1080 lines
53 KiB
Python
1080 lines
53 KiB
Python
import asyncio
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import uuid
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from typing import AsyncGenerator, Optional
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from opentelemetry.trace import Span
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from letta.adapters.letta_llm_adapter import LettaLLMAdapter
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from letta.adapters.simple_llm_request_adapter import SimpleLLMRequestAdapter
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from letta.adapters.simple_llm_stream_adapter import SimpleLLMStreamAdapter
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from letta.agents.helpers import (
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_build_rule_violation_result,
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_load_last_function_response,
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_maybe_get_approval_messages,
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_prepare_in_context_messages_no_persist_async,
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_safe_load_tool_call_str,
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generate_step_id,
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merge_and_validate_prefilled_args,
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)
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from letta.agents.letta_agent_v2 import LettaAgentV2
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from letta.constants import DEFAULT_MAX_STEPS, NON_USER_MSG_PREFIX, REQUEST_HEARTBEAT_PARAM
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from letta.errors import ContextWindowExceededError, LLMError
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from letta.helpers import ToolRulesSolver
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from letta.helpers.datetime_helpers import get_utc_time, get_utc_timestamp_ns
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from letta.helpers.tool_execution_helper import enable_strict_mode
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from letta.local_llm.constants import INNER_THOUGHTS_KWARG
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from letta.otel.tracing import trace_method
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from letta.schemas.agent import AgentState
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from letta.schemas.enums import MessageRole
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from letta.schemas.letta_message import LettaMessage, MessageType
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from letta.schemas.letta_message_content import OmittedReasoningContent, ReasoningContent, RedactedReasoningContent, TextContent
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from letta.schemas.letta_response import LettaResponse
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from letta.schemas.letta_stop_reason import LettaStopReason, StopReasonType
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from letta.schemas.message import Message, MessageCreate, ToolReturn
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from letta.schemas.openai.chat_completion_response import ToolCall, UsageStatistics
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from letta.schemas.step import StepProgression
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from letta.schemas.step_metrics import StepMetrics
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from letta.schemas.tool_execution_result import ToolExecutionResult
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from letta.server.rest_api.utils import (
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create_approval_request_message_from_llm_response,
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create_letta_messages_from_llm_response,
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create_parallel_tool_messages_from_llm_response,
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)
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from letta.services.helpers.tool_parser_helper import runtime_override_tool_json_schema
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from letta.settings import settings, summarizer_settings
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from letta.system import package_function_response
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from letta.utils import log_telemetry, validate_function_response
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class ToolCallDenial(ToolCall):
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reason: Optional[str] = None
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class LettaAgentV3(LettaAgentV2):
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"""
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Similar to V2, but stripped down / simplified, while also generalized:
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* Supports non-tool returns
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* No inner thoughts in kwargs
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* No heartbeats (loops happen on tool calls)
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TODOs:
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* Support tool rules
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* Support Gemini / OpenAI client
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"""
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def _initialize_state(self):
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super()._initialize_state()
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self._require_tool_call = False
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@trace_method
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async def step(
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self,
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input_messages: list[MessageCreate],
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max_steps: int = DEFAULT_MAX_STEPS,
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run_id: str | None = None,
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use_assistant_message: bool = True, # NOTE: not used
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include_return_message_types: list[MessageType] | None = None,
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request_start_timestamp_ns: int | None = None,
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) -> LettaResponse:
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"""
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Execute the agent loop in blocking mode, returning all messages at once.
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Args:
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input_messages: List of new messages to process
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max_steps: Maximum number of agent steps to execute
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run_id: Optional job/run ID for tracking
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use_assistant_message: Whether to use assistant message format
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include_return_message_types: Filter for which message types to return
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request_start_timestamp_ns: Start time for tracking request duration
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Returns:
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LettaResponse: Complete response with all messages and metadata
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"""
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self._initialize_state()
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request_span = self._request_checkpoint_start(request_start_timestamp_ns=request_start_timestamp_ns)
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in_context_messages, input_messages_to_persist = await _prepare_in_context_messages_no_persist_async(
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input_messages, self.agent_state, self.message_manager, self.actor, run_id
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)
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in_context_messages = in_context_messages + input_messages_to_persist
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response_letta_messages = []
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for i in range(max_steps):
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response = self._step(
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messages=in_context_messages + self.response_messages,
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input_messages_to_persist=input_messages_to_persist,
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# TODO need to support non-streaming adapter too
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llm_adapter=SimpleLLMRequestAdapter(llm_client=self.llm_client, llm_config=self.agent_state.llm_config),
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run_id=run_id,
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# use_assistant_message=use_assistant_message,
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include_return_message_types=include_return_message_types,
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request_start_timestamp_ns=request_start_timestamp_ns,
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)
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async for chunk in response:
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response_letta_messages.append(chunk)
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if not self.should_continue:
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break
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input_messages_to_persist = []
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# Rebuild context window after stepping
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if not self.agent_state.message_buffer_autoclear:
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await self.summarize_conversation_history(
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in_context_messages=in_context_messages,
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new_letta_messages=self.response_messages,
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total_tokens=self.usage.total_tokens,
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force=False,
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)
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if self.stop_reason is None:
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self.stop_reason = LettaStopReason(stop_reason=StopReasonType.end_turn.value)
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result = LettaResponse(messages=response_letta_messages, stop_reason=self.stop_reason, usage=self.usage)
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if run_id:
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if self.job_update_metadata is None:
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self.job_update_metadata = {}
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self.job_update_metadata["result"] = result.model_dump(mode="json")
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await self._request_checkpoint_finish(
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request_span=request_span, request_start_timestamp_ns=request_start_timestamp_ns, run_id=run_id
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)
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return result
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@trace_method
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async def stream(
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self,
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input_messages: list[MessageCreate],
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max_steps: int = DEFAULT_MAX_STEPS,
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stream_tokens: bool = False,
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run_id: str | None = None,
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use_assistant_message: bool = True, # NOTE: not used
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include_return_message_types: list[MessageType] | None = None,
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request_start_timestamp_ns: int | None = None,
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) -> AsyncGenerator[str, None]:
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"""
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Execute the agent loop in streaming mode, yielding chunks as they become available.
