Enhance text input processing and LLM interaction in the backend

- Refactor TextInputProcessor to handle immediate and silent text inputs, improving user experience during voice interactions.
- Introduce PassthroughLLMAssistantAggregator to manage LLM responses while preserving context for downstream TTS processing.
- Update event handling for text input and client readiness, ensuring timely updates to the conversation context.
- Modify run_pipeline to integrate new aggregators and streamline message handling, enhancing overall pipeline efficiency.
- Improve message ordering in useVoicePreview to ensure accurate display of chat messages based on timestamps.

backend/services/pipecat/pipeline.py

@@ -13,17 +13,21 @@ from services.pipecat.service_factory import create_services
 from pipecat.audio.vad.silero import SileroVADAnalyzer
 from pipecat.frames.frames import (
     EndFrame,
-    InputTextRawFrame,
     InputTransportMessageFrame,
+    InterruptionFrame,
+    LLMFullResponseEndFrame,
+    LLMFullResponseStartFrame,
     LLMMessagesAppendFrame,
     OutputTransportMessageUrgentFrame,
+    TextFrame,
     TTSSpeakFrame,
 )
 from pipecat.pipeline.pipeline import Pipeline
 from pipecat.pipeline.worker import PipelineParams, PipelineWorker
 from pipecat.processors.aggregators.llm_context import LLMContext
 from pipecat.processors.aggregators.llm_response_universal import (
-    LLMContextAggregatorPair,
+    LLMAssistantAggregator,
+    LLMUserAggregator,
     LLMUserAggregatorParams,
 )
 from pipecat.processors.frame_processor import FrameDirection, FrameProcessor
@@ -57,11 +61,21 @@ def _text_input(message) -> tuple[str, bool] | None:
 
 
 class TextInputProcessor(FrameProcessor):
-    """把 transport 文字消息转换成级联与实时 LLM 都能消费的帧。"""
+    """把 transport 文字消息转换成 LLM 可消费的帧。
+
+    run_immediately(默认/打断):先通过 on_text_input 事件把用户文字交给
+    run_pipeline 登记,再用 broadcast_interruption() 打断当前播报。新的 LLM
+    回复由 assistant aggregator 确认处理完 interruption 后触发。
+    run_immediately=False(RTVI send-text 静默追加):仅把文字写进上下文,
+    不打断、不触发推理。
+    """
 
     def __init__(self):
         super().__init__()
+        # 立即触发的文字(含打断语义)走 on_text_input;静默追加另走一条事件
         self._register_event_handler("on_text_input")
+        self._register_event_handler("on_text_append")
+        self._register_event_handler("on_client_ready")
 
     async def process_frame(self, frame, direction: FrameDirection):
         await super().process_frame(frame, direction)
@@ -70,6 +84,10 @@ class TextInputProcessor(FrameProcessor):
             await self.push_frame(frame, direction)
             return
 
+        if isinstance(frame.message, dict) and frame.message.get("type") == "client-ready":
+            await self._call_event_handler("on_client_ready")
+            return
+
         parsed = _text_input(frame.message)
         if not parsed:
             await self.push_frame(frame, direction)
@@ -77,17 +95,33 @@ class TextInputProcessor(FrameProcessor):
 
         text, run_immediately = parsed
         if run_immediately:
+            # 先登记文字再打断。下一轮 LLM 由 assistant aggregator 在真正处理完
+            # InterruptionFrame 后触发,避免新回复被这次 interruption 一起取消。
+            await self._call_event_handler("on_text_input", text)
             await self.broadcast_interruption()
+        else:
+            await self._call_event_handler("on_text_append", text)
 
-        await self.push_frame(
-            LLMMessagesAppendFrame(
-                messages=[{"role": "user", "content": text}],
-                run_llm=run_immediately,
-            )
-        )
-        if run_immediately:
-            await self.push_frame(InputTextRawFrame(text=text))
-        await self._call_event_handler("on_text_input", text)
+
+class PassthroughLLMAssistantAggregator(LLMAssistantAggregator):
+    """聚合 LLM 回复进上下文,同时继续把回复帧交给下游 TTS。"""
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._register_event_handler("on_interruption_processed")
+
+    async def process_frame(self, frame, direction: FrameDirection):
+        await super().process_frame(frame, direction)
+
+        # LLMAssistantAggregator 默认会消费这些帧。放在 TTS 前用于中断时保存
+        # 已生成前缀时,必须显式透传,否则 TTS 收不到任何 LLM 回复。
+        if isinstance(
+            frame,
+            (LLMFullResponseStartFrame, LLMFullResponseEndFrame, TextFrame),
+        ):
+            await self.push_frame(frame, direction)
+        elif isinstance(frame, InterruptionFrame):
+            await self._call_event_handler("on_interruption_processed")
 
 
 async def run_pipeline(transport, cfg: AssistantConfig) -> None:
@@ -103,9 +137,9 @@ async def run_pipeline(transport, cfg: AssistantConfig) -> None:
     stt, llm, tts = create_services(cfg)
 
     context = LLMContext(messages=[{"role": "system", "content": cfg.prompt}])
-    user_aggregator, assistant_aggregator = LLMContextAggregatorPair(
+    user_aggregator = LLMUserAggregator(
         context,
-        user_params=LLMUserAggregatorParams(
+        params=LLMUserAggregatorParams(
             vad_analyzer=SileroVADAnalyzer(),
             user_turn_strategies=UserTurnStrategies(
                 start=[
@@ -117,6 +151,7 @@ async def run_pipeline(transport, cfg: AssistantConfig) -> None:
             ),
         ),
     )
+    assistant_aggregator = PassthroughLLMAssistantAggregator(context)
     text_input = TextInputProcessor()
 
