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P-t-E Architectural Pattern: Secure Plan-then-Execute Implementation Guide 2026
Production-grade architectural pattern separating strategic planning from tactical execution with LangGraph, CrewAI, and AutoGen code references, plus security implications and defense-in-depth strategies
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時間: 2026 年 4 月 13 日 | 類別: Cheese Evolution | 閱讀時間: 25 分鐘
導言:從 ReAct 到 P-t-E 的架構轉變
在 2026 年的 AI Agent 發展中,我們正經歷一場根本性的架構轉變:從被動的 ReAct(Reason + Act)模式轉向主動的 P-t-E(Plan-then-Execute)模式。
ReAct 的局限性:
- 計劃與執行混合在同一個 LLM 調用中
- 難以建立明確的控制流完整性
- 容易受到間接 Prompt Injection 攻擊
- 可預測性差,錯誤擴散快
P-t-E 的優勢:
- 控制流完整性:明確的 Planner → Executor 分離
- 安全性:間接 Prompt Injection 攻擊需要同時攻破兩個組件
- 可預測性:規劃階段與執行階段分離,錯誤範圍明確
- 成本效益:規劃使用高容量模型,執行使用專用模型
核心架構:P-t-E 三層模型
1. Planner 層:戰略規劃
職責:
- 理解整體目標
- 分析任務複雜度
- 拆解為可執行步驟
- 規劃執行順序
實作關鍵:
class PlannerAgent:
def plan(self, goal: str, context: Dict) -> List[Task]:
"""
生成可執行的任務列表
- 任務粒度:每個任務 < 100 tokens
- 任務依賴:DAG 拓撲排序
- 執行順序:優先處理依賴少的高優先級任務
"""
prompt = f"""
目標: {goal}
背景: {context}
規劃原則:
1. 每個任務 < 100 tokens,可由單個 LLM 完成
2. 任務之間的依賴關係明確
3. 高優先級任務(安全、驗證)優先
4. 低優先級任務(查詢、格式化)可延後
"""
return llm.generate(prompt)
安全性考量:
- Planner 只能產生「什麼做」的規劃,不能產生「怎麼做」的細節
- Planner 輸出需要 Verifier 檢查後才能交給 Executor
- Planner 不能訪問敏感工具(資料庫、API Key)
2. Executor 層:戰術執行
職責:
- 執行 Planner 規劃的任務
- 處理工具調用
- 收集結果
- 反饋給 Planner(如果需要重新規劃)
實作關鍵:
class ExecutorAgent:
def execute(self, task: Task) -> Result:
"""
執行單個任務
- 工具調用限制:最多 5 次重試
- 超時設置:每個工具調用 < 30 秒
- 錯誤處理:失敗 → 回報給 Planner
"""
if task.tool_call:
result = self.call_tool(task.tool_call)
if result.error:
raise ExecutionError(result.error)
return result
工具安全原則:
- 最小權限原則:每個 Agent 只能訪問必要的工具
- 作用域限制:工具調用結果只返回給 Planner,不直接暴露給用戶
- 沙箱執行:危險操作(代碼執行、網絡訪問)在隔離環境中運行
3. Verifier 層:驗證與回滾
職責:
- 在 Executor 完成後檢查結果
- 驗證結果符合規劃的預期
- 標記需要重新規劃的任務
實作關鍵:
class VerifierAgent:
def verify(self, task: Task, result: Result) -> bool:
"""
驗證結果是否符合預期
- 檢查:返回值格式是否正確
- 檢查:是否達到任務目標
- 檢查:是否有預期的副作用
"""
verification_prompt = f"""
任務: {task.description}
預期輸出格式: {task.expected_format}
實際輸出: {result.output}
問題:
- 是否符合預期的輸出格式?
- 是否達到任務目標?
- 是否有預期的副作用?
"""
return llm.generate(verification_prompt)
回滾策略:
- 任務失敗 → 標記為「需要重新規劃」
- 回報給 Planner → Planner 重新分析 → 生成新計劃
- 計劃失敗率 > 30% → 觸發人工介入
三大框架的 P-t-E 實作對比
LangGraph(圖狀工作流)
優點:
- 狀態管理:內建 TypedDict State 支援複雜狀態
- 可重新規劃:狀態圖支持動態重新規劃
- DAG 支持:自然表達任務依賴關係
缺點:
- 狀態定義複雜:需要在開始時明確定義所有狀態字段
- 調試困難:圖狀執行難以追蹤
- 學習曲線:需要理解 Graph、Node、Edge 的概念
P-t-E 實作:
from langgraph.graph import StateGraph, START, END
from typing import TypedDict
class AgentState(TypedDict):
goal: str
plan: List[Task]
current_task: Task
results: List[Result]
need_replan: bool
def planner(state: AgentState) -> AgentState:
plan = plan_agent.generate(state["goal"])
return {**state, "plan": plan, "need_replan": False}
def executor(state: AgentState) -> AgentState:
result = executor_agent.execute(state["current_task"])
return {**state, "results": state["results"] + [result]}
def verifier(state: AgentState) -> AgentState:
verified = verifier_agent.verify(state["current_task"], state["results"][-1])
if not verified:
return {**state, "need_replan": True}
return {**state, "need_replan": False}
builder = StateGraph(AgentState)
builder.add_node("planner", planner)
builder.add_node("executor", executor)
builder.add_node("verifier", verifier)
builder.add_edge(START, "planner")
builder.add_edge("planner", "executor")
builder.add_edge("executor", "verifier")
builder.add_conditional_edges("verifier",
lambda s: "replan" if s["need_replan"] else "end",
{"replan": "planner", "end": END})
graph = builder.compile()
CrewAI(角色化 Agent)
優點:
- 角色化設計:Agent 作為員工,職責明確
- 工具作用域聲明:支持聲明式工具訪問控制
- 日誌記錄:內建日誌支持
缺點:
- 日誌困難:調試時日誌不夠細緻
- 狀態管理:需要手動管理 Agent 間的協調
- 複雜系統難以優化:日誌問題導致優化困難
P-t-E 實作:
from crewai import Agent, Task, Crew
planner_agent = Agent(
role="Strategic Planner",
goal="Create a plan to achieve the user's goal",
tools=[],
verbose=False
)
executor_agent = Agent(
role="Task Executor",
goal="Execute tasks according to the plan",
tools=[search_tool, calculator_tool],
verbose=False
)
verifier_agent = Agent(
role="Result Verifier",
goal="Verify that the result meets expectations",
tools=[],
verbose=False
)
# Planner 任務
planner_task = Task(
description="Create a plan for {goal}",
expected_output="A list of tasks with dependencies",
agent=planner_agent
)
# Executor 任務
executor_task = Task(
description="Execute task {task}",
expected_output="Task result",
agent=executor_agent,
tools=[search_tool, calculator_tool]
)
# Verifier 任務
verifier_task = Task(
description="Verify that result meets expectations",
expected_output="Verification result (pass/fail)",
agent=verifier_agent
)
crew = Crew(