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If stream_tokens is True, individual tokens are streamed as they arrive from the LLM,
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providing the lowest latency experience, otherwise each complete step (reasoning +
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tool call + tool return) is yielded as it completes.
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Args:
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input_messages: List of new messages to process
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max_steps: Maximum number of agent steps to execute
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stream_tokens: Whether to stream back individual tokens. Not all llm
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providers offer native token streaming functionality; in these cases,
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this api streams back steps rather than individual tokens.
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run_id: Optional job/run ID for tracking
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use_assistant_message: Whether to use assistant message format
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include_return_message_types: Filter for which message types to return
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request_start_timestamp_ns: Start time for tracking request duration
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Yields:
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str: JSON-formatted SSE data chunks for each completed step
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"""
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self._initialize_state()
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request_span = self._request_checkpoint_start(request_start_timestamp_ns=request_start_timestamp_ns)
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first_chunk = True
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if stream_tokens:
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llm_adapter = SimpleLLMStreamAdapter(
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llm_client=self.llm_client,
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llm_config=self.agent_state.llm_config,
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run_id=run_id,
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)
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else:
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llm_adapter = SimpleLLMRequestAdapter(
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llm_client=self.llm_client,
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llm_config=self.agent_state.llm_config,
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)
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try:
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in_context_messages, input_messages_to_persist = await _prepare_in_context_messages_no_persist_async(
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input_messages, self.agent_state, self.message_manager, self.actor, run_id
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)
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in_context_messages = in_context_messages + input_messages_to_persist
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for i in range(max_steps):
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response = self._step(
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messages=in_context_messages + self.response_messages,
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input_messages_to_persist=input_messages_to_persist,
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llm_adapter=llm_adapter,
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run_id=run_id,
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# use_assistant_message=use_assistant_message,
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include_return_message_types=include_return_message_types,
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request_start_timestamp_ns=request_start_timestamp_ns,
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)
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async for chunk in response:
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if first_chunk:
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request_span = self._request_checkpoint_ttft(request_span, request_start_timestamp_ns)
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yield f"data: {chunk.model_dump_json()}\n\n"
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first_chunk = False
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if not self.should_continue:
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break
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input_messages_to_persist = []
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if not self.agent_state.message_buffer_autoclear:
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await self.summarize_conversation_history(
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in_context_messages=in_context_messages,
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new_letta_messages=self.response_messages,
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total_tokens=self.usage.total_tokens,
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force=False,
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)
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except:
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if self.stop_reason and not first_chunk:
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yield f"data: {self.stop_reason.model_dump_json()}\n\n"
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raise
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if run_id:
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letta_messages = Message.to_letta_messages_from_list(
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self.response_messages,
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use_assistant_message=False, # NOTE: set to false
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reverse=False,
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# text_is_assistant_message=(self.agent_state.agent_type == AgentType.react_agent),
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text_is_assistant_message=True,
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)
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result = LettaResponse(messages=letta_messages, stop_reason=self.stop_reason, usage=self.usage)
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if self.job_update_metadata is None:
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self.job_update_metadata = {}
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self.job_update_metadata["result"] = result.model_dump(mode="json")
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await self._request_checkpoint_finish(
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request_span=request_span, request_start_timestamp_ns=request_start_timestamp_ns, run_id=run_id
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)
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for finish_chunk in self.get_finish_chunks_for_stream(self.usage, self.stop_reason):
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yield f"data: {finish_chunk}\n\n"
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@trace_method
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async def _step(
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self,
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messages: list[Message],
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llm_adapter: LettaLLMAdapter,
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input_messages_to_persist: list[Message] | None = None,
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run_id: str | None = None,
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# use_assistant_message: bool = True,
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include_return_message_types: list[MessageType] | None = None,
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request_start_timestamp_ns: int | None = None,
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remaining_turns: int = -1,
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dry_run: bool = False,
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enforce_run_id_set: bool = True,
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) -> AsyncGenerator[LettaMessage | dict, None]:
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"""
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Execute a single agent step (one LLM call and tool execution).
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This is the core execution method that all public methods (step, stream_steps,
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stream_tokens) funnel through. It handles the complete flow of making an LLM
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request, processing the response, executing tools, and persisting messages.
