reset()
            self._asr_capture_active = False
            self._asr_capture_started_ms = 0.0
            self._pending_speech_audio = b""

            # Clear ASR buffer. Interim starts only after ASR capture is activated.
            if hasattr(self.asr_service, 'clear_buffer'):
                self.asr_service.clear_buffer()

            logger.debug("User speech started")

    async def _start_asr_capture(self) -> None:
        """Start ASR capture for the current turn after min speech gate passes."""
        if self._asr_capture_active:
            return

        if hasattr(self.asr_service, 'start_interim_transcription'):
            await self.asr_service.start_interim_transcription()

        # Prime ASR with a short pre-speech context window so the utterance
        # start isn't lost while waiting for VAD to transition to Speech.
        pre_roll = self._pre_speech_buffer
        # _pre_speech_buffer already includes current speech frames; avoid
        # duplicating onset audio when we append pending speech below.
        if self._pending_speech_audio and len(pre_roll) > len(self._pending_speech_audio):
            pre_roll = pre_roll[:-len(self._pending_speech_audio)]
        elif self._pending_speech_audio:
            pre_roll = b""
        capture_audio = pre_roll + self._pending_speech_audio
        if capture_audio:
            await self.asr_service.send_audio(capture_audio)
            self._audio_buffer = capture_audio[-self._max_audio_buffer_bytes:]

        self._asr_capture_active = True
        self._asr_capture_started_ms = time.monotonic() * 1000.0
        logger.debug(
            f"ASR capture started after speech gate ({self._asr_start_min_speech_ms}ms), "
            f"capture={len(capture_audio)} bytes"
        )

    async def _on_end_of_utterance(self) -> None:
        """Handle end of user utterance."""
        if self.conversation.state not in (ConversationState.LISTENING, ConversationState.INTERRUPTED):
            # Prevent a stale ASR capture watchdog from repeatedly forcing EOU
            # once the conversation has already moved past user-listening states.
            self._asr_capture_active = False
            self._asr_capture_started_ms = 0.0
            self._pending_speech_audio = b""
            return

        # Add a tiny trailing silence tail to stabilize final-token decoding.
        if self._asr_final_tail_bytes > 0:
            final_tail = b"\x00" * self._asr_final_tail_bytes
            await self.asr_service.send_audio(final_tail)

        # Stop interim transcriptions
        if hasattr(self.asr_service, 'stop_interim_transcription'):
            await self.asr_service.stop_interim_transcription()

        # Get final transcription from ASR service
        user_text = ""

        if hasattr(self.asr_service, 'get_final_transcription'):
            # SiliconFlow ASR - get final transcription
            user_text = await self.asr_service.get_final_transcription()
        elif hasattr(self.asr_service, 'get_and_clear_text'):
            # Buffered ASR - get accumulated text
            user_text = self.asr_service.get_and_clear_text()

        # Skip if no meaningful text
        if not user_text or not user_text.strip():
            logger.debug("[EOU] Detected but no transcription - skipping")
            # Reset for next utterance
            self._audio_buffer = b""
            self._last_sent_transcript = ""
            self._asr_capture_active = False
            self._asr_capture_started_ms = 0.0
            self._pending_speech_audio = b""
            # Return to idle; don't force LISTENING which causes buffering on silence
            await self.conversation.set_state(ConversationState.IDLE)
            return

        logger.info(f"[EOU] Detected - user said: {user_text[:100]}...")
        self._finalize_utterance()

        # For ASR backends that already emitted final via callback,
        # avoid duplicating transcript.final on EOU.
        if user_text != self._last_sent_transcript:
            await self._send_event({
                **ev(
                    "transcript.final",
                    trackId=self.track_audio_in,
                    text=user_text,
                )
            }, priority=25)

        # Clear buffers
        self._audio_buffer = b""
        self._last_sent_transcript = ""
        self._pending_transcript_delta = ""
        self._last_transcript_delta_emit_ms = 0.0
        self._asr_capture_active = False
        self._asr_capture_started_ms = 0.0
        self._pending_speech_audio = b""

        # Process the turn - trigger LLM response
        # Cancel any existing turn to avoid overlapping assistant responses
        await self._stop_current_speech()
        await self.conversation.end_user_turn(user_text)
        self._current_turn_task = asyncio.create_task(self._handle_turn(user_text))

    def _resolved_knowledge_config(self) -> Dict[str, Any]:
        cfg: Dict[str, Any] = {}
        if isinstance(self._runtime_knowledge, dict):
            cfg.update(self._runtime_knowledge)
        kb_id = self._runtime_knowledge_base_id or str(
            cfg.get("kbId") or cfg.get("knowledgeBaseId") or ""
        ).strip()
        if kb_id:
            cfg["kbId"] = kb_id
            cfg.setdefault("enabled", True)
        return cfg

    def _resolved_tool_schemas(self) -> List[Dict[str, Any]]:
        schemas: List[Dict[str, Any]] = []
        seen: set[str] = set()
        for item in self._runtime_tools:
            if isinstance(item, str):
                tool_name = self._normalize_tool_name(item)
                if not tool_name or tool_name in seen:
                    continue
                seen.add(tool_name)
                base = self._DEFAULT_TOOL_SCHEMAS.get(tool_name)
                if base:
                    schemas.append(
                        {
                            "type": "function",
                            "function": {
                                "name": base["name"],
                                "description": base.get("description") or "",
                                "parameters": base.get("parameters") or {"type": "object", "properties": {}},
                            },
                        }
                    )
                else:
                    schemas.append(
                        {
                            "type": "function",
                            "function": {
                                "name": tool_name,
                                "description": f"Execute tool '{tool_name}'",
                                "parameters": {"type": "object", "properties": {}},
                            },
                        }
                    )
                continue

