fix(zhipu): 修复 send_message_stream yield-in-try-except 及测试死代码;

- 将 send_message_stream 中 yield 移至 try/except 外部，避免
  async generator 意外捕获外部 athrow 抛入的 HTTPStatusError；
- 删除 test_stream_429_retries_and_succeeds 中未生效的首段 mock 代码。

🤖 Generated with [Claude Code](https://github.com/claude), [CodeX](https://openai.com), [Gemini](https://github.com/apps/gemini-code-assist)
Co-Authored-By: Aurelius Huang<threefish.ai@gmail.com>

Author: ThreeFish-AI

src/coding/proxy/vendors/zhipu.py

@@ -115,8 +115,11 @@ async def send_message_stream(
 
         for attempt in range(max_attempts):
             try:
-                async for chunk in super().send_message_stream(request_body, headers):
-                    yield chunk
+                # 429 在 status code 检查阶段即 raise（在任何 chunk 之前），
+                # 因此 __anext__ 安全：要么拿到首个 chunk，要么抛异常。
+                ait = super().send_message_stream(request_body, headers)
+                head = await ait.__anext__()
+            except StopAsyncIteration:
                 return
             except httpx.HTTPStatusError as exc:
                 if exc.response is None or exc.response.status_code != 429:
@@ -136,6 +139,13 @@ async def send_message_stream(
                     delay,
                 )
                 await asyncio.sleep(delay / 1000.0)
+                continue
+
+            # yield 在 try/except 之外，避免捕获外部 athrow 的异常
+            yield head
+            async for chunk in ait:
+                yield chunk
+            return
 
     # ── 延迟计算 ────────────────────────────────────────────
 

tests/test_zhipu.py

@@ -430,39 +430,7 @@ async def mock_post(*args, **kwargs):
 
     @pytest.mark.asyncio
     async def test_stream_429_retries_and_succeeds(self):
-        """流式 429 一次后成功."""
-        vendor = _make_zhipu_vendor()
-        call_count = 0
-
-        async def mock_stream(method, url, **kwargs):
-            nonlocal call_count
-            call_count += 1
-            if call_count == 1:
-                resp = _make_429_response()
-                raise httpx.HTTPStatusError(
-                    "429",
-                    request=resp.request,
-                    response=resp,
-                )
-            # 成功响应
-            resp = httpx.Response(
-                status_code=200,
-                request=httpx.Request("POST", "https://example.com"),
-            )
-            resp._stream = httpx.ByteStream(b'data: {"type":"content_block_start"}\n\n')
-            return resp
-
-        with patch.object(vendor, "_get_client") as mock_client:
-            client = AsyncMock()
-            client.stream = mock_stream
-            mock_client.return_value = client
-
-            # NativeAnthropicVendor.send_message_stream 的 super() 调用
-            # 需要完整的 BaseVendor 流式路径，这里直接验证 retry 逻辑
-            # 通过 mock super().send_message_stream 更简洁
-            pass
-
-        # 使用更直接的方式测试流式重试
+        """流式 429 两次后成功."""
         call_count = 0
 
         async def fake_stream(self, body, headers):