feat: Add conversation variable persistence layer (#30531)

api/core/app/layers/conversation_variable_persist_layer.py

@@ -0,0 +1,60 @@
+import logging
+
+from core.variables import Variable
+from core.workflow.constants import CONVERSATION_VARIABLE_NODE_ID
+from core.workflow.conversation_variable_updater import ConversationVariableUpdater
+from core.workflow.enums import NodeType
+from core.workflow.graph_engine.layers.base import GraphEngineLayer
+from core.workflow.graph_events import GraphEngineEvent, NodeRunSucceededEvent
+from core.workflow.nodes.variable_assigner.common import helpers as common_helpers
+
+logger = logging.getLogger(__name__)
+
+
+class ConversationVariablePersistenceLayer(GraphEngineLayer):
+    def __init__(self, conversation_variable_updater: ConversationVariableUpdater) -> None:
+        super().__init__()
+        self._conversation_variable_updater = conversation_variable_updater
+
+    def on_graph_start(self) -> None:
+        pass
+
+    def on_event(self, event: GraphEngineEvent) -> None:
+        if not isinstance(event, NodeRunSucceededEvent):
+            return
+        if event.node_type != NodeType.VARIABLE_ASSIGNER:
+            return
+        if self.graph_runtime_state is None:
+            return
+
+        updated_variables = common_helpers.get_updated_variables(event.node_run_result.process_data) or []
+        if not updated_variables:
+            return
+
+        conversation_id = self.graph_runtime_state.system_variable.conversation_id
+        if conversation_id is None:
+            return
+
+        updated_any = False
+        for item in updated_variables:
+            selector = item.selector
+            if len(selector) < 2:
+                logger.warning("Conversation variable selector invalid. selector=%s", selector)
+                continue
+            if selector[0] != CONVERSATION_VARIABLE_NODE_ID:
+                continue
+            variable = self.graph_runtime_state.variable_pool.get(selector)
+            if not isinstance(variable, Variable):
+                logger.warning(
+                    "Conversation variable not found in variable pool. selector=%s",
+                    selector,
+                )
+                continue
+            self._conversation_variable_updater.update(conversation_id=conversation_id, variable=variable)
+            updated_any = True
+
+        if updated_any:
+            self._conversation_variable_updater.flush()
+
+    def on_graph_end(self, error: Exception | None) -> None:
+        pass