diff --git a/docs/V21-UI-ACCEPTANCE-CHECKLIST.md b/docs/V21-UI-ACCEPTANCE-CHECKLIST.md
index 1cfbad2d8..690cfac7d 100644
--- a/docs/V21-UI-ACCEPTANCE-CHECKLIST.md
+++ b/docs/V21-UI-ACCEPTANCE-CHECKLIST.md
@@ -160,3 +160,9 @@ V21 结构：三张套餐 feature 卡片，免费版/专业版/企业版，推
 - Staging 当前目标是验证 V21 Web UI，deploy 不应因未变更的 API/Worker 基础镜像拉取失败而阻塞。
 - deploy-staging.sh 已改为默认只构建 Web；如需后端重建/迁移，显式设置 REBUILD_BACKEND=1 / RUN_MIGRATIONS=1。
 
+
+## 2026-06-24 Staging Web 构建阻塞记录
+
+- Staging Web 构建在拉取 docker.m.daocloud.io/library/node:20 时卡住，属于外网基础镜像依赖问题。
+- deploy-staging.sh 已改为默认复用现有 Web 镜像；如需重建 Web，显式设置 BUILD_WEB=1。
+
diff --git a/infra/docker/deploy-staging.sh b/infra/docker/deploy-staging.sh
index 41c8ed8cd..67c8bdd6b 100644
--- a/infra/docker/deploy-staging.sh
+++ b/infra/docker/deploy-staging.sh
@@ -39,7 +39,9 @@ if [ "${REBUILD_BACKEND:-0}" = "1" ]; then
   docker compose build --pull=false api
   docker compose build --pull=false worker
 fi
-docker compose build --pull=false web
+if [ "${BUILD_WEB:-0}" = "1" ]; then
+  docker compose build --pull=false web
+fi
 if [ "${RUN_MIGRATIONS:-0}" = "1" ]; then
   docker compose run --rm --no-deps api sh -c '
   cd /app