agents=[planner_agent, executor_agent, verifier_agent],
tasks=[planner_task, executor_task, verifier_task],
verbose=True
)
AutoGen(程序化協調)
優點:
- 程序化控制:明確的代碼控制協調流程
- 可擴展性:支持複雜的工作流
- 工具支持:內建強大的工具調用支持
缺點:
- 代碼可讀性:協調邏輯複雜時可讀性下降
- 初始化耗時:需要較長的設置時間
- 狀態管理:需要手動管理 Agent 間的消息傳遞
P-t-E 實作:
from autogen import AssistantAgent, UserProxyAgent
# Planner Agent
planner = AssistantAgent(
name="Planner",
system_message="You are a strategic planner. Create a plan for the user's goal.",
llm_config=planner_llm_config
)
# Executor Agent
executor = AssistantAgent(
name="Executor",
system_message="You are a task executor. Execute tasks according to the plan.",
llm_config=executor_llm_config,
human_input_mode="NEVER"
)
# Verifier Agent
verifier = AssistantAgent(
name="Verifier",
system_message="You are a result verifier. Verify that the result meets expectations.",
llm_config=verifier_llm_config
)
# User Agent (orchestrator)
user_proxy = UserProxyAgent(
name="User",
code_execution_config={"use_docker": True},
human_input_mode="TERMINATE"
)
# P-t-E 協調流程
def pte_workflow(user_proxy, planner, executor, verifier):
# 1. Planner 生成計劃
planner_message = planner.generate_message(f"Plan for: {user_goal}")
planner.send(planner_message)
# 2. Executor 執行
executor_message = executor.generate_message(f"Execute: {planner_output}")
executor.send(executor_message)
# 3. Verifier 驗證
verifier_message = verifier.generate_message(f"Verify: {executor_output}")
verifier.send(verifier_message)
# 4. 如果需要重新規劃,回報給 Planner
if need_replan:
planner.send(planner_message)
# 執行
user_proxy.initiate_chat(pte_workflow)
安全性與防禦深度策略
間接 Prompt Injection 攻擊防護
攻擊向量:
- Planner 接收包含惡意提示的用戶輸入
- Planner 將提示傳遞給 Executor
- Executor 執行惡意指令
防護措施:
1. 控制流完整性
def enforce_control_flow_integrity(state):
"""
確保 Planner 輸出只包含「什麼做」,不包含「怎麼做」
- Planner 輸出格式驗證:只允許 Task 列表
- Executor 輸入驗證:只允許 Task 對象
- Verifier 輸入驗證:只允許 Result 對象
"""
allowed_planner_output = r'^\d+\.\s+\{.*"action".*}$'
allowed_executor_input = r'^\{.*"action".*}$'
if not re.match(allowed_planner_output, planner_output):
raise SecurityError("Planner output contains executable instructions")
if not re.match(allowed_executor_input, executor_input):
raise SecurityError("Executor input contains planning instructions")
2. 權限最小化
class ToolRegistry:
def __init__(self):
self.tools = {
"search": {"level": "read", "scope": "public"},
"database": {"level": "write", "scope": "user_data"},
"execute_code": {"level": "admin", "scope": "sandbox"},
"api_call": {"level": "admin", "scope": "whitelisted"}
}
def check_permission(self, tool_name, agent_role):
"""
檢查 Agent 是否有權限訪問該工具
- Agent 角色決定權限等級
- 工具屬性決定作用域
"""
agent_level = self.get_agent_level(agent_role)
tool = self.tools[tool_name]
if agent_level > tool["level"]:
raise PermissionError(f"Agent {agent_role} lacks permission for {tool_name}")
if tool["scope"] not in self.get_agent_scope(agent_role):
raise ScopeError(f"Agent {agent_role} lacks scope for {tool_name}")
3. 任務作用域工具訪問
def scoped_tool_access(task: Task, agent: Agent):
"""
每個任務只能訪問特定工具
- 任務類型決定工具集
- Agent 角色決定可用工具
"""
allowed_tools = get_tools_for_task_type(task.type)
agent_tools = get_tools_for_agent_role(agent.role)
for tool_call in task.tools:
if tool_call not in allowed_tools or tool_call not in agent_tools:
raise ScopeError(f"Tool {tool_call} not allowed for task {task.id} and agent {agent.role}")
4. 沙箱代碼執行
class SandboxExecutor:
def execute_code(self, code: str) -> str:
"""
在沙箱環境中執行代碼
- 只允許 Python 標準庫
- 禁止網絡訪問
- 禁止文件系統訪問
- 超時限制:5 秒
"""
sandbox = RestrictedEnvironment(
allowed_modules=["os", "sys", "re", "json", "math"],
disallow_network=True,
disallow_filesystem=True,
timeout=5
)
try:
result = sandbox.execute(code)
return result
except TimeoutError:
raise ExecutionError("Code execution timeout")
except Exception as e:
raise ExecutionError(f"Code execution failed: {str(e)}")
防禦深度策略
1. Human-in-the-Loop(HITL)驗證
def human_in_the_loop_verification(state: AgentState):
"""
在關鍵決策點引入人工驗證
- 任務類型:安全、支付、刪除操作
- 驗證時機:Executor 完成後,結果返回前
"""
critical_tasks = ["payment", "delete", "deploy"]
if state.current_task.type in critical_tasks:
prompt = f"""
請確認是否執行以下操作:
任務: {state.current_task.description}
預期輸出: {state.current_task.expected_output}
實際輸出: {state.results[-1].output}
確認(是/否)?
"""
human_confirmation = input(prompt)
if human_confirmation.lower() != "是":
raise HumanInterventionRequired("Task requires human confirmation")
2. 動態重新規劃循環
def dynamic_replanning_loop(state: AgentState, max_iterations: int = 3):
"""
支援動態重新規劃
- 任務失敗 → 回報給 Planner
- Planner 重新分析 → 生成新計劃
- 最大迭代:3 次(防止無限循環)
"""
iteration = 0
while iteration < max_iterations and state.need_replan:
iteration += 1
# 回報給 Planner
planner.send(f"Task {state.current_task.id} failed. Please replan.")
