diff --git a/frontend/src/App.vue b/frontend/src/App.vue
index 8ed5c79..0b3119a 100644
--- a/frontend/src/App.vue
+++ b/frontend/src/App.vue
@@ -1049,20 +1049,21 @@ async function sendAiChat() {
       // Parse location hint from AI response
       const firstNewline = fullText.indexOf('\n')
       const hint = firstNewline > -1 ? fullText.substring(0, firstNewline).trim().toUpperCase() : ''
-      const editContent = firstNewline > -1 ? fullText.substring(firstNewline + 1) : fullText
+      const knownHints = ['APPEND', 'PREPEND', 'CURSOR', 'INSERT', 'REPLACE']
+      const isHint = knownHints.includes(hint)
+      const editContent = isHint ? fullText.substring(firstNewline + 1) : fullText
 
-      if (hint === 'APPEND') {
-        content.value = content.value.trimEnd() + '\n\n' + editContent
+      if (hint === 'REPLACE') {
+        content.value = editContent
       } else if (hint === 'PREPEND') {
         content.value = editContent + '\n\n' + content.value
-      } else if (hint === 'CURSOR' || hint === 'INSERT') {
-        // Insert at cursor position
+      } else if (hint === 'APPEND') {
+        content.value = content.value.trimEnd() + '\n\n' + editContent
+      } else {
+        // Default: insert at cursor position
         const ta = editor.value
         const pos = ta ? ta.selectionStart : content.value.length
-        content.value = content.value.substring(0, pos) + editContent + content.value.substring(pos)
-      } else {
-        // REPLACE or unknown — replace entire document
-        content.value = hint === 'REPLACE' ? editContent : fullText
+        content.value = content.value.substring(0, pos) + '\n' + (isHint ? editContent : fullText) + content.value.substring(pos)
       }
       isDirty.value = true
       aiChatResponse.value = 'Document updated.'