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Args:
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messages: Current in-context messages
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llm_adapter: Adapter for LLM interaction (blocking or streaming)
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input_messages_to_persist: New messages to persist after execution
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run_id: Optional job/run ID for tracking
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include_return_message_types: Filter for which message types to yield
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request_start_timestamp_ns: Start time for tracking request duration
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remaining_turns: Number of turns remaining (for max_steps enforcement)
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dry_run: If true, only build and return the request without executing
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Yields:
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LettaMessage or dict: Chunks for streaming mode, or request data for dry_run
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"""
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if enforce_run_id_set and run_id is None:
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raise AssertionError("run_id is required when enforce_run_id_set is True")
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step_progression = StepProgression.START
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# TODO(@caren): clean this up
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tool_calls, content, agent_step_span, first_chunk, step_id, logged_step, step_start_ns, step_metrics = (
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None,
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None,
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None,
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None,
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None,
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None,
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None,
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None,
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)
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try:
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self.last_function_response = _load_last_function_response(messages)
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valid_tools = await self._get_valid_tools()
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require_tool_call = self.tool_rules_solver.should_force_tool_call()
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if self._require_tool_call != require_tool_call:
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if require_tool_call:
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self.logger.info("switching to constrained mode (forcing tool call)")
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else:
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self.logger.info("switching to unconstrained mode (allowing non-tool responses)")
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self._require_tool_call = require_tool_call
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approval_request, approval_response = _maybe_get_approval_messages(messages)
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tool_call_denials, tool_returns = [], []
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if approval_request and approval_response:
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content = approval_request.content
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# Get tool calls that are pending
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backfill_tool_call_id = approval_request.tool_calls[0].id # legacy case
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pending_tool_calls = {
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backfill_tool_call_id if a.tool_call_id.startswith("message-") else a.tool_call_id: a
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for a in approval_response.approvals
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if a.type == "approval" and a.approve
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}
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tool_calls = [t for t in approval_request.tool_calls if t.id in pending_tool_calls]
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# Get tool calls that were denied
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denies = {d.tool_call_id: d for d in approval_response.approvals if d.type == "approval" and not d.approve}
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tool_call_denials = [
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ToolCallDenial(**t.model_dump(), reason=denies.get(t.id).reason) for t in approval_request.tool_calls if t.id in denies
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]
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# Get tool calls that were executed client side
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if approval_response.approvals:
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tool_returns = [r for r in approval_response.approvals if r.type == "tool"]
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step_id = approval_request.step_id
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step_metrics = await self.step_manager.get_step_metrics_async(step_id=step_id, actor=self.actor)
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else:
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# Check for job cancellation at the start of each step
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if run_id and await self._check_run_cancellation(run_id):
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self.should_continue = False
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self.stop_reason = LettaStopReason(stop_reason=StopReasonType.cancelled.value)
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self.logger.info(f"Agent execution cancelled for run {run_id}")
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return
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step_id = generate_step_id()
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step_progression, logged_step, step_metrics, agent_step_span = await self._step_checkpoint_start(
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step_id=step_id, run_id=run_id
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)
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messages = await self._refresh_messages(messages)
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force_tool_call = valid_tools[0]["name"] if len(valid_tools) == 1 and self._require_tool_call else None
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for llm_request_attempt in range(summarizer_settings.max_summarizer_retries + 1):
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try:
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request_data = self.llm_client.build_request_data(
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agent_type=self.agent_state.agent_type,
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messages=messages,
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llm_config=self.agent_state.llm_config,
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tools=valid_tools,
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force_tool_call=force_tool_call,
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requires_subsequent_tool_call=self._require_tool_call,
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)
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# TODO: Extend to more providers, and also approval tool rules
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# Enable Anthropic parallel tool use when no tool rules are attached
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try:
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if self.agent_state.llm_config.model_endpoint_type in ["anthropic", "bedrock"]:
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no_tool_rules = not self.agent_state.tool_rules or len(self.agent_state.tool_rules) == 0
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requires_approval = self.tool_rules_solver.get_requires_approval_tools(
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set([t["name"] for t in valid_tools])
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)
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has_approval_tools = len(requires_approval) > 0
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if (
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isinstance(request_data.get("tool_choice"), dict)
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and "disable_parallel_tool_use" in request_data["tool_choice"]
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):
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# Gate parallel tool use on both: no tool rules and no approval-required tools
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if no_tool_rules and not has_approval_tools:
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request_data["tool_choice"]["disable_parallel_tool_use"] = False
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else:
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# Explicitly disable when approvals exist (TODO support later) or tool rules present
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request_data["tool_choice"]["disable_parallel_tool_use"] = True
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except Exception:
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# if this fails, we simply don't enable parallel tool use
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pass
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if dry_run:
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yield request_data
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return
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step_progression, step_metrics = self._step_checkpoint_llm_request_start(step_metrics, agent_step_span)
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invocation = llm_adapter.invoke_llm(
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request_data=request_data,
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messages=messages,
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tools=valid_tools,
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use_assistant_message=False, # NOTE: set to false
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requires_approval_tools=self.tool_rules_solver.get_requires_approval_tools(
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set([t["name"] for t in valid_tools])
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),
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step_id=step_id,
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actor=self.actor,
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)
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async for chunk in invocation:
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if llm_adapter.supports_token_streaming():
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if include_return_message_types is None or chunk.message_type in include_return_message_types:
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first_chunk = True
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yield chunk
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# If you've reached this point without an error, break out of retry loop
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break
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except ValueError as e:
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self.stop_reason = LettaStopReason(stop_reason=StopReasonType.invalid_llm_response.value)
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raise e
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except LLMError as e:
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self.stop_reason = LettaStopReason(stop_reason=StopReasonType.llm_api_error.value)
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raise e
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except Exception as e:
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if isinstance(e, ContextWindowExceededError) and llm_request_attempt < summarizer_settings.max_summarizer_retries:
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# Retry case
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messages = await self.summarize_conversation_history(
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in_context_messages=messages,
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new_letta_messages=self.response_messages,
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llm_config=self.agent_state.llm_config,
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force=True,
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)
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else:
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raise e
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step_progression, step_metrics = self._step_checkpoint_llm_request_finish(
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step_metrics, agent_step_span, llm_adapter.llm_request_finish_timestamp_ns
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)
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self._update_global_usage_stats(llm_adapter.usage)
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# Handle the AI response with the extracted data (supports multiple tool calls)
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# Gather tool calls. Approval paths specify a single tool call.
