[gRPC] Fix scheduler startup broken by context parallel refactor (#18933)

Co-authored-by: Chang Su <chang.s.su@oracle.com>

python/sglang/srt/grpc/scheduler_launcher.py

@@ -112,8 +112,26 @@ def launch_scheduler_process_only(
                     + (tp_rank % tp_size_per_node) * server_args.gpu_id_step
                 )
 
-                # Calculate MoE expert parallel rank
+                # Calculate parallelism ranks (matching engine.py logic)
-                moe_ep_rank = tp_rank // (server_args.tp_size // server_args.ep_size)
+                attn_dp_size = (
+                    server_args.dp_size if server_args.enable_dp_attention else 1
+                )
+                attn_tp_size = (
+                    server_args.tp_size // attn_dp_size // server_args.attn_cp_size
+                )
+                attn_cp_rank = (tp_rank // attn_tp_size) % server_args.attn_cp_size
+                moe_dp_rank = tp_rank // (
+                    server_args.tp_size // server_args.moe_dp_size
+                )
+                moe_ep_rank = (
+                    tp_rank
+                    % (server_args.tp_size // server_args.moe_dp_size)
+                    // (
+                        server_args.tp_size
+                        // server_args.moe_dp_size
+                        // server_args.ep_size
+                    )
+                )
 
                 # Create scheduler process
                 proc = mp.Process(
@@ -123,6 +141,8 @@ def launch_scheduler_process_only(
                         port_args,
                         gpu_id,
                         tp_rank,
+                        attn_cp_rank,
+                        moe_dp_rank,
                         moe_ep_rank,
                         pp_rank,
                         None,  # dp_rank