Plan-and-Execute

The agent receives a goal, decomposes it into a sequence of steps and executes them one by one. Planning and execution are two distinct phases, with no re-reasoning in between. The plan is followed religiously: predictable, fast and auditable upfront, rigid when the world changes mid-execution.

The working tradeoff: predictable cost and upfront auditability on one side, rigidity and blindness to change on the other. The hybrid keeps the plan's economics and adds re-planning checkpoints exactly where surprises are most likely.

The mechanics

The architecture describes an agent which generates a complete plan upfront and then executes sequentially. Planning and execution are two distinct phases, which implies that there are no re-reasoning steps in between. In practice the agent receives a goal, decomposes it into a sequence of steps and then executes those steps one by one. Each step completes before the next begins. The plan is followed religiously.

Strengths

The positives of this approach are the predictable cost, since token consumption is forecastable because planning happens once and no repeated reasoning cycles burn tokens between steps. It is also faster execution-wise because there are no pause-and-rethink steps. Lastly, it is auditable because the full plan is visible before anything executes. A human can review the plan, approve it and know exactly what will happen. This maps cleanly to governance requirements.

Weaknesses

On the other hand there are downsides, such as the fact that the architecture is rigid by design. If something unexpected happens during one of the steps the agent has no mechanism to adapt, and the remaining steps execute against the bad assumptions of a plan that was wrong all along. The approach is also blind to change, which means that if the environment shifts mid-execution the agent does not notice and it follows the plan regardless.

Where it fits

The architecture is best used in stable environments and well-defined workflows with predictable conditions. This includes back-office processes, batch operations and analytical workflows where changes do not happen often. It is also a good option for use cases where cost control and auditability matter more than adaptability. A practical and nuanced approach for some implementations is to add re-planning checkpoints at critical steps. This is a hybrid approach that keeps the cost efficiency while it introduces adaptability where it matters the most.