Fix audio pre-buffer bypass on clients due to network sub-chunking

Raw PCM is split into 32KB sub-chunks for network transmission.
On the client, these sub-chunks arrive nearly simultaneously,
triggering the "second chunk arrived" fast-path which cancelled
the pre-buffer after ~10ms instead of the intended 2000ms.

Now the fast-path only applies on Authority (server) where
chunks represent genuine separate TTS batches. Clients always
wait the full pre-buffer duration via TickComponent timer.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Unreal/PS_AI_Agent/Plugins/PS_AI_ConvAgent/Source/PS_AI_ConvAgent/Private/PS_AI_ConvAgent_ElevenLabsComponent.cpp

@@ -225,6 +225,7 @@ void UPS_AI_ConvAgent_ElevenLabsComponent::StartConversation()
 			APlayerController* PC = GetWorld()->GetFirstPlayerController();
 			bNetIsConversing = true;
 			NetConversatingPlayer = PC;
+			NetConversatingPawn = PC ? PC->GetPawn() : nullptr;
 		}
 		StartConversation_Internal();
 	}
@@ -298,6 +299,7 @@ void UPS_AI_ConvAgent_ElevenLabsComponent::EndConversation()
 		// Reset replicated state so other players can talk to this NPC.
 		bNetIsConversing = false;
 		NetConversatingPlayer = nullptr;
+		NetConversatingPawn = nullptr;
 	}
 	else
 	{
@@ -608,6 +610,7 @@ void UPS_AI_ConvAgent_ElevenLabsComponent::HandleDisconnected(int32 StatusCode,
 	{
 		bNetIsConversing = false;
 		NetConversatingPlayer = nullptr;
+		NetConversatingPawn = nullptr;
 	}
 
 	OnAgentDisconnected.Broadcast(StatusCode, Reason);
@@ -1032,20 +1035,26 @@ void UPS_AI_ConvAgent_ElevenLabsComponent::EnqueueAgentAudio(const TArray<uint8>
 	else if (bPreBuffering)
 	{
 		// Second (or later) audio chunk arrived during pre-buffer period.
-		// We now have both chunks buffered — start playback immediately.
-		bPreBuffering = false;
-		if (bDebug)
+		// On Authority: this means a genuine second TTS chunk arrived from the
+		// WebSocket, so we have enough data buffered — start playback immediately.
+		// On Clients: sub-chunks from network splitting arrive nearly simultaneously,
+		// which would defeat the pre-buffer. Let the timer in TickComponent handle it.
+		if (GetOwnerRole() == ROLE_Authority)
 		{
-			const double NowPb = FPlatformTime::Seconds();
-			const double BufferedMs = (NowPb - PreBufferStartTime) * 1000.0;
-			const double Tpb3 = NowPb - SessionStartTime;
-			UE_LOG(LogPS_AI_ConvAgent_ElevenLabs, Log,
-				TEXT("[T+%.2fs] [Turn %d] Pre-buffer: second chunk arrived (%.0fms buffered). Starting playback."),
-				Tpb3, LastClosedTurnIndex, BufferedMs);
-		}
-		if (AudioPlaybackComponent && !AudioPlaybackComponent->IsPlaying())
-		{
-			AudioPlaybackComponent->Play();
+			bPreBuffering = false;
+			if (bDebug)
+			{
+				const double NowPb = FPlatformTime::Seconds();
+				const double BufferedMs = (NowPb - PreBufferStartTime) * 1000.0;
+				const double Tpb3 = NowPb - SessionStartTime;
+				UE_LOG(LogPS_AI_ConvAgent_ElevenLabs, Log,
+					TEXT("[T+%.2fs] [Turn %d] Pre-buffer: second chunk arrived (%.0fms buffered). Starting playback."),
+					Tpb3, LastClosedTurnIndex, BufferedMs);
+			}
+			if (AudioPlaybackComponent && !AudioPlaybackComponent->IsPlaying())
+			{
+				AudioPlaybackComponent->Play();
+			}
 		}
 		SilentTickCount = 0;
 	}
@@ -1195,6 +1204,7 @@ void UPS_AI_ConvAgent_ElevenLabsComponent::GetLifetimeReplicatedProps(
 	Super::GetLifetimeReplicatedProps(OutLifetimeProps);
 	DOREPLIFETIME(UPS_AI_ConvAgent_ElevenLabsComponent, bNetIsConversing);
 	DOREPLIFETIME(UPS_AI_ConvAgent_ElevenLabsComponent, NetConversatingPlayer);
+	DOREPLIFETIME(UPS_AI_ConvAgent_ElevenLabsComponent, NetConversatingPawn);
 	DOREPLIFETIME(UPS_AI_ConvAgent_ElevenLabsComponent, CurrentEmotion);
 	DOREPLIFETIME(UPS_AI_ConvAgent_ElevenLabsComponent, CurrentEmotionIntensity);
 }
@@ -1210,14 +1220,14 @@ void UPS_AI_ConvAgent_ElevenLabsComponent::OnRep_ConversationState()
 		// on the local pawn, but remote clients never run that code path.
 		if (UPS_AI_ConvAgent_PostureComponent* Posture = Owner->FindComponentByClass<UPS_AI_ConvAgent_PostureComponent>())
 		{
-			if (bNetIsConversing && NetConversatingPlayer)
+			// Use NetConversatingPawn (replicated to ALL clients) instead of
+			// NetConversatingPlayer->GetPawn() — PlayerControllers are only
+			// replicated to their owning client (bOnlyRelevantToOwner=true).
+			if (bNetIsConversing && NetConversatingPawn)
 			{
-				if (APawn* PlayerPawn = NetConversatingPlayer->GetPawn())
-				{
-					Posture->TargetActor = PlayerPawn;
-					Posture->ResetBodyTarget();
-					Posture->bEnableBodyTracking = true;
-				}
+				Posture->TargetActor = NetConversatingPawn;
+				Posture->ResetBodyTarget();
+				Posture->bEnableBodyTracking = true;
 			}
 			else
 			{
@@ -1271,6 +1281,7 @@ void UPS_AI_ConvAgent_ElevenLabsComponent::ServerRequestConversation_Implementat
 
