Add Nostr Wallet Connect (NIP-47) — hal as a wallet service

Other apps can connect over nostr and pay from this wallet without touching
its keys, within a per-payment and daily budget the user sets, revocable at
any time. hal holds no native Lightning balance, so every operation runs over
Ark: pay_invoice takes the swap bridge when configured and falls back to the
ASP's lightning-send, make_invoice mints on the ASP. NWC availability
therefore tracks Ark availability.

- kinds 13194/23194/23195, nip44_v2 and nip04, replying in whichever scheme
  the request used; every request gets a reply so clients never hang
- each connection gets its own service keypair, so revoking one can't affect
  the others and none is tied to the user's nostr identity
- budgets are checked BEFORE spending, not reconciled after
- requests are ignored unless signed by that connection's client key, and
  replayed/stale events (>120s) can't re-trigger a payment
- Settings card to create, show (URI + QR) and revoke connections, and it
  says plainly that this only works while a tab is open

tools/nwc-test.js drives it as a real client: both encryption schemes, budget
refusal with a genuine over-limit invoice, unsupported-method errors, and a
request from an unauthorized key being ignored.

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

1 files changed, 13 insertions, 0 deletions

diff --git a/src/nostr.js b/src/nostr.js
index 407663c..652c579 100644
--- a/src/nostr.js
+++ b/src/nostr.js
@@ -11,6 +11,7 @@
 
 import * as nip06 from 'nostr-tools/nip06';
 import * as nip44 from 'nostr-tools/nip44';
+import * as nip04 from 'nostr-tools/nip04';
 import { wrapEvent as nip17WrapEvent } from 'nostr-tools/nip17';
 import { getPublicKey, finalizeEvent, generateSecretKey } from 'nostr-tools/pure';
 import { decode as nip19decode, npubEncode } from 'nostr-tools/nip19';
@@ -24,6 +25,11 @@ const pool = new SimplePool();
 
 // --- locking a gift to a recipient's Nostr key ---------------------------
 // An npub or 64-hex nostr pubkey → hex, or null if it isn't one.
+// NIP-47 wallet services sign with their own per-connection key and must
+// speak whichever encryption the client asked for, so export both schemes.
+export { nip04, nip44 };
+export { getPublicKey, finalizeEvent, generateSecretKey };
+
 export function parseNostrPubkey(input) {
   const s = (input || '').trim();
   if (/^[0-9a-f]{64}$/i.test(s)) return s.toLowerCase();
@@ -212,6 +218,13 @@ export class NostrSync {
     } catch { return null; }
   }
 
+  // Publish an event signed by some other key (the NWC service key). The
+  // wallet's own key must not sign wallet-service traffic — connections are
+  // revocable and shouldn't be tied to the user's nostr identity.
+  async publishSigned(evt, relays = this.relays) {
+    try { await Promise.allSettled(pool.publish(relays, evt)); return true; } catch { return false; }
+  }
+
   // Fetch events matching a filter from the relays (best-effort).
   async fetchEvents(filter, maxWait = 5000) {
     try { return await pool.querySync(this.relays, filter, { maxWait }); } catch { return []; }