feat: add optional bot backchannels to prompt pipelines

frontend/src/components/assistant-editor/prompt-editor.tsx

@@ -935,6 +935,7 @@ export function PromptEditor({
                   description="设置实时视频对话时的交互体验"
                 >
                   {form.runtimeMode === "pipeline" ? (
+                    <>
                     <TurnConfigEditor
                       enabled={form.enableInterrupt}
                       config={form.turnConfig}
@@ -945,6 +946,26 @@ export function PromptEditor({
                         updateForm("turnConfig", config)
                       }
                     />
+                    <div className="space-y-2 rounded-xl border border-hairline bg-canvas-soft p-3.5">
+                      <label className="flex items-center justify-between gap-3 text-sm font-medium">
+                        机器人附和
+                        <input type="checkbox" checked={form.turnConfig.botBackchannel?.enabled ?? false}
+                          onChange={event => updateForm("turnConfig", { ...form.turnConfig, botBackchannel: {
+                            enabled: event.target.checked, delaySecs: form.turnConfig.botBackchannel?.delaySecs ?? 4,
+                          } })} />
+                      </label>
+                      <p className="text-xs text-muted-foreground">用户持续讲话时轻声回应“嗯”，每轮最多一次，间隔至少 10 秒。不会触发模型回答，也不会改变用户打断策略。</p>
+                      {form.turnConfig.botBackchannel?.enabled && <label className="flex items-center gap-3 text-xs">
+                        连续讲话等待秒数
+                        <input type="number" min={2} max={15} step={0.5}
+                          className="w-20 rounded-md border border-input bg-background px-2 py-1"
+                          value={form.turnConfig.botBackchannel.delaySecs}
+                          onChange={event => { const value = Number(event.target.value); if (Number.isFinite(value) && value >= 2 && value <= 15) updateForm("turnConfig", {
+                            ...form.turnConfig, botBackchannel: { enabled: true, delaySecs: value },
+                          }); }} />
+                      </label>}
+                    </div>
+                    </>
                   ) : (
                     <p className="text-sm text-muted-foreground">
                       高级抢话与轮次检测当前仅支持 Pipeline 模式。

frontend/src/lib/api.ts

@@ -268,6 +268,7 @@ export type AssistantType =
   | "fastgpt";
 export type RuntimeMode = "pipeline" | "realtime";
 export type TurnConfig = {
+  botBackchannel?: { enabled: boolean; delaySecs: number };
   bargeIn: {
     strategy: "vad" | "transcription";
   };

frontend/src/lib/turn-config.ts

@@ -2,6 +2,7 @@ import type { TurnConfig } from "@/lib/api";
 
 export function defaultTurnConfig(): TurnConfig {
   return {
+    botBackchannel: { enabled: false, delaySecs: 4 },
     bargeIn: { strategy: "vad" },
     vad: {
       confidence: 0.7,
@@ -32,11 +33,13 @@ function numberOr(value: unknown, fallback: number): number {
 export function normalizeTurnConfig(value: unknown): TurnConfig {
   const defaults = defaultTurnConfig();
   const input = record(value);
+  const botBackchannel = record(input.botBackchannel);
   const bargeIn = record(input.bargeIn);
   const vad = record(input.vad);
   const turnDetection = record(input.turnDetection);
 
   return {
+    botBackchannel: { enabled: botBackchannel.enabled === true, delaySecs: numberOr(botBackchannel.delaySecs, 4) },
     bargeIn: {
       strategy:
         bargeIn.strategy === "transcription" ? "transcription" : "vad",