# PRD — Review & Edit: Substitution Structure

## Problem statement
Customers want a single place to review and edit which of their order items can be substituted before picking begins. The open question is how to structure a full order of items so customers can find an item, understand which items will/won't be replaced, and adjust preferences with confidence.

## Goals
1. Let customers set and change substitution preferences across the whole order in one surface
2. Make it obvious which items will be replaced, which won't, and which are ineligible
3. Minimize effort to locate and change a single item's preference

## Non-goals
1. The per-item substitution prompt at cart-add (handled elsewhere — "Customer Choice")
2. The recovery / Accept-Reject flow after picking (handled in Project 1)

## User stories
- As a customer, I want to see every item's substitution status in one place so I can review before picking
- As a customer, I want to change one item from "replace" to "don't replace" without hunting
- As a customer, I want to understand which items can't be substituted at all (e.g. alcohol) so I'm not surprised

## Constraints
- Mobile-first (375px)
- Must reuse existing design-system components and accessibility patterns
- No new backend API for this surface — work with the item/eligibility data already available

## Success metrics
- Count-comprehension accuracy ≥ 70%
- Locate-an-item success ≥ 80%
- Confidence & clarity ≥ 4/5

## Open questions
- Should ineligible items be shown inline or in a separate group?
- Are "eligible / ineligible" the right labels, or should they describe the outcome the customer cares about?