            if not isinstance(item, dict):
                continue

            fn = item.get("function")
            if isinstance(fn, dict) and fn.get("name"):
                fn_name = self._normalize_tool_name(fn.get("name"))
                if not fn_name or fn_name in seen:
                    continue
                seen.add(fn_name)
                schemas.append(
                    {
                        "type": "function",
                        "function": {
                            "name": fn_name,
                            "description": str(fn.get("description") or item.get("description") or ""),
                            "parameters": fn.get("parameters") or {"type": "object", "properties": {}},
                        },
                    }
                )
                continue

            if item.get("name"):
                item_name = self._normalize_tool_name(item.get("name"))
                if not item_name or item_name in seen:
                    continue
                seen.add(item_name)
                schemas.append(
                    {
                        "type": "function",
                        "function": {
                            "name": item_name,
                            "description": str(item.get("description") or ""),
                            "parameters": item.get("parameters") or {"type": "object", "properties": {}},
                        },
                    }
                )
        return schemas

    def _resolved_tool_executor_map(self) -> Dict[str, str]:
        result: Dict[str, str] = {}
        for item in self._runtime_tools:
            if isinstance(item, str):
                name = self._normalize_tool_name(item)
                if name in self._DEFAULT_CLIENT_EXECUTORS:
                    result[name] = "client"
                continue
            if not isinstance(item, dict):
                continue
            fn = item.get("function")
            if isinstance(fn, dict) and fn.get("name"):
                name = self._normalize_tool_name(fn.get("name"))
            else:
                name = self._normalize_tool_name(item.get("name"))
            if not name:
                continue
            executor = str(item.get("executor") or item.get("run_on") or "").strip().lower()
            if executor in {"client", "server"}:
                result[name] = executor
        return result

    def _resolved_tool_default_args_map(self) -> Dict[str, Dict[str, Any]]:
        result: Dict[str, Dict[str, Any]] = {}
        for item in self._runtime_tools:
            if not isinstance(item, dict):
                continue
            fn = item.get("function")
            if isinstance(fn, dict) and fn.get("name"):
                name = self._normalize_tool_name(fn.get("name"))
            else:
                name = self._normalize_tool_name(item.get("name"))
            if not name:
                continue
            raw_defaults = item.get("defaultArgs")
            if raw_defaults is None:
                raw_defaults = item.get("default_args")
            if isinstance(raw_defaults, dict):
                result[name] = dict(raw_defaults)
        return result

    def _resolved_tool_wait_for_response_map(self) -> Dict[str, bool]:
        result: Dict[str, bool] = {}
        for item in self._runtime_tools:
            if not isinstance(item, dict):
                continue
            fn = item.get("function")
            if isinstance(fn, dict) and fn.get("name"):
                name = self._normalize_tool_name(fn.get("name"))
            else:
                name = self._normalize_tool_name(item.get("name"))
            if not name:
                continue
            raw_wait = item.get("waitForResponse")
            if raw_wait is None:
                raw_wait = item.get("wait_for_response")
            if isinstance(raw_wait, bool):
                result[name] = raw_wait
        return result

    def _resolved_tool_id_map(self) -> Dict[str, str]:
        result: Dict[str, str] = {}
        for item in self._runtime_tools:
            if not isinstance(item, dict):
                continue
            fn = item.get("function")
            if isinstance(fn, dict) and fn.get("name"):
                alias = self._normalize_tool_name(fn.get("name"))
            else:
                alias = self._normalize_tool_name(item.get("name"))
            if not alias:
                continue
            tool_id = self._normalize_tool_name(item.get("toolId") or item.get("tool_id") or alias)
            if tool_id:
                result[alias] = tool_id
        return result

    def _resolved_tool_display_name_map(self) -> Dict[str, str]:
        result: Dict[str, str] = {}
        for item in self._runtime_tools:
            if not isinstance(item, dict):
                continue
            fn = item.get("function")
            if isinstance(fn, dict) and fn.get("name"):
                name = self._normalize_tool_name(fn.get("name"))
            else:
                name = self._normalize_tool_name(item.get("name"))
            if not name:
                continue
            display_name = str(
                item.get("displayName")
                or item.get("display_name")
                or name
            ).strip()
            if display_name:
                result[name] = display_name
                tool_id = self._normalize_tool_name(item.get("toolId") or item.get("tool_id") or "")
                if tool_id:
                    result[tool_id] = display_name
        return result

    def _resolved_tool_allowlist(self) -> List[str]:
        names: set[str] = set()
        for item in self._runtime_tools:
            if isinstance(item, str):
                name = self._normalize_tool_name(item)
                if name:
                    names.add(name)
                continue
            if not isinstance(item, dict):
                continue
            fn = item.get("function")
            if isinstance(fn, dict) and fn.get("name"):
                names.add(self._normalize_tool_name(fn.get("name")))
            elif item.get("name"):
                names.add(self._normalize_tool_name(item.get("name")))
        return sorted([name for name in names if name])

