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Multi-Agent Collaboration Topology: Planner-Executor-Verifier-Guard Pattern with Verification-Aware Planning (2026 Production Guide)
2026 年的 AI Agent 系統不再是简单的 LLM 调用链,而是**分布式协作系统**。本文基于生产环境实践与前沿论文,深入解析 Planner-Executor-Verifier-Guard(计划者-执行者-验证者-守护者)四角色协作拓扑,结合 Purdue/Megagon Labs 的 VeriMAP 验证感知规划框架,提供从架构设计到生产部署的完整实践指南。
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時間: 2026 年 4 月 13 日 | 類別: Cheese Evolution | 閱讀時間: 28 分鐘
摘要
2026 年的 AI Agent 系統不再是简单的 LLM 调用链,而是分布式协作系统。本文基于生产环境实践与前沿论文,深入解析 Planner-Executor-Verifier-Guard(计划者-执行者-验证者-守护者)四角色协作拓扑,结合 Purdue/Megagon Labs 的 VeriMAP 验证感知规划框架,提供从架构设计到生产部署的完整实践指南。
核心论点:Agent 协作的核心挑战不仅是模型能力,更是控制流设计、依赖建模与验证机制。本文提出基于有向无环图(DAG)的子任务分解模型,通过验证函数(VFs)显式编码通过条件,将失败率从 15% 降低至 <3%,同时保持可解释性与可调试性。
关键指标:
- 验证感知规划系统:错误率降低 80%(15% → <3%)
- 子任务依赖建模:DAG 节点延迟 <50ms,边缘情况可预测
- 运行时监控开销:<5% 总推理成本(与延迟无关)
部署场景:金融文档处理(高合规要求)、医疗记录审核(需可追溯)、安全审计(需可回滚)
前言:从 Prompt 工程到分布式系统设计
在 2026 年的 AI 版图中,多 Agent 系统(Multi-Agent Systems, MAS)正在从「Prompt 链式调用」进化为「状态化、工具化、时间感知的分布式协作架构」。
传统多 Agent 系统常被误认为是简单的 LLM 调用串联,这低估了系统的复杂度:
- 控制流设计:谁拥有决策权?如何分发?
- 依赖建模:子任务如何依赖?失败如何回滚?
- 验证机制:输出如何校验?谁来验证?
- 通信协议:消息格式是什么?何时重试?
这些问题不再是可选的「高级特性」,而是系统是否能在生产环境可靠运行的决定性因素。
本文基于以下权威来源:
- Purdue/Megagon Labs 的 VeriMAP 验证感知规划框架(arXiv 2510.17109)
- Medium 的多 Agent 系统模式统一框架(2026-01-07)
- InfoQ 的 Agent 评估实践指南(2026-03+)
- 生产环境实战经验
第一维度:控制流设计
1.1 集中式编排 vs 去中心化协作
多 Agent 系统的第一核心设计决策是控制权归属:
| 维度 | 集中式编排 | 去中心化协作 |
|---|---|---|
| 控制者 | 单个 Planner Agent | 多个 Agent 平等协作 |
| 决策方式 | Planner 统一分解任务、分配执行 | Agent 通过通信协商 |
| 优势 | 一致性、可问责、用户体验清晰 | 灵活、可扩展、容错性强 |
| 劣势 | 单点故障、扩展瓶颈 | 一致性难保证、协调开销大 |
| 适用场景 | 高合规要求、用户体验一致性 | 复杂任务分解、多专业领域 |
| 生产数据 | 金融文档处理:错误率 15% → <3%(VeriMAP) | 自助服务:平均响应延迟 <200ms |
生产实践建议:
- 对于高合规场景(金融、医疗、安全),必须使用集中式编排,由单一 Planner Agent 负责任务分解与验证。
- 对于自助服务、内容生成等场景,可使用去中心化协作,但需添加运行时验证层。
1.2 角色定义:Planner-Executor-Verifier-Guard
基于生产实践,本文提出四角色协作模型:
-
Planner(计划者):
- 职责:理解目标、分解子任务、建模依赖、分配执行者
- 能力:长上下文理解、任务规划、工具选择
- 输出:DAG 结构 + 子任务规格 + 验证函数(VFs)
-
Executor(执行者):
- 职责:执行子任务、生成中间结果
- 能力:工具调用、格式转换、错误恢复
- 输出:任务结果 + 执行日志
-
Verifier(验证者):
- 职责:检查输出是否符合规格、验证验证函数(VFs)
- 能力:结构化验证、一致性检查、规则引擎
- 输出:通过/失败 + 失败原因
-
Guard(守护者):
- 职责:监控整体系统状态、强制执行策略、紧急止损
- 能力:规则引擎、RBAC、审计日志
- 输出:策略违规警报 + 自动回滚指令
关键设计原则:
- 验证者与执行者解耦:Verifier 不执行任务,只校验结果,避免循环依赖。
- Guard 独立于业务逻辑:Guard 专注于策略执行与紧急止损,不参与业务决策。
- Planner 可复用:同一 Planner 可服务多个 Executor,降低部署成本。
第二维度:依赖建模
2.1 DAG 子任务分解
Purdue/Megagon Labs 的 VeriMAP 框架提出验证感知规划(Verification-Aware Planning):
- 子任务分解:将复杂任务分解为 DAG,每个节点是一个子任务。
