diff --git a/src/ai/acp-transport.ts b/src/ai/acp-transport.ts
index aab99f0e3..47bc39da9 100644
--- a/src/ai/acp-transport.ts
+++ b/src/ai/acp-transport.ts
@@ -62,9 +62,19 @@ interface AcpDebugEntry {
   data: unknown
 }
 
+const MAX_LOG_AGE_MS = 5 * 60 * 1000
+
 export const acpDebugLog: AcpDebugEntry[] = []
 
+function pruneOldEntries() {
+  const cutoff = Date.now() - MAX_LOG_AGE_MS
+  while (acpDebugLog.length > 0 && acpDebugLog[0].ts < cutoff) {
+    acpDebugLog.shift()
+  }
+}
+
 export function getAcpDebugText(): string {
+  pruneOldEntries()
   return acpDebugLog.map((e) =>
     `[${new Date(e.ts).toISOString()}] ${e.type}\n${JSON.stringify(e.data, null, 2)}`
   ).join('\n\n---\n\n')
@@ -74,6 +84,22 @@ export function clearAcpDebugLog() {
   acpDebugLog.length = 0
 }
 
+export async function saveAcpDebugLog(): Promise<string | null> {
+  pruneOldEntries()
+  const text = getAcpDebugText()
+  if (!text) return null
+  try {
+    const { writeTextFile } = await import('@tauri-apps/plugin-fs')
+    const { join, desktopDir } = await import('@tauri-apps/api/path')
+    const filename = `acp-debug-${new Date().toISOString().replace(/[:.]/g, '-')}.log`
+    const path = await join(await desktopDir(), filename)
+    await writeTextFile(path, text)
+    return path
+  } catch {
+    return null
+  }
+}
+
 export class ACPChatTransport implements ChatTransport<UIMessage> {
   private session: ACPSession | null = null
   private agentDef: ACPAgentDef
diff --git a/src/components/ChatPanel.vue b/src/components/ChatPanel.vue
index 67eac88f7..98fe45154 100644
--- a/src/components/ChatPanel.vue
+++ b/src/components/ChatPanel.vue
@@ -2,7 +2,7 @@
 import { ScrollAreaRoot, ScrollAreaScrollbar, ScrollAreaThumb, ScrollAreaViewport } from 'reka-ui'
 import { computed, markRaw, nextTick, ref, watch } from 'vue'
 
-import { getAcpDebugText, clearAcpDebugLog } from '@/ai/acp-transport'
+import { getAcpDebugText, clearAcpDebugLog, saveAcpDebugLog } from '@/ai/acp-transport'
 import { copyChatLog } from '@/ai/chat-debug'
 import { clearToolLogEntries, didHitStepLimit } from '@/ai/tools'
 import AcpPermissionDialog from '@/components/chat/AcpPermissionDialog.vue'
@@ -92,6 +92,7 @@ async function handleCopyAcpLog() {
   const text = getAcpDebugText()
   if (!text) return
   await navigator.clipboard.writeText(text)
+  void saveAcpDebugLog()
   acpLogCopied.value = true
   setTimeout(() => { acpLogCopied.value = false }, 1500)
 }