 	bNetIsConversing = true;
 	NetConversatingPlayer = RequestingPlayer;
+	NetConversatingPawn = RequestingPlayer ? RequestingPlayer->GetPawn() : nullptr;
 
 	StartConversation_Internal();
 }
@@ -1289,6 +1300,7 @@ void UPS_AI_ConvAgent_ElevenLabsComponent::ServerReleaseConversation_Implementat
 
 	bNetIsConversing = false;
 	NetConversatingPlayer = nullptr;
+	NetConversatingPawn = nullptr;
 }
 
 void UPS_AI_ConvAgent_ElevenLabsComponent::ServerSendMicAudio_Implementation(

Unreal/PS_AI_Agent/Plugins/PS_AI_ConvAgent/Source/PS_AI_ConvAgent/Public/PS_AI_ConvAgent_ElevenLabsComponent.h

@@ -296,10 +296,15 @@ public:
 	bool bNetIsConversing = false;
 
 	/** The player controller currently in conversation with this NPC (null if free).
-	 *  Replicated so each client knows who is speaking (used for posture target, LOD). */
+	 *  Only valid on server and owning client (PlayerControllers are not replicated to other clients). */
 	UPROPERTY(ReplicatedUsing = OnRep_ConversationState, BlueprintReadOnly, Category = "PS AI ConvAgent|Network")
 	TObjectPtr<APlayerController> NetConversatingPlayer = nullptr;
 
+	/** The pawn of the conversating player. Replicated to ALL clients (unlike PlayerController).
+	 *  Used by remote clients for posture target (head/eye tracking) and LOD distance checks. */
+	UPROPERTY(ReplicatedUsing = OnRep_ConversationState, BlueprintReadOnly, Category = "PS AI ConvAgent|Network")
+	TObjectPtr<APawn> NetConversatingPawn = nullptr;
+
 	// ── Network LOD ──────────────────────────────────────────────────────────
 
 	/** Distance (cm) beyond which remote clients stop receiving agent audio entirely.