# Membership Tier Extension Spec

## Purpose

Define optional supply-based tiered membership pricing without breaking v1 flows.

## Tier Model

1. Tier boundaries based on total minted memberships.
2. Each tier defines currency and amount_atomic.
3. Price auto-selects by minted supply at quote time.

## Compatibility

1. Existing quote/confirm flow remains unchanged.
2. Tier metadata added to quote response (`tier_id`, `tier_label`).
3. Receipts persist tier metadata for audit.

## Guardrails

1. Floor policy still applies.
2. Tier transitions event-emitted.
3. Quotes lock tier price until expiry.