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if hasattr(llm_adapter, "tool_calls") and llm_adapter.tool_calls:
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tool_calls = llm_adapter.tool_calls
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elif llm_adapter.tool_call is not None:
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tool_calls = [llm_adapter.tool_call]
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aggregated_persisted: list[Message] = []
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persisted_messages, self.should_continue, self.stop_reason = await self._handle_ai_response(
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tool_calls=tool_calls,
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valid_tool_names=[tool["name"] for tool in valid_tools],
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agent_state=self.agent_state,
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tool_rules_solver=self.tool_rules_solver,
|
||
usage=UsageStatistics(
|
||
completion_tokens=self.usage.completion_tokens,
|
||
prompt_tokens=self.usage.prompt_tokens,
|
||
total_tokens=self.usage.total_tokens,
|
||
),
|
||
content=content or llm_adapter.content,
|
||
pre_computed_assistant_message_id=llm_adapter.message_id,
|
||
step_id=step_id,
|
||
initial_messages=input_messages_to_persist,
|
||
agent_step_span=agent_step_span,
|
||
is_final_step=(remaining_turns == 0),
|
||
run_id=run_id,
|
||
step_metrics=step_metrics,
|
||
is_approval=approval_response is not None,
|
||
tool_call_denials=tool_call_denials,
|
||
tool_return=tool_returns[0] if tool_returns else None,
|
||
)
|
||
aggregated_persisted.extend(persisted_messages)
|
||
# NOTE: there is an edge case where persisted_messages is empty (the LLM did a "no-op")
|
||
|
||
new_message_idx = len(input_messages_to_persist) if input_messages_to_persist else 0
|
||
self.response_messages.extend(aggregated_persisted[new_message_idx:])
|
||
|
||
if llm_adapter.supports_token_streaming():
|
||
# Stream each tool return if tools were executed
|
||
response_tool_returns = [msg for msg in aggregated_persisted if msg.role == "tool"]
|
||
for tr in response_tool_returns:
|
||
# Skip streaming for aggregated parallel tool returns (no per-call tool_call_id)
|
||
if tr.tool_call_id is None and tr.tool_returns:
|
||
continue
|
||
tool_return_letta = tr.to_letta_messages()[0]
|
||
if include_return_message_types is None or tool_return_letta.message_type in include_return_message_types:
|
||
yield tool_return_letta
|
||
else:
|
||
filter_user_messages = [m for m in aggregated_persisted[new_message_idx:] if m.role != "user"]
|
||
letta_messages = Message.to_letta_messages_from_list(
|
||
filter_user_messages,
|
||
use_assistant_message=False, # NOTE: set to false
|
||
reverse=False,
|
||
# text_is_assistant_message=(self.agent_state.agent_type == AgentType.react_agent),
|
||
text_is_assistant_message=True,
|
||
)
|
||
for message in letta_messages:
|
||
if include_return_message_types is None or message.message_type in include_return_message_types:
|
||
yield message
|
||
|
||
# Persist approval responses immediately to prevent agent from getting into a bad state
|
||
if (
|
||
len(input_messages_to_persist) == 1
|
||
and input_messages_to_persist[0].role == "approval"
|
||
and persisted_messages[0].role == "approval"
|
||
and persisted_messages[1].role == "tool"
|
||
):
|
||
self.agent_state.message_ids = self.agent_state.message_ids + [m.id for m in persisted_messages[:2]]
|
||
await self.agent_manager.update_message_ids_async(
|
||
agent_id=self.agent_state.id, message_ids=self.agent_state.message_ids, actor=self.actor
|
||
)
|
||
# TODO should we be logging this even if persisted_messages is empty? Technically, there still was an LLM call
|
||
step_progression, step_metrics = await self._step_checkpoint_finish(step_metrics, agent_step_span, logged_step)
|
||
except Exception as e:
|
||
import traceback
|
||
|
||
self.logger.warning(f"Error during step processing: {e}")
|
||
self.job_update_metadata = {"error": str(e)}
|
||
|
||
# This indicates we failed after we decided to stop stepping, which indicates a bug with our flow.
|
||
if not self.stop_reason:
|
||
self.stop_reason = LettaStopReason(stop_reason=StopReasonType.error.value)
|
||
elif self.stop_reason.stop_reason in (StopReasonType.end_turn, StopReasonType.max_steps, StopReasonType.tool_rule):
|
||
self.logger.error("Error occurred during step processing, with valid stop reason: %s", self.stop_reason.stop_reason)
|
||
elif self.stop_reason.stop_reason not in (
|
||
StopReasonType.no_tool_call,
|
||
StopReasonType.invalid_tool_call,
|
||
StopReasonType.invalid_llm_response,
|
||
StopReasonType.llm_api_error,
|
||
):
|
||
self.logger.error("Error occurred during step processing, with unexpected stop reason: %s", self.stop_reason.stop_reason)
|
||
raise e
|
||
finally:
|
||
self.logger.debug("Running cleanup for agent loop run: %s", run_id)
|
||
self.logger.info("Running final update. Step Progression: %s", step_progression)
|
||
try:
|
||
if step_progression == StepProgression.FINISHED:
|
||
if not self.should_continue:
|
||
if self.stop_reason is None:
|
||
self.stop_reason = LettaStopReason(stop_reason=StopReasonType.end_turn.value)
|
||
if logged_step and step_id:
|
||
await self.step_manager.update_step_stop_reason(self.actor, step_id, self.stop_reason.stop_reason)
|
||
return
|
||
if step_progression < StepProgression.STEP_LOGGED:
|
||
# Error occurred before step was fully logged
|
||
import traceback
|
||
|
||
if logged_step:
|
||
await self.step_manager.update_step_error_async(
|
||
actor=self.actor,
|
||
step_id=step_id, # Use original step_id for telemetry
|
||
error_type=type(e).__name__ if "e" in locals() else "Unknown",
|
||
error_message=str(e) if "e" in locals() else "Unknown error",
|
||
error_traceback=traceback.format_exc(),
|
||
stop_reason=self.stop_reason,
|
||
)
|
||
if step_progression <= StepProgression.STREAM_RECEIVED:
|
||
if first_chunk and settings.track_errored_messages and input_messages_to_persist:
|
||
for message in input_messages_to_persist:
|
||
message.is_err = True
|
||
message.step_id = step_id
|
||
message.run_id = run_id
|
||
await self.message_manager.create_many_messages_async(
|
||
input_messages_to_persist,
|
||
actor=self.actor,
|
||
run_id=run_id,
|
||
project_id=self.agent_state.project_id,
|
||
template_id=self.agent_state.template_id,
|
||
)
|
||
elif step_progression <= StepProgression.LOGGED_TRACE:
|
||
if self.stop_reason is None:
|
||
self.logger.error("Error in step after logging step")
|
||
self.stop_reason = LettaStopReason(stop_reason=StopReasonType.error.value)
|
||
if logged_step:
|
||
await self.step_manager.update_step_stop_reason(self.actor, step_id, self.stop_reason.stop_reason)
|
||
else:
|
||
self.logger.error("Invalid StepProgression value")
