Add vLLM v0.18.1 source tree with KV transfer abort fix

third_party/vllm/ now tracked in git for direct patch management.
Based on vLLM v0.18.1 release with one patch applied:

  vllm/v1/core/sched/scheduler.py:
    Replace fatal assert with graceful skip when KV transfer callback
    arrives for an already-aborted request during PD disaggregated serving.

Future vLLM modifications should be made directly in third_party/vllm/
and committed normally. The patches/ directory is kept as documentation
of what changed from upstream.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

third_party/vllm/tests/models/multimodal/generation/test_keye.py

@@ -0,0 +1,83 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+from dataclasses import asdict
+from typing import NamedTuple
+
+import pytest
+from PIL.Image import Image
+from transformers import AutoProcessor
+
+from vllm import LLM, EngineArgs, SamplingParams
+from vllm.multimodal.utils import encode_image_url
+
+MODEL_NAME = "Kwai-Keye/Keye-VL-8B-Preview"
+
+QUESTION = "What is the content of each image?"
+
+
+class ModelRequestData(NamedTuple):
+    engine_args: EngineArgs
+    prompt: str
+    image_data: list[Image]
+    stop_token_ids: list[int] | None = None
+    chat_template: str | None = None
+    sampling_params: SamplingParams | None = None
+
+
+@pytest.mark.core_model
+@pytest.mark.parametrize("question", [QUESTION])
+def test_keye_vl(
+    image_assets,
+    question: str,
+):
+    images = [asset.pil_image for asset in image_assets]
+    image_urls = [encode_image_url(image) for image in images]
+
+    engine_args = EngineArgs(
+        model=MODEL_NAME,
+        trust_remote_code=True,
+        max_model_len=8192,
+        max_num_seqs=5,
+        limit_mm_per_prompt={"image": len(image_urls)},
+    )
+
+    placeholders = [{"type": "image", "image": url} for url in image_urls]
+    messages = [
+        {
+            "role": "user",
+            "content": [
+                *placeholders,
+                {"type": "text", "text": question},
+            ],
+        },
+    ]
+
+    processor = AutoProcessor.from_pretrained(MODEL_NAME, trust_remote_code=True)
+
+    prompt = processor.apply_chat_template(
+        messages, tokenize=False, add_generation_prompt=True
+    )
+
+    engine_args = asdict(engine_args) | {"seed": 42}
+    llm = LLM(**engine_args)
+
+    sampling_params = SamplingParams(
+        temperature=0.0, max_tokens=256, stop_token_ids=None
+    )
+
+    outputs = llm.generate(
+        {
+            "prompt": prompt,
+            "multi_modal_data": {"image": images},
+        },
+        sampling_params=sampling_params,
+    )
+
+    print("-" * 50)
+    for o in outputs:
+        generated_text = o.outputs[0].text
+        print(generated_text)
+        assert len(generated_text) > 10, (
+            f"Generated text is too short: {generated_text}"
+        )
+        print("-" * 50)