    def _resolved_manual_opener_tool_calls(self) -> List[Dict[str, Any]]:
        result: List[Dict[str, Any]] = []
        for item in self._runtime_manual_opener_tool_calls:
            if not isinstance(item, dict):
                continue
            tool_name = self._normalize_tool_name(str(
                item.get("toolName")
                or item.get("tool_name")
                or item.get("name")
                or ""
            ).strip())
            if not tool_name:
                continue
            args_raw = item.get("arguments")
            args: Dict[str, Any] = {}
            if isinstance(args_raw, dict):
                args = dict(args_raw)
            elif isinstance(args_raw, str):
                text_value = args_raw.strip()
                if text_value:
                    try:
                        parsed = json.loads(text_value)
                        if isinstance(parsed, dict):
                            args = parsed
                    except Exception:
                        logger.warning(f"[OpenerTool] ignore invalid JSON args for tool={tool_name}")
            result.append({"toolName": tool_name, "arguments": args})
        return result[:8]

    def _tool_name(self, tool_call: Dict[str, Any]) -> str:
        fn = tool_call.get("function")
        if isinstance(fn, dict):
            return self._normalize_tool_name(fn.get("name"))
        return ""

    def _tool_id_for_name(self, tool_name: str) -> str:
        normalized = self._normalize_tool_name(tool_name)
        return self._normalize_tool_name(self._runtime_tool_id_map.get(normalized) or normalized)

    def _tool_display_name(self, tool_name: str) -> str:
        normalized = self._normalize_tool_name(tool_name)
        return str(self._runtime_tool_display_names.get(normalized) or normalized).strip()

    def _tool_wait_for_response(self, tool_name: str) -> bool:
        normalized = self._normalize_tool_name(tool_name)
        return bool(self._runtime_tool_wait_for_response.get(normalized, False))

    def _tool_executor(self, tool_call: Dict[str, Any]) -> str:
        name = self._tool_name(tool_call)
        if name and name in self._runtime_tool_executor:
            return self._runtime_tool_executor[name]
        # Default to server execution unless explicitly marked as client.
        return "server"

    def _tool_arguments(self, tool_call: Dict[str, Any]) -> Dict[str, Any]:
        fn = tool_call.get("function")
        if not isinstance(fn, dict):
            return {}
        raw = fn.get("arguments")
        if isinstance(raw, dict):
            return raw
        if isinstance(raw, str) and raw.strip():
            try:
                parsed = json.loads(raw)
                return parsed if isinstance(parsed, dict) else {"raw": raw}
            except Exception:
                return {"raw": raw}
        return {}

    def _apply_tool_default_args(self, tool_name: str, args: Dict[str, Any]) -> Dict[str, Any]:
        normalized_tool_name = self._normalize_tool_name(tool_name)
        defaults = self._runtime_tool_default_args.get(normalized_tool_name)
        if not isinstance(defaults, dict) or not defaults:
            return args
        merged = dict(defaults)
        if isinstance(args, dict):
            merged.update(args)
        return merged

    def _build_manual_opener_follow_up_context(self, payload: Dict[str, List[Dict[str, Any]]]) -> str:
        tool_calls = payload.get("toolCalls") if isinstance(payload.get("toolCalls"), list) else []
        tool_results = payload.get("toolResults") if isinstance(payload.get("toolResults"), list) else []
        return (
            "Initial opener tool calls already executed. Continue with a natural assistant follow-up. "
            "If tool results include user selections or values, use them in your response. "
            "Never expose internal tool ids or raw payloads.\n"
            f"opener_tool_calls={json.dumps(tool_calls, ensure_ascii=False)}\n"
            f"opener_tool_results={json.dumps(tool_results, ensure_ascii=False)}"
        )

    async def _execute_manual_opener_tool_calls(self) -> Dict[str, List[Dict[str, Any]]]:
        calls = self._resolved_manual_opener_tool_calls()
        tool_calls_for_context: List[Dict[str, Any]] = []
        tool_results_for_context: List[Dict[str, Any]] = []
        if not calls:
            return {"toolCalls": tool_calls_for_context, "toolResults": tool_results_for_context}

        for call in calls:
            tool_name = str(call.get("toolName") or "").strip()
            if not tool_name:
                continue
            tool_id = self._tool_id_for_name(tool_name)
            tool_display_name = self._tool_display_name(tool_name) or tool_name
            tool_arguments = call.get("arguments") if isinstance(call.get("arguments"), dict) else {}
            merged_tool_arguments = self._apply_tool_default_args(tool_name, tool_arguments)
            call_id = f"call_opener_{uuid.uuid4().hex[:10]}"
            wait_for_response = self._tool_wait_for_response(tool_name)
            tool_call = {
                "id": call_id,
                "type": "function",
                "function": {
                    "name": tool_name,
                    "arguments": json.dumps(merged_tool_arguments, ensure_ascii=False),
                },
            }
            executor = self._tool_executor(tool_call)
            tool_calls_for_context.append(
                {
                    "tool_call_id": call_id,
                    "tool_name": tool_name,
                    "tool_id": tool_id,
                    "tool_display_name": tool_display_name,
                    "arguments": merged_tool_arguments,
                    "wait_for_response": wait_for_response,
                    "executor": executor,
                }
            )

            await self._send_event(
                {
                    **ev(
                        "assistant.tool_call",
                        trackId=self.track_audio_out,
                        tool_call_id=call_id,
                        tool_name=tool_name,
                        tool_id=tool_id,
                        tool_display_name=tool_display_name,
                        wait_for_response=wait_for_response,
                        arguments=merged_tool_arguments,
                        executor=executor,
                        timeout_ms=int(self._TOOL_WAIT_TIMEOUT_SECONDS * 1000),
                        tool_call={**tool_call, "executor": executor, "wait_for_response": wait_for_response},
                    )
                },
                priority=22,
            )
            logger.info(
                f"[OpenerTool] execute name={tool_name} call_id={call_id} executor={executor} "
                f"wait_for_response={wait_for_response}"
            )

