perf: guard TTS sentence parsing behind showCallOverlay check (open-webui#22195)

The chatCompletionEventHandler runs getMessageContentParts() and
removeAllDetails() on every streaming token to extract sentences
for real-time TTS dispatch via CustomEvent('chat'). These functions
perform multiple O(n) regex passes over the full accumulated message
content, resulting in O(n^2) total work over a streaming response.

The only consumer of these events is CallOverlay.svelte, which is
only mounted when showCallOverlay is true. Without the overlay open,
the parsing runs but the dispatched events have no listeners.

Wrap all three TTS parsing blocks in an if () guard
so the expensive regex work is skipped entirely for the vast majority
of users who are not using the voice call feature.

Author: Classic298

src/lib/components/chat/Chat.svelte

@@ -1567,27 +1567,29 @@
 						navigator.vibrate(5);
 					}
 
-					// Emit chat event for TTS
-					const messageContentParts = getMessageContentParts(
-						removeAllDetails(message.content),
-						$config?.audio?.tts?.split_on ?? 'punctuation'
-					);
-					messageContentParts.pop();
-
-					// dispatch only last sentence and make sure it hasn't been dispatched before
-					if (
-						messageContentParts.length > 0 &&
-						messageContentParts[messageContentParts.length - 1] !== message.lastSentence
-					) {
-						message.lastSentence = messageContentParts[messageContentParts.length - 1];
-						eventTarget.dispatchEvent(
-							new CustomEvent('chat', {
-								detail: {
-									id: message.id,
-									content: messageContentParts[messageContentParts.length - 1]
-								}
-							})
+					// Emit chat event for TTS (only when call overlay is active)
+					if ($showCallOverlay) {
+						const messageContentParts = getMessageContentParts(
+							removeAllDetails(message.content),
+							$config?.audio?.tts?.split_on ?? 'punctuation'
 						);
+						messageContentParts.pop();
+
+						// dispatch only last sentence and make sure it hasn't been dispatched before
+						if (
+							messageContentParts.length > 0 &&
+							messageContentParts[messageContentParts.length - 1] !== message.lastSentence
+						) {
+							message.lastSentence = messageContentParts[messageContentParts.length - 1];
+							eventTarget.dispatchEvent(
+								new CustomEvent('chat', {
+									detail: {
+										id: message.id,
+										content: messageContentParts[messageContentParts.length - 1]
+									}
+								})
+							);
+						}
 					}
 				}
 			}
@@ -1601,27 +1603,29 @@
 				navigator.vibrate(5);
 			}
 
-			// Emit chat event for TTS
-			const messageContentParts = getMessageContentParts(
-				removeAllDetails(message.content),
-				$config?.audio?.tts?.split_on ?? 'punctuation'
-			);
-			messageContentParts.pop();
-
-			// dispatch only last sentence and make sure it hasn't been dispatched before
-			if (
-				messageContentParts.length > 0 &&
-				messageContentParts[messageContentParts.length - 1] !== message.lastSentence
-			) {
-				message.lastSentence = messageContentParts[messageContentParts.length - 1];
-				eventTarget.dispatchEvent(
-					new CustomEvent('chat', {
-						detail: {
-							id: message.id,
-							content: messageContentParts[messageContentParts.length - 1]
-						}
-					})
+			// Emit chat event for TTS (only when call overlay is active)
+			if ($showCallOverlay) {
+				const messageContentParts = getMessageContentParts(
+					removeAllDetails(message.content),
+					$config?.audio?.tts?.split_on ?? 'punctuation'
 				);
+				messageContentParts.pop();
+
+				// dispatch only last sentence and make sure it hasn't been dispatched before
+				if (
+					messageContentParts.length > 0 &&
+					messageContentParts[messageContentParts.length - 1] !== message.lastSentence
+				) {
+					message.lastSentence = messageContentParts[messageContentParts.length - 1];
+					eventTarget.dispatchEvent(
+						new CustomEvent('chat', {
+							detail: {
+								id: message.id,
+								content: messageContentParts[messageContentParts.length - 1]
+							}
+						})
+						);
+				}
 			}
 		}
 
@@ -1648,18 +1652,20 @@
 				document.getElementById(`speak-button-${message.id}`)?.click();
 			}
 
-			// Emit chat event for TTS
-			let lastMessageContentPart =
-				getMessageContentParts(
-					removeAllDetails(message.content),
-					$config?.audio?.tts?.split_on ?? 'punctuation'
-				)?.at(-1) ?? '';
-			if (lastMessageContentPart) {
-				eventTarget.dispatchEvent(
-					new CustomEvent('chat', {
-						detail: { id: message.id, content: lastMessageContentPart }
-					})
-				);
+			// Emit chat event for TTS (only when call overlay is active)
+			if ($showCallOverlay) {
+				let lastMessageContentPart =
+					getMessageContentParts(
+						removeAllDetails(message.content),
+						$config?.audio?.tts?.split_on ?? 'punctuation'
+					)?.at(-1) ?? '';
+				if (lastMessageContentPart) {
+					eventTarget.dispatchEvent(
+						new CustomEvent('chat', {
+							detail: { id: message.id, content: lastMessageContentPart }
+						})
+					);
+				}
 			}
 			eventTarget.dispatchEvent(
 				new CustomEvent('chat:finish', {