Instead of prompting for code line-by-line, "Plan Mode" has the AI agent generate a detailed plan in a markdown file first. The user reviews and modifies this plan like a spec document, elevating their role from coder to architect before the AI executes the build.
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To get superior results from AI coding agents, treat them like human developers by providing a detailed plan. Creating a Product Requirements Document (PRD) upfront leads to a more focused and accurate MVP, saving significant time on debugging and revisions later on.
Counterintuitively, a model optimized for writing (GPT 5.1 High) excels at the planning stage in Cursor's "plan mode" due to its strength in logical thinking and step-by-step reasoning. For the actual code execution, switch to a coding-specific model like Sonnet.
LLMs often get stuck or pursue incorrect paths on complex tasks. "Plan mode" forces Claude Code to present its step-by-step checklist for your approval before it starts editing files. This allows you to correct its logic and assumptions upfront, ensuring the final output aligns with your intent and saving time.
The handoff between AI generation and manual refinement is a major friction point. Tools like Subframe solve this by allowing users to seamlessly switch between an 'Ask AI' mode for generative tasks and a 'Design' mode for manual, Figma-like adjustments on the same canvas.
Unlike tools that immediately generate code from a prompt, Replit first engages in a planning phase. It collaborates with the user to define the structure and goals before execution. This structured, plan-first approach makes it a far stronger and more useful tool for product managers.
Borrowing from classic management theory, the most effective way to use AI agents is to fix problems at the earliest 'lowest value stage'. This means rigorously reviewing the agent's proposed plan *before* it writes any code, preventing costly rework later on.
The ideal AI-powered engineering workflow isn't just one tool, but a fluid cycle. It involves synchronous collaboration with an AI for planning and review, then handing off to an asynchronous agent for implementation and testing, before returning to synchronous mode for the next phase.
A powerful but unintuitive AI development pattern is to give a model a vague goal and let it attempt a full implementation. This "throwaway" draft, with its mistakes and unexpected choices, provides crucial insights for writing a much more accurate plan for the final version.
The idea for "Plan Mode" came from observing power users who manually prompted the AI to outline a plan before writing code. By formalizing this user-invented "hack" into a dedicated feature, Cursor made a complex but effective workflow accessible to everyone.
To get AI agents to perform complex tasks in existing code, a three-stage workflow is key. First, have the agent research and objectively document how the codebase works. Second, use that research to create a step-by-step implementation plan. Finally, execute the plan. This structured approach prevents the agent from wasting context on discovery during implementation.
