--- baked-ours/v1/attention/backend.py	2026-09-10 19:56:14.000000000 +0200
+++ baked/v1/attention/backend.py	2026-09-11 10:13:47.000000000 +0200
@@ -611,6 +611,26 @@
         self.vllm_config = vllm_config
         self.device = device
         self.kernel_block_size: int | None = None
+        # The DCP geometry this builder's group actually runs at: sharded
+        # groups use the process DCP size; DCP-replicated groups (every rank
+        # holds the full KV) behave as dcp=1 for metadata purposes.
+        from vllm.v1.kv_cache_interface import is_dcp_replicated_spec
+
+        process_dcp_size = vllm_config.parallel_config.decode_context_parallel_size
+        self.dcp_replicated = is_dcp_replicated_spec(kv_cache_spec)
+        if process_dcp_size > 1 and not self.dcp_replicated:
+            from vllm.distributed.parallel_state import get_dcp_group
+
+            try:
+                self.dcp_world_size = get_dcp_group().world_size
+                self.dcp_rank = get_dcp_group().rank_in_group
+            except AssertionError:
+                # DCP group not initialized (unit tests).
+                self.dcp_world_size = process_dcp_size
+                self.dcp_rank = 0
+        else:
+            self.dcp_world_size = 1
+            self.dcp_rank = 0
 
     def set_kernel_block_size(self, kernel_block_size: int) -> None:
         self.kernel_block_size = kernel_block_size
@@ -650,10 +670,7 @@
                     max_num_queries_for_spec,
                 )
 
-        if (
-            self.vllm_config.parallel_config.decode_context_parallel_size > 1
-            and not supports_dcp_with_varlen
-        ):
+        if getattr(self, "dcp_world_size", 1) > 1 and not supports_dcp_with_varlen:
             self.reorder_batch_threshold = 1
 
     @abstractmethod