# Planner 生成新計劃
new_plan = planner.generate(state.goal)
# 選擇下一個任務
state.current_task = select_next_task(new_plan, state.current_task)
# 執行
result = executor.execute(state.current_task)
# 驗證
verified = verifier.verify(state.current_task, result)
if not verified:
state.need_replan = True
else:
state.need_replan = False
if iteration >= max_iterations:
raise MaxIterationsExceeded(f"Max replanning iterations ({max_iterations}) reached")
3. DAG 並行執行
def parallel_execution_dag(dag: DAG) -> List[Result]:
"""
支持 DAG 的並行執行
- 無依賴的任務並行執行
- 依賴任務等待前置任務完成
- 資源限制:最多 4 個並行任務
"""
results = []
pending_tasks = dag.get_ready_tasks()
while pending_tasks or results:
# 並行執行無依賴任務
parallel_results = []
for task in pending_tasks[:4]: # 資源限制
result = executor.execute(task)
parallel_results.append((task, result))
# 任務完成,更新 DAG
dag.update(task.id, result)
# 收集結果
results.extend(parallel_results)
# 標記下一批無依賴任務
pending_tasks = dag.get_ready_tasks()
return results
實戰案例:客戶支持自動化 ROI 分析
案例背景
部署場景:
- 用戶量:100 萬 DAU
- 支持渠道:電話、電子郵件、即時聊天
- 當前人工支持:50 人/班次
P-t-E 架構部署:
# Planner Agent:規劃支持流程
planner = PlannerAgent(
tools=["knowledge_base", "faq_search"]
)
# Executor Agent:執行查詢
executor = ExecutorAgent(
tools=["knowledge_base", "faq_search", "escalation"]
)
# Verifier Agent:驗證答案
verifier = VerifierAgent(
tools=["quality_check"]
)
# P-t-E 工作流程
def customer_support_pipeline(user_query: str) -> str:
# 1. Planner 規劃
plan = planner.plan(user_query)
# 2. Executor 執行
result = executor.execute(plan)
# 3. Verifier 驗證
verified = verifier.verify(result)
# 4. 如果驗證失敗,重新規劃
if not verified:
plan = planner.replan(user_query)
result = executor.execute(plan)
verified = verifier.verify(result)
return result
ROI 分析
成本節省:
- 人工成本:50 人 × $15/小時 × 8 小時 × 365 天 = $2,190,000/年
- AI Agent 成本:$0.10/查詢 × 100 萬 DAU × 平均 5 次查詢/天 = $365,000/年
- 節省:$1,825,000/年
質量提升:
- 回答率:98%(從 85% 提升)
- CSAT:+40%(從 3.5/5 到 4.9/5)
- 平均響應時間:從 30 秒降低到 5 秒
失敗模式分析:
- 複雜問題:P-t-E 規劃失敗率 15%(需要人工介入)
- 政策更新:規劃依賴過時知識(需要定期更新 Planner)
- 新問題:未知問題無法規劃(需要 Escalation Agent)
風險與防護
1. 複雜問題處理
def handle_complex_query(query: str):
"""
複雜問題(需要人工介入)
- 長度 > 500 tokens
- 包含多個主題
- 語境複雜度 > 10
"""
if query_length(query) > 500:
if query_topics(query) > 3:
if context_complexity(query) > 10:
return escalate_to_human()
2. 政策更新機制
class KnowledgeUpdater:
def update_planner_knowledge(self, new_policy: str):
"""
更新 Planner 的知識庫
- 定期更新:每週
- 更新方式:人工審核 + Planner 學習
- 驗證:Verifier 確保新知識正確
"""
# 1. 人工審核新政策
human_review = self.human_review(new_policy)
if human_review.approved:
# 2. 更新 Planner 知識庫
self.planner.update_knowledge(new_policy)
# 3. 驗證新知識
test_query = "請解釋新政策內容"
result = self.verifier.verify(test_query, self.executor.execute(test_query))
if result.verified:
return True
else:
return self.rollback_update()
設計決策與權衡
權衡 1:P-t-E vs ReAct
P-t-E 優勢:
- 控制流完整性:明確的 Planner → Executor 分離
- 安全性:間接 Prompt Injection 攻擊需要同時攻破兩個組件
- 可預測性:錯誤範圍明確,易於調試
P-t-E 代價:
- 複雜度:需要管理三個組件
- 延遲:兩個組件之間的通訊開銷
- 學習曲線:需要理解三種角色的職責
ReAct 優勢:
- 簡單:單一 LLM 調用
- 延遲:無額外通訊開銷
ReAct 代價:
- 安全性:Prompt Injection 攻擊容易
- 可預測性:錯誤擴散快,難以追蹤
生產環境建議:
- P-t-E:優先選擇,特別是安全敏感、高可靠性場景
- ReAct:僅適合非敏感、低可靠性場景
權衡 2:LangGraph vs CrewAI vs AutoGen
選擇標準:
| 權衡因素 | LangGraph | CrewAI | AutoGen |
|---|---|---|---|
| 狀態管理 | ✅ 內建 TypedDict | ❌ 手動管理 | ⚠️ 需要手動管理 |
| 日誌支持 | ⚠️ 需要配置 | ❌ 調試困難 | ⚠️ 需要配置 |
| 工具作用域 | ✅ 聲明式 | ✅ 聲明式 | ✅ 內建 |
| 沙箱支持 | ⚠️ 需要配置 | ✅ 內建 | ✅ 內建 Docker |
| 學習曲線 | 中等 | 簡單 | 複雜 |
| 性能 | ✅ 高 | ⚠️ 中等 | ✅ 高 |
| 調試 | ⚠️ 困難 | ❌ 非常困難 | ⚠️ 可配置 |
生產環境建議:
- LangGraph:優先選擇,特別是複雜狀態、需要重新規劃的場景
- CrewAI:適合簡單場景、快速原型
- AutoGen:適合高可擴展性、需要程序化控制的場景
權衡 3:P-t-E vs 其他模式(如 Multi-Agent)
Multi-Agent 模式:
- 多個專用 Agent 協調完成任務
- 優點:專業化、可擴展性
- 缺點:複雜度高、通訊開銷大
P-t-E 模式:
- Planner → Executor → Verifier
- 優點:簡單、易於理解
- 缺點:單一 Planner 可能瓶頸
生產環境建議:
- P-t-E:優先選擇,特別是入門場景
- Multi-Agent:適合大型、複雜場景
關鍵度量指標
1. 規劃成功率(Planning Success Rate)
def calculate_planning_success_rate(state_history: List[AgentState]) -> float:
"""
規劃成功率 = (成功規劃次數) / (總規劃次數) × 100%
門檻:
- > 95%:優秀
- 80-95%:良好
- < 80%:需要改進
"""
successful_plans = sum(1 for state in state_history if state.planning_success)
total_plans = len(state_history)
return (successful_plans / total_plans) * 100
2. 執行成功率(Execution Success Rate)
def calculate_execution_success_rate(state_history: List[AgentState]) -> float:
"""
執行成功率 = (成功執行次數) / (總執行次數) × 100%
門檻:
- > 95%:優秀
- 80-95%:良好
- < 80%:需要改進
"""
successful_executions = sum(1 for state in state_history if state.execution_success)
total_executions = len(state_history)
return (successful_executions / total_executions) * 100
3. 人工介入率(Human Intervention Rate)
def calculate_human_intervention_rate(state_history: List[AgentState]) -> float:
"""
人工介入率 = (人工介入次數) / (總執行次數) × 100%
門檻:
- < 5%:優秀
- 5-15%:可接受
- > 15%:需要改進
"""
human_interventions = sum(1 for state in state_history if state.human_intervention)
total_executions = len(state_history)
return (human_interventions / total_executions) * 100
4. 平均響應時間(Average Response Time)
def calculate_average_response_time(state_history: List[AgentState]) -> float:
"""
平均響應時間 = (總響應時間) / (總請求次數)
門檻:
- < 5 秒:優秀(實時場景)
- 5-15 秒:良好
- > 15 秒:需要改進
"""
total_time = sum(state.response_time for state in state_history)
total_requests = len(state_history)
return total_time / total_requests
5. 成本效益比(Cost-Benefit Ratio)
def calculate_cost_benefit_ratio(state_history: List[AgentState]) -> float:
"""
成本效益比 = (節省的成本) / (AI Agent 運營成本)
門檻:
- > 5:優秀
- 2-5:良好
- < 2:需要改進
"""
human_cost = sum(state.human_cost for state in state_history)
ai_cost = sum(state.ai_cost for state in state_history)
return human_cost / ai_cost
部署場景
場景 1:客戶支持自動化
部署模式:
- P-t-E:Planner 規劃查詢流程,Executor 執行查詢,Verifier 驗證答案
- 框架:LangGraph(狀態管理)
- 工具:知識庫、FAQ、人工介入
部署邊界:
- 支持量:10 萬 - 100 萬 DAU
- 問題類型:查詢、FAQ、簡單諮詢
- 不適合:複雜諮詢、政策解釋
部署規模:
def deploy_customer_support(config: CustomerSupportConfig):
"""
客戶支持自動化部署配置
"""
config = {
"p_t_e": {
"planner": {
"model": "claude-3-opus-4.6",
"timeout": 30
},
"executor": {
"model": "claude-3-sonnet-4.6",
"tools": ["knowledge_base", "faq_search"]
},
"verifier": {
"model": "claude-3-haiku-1.5",
"threshold": 0.95
}
},
"human_intervention": {
"threshold": 0.15, # 15% 門檻
"escalation": {
"complex_query": {"length": 500, "topics": 3},
"policy_question": {"requires_confirmation": True}
}
},
"monitoring": {
"planning_success_rate": 0.95,
"execution_success_rate": 0.95,
"human_intervention_rate": 0.15,
"average_response_time": 5.0
}
}
return config
場景 2:金融交易 Agent
部署模式:
- P-t-E:Planner 規劃交易策略,Executor 執行交易,Verifier 驗證交易結果
- 框架:AutoGen(程序化控制)
- 工具:交易 API、風險評估、監管工具
部署邊界:
- 交易量:低到中等
- 風險等級:中等風險
- 監管要求:高
部署規模:
def deploy_finance_trading_agent(config: FinanceTradingConfig):
"""
金融交易 Agent 部署配置
"""
config = {
"p_t_e": {
"planner": {
"model": "claude-3-opus-4.6",
"timeout": 60,
"risk_level": "high"
},
"executor": {
"model": "claude-3-sonnet-4.6",
"tools": ["trading_api", "risk_assessment", "regulatory_tools"]
},
"verifier": {
"model": "claude-3-haiku-1.5",
"threshold": 0.99,
"human_confirmation": True
}
},
"human_intervention": {
"threshold": 0.05, # 5% 門檻(金融場景)
"confirmation_required": True # 所有交易需要確認
},
"monitoring": {
"planning_success_rate": 0.98,
"execution_success_rate": 0.99,
"human_intervention_rate": 0.05,
"average_response_time": 10.0,
"transaction_volume": "medium"
}
}
return config
場景 3:代碼生成 Agent
部署模式:
- P-t-E:Planner 規劃代碼生成任務,Executor 生成代碼,Verifier 檢查代碼
- 框架:LangGraph(狀態管理、重新規劃)
- 工具:代碼庫、測試框架、沙箱
部署邊界:
- 代碼量:中小型項目
- 技術棧:Python、JavaScript、Go
- 不適合:大型系統、嵌入式系統
部署規模:
def deploy_code_generation_agent(config: CodeGenerationConfig):
"""
代碼生成 Agent 部署配置
"""
config = {
"p_t_e": {
"planner": {
"model": "claude-3-opus-4.6",
"timeout": 120,
"code_scope": "medium"
},
"executor": {
"model": "claude-3-sonnet-4.6",
"tools": ["code_library", "test_framework", "sandbox"]
},
"verifier": {
"model": "claude-3-haiku-1.5",
"threshold": 0.90,
"code_quality_check": True
}
},
"human_intervention": {
"threshold": 0.10, # 10% 門檻
"code_review": True # 代碼需要審核
},
"monitoring": {
"planning_success_rate": 0.95,
"execution_success_rate": 0.90,
"human_intervention_rate": 0.10,
"average_response_time": 15.0,
"code_quality_score": 0.90
}
}
return config
總結:P-t-E 的生產級實作要點
核心要點
- 控制流完整性:Planner → Executor → Verifier 的明確分離
- 安全性:間接 Prompt Injection 攻擊的防護措施
- 權限管理:最小權限原則、任務作用域工具訪問
- 防禦深度:Human-in-the-Loop、動態重新規劃、沙箱執行
- 框架選擇:LangGraph(複雜狀態)、CrewAI(簡單場景)、AutoGen(高可擴展)
實作檢查清單
部署前檢查:
- [ ] Planner 能否正確拆解任務?
- [ ] Executor 工具訪問權限是否正確?
- [ ] Verifier 能否正確驗證結果?
- [ ] 人工介入門檻是否合理?
- [ ] 監控指標是否配置?
測試檢查:
- [ ] 規劃成功率 > 95%?
- [ ] 執行成功率 > 95%?
- [ ] 人工介入率 < 15%?
- [ ] 平均響應時間 < 15 秒?
- [ ] 成本效益比 > 2?
生產檢查:
- [ ] 錯誤處理是否完善?
- [ ] 日誌記錄是否完整?
- [ ] 監控告警是否配置?
- [ ] 回滾策略是否測試?
- [ ] 人工介入流程是否測試?
下一步行動
立即行動:
- 選擇框架:LangGraph(複雜狀態)、CrewAI(簡單場景)、AutoGen(高可擴展性)
- 部署 P-t-E 架構:Planner → Executor → Verifier
- 實施安全性:控制流完整性、權限管理、沙箱執行
- 配置監控:規劃成功率、執行成功率、人工介入率
短期行動(1-2 週):
- 部署客戶支持自動化(P-t-E + LangGraph)
- 監控指標:規劃成功率、執行成功率、人工介入率
- 優化:人工介入門檻、響應時間、成本效益比
中期行動(1-2 個月):
- 擴展:金融交易 Agent、代碼生成 Agent
- 優化:動態重新規劃、Human-in-the-Loop
- 安全性:Policy 更新機制、Escalation Agent
長期行動(3-6 個月):
- 擴展:多 Agent 協調、Multi-Agent + P-t-E
- 優化:自動化監控、自動化優化
- 安全性:自動化 Policy 更新、自動化 Escalation
參考來源:
- arXiv:2509.08646 - Architecting Resilient LLM Agents: A Guide to Secure Plan-then-Execute Implementations
- Medium - First hand comparison of LangGraph, CrewAI and AutoGen
- Sprinklr Blog - How to Improve Customer Service ROI with AI
- GetMaxim AI - The Ultimate Checklist for Rapidly Deploying AI Agents in Production
- Galileo AI - Production Readiness Checklist for Every AI Agent
關鍵度量:
- 規劃成功率 > 95%:優秀
- 執行成功率 > 95%:優秀
- 人工介入率 < 15%:可接受
- 平均響應時間 < 15 秒:良好
- 成本效益比 > 2:良好
推薦閱讀:
- LangGraph 官方文檔:https://langchain-ai.github.io/langgraph/
- CrewAI 官方文檔:https://docs.crewai.com/
- AutoGen 官方文檔:https://microsoft.github.io/autogen/
Date: April 13, 2026 | Category: Cheese Evolution | Reading time: 25 minutes
Introduction: Architectural transformation from ReAct to P-t-E
In the development of AI Agent in 2026, we are experiencing a fundamental architectural shift: from the passive ReAct (Reason + Act) mode to the active P-t-E (Plan-then-Execute) mode.
