# Single-field email capture — dev spec
Site: allbirds.com · Priority 10 · High · Effort: Low (0.5-2 days)

## Problem
The homepage email signup form asks only for an email address, which is the minimum viable field set for a cold capture, but it lacks a trust layer (e.g., privacy note, incentive) that could reduce friction and increase conversions.

## Evidence (from the live site)
> The homepage has a form with 1 input, no labels, and submit button 'Sign Up' (from inventory: forms: [{n_inputs: 1, labels: [], submit: 'Sign Up'}]).

## Current state
h1: Wildly Comfortable. Super Natural.; cta: Sign Up; notes: Single email field, no visible incentive or privacy reassurance near the form.

## Required change
h1: Wildly Comfortable. Super Natural.; cta: Sign Up for 10% Off; notes: Add a clear incentive (e.g., 'Get 10% off your first order') and a microcopy trust line (e.g., 'No spam, unsubscribe anytime') to increase signup conversion.

## Acceptance criteria
- GIVEN a first-time visitor on the affected page
- WHEN the change is live
- THEN Add a clear incentive (e.g., 'Get 10% off your first order') and a microcopy trust line (e.g., 'No spam, unsubscribe anytime') to increase signup conversion.
- AND no layout regression at 375px / 768px / 1280px
- AND the changed control is keyboard-reachable with an accessible name

## Tracking
- Fire `cro_single_field_email_capture` on interaction with the changed element
- Verify the event fires in BOTH variants before opening traffic

## Test plan
- Two-proportion z-test, 95% significance, 80% power
- 299,882 visitors per variant to detect a 5.0% relative lift
- Run at least one full business cycle; not testable at current traffic

## Rollback
Feature-flag the change; revert if the primary metric drops for 3 consecutive days.