Zappable offer codes and per-name Lightning offers

CLINK offers (noffer): every wallet gets a static offer keypair (synced
across devices, first-minted wins) answering kind-21001 invoice
requests — from open tabs and from the service worker while closed,
which mints against the mirrored state (the record now carries chain-4
and chain-5 key windows) and raises an open-to-receive notification.
Zap requests ride along and their kind-9735 receipts publish once the
payment is claimed. The code is shown in the payment-address card for
pasting into a Nostr profile; the notifier watches and relays kind
21001 alongside NWC.

Payment names also gain a Lightning offer: the registrar creates a
BOLT 12 offer per name on the node and appends lno= to the DNS record;
a settle-forwarder pushes each received payment on to the name's ark
destination from a small float wallet (custody window: seconds between
Lightning settle and the ark send).

Name resolution now runs full client-side DNSSEC validation
(src/dnssec.js): binary DoH, root-anchor chain walk, RSA + ECDSA via
WebCrypto — the resolver is untrusted transport, verified against live
signed zones including the canonical BIP-353 test name.

Co-Authored-By: Claude Fable 5 <[email protected]>

1 files changed, 15 insertions, 4 deletions

diff --git a/src/nwc-bg.js b/src/nwc-bg.js
index f539e45..af0bb6d 100644
--- a/src/nwc-bg.js
+++ b/src/nwc-bg.js
@@ -79,20 +79,31 @@ export async function allBgs() {
 // cannot derive keys, so its allocations must land inside this window.
 export const BG_KEY_LOOKAHEAD = 25;
 
-// { ark } endpoints, the manager state to mirror, and a keyFor(index) derive
-// function (the caller owns the account node — it never enters this module).
-export function buildBg({ ark, mgrState, keyFor, connections }) {
+// { ark } endpoints, the manager state to mirror, and a keyFor(chain, index)
+// derive function (the caller owns the account node — it never enters this
+// module). Chain 3 covers coins + change, chain 4/0 the mailbox, chain 5 a
+// window of receive preimages — everything the worker needs to pay AND to
+// mint invoices while the app is closed.
+export function buildBg({ ark, mgrState, keyFor, connections, offer }) {
   const keys = {};
   const idx = new Set((mgrState.vtxos || []).filter((v) => v.state !== 'spent').map((v) => v.keyIndex));
   for (let i = 0; i < BG_KEY_LOOKAHEAD; i++) idx.add((mgrState.nextKeyIndex || 1) + i);
   idx.add(0); // the receive-address key: mailbox/refund defaults land on it
-  for (const i of idx) keys[String(i)] = keyFor(i);
+  for (const i of idx) keys[String(i)] = keyFor(3, i);
+  const keys5 = {};
+  for (let i = 0; i < 15; i++) {
+    const n = (mgrState.nextLnRecvIndex || 0) + i;
+    keys5[String(n)] = keyFor(5, n);
+  }
   return {
     v: 3,
     updated: Date.now(),
     ark,
     mgr: mgrState,
     keys,
+    keys5,
+    key4: keyFor(4, 0),
+    offer: offer || null, // { sk, pk } — the CLINK offer service keypair
     connections: (connections || []).map((c) => ({
       id: c.id, servicePk: c.servicePk, serviceSk: c.serviceSk, clientPk: c.clientPk,
       maxSat: c.maxSat, dailySat: c.dailySat,