Dan Caldr 19266a5eac
fix(middlewares): end length-capped turns cleanly, prevent todo re-engagement, annotate write_file budget (#5569)
* fix(middlewares): end length-capped turns cleanly, prevent todo re-engagement, annotate write_file budget

When a model hits its per-response output cap (finish_reason=length) while
emitting a write_file tool call, ModelLengthFinishReasonMiddleware suppresses
the truncated call and stamps model_length_termination. TodoMiddleware must
not re-engage (jump_to=model) on such a capped turn -- doing so re-emits the
same oversized call into the same cap, producing up to 3 futile responses
with junk fragments instead of a clean truncation notice.

Changes:
- TodoMiddleware.after_model: skip completion reminder jump when
  additional_kwargs.model_length_termination is present (follows the existing
  deerflow_error_fallback precedent).
- ModelLengthFinishReasonMiddleware: always append the length notice when
  tool calls were suppressed, even when partial text survived (collapses the
  visible-content ternary). Fixes a latent bug in append_visible_text that
  silently dropped string content.
- tools.get_available_tools: annotate write_file's model-visible description
  with the model's configured max_tokens output budget. Guarded extraction
  safely handles missing or non-numeric tokens, and the tool is cloned via
  model_copy to keep module-level singletons immutable across assemblies and
  prevent guidance leakage to unbudgeted models.
- release_policy_parameters() updated for both middlewares.
- AGENTS.md chain entries (#20, #35) and module docstrings updated within
  AG002 guidance limits.
- Tests: 8 new/focused unit tests + 1 updated pin + 1 real create_agent()
  integration test reproducing the incident (thread b1723286).

* fix(tools): use effective model cap for write_file guidance

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
2026-09-20 19:28:21 +08:00

64 lines
2.3 KiB
Python

"""Shared model response content and termination classification."""
from __future__ import annotations
from typing import Any
from langchain_core.messages import AIMessage
def last_ai_message(response: Any) -> AIMessage | None:
"""Return the last assistant message from a middleware model result."""
if isinstance(response, AIMessage):
return response
result = getattr(response, "result", None)
if isinstance(result, (list, tuple)):
return next((message for message in reversed(result) if isinstance(message, AIMessage)), None)
return None
def has_tool_call_intent(message: AIMessage) -> bool:
"""Return whether parsed or provider-raw tool-call intent is present."""
if message.tool_calls or getattr(message, "invalid_tool_calls", None):
return True
additional_kwargs = message.additional_kwargs or {}
return bool(additional_kwargs.get("tool_calls") or additional_kwargs.get("function_call"))
def has_visible_content(message: AIMessage) -> bool:
"""Return whether a message contains non-whitespace user-visible text."""
content = message.content
if isinstance(content, str):
return bool(content.strip())
if not isinstance(content, list):
return False
for block in content:
if isinstance(block, str) and block.strip():
return True
if not isinstance(block, dict) or block.get("type") not in {"text", "output_text"}:
continue
text = block.get("text")
if isinstance(text, str) and text.strip():
return True
return False
def append_visible_text(message: AIMessage, text: str) -> Any:
"""Append a visible text block without dropping existing content blocks."""
if isinstance(message.content, list):
return [*message.content, {"type": "text", "text": text}]
if isinstance(message.content, str) and message.content.strip():
return f"{message.content}\n\n{text}"
return text
def finish_reason(message: AIMessage) -> str | None:
"""Read and normalize common provider termination-reason fields."""
for metadata in (message.response_metadata or {}, message.additional_kwargs or {}):
for field in ("finish_reason", "stop_reason"):
value = metadata.get(field)
if isinstance(value, str):
return value.strip().lower()
return None