Where the charge behind the caller's latest invoice stands, and why.

<br/>Split from GET /subscription on purpose: that route runs on every page<br/>load and must stay free of provider calls, while this one costs up to three<br/>Stripe reads and is only called by the paywall while a charge the user just<br/>started has not unlocked anything yet.<br/><br/>Always 200. A user looking at a paywall gets a worse outcome from a 500 than<br/>from state: "unknown", and guessing either way is harmful: settled<br/>strands them, failed tells them to pay twice (weekly review 2026-09-28,<br/>item 1: two users looped on the paywall with no message at all, one of them<br/>for 13.6 minutes, the other forever).