Limitations of ReAct:
- Planning and execution are mixed in the same LLM call
- Difficulty establishing clear control flow integrity
- Vulnerable to indirect prompt injection attacks
- Poor predictability and fast error propagation
P-t-E Advantages:
- Control Flow Integrity: Explicit Planner → Executor separation
- Security: Indirect Prompt Injection attack requires compromising two components at the same time
- Predictability: separation of planning and execution phases, clear scope for errors
- Cost Effectiveness: Use high-volume models for planning, use dedicated models for execution
Core architecture: P-t-E three-layer model
1. Planner layer: strategic planning
Responsibilities:
- Understand the overall goals -Analyze task complexity
- broken down into executable steps
- Plan execution sequence
Implementation Key:
class PlannerAgent:
def plan(self, goal: str, context: Dict) -> List[Task]:
"""
生成可執行的任務列表
- 任務粒度:每個任務 < 100 tokens
- 任務依賴:DAG 拓撲排序
- 執行順序:優先處理依賴少的高優先級任務
"""
prompt = f"""
目標: {goal}
背景: {context}
規劃原則:
1. 每個任務 < 100 tokens,可由單個 LLM 完成
2. 任務之間的依賴關係明確
3. 高優先級任務(安全、驗證)優先
4. 低優先級任務(查詢、格式化)可延後
"""
return llm.generate(prompt)
Security Considerations:
- Planner can only generate “what to do” plans, but cannot generate “how to do” details
- Planner output needs to be checked by Verifier before it can be handed over to Executor
- Planner cannot access sensitive tools (database, API Key)
2. Executor layer: tactical execution
Responsibilities:
- Execute tasks planned by Planner
- Handle tool calls
- Collect results
- Feedback to Planner (if re-planning is needed)
Implementation Key:
class ExecutorAgent:
def execute(self, task: Task) -> Result:
"""
執行單個任務
- 工具調用限制:最多 5 次重試
- 超時設置:每個工具調用 < 30 秒
- 錯誤處理:失敗 → 回報給 Planner
"""
if task.tool_call:
result = self.call_tool(task.tool_call)
if result.error:
raise ExecutionError(result.error)
return result
Tool Safety Principles:
- Principle of Least Privilege: Each Agent can only access necessary tools
- Scope restriction: Tool call results are only returned to Planner and are not directly exposed to users
- Sandbox Execution: Dangerous operations (code execution, network access) are run in an isolated environment
3. Verifier layer: verification and rollback
Responsibilities:
- Check the results after the Executor completes
- Verification results meet planning expectations
- Mark tasks that need to be rescheduled
Implementation Key:
class VerifierAgent:
def verify(self, task: Task, result: Result) -> bool:
"""
驗證結果是否符合預期
- 檢查:返回值格式是否正確
- 檢查:是否達到任務目標
- 檢查:是否有預期的副作用
"""
verification_prompt = f"""
任務: {task.description}
預期輸出格式: {task.expected_format}
實際輸出: {result.output}
問題:
- 是否符合預期的輸出格式?
- 是否達到任務目標?
- 是否有預期的副作用?
"""
return llm.generate(verification_prompt)
Rollback Strategy:
- Mission failed → marked as “needs replanning”
- Report to Planner → Planner reanalyzes → Generate new plan
- Plan failure rate > 30% → trigger manual intervention
Comparison of P-t-E implementation of three major frameworks
LangGraph (graph workflow)
Advantages:
- State Management: Built-in TypedDict State supports complex states
- Re-planning: The state diagram supports dynamic re-planning
- DAG support: natural expression of task dependencies
Disadvantages:
- Complex state definition: all state fields need to be defined explicitly at the beginning
- Debugging Difficulties: Graphical execution is difficult to trace
- Learning Curve: Need to understand the concepts of Graph, Node, and Edge
P-t-E implementation:
from langgraph.graph import StateGraph, START, END
from typing import TypedDict
class AgentState(TypedDict):
goal: str
plan: List[Task]
current_task: Task
results: List[Result]
need_replan: bool
def planner(state: AgentState) -> AgentState:
plan = plan_agent.generate(state["goal"])
return {**state, "plan": plan, "need_replan": False}
def executor(state: AgentState) -> AgentState:
result = executor_agent.execute(state["current_task"])
return {**state, "results": state["results"] + [result]}
def verifier(state: AgentState) -> AgentState:
verified = verifier_agent.verify(state["current_task"], state["results"][-1])
if not verified:
return {**state, "need_replan": True}
return {**state, "need_replan": False}
builder = StateGraph(AgentState)
builder.add_node("planner", planner)
builder.add_node("executor", executor)
builder.add_node("verifier", verifier)
builder.add_edge(START, "planner")
builder.add_edge("planner", "executor")
builder.add_edge("executor", "verifier")
builder.add_conditional_edges("verifier",
lambda s: "replan" if s["need_replan"] else "end",
{"replan": "planner", "end": END})
graph = builder.compile()
CrewAI (role-based Agent)
Advantages:
- Role-based design: Agent is an employee with clear responsibilities
- Tool scope declaration: supports declarative tool access control
- Logging: built-in logging support
Disadvantages:
- Difficulty in logging: The logs are not detailed enough during debugging.
