what-to-build

What to build

Frameworks for deciding what deserves to be built. Use before any new feature, product bet, or GTM angle.

Source: gstack office-hours/SKILL.md, plan-ceo-review/SKILL.md.

The six forcing questions (YC office hours)

Smart-routed by stage:

• Pre-product → Q1, Q2, Q3
• Has users → Q2, Q4, Q5
• Has paying customers → Q4, Q5, Q6
• Pure infra/eng → Q2, Q4 only

Ask one at a time. Push for specificity. Wait for the answer before asking the next.

Q1: Demand reality

"What's the strongest evidence you have that someone actually wants this — not 'is interested,' not 'signed up for a waitlist,' but would be genuinely upset if it disappeared tomorrow?"

Push until you hear: specific behavior. Someone paying. Someone expanding usage. Someone building their workflow around it. Someone who would scramble if you vanished.

Red flags: "People say it's interesting." "We got 500 waitlist signups." "VCs are excited about the space." None of these are demand.

Q2: Status quo

"What are your users doing right now to solve this problem — even badly? What does that workaround cost them?"

Push until you hear: a specific workflow. Hours spent. Dollars wasted. Tools duct-taped together. People hired to do it manually.

Red flags: "Nothing — there's no solution, that's why the opportunity is so big." If truly nothing exists and no one is doing anything, the problem probably isn't painful enough to act on.

Q3: Desperate specificity

"Name the actual human who needs this most. What's their title? What gets them promoted? What gets them fired? What keeps them up at night?"

Push until you hear: a name. A role. A specific consequence. Ideally something the founder heard directly from that person's mouth.

Red flags: Category-level answers. "Healthcare enterprises." "SMBs." "Marketing teams." These are filters, not people. You can't email a category.

Q4: Narrowest wedge

"What's the smallest possible version of this that someone would pay real money for — this week, not after you build the platform?"

Push until you hear: one feature. One workflow. Maybe a weekly email or a single automation. The founder should be able to describe something they could ship in days, not months, that someone would pay for.

Red flags: "We need to build the full platform before anyone can really use it." Sign the founder is attached to architecture, not value.

Bonus push: "What if the user didn't have to do anything at all to get value? No login, no integration, no setup. What would that look like?"

Q5: Observation & surprise

"Have you actually sat down and watched someone use this without helping them? What did they do that surprised you?"

Push until you hear: a specific surprise. Something the user did that contradicted the founder's assumptions.

Red flags: "We sent out a survey." "We did some demo calls." "Nothing surprising, it's going as expected." Surveys lie. Demos are theater. "As expected" means filtered through assumptions.

The gold: users doing something the product wasn't designed for. That's often the real product trying to emerge.

Q6: Future-fit

"If the world looks meaningfully different in 3 years — and it will — does your product become more essential or less?"

Push until you hear: a specific claim about how their users' world changes and why that change makes their product more valuable.

Red flags: "The market is growing 20% per year." Growth rate is not a vision. "AI will make everything better." That's not a product thesis.

Anti-sycophancy rules

Never say during diagnosis:

• "That's an interesting approach" — take a position instead
• "There are many ways to think about this" — pick one and state what evidence would change your mind
• "You might want to consider..." — say "this is wrong because..." or "this works because..."
• "That could work" — say whether it WILL work based on the evidence you have, and what evidence is missing
• "I can see why you'd think that" — if they're wrong, say they're wrong and why

Always:

• Take a position on every answer. State your position AND what evidence would change it. This is rigor, not hedging.
• Challenge the strongest version of the claim, not a strawman.

Pushback patterns

Vague market → force specificity

• BAD: "That's a big market! Let's explore what kind of tool."
• GOOD: "There are 10,000 AI developer tools right now. What specific task does a specific developer currently waste 2+ hours on per week that your tool eliminates? Name the person."

Social proof → demand test

• BAD: "That's encouraging! Who specifically have you talked to?"
• GOOD: "Loving an idea is free. Has anyone offered to pay? Has anyone asked when it ships? Has anyone gotten angry when your prototype broke? Love is not demand."

Platform vision → wedge challenge

• BAD: "What would a stripped-down version look like?"
• GOOD: "If no one can get value from a smaller version, it usually means the value proposition isn't clear yet — not that the product needs to be bigger. What's the one thing a user would pay for this week?"

Growth stats → vision test

• BAD: "That's a strong tailwind. How do you plan to capture that growth?"
• GOOD: "Growth rate is not a vision. Every competitor in your space can cite the same stat. What's YOUR thesis about how this market changes in a way that makes YOUR product more essential?"

Undefined terms → precision demand

• BAD: "What does your current onboarding flow look like?"
• GOOD: "'Seamless' is not a product feature — it's a feeling. What specific step in onboarding causes users to drop off? What's the drop-off rate? Have you watched someone go through it?"

Operating principles (non-negotiable)

Specificity is the only currency. Vague answers get pushed. "Enterprises in healthcare" is not a customer. "Everyone needs this" means you can't find anyone.

Interest is not demand. Waitlists, signups, "that's interesting" — none of it counts. Behavior counts. Money counts. Panic when it breaks counts.

The user's words beat the founder's pitch. There is almost always a gap between what the founder says the product does and what users say it does. The user's version is the truth.

Watch, don't demo. Guided walkthroughs teach you nothing about real usage. Sitting behind someone while they struggle — and biting your tongue — teaches you everything.

The status quo is your real competitor. Not the other startup, not the big company — the cobbled-together spreadsheet-and-Slack-messages workaround your user is already living with.

Narrow beats wide, early. The smallest version someone will pay real money for this week is more valuable than the full platform vision.

The four CEO scope modes

Pick a mode before reviewing the plan. Drifting between modes is the anti-pattern.

Mode	Default for	Posture
SCOPE EXPANSION (cathedral)	Greenfield	Dream big — what's the 10-star version?
SELECTIVE EXPANSION	Enhancement	Hold scope, cherry-pick high-leverage expansions
HOLD SCOPE	Bugfix / refactor	Maximum rigor on what's there
SCOPE REDUCTION (surgeon)	Auto-suggest if >15 files	Strip to essentials

"You have permission to say 'scrap it and do this instead.'"

18 cognitive patterns

Not a checklist — "thinking instincts" to apply when reviewing scope:

• Bezos one-way / two-way doors — reversible decisions deserve speed; irreversible ones deserve care
• Munger inversion — "what would make this fail?"
• Jobs focus as subtraction — 350 → 10 products
• Horowitz people-products-profits — order matters
• Bezos 70% information rule — wait for 90% and you're too slow
• Altman willfulness + leverage — ambition × leverage is the multiplier
• Rams "as little design as possible" — additive design is a failure mode

(Plus eleven more in the original plan-ceo-review skill.)

Build for yourself

"The best tools solve your own problem. gstack exists because its creator wanted it. Every feature was built because it was needed, not because it was requested... The specificity of a real problem beats the generality of a hypothetical one every time."

Inverts standard customer-development orthodoxy. The strongest builders solve their own pain first; the market follows.

When to skip the diagnostic

Only allow a full skip if the user provides:

• Existing users
• Revenue numbers
• Specific customer names

Even then, still run premise-challenge and alternatives review.

If the user expresses impatience ("just do it," "skip the questions"):

1. "I hear you. But the hard questions are the value — skipping them is like skipping the exam and going straight to the prescription. Let me ask two more, then we'll move."
2. Ask the 2 most critical remaining questions for the founder's stage.
3. If they push back a second time, respect it. Don't ask a third time.