            if executor == "client":
                self._pending_client_tool_call_ids.add(call_id)
                if wait_for_response:
                    result = await self._wait_for_single_tool_result(call_id)
                    await self._emit_tool_result(result, source="client")
                    tool_results_for_context.append(result if isinstance(result, dict) else {"tool_call_id": call_id})
                continue

            call_for_executor = dict(tool_call)
            fn_for_executor = (
                dict(call_for_executor.get("function"))
                if isinstance(call_for_executor.get("function"), dict)
                else None
            )
            if isinstance(fn_for_executor, dict):
                fn_for_executor["name"] = tool_id
                call_for_executor["function"] = fn_for_executor
            try:
                result = await asyncio.wait_for(
                    self._server_tool_executor(call_for_executor),
                    timeout=self._SERVER_TOOL_TIMEOUT_SECONDS,
                )
            except asyncio.TimeoutError:
                result = {
                    "tool_call_id": call_id,
                    "name": tool_name,
                    "output": {"message": "server tool timeout"},
                    "status": {"code": 504, "message": "server_tool_timeout"},
                }
            await self._emit_tool_result(result, source="server")
            tool_results_for_context.append(result if isinstance(result, dict) else {"tool_call_id": call_id})

        return {"toolCalls": tool_calls_for_context, "toolResults": tool_results_for_context}

    def _normalize_tool_result(self, result: Dict[str, Any]) -> Dict[str, Any]:
        status = result.get("status") if isinstance(result.get("status"), dict) else {}
        status_code = int(status.get("code") or 0) if status else 0
        status_message = str(status.get("message") or "") if status else ""
        tool_call_id = str(result.get("tool_call_id") or result.get("id") or "")
        tool_name = str(result.get("name") or "unknown_tool")
        tool_display_name = self._tool_display_name(tool_name) or tool_name
        ok = bool(200 <= status_code < 300)
        retryable = status_code >= 500 or status_code in {429, 408}
        error: Optional[Dict[str, Any]] = None
        if not ok:
            error = {
                "code": status_code or 500,
                "message": status_message or "tool_execution_failed",
                "retryable": retryable,
            }
        return {
            "tool_call_id": tool_call_id,
            "tool_name": tool_name,
            "tool_display_name": tool_display_name,
            "ok": ok,
            "error": error,
            "status": {"code": status_code, "message": status_message},
        }

    async def _emit_tool_result(self, result: Dict[str, Any], source: str) -> None:
        tool_name = str(result.get("name") or "unknown_tool")
        tool_display_name = self._tool_display_name(tool_name) or tool_name
        call_id = str(result.get("tool_call_id") or result.get("id") or "")
        status = result.get("status") if isinstance(result.get("status"), dict) else {}
        status_code = int(status.get("code") or 0) if status else 0
        status_message = str(status.get("message") or "") if status else ""
        logger.info(
            f"[Tool] emit result source={source} name={tool_name} call_id={call_id} "
            f"status={status_code} {status_message}".strip()
        )
        normalized = self._normalize_tool_result(result)
        await self._send_event(
            {
                **ev(
                    "assistant.tool_result",
                    trackId=self.track_audio_out,
                    source=source,
                    tool_call_id=normalized["tool_call_id"],
                    tool_name=normalized["tool_name"],
                    tool_display_name=normalized["tool_display_name"],
                    ok=normalized["ok"],
                    error=normalized["error"],
                    result=result,
                )
            },
            priority=22,
        )

    async def handle_tool_call_results(self, results: List[Dict[str, Any]]) -> None:
        """Handle client tool execution results."""
        if not isinstance(results, list):
            return

        for item in results:
            if not isinstance(item, dict):
                continue
            call_id = str(item.get("tool_call_id") or item.get("id") or "").strip()
            if not call_id:
                continue
            if self._pending_client_tool_call_ids and call_id not in self._pending_client_tool_call_ids:
                logger.warning(f"[Tool] ignore unsolicited client result call_id={call_id}")
                continue
            if call_id in self._completed_tool_call_ids:
                logger.debug(f"[Tool] ignore duplicate client result call_id={call_id}")
                continue
            status = item.get("status") if isinstance(item.get("status"), dict) else {}
            status_code = int(status.get("code") or 0) if status else 0
            status_message = str(status.get("message") or "") if status else ""
            tool_name = str(item.get("name") or "unknown_tool")
            logger.info(
                f"[Tool] received client result name={tool_name} call_id={call_id} "
                f"status={status_code} {status_message}".strip()
            )

            waiter = self._pending_tool_waiters.get(call_id)
            if waiter and not waiter.done():
                waiter.set_result(item)
                self._completed_tool_call_ids.add(call_id)
                continue
            self._early_tool_results[call_id] = item
            self._completed_tool_call_ids.add(call_id)

    async def _wait_for_single_tool_result(self, call_id: str) -> Dict[str, Any]:
        if call_id in self._completed_tool_call_ids and call_id not in self._early_tool_results:
            return {
                "tool_call_id": call_id,
                "status": {"code": 208, "message": "tool_call result already handled"},
                "output": "",
            }
        if call_id in self._early_tool_results:
            self._completed_tool_call_ids.add(call_id)
            return self._early_tool_results.pop(call_id)