|
||
|
||
# Do tracking for failure cases. Can consolidate with success conditions later.
|
||
if settings.track_stop_reason:
|
||
await self._log_request(request_start_timestamp_ns, None, self.job_update_metadata, is_error=True, run_id=run_id)
|
||
|
||
# Record partial step metrics on failure (capture whatever timing data we have)
|
||
if logged_step and step_metrics and step_progression < StepProgression.FINISHED:
|
||
# Calculate total step time up to the failure point
|
||
step_metrics.step_ns = get_utc_timestamp_ns() - step_metrics.step_start_ns
|
||
|
||
await self._record_step_metrics(
|
||
step_id=step_id,
|
||
step_metrics=step_metrics,
|
||
run_id=run_id,
|
||
)
|
||
except Exception as e:
|
||
self.logger.error(f"Error during post-completion step tracking: {e}")
|
||
|
||
@trace_method
|
||
async def _handle_ai_response(
|
||
self,
|
||
valid_tool_names: list[str],
|
||
agent_state: AgentState,
|
||
tool_rules_solver: ToolRulesSolver,
|
||
usage: UsageStatistics,
|
||
content: list[TextContent | ReasoningContent | RedactedReasoningContent | OmittedReasoningContent] | None = None,
|
||
pre_computed_assistant_message_id: str | None = None,
|
||
step_id: str | None = None,
|
||
initial_messages: list[Message] | None = None,
|
||
agent_step_span: Span | None = None,
|
||
is_final_step: bool | None = None,
|
||
run_id: str | None = None,
|
||
step_metrics: StepMetrics = None,
|
||
is_approval: bool | None = None,
|
||
tool_calls: list[ToolCall] = [],
|
||
tool_call_denials: list[ToolCallDenial] = [],
|
||
tool_return: ToolReturn | None = None,
|
||
) -> tuple[list[Message], bool, LettaStopReason | None]:
|
||
"""
|
||
Handle the final AI response once streaming completes, execute / validate tool calls,
|
||
decide whether we should keep stepping, and persist state.
|
||
|
||
Unified approach: treats single and multi-tool calls uniformly to reduce code duplication.
|
||
"""
|
||
first_tool_call = tool_calls[0] if tool_calls else None
|
||
|
||
if tool_return is not None:
|
||
continue_stepping = True
|
||
stop_reason = None
|
||
tool_call_messages = [
|
||
Message(
|
||
role=MessageRole.tool,
|
||
content=[TextContent(text=tool_return.func_response)],
|
||
agent_id=agent_state.id,
|
||
model=agent_state.llm_config.model,
|
||
tool_calls=[],
|
||
tool_call_id=tool_return.tool_call_id,
|
||
created_at=get_utc_time(),
|
||
tool_returns=[tool_return],
|
||
run_id=run_id,
|
||
step_id=step_id,
|
||
)
|
||
]
|
||
messages_to_persist = (initial_messages or []) + tool_call_messages
|
||
for message in messages_to_persist:
|
||
if message.run_id is None:
|
||
message.run_id = run_id
|
||
|
||
persisted_messages = await self.message_manager.create_many_messages_async(
|
||
messages_to_persist,
|
||
actor=self.actor,
|
||
run_id=run_id,
|
||
project_id=agent_state.project_id,
|
||
template_id=agent_state.template_id,
|
||
)
|
||
return persisted_messages, continue_stepping, stop_reason
|
||
|
||
# Handle denial case first (special case that bypasses normal flow)
|
||
if tool_call_denials:
|
||
assert len(tool_call_denials) == 1, "Only one tool call denial is supported"
|
||
tool_call_denial = tool_call_denials[0]
|
||
continue_stepping = True
|
||
stop_reason = None
|
||
tool_call_messages = create_letta_messages_from_llm_response(
|
||
agent_id=agent_state.id,
|
||
model=agent_state.llm_config.model,
|
||
function_name=tool_call_denial.function.name,
|
||
function_arguments={},
|
||
tool_execution_result=ToolExecutionResult(status="error"),
|
||
tool_call_id=tool_call_denial.id or f"call_{uuid.uuid4().hex[:8]}",
|
||
function_response=f"Error: request to call tool denied. User reason: {tool_call_denial.reason}",
|
||
timezone=agent_state.timezone,
|
||
continue_stepping=continue_stepping,
|
||
heartbeat_reason=f"{NON_USER_MSG_PREFIX}Continuing: user denied request to call tool.",
|
||
reasoning_content=None,
|
||
pre_computed_assistant_message_id=None,
|
||
step_id=step_id,
|
||
run_id=run_id,
|
||
is_approval_response=True,
|
||
force_set_request_heartbeat=False,
|
||
add_heartbeat_on_continue=False,
|
||
)
|
||
messages_to_persist = (initial_messages or []) + tool_call_messages
|
||
|
||
# Set run_id on all messages before persisting
|
||
for message in messages_to_persist:
|
||
if message.run_id is None:
|
||
message.run_id = run_id
|
||
|
||
persisted_messages = await self.message_manager.create_many_messages_async(
|
||
messages_to_persist,
|
||
actor=self.actor,
|
||
run_id=run_id,
|
||
project_id=agent_state.project_id,
|
||
template_id=agent_state.template_id,
|
||
)
|
||
return persisted_messages, continue_stepping, stop_reason
|
||
|
||
# 3. Handle no-tool cases (content-only or no-op)
|
||
if not tool_calls:
|
||
# Case 3a: No tool call, no content (LLM no-op)
|
||
if content is None or len(content) == 0:
|
||
# Check if there are required-before-exit tools that haven't been called
|
||
uncalled = tool_rules_solver.get_uncalled_required_tools(available_tools=set([t.name for t in agent_state.tools]))
|
||
if uncalled:
|
||
heartbeat_reason = (
|
||
f"{NON_USER_MSG_PREFIX}ToolRuleViolated: You must call {', '.join(uncalled)} at least once to exit the loop."
