One of four. The design playbook governs how a thing looks, the architecture playbook governs how it's arranged, the copy playbook governs what it says. This one governs whether it should exist at all.
What change you're causing, and what you actually know versus what you're guessing.
Conversations that produce evidence instead of flattery. Where openings come from.
What has to be true, which belief kills you fastest, and the cheapest test for it.
What people will pay, found early enough to still change what gets built.
Everything in the system hangs off four levels. Draw it, keep it visible, and put every new thing you hear somewhere on it. The tree's real job isn't organisation; it's exposure. A tree that never changes means nobody's learning.
Four pages, one per stage, each doing a job the others don't. Most people arrive claiming a later stage than they're standing on; the tell is the evidence, and if the answer to "what did they say" is a summary rather than a quote, they're one stage back from where they think. Every time.
Four levels, and the routing logic that works out which one you're actually standing on. Carries the refusals that stop the sequence running backwards.
Open → InterviewsRefuse the generality, get one specific incident, ask what actually happened. Praise, Vapor and Wishlist are not data, and only The Give counts as a signal.
Open → TestingWhat has to be true, and which belief kills you fastest. Five tests, the Walk-Through, the Autopsy, the Kill Grid, and designing every test for the no.
Open → MoneyWhat people will pay, found before the build decides for you. Overbuilt, Underpriced, Overlooked, Unwanted, and the Yardstick they're secretly measuring you against.
Open →Hard rules, and the reason this playbook exists as a system rather than a reading list. Say them plainly, once, then help anyway with the caveat attached. The point isn't to withhold help; it's to name what the help is worth at that stage, so nobody mistakes a guess dressed as an answer for the real thing.
Willingness-to-pay runs on people who have the problem. Run it earlier and you get a number that describes nobody, and worse, you get confidence.
If you can't say what would have to be true, you can't say what would prove you wrong, so nothing that happens next will change your mind.
Guesses can live on the tree. They just can't sit there unlabelled, quietly collecting the authority of evidence.
The only signals that count cost something: time, reputation, or money. Everything else records as a zero, not a maybe.
Four now, and they run in order. This one comes first; it decides whether there's anything worth designing, arranging, or writing about.
How a thing looks. Eighteen styleguide pages, from tokens through to accessibility.
Open →How it's arranged. Governs the shape of all four playbooks, including this one.
Open →What it says. Thirteen living pages, in the order you actually write in.
Open →Eight books filtered. A book earns inclusion only if it does a job the system doesn't already cover and survives translation into this vocabulary. Sources are credited as inspiration and never reproduced. The rejections are listed on purpose; a provenance table that only shows the wins is marketing.
| Source | What it gave | What changed |
|---|---|---|
| Continuous Discovery Habits Teresa Torres | The tree, the assumption layer, the past-tense autopsy, the Harm questions | Reshaped for pre-launch and solo work; Torres assumes a product trio with a running product and an assigned outcome |
| The Mom Test Rob Fitzpatrick | Interview discipline, the worthless-input taxonomy, commitment as the only real signal | Renamed Praise / Vapor / Wishlist and The Give; merged with Torres where both arrive at the same move |
| Monetizing Innovation Ramanujam & Tacke | Willingness-to-pay first, the four failure modes, segment before you configure | Renamed Overbuilt / Underpriced / Overlooked / Unwanted; features sorted as Pullers / Padding / Poison |
| How to Price Effectively Utpal Dholakia | Reference prices | Renamed the Yardstick. Adopted selectively, the rest overlaps Monetizing Innovation and loses |
| Hooked Nir Eyal | The internal-trigger hunt, kept as The Itch | Compulsion framing dropped entirely, and the brake installed next to it as Harm |
| Impossible to Ignore Carmen Simon | Memory and recall | Rehomed to the Copy Playbook. Real book, wrong shelf. |
| Instant Appeal Vicki Kunkel | — | Rejected. Thin, anecdotal, dated evolutionary psychology. |
| Problem Solving For Every Problem Thinknetic | — | Rejected. A catalog of techniques with no selection rule. |