[Feature] Add Qwen3-ForcedAligner support via token classification pooling (#35367)

Signed-off-by: haosdent <haosdent@gmail.com>

tests/models/multimodal/pooling/test_qwen3_asr_forced_aligner.py

@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import numpy as np
+import pytest
+import torch
+
+MODEL = "Qwen/Qwen3-ForcedAligner-0.6B"
+CLASSIFY_NUM = 5000
+TIMESTAMP_TOKEN_ID = 151705
+
+
+def build_prompt(words: list[str]) -> str:
+    body = "<timestamp><timestamp>".join(words) + "<timestamp><timestamp>"
+    return f"<|audio_start|><|audio_pad|><|audio_end|>{body}"
+
+
+@pytest.mark.parametrize("model", [MODEL])
+@pytest.mark.parametrize("dtype", ["bfloat16"])
+@torch.inference_mode()
+def test_qwen3_forced_aligner(
+    vllm_runner,
+    model: str,
+    dtype: str,
+) -> None:
+    words = ["Hello", "world"]
+    prompt = build_prompt(words)
+
+    # 5-second silent audio at 16kHz
+    audio = np.zeros(16000 * 5, dtype=np.float32)
+
+    with vllm_runner(
+        model,
+        runner="pooling",
+        dtype=dtype,
+        enforce_eager=True,
+        max_model_len=512,
+        hf_overrides={
+            "architectures": [
+                "Qwen3ASRForcedAlignerForTokenClassification",
+            ],
+        },
+    ) as vllm_model:
+        outputs = vllm_model.llm.encode(
+            [{"prompt": prompt, "multi_modal_data": {"audio": audio}}],
+            pooling_task="token_classify",
+        )
+
+    # Validate output structure
+    assert len(outputs) == 1
+    logits = outputs[0].outputs.data
+    assert logits.dim() == 2
+    assert logits.shape[1] == CLASSIFY_NUM
+
+    # Validate timestamp extraction
+    token_ids = outputs[0].prompt_token_ids
+    predictions = logits.argmax(dim=-1)
+    ts_indices = [i for i, t in enumerate(token_ids) if t == TIMESTAMP_TOKEN_ID]
+
+    # 2 words x 2 timestamps each (start + end) = 4
+    assert len(ts_indices) == 4
+
+    ts_preds = [predictions[i].item() for i in ts_indices]
+    assert all(p >= 0 for p in ts_preds)
+    # end >= start for each word
+    assert ts_preds[1] >= ts_preds[0]  # Hello
+    assert ts_preds[3] >= ts_preds[2]  # world