|
||
)
|
||
from letta.server.rest_api.utils import create_heartbeat_system_message
|
||
|
||
heartbeat_msg = create_heartbeat_system_message(
|
||
agent_id=agent_state.id,
|
||
model=agent_state.llm_config.model,
|
||
function_call_success=True,
|
||
timezone=agent_state.timezone,
|
||
heartbeat_reason=heartbeat_reason,
|
||
run_id=run_id,
|
||
)
|
||
messages_to_persist = (initial_messages or []) + [heartbeat_msg]
|
||
continue_stepping, stop_reason = True, None
|
||
else:
|
||
# No required tools remaining, end turn without persisting no-op
|
||
continue_stepping = False
|
||
stop_reason = LettaStopReason(stop_reason=StopReasonType.end_turn.value)
|
||
messages_to_persist = initial_messages or []
|
||
|
||
# Case 3b: No tool call but has content
|
||
else:
|
||
continue_stepping, heartbeat_reason, stop_reason = self._decide_continuation(
|
||
agent_state=agent_state,
|
||
tool_call_name=None,
|
||
tool_rule_violated=False,
|
||
tool_rules_solver=tool_rules_solver,
|
||
is_final_step=is_final_step,
|
||
)
|
||
assistant_message = create_letta_messages_from_llm_response(
|
||
agent_id=agent_state.id,
|
||
model=agent_state.llm_config.model,
|
||
function_name=None,
|
||
function_arguments=None,
|
||
tool_execution_result=None,
|
||
tool_call_id=None,
|
||
function_response=None,
|
||
timezone=agent_state.timezone,
|
||
continue_stepping=continue_stepping,
|
||
heartbeat_reason=heartbeat_reason,
|
||
reasoning_content=content,
|
||
pre_computed_assistant_message_id=pre_computed_assistant_message_id,
|
||
step_id=step_id,
|
||
run_id=run_id,
|
||
is_approval_response=is_approval,
|
||
force_set_request_heartbeat=False,
|
||
add_heartbeat_on_continue=bool(heartbeat_reason),
|
||
)
|
||
messages_to_persist = (initial_messages or []) + assistant_message
|
||
|
||
# Persist messages for no-tool cases
|
||
for message in messages_to_persist:
|
||
if message.run_id is None:
|
||
message.run_id = run_id
|
||
|
||
persisted_messages = await self.message_manager.create_many_messages_async(
|
||
messages_to_persist, actor=self.actor, run_id=run_id, project_id=agent_state.project_id, template_id=agent_state.template_id
|
||
)
|
||
return persisted_messages, continue_stepping, stop_reason
|
||
|
||
# 4. Unified tool execution path (works for both single and multiple tools)
|
||
|
||
# 4a. Check for single tool approval case (special handling required)
|
||
if len(tool_calls) == 1 and not is_approval:
|
||
single_tool = tool_calls[0]
|
||
tool_name = single_tool.function.name
|
||
tool_args = _safe_load_tool_call_str(single_tool.function.arguments)
|
||
tool_args.pop(REQUEST_HEARTBEAT_PARAM, None)
|
||
tool_args.pop(INNER_THOUGHTS_KWARG, None)
|
||
|
||
if tool_rules_solver.is_requires_approval_tool(tool_name):
|
||
tool_call_id = single_tool.id or f"call_{uuid.uuid4().hex[:8]}"
|
||
approval_message = create_approval_request_message_from_llm_response(
|
||
agent_id=agent_state.id,
|
||
model=agent_state.llm_config.model,
|
||
function_name=tool_name,
|
||
function_arguments=tool_args,
|
||
tool_call_id=tool_call_id,
|
||
actor=self.actor,
|
||
continue_stepping=True,
|
||
reasoning_content=content,
|
||
pre_computed_assistant_message_id=pre_computed_assistant_message_id,
|
||
step_id=step_id,
|
||
run_id=run_id,
|
||
append_request_heartbeat=False,
|
||
)
|
||
messages_to_persist = (initial_messages or []) + [approval_message]
|
||
|
||
for message in messages_to_persist:
|
||
if message.run_id is None:
|
||
message.run_id = run_id
|
||
|
||
persisted_messages = await self.message_manager.create_many_messages_async(
|
||
messages_to_persist,
|
||
actor=self.actor,
|
||
run_id=run_id,
|
||
project_id=agent_state.project_id,
|
||
template_id=agent_state.template_id,
|
||
)
|
||
return persisted_messages, False, LettaStopReason(stop_reason=StopReasonType.requires_approval.value)
|
||
|
||
# 4b. Validate parallel tool calling constraints
|
||
if len(tool_calls) > 1:
|
||
# No parallel tool calls with tool rules
|
||
if agent_state.tool_rules and len(agent_state.tool_rules) > 0:
|
||
raise ValueError(
|
||
"Parallel tool calling is not allowed when tool rules are present. Disable tool rules to use parallel tool calls."
|
||
)
|
||
# No parallel tool calls with approval-required tools
|
||
if any(tool_rules_solver.is_requires_approval_tool(tc.function.name) for tc in tool_calls):
|
||
raise ValueError("Parallel tool calling is not allowed when any tool requires approval.")