        loop = asyncio.get_running_loop()
        future = loop.create_future()
        self._pending_tool_waiters[call_id] = future
        try:
            return await asyncio.wait_for(future, timeout=self._TOOL_WAIT_TIMEOUT_SECONDS)
        except asyncio.TimeoutError:
            self._completed_tool_call_ids.add(call_id)
            return {
                "tool_call_id": call_id,
                "status": {"code": 504, "message": "tool_call timeout"},
                "output": "",
            }
        finally:
            self._pending_tool_waiters.pop(call_id, None)
            self._pending_client_tool_call_ids.discard(call_id)

    def _normalize_stream_event(self, item: Any) -> LLMStreamEvent:
        if isinstance(item, LLMStreamEvent):
            return item
        if isinstance(item, str):
            return LLMStreamEvent(type="text_delta", text=item)
        if isinstance(item, dict):
            event_type = str(item.get("type") or "")
            if event_type in {"text_delta", "tool_call", "done"}:
                return LLMStreamEvent(
                    type=event_type,  # type: ignore[arg-type]
                    text=item.get("text"),
                    tool_call=item.get("tool_call"),
                )
        return LLMStreamEvent(type="done")

    async def _handle_turn(self, user_text: str, system_context: Optional[str] = None) -> None:
        """
        Handle a complete conversation turn.

        Uses sentence-by-sentence streaming TTS for lower latency.

        Args:
            user_text: User's transcribed text
        """
        try:
            if not self._current_turn_id:
                self._start_turn()
            if not self._current_utterance_id:
                self._finalize_utterance()
            turn_id = self._current_turn_id
            utterance_id = self._current_utterance_id
            response_id = self._start_response()
            # Start latency tracking
            self._turn_start_time = time.time()
            self._first_audio_sent = False

            full_response = ""
            messages = self.conversation.get_messages()
            if system_context and system_context.strip():
                messages = [*messages, LLMMessage(role="system", content=system_context.strip())]
            max_rounds = 3

            await self.conversation.start_assistant_turn()
            self._is_bot_speaking = True
            self._interrupt_event.clear()
            self._drop_outbound_audio = False

            first_audio_sent = False
            self._pending_llm_delta = ""
            self._last_llm_delta_emit_ms = 0.0
            for _ in range(max_rounds):
                if self._interrupt_event.is_set():
                    break

                sentence_buffer = ""
                pending_punctuation = ""
                round_response = ""
                tool_calls: List[Dict[str, Any]] = []
                allow_text_output = True
                use_engine_sentence_split = self._use_engine_sentence_split_for_tts()

                async for raw_event in self.llm_service.generate_stream(messages):
                    if self._interrupt_event.is_set():
                        break

                    event = self._normalize_stream_event(raw_event)
                    if event.type == "tool_call":
                        await self._flush_pending_llm_delta(
                            turn_id=turn_id,
                            utterance_id=utterance_id,
                            response_id=response_id,
                        )
                        tool_call = event.tool_call if isinstance(event.tool_call, dict) else None
                        if not tool_call:
                            continue
                        allow_text_output = False
                        executor = self._tool_executor(tool_call)
                        enriched_tool_call = dict(tool_call)
                        enriched_tool_call["executor"] = executor
                        tool_name = self._tool_name(enriched_tool_call) or "unknown_tool"
                        tool_id = self._tool_id_for_name(tool_name)
                        tool_display_name = self._tool_display_name(tool_name) or tool_name
                        wait_for_response = self._tool_wait_for_response(tool_name)
                        enriched_tool_call["wait_for_response"] = wait_for_response
                        call_id = str(enriched_tool_call.get("id") or "").strip()
                        fn_payload = (
                            dict(enriched_tool_call.get("function"))
                            if isinstance(enriched_tool_call.get("function"), dict)
                            else None
                        )
                        raw_args = str(fn_payload.get("arguments") or "") if isinstance(fn_payload, dict) else ""
                        tool_arguments = self._tool_arguments(enriched_tool_call)
                        merged_tool_arguments = self._apply_tool_default_args(tool_name, tool_arguments)
                        try:
                            merged_args_text = json.dumps(merged_tool_arguments, ensure_ascii=False)
                        except Exception:
                            merged_args_text = raw_args if raw_args else "{}"
                        if isinstance(fn_payload, dict):
                            fn_payload["arguments"] = merged_args_text
                            enriched_tool_call["function"] = fn_payload
                        args_preview = raw_args if len(raw_args) <= 160 else f"{raw_args[:160]}..."
                        logger.info(
                            f"[Tool] call requested name={tool_name} call_id={call_id} "
                            f"executor={executor} args={args_preview} merged_args={merged_args_text}"
                        )
                        tool_calls.append(enriched_tool_call)
                        if executor == "client" and call_id:
                            self._pending_client_tool_call_ids.add(call_id)
                        await self._send_event(
                            {
                                **ev(
                                    "assistant.tool_call",
                                    trackId=self.track_audio_out,
                                    tool_call_id=call_id,
                                    tool_name=tool_name,
                                    tool_id=tool_id,
                                    tool_display_name=tool_display_name,
                                    wait_for_response=wait_for_response,
                                    arguments=tool_arguments,
                                    executor=executor,
                                    timeout_ms=int(self._TOOL_WAIT_TIMEOUT_SECONDS * 1000),
                                    tool_call=enriched_tool_call,
                                )
                            },
                            priority=22,
                        )
                        continue

                    if event.type != "text_delta":
                        continue

                    text_chunk = event.text or ""
                    if not text_chunk:
                        continue

