feat: add AgentMaxIterationError exc (#30423)

api/core/agent/cot_agent_runner.py

@@ -22,6 +22,7 @@ from core.prompt.agent_history_prompt_transform import AgentHistoryPromptTransfo
 from core.tools.__base.tool import Tool
 from core.tools.entities.tool_entities import ToolInvokeMeta
 from core.tools.tool_engine import ToolEngine
+from core.workflow.nodes.agent.exc import AgentMaxIterationError
 from models.model import Message
 
 logger = logging.getLogger(__name__)
@@ -165,6 +166,11 @@ class CotAgentRunner(BaseAgentRunner, ABC):
             scratchpad.thought = scratchpad.thought.strip() or "I am thinking about how to help you"
             self._agent_scratchpad.append(scratchpad)
 
+            # Check if max iteration is reached and model still wants to call tools
+            if iteration_step == max_iteration_steps and scratchpad.action:
+                if scratchpad.action.action_name.lower() != "final answer":
+                    raise AgentMaxIterationError(app_config.agent.max_iteration)
+
             # get llm usage
             if "usage" in usage_dict:
                 if usage_dict["usage"] is not None:

api/core/agent/fc_agent_runner.py

@@ -25,6 +25,7 @@ from core.model_runtime.entities.message_entities import ImagePromptMessageConte
 from core.prompt.agent_history_prompt_transform import AgentHistoryPromptTransform
 from core.tools.entities.tool_entities import ToolInvokeMeta
 from core.tools.tool_engine import ToolEngine
+from core.workflow.nodes.agent.exc import AgentMaxIterationError
 from models.model import Message
 
 logger = logging.getLogger(__name__)
@@ -222,6 +223,10 @@ class FunctionCallAgentRunner(BaseAgentRunner):
 
             final_answer += response + "\n"
 
+            # Check if max iteration is reached and model still wants to call tools
+            if iteration_step == max_iteration_steps and tool_calls:
+                raise AgentMaxIterationError(app_config.agent.max_iteration)
+
             # call tools
             tool_responses = []
             for tool_call_id, tool_call_name, tool_call_args in tool_calls:

api/core/workflow/nodes/agent/exc.py

@@ -119,3 +119,14 @@ class AgentVariableTypeError(AgentNodeError):
         self.expected_type = expected_type
         self.actual_type = actual_type
         super().__init__(message)
+
+
+class AgentMaxIterationError(AgentNodeError):
+    """Exception raised when the agent exceeds the maximum iteration limit."""
+
+    def __init__(self, max_iteration: int):
+        self.max_iteration = max_iteration
+        super().__init__(
+            f"Agent exceeded the maximum iteration limit of {max_iteration}. "
+            f"The agent was unable to complete the task within the allowed number of iterations."
+        )