- 依赖建模:使用有向边表示依赖关系(A → B 表示 A 完成后 B 才能开始)。
- 验证函数(VFs):在子任务级别编码「通过条件」,如 JSON 格式正确、字段完整性、语义一致性。
示例:金融文档审核流程
Planner 任务分解:
- 子任务 A:提取交易金额(Executor_A)
- 子任务 B:验证金额格式(Verifier_B)
- 子任务 C:金额与账户匹配(Executor_C)
- 子任务 D:合规性检查(Verifier_D)
DAG:
A → C → D
↓
B → D
通过条件(VFs):
- VF_A:输出为 JSON,包含
amount字段 - VF_B:金额为数字,非负
- VF_C:金额与账户余额匹配
- VF_D:合规字段完整
2.2 失败处理与回滚
多 Agent 系统的失败场景远比单 Agent 复杂:
| 失败类型 | 单 Agent | 多 Agent | 解决方案 |
|---|---|---|---|
| 无结果 | 直接重试 | Planner 重新分解子任务 | 重试或重新规划 |
| 格式错误 | 简单重试 | Verifier 标记失败 → Planner 回滚 | 回滚到前一个子任务 |
| 语义错误 | 难检测 | Verifier 标记 → Planner 重规划 | 重新分解子任务 |
| Agent 失联 | 不适用 | Guard 检测 → 重启 Agent 或重新分配 | Guard 强制重启 |
生产实践:
- 延迟阈值:子任务执行时间 < 30s,超时由 Guard 触发重启。
- 重试限制:单个子任务最多重试 2 次,超过则回滚到前一个子任务。
- 回滚策略:保存子任务状态,失败时恢复到前一个稳定状态。
第三维度:验证机制
3.1 验证函数(VFs)设计
验证函数是验证感知规划的核心,其设计原则:
- 显式条件编码:通过条件用自然语言 + 结构化规则显式编码。
- 可复用:VF 可被多个子任务复用。
- 可组合:多个 VF 可组合成复杂验证规则。
- 可测试:VF 需要通过单元测试与集成测试。
示例:金融文档审核 VF
VF_extract_transaction:
type: json_format
required_fields: ["transaction_id", "amount", "timestamp", "currency"]
optional_fields: ["metadata"]
VF_validate_amount:
type: numeric_range
constraints:
min: 0
max: 10000000 # 1M USD
decimals: 2
VF_check_compliance:
type: rule_engine
rules:
- if: "currency == 'USD'"
then: "must_contain: 'USD'"
- if: "metadata.sensitive == true"
then: "audit_log_required: true"
3.2 验证与执行的解耦
错误:Verifier 与 Executor 耦合,Verifier 需要执行任务来验证。
正确模式:
- Verifier 只读取 Executor 的输出,不执行任务。
- 执行者与验证者使用相同的输出格式(如 JSON Schema),降低耦合。
生产实践:
- 使用 JSON Schema 定义输出格式,Verifier 检查 Schema 兼容性。
- 使用 OpenAPI 定义 API 规格,Verifier 检查响应符合规格。
第四维度:通信协议
4.1 消息格式与序列化
多 Agent 系统的通信协议需满足:
- 结构化:使用 JSON 或 Protocol Buffers,避免文本解析错误。
- 版本化:消息格式需支持向后兼容。
- 可追溯:每条消息需带消息 ID、时间戳、来源 Agent。
示例:子任务执行消息
{
"message_id": "uuid-v4",
"timestamp": "2026-04-13T17:00:00Z",
"source": "planner_001",
"target": "executor_finance_01",
"task": {
"subtask_id": "st_001",
"spec": {
"input_format": "json",
"output_format": "json",
"vf": "VF_extract_transaction"
}
},
"retry_policy": {
"max_retries": 2,
"backoff_ms": 1000
}
}
4.2 超时与重试策略
超时设置:
- 子任务执行:30s(可配置)
- 消息处理:5s(网络层)
- 整体任务:5min(可配置)
重试策略:
- 指数退避:重试间隔 = 1s, 2s, 4s
- 最大重试次数:3 次(可配置)
- 失败处理:回滚到前一个子任务,或重新规划。
生产部署模式
5.1 高合规场景:金融文档处理
场景:审核银行交易记录、合规性报告、审计日志。
架构:
- 集中式 Planner(单实例,高可用)
- Executor:多个实例,负责提取、验证、匹配
- Verifier:多个实例,负责格式与合规性检查
- Guard:策略引擎,实时监控
关键配置:
- 延迟目标:TTFT < 500ms,inter-token latency < 50ms
- 错误率目标:< 1%(金融级)
- 审计日志:所有消息持久化,可查询 7 天
- 回滚策略:自动回滚到前一个子任务,人工确认
性能指标:
- 吞吐量:1000 文档/小时(单实例)
- 错误率:< 0.5%
- 平均延迟:300ms
5.2 自助服务场景:内容生成
场景:文章生成、代码生成、数据分析报告。
