Single Purpose policy — paywall as post-quota upgrade offer — compliant design?

[Jane Palma]

Hi all,

My TTS extension was rejected under Red Magnesium (Single Purpose).
Reviewer flagged "iframe with external URL for paywall" as additional
functionality on top of the stated "AI Voice generator" purpose.

Before resubmitting, I'd like to sanity-check the planned design:

- Every user gets 10 minutes/day of AI voice playback, free, no sign-in
- Browser's built-in Web Speech API voices remain unlimited and free
- The iframe (payment UI from a third-party paywall provider) appears
  only as an upgrade offer after a non-subscribed user exhausts the
  daily AI quota
- The paid tier unlocks more minutes of the same feature — not a
  separate service

Two questions:

1. Is this design compliant, given the paywall governs access to more
   of the same single feature and is gated behind quota exhaustion
   (unreachable during a standard review session)?

2. If the iframe is still a concern, would replacing it with a native
   popup UI + chrome.tabs.create() opening the checkout URL in a new
   tab resolve it?

Appreciate any guidance from those who've dealt with similar Single
Purpose rejections.