The deep viral-design pass — for features that already passed the Quick Test and deserve real scrutiny before you build.
The Quick Test is a 60-second gut-check you run in a meeting or a ticket. It is cheap on purpose, and cheap things miss things. The Feature Review is what you run after the gut-check passes and before a single engineer is committed — the last moment the loop costs nothing to redesign.
A feature review is not bureaucracy. It is the difference between a loop you designed and one you hoped for.
This is Part 03b of the Native Viral Loop Framework. Everything here serves one principle from the hub: a viral loop is an architecture decision, not a growth hack. The review is where that decision gets made deliberately, on paper, while it is still free to change your mind.
The number you are designing for is the Multiplier — reach × conversion × speed. The Feature Review takes that target apart into the five levers you can actually act on, and asks the hard questions inside each one:
The Multiplier is a product, not a sum. A zero in any bucket multiplies the whole loop to near zero — so an empty bucket is a finding, not a footnote. Work the five accordions below as your spec. The math behind them lives in the Multiplier; you turn the answers into numbers with the K-Factor Calculator.
Open each lever. Answer in writing, with specifics — a screen, a number, a path — not adjectives. A question you cannot answer concretely is the gap to fix before you build.
Reading the gap: if you can't name a moment that goes outside the product on its own, you don't have a weak loop — you have no loop. Don't optimise the other four buckets; go back and design a trigger, or accept this feature simply doesn't carry one.
Reading the gap: weak reach is usually fixable without touching the trigger — widen the share surface, make the artefact public, fix the link preview. If reach is structurally 1:1, your ceiling is low; decide if that's acceptable before you build.
Reading the gap: this is the bucket most features fail, and the most expensive to discover after launch. A blank here is not a polish item — it is the thing quietly multiplying your loop toward zero. Fix it before anything else.
Reading the gap: conversion gaps look small and compound brutally — three steps at 70% each leaves you 34%. Cut steps, defer the signup, and test the path on the device people actually use before you ship.
Reading the gap: a slow loop isn't a failed loop — it's an untuned one. Shorten the cycle (fewer waits, instant artefacts, real-time delivery) before you touch reach or conversion, because speed compounds harder than either. Then quantify it with the K-Factor Calculator.
In eighteen years of shipping products I have watched the same thing happen over and over: a team gut-checks a feature, agrees "yeah, that could go viral," and ships. Three weeks later the loop is flat and nobody can say which bucket failed — because nobody wrote them down.
The Feature Review fixes that for the cost of an hour. It forces the loop out of your head and onto paper, lever by lever, while changing it is still free. Most features die quietly in Value-on-arrival — a signup wall in front of the value — and that's a one-line fix on paper and a rebuild after launch. That gap between "we hoped" and "we designed" is the entire return on this hour.
Not every feature survives the review, and that is the point. A feature with no trigger isn't a failure of the review — it's information you got for free. New to the vocabulary? The plain-English guide to what a viral loop is sets the terms; the Multiplier sets the target.