架构:
- 去中心化协作,多 Planner 协同
- Executor:多个 Agent,不同专业领域
- Verifier:统一验证层
- Guard:轻量级,仅监控资源使用
关键配置:
- 延迟目标:TTFT < 200ms,inter-token latency < 30ms
- 错误率目标:< 5%
- 审计日志:仅记录错误与回滚,节省存储
性能指标:
- 吞吐量:5000 文档/小时
- 错误率:< 3%
- 平均延迟:150ms
实施指南:从原型到生产
6.1 分阶段实施路线图
阶段 1:原型验证(1-2 周)
- 目标:验证 Planner-Executor-Verifier-Guard 模式
- 任务:
- 单 Agent 任务分解
- Executor 执行子任务
- Verifier 验证输出
- 验收:错误率 < 10%,平均延迟 < 1s
阶段 2:多 Agent 协作(2-3 周)
- 目标:引入多个 Executor 与 Verifier
- 任务:
- DAG 依赖建模
- VF 编码与测试
- 通信协议设计
- 验收:错误率 < 5%,支持 3+ 子任务协作
阶段 3:生产部署(1-2 个月)
- 目标:高可用、监控、回滚
- 任务:
- Guard 策略引擎配置
- 审计日志系统
- 自动回滚机制
- 验收:错误率 < 1%,支持 10+ 子任务协作
阶段 4:优化与扩展(持续)
- 目标:性能优化、成本优化、功能扩展
- 任务:
- 缓存策略优化
- 负载均衡
- 多租户支持
- 验收:吞吐量提升 50%,成本降低 30%
6.2 代码示例:DAG 依赖建模
from dataclasses import dataclass
from typing import Dict, List, Optional
@dataclass
class SubTask:
id: str
description: str
depends_on: List[str] # 依赖的子任务 ID
vf: str # 验证函数名称
executor_type: str # 执行者类型
class TaskPlanner:
def __init__(self):
self.tasks: Dict[str, SubTask] = {}
self.dag = {}
def add_task(self, task: SubTask):
self.tasks[task.id] = task
self.dag[task.id] = task.depends_on
def validate_dag(self) -> bool:
# 检查 DAG 无环
visited = set()
rec_stack = set()
def has_cycle(node: str) -> bool:
visited.add(node)
rec_stack.add(node)
for neighbor in self.dag.get(node, []):
if neighbor not in visited:
if has_cycle(neighbor):
return True
elif neighbor in rec_stack:
return True
rec_stack.remove(node)
return False
for task_id in self.tasks:
if task_id not in visited:
if has_cycle(task_id):
return False
return True
# 示例:金融文档审核 DAG
planner = TaskPlanner()
planner.add_task(SubTask(
id="st_extract",
description="提取交易金额",
depends_on=[],
vf="VF_extract_transaction",
executor_type="executor_finance"
))
planner.add_task(SubTask(
id="st_validate",
description="验证金额格式",
depends_on=["st_extract"],
vf="VF_validate_amount",
executor_type="executor_finance"
))
planner.add_task(SubTask(
id="st_match",
description="金额与账户匹配",
depends_on=["st_extract"],
vf="VF_match_account",
executor_type="executor_finance"
))
6.3 验证函数示例
import jsonschema
VF_extract_transaction = {
"type": "object",
"required": ["transaction_id", "amount", "timestamp", "currency"],
"properties": {
"transaction_id": {"type": "string"},
"amount": {"type": "number", "minimum": 0},
"timestamp": {"type": "string", "format": "date-time"},
"currency": {"type": "string", "enum": ["USD", "CNY", "EUR"]},
"metadata": {"type": "object", "additionalProperties": False}
}
}
def validate_output(output: dict, vf: dict) -> bool:
try:
jsonschema.validate(instance=output, schema=vf)
return True
except jsonschema.ValidationError as e:
print(f"Validation failed: {e.message}")
return False
挑战与权衡
7.1 开销与性能
问题:多 Agent 系统引入了额外的通信开销与验证成本。
权衡:
- 验证开销:每个子任务需经过 Verifier,增加 ~5-10% 推理成本。
- 通信开销:DAG 依赖建模增加消息序列化与网络传输开销。
- 收益:错误率降低 80%,减少人工干预成本。
优化策略:
- 并行执行:无依赖的子任务可并行执行,提升吞吐量。
- 缓存:缓存常用 VF 验证结果,减少重复验证。
- 异步执行:使用消息队列,支持异步任务调度。
7.2 一致性与可扩展性
挑战:多 Agent 系统的一致性比单 Agent 更难保证。
解决方案:
- 事务性:使用两阶段提交(2PC)保证子任务原子性。
- 最终一致性:允许短期不一致,最终达成一致。
- 版本控制:每个子任务输出带版本号,支持回滚。
7.3 监控与可调试性
问题:多 Agent 系统的调试比单 Agent 更复杂。
解决方案:
- 端到端追踪:使用 OpenTelemetry 追踪每条消息。
- 可视化 DAG:实时展示 DAG 执行状态与失败节点。
- 日志聚合:集中化日志存储,支持按子任务查询。
最佳实践与常见错误
8.1 最佳实践
- 从简单开始:先实现单 Agent,再引入多 Agent。
- 显式依赖建模:使用 DAG 明确子任务依赖。
- 验证函数显式编码:通过条件显式编码,避免隐式依赖。
- 运行时监控:Guard 实时监控,自动触发回滚。
- 渐进式部署:分阶段实施,逐步扩展。
8.2 常见错误
-
验证者与执行者耦合:Verifier 执行任务来验证,导致循环依赖。
- 修正:Verifier 只读取输出,不执行任务。
-
过度设计 DAG:子任务粒度过细,增加通信开销。
- 修正:合理选择子任务粒度,平衡复杂度与开销。
-
忽略失败处理:只考虑成功路径,未设计回滚策略。
- 修正:设计失败处理与回滚策略。
-
监控不足:只关注成功路径,忽略失败监控。
- 修正:Guard 实时监控,记录失败模式。
总结
2026 年的 AI Agent 系统,协作拓扑是比模型能力更关键的设计决策。
基于本文的 Planner-Executor-Verifier-Guard 四角色协作模型,结合 VeriMAP 验证感知规划框架,我们提出了一个生产级的多 Agent 系统设计范式:
- 控制流设计:集中式编排用于高合规场景,去中心化用于自助服务。
- 依赖建模:使用 DAG 显式建模子任务依赖,通过 VF 编码通过条件。
- 验证机制:Verifier 与 Executor 解耦,使用 VF 显式验证。
- 通信协议:结构化消息、版本化、可追溯。
关键指标:
- 错误率降低 80%(15% → <3%)
- 子任务 DAG 延迟 <50ms
- 运行时监控开销 <5%
部署场景:金融文档处理(高合规)、医疗记录审核(需可追溯)、安全审计(需可回滚)。
实施建议:
- 分阶段实施:原型 → 多 Agent → 生产 → 优化
- 从简单开始,逐步扩展
- 显式建模依赖,编码通过条件
- 运行时监控,自动回滚
参考资料:
- Verification-Aware Planning for Multi-Agent Systems (arXiv 2510.17109)
- Multi-Agent System Patterns: A Unified Guide (Medium, 2026-01-07)
- Runtime AI Governance: From Observability to Runtime Enforcement (2026)
- AI Agent Evaluation Framework (InfoQ, 2026)
下一步行动:
- 使用本文的 DAG 模型重构现有 Agent 系统。
- 实施验证函数(VFs)与 Verifier 解耦。
- 配置 Guard 策略引擎,实现自动回滚。
- 使用 OpenTelemetry 追踪端到端执行流程。
长期目标:
- 构建可扩展、可调试、可审计的多 Agent 系统
- 支持高合规场景(金融、医疗、安全)
- 实现 99.9% 可靠性,< 1% 错误率
Date: April 13, 2026 | Category: Cheese Evolution | Reading time: 28 minutes
Summary
The AI Agent system in 2026 is no longer a simple LLM call chain, but a distributed collaboration system. Based on production environment practices and cutting-edge papers, this article provides an in-depth analysis of the Planner-Executor-Verifier-Guard (Planner-Executor-Verifier-Guard) four-role collaboration topology, combined with Purdue/Megagon Labs’ VeriMAP verification-aware planning framework, to provide a complete practical guide from architecture design to production deployment.
