fix(cli): insert voice transcription at cursor position instead of ap… (#26287)

Co-authored-by: Zheyuan <zlin252@emory.edu>

packages/cli/src/ui/hooks/useVoiceMode.ts

@@ -51,6 +51,7 @@ export function useVoiceMode({
   const recorderRef = useRef<AudioRecorder | null>(null);
   const transcriptionServiceRef = useRef<TranscriptionProvider | null>(null);
   const turnBaselineRef = useRef<string | null>(null);
+  const turnBaselineCursorOffsetRef = useRef<number>(0);
 
   const pttStateRef = useRef<'idle' | 'possible-hold' | 'recording'>('idle');
   const pttTimerRef = useRef<NodeJS.Timeout | null>(null);
@@ -112,6 +113,7 @@ export function useVoiceMode({
 
     recordingInProgressRef.current = true;
     turnBaselineRef.current = bufferRef.current.text;
+    turnBaselineCursorOffsetRef.current = bufferRef.current.getOffset();
 
     setIsConnecting(true);
     setIsRecording(true);
@@ -193,29 +195,23 @@ export function useVoiceMode({
         }
 
         if (text) {
-          const currentBufferText = bufferRef.current.text;
-          const previousTranscription = liveTranscriptionRef.current;
+          const baseline = turnBaselineRef.current ?? '';
+          const insertOffset = turnBaselineCursorOffsetRef.current;
+          const textBefore = baseline.slice(0, insertOffset);
+          const textAfter = baseline.slice(insertOffset);
 
-          let newTotalText = currentBufferText;
+          const prefix =
+            textBefore.length > 0 && !/\s$/.test(textBefore)
+              ? textBefore + ' '
+              : textBefore;
 
-          if (
-            previousTranscription &&
-            currentBufferText.endsWith(previousTranscription)
-          ) {
-            newTotalText = currentBufferText.slice(
-              0,
-              -previousTranscription.length,
-            );
-          } else if (
-            currentBufferText &&
-            !currentBufferText.endsWith(' ') &&
-            !currentBufferText.endsWith('\n')
-          ) {
-            newTotalText += ' ';
-          }
+          const suffix =
+            text.length > 0 && textAfter.length > 0 && !/^\s/.test(textAfter)
+              ? ' '
+              : '';
 
-          newTotalText += text;
-          bufferRef.current.setText(newTotalText, 'end');
+          const newTotalText = prefix + text + suffix + textAfter;
+          bufferRef.current.setText(newTotalText, prefix.length + text.length);
         }
         liveTranscriptionRef.current = text;
       });
@@ -226,6 +222,9 @@ export function useVoiceMode({
           stopRequestedRef.current
         )
           return;
+        // Advance the baseline so subsequent turns append after this turn's text
+        turnBaselineRef.current = bufferRef.current.text;
+        turnBaselineCursorOffsetRef.current = bufferRef.current.getOffset();
         liveTranscriptionRef.current = '';
       });