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Agentic AI
Planning & Control Flow
Planner-Executor-Observer
Add an explicit Observer role between Planner and Executor so progress is checked against the plan instead of trusted blindly.
Intent & Description
🎯 Intent
Add an explicit Observer role between Planner and Executor so progress is checked against the plan instead of trusted blindly.
📋 Context
A team runs a Plan-and-Execute agent. The executor’s work needs to be checked against the original intent — does the cumulative output still match what the planner asked for, or has the executor wandered onto an adjacent topic? The team is willing to spend a small amount of supervision overhead to catch drift early.
💡 Solution
- Three roles: Planner produces a plan; Executor runs steps; Observer reads the cumulative result and decides: loop (continue), respond (done), or replan (start over with new evidence). - Each role has its own prompt and optionally its own model.
Real-world Use Case
- Plan quality must be checked against execution evidence rather than trusted blindly.
- Three roles (planner, executor, observer) can be defined with their own prompts.
- Observer signals (loop, respond, replan) drive the agent’s next move.
Source
Advantages
- Catches plan failure earlier than end-of-run, saving wasted tokens.
- Cleaner separation of concerns than ReAct’’s monolithic step.
Disadvantages
- Three coordinated prompts to maintain and keep aligned.
- Latency adds up if Observer runs after every single step.