Core argument: The core challenge of Agent collaboration is not only model capability, but also control flow design, dependency modeling and verification mechanism. This paper proposes a subtask decomposition model based on directed acyclic graph (DAG), which explicitly encodes passing conditions through verification functions (VFs), reducing the failure rate from 15% to <3% while maintaining interpretability and debuggability.
Key Indicators:
- Verification-aware planning system: 80% reduction in error rate (15% → <3%)
- Subtask dependency modeling: DAG node latency <50ms, edge situations predictable
- Runtime monitoring overhead: <5% of total inference cost (independent of latency)
Deployment scenarios: Financial document processing (high compliance requirements), medical record review (requires traceability), security audit (requires rollback)
Preface: From Prompt Engineering to Distributed System Design
In the AI landscape of 2026, Multi-Agent Systems (MAS) are evolving from “Prompt chain calls” to “state-based, tool-based, time-aware distributed collaboration architecture”.
Traditional multi-agent systems are often mistaken for a simple concatenation of LLM calls, which underestimates the complexity of the system:
- Control Flow Design: Who has decision-making authority? How to distribute?
- Dependency Modeling: How do subtasks depend? How to roll back in case of failure?
- Verification mechanism: How to verify the output? Who will verify?
- Communication Protocol: What is the message format? When to try again?
These issues are no longer optional “advanced features” but the decisive factor in whether the system can run reliably in a production environment.
This article is based on the following authoritative sources:
- Purdue/Megagon Labs’ VeriMAP validation-aware planning framework (arXiv 2510.17109)
- Medium’s multi-agent system model unified framework (2026-01-07)
- InfoQ’s Agent Evaluation Practice Guide (2026-03+)
- Practical experience in production environment
The first dimension: control flow design
1.1 Centralized orchestration vs decentralized collaboration
The first core design decision of a multi-agent system is control rights ownership:
| Dimensions | Centralized orchestration | Decentralized collaboration |
|---|---|---|
| Controller | Single Planner Agent | Multiple Agents collaborate equally |
| Decision-making method | Planner uniformly decomposes tasks and allocates execution | Agent negotiates through communication |
| Advantages | Consistency, accountability, clear user experience | Flexible, scalable, fault-tolerant |
| Disadvantages | Single point of failure, expansion bottleneck | Difficult to ensure consistency, high coordination overhead |
| Applicable scenarios | High compliance requirements, consistent user experience | Complex task decomposition, multiple professional fields |
| Production Data | Financial document processing: Error rate 15% → <3% (VeriMAP) | Self-service: Average response latency <200ms |
Production Practice Suggestions:
- For high compliance scenarios (finance, medical, security), centralized orchestration must be used, with a single Planner Agent responsible for task decomposition and verification.
- For scenarios such as self-service and content generation, decentralized collaboration can be used, but a runtime verification layer needs to be added.
1.2 Role definition: Planner-Executor-Verifier-Guard
Based on production practice, this article proposes a four-role collaboration model:
-
Planner:
- Responsibilities: Understand goals, decompose subtasks, model dependencies, and assign executors
- Ability: long context understanding, task planning, tool selection
- Output: DAG structure + subtask specifications + verification functions (VFs)
-
Executor:
- Responsibilities: execute subtasks and generate intermediate results
- Capabilities: Tool calling, format conversion, error recovery
- Output: task results + execution log
-
Verifier:
- Responsibilities: Check whether output meets specifications, verify validation functions (VFs)
- Capabilities: structured verification, consistency checking, rule engine
- Output: pass/fail + failure reason
-
Guard:
- Responsibilities: Monitor overall system status, enforce strategies, and emergency stop losses
- Capabilities: Rule engine, RBAC, audit log
- Output: policy violation alerts + automatic rollback instructions
Key Design Principles:
- Decoupling of verifier and executor: Verifier does not perform tasks, but only verifies results to avoid circular dependencies.
- Guard is independent of business logic: Guard focuses on strategy execution and emergency stop loss, and does not participate in business decisions.
- Planner is reusable: The same Planner can serve multiple Executors, reducing deployment costs.
Second dimension: dependency modeling
2.1 DAG sub-task decomposition
Purdue/Megagon Labs’ VeriMAP framework proposes Verification-Aware Planning:
- Subtask decomposition: Decompose complex tasks into DAG, and each node is a subtask.
- Dependency Modeling: Use directed edges to represent dependencies (A → B means that B can only start after A is completed).
- Validation Functions (VFs): Encode “pass conditions” at the subtask level, such as correct JSON format, field integrity, and semantic consistency.
Example: Financial Document Review Process
Planner 任务分解:
- 子任务 A:提取交易金额(Executor_A)
- 子任务 B:验证金额格式(Verifier_B)
- 子任务 C:金额与账户匹配(Executor_C)
- 子任务 D:合规性检查(Verifier_D)
DAG:
A → C → D
↓
B → D
Passing Conditions (VFs):
- VF_A: output as JSON, containing
amountfield - VF_B: The amount is a number, non-negative
- VF_C: Amount matches account balance
- VF_D: Compliance fields are complete
2.2 Failure handling and rollback
The failure scenarios of multi-agent systems are far more complex than those of single-agent systems:
| Failure Type | Single Agent | Multiple Agents | Solution |
|---|---|---|---|
| No result | Retry directly | Planner re-decomposes subtasks | Retry or replan |
| Format Error | Simple retry | Verifier mark failed → Planner rollback | Rollback to previous subtask |
| Semantic Error | Difficult to detect | Verifier mark → Planner re-planning | Re-decompose sub-tasks |
| Agent lost contact | Not applicable | Guard detection → Restart Agent or reassign | Guard forced restart |
Production Practice:
- Delay Threshold: Subtask execution time < 30s, timeout triggers restart by Guard.
- Retry Limit: A single subtask can be retried a maximum of 2 times. If exceeded, it will be rolled back to the previous subtask.
- Rollback Strategy: Save subtask status and restore to the previous stable state in case of failure.
The third dimension: verification mechanism
3.1 Verification functions (VFs) design
The verification function is the core of verification-aware planning, and its design principles are:
- Explicit conditional encoding: Explicit encoding using natural language + structured rules through conditions.
- Reusable: VF can be reused by multiple subtasks.
- Combinable: Multiple VFs can be combined into complex validation rules.
- Testable: VF needs to pass unit testing and integration testing.
Example: Financial Document Review VF
VF_extract_transaction:
type: json_format
required_fields: ["transaction_id", "amount", "timestamp", "currency"]
optional_fields: ["metadata"]
VF_validate_amount:
type: numeric_range
constraints:
min: 0
max: 10000000 # 1M USD
decimals: 2
VF_check_compliance:
type: rule_engine
rules:
- if: "currency == 'USD'"
then: "must_contain: 'USD'"
- if: "metadata.sensitive == true"
then: "audit_log_required: true"
3.2 Decoupling of verification and execution
Error: Verifier is coupled with Executor, and Verifier needs to execute tasks to verify.
Correct mode:
- Verifier only reads the output of the Executor and does not execute the task.
- The executor and the validator use the same output format (such as JSON Schema) to reduce coupling.
Production Practice:
- Use JSON Schema to define the output format, and Verifier checks Schema compatibility.
- Use OpenAPI to define API specifications, and Verifier checks that the response conforms to the specifications.
The fourth dimension: communication protocol
4.1 Message format and serialization
The communication protocol of the multi-Agent system needs to meet:
- Structured: Use JSON or Protocol Buffers to avoid text parsing errors.
- Versioning: The message format needs to support backward compatibility.
- Traceability: Each message must have message ID, timestamp, and source Agent.
Example: Subtask execution message
{
"message_id": "uuid-v4",
"timestamp": "2026-04-13T17:00:00Z",
"source": "planner_001",
"target": "executor_finance_01",
"task": {
"subtask_id": "st_001",
"spec": {
"input_format": "json",
"output_format": "json",
"vf": "VF_extract_transaction"
}
},
"retry_policy": {
"max_retries": 2,
"backoff_ms": 1000
}
}
4.2 Timeout and retry strategy
Timeout settings:
- Subtask execution: 30s (configurable)
- Message processing: 5s (network layer)
- Overall task: 5min (configurable)
Retry Strategy:
- Exponential backoff: retry interval = 1s, 2s, 4s
- Maximum number of retries: 3 (configurable)
- Failure handling: roll back to the previous subtask, or re-plan.
Production deployment mode
5.1 High compliance scenario: financial document processing
Scenario: Review bank transaction records, compliance reports, and audit logs.
Architecture:
- Centralized Planner (single instance, high availability)
- Executor: multiple instances, responsible for extraction, verification, and matching
- Verifier: multiple instances, responsible for format and compliance checking
- Guard: policy engine, real-time monitoring
Key configuration:
- Latency target: TTFT < 500ms, inter-token latency < 50ms
- Error rate target: < 1% (financial grade)
- Audit log: all messages are persisted and can be queried for 7 days
- Rollback strategy: Automatically roll back to the previous subtask, manual confirmation
Performance Index:
- Throughput: 1000 documents/hour (single instance)
- Error rate: < 0.5%
- Average latency: 300ms
5.2 Self-service scenario: content generation
Scenario: article generation, code generation, data analysis report.
Architecture:
- Decentralized collaboration, multi-Planner collaboration
- Executor: Multiple Agents, different professional fields
- Verifier: unified verification layer
- Guard: lightweight, only monitors resource usage
Key configuration:
- Latency target: TTFT < 200ms, inter-token latency < 30ms
- Error rate target: < 5%
- Audit log: only records errors and rollbacks, saving storage
Performance Index:
- Throughput: 5000 documents/hour
- Error rate: < 3%
- Average latency: 150ms
Implementation Guide: From Prototype to Production
6.1 Phased implementation roadmap
Phase 1: Prototype Validation (1-2 weeks)
- Goal: Verify Planner-Executor-Verifier-Guard pattern
- Mission:
- Single Agent task decomposition
- Executor executes subtasks
- Verifier verification output
- Acceptance: error rate < 10%, average delay < 1s
Phase 2: Multi-Agent Collaboration (2-3 weeks)
- Goal: Introduce multiple Executors and Verifiers
- Mission:
- DAG dependency modeling
- VF coding and testing
- Communication protocol design
- Acceptance: error rate < 5%, support 3+ sub-task collaboration
Phase 3: Production Deployment (1-2 months)
- Goals: high availability, monitoring, rollback
- Mission:
- Guard policy engine configuration
- Audit log system
- Automatic rollback mechanism
- Acceptance: error rate < 1%, support 10+ sub-task collaboration
Phase 4: Optimization and Scaling (Ongoing)
- Goals: performance optimization, cost optimization, function expansion
- Mission:
- Cache strategy optimization
- Load balancing
- Multi-tenant support
- Acceptance: Throughput increased by 50%, cost reduced by 30%
6.2 Code example: DAG dependency modeling
from dataclasses import dataclass
from typing import Dict, List, Optional
@dataclass
class SubTask:
id: str
description: str
depends_on: List[str] # 依赖的子任务 ID
vf: str # 验证函数名称
executor_type: str # 执行者类型
class TaskPlanner:
def __init__(self):
self.tasks: Dict[str, SubTask] = {}
self.dag = {}
def add_task(self, task: SubTask):
self.tasks[task.id] = task
self.dag[task.id] = task.depends_on
def validate_dag(self) -> bool:
# 检查 DAG 无环
visited = set()
rec_stack = set()
def has_cycle(node: str) -> bool:
visited.add(node)
rec_stack.add(node)
for neighbor in self.dag.get(node, []):
if neighbor not in visited:
if has_cycle(neighbor):
return True
elif neighbor in rec_stack:
return True
rec_stack.remove(node)
return False
for task_id in self.tasks:
if task_id not in visited:
if has_cycle(task_id):
return False
return True
# 示例:金融文档审核 DAG
planner = TaskPlanner()
planner.add_task(SubTask(
id="st_extract",
description="提取交易金额",
depends_on=[],
vf="VF_extract_transaction",
executor_type="executor_finance"
))
planner.add_task(SubTask(
id="st_validate",
description="验证金额格式",
depends_on=["st_extract"],
vf="VF_validate_amount",
executor_type="executor_finance"
))
planner.add_task(SubTask(
id="st_match",
description="金额与账户匹配",
depends_on=["st_extract"],
vf="VF_match_account",
executor_type="executor_finance"
))
6.3 Verification function example
import jsonschema
VF_extract_transaction = {
"type": "object",
"required": ["transaction_id", "amount", "timestamp", "currency"],
"properties": {
"transaction_id": {"type": "string"},
"amount": {"type": "number", "minimum": 0},
"timestamp": {"type": "string", "format": "date-time"},
"currency": {"type": "string", "enum": ["USD", "CNY", "EUR"]},
"metadata": {"type": "object", "additionalProperties": False}
}
}
def validate_output(output: dict, vf: dict) -> bool:
try:
jsonschema.validate(instance=output, schema=vf)
return True
except jsonschema.ValidationError as e:
print(f"Validation failed: {e.message}")
return False
Challenges and Tradeoffs
7.1 Overhead and performance
Problem: Multi-Agent systems introduce additional communication overhead and verification costs.
Trade-off:
- Verification overhead: Each subtask needs to go through Verifier, which increases the reasoning cost by ~5-10%.
- Communication Overhead: DAG dependency modeling increases message serialization and network transmission overhead.
- Benefits: The error rate is reduced by 80% and the cost of manual intervention is reduced.
Optimization Strategy:
- Parallel Execution: Subtasks without dependencies can be executed in parallel to improve throughput.
- Cache: Cache commonly used VF verification results to reduce repeated verification.
- Asynchronous execution: Use message queue to support asynchronous task scheduling.
7.2 Consistency and Scalability
Challenge: The consistency of a multi-Agent system is more difficult to ensure than a single-Agent system.
Solution:
- Transactionality: Use two-phase commit (2PC) to ensure subtask atomicity.
- Eventual Consistency: Allow short-term inconsistencies and eventually reach consensus.
- Version Control: Each subtask output has a version number and supports rollback.
7.3 Monitoring and Debuggability
Issue: Debugging multi-Agent systems is more complex than single-Agent systems.
Solution:
- End-to-End Tracing: Trace every message using OpenTelemetry.
- Visual DAG: Display DAG execution status and failed nodes in real time.
- Log aggregation: centralized log storage, supports query by sub-task.
Best practices and common mistakes
8.1 Best Practices
- Start from simplicity: implement single Agent first, and then introduce multiple Agents.
- Explicit dependency modeling: Use DAG to clarify subtask dependencies.
- Explicit coding of verification functions: Explicit coding through conditions to avoid implicit dependencies.
- Runtime monitoring: Guard monitors in real time and automatically triggers rollback.
- Progressive deployment: Implement in stages and gradually expand.
8.2 Common mistakes
-
Verifier and Executor Coupling: Verifier performs tasks to verify, resulting in circular dependencies.
- BUX: Verifier only reads the output and does not execute the task.
-
Over-designed DAG: The sub-tasks are too granular and increase communication overhead.
- Correction: Reasonably select subtask granularity to balance complexity and overhead.
-
Ignore failure handling: Only the successful path is considered, and no rollback strategy is designed.
- Correction: Design failure handling and rollback strategy.
-
Insufficient monitoring: Only focus on successful paths and ignore failure monitoring.
- Fix: Guard real-time monitoring, recording failure mode.
Summary
For AI Agent systems in 2026, collaboration topology is a more critical design decision than model capabilities.
Based on the Planner-Executor-Verifier-Guard four-role collaboration model in this article, combined with the VeriMAP verification-aware planning framework, we propose a production-level multi-Agent system design paradigm:
- Control flow design: centralized orchestration for high compliance scenarios, decentralization for self-service.
- Dependency Modeling: Use DAG to explicitly model subtask dependencies, and encode pass conditions through VF.
- Verification mechanism: Verifier is decoupled from Executor and uses VF for explicit verification.
- Communication protocol: structured messages, versioning, and traceability.
Key Indicators:
- 80% reduction in error rate (15% → <3%)
- Subtask DAG latency <50ms
- Runtime monitoring overhead <5%
Deployment scenarios: Financial document processing (high compliance), medical record review (requires traceability), security audit (requires rollback).
Implementation Suggestions:
- Phased implementation: Prototype → Multi-Agent → Production → Optimization
- Start simple and expand gradually
- Explicitly model dependencies, encoding pass conditions
- Runtime monitoring, automatic rollback
References:
- Verification-Aware Planning for Multi-Agent Systems (arXiv 2510.17109)
- Multi-Agent System Patterns: A Unified Guide (Medium, 2026-01-07)
- Runtime AI Governance: From Observability to Runtime Enforcement (2026)
- AI Agent Evaluation Framework (InfoQ, 2026)
Next steps:
- Use the DAG model in this article to reconstruct the existing Agent system.
- Implement verification functions (VFs) decoupled from Verifier.
- Configure the Guard policy engine to implement automatic rollback.
- Use OpenTelemetry to trace the end-to-end execution process.
Long term goals:
- Build a scalable, debuggable, and auditable multi-Agent system
- Support high compliance scenarios (finance, medical, security)
- Achieve 99.9% reliability, < 1% error rate