[Bugfix][Frontend] Preserve caller parameters in offline pooling (#58842)

Signed-off-by: 子华 <huaxi.shx@alibaba-inc.com>
Co-authored-by: Codex <noreply@openai.com>

vllm/entrypoints/pooling/base/io_processor.py

@@ -207,7 +207,10 @@ class PoolingIOProcessor:
         else:
             pooling_params = ctx.pooling_params
 
-        params_seq = self._params_to_seq(pooling_params, num_requests)
+        # Clone to avoid modifying the caller's pooling parameters.
+        params_seq = [
+            param.clone() for param in self._params_to_seq(pooling_params, num_requests)
+        ]
 
         for param in params_seq:
             if param.task is None:

vllm/entrypoints/pooling/pooling/io_processor.py

@@ -168,7 +168,7 @@ class PluginWithIOProcessorPlugins(PoolingIOProcessor):
             pooling_params = ctx.pooling_params
 
         params_seq: list[PoolingParams] = [
-            self.io_processor.merge_pooling_params(param)
+            self.io_processor.merge_pooling_params(param.clone())
             for param in self._params_to_seq(
                 pooling_params,
                 num_requests,