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/distributed/test_mq_connect_ip.py

@@ -0,0 +1,79 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""
+Test that MessageQueue uses the local node's IP for binding,
+not a remote master_addr. This validates the fix for cross-node
+data-parallel where each DP group leader must bind to its own IP.
+
+The bug: multiproc_executor used `parallel_config.master_addr` as
+`connect_ip` for every DP group's MessageQueue. For DP groups whose
+leader is NOT on the master node, binding to master_addr fails with
+"Cannot assign requested address".
+
+The fix: use `get_ip()` (local node IP) instead of `master_addr`.
+"""
+
+import pytest
+import zmq
+
+from vllm.distributed.device_communicators.shm_broadcast import MessageQueue
+from vllm.utils.network_utils import get_ip
+
+
+def test_mq_bind_with_local_ip():
+    """MessageQueue with remote readers should successfully bind
+    when connect_ip is the local node's IP."""
+    # n_reader=2, n_local_reader=1 means 1 remote reader,
+    # which triggers the remote ZMQ socket bind.
+    mq = MessageQueue(
+        n_reader=2,
+        n_local_reader=1,
+        connect_ip=get_ip(),
+    )
+    handle = mq.export_handle()
+    assert handle.remote_subscribe_addr is not None
+    # The bound address should contain our local IP
+    local_ip = get_ip()
+    assert (
+        local_ip in handle.remote_subscribe_addr
+        or f"[{local_ip}]" in handle.remote_subscribe_addr
+    )
+    del mq
+
+
+def test_mq_bind_with_non_local_ip_fails():
+    """MessageQueue should fail to bind when connect_ip is a
+    non-local IP address (simulating the bug where master_addr
+    from a different node was used)."""
+    # Use a non-local IP that we definitely can't bind to.
+    # 198.51.100.1 is from TEST-NET-2 (RFC 5737), never locally assigned.
+    non_local_ip = "198.51.100.1"
+    with pytest.raises(zmq.error.ZMQError, match="Cannot assign requested address"):
+        MessageQueue(
+            n_reader=2,
+            n_local_reader=1,
+            connect_ip=non_local_ip,
+        )
+
+
+def test_mq_bind_defaults_to_local_ip():
+    """When connect_ip is None, MessageQueue should auto-detect
+    the local IP and bind successfully."""
+    mq = MessageQueue(
+        n_reader=2,
+        n_local_reader=1,
+        connect_ip=None,  # should fallback to get_ip()
+    )
+    handle = mq.export_handle()
+    assert handle.remote_subscribe_addr is not None
+    del mq
+
+
+if __name__ == "__main__":
+    test_mq_bind_with_local_ip()
+    print("PASSED: test_mq_bind_with_local_ip")
+    test_mq_bind_with_non_local_ip_fails()
+    print("PASSED: test_mq_bind_with_non_local_ip_fails")
+    test_mq_bind_defaults_to_local_ip()
+    print("PASSED: test_mq_bind_defaults_to_local_ip")
+    print("\nAll tests passed!")