|
||
|
||
# 4c. Prepare execution specs for all tools
|
||
exec_specs = []
|
||
for tc in tool_calls:
|
||
call_id = tc.id or f"call_{uuid.uuid4().hex[:8]}"
|
||
name = tc.function.name
|
||
args = _safe_load_tool_call_str(tc.function.arguments)
|
||
args.pop(REQUEST_HEARTBEAT_PARAM, None)
|
||
args.pop(INNER_THOUGHTS_KWARG, None)
|
||
|
||
# Validate against allowed tools
|
||
tool_rule_violated = name not in valid_tool_names and not is_approval
|
||
|
||
# Handle prefilled args if present
|
||
if not tool_rule_violated:
|
||
prefill_args = tool_rules_solver.last_prefilled_args_by_tool.get(name)
|
||
if prefill_args:
|
||
target_tool = next((t for t in agent_state.tools if t.name == name), None)
|
||
provenance = tool_rules_solver.last_prefilled_args_provenance.get(name)
|
||
try:
|
||
args = merge_and_validate_prefilled_args(
|
||
tool=target_tool,
|
||
llm_args=args,
|
||
prefilled_args=prefill_args,
|
||
)
|
||
except ValueError as ve:
|
||
# Invalid prefilled args - create error result
|
||
error_prefix = "Invalid prefilled tool arguments from tool rules"
|
||
prov_suffix = f" (source={provenance})" if provenance else ""
|
||
err_msg = f"{error_prefix}{prov_suffix}: {str(ve)}"
|
||
|
||
exec_specs.append(
|
||
{
|
||
"id": call_id,
|
||
"name": name,
|
||
"args": args,
|
||
"violated": False,
|
||
"error": err_msg,
|
||
}
|
||
)
|
||
continue
|
||
|
||
exec_specs.append(
|
||
{
|
||
"id": call_id,
|
||
"name": name,
|
||
"args": args,
|
||
"violated": tool_rule_violated,
|
||
"error": None,
|
||
}
|
||
)
|
||
|
||
# 4d. Execute tools (sequentially for single, parallel for multiple)
|
||
if len(exec_specs) == 1:
|
||
# Single tool - execute directly without asyncio.gather overhead
|
||
spec = exec_specs[0]
|
||
if spec.get("error"):
|
||
# Prefill arg validation error
|
||
result = ToolExecutionResult(status="error", func_return=spec["error"])
|
||
exec_time = 0
|
||
elif spec["violated"]:
|
||
result = _build_rule_violation_result(spec["name"], valid_tool_names, tool_rules_solver)
|
||
exec_time = 0
|
||
else:
|
||
t0 = get_utc_timestamp_ns()
|
||
result = await self._execute_tool(
|
||
tool_name=spec["name"],
|
||
tool_args=spec["args"],
|
||
agent_state=agent_state,
|
||
agent_step_span=agent_step_span,
|
||
step_id=step_id,
|
||
)
|
||
exec_time = get_utc_timestamp_ns() - t0
|
||
results = [(result, exec_time)]
|
||
else:
|
||
# Multiple tools - execute in parallel
|
||
async def _run_one(spec):
|
||
if spec.get("error"):
|
||
return ToolExecutionResult(status="error", func_return=spec["error"]), 0
|
||
if spec["violated"]:
|
||
result = _build_rule_violation_result(spec["name"], valid_tool_names, tool_rules_solver)
|
||
return result, 0
|
||
t0 = get_utc_timestamp_ns()
|
||
res = await self._execute_tool(
|
||
tool_name=spec["name"],
|
||
tool_args=spec["args"],
|
||
agent_state=agent_state,
|
||
agent_step_span=agent_step_span,
|
||
step_id=step_id,
|
||
)
|
||
dt = get_utc_timestamp_ns() - t0
|
||
return res, dt
|
||
|
||
results = await asyncio.gather(*[_run_one(s) for s in exec_specs])
|
||
|
||
# Update metrics with execution time
|
||
if step_metrics is not None and results:
|
||
step_metrics.tool_execution_ns = max(dt for _, dt in results)
|
||
|
||
# 4e. Process results and compute function responses
|
||
function_responses: list[Optional[str]] = []
|
||
persisted_continue_flags: list[bool] = []
|
||
persisted_stop_reasons: list[LettaStopReason | None] = []
|
||
|
||
for idx, spec in enumerate(exec_specs):
|
||
tool_execution_result, _ = results[idx]
|
||
has_prefill_error = bool(spec.get("error"))
|
||
|
||
# Validate and format function response
|
||
truncate = spec["name"] not in {"conversation_search", "conversation_search_date", "archival_memory_search"}
|
||
return_char_limit = next((t.return_char_limit for t in agent_state.tools if t.name == spec["name"]), None)
|
||
function_response_string = validate_function_response(
|
||
tool_execution_result.func_return,
|
||
return_char_limit=return_char_limit,
|
||
truncate=truncate,
|
||
)
|
||
function_responses.append(function_response_string)
|
||
|
||
# Update last function response (for tool rules)
|
||
self.last_function_response = package_function_response(
|
||
was_success=tool_execution_result.success_flag,
|
||
response_string=function_response_string,
|
||
timezone=agent_state.timezone,
|
||
)
|
||
|
||
# Register successful tool call with solver
|
||
if not spec["violated"] and not has_prefill_error:
|
||
tool_rules_solver.register_tool_call(spec["name"])
|
||
|
||
# Decide continuation for this tool
|
||
if has_prefill_error:
|
||
cont = False
|
||
hb_reason = None
|
||
sr = LettaStopReason(stop_reason=StopReasonType.invalid_tool_call.value)
|
||
else:
|
||
cont, hb_reason, sr = self._decide_continuation(
|
||
agent_state=agent_state,
|
||
tool_call_name=spec["name"],
|
||
tool_rule_violated=spec["violated"],
|
||
tool_rules_solver=tool_rules_solver,
|
||
is_final_step=(is_final_step and idx == len(exec_specs) - 1),
|
||
)
|
||
persisted_continue_flags.append(cont)
|
||
persisted_stop_reasons.append(sr)
|
||
|
||
# 4f. Create messages using parallel message creation (works for both single and multi)
|
||
tool_call_specs = [{"name": s["name"], "arguments": s["args"], "id": s["id"]} for s in exec_specs]
|
||
tool_execution_results = [res for (res, _) in results]
