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LLM & Agentic

Planner-Executor

Planner-Executor agent pattern: separating planning and execution phases for more reliable and debuggable AI agent workflows.

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Production9 min readFirst readThe Agent LoopReAct Pattern

After this section you can

  • Choose between a linear, DAG and conditional plan, and estimate a DAG’s latency from its critical path
  • Place a human gate on the plan and bind the executor to the approved version
  • Decide between planner-executor, ReAct and the hybrid, and re-plan on failure with a cap
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Planner-Executor: Divide & Conquer

ReAct decides one step at a time. A planner-executor agent writes the whole plan first, then runs it. That turns the plan into something you can validate, approve, parallelise and repair before a single side effect fires.

Key idea

Split the agent in two. A strong model writes a structured plan once; cheap models or plain code execute it. The plan is data: you check it, gate it, run independent steps in parallel, and on failure re-plan only what is left.

Think once, up front. Everything after the gate is cheap, parallel and checkable.
1 · Goal “Q3 review for Acme” 2 · Planner strong model called once 3 · Plan steps + dependencies JSON, validated 4 · Gate approve or edit the whole plan 5 · Executor runs ready steps wave by wave 6 · Result the report a step fails: send finished results + the error back, re-plan only the rest (capped) The planner never touches a tool. The executor never decides what the goal needs.

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