[fix] Fix cuda ipc weight sync after #1271

[erictang000]

Fixes the following error encountered after #1271 when running colocated training w/ cuda ipc weight sync

                                  ^^^^^^^^^^^^^^^^^^^
ray.exceptions.RayTaskError(TypeError): ray::FSDPPolicyWorkerBase.broadcast_to_inference_engines() (pid=238850, ip=10.0.135.49, actor_id=17e6181c4a6c57b58e04aee108000000, repr=<skyrl.backends.skyrl_train.workers.fsdp.fsdp_worker.FSDPPolicyWorkerBase object at 0x7d820dd11df0>)
  File "/home/ray/anaconda3/lib/python3.12/concurrent/futures/_base.py", line 449, in result
    return self.__get_result()
           ^^^^^^^^^^^^^^^^^^^
  File "/home/ray/anaconda3/lib/python3.12/concurrent/futures/_base.py", line 401, in __get_result
    raise self._exception
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/tmp/ray/session_2026-03-06_17-46-17_343270_6070/runtime_resources/working_dir_files/_ray_pkg_3a51306235ee6269/skyrl/backends/skyrl_train/workers/fsdp/fsdp_worker.py", line 256, in broadcast_to_inference_engines
    await self._weight_transfer_sender.send_chunks(
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: CudaIpcWeightTransferSender.send_chunks() got an unexpected keyword argument 'weight_metadata'

---

[gemini-code-assist]

Code Review

This pull request addresses a TypeError that occurs during CUDA IPC weight synchronization by updating the send_chunks method signature in CudaIpcWeightTransferSender. The new signature includes the weight_metadata keyword argument, which aligns it with the base class interface and resolves the error. The method's docstring is also updated to document the new argument.

[devin-ai-integration]

✅ Devin Review: No Issues Found

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