Files
AgentLab/backend/tests/test_agent_steps.py
T
ThearchyHelios 4057cdc35f 步数用尽时先收个尾,别把半截过程当答案交出去
走到步数上限一定意味着最后那步**要求了工具**(不要工具的话循环早 break 了),
也就是说模型从来没拿到过"说结论"的那一轮——它只是被掐断在半路。交出去的
是它上一句中间过程的话,末尾补一句"步数不够,请调大"。

实测这条线是绷紧的:库里 116 个 agent 节点,87% 在 10 步内收口,11 步只有
1 个,**正好 12 步的有 11 个**。1 跳到 11 是被截断的特征,不是自然分布。

所以补上那一轮:不给工具,让它基于已经查到的收口,并说清哪些没查到、
结论因此有什么局限。用 base_model 而不是绑过工具的 model——收尾轮必须在
结构上发不出 tool_call,靠提示词请它别调是约束不住的。

两种收场发不同的 code:收上来了是 step_limit_settled(DEGRADED),
收不上来仍是 step_limit(BROKEN)。不复用同一个 code:库里那 8 条老事件
的含义确实是硬截断,改语义等于把历史运行重新解释成另一回事。

顺带修掉一个一直在白烧钱的 bug:chat.ts:440 的注释说自动重试能"调大最大
步数",而 copilot.py 明确禁止模型写 max_steps。两边对不上,于是 step_limit
的重试是用同一个默认 12 再跑一遍,必然撞同一堵墙。现在那条禁令改成有条件
的——只有上一次死于步数不够时才准显式写大值。改完两条路各自成立:收尾
成功走 DEGRADED,闸门不开、不重试(对的,同配置再跑还是撞墙);收尾失败
仍是 BROKEN,而这次 Copilot 真能把步数调大。

硬顶 25 → 100,画布滑块跟着放开,**节点默认仍是 12**:要更多的人调得动,
不知情的人不会突然多花十倍。

新增 tests/test_agent_steps.py,顺带补回 agent 循环的集成测试(原来那个
文件在脱敏那轮被整个删掉了)。两条反向断言是重点:正常收口的 agent 一次
调用都不该多花,以及收尾轮发不出工具调用。两者都做过变异验证——把收尾
结果丢弃、把收尾轮换成绑工具的 model,各自都能让对应的断言变红。

273 passed(去掉一个会真连 api.openai.com 的既有慢测试是 238 passed / 9.4s)。
2026-09-24 16:38:26 +08:00

