diff --git a/web-admin/src/api/aiconfig.ts b/web-admin/src/api/aiconfig.ts
index f724228..94bfd92 100644
--- a/web-admin/src/api/aiconfig.ts
+++ b/web-admin/src/api/aiconfig.ts
@@ -319,6 +319,33 @@ export function normalizeAiText(value?: string): string {
   }
 }
 
+function findOverlapLength(current: string, next: string) {
+  const max = Math.min(current.length, next.length)
+  for (let size = max; size > 0; size -= 1) {
+    if (current.slice(-size) === next.slice(0, size)) return size
+  }
+  return 0
+}
+
+function mergeStreamOutput(current: string, chunk?: string) {
+  const next = normalizeAiText(chunk || '')
+  if (!next) return { output: current, delta: '' }
+  if (!current) return { output: next, delta: next }
+  if (next === current) return { output: current, delta: '' }
+  if (next.length >= 16 && current.endsWith(next)) return { output: current, delta: '' }
+  if (next.startsWith(current)) {
+    return { output: next, delta: next.slice(current.length) }
+  }
+  const currentIndex = next.length > current.length ? next.indexOf(current) : -1
+  if (currentIndex >= 0) {
+    return { output: next, delta: next.slice(currentIndex + current.length) }
+  }
+  const overlap = findOverlapLength(current, next)
+  if (overlap < 8) return { output: current + next, delta: next }
+  const delta = next.slice(overlap)
+  return { output: current + delta, delta }
+}
+
 function extractTextValue(value: any): string {
   if (!value || typeof value !== 'object' || Array.isArray(value)) return ''
   for (const key of ['output', 'answer', 'content', 'text', 'result']) {
@@ -383,7 +410,7 @@ async function fetchSseStream(
       const event = parseSseFrame(frame)
       if (!event) return
       if (event.type === 'delta') {
-        output += normalizeAiText(event.content || '')
+        output = mergeStreamOutput(output, event.content).output
       }
       onEvent(event, output)
       if (event.type === 'error' && finishRecovered(event)) {