Enhance conversation history and runtime variable management

- Update ConversationRecorder to include source and nodeId metadata in transcripts for better context tracking.
- Introduce optional variable handling in DynamicVariableStore, allowing for unset variables to be rendered as empty without raising errors.
- Refactor WorkflowBrain to apply turn configurations and manage interaction policies dynamically, improving agent responsiveness.
- Implement tests to ensure proper handling of updated session variables and workflow metadata in various scenarios.

backend/services/workflow_engine.py

@@ -23,6 +23,8 @@ class AgentStageConfig:
     knowledge_mode: str
     knowledge_top_n: int
     knowledge_score_threshold: float
+    enable_interrupt: bool
+    turn_config: dict[str, Any]
 
 
 class WorkflowEngine:
@@ -106,6 +108,12 @@ class WorkflowEngine:
         asr_key = "defaultAsrResourceId" if inherits_global else "asrResourceId"
         tts_key = "defaultTtsResourceId" if inherits_global else "ttsResourceId"
         knowledge_base_id = str(source.get("knowledgeBaseId") or "")
+        global_turn_config = self.settings.get("turnConfig")
+        if not isinstance(global_turn_config, dict):
+            global_turn_config = {}
+        turn_config = source.get("turnConfig", global_turn_config)
+        if not isinstance(turn_config, dict):
+            turn_config = global_turn_config
         return AgentStageConfig(
             inherits_global=inherits_global,
             llm_resource_id=str(source.get(llm_key) or ""),
@@ -122,6 +130,13 @@ class WorkflowEngine:
             knowledge_score_threshold=float(
                 source.get("knowledgeScoreThreshold") or 0.0
             ),
+            enable_interrupt=bool(
+                source.get(
+                    "enableInterrupt",
+                    self.settings.get("enableInterrupt", True),
+                )
+            ),
+            turn_config=dict(turn_config),
         )
 
     def prompt_for(self, node_id: str, store: DynamicVariableStore) -> str: