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/examples/pooling/pooling/pooling_online.py

@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""
+Example online usage of Pooling API.
+
+Run `vllm serve <model> --runner pooling`
+to start up the server in vLLM. e.g.
+
+vllm serve internlm/internlm2-1_8b-reward --trust-remote-code
+"""
+
+import argparse
+import pprint
+
+import requests
+
+
+def post_http_request(prompt: dict, api_url: str) -> requests.Response:
+    headers = {"User-Agent": "Test Client"}
+    response = requests.post(api_url, headers=headers, json=prompt)
+    return response
+
+
+def parse_args():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--host", type=str, default="localhost")
+    parser.add_argument("--port", type=int, default=8000)
+
+    return parser.parse_args()
+
+
+def main(args):
+    base_url = f"http://{args.host}:{args.port}"
+    models_url = base_url + "/v1/models"
+    pooing_url = base_url + "/pooling"
+
+    response = requests.get(models_url)
+    model = response.json()["data"][0]["id"]
+
+    # Input like Completions API
+    prompt = {"model": model, "input": "vLLM is great!"}
+    pooling_response = post_http_request(prompt=prompt, api_url=pooing_url)
+    print("-" * 50)
+    print("Pooling Response:")
+    pprint.pprint(pooling_response.json())
+    print("-" * 50)
+
+    # Input like Chat API
+    prompt = {
+        "model": model,
+        "messages": [
+            {
+                "role": "user",
+                "content": [{"type": "text", "text": "vLLM is great!"}],
+            }
+        ],
+    }
+    pooling_response = post_http_request(prompt=prompt, api_url=pooing_url)
+    print("Pooling Response:")
+    pprint.pprint(pooling_response.json())
+    print("-" * 50)
+
+
+if __name__ == "__main__":
+    args = parse_args()
+    main(args)