align vercel stream finalization with go

docs/DEPLOY.en.md

@@ -301,6 +301,7 @@ Vercel Go Runtime applies platform-level response buffering, so this project use
 
 - `api/chat-stream.js` falls back to Go entry (`?__go=1`) for non-stream requests only
 - Streaming requests (including requests with `tools`) stay on the Node path and use Go-aligned tool-call anti-leak handling
+- The Node stream path also mirrors Go finalization semantics: empty visible output returns the same shaped error SSE, and empty `content_filter` returns a `content_filter` error
 - WebUI non-stream test calls `?__go=1` directly to avoid Node hop timeout on long requests
 
 #### Function Duration

docs/DEPLOY.md

@@ -311,6 +311,7 @@ api/index.go  api/chat-stream.js
 
 - `api/chat-stream.js` 仅对非流式请求回退到 Go 入口（`?__go=1`）
 - 流式请求（包括带 `tools`）走 Node 路径，并执行与 Go 对齐的 tool-call 防泄漏处理
+- Node 流式路径同时对齐 Go 的终结态语义：空可见输出会返回同形状错误 SSE，空 `content_filter` 会返回 `content_filter` 错误
 - WebUI 的"非流式测试"直接请求 `?__go=1`，避免 Node 中转造成长请求超时
 
 #### 函数时长