fix(langgraph): preserve state history coverage semantics

src/cleveragents/langgraph/nodes.py

@@ -223,8 +223,11 @@ class Node:  # pylint: disable=too-many-instance-attributes
         full_history_enabled = self.config.metadata.get("full_history", False)
         if full_history_enabled:
             trimmed_history = list(state.messages)
+            history_truncated = False
         else:
-            trimmed_history, _ = self._prepare_conversation_history(state.messages)
+            trimmed_history, history_truncated = self._prepare_conversation_history(
+                state.messages
+            )
 
         # Build a node config that explicitly contains conversation history
         # so the executor layer can pass it to the agent process_message call.
@@ -255,6 +258,9 @@ class Node:  # pylint: disable=too-many-instance-attributes
             "full_context": True,
             "node_config": config_with_history.model_dump(),
         }
+        if history_truncated:
+            context["_history_truncated"] = True
+            context["_history_original_length"] = len(state.messages)
         if state.metadata:
             context.update(state.metadata)
         nested_context = context.get("context")

src/cleveragents/langgraph/state.py

@@ -245,6 +245,16 @@ class ConversationStateManager:  # pylint: disable=too-many-instance-attributes
             if self.is_closed:
                 raise RuntimeError("StateManager is closed")
 
+            if self.enable_time_travel:
+                snapshot = StateSnapshot(
+                    state=self._full_state().to_dict(),
+                    timestamp=datetime.now(),
+                    node_id=node_id,
+                )
+                self._snapshots.append(snapshot)
+                if len(self._snapshots) > self.max_history_size:
+                    self._snapshots = self._snapshots[-self.max_history_size :]
+
             self._execution_state.execution_count += 1
             self.update_count += 1
 
@@ -273,16 +283,6 @@ class ConversationStateManager:  # pylint: disable=too-many-instance-attributes
                         else:  # APPEND
                             setattr(self._execution_state, exec_field, value)
 
-            if self.enable_time_travel:
-                snapshot = StateSnapshot(
-                    state=self._full_state().to_dict(),
-                    timestamp=datetime.now(),
-                    node_id=node_id,
-                )
-                self._snapshots.append(snapshot)
-                if len(self._snapshots) > self.max_history_size:
-                    self._snapshots = self._snapshots[-self.max_history_size :]
-
             checkpoint_data_to_save: dict[str, Any] | None = None
             if (
                 self.checkpoint_dir