Define state summary proto

proto/beacon/p2p/v1/types.proto

@@ -73,3 +73,16 @@ message HistoricalBatch {
   repeated bytes block_roots = 1 [(gogoproto.moretags) = "ssz-size:\"block_roots.size\""];
   repeated bytes state_roots = 2 [(gogoproto.moretags) = "ssz-size:\"state_roots.size\""];
 }
+
+// The state summary object is defined for summarizing a state
+// of a given slot. The summary facilitates regeneration of a
+// specific state to allow easy playback using pre-saved state
+// and blocks.
+message StateSummary {
+  // The slot of the state.
+  uint64 slot = 1;
+  // The block root of the state.
+  bytes root = 2;
+  // The block root at epoch boundary of the state.
+  bytes boundary_root = 3;
+}