From 3c4c3e0280431e305b25a55f52fbb7a8fab3200b Mon Sep 17 00:00:00 2001
From: Makito <i@maki.to>
Date: Fri, 1 Aug 2025 23:22:43 +0900
Subject: [PATCH] fix(stage-ui): enqueue 2x TTS_FLUSH_INSTRUCTION tokens (#342)

---
 packages/stage-ui/src/stores/chat.ts | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/packages/stage-ui/src/stores/chat.ts b/packages/stage-ui/src/stores/chat.ts
index 22caab36d..c569a9ae0 100644
--- a/packages/stage-ui/src/stores/chat.ts
+++ b/packages/stage-ui/src/stores/chat.ts
@@ -183,10 +183,15 @@ export const useChatStore = defineStore('chat', () => {
         })
         fullText += textPart
       }
-      await parser.end()
 
       // Instruct the TTS pipeline to flush
-      slicesQueue.add({ type: 'text', text: TTS_FLUSH_INSTRUCTION })
+      // 2x TTS_FLUSH_INSTRUCTION tokens are used:
+      // - One should be left in the grapheme cluster reader
+      // - The other should be left in the TTS chunking reader
+      // Because both readers will never be closed in the lifecycle of the app
+      slicesQueue.add({ type: 'text', text: `${TTS_FLUSH_INSTRUCTION}${TTS_FLUSH_INSTRUCTION}` })
+
+      await parser.end()
 
       for (const hook of onStreamEndHooks.value) {
         await hook()