                    if not allow_text_output:
                        continue

                    full_response += text_chunk
                    round_response += text_chunk
                    sentence_buffer += text_chunk
                    await self.conversation.update_assistant_text(text_chunk)
                    self._pending_llm_delta += text_chunk
                    now_ms = time.monotonic() * 1000.0
                    if (
                        self._last_llm_delta_emit_ms <= 0.0
                        or now_ms - self._last_llm_delta_emit_ms >= self._LLM_DELTA_THROTTLE_MS
                    ):
                        await self._flush_pending_llm_delta(
                            turn_id=turn_id,
                            utterance_id=utterance_id,
                            response_id=response_id,
                        )

                    if use_engine_sentence_split:
                        while True:
                            split_result = extract_tts_sentence(
                                sentence_buffer,
                                end_chars=self._SENTENCE_END_CHARS,
                                trailing_chars=self._SENTENCE_TRAILING_CHARS,
                                closers=self._SENTENCE_CLOSERS,
                                min_split_spoken_chars=self._MIN_SPLIT_SPOKEN_CHARS,
                                hold_trailing_at_buffer_end=True,
                                force=False,
                            )
                            if not split_result:
                                break
                            sentence, sentence_buffer = split_result
                            if not sentence:
                                continue

                            sentence = f"{pending_punctuation}{sentence}".strip()
                            pending_punctuation = ""
                            if not sentence:
                                continue

                            if not has_spoken_content(sentence):
                                pending_punctuation = sentence
                                continue

                            if self._tts_output_enabled() and not self._interrupt_event.is_set():
                                if not first_audio_sent:
                                    tts_id = self._start_tts()
                                    self._mark_client_playback_started(tts_id)
                                    await self._send_event(
                                        {
                                            **ev(
                                                "output.audio.start",
                                                trackId=self.track_audio_out,
                                            ),
                                            "turn_id": turn_id,
                                            "utterance_id": utterance_id,
                                            "response_id": response_id,
                                        },
                                        priority=30,
                                    )
                                    first_audio_sent = True

                                await self._speak_sentence(
                                    sentence,
                                    fade_in_ms=0,
                                    fade_out_ms=8,
                                    turn_id=turn_id,
                                    utterance_id=utterance_id,
                                    response_id=response_id,
                                )

                if use_engine_sentence_split:
                    remaining_text = f"{pending_punctuation}{sentence_buffer}".strip()
                else:
                    remaining_text = sentence_buffer.strip()
                await self._flush_pending_llm_delta(
                    turn_id=turn_id,
                    utterance_id=utterance_id,
                    response_id=response_id,
                )
                if (
                    self._tts_output_enabled()
                    and remaining_text
                    and has_spoken_content(remaining_text)
                    and not self._interrupt_event.is_set()
                ):
                    if not first_audio_sent:
                        tts_id = self._start_tts()
                        self._mark_client_playback_started(tts_id)
                        await self._send_event(
                            {
                                **ev(
                                    "output.audio.start",
                                    trackId=self.track_audio_out,
                                ),
                                "turn_id": turn_id,
                                "utterance_id": utterance_id,
                                "response_id": response_id,
                            },
                            priority=30,
                        )
                        first_audio_sent = True
                    await self._speak_sentence(
                        remaining_text,
                        fade_in_ms=0,
                        fade_out_ms=8,
                        turn_id=turn_id,
                        utterance_id=utterance_id,
                        response_id=response_id,
                    )

                if not tool_calls:
                    break

                tool_results: List[Dict[str, Any]] = []
                for call in tool_calls:
                    call_id = str(call.get("id") or "").strip()
                    if not call_id:
                        continue
                    executor = str(call.get("executor") or "server").strip().lower()
                    tool_name = self._tool_name(call) or "unknown_tool"
                    tool_id = self._tool_id_for_name(tool_name)
                    logger.info(f"[Tool] execute start name={tool_name} call_id={call_id} executor={executor}")
                    if executor == "client":
                        result = await self._wait_for_single_tool_result(call_id)
                        await self._emit_tool_result(result, source="client")
                        tool_results.append(result)
                        continue

                    call_for_executor = dict(call)
                    fn_for_executor = (
                        dict(call_for_executor.get("function"))
                        if isinstance(call_for_executor.get("function"), dict)
                        else None
                    )
                    if isinstance(fn_for_executor, dict):
                        fn_for_executor["name"] = tool_id
                        call_for_executor["function"] = fn_for_executor
                    try:
                        result = await asyncio.wait_for(
                            self._server_tool_executor(call_for_executor),
                            timeout=self._SERVER_TOOL_TIMEOUT_SECONDS,
                        )
                    except asyncio.TimeoutError:
                        result = {
                            "tool_call_id": call_id,
                            "name": self._tool_name(call) or "unknown_tool",
                            "output": {"message": "server tool timeout"},
                            "status": {"code": 504, "message": "server_tool_timeout"},
                        }
                    await self._emit_tool_result(result, source="server")
                    tool_results.append(result)

                messages = [
                    *messages,
                    LLMMessage(
                        role="assistant",
                        content=round_response.strip(),
                    ),
                    LLMMessage(
                        role="system",
                        content=(
                            "Tool execution results are available. "
                            "Continue answering the user naturally using these results. "
                            "Do not request the same tool again in this turn.\n"
                            f"tool_calls={json.dumps(tool_calls, ensure_ascii=False)}\n"
                            f"tool_results={json.dumps(tool_results, ensure_ascii=False)}"
                        ),
                    ),
                ]

            if full_response and not self._interrupt_event.is_set():
                await self._flush_pending_llm_delta(
                    turn_id=turn_id,
                    utterance_id=utterance_id,
                    response_id=response_id,
                )
                await self._send_event(
                    {
                        **ev(
                            "assistant.response.final",
                            trackId=self.track_audio_out,
                            text=full_response,
                        ),
                        "turn_id": turn_id,
                        "utterance_id": utterance_id,
                        "response_id": response_id,
                    },
                    priority=20,
                )

