StartupENGINEERING
Loop 1 of 5 · The Five Loops

The Problem Loop

North star: “The problem is real and worth money.

At hand
Idea

The idea itself, tested by hand.

What you hold is the tool of discovery — every loop's input, never its output. The name tells you what you're hunting; your hands tell you where you're standing.

North star

The problem is real and worth money.

Entering assumption

None — only conviction. Nothing is validated yet.

Engineering bar
Manual Delivery

None — manual delivery. The founder is the product, and that is the discipline. The cheapest evidence is bought with zero code, and it is infinitely reversible.

  1. 1 · Problem LoopManual Delivery
  2. 2 · Solution LoopDisposable Prototype
  3. 3 · Product LoopLaunchable MVP
  4. 4 · Market LoopObservable Product
  5. 5 · Fit LoopRepeatable System
The engineering bar rises only when the evidence earns it.Beyond 1: Scalable Platform — off this ladder, by design.
Exit bar
Observable evidence to leave. None of it is a feeling.
  1. 1The outcome delivered by hand at least once, with real money or real commitment changing hands.
  2. 2The workaround they already ran — in money or hours — named. A problem nobody works around is usually a problem nobody has.
  3. 3The killer technical assumption (if any) tested naked against a pass number set in advance.
  4. 4Where the product materially depends on fast-moving AI or platform capability: the rising-tide question answered in writing — when the models improve, does this product get better, or get replaced?

Earns: Problem validated. All five exit bars →

First principles
  • Software is a machine for repeating a decision cheaply.

    Which is why it is premature before you know the decision is right — and the most expensive possible medium for writing down a hypothesis.

  • Technical risk is narrower than founders fear.

    Most products have none worth the name — their risks are all on the customer side. The few that do have exactly one killer assumption, which can almost always be tested alone, cheaply, before anything is built.

  • Evidence has a price list.

    A conversation costs an hour, a manual delivery costs a week, a prototype costs a month, a build costs your runway. The craft of this loop is buying the same learning from the cheapest counter.

This loop in the AI era
Revision surface — rewritten when the wave changes. The framework beneath it doesn't move.
What changed

Your first prototype-of-thought is free: an AI assistant will pressure-test the idea, draft the pitch and simulate the skeptic before breakfast. The ground itself also moves now, so this loop gains one modern decision — the rising-tide test — before any build conversation.

What didn't change

The assistant cannot deliver your outcome to a paying customer by hand — and that, not the drafting, is this loop's evidence.

Embrace

AI as your thinking partner and skeptic.

Ignore

The release-note news cycle — the rising-tide decision replaces it with three numbers.

Decisions in this loop
Browse Problem Loop decisions in the catalogue →
Not Yet

Decisions explicitly deferred while you're in this loop. Not wrong questions — early ones. Written down, and set down.

  • Technology stack
  • Cloud provider
  • Architecture
  • Hiring
  • Agencies and quotes
  • Scalability
  • Security beyond common sense
  • Anything with a monthly invoice

Stamp your own worries with the Loop Check →

Decision skills

Free, ungated plain-text files you hand to Claude or ChatGPT. All skills →