The service now also subscribes to marketplace events addressed to subscribers
(kinds 30403/31872/31871) via #p filters built from the live subscription set,
re-subscribed on every subscribe/unsubscribe. Payloads stay generic ('New offer
on your listing', 'Your offer was accepted') - never the amount or item. Verified
locally: subscribe -> offer to #p -> push attempt.
Our own keyless Bun service (not Linky's): watches relays for kind-1059 wraps
carrying the plaintext marker ["skatespots","push"] on the recipient copy,
extracts only {recipient, wrapId}, and sends a Web Push. NEVER decrypts - the
client fetches + decrypts the named wrap itself.
Endpoints: GET /health, GET /vapid-public-key, POST /auth/challenge ->
/subscribe|/unsubscribe with a one-time NIP-98 (kind 27235) challenge proof.
State is a JSON file; VAPID keys from env. Wired like the other standalone
servers (typecheck:push + check:push in npm test, deploy:push, Caddyfile +
systemd unit). Verified locally end-to-end: auth -> subscribe -> marked wrap ->
watcher -> push attempt, and proof replay rejected.
Client half (service worker, subscribe hook + Settings toggle, marker on DM
sends) is the next step.