            # Send track end
            if first_audio_sent:
                await self._flush_audio_out_frames(priority=50)
                await self._send_event({
                    **ev(
                        "output.audio.end",
                        trackId=self.track_audio_out,
                    ),
                    "turn_id": turn_id,
                    "utterance_id": utterance_id,
                    "response_id": response_id,
                }, priority=10)

            # End assistant turn
            await self.conversation.end_assistant_turn(
                was_interrupted=self._interrupt_event.is_set()
            )

        except asyncio.CancelledError:
            logger.info("Turn handling cancelled")
            await self.conversation.end_assistant_turn(was_interrupted=True)
        except Exception as e:
            logger.error(f"Turn handling error: {e}", exc_info=True)
            await self.conversation.end_assistant_turn(was_interrupted=True)
        finally:
            self._is_bot_speaking = False
            # Reset barge-in tracking when bot finishes speaking
            self._barge_in_speech_start_time = None
            self._barge_in_speech_frames = 0
            self._barge_in_silence_frames = 0
            self._current_response_id = None
            self._current_tts_id = None

    async def _speak_sentence(
        self,
        text: str,
        fade_in_ms: int = 0,
        fade_out_ms: int = 8,
        turn_id: Optional[str] = None,
        utterance_id: Optional[str] = None,
        response_id: Optional[str] = None,
    ) -> None:
        """
        Synthesize and send a single sentence.

        Args:
            text: Sentence to speak
            fade_in_ms: Fade-in duration for sentence start chunks
            fade_out_ms: Fade-out duration for sentence end chunks
        """
        if not self._tts_output_enabled():
            return

        if not text.strip() or self._interrupt_event.is_set() or not self.tts_service:
            return
            
        logger.info(f"[TTS] split sentence: {text!r}")

        try:
            is_first_chunk = True
            async for chunk in self.tts_service.synthesize_stream(text):
                # Check interrupt at the start of each iteration
                if self._interrupt_event.is_set():
                    logger.debug("TTS sentence interrupted")
                    break

                # Track and log first audio packet latency (TTFB)
                if not self._first_audio_sent and self._turn_start_time:
                    ttfb_ms = (time.time() - self._turn_start_time) * 1000
                    self._first_audio_sent = True
                    logger.info(f"[TTFB] Server first audio packet latency: {ttfb_ms:.0f}ms (session {self.session_id})")

                    # Send TTFB event to client
                    await self._send_event({
                        **ev(
                            "metrics.ttfb",
                            trackId=self.track_audio_out,
                            latencyMs=round(ttfb_ms),
                        ),
                        "turn_id": turn_id,
                        "utterance_id": utterance_id,
                        "response_id": response_id,
                    }, priority=25)

                # Double-check interrupt right before sending audio
                if self._interrupt_event.is_set():
                    break

                smoothed_audio = self._apply_edge_fade(
                    pcm_bytes=chunk.audio,
                    sample_rate=chunk.sample_rate,
                    fade_in=is_first_chunk,
                    fade_out=bool(chunk.is_final),
                    fade_in_ms=fade_in_ms,
                    fade_out_ms=fade_out_ms,
                )
                is_first_chunk = False

                await self._send_audio(smoothed_audio, priority=50)
        except asyncio.CancelledError:
            logger.debug("TTS sentence cancelled")
        except Exception as e:
            logger.error(f"TTS sentence error: {e}")

    def _apply_edge_fade(
        self,
        pcm_bytes: bytes,
        sample_rate: int,
        fade_in: bool = False,
        fade_out: bool = False,
        fade_in_ms: int = 0,
        fade_out_ms: int = 8,
    ) -> bytes:
        """Apply short edge fades to reduce click/pop at sentence boundaries."""
        if not pcm_bytes or (not fade_in and not fade_out):
            return pcm_bytes

        try:
            samples = np.frombuffer(pcm_bytes, dtype="<i2").astype(np.float32)
            if samples.size == 0:
                return pcm_bytes

            if fade_in and fade_in_ms > 0:
                fade_in_samples = int(sample_rate * (fade_in_ms / 1000.0))
                fade_in_samples = max(1, min(fade_in_samples, samples.size))
                samples[:fade_in_samples] *= np.linspace(0.0, 1.0, fade_in_samples, endpoint=True)
            if fade_out:
                fade_out_samples = int(sample_rate * (fade_out_ms / 1000.0))
                fade_out_samples = max(1, min(fade_out_samples, samples.size))
                samples[-fade_out_samples:] *= np.linspace(1.0, 0.0, fade_out_samples, endpoint=True)

            return np.clip(samples, -32768, 32767).astype("<i2").tobytes()
        except Exception:
            # Fallback: never block audio delivery on smoothing failure.
            return pcm_bytes

    async def _speak(self, text: str, audio_event_priority: int = 10) -> None:
        """
        Synthesize and send speech.