- Status Management: Requires manual management of coordination between Agents
- Complex systems are difficult to optimize: Log problems make optimization difficult
P-t-E implementation:
from crewai import Agent, Task, Crew
planner_agent = Agent(
role="Strategic Planner",
goal="Create a plan to achieve the user's goal",
tools=[],
verbose=False
)
executor_agent = Agent(
role="Task Executor",
goal="Execute tasks according to the plan",
tools=[search_tool, calculator_tool],
verbose=False
)
verifier_agent = Agent(
role="Result Verifier",
goal="Verify that the result meets expectations",
tools=[],
verbose=False
)
# Planner 任務
planner_task = Task(
description="Create a plan for {goal}",
expected_output="A list of tasks with dependencies",
agent=planner_agent
)
# Executor 任務
executor_task = Task(
description="Execute task {task}",
expected_output="Task result",
agent=executor_agent,
tools=[search_tool, calculator_tool]
)
# Verifier 任務
verifier_task = Task(
description="Verify that result meets expectations",
expected_output="Verification result (pass/fail)",
agent=verifier_agent
)
crew = Crew(
agents=[planner_agent, executor_agent, verifier_agent],
tasks=[planner_task, executor_task, verifier_task],
verbose=True
)
AutoGen (Programmatic Coordination)
Advantages:
- Procedural Control: clear code control and coordination process
- Scalability: Support complex workflows
- Tool Support: Built-in powerful tool calling support
Disadvantages:
- Code readability: readability decreases when coordination logic is complex
- Initialization time: requires a long setup time
- State Management: Requires manual management of messaging between Agents
P-t-E implementation:
from autogen import AssistantAgent, UserProxyAgent
# Planner Agent
planner = AssistantAgent(
name="Planner",
system_message="You are a strategic planner. Create a plan for the user's goal.",
llm_config=planner_llm_config
)
# Executor Agent
executor = AssistantAgent(
name="Executor",
system_message="You are a task executor. Execute tasks according to the plan.",
llm_config=executor_llm_config,
human_input_mode="NEVER"
)
# Verifier Agent
verifier = AssistantAgent(
name="Verifier",
system_message="You are a result verifier. Verify that the result meets expectations.",
llm_config=verifier_llm_config
)
# User Agent (orchestrator)
user_proxy = UserProxyAgent(
name="User",
code_execution_config={"use_docker": True},
human_input_mode="TERMINATE"
)
# P-t-E 協調流程
def pte_workflow(user_proxy, planner, executor, verifier):
# 1. Planner 生成計劃
planner_message = planner.generate_message(f"Plan for: {user_goal}")
planner.send(planner_message)
# 2. Executor 執行
executor_message = executor.generate_message(f"Execute: {planner_output}")
executor.send(executor_message)
# 3. Verifier 驗證
verifier_message = verifier.generate_message(f"Verify: {executor_output}")
verifier.send(verifier_message)
# 4. 如果需要重新規劃,回報給 Planner
if need_replan:
planner.send(planner_message)
# 執行
user_proxy.initiate_chat(pte_workflow)
Security and Defense in Depth Strategy
Indirect Prompt Injection attack protection
Attack Vector:
- Planner receives user input containing malicious prompts
- Planner passes the prompt to Executor
- Executor executes malicious instructions
Protective Measures:
1. Control flow integrity
def enforce_control_flow_integrity(state):
"""
確保 Planner 輸出只包含「什麼做」,不包含「怎麼做」
- Planner 輸出格式驗證:只允許 Task 列表
- Executor 輸入驗證:只允許 Task 對象
- Verifier 輸入驗證:只允許 Result 對象
"""
allowed_planner_output = r'^\d+\.\s+\{.*"action".*}$'
allowed_executor_input = r'^\{.*"action".*}$'
if not re.match(allowed_planner_output, planner_output):
raise SecurityError("Planner output contains executable instructions")
if not re.match(allowed_executor_input, executor_input):
raise SecurityError("Executor input contains planning instructions")
2. Minimize permissions
class ToolRegistry:
def __init__(self):
self.tools = {
"search": {"level": "read", "scope": "public"},
"database": {"level": "write", "scope": "user_data"},
"execute_code": {"level": "admin", "scope": "sandbox"},
"api_call": {"level": "admin", "scope": "whitelisted"}
}
def check_permission(self, tool_name, agent_role):
"""
檢查 Agent 是否有權限訪問該工具
- Agent 角色決定權限等級
- 工具屬性決定作用域
"""
agent_level = self.get_agent_level(agent_role)
tool = self.tools[tool_name]
if agent_level > tool["level"]:
raise PermissionError(f"Agent {agent_role} lacks permission for {tool_name}")
if tool["scope"] not in self.get_agent_scope(agent_role):
raise ScopeError(f"Agent {agent_role} lacks scope for {tool_name}")
3. Task scope tool access
def scoped_tool_access(task: Task, agent: Agent):
"""
每個任務只能訪問特定工具
- 任務類型決定工具集
- Agent 角色決定可用工具
"""
allowed_tools = get_tools_for_task_type(task.type)
agent_tools = get_tools_for_agent_role(agent.role)
for tool_call in task.tools:
if tool_call not in allowed_tools or tool_call not in agent_tools:
raise ScopeError(f"Tool {tool_call} not allowed for task {task.id} and agent {agent.role}")
4. Sandbox code execution
class SandboxExecutor:
def execute_code(self, code: str) -> str:
"""
在沙箱環境中執行代碼
- 只允許 Python 標準庫
- 禁止網絡訪問
- 禁止文件系統訪問
- 超時限制:5 秒
"""
sandbox = RestrictedEnvironment(
allowed_modules=["os", "sys", "re", "json", "math"],
disallow_network=True,
disallow_filesystem=True,
timeout=5
)
try:
result = sandbox.execute(code)
return result
except TimeoutError:
raise ExecutionError("Code execution timeout")
except Exception as e:
raise ExecutionError(f"Code execution failed: {str(e)}")
Defense in Depth Strategy
1. Human-in-the-Loop (HITL) Verification
def human_in_the_loop_verification(state: AgentState):
"""
在關鍵決策點引入人工驗證
- 任務類型:安全、支付、刪除操作
- 驗證時機:Executor 完成後,結果返回前
"""
critical_tasks = ["payment", "delete", "deploy"]
if state.current_task.type in critical_tasks:
prompt = f"""
請確認是否執行以下操作:
任務: {state.current_task.description}
預期輸出: {state.current_task.expected_output}
實際輸出: {state.results[-1].output}
確認(是/否)?
"""
human_confirmation = input(prompt)
if human_confirmation.lower() != "是":
raise HumanInterventionRequired("Task requires human confirmation")
2. Dynamic re-planning loop
def dynamic_replanning_loop(state: AgentState, max_iterations: int = 3):
"""
支援動態重新規劃
- 任務失敗 → 回報給 Planner
- Planner 重新分析 → 生成新計劃
- 最大迭代:3 次(防止無限循環)
"""
iteration = 0
while iteration < max_iterations and state.need_replan:
iteration += 1
# 回報給 Planner
planner.send(f"Task {state.current_task.id} failed. Please replan.")
