Add complementary info in the replay buffer

- Added complementary info in the add method
- Added complementary info in the sample method

lerobot/scripts/server/buffer.py

@@ -244,6 +244,11 @@ class ReplayBuffer:
 
         self.dones = torch.empty((self.capacity,), dtype=torch.bool, device=self.storage_device)
         self.truncateds = torch.empty((self.capacity,), dtype=torch.bool, device=self.storage_device)
+
+        # Initialize complementary_info storage
+        self.complementary_info_keys = []
+        self.complementary_info_storage = {}
+        
         self.initialized = True
 
     def __len__(self):
@@ -277,6 +282,30 @@ class ReplayBuffer:
         self.dones[self.position] = done
         self.truncateds[self.position] = truncated
 
+        # Store complementary info if provided
+        if complementary_info is not None:
+            # Initialize storage for new keys on first encounter
+            for key, value in complementary_info.items():
+                if key not in self.complementary_info_keys:
+                    self.complementary_info_keys.append(key)
+                    if isinstance(value, torch.Tensor):
+                        shape = value.shape if value.ndim > 0 else (1,)
+                        self.complementary_info_storage[key] = torch.zeros(
+                            (self.capacity, *shape), 
+                            dtype=value.dtype, 
+                            device=self.storage_device
+                        )
+                        
+                # Store the value
+                if key in self.complementary_info_storage:
+                    if isinstance(value, torch.Tensor):
+                        self.complementary_info_storage[key][self.position] = value
+                    else:
+                        # For non-tensor values (like grasp_penalty)
+                        self.complementary_info_storage[key][self.position] = torch.tensor(
+                            value, device=self.storage_device
+                    )
+
         self.position = (self.position + 1) % self.capacity
         self.size = min(self.size + 1, self.capacity)
 
@@ -335,6 +364,13 @@ class ReplayBuffer:
         batch_dones = self.dones[idx].to(self.device).float()
         batch_truncateds = self.truncateds[idx].to(self.device).float()
 
+        # Add complementary_info to batch if it exists
+        batch_complementary_info = {}
+        if hasattr(self, 'complementary_info_keys') and self.complementary_info_keys:
+            for key in self.complementary_info_keys:
+                if key in self.complementary_info_storage:
+                    batch_complementary_info[key] = self.complementary_info_storage[key][idx].to(self.device)
+
         return BatchTransition(
             state=batch_state,
             action=batch_actions,
@@ -342,6 +378,7 @@ class ReplayBuffer:
             next_state=batch_next_state,
             done=batch_dones,
             truncated=batch_truncateds,
+            complementary_info=batch_complementary_info if batch_complementary_info else None,
         )
 
     @classmethod