diff --git a/backend/routers/config.py b/backend/routers/config.py
index 515e3e5..5abc917 100644
--- a/backend/routers/config.py
+++ b/backend/routers/config.py
@@ -300,8 +300,14 @@ def _ensure_upload_keys(config: dict) -> bool:
 
 
 def _migrate_old_themes(config: dict) -> bool:
-    """将旧式目录皮肤迁移为 ZIP 存入 data/skins/，返回是否有变更"""
-    changed = False
+    """将旧式目录皮肤迁移为 ZIP 存入 data/skins/，返回是否有变更。
+
+    仅在首次执行（用旧配置升级时）生效，之后写入标记跳过：否则每次 load_config()
+    都会重新执行——一旦某个皮肤被删除，只要对应证书的 theme 仍引用它、且旧版
+    themes 目录还在，就会被立刻重新生成，导致皮肤包无法真正删除。
+    """
+    if config.get("_legacy_themes_migrated"):
+        return False
     themes_dir = AUTOMATION_DIR / "themes"
     for app_id, app in config.get("apps", {}).items():
         upload_key = app.get("upload_key", "")
@@ -336,8 +342,8 @@ def _migrate_old_themes(config: dict) -> bool:
                 app["skins"] = skins
             if theme != skin_name:
                 cert["theme"] = skin_name
-            changed = True
-    return changed
+    config["_legacy_themes_migrated"] = True
+    return True
 
 
 def load_config() -> dict:
diff --git a/backend/routers/tasks.py b/backend/routers/tasks.py
index b0a94f9..2982b6f 100644
--- a/backend/routers/tasks.py
+++ b/backend/routers/tasks.py
@@ -3,6 +3,7 @@ import os
 import json
 import shutil
 import tempfile
+import time
 import uuid
 from datetime import datetime
 from typing import List
@@ -18,6 +19,10 @@ from ..deps import get_current_user
 
 router = APIRouter(prefix="/api/tasks", tags=["tasks"], dependencies=[Depends(get_current_user)])
 
+# 同一用户对同一任务连击下载按钮时，短时间内只记一次操作日志，避免刷屏
+_DOWNLOAD_LOG_DEBOUNCE_SECONDS = 5
+_recent_download_logs: dict[str, float] = {}
+
 
 @router.post("", response_model=TaskResponse)
 async def create_task(task: TaskCreate, request: Request, user: dict = Depends(get_current_user), db: Session = Depends(get_db)):
@@ -276,11 +281,22 @@ async def get_download_link(task_id: str, request: Request, user: dict = Depends
         )
     except (json.JSONDecodeError, DistributionError) as exc:
         raise HTTPException(status_code=502, detail=f"生成下载链接失败：{exc}") from exc
-    from ..services.audit_log import record_operation
-    record_operation(db, user, "ipa_download_requested", request=request, task=task,
-                     resource_type="ipa", resource_name=task.oss_url,
-                     detail={"controlled": True})
-    db.commit()
+
+    debounce_key = f"{user.get('username')}:{task_id}"
+    now = time.monotonic()
+    last = _recent_download_logs.get(debounce_key)
+    if last is None or now - last > _DOWNLOAD_LOG_DEBOUNCE_SECONDS:
+        if len(_recent_download_logs) > 500:
+            cutoff = now - _DOWNLOAD_LOG_DEBOUNCE_SECONDS
+            for key, ts in list(_recent_download_logs.items()):
+                if ts < cutoff:
+                    del _recent_download_logs[key]
+        _recent_download_logs[debounce_key] = now
+        from ..services.audit_log import record_operation
+        record_operation(db, user, "ipa_download_requested", request=request, task=task,
+                         resource_type="ipa", resource_name=task.oss_url,
+                         detail={"controlled": True})
+        db.commit()
     return {"url": download_url, "expires_in": DOWNLOAD_URL_EXPIRE_SECONDS}
 
 
diff --git a/frontend/src/views/HistoryView.vue b/frontend/src/views/HistoryView.vue
index 95ab8a0..26806d9 100644
--- a/frontend/src/views/HistoryView.vue
+++ b/frontend/src/views/HistoryView.vue
@@ -56,7 +56,7 @@
                 <img v-if="task.build_type === 'Ad_Hoc' && task.qr_code_path"
                      :src="task.qr_code_path" alt="QR" class="qr-thumb"
                      @click="showQrPreview(task)">
-                <button v-if="task.build_type === 'App_Store'" class="download-link" @click="downloadIpa(task.id)">下载 IPA</button>
+                <button v-if="task.build_type === 'App_Store'" class="download-link" :disabled="!!downloadingIds[task.id]" @click="downloadIpa(task.id)">{{ downloadingIds[task.id] ? '下载中...' : '下载 IPA' }}</button>
               </template>
               <span v-else class="text-muted">-</span>
             </td>
@@ -159,7 +159,7 @@
 </template>
 
 <script setup>
-import { ref, computed, onMounted, nextTick, onUnmounted, inject } from 'vue'
+import { ref, reactive, computed, onMounted, nextTick, onUnmounted, inject } from 'vue'
 
 const getToken = inject('getToken', () => '')
 const isAdmin = inject('isAdmin', ref(false))
@@ -182,6 +182,7 @@ const logContainer = ref(null)
 const showVerboseLogs = ref(false)
 const qrPreview = ref(null)
 const showSuperseded = ref(false)
+const downloadingIds = reactive({})
 let logWs = null
 
 const getAppVersion = (task) => {
@@ -313,6 +314,8 @@ const downloadDsym = (taskId) => {
 }
 
 const downloadIpa = async (taskId) => {
+  if (downloadingIds[taskId]) return
+  downloadingIds[taskId] = true
   try {
     const res = await authFetch(`/api/tasks/${taskId}/download-link`)
     if (!res.ok) throw new Error()
@@ -320,6 +323,8 @@ const downloadIpa = async (taskId) => {
     window.open(url, '_blank')
   } catch {
     alert('下载失败，请稍后重试')
+  } finally {
+    delete downloadingIds[taskId]
   }
 }
 
@@ -524,6 +529,8 @@ const errorCategoryLabel = (cat) => {
 .btn-close-log:hover { border-color: #1890ff; color: #1890ff; }
 .download-link { color: #1890ff; text-decoration: none; font-size: 13px; border: none; background: none; cursor: pointer; padding: 0; }
 .download-link:hover { text-decoration: underline; }
+.download-link:disabled { color: #999; cursor: default; }
+.download-link:disabled:hover { text-decoration: none; }
 .text-muted { color: #999; font-size: 13px; }
 .qr-thumb { width: 40px; height: 40px; cursor: pointer; border-radius: 4px; border: 1px solid #e8e8e8; }
 .qr-thumb:hover { border-color: #1890ff; }