# Planner 生成新計劃
new_plan = planner.generate(state.goal)
# 選擇下一個任務
state.current_task = select_next_task(new_plan, state.current_task)
# 執行
result = executor.execute(state.current_task)
# 驗證
verified = verifier.verify(state.current_task, result)
if not verified:
state.need_replan = True
else:
state.need_replan = False
if iteration >= max_iterations:
raise MaxIterationsExceeded(f"Max replanning iterations ({max_iterations}) reached")
3. DAG parallel execution
def parallel_execution_dag(dag: DAG) -> List[Result]:
"""
支持 DAG 的並行執行
- 無依賴的任務並行執行
- 依賴任務等待前置任務完成
- 資源限制:最多 4 個並行任務
"""
results = []
pending_tasks = dag.get_ready_tasks()
while pending_tasks or results:
# 並行執行無依賴任務
parallel_results = []
for task in pending_tasks[:4]: # 資源限制
result = executor.execute(task)
parallel_results.append((task, result))
# 任務完成,更新 DAG
dag.update(task.id, result)
# 收集結果
results.extend(parallel_results)
# 標記下一批無依賴任務
pending_tasks = dag.get_ready_tasks()
return results
Practical Case: Customer Support Automation ROI Analysis
Case background
Deployment Scenario:
- Number of users: 1 million DAU
- Support channels: phone, email, live chat
- Current human support: 50 people/shift
P-t-E architecture deployment:
# Planner Agent:規劃支持流程
planner = PlannerAgent(
tools=["knowledge_base", "faq_search"]
)
# Executor Agent:執行查詢
executor = ExecutorAgent(
tools=["knowledge_base", "faq_search", "escalation"]
)
# Verifier Agent:驗證答案
verifier = VerifierAgent(
tools=["quality_check"]
)
# P-t-E 工作流程
def customer_support_pipeline(user_query: str) -> str:
# 1. Planner 規劃
plan = planner.plan(user_query)
# 2. Executor 執行
result = executor.execute(plan)
# 3. Verifier 驗證
verified = verifier.verify(result)
# 4. 如果驗證失敗,重新規劃
if not verified:
plan = planner.replan(user_query)
result = executor.execute(plan)
verified = verifier.verify(result)
return result
ROI Analysis
Cost Savings:
- Labor costs: 50 people × $15/hour × 8 hours × 365 days = $2,190,000/year
- AI Agent Cost: $0.10/query × 1 million DAU × average 5 queries/day = $365,000/year
- Savings: $1,825,000/year
Quality Improvement:
- Response Rate: 98% (up from 85%)
- CSAT: +40% (from 3.5/5 to 4.9/5)
- Average response time: reduced from 30 seconds to 5 seconds
Failure Mode Analysis:
- Complex problem: P-t-E planning failure rate 15% (requires manual intervention)
- Policy Update: Planning relies on outdated knowledge (needs regular updates to Planner)
- New problem: Unknown problem cannot be planned (requires Escalation Agent)
Risk and Protection
1. Complex problem handling
def handle_complex_query(query: str):
"""
複雜問題(需要人工介入)
- 長度 > 500 tokens
- 包含多個主題
- 語境複雜度 > 10
"""
if query_length(query) > 500:
if query_topics(query) > 3:
if context_complexity(query) > 10:
return escalate_to_human()
2. Policy update mechanism
class KnowledgeUpdater:
def update_planner_knowledge(self, new_policy: str):
"""
更新 Planner 的知識庫
- 定期更新:每週
- 更新方式:人工審核 + Planner 學習
- 驗證:Verifier 確保新知識正確
"""
# 1. 人工審核新政策
human_review = self.human_review(new_policy)
if human_review.approved:
# 2. 更新 Planner 知識庫
self.planner.update_knowledge(new_policy)
# 3. 驗證新知識
test_query = "請解釋新政策內容"
result = self.verifier.verify(test_query, self.executor.execute(test_query))
if result.verified:
return True
else:
return self.rollback_update()
Design Decisions and Tradeoffs
Trade-off 1: P-t-E vs ReAct
P-t-E Advantages:
- Control flow integrity: clear Planner → Executor separation
- Security: Indirect Prompt Injection attack requires breaking two components at the same time
- Predictability: clear error scope and easy debugging
P-t-E Cost:
- Complexity: three components need to be managed
- Latency: communication overhead between two components
- Learning curve: need to understand the responsibilities of the three roles
ReAct Advantages:
- Simple: single LLM call
- Latency: no additional communication overhead
ReAct Price:
- Security: Prompt Injection attacks are easy
- Predictability: errors spread quickly and are difficult to track
Production Environment Recommendations:
- P-t-E: Priority selection, especially in security-sensitive and high-reliability scenarios
- ReAct: only suitable for non-sensitive, low reliability scenarios
Trade-off 2: LangGraph vs CrewAI vs AutoGen
Selection Criteria:
| Trade-offs | LangGraph | CrewAI | AutoGen |
|---|---|---|---|
| Status Management | ✅ Built-in TypedDict | ❌ Manual management | ⚠️ Manual management required |
| Log support | ⚠️ Requires configuration | ❌ Difficulty in debugging | ⚠️ Requires configuration |
| Tool Scope | ✅ Declarative | ✅ Declarative | ✅ Built-in |
| Sandbox Support | ⚠️ Configuration required | ✅ Built-in | ✅ Built-in Docker |
| Learning Curve | Medium | Simple | Complex |
| PERFORMANCE | ✅ HIGH | ⚠️ MEDIUM | ✅ HIGH |
| DEBUG | ⚠️ Hard | ❌ Very Hard | ⚠️ Configurable |
Production Environment Recommendations:
- LangGraph: Priority selection, especially for complex states and scenarios that require re-planning
- CrewAI: suitable for simple scenarios and rapid prototyping
- AutoGen: suitable for scenarios with high scalability and requiring programmatic control
Trade-off 3: P-t-E vs other modes (such as Multi-Agent)
Multi-Agent Mode:
- Multiple dedicated Agents coordinate to complete tasks
- Advantages: specialization, scalability
- Disadvantages: high complexity, large communication overhead
P-t-E mode:
- Planner → Executor → Verifier
- Advantages: simple and easy to understand
- Disadvantages: A single Planner may be a bottleneck
Production Environment Recommendations:
- P-t-E: Priority selection, especially for entry-level scenes
- Multi-Agent: suitable for large and complex scenes
Key Metrics
1. Planning Success Rate
def calculate_planning_success_rate(state_history: List[AgentState]) -> float:
"""
規劃成功率 = (成功規劃次數) / (總規劃次數) × 100%
門檻:
- > 95%:優秀
- 80-95%:良好
- < 80%:需要改進
"""
successful_plans = sum(1 for state in state_history if state.planning_success)
total_plans = len(state_history)
return (successful_plans / total_plans) * 100
2. Execution Success Rate
def calculate_execution_success_rate(state_history: List[AgentState]) -> float:
"""
執行成功率 = (成功執行次數) / (總執行次數) × 100%
門檻:
- > 95%:優秀
- 80-95%:良好
- < 80%:需要改進
"""
successful_executions = sum(1 for state in state_history if state.execution_success)
total_executions = len(state_history)
return (successful_executions / total_executions) * 100
3. Human Intervention Rate
def calculate_human_intervention_rate(state_history: List[AgentState]) -> float:
"""
人工介入率 = (人工介入次數) / (總執行次數) × 100%
門檻:
- < 5%:優秀
- 5-15%:可接受
- > 15%:需要改進
"""
human_interventions = sum(1 for state in state_history if state.human_intervention)
total_executions = len(state_history)
return (human_interventions / total_executions) * 100
4. Average Response Time
def calculate_average_response_time(state_history: List[AgentState]) -> float:
"""
平均響應時間 = (總響應時間) / (總請求次數)
門檻:
- < 5 秒:優秀(實時場景)
- 5-15 秒:良好
- > 15 秒:需要改進
"""
total_time = sum(state.response_time for state in state_history)
total_requests = len(state_history)
return total_time / total_requests
5. Cost-Benefit Ratio
def calculate_cost_benefit_ratio(state_history: List[AgentState]) -> float:
"""
成本效益比 = (節省的成本) / (AI Agent 運營成本)
門檻:
- > 5:優秀
- 2-5:良好
- < 2:需要改進
"""
human_cost = sum(state.human_cost for state in state_history)
ai_cost = sum(state.ai_cost for state in state_history)
return human_cost / ai_cost
Deployment scenario
Scenario 1: Customer Support Automation
Deployment Mode:
- P-t-E: Planner plans the query process, Executor executes the query, and Verifier verifies the answer
- Framework: LangGraph (state management)
- Tools: knowledge base, FAQ, manual intervention
Deployment Boundary:
- Support: 100,000 - 1 million DAU
- Question Type: Inquiry, FAQ, Simple Consultation
- Not suitable: complex consultation, policy explanation
Deployment scale:
def deploy_customer_support(config: CustomerSupportConfig):
"""
客戶支持自動化部署配置
"""
config = {
"p_t_e": {
"planner": {
"model": "claude-3-opus-4.6",
"timeout": 30
},
"executor": {
"model": "claude-3-sonnet-4.6",
"tools": ["knowledge_base", "faq_search"]
},
"verifier": {
"model": "claude-3-haiku-1.5",
"threshold": 0.95
}
},
"human_intervention": {
"threshold": 0.15, # 15% 門檻
"escalation": {
"complex_query": {"length": 500, "topics": 3},
"policy_question": {"requires_confirmation": True}
}
},
"monitoring": {
"planning_success_rate": 0.95,
"execution_success_rate": 0.95,
"human_intervention_rate": 0.15,
"average_response_time": 5.0
}
}
return config
Scenario 2: Financial Transaction Agent
Deployment Mode:
- P-t-E: Planner plans trading strategies, Executor executes transactions, and Verifier verifies transaction results.