     pipeline = Pipeline(
@@ -126,9 +161,12 @@ async def run_pipeline(transport, cfg: AssistantConfig) -> None:
             stt,
             user_aggregator,
             llm,
+            # Aggregate the streamed LLM text before TTS. On interruption,
+            # Pipecat commits the generated prefix immediately instead of
+            # waiting for a TTS provider to emit spoken-text/timestamp frames.
+            assistant_aggregator,
             tts,
             transport.output(),
-            assistant_aggregator,
         ]
     )
 
@@ -153,22 +191,58 @@ async def run_pipeline(transport, cfg: AssistantConfig) -> None:
                 )
             )
 
+    greeting_transcript_sent = False
+    pending_text_inputs: list[str] = []
+
+    async def append_user_text_to_context(text: str, *, run_llm: bool) -> None:
+        await worker.queue_frame(
+            LLMMessagesAppendFrame(
+                messages=[{"role": "user", "content": text}],
+                run_llm=run_llm,
+            )
+        )
+
     @user_aggregator.event_handler("on_user_turn_stopped")
     async def on_user_turn_stopped(_aggregator, _strategy, message):
         await queue_transcript("user", message.content, message.timestamp)
 
     @assistant_aggregator.event_handler("on_assistant_turn_stopped")
     async def on_assistant_turn_stopped(_aggregator, message):
+        # 助手半句此刻已写入上下文,上报为 transcript
         await queue_transcript("assistant", message.content, message.timestamp)
 
     @text_input.event_handler("on_text_input")
     async def on_text_input(_processor, text):
+        pending_text_inputs.append(text)
+        # 前端显示不依赖 interruption 后续事件,必须在打断前先排入发送队列。
         await queue_transcript("user", text, time_now_iso8601())
 
+    @assistant_aggregator.event_handler("on_interruption_processed")
+    async def on_interruption_processed(_aggregator):
+        if not pending_text_inputs:
+            return
+        text = pending_text_inputs.pop(0)
+        # assistant aggregator 已处理完 interruption,现在再启动下一轮 LLM。
+        await append_user_text_to_context(text, run_llm=True)
+
+    @text_input.event_handler("on_text_append")
+    async def on_text_append(_processor, text):
+        # 静默追加:写进上下文但不打断、不触发推理;transcript 照常上报
+        await queue_transcript("user", text, time_now_iso8601())
+        await append_user_text_to_context(text, run_llm=False)
+
+    @text_input.event_handler("on_client_ready")
+    async def on_client_ready(_processor):
+        nonlocal greeting_transcript_sent
+        if cfg.greeting and not greeting_transcript_sent:
+            greeting_transcript_sent = True
+            await queue_transcript("assistant", cfg.greeting, time_now_iso8601())
+
     @transport.event_handler("on_client_connected")
     async def on_client_connected(_transport, _client):
         if cfg.greeting:
-            await worker.queue_frame(TTSSpeakFrame(cfg.greeting))
+            context.add_message({"role": "assistant", "content": cfg.greeting})
+            await worker.queue_frame(TTSSpeakFrame(cfg.greeting, append_to_context=False))
 
     @transport.event_handler("on_client_disconnected")
     async def on_client_disconnected(_transport, _client):

frontend/src/hooks/use-voice-preview.ts

@@ -54,6 +54,11 @@ function errorMessage(error: unknown, fallback: string): string {
   return fallback;
 }
 
+function messageOrder(message: ChatMessage): number {
+  const timestamp = Date.parse(message.timestamp);
+  return Number.isNaN(timestamp) ? Number.MAX_SAFE_INTEGER : timestamp;
+}
+
 function microphoneErrorMessage(error: unknown): string {
   if (error instanceof DOMException) {
     if (error.name === "NotAllowedError") {
@@ -137,6 +142,7 @@ export function useVoicePreview(assistantId: string | null) {
     const channel = dataChannelRef.current;
     dataChannelRef.current = null;
     if (channel) {
+      channel.onopen = null;
       channel.onmessage = null;
       channel.close();
     }
@@ -290,6 +296,9 @@ export function useVoicePreview(assistantId: string | null) {
       // 由浏览器侧主动创建,后端 SmallWebRTCConnection 的 on("datachannel") 会接住。
       const channel = pc.createDataChannel("chat");
       dataChannelRef.current = channel;
+      channel.onopen = () => {
+        channel.send(JSON.stringify({ type: "client-ready" }));
+      };
       channel.onmessage = (event) => {
         try {
           const msg = JSON.parse(event.data);
@@ -309,7 +318,14 @@ export function useVoicePreview(assistantId: string | null) {
                   ? msg.timestamp
                   : new Date().toISOString(),
             };
-            setMessages((prev) => [...prev, next]);
+            setMessages((prev) =>
+              [...prev, next].sort(
+                (a, b) =>
+                  messageOrder(a) - messageOrder(b) ||
+                  Number(a.id.replace("msg-", "")) -
+                    Number(b.id.replace("msg-", "")),
+              ),
+            );
           }
         } catch {
           /* 非 JSON / 未知消息,忽略 */