Plan Review Dual Mode: CEO Thinking + Engineer Architecture — Why Use Them Separately

When designing features, most engineers skip two of the most important questions:

"Is this feature worth building?" — Most people assume the answer is "obviously yes, the requirement is already here."
"Does this architecture have hidden failure modes?" — Most people assume that if it runs, it passed.

Gstack's Plan Review handles one question each.

Two Skills, Two Completely Different Cognitive Frequencies

/plan-ceo-review and /plan-eng-review both sound like "plan review," but the questions they ask are completely different —

/plan-ceo-review is the Founder / CEO perspective:

What problem are you actually solving?
What does the user do right now? How much better is this feature than what they're already doing?
Is there a simpler solution that delivers 10x the impact?
Will this feature make the core experience more complex?

/plan-eng-review is the Engineering Manager / Tech Lead perspective:

What is the data flow? Where is state managed?
Where are the async boundaries? What are the possible race conditions?
What are the edge cases and failure modes?
How much test coverage do we need? Is there a diagram?

One steps back and asks "is it worth it"; the other pushes forward and asks "how do we do it right." Mix them together and neither works well.

What `/plan-ceo-review` Actually Asks You

Say you tell Gstack: "I want to add a product comparison feature to an e-commerce platform, letting users compare specs of three products simultaneously."

With a general AI assistant, you'd probably get a comparison table design directly.

With /plan-ceo-review, it first asks:

How do your users currently compare products? Screenshots to Notes? Opening multiple tabs manually?
Which types of users need the comparison feature most? At what stage of the purchase journey?
Is it possible the real problem is "product spec information isn't clear enough" rather than a missing comparison feature?
If "product comparison" is added but conversion rates don't improve, how would you assess this feature?

Your PM might have asked some of these questions. They might not have. But Gstack will ask them — every time, without fail. It won't let you build the right solution to the wrong problem.

What `/plan-eng-review` Actually Outputs

Same feature, switch to /plan-eng-review, and Gstack's output format changes significantly:

Architecture diagram (sequence diagram or component diagram) — visualizes your design, forcing hidden assumptions to the surface
Async boundary analysis — which parts of this feature can be asynchronous? which must be synchronous?
Failure mode list — if the database is slow, if an API fails, if the user has two tabs open simultaneously — what happens?
Test matrix — which parts need unit tests, which need integration tests, which need E2E tests

You don't necessarily need to run through all of this every time, but having a list that says "these questions are worth considering" saves a lot of time compared to starting from zero.

How to Use the Two Skills Together

Standard flow: CEO first, then Engineer.

The order is logical — if /plan-ceo-review changes the feature's definition or scope, /plan-eng-review needs to be re-run. The other way around means you might spend significant time on architecture design for a feature that isn't worth building.

Confirm "worth building" first, then confirm "how to build it right."

For small features: just run one of them.

Not every feature needs CEO thinking pressure-testing — changing a button color doesn't need "is this worth doing?"
Not every decision needs an Engineering Manager deep dive — the architecture for adding a settings field is usually obvious.

The judgment call is simple: how much pain would it cause if we got this decision wrong? The more painful, the more worthwhile it is to run Plan Review.

A Common Misuse Pattern

The most common misuse of Gstack's Plan Review is: running it after all the code is already written.

At that point, if CEO mode says "the definition of this feature should be different," what do you do? Scrap it and restart, or ignore the feedback? Neither is good.

Plan Review's timing is before the decision is locked and before you write any code — it's literally "review during the planning phase." Treat it as mandatory pre-implementation thinking, not a post-hoc checklist.

Tip: Paste Your Spec or User Story Directly

You don't need to describe the feature live in conversation with Gstack. Just paste your requirements document, user story, or design spec description, then trigger the command:

/plan-ceo-review

[Your requirements doc or user story]

It will start from your materials and analyze them through the CEO thinking framework — runs faster, and you're less likely to miss details.

Plan Review done, next step: after the code is written, how to do production-grade review and how to ship with one command.

→ Code Review and Ship: From Paranoid Review to One-Command Delivery

Back to Series Overview

This is the third stop in the Gstack series, focused on Plan Review dual mode. For the complete reading path and other post topics, return to Gstack Beginner Course.