Add support for Qwen3-seq-cls (#9357)

python/sglang/srt/models/qwen3_classification.py

@@ -42,7 +42,13 @@ class Qwen3ForSequenceClassification(nn.Module):
         # Use normalize=True for qwen3 embedding based on official implementation
         # Reference: https://github.com/QwenLM/Qwen3-Embedding/blob/main/examples/qwen3_embedding_transformers.py#L55
         # Official code: output = F.normalize(output, p=2, dim=1)
-        self.pooler = Pooler(pooling_type=PoolingType.LAST, normalize=True)
+        normalize = True
+
+        # We don't want to normalize the embedding if we have a classification head
+        if config.id2label is not None or config.label2id is not None:
+            normalize = False
+
+        self.pooler = Pooler(pooling_type=PoolingType.LAST, normalize=normalize)
 
         self.eos_token_id = config.eos_token_id