        Args:
            text: Text to speak
            audio_event_priority: Priority for output.audio.start/end events
        """
        if not self._tts_output_enabled():
            return

        if not text.strip() or not self.tts_service:
            return

        try:
            self._drop_outbound_audio = False
            # Start latency tracking for greeting
            speak_start_time = time.time()
            first_audio_sent = False

            # Send track start event
            tts_id = self._start_tts()
            self._mark_client_playback_started(tts_id)
            await self._send_event({
                **ev(
                    "output.audio.start",
                    trackId=self.track_audio_out,
                )
            }, priority=audio_event_priority)

            self._is_bot_speaking = True

            # Stream TTS audio
            async for chunk in self.tts_service.synthesize_stream(text):
                if self._interrupt_event.is_set():
                    logger.info("TTS interrupted by barge-in")
                    break

                # Track and log first audio packet latency (TTFB)
                if not first_audio_sent:
                    ttfb_ms = (time.time() - speak_start_time) * 1000
                    first_audio_sent = True
                    logger.info(f"[TTFB] Greeting first audio packet latency: {ttfb_ms:.0f}ms (session {self.session_id})")

                    # Send TTFB event to client
                    await self._send_event({
                        **ev(
                            "metrics.ttfb",
                            trackId=self.track_audio_out,
                            latencyMs=round(ttfb_ms),
                        )
                    }, priority=25)

                # Send audio to client
                await self._send_audio(chunk.audio, priority=50)

                # Small delay to prevent flooding
                await asyncio.sleep(0.01)

            # Send track end event
            await self._flush_audio_out_frames(priority=50)
            await self._send_event({
                **ev(
                    "output.audio.end",
                    trackId=self.track_audio_out,
                )
            }, priority=audio_event_priority)

        except asyncio.CancelledError:
            logger.info("TTS cancelled")
            raise
        except Exception as e:
            logger.error(f"TTS error: {e}")
        finally:
            self._is_bot_speaking = False

    async def _handle_barge_in(self) -> None:
        """Handle user barge-in (interruption)."""
        if not self._is_bot_speaking:
            return

        logger.info("Barge-in detected - interrupting bot speech")

        # Reset barge-in tracking
        self._barge_in_speech_start_time = None
        self._barge_in_speech_frames = 0
        self._barge_in_silence_frames = 0

        # IMPORTANT: Signal interruption FIRST to stop audio sending
        self._interrupt_event.set()
        self._is_bot_speaking = False
        self._drop_outbound_audio = True
        self._audio_out_frame_buffer = b""
        self._clear_client_playback_tracking()
        interrupted_turn_id = self._current_turn_id
        interrupted_utterance_id = self._current_utterance_id
        interrupted_response_id = self._current_response_id

        # Send interrupt event to client IMMEDIATELY
        # This must happen BEFORE canceling services, so client knows to discard in-flight audio
        await self._send_event({
            **ev(
                "response.interrupted",
                trackId=self.track_audio_out,
            ),
            "turn_id": interrupted_turn_id,
            "utterance_id": interrupted_utterance_id,
            "response_id": interrupted_response_id,
        }, priority=0)

        # Cancel TTS
        if self.tts_service:
            await self.tts_service.cancel()

        # Cancel LLM
        if self.llm_service and hasattr(self.llm_service, 'cancel'):
            self.llm_service.cancel()

        # Interrupt conversation only if there is no active turn task.
        # When a turn task exists, it will handle end_assistant_turn() to avoid double callbacks.
        if not (self._current_turn_task and not self._current_turn_task.done()):
            await self.conversation.interrupt()

        # Reset for new user turn
        await self.conversation.start_user_turn()
        self._audio_buffer = b""
        self.eou_detector.reset()
        self._asr_capture_active = False
        self._asr_capture_started_ms = 0.0
        self._pending_speech_audio = b""

    async def _stop_current_speech(self) -> None:
        """Stop any current speech task."""
        self._drop_outbound_audio = True
        self._audio_out_frame_buffer = b""
        self._clear_client_playback_tracking()
        if self._current_turn_task and not self._current_turn_task.done():
            self._interrupt_event.set()
            self._current_turn_task.cancel()
            try:
                await self._current_turn_task
            except asyncio.CancelledError:
                pass

        # Ensure underlying services are cancelled to avoid leaking work/audio
        if self.tts_service:
            await self.tts_service.cancel()
        if self.llm_service and hasattr(self.llm_service, 'cancel'):
            self.llm_service.cancel()

        self._is_bot_speaking = False
        self._interrupt_event.clear()

    async def cleanup(self) -> None:
        """Cleanup pipeline resources."""
        logger.info(f"Cleaning up DuplexPipeline for session {self.session_id}")

        self._running = False
        await self._stop_current_speech()
        if self._outbound_task and not self._outbound_task.done():
            await self._enqueue_outbound("stop", None, priority=-1000)
            await self._outbound_task
            self._outbound_task = None

        # Disconnect services
        if self.llm_service:
            await self.llm_service.disconnect()
        if self.tts_service:
            await self.tts_service.disconnect()
        if self.asr_service:
            await self.asr_service.disconnect()

    def _get_timestamp_ms(self) -> int:
        """Get current timestamp in milliseconds."""
        import time
        return int(time.time() * 1000)

    @property
    def is_speaking(self) -> bool:
        """Check if assistant audio is still active (server send or client playback)."""
        return self._is_bot_speaking or self.is_client_playing_audio

    @property
    def is_client_playing_audio(self) -> bool:
        """Check if client has unacknowledged assistant audio playback."""
        return bool(self._pending_client_playback_tts_ids)

    @property
    def state(self) -> ConversationState:
        """Get current conversation state."""
        return self.conversation.state