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"""步数用尽时,agent 要收口,而不是把半截过程交出去。
走到步数上限一定意味着最后那步**要求了工具**(不要工具的话循环早 break 了),
也就是说模型从来没拿到过"说结论"的那一轮——它只是被掐断在半路。交出去的
是它上一句中间过程的话,末尾补一句"步数不够"。
所以补上那一轮:不给工具,让它基于已经查到的收口。这里守三件事——收尾轮
真的发生了、它**发不出**工具调用、以及它没有变成每次都多烧的一次调用。
顺带补回 agent 循环的集成测试:原来那个文件在脱敏那轮被整个删掉了。
"""
from __future__ import annotations
import asyncio
import pytest
from langchain_core.messages import AIMessage
from sqlalchemy import select
from app.db.base import SessionLocal
from app.db.models import Run, RunEvent
from app.engine.runner import run_manager
#: 收尾轮该说的话。挑一句和"中间过程"截然不同的,好分辨答案到底取自哪一轮
SETTLED = "已经查到的部分:门店 8 家。其余未查到,这个数是下限。"
MIDWAY = "中间过程:还得再查一张表。"
MAX_STEPS = 3
@pytest.fixture
async def runner():
await run_manager.setup()
yield run_manager
await run_manager.shutdown()
def _graph(*, max_steps: int = MAX_STEPS) -> dict:
return {
"nodes": [
{"id": "in", "type": "input", "data": {"config": {}}},
{"id": "work", "type": "agent", "data": {"config": {
"prompt": "{{ input.question }}",
"tools": ["calculator"],
"max_steps": max_steps,
"approval": "never",
}}},
{"id": "out", "type": "output", "data": {"config": {}}},
],
"edges": [{"source": "in", "target": "work"}, {"source": "work", "target": "out"}],
}
def never_concludes(monkeypatch, *, settle_raises: bool = False) -> None:
"""绑了工具就永远再要一次工具;没绑工具才说话。
`self.tools` 是 bind_tools 之后才有的。收尾轮走的是**没绑过工具**的
base_model,所以它必然落到下面那个分支——这正是"收尾轮发不出工具调用"
那条断言的着力点:真要是绑着工具过来的,拿到的就会是 MIDWAY。
"""
from app.providers import mock_model
def _decide(self, messages):
if self.tools:
return AIMessage(
content=MIDWAY,
tool_calls=[{"name": self.tools[0]["name"],
"args": {"expression": "1+1"},
"id": f"call_{len(messages)}"}],
)
if settle_raises:
raise RuntimeError("收尾轮炸了")
return AIMessage(content=SETTLED)
monkeypatch.setattr(mock_model.MockChatModel, "_decide", _decide)
async def _run(graph: dict, question: str = "有几家门店"):
run = await run_manager.start(graph=graph, input_payload={"question": question})
for _ in range(200):
await asyncio.sleep(0.05)
async with SessionLocal() as session:
row = (await session.execute(select(Run).where(Run.id == run.id))).scalar_one()
if row.status in ("succeeded", "failed", "cancelled"):
break
else:
pytest.fail("运行没有在 10 秒内结束")
async with SessionLocal() as session:
events = list((await session.execute(
select(RunEvent).where(RunEvent.run_id == run.id).order_by(RunEvent.seq)
)).scalars())
return events, row
def codes(events) -> list[str]:
return [e.data.get("code") for e in events
if e.type == "log" and (e.data or {}).get("level") == "warn"]
def answer_of(row) -> str:
from app.engine import review as rv
return rv.answer_text(row.output)
# --------------------------------------------------------------------------
@pytest.mark.asyncio
async def test_step_limit_ends_with_a_conclusion_not_a_stump(runner, monkeypatch) -> None:
"""这块改动的全部意义:交出去的是结论,不是中间过程加一句抱怨。"""
never_concludes(monkeypatch)
events, row = await _run(_graph())
assert row.status == "succeeded", row.error
text = answer_of(row)
assert SETTLED in text, text
assert MIDWAY not in text, f"上一句中间过程冒充了答案:{text}"
assert "step_limit_settled" in codes(events), codes(events)
@pytest.mark.asyncio
async def test_the_settle_round_has_no_tools_bound(runner, monkeypatch) -> None:
"""收尾轮必须在**结构上**发不出工具调用,而不是靠提示词请它别调。
mock 的判据就是"有没有绑工具":真要是把绑过工具的 model 传进了收尾轮,
它会照常再要一次工具,答案里出现的就是 MIDWAY。
"""
never_concludes(monkeypatch)
events, row = await _run(_graph())
assert SETTLED in answer_of(row)
# 工具调用次数正好等于步数——收尾轮一次都没多调
assert len([e for e in events if e.type == "tool.start"]) == MAX_STEPS
@pytest.mark.asyncio
async def test_the_settle_round_costs_exactly_one_extra_call(runner, monkeypatch) -> None:
"""多花的必须是可数的一次,不是一个说不清的尾巴。"""
never_concludes(monkeypatch)
events, _ = await _run(_graph())
assert len([e for e in events if e.type == "llm.start"]) == MAX_STEPS + 1
@pytest.mark.asyncio
async def test_a_normal_agent_does_not_pay_for_a_settle_round(runner, monkeypatch) -> None:
"""反向断言:正常收口的 agent 一分钱都不该多花。
没有这条,"每次都多跑一轮"这种退化会悄无声息地通过全部其他测试。
"""
from app.providers import mock_model
monkeypatch.setattr(mock_model.MockChatModel, "_decide",
lambda self, messages: AIMessage(content="直接就有结论了。"))
events, row = await _run(_graph())
assert "直接就有结论了。" in answer_of(row)
assert len([e for e in events if e.type == "llm.start"]) == 1
assert not [c for c in codes(events) if c and c.startswith("step_limit")]
@pytest.mark.asyncio
async def test_a_failed_settle_round_falls_back_and_keeps_what_was_found(
runner, monkeypatch
) -> None:
"""收尾轮自己挂了,不能把已经查到的一起赔进去。"""
never_concludes(monkeypatch, settle_raises=True)
events, row = await _run(_graph())
assert row.status == "succeeded", row.error
text = answer_of(row)
assert "settle_failed" in codes(events), codes(events)
# 退回原来的行为:老的 step_limit(BROKEN),而不是 settled 那个
assert "step_limit" in codes(events)
assert "step_limit_settled" not in codes(events)
# 已有成果还在,末尾挂着说明
assert MIDWAY in text and "用满了" in text, text
def test_max_steps_is_clamped_by_the_hard_cap() -> None:
"""节点上写多大都过不去硬顶——否则一张图就能把预算烧穿。"""
from app.core.config import settings
assert min(200, settings.max_agent_steps) == settings.max_agent_steps
assert settings.max_agent_steps >= 25, "抬高上限不该反而把原来能配的值挡回去"
# --------------------------------------------------------------------------
# 复核层怎么看这两种收场
# --------------------------------------------------------------------------
def _warn(message: str, code: str) -> dict:
return {"type": "log", "node_id": "work",
"data": {"level": "warn", "message": message, "code": code}}
OK_OUTPUT = {"text": SETTLED}
def test_a_settled_run_is_a_gap_not_a_break() -> None:
"""收口过的答案是完整一段话,只是覆盖面不全——那是缺口不是断裂。"""
from app.engine import review as rv
signals = rv.scan([_warn("用满了 3 步,基于已查到的部分给出", "step_limit_settled")],
OK_OUTPUT)
assert [s.severity for s in signals] == [rv.DEGRADED]
# 连带效果正是想要的:不再触发自动重跑
assert not rv.should_retry(signals)
def test_a_hard_truncation_is_still_broken_and_still_retries() -> None:
"""收尾轮没能收上来,判定一点没变——这条是防止改动把老路一起改坏。"""
from app.engine import review as rv
signals = rv.scan([_warn("用满了 3 步还没给出结论", "step_limit")], OK_OUTPUT)
assert rv.worst(signals) == rv.BROKEN
assert rv.should_retry(signals)