[Feature] Support loading weights from ckpt engine worker (#11755)

Signed-off-by: Yang Kaiyong <yangkaiyong.yky@antgroup.com>
Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Signed-off-by: Xuchun Shang <xuchun.shang@gmail.com>
Co-authored-by: Yang Kaiyong <yangkaiyong.yky@antgroup.com>
Co-authored-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Co-authored-by: Xuchun Shang <xuchun.shang@gmail.com>
Co-authored-by: Shangming Cai <csmthu@gmail.com>

python/sglang/srt/managers/io_struct.py

@@ -1080,6 +1080,24 @@ class InitWeightsSendGroupForRemoteInstanceReqInput(BaseReq):
     backend: str = "nccl"
 
 
+# Now UpdateWeightsFromIPCReqInput and UpdateWeightsFromIPCReqOutput
+# are only used by Checkpoint Engine (https://github.com/MoonshotAI/checkpoint-engine)
+@dataclass
+class UpdateWeightsFromIPCReqInput(BaseReq):
+    # ZMQ socket paths for each device UUID
+    zmq_handles: Dict[str, str]
+    # Whether to flush cache after weight update
+    flush_cache: bool = True
+    # Optional: Update weight version along with weights
+    weight_version: Optional[str] = None
+
+
+@dataclass
+class UpdateWeightsFromIPCReqOutput(BaseReq):
+    success: bool
+    message: str
+
+
 @dataclass
 class InitWeightsSendGroupForRemoteInstanceReqOutput(BaseReq):
     success: bool