|
||
|
||
# Use the parallel message creation function for both single and multiple tools
|
||
parallel_messages = create_parallel_tool_messages_from_llm_response(
|
||
agent_id=agent_state.id,
|
||
model=agent_state.llm_config.model,
|
||
tool_call_specs=tool_call_specs,
|
||
tool_execution_results=tool_execution_results,
|
||
function_responses=function_responses,
|
||
timezone=agent_state.timezone,
|
||
run_id=run_id,
|
||
step_id=step_id,
|
||
reasoning_content=content,
|
||
pre_computed_assistant_message_id=pre_computed_assistant_message_id,
|
||
is_approval_response=is_approval,
|
||
)
|
||
|
||
messages_to_persist: list[Message] = (initial_messages or []) + parallel_messages
|
||
|
||
# Set run_id on all messages before persisting
|
||
for message in messages_to_persist:
|
||
if message.run_id is None:
|
||
message.run_id = run_id
|
||
|
||
# Persist all messages
|
||
persisted_messages = await self.message_manager.create_many_messages_async(
|
||
messages_to_persist,
|
||
actor=self.actor,
|
||
run_id=run_id,
|
||
project_id=agent_state.project_id,
|
||
template_id=agent_state.template_id,
|
||
)
|
||
|
||
# 4g. Aggregate continuation decisions
|
||
# For multiple tools: continue if ANY says continue, use last non-None stop_reason
|
||
# For single tool: use its decision directly
|
||
aggregate_continue = any(persisted_continue_flags) if persisted_continue_flags else False
|
||
aggregate_stop_reason = None
|
||
for sr in persisted_stop_reasons:
|
||
if sr is not None:
|
||
aggregate_stop_reason = sr
|
||
|
||
return persisted_messages, aggregate_continue, aggregate_stop_reason
|
||
|
||
@trace_method
|
||
def _decide_continuation(
|
||
self,
|
||
agent_state: AgentState,
|
||
tool_call_name: Optional[str],
|
||
tool_rule_violated: bool,
|
||
tool_rules_solver: ToolRulesSolver,
|
||
is_final_step: bool | None,
|
||
) -> tuple[bool, str | None, LettaStopReason | None]:
|
||
"""
|
||
In v3 loop, we apply the following rules:
|
||
|
||
1. Did not call a tool? Loop ends
|
||
|
||
2. Called a tool? Loop continues. This can be:
|
||
2a. Called tool, tool executed successfully
|
||
2b. Called tool, tool failed to execute
|
||
2c. Called tool + tool rule violation (did not execute)
|
||
|
||
"""
|
||
continue_stepping = True # Default continue
|
||
continuation_reason: str | None = None
|
||
stop_reason: LettaStopReason | None = None
|
||
|
||
if tool_call_name is None:
|
||
# No tool call – if there are required-before-exit tools uncalled, keep stepping
|
||
# and provide explicit feedback to the model; otherwise end the loop.
|
||
uncalled = tool_rules_solver.get_uncalled_required_tools(available_tools=set([t.name for t in agent_state.tools]))
|
||
if uncalled and not is_final_step:
|
||
reason = f"{NON_USER_MSG_PREFIX}ToolRuleViolated: You must call {', '.join(uncalled)} at least once to exit the loop."
|
||
return True, reason, None
|
||
# No required tools remaining → end turn
|
||
return False, None, LettaStopReason(stop_reason=StopReasonType.end_turn.value)
|
||
else:
|
||
if tool_rule_violated:
|
||
continue_stepping = True
|
||
continuation_reason = f"{NON_USER_MSG_PREFIX}Continuing: tool rule violation."
|
||
else:
|
||
tool_rules_solver.register_tool_call(tool_call_name)
|
||
|
||
if tool_rules_solver.is_terminal_tool(tool_call_name):
|
||
stop_reason = LettaStopReason(stop_reason=StopReasonType.tool_rule.value)
|
||
continue_stepping = False
|
||
|
||
elif tool_rules_solver.has_children_tools(tool_call_name):
|
||
continue_stepping = True
|
||
continuation_reason = f"{NON_USER_MSG_PREFIX}Continuing: child tool rule."
|
||
|
||
elif tool_rules_solver.is_continue_tool(tool_call_name):
|
||
continue_stepping = True
|
||
continuation_reason = f"{NON_USER_MSG_PREFIX}Continuing: continue tool rule."
|
||
|
||
# – hard stop overrides –
|
||
if is_final_step:
|
||
continue_stepping = False
|
||
stop_reason = LettaStopReason(stop_reason=StopReasonType.max_steps.value)
|
||
else:
|
||
uncalled = tool_rules_solver.get_uncalled_required_tools(available_tools=set([t.name for t in agent_state.tools]))
|
||
if uncalled:
|
||
continue_stepping = True
|
||
continuation_reason = (
|
||
f"{NON_USER_MSG_PREFIX}Continuing, user expects these tools: [{', '.join(uncalled)}] to be called still."
|
||
)
|
||
|
||
stop_reason = None # reset – we’re still going
|
||
|
||
return continue_stepping, continuation_reason, stop_reason
|
||
|
||
@trace_method
|
||
async def _get_valid_tools(self):
|
||
tools = self.agent_state.tools
|
||
valid_tool_names = self.tool_rules_solver.get_allowed_tool_names(
|
||
available_tools=set([t.name for t in tools]),
|
||
last_function_response=self.last_function_response,
|
||
error_on_empty=False, # Return empty list instead of raising error
|
||
) or list(set(t.name for t in tools))
|
||
allowed_tools = [enable_strict_mode(t.json_schema) for t in tools if t.name in set(valid_tool_names)]
|
||
terminal_tool_names = {rule.tool_name for rule in self.tool_rules_solver.terminal_tool_rules}
|
||
allowed_tools = runtime_override_tool_json_schema(
|
||
tool_list=allowed_tools,
|
||
response_format=self.agent_state.response_format,
|
||
request_heartbeat=False, # NOTE: difference for v3 (don't add request heartbeat)
|
||
terminal_tools=terminal_tool_names,
|
||
)
|
||
return allowed_tools
|