Never silently drop an NWC request addressed to us

A request that fails to decrypt was returning without a reply, on the theory
that undecryptable traffic wasn't ours. But the event is addressed to this
connection's service key and signed by its client key — it IS ours, so a
failure there is our bug, and dropping it looks exactly like the wallet being
offline. That is why Amethyst spun with no way to tell why.

Now it logs the reason, records it for the Settings card, and replies with an
INTERNAL error (in both schemes, in case scheme detection was itself wrong) so
the client fails fast. The card also shows the last request accepted, so the
listener can be seen working without devtools.

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

1 files changed, 30 insertions, 1 deletions

diff --git a/src/features/nwc.js b/src/features/nwc.js
index e0af5da..935b8cb 100644
--- a/src/features/nwc.js
+++ b/src/features/nwc.js
@@ -208,6 +208,8 @@ export function nwcFeature(ctx) {
   }
 
   const handled = new Set(); // request ids seen this session (replay guard)
+  let lastError = null;      // surfaced in the Settings card
+  let lastSeen = null;       // last request we accepted, ditto
 
   async function onRequest(c, ev) {
     if (ev.kind !== REQ_KIND) return;
@@ -223,12 +225,31 @@ export function nwcFeature(ctx) {
     let req;
     try {
       req = JSON.parse(await decrypt(scheme, hex.decode(c.serviceSk), ev.pubkey, ev.content));
-    } catch { return; } // undecryptable: not for us
+    } catch (e) {
+      // This used to return silently, on the theory that undecryptable traffic
+      // simply wasn't for us. But the event is addressed to this connection's
+      // service key and signed by its client key — it IS for us, so a failure
+      // here is a bug in our own handling and must be loud. Silently dropping
+      // it looks identical to the wallet being offline.
+      const why = `${scheme} decrypt failed: ${e && e.message ? e.message : e}`;
+      console.error('nwc:', why, { ev: ev.id, scheme, from: ev.pubkey.slice(0, 12) });
+      lastError = { at: Date.now(), why, scheme, evId: ev.id };
+      // Reply so the client fails fast instead of spinning forever. Try the
+      // other scheme for the reply in case our scheme detection was wrong.
+      await reply(c, ev, scheme, { result_type: 'error', ...errRes('INTERNAL', why) })
+        .catch(() => {});
+      if (scheme === 'nip04') {
+        await reply(c, ev, 'nip44_v2', { result_type: 'error', ...errRes('INTERNAL', why) })
+          .catch(() => {});
+      }
+      return;
+    }
     const { method, params = {} } = req || {};
     if (!METHODS.includes(method)) {
       return reply(c, ev, scheme, { result_type: method, ...errRes('NOT_IMPLEMENTED', 'method not supported') });
     }
     updateConn(c.id, { lastUsed: Date.now() });
+    lastSeen = { at: Date.now(), method, scheme };
 
     try {
       const out = await handle(c, method, params);
@@ -417,6 +438,14 @@ export function nwcFeature(ctx) {
       h('h3', { class: 'row gap6', style: 'align-items:center' }, '🔌', t('nwcTitle')),
       h('p', { class: 'small muted', style: 'margin:0' }, t('nwcDesc')),
       h('div', { class: 'small faint' }, t('nwcTabWarning')),
+      lastError
+        ? h('div', { class: 'notice err', style: 'font-size:11px' },
+            `${new Date(lastError.at).toLocaleTimeString()} — ${lastError.why}`)
+        : null,
+      lastSeen
+        ? h('div', { class: 'small faint' },
+            `last request: ${lastSeen.method} (${lastSeen.scheme}) at ${new Date(lastSeen.at).toLocaleTimeString()