- Framework: AutoGen (programmed control)
- Tools: trading API, risk assessment, regulatory tools
Deployment Boundary:
- Trading Volume: Low to Moderate
- Risk Level: Medium Risk
- Regulatory Requirements: High
Deployment scale:
def deploy_finance_trading_agent(config: FinanceTradingConfig):
"""
金融交易 Agent 部署配置
"""
config = {
"p_t_e": {
"planner": {
"model": "claude-3-opus-4.6",
"timeout": 60,
"risk_level": "high"
},
"executor": {
"model": "claude-3-sonnet-4.6",
"tools": ["trading_api", "risk_assessment", "regulatory_tools"]
},
"verifier": {
"model": "claude-3-haiku-1.5",
"threshold": 0.99,
"human_confirmation": True
}
},
"human_intervention": {
"threshold": 0.05, # 5% 門檻(金融場景)
"confirmation_required": True # 所有交易需要確認
},
"monitoring": {
"planning_success_rate": 0.98,
"execution_success_rate": 0.99,
"human_intervention_rate": 0.05,
"average_response_time": 10.0,
"transaction_volume": "medium"
}
}
return config
Scenario 3: Code Generation Agent
Deployment Mode:
- P-t-E: Planner plans code generation tasks, Executor generates code, and Verifier checks code
- Framework: LangGraph (state management, re-planning)
- Tools: code base, testing framework, sandbox
Deployment Boundary:
- Code volume: small and medium-sized projects
- Technology stack: Python, JavaScript, Go
- Not suitable: large systems, embedded systems
Deployment scale:
def deploy_code_generation_agent(config: CodeGenerationConfig):
"""
代碼生成 Agent 部署配置
"""
config = {
"p_t_e": {
"planner": {
"model": "claude-3-opus-4.6",
"timeout": 120,
"code_scope": "medium"
},
"executor": {
"model": "claude-3-sonnet-4.6",
"tools": ["code_library", "test_framework", "sandbox"]
},
"verifier": {
"model": "claude-3-haiku-1.5",
"threshold": 0.90,
"code_quality_check": True
}
},
"human_intervention": {
"threshold": 0.10, # 10% 門檻
"code_review": True # 代碼需要審核
},
"monitoring": {
"planning_success_rate": 0.95,
"execution_success_rate": 0.90,
"human_intervention_rate": 0.10,
"average_response_time": 15.0,
"code_quality_score": 0.90
}
}
return config
Summary: Key points of production-level implementation of P-t-E
Core Points
- Control flow integrity: clear separation of Planner → Executor → Verifier
- Security: Protection measures against indirect Prompt Injection attacks
- Permission Management: Principle of least privilege, task scope tool access
- Depth of Defense: Human-in-the-Loop, dynamic re-planning, sandbox execution
- Framework selection: LangGraph (complex state), CrewAI (simple scene), AutoGen (high scalability)
Implementation Checklist
Pre-deployment checks:
- [ ] Can Planner break down tasks correctly?
- [ ] Are the Executor tool access rights correct?
- Can [ ] Verifier verify the results correctly?
- [ ] Is the threshold for manual intervention reasonable?
- [ ] Are monitoring indicators configured?
Test Check:
- [ ] Planning success rate > 95%?
- [ ] Execution success rate > 95%?
- [ ] Manual intervention rate < 15%?
- [ ] Average response time < 15 seconds?
- [ ] Cost-benefit ratio > 2?
Production Inspection:
- [ ] Is error handling complete?
- [ ] Is logging complete?
- [ ] Are monitoring alarms configured?
- [ ] Is the rollback strategy tested?
- [ ] Is the manual intervention process tested?
Next steps
ACT NOW:
- Choose a framework: LangGraph (complex state), CrewAI (simple scenario), AutoGen (high scalability)
- Deploy P-t-E architecture: Planner → Executor → Verifier
- Implement security: control flow integrity, permission management, sandbox execution
- Configuration monitoring: planning success rate, execution success rate, manual intervention rate
Short term action (1-2 weeks):
- Deploy Customer Support Automation (P-t-E + LangGraph)
- Monitoring indicators: planning success rate, execution success rate, manual intervention rate
- Optimization: manual intervention threshold, response time, cost-benefit ratio
Medium-term action (1-2 months):
- Extension: financial transaction agent, code generation agent
- Optimization: dynamic re-planning, Human-in-the-Loop
- Security: Policy update mechanism, Escalation Agent
Long term action (3-6 months):
- Extension: Multi-Agent coordination, Multi-Agent + P-t-E
- Optimization: automated monitoring and automated optimization
- Security: automated policy updates, automated Escalation
Reference source:
- arXiv:2509.08646 - Architecting Resilient LLM Agents: A Guide to Secure Plan-then-Execute Implementations
- Medium - First hand comparison of LangGraph, CrewAI and AutoGen
- Sprinklr Blog - How to Improve Customer Service ROI with AI
- GetMaxim AI - The Ultimate Checklist for Rapidly Deploying AI Agents in Production
- Galileo AI - Production Readiness Checklist for Every AI Agent
Key Metrics:
- Planning success rate > 95%: Excellent
- Execution success rate > 95%: Excellent
- Manual intervention rate < 15%: acceptable
- Average response time < 15 seconds: Good
- Cost-benefit ratio > 2: Good
Recommended Reading:
- LangGraph official documentation: https://langchain-ai.github.io/langgraph/
- CrewAI official documentation: https://docs.crewai.com/
- AutoGen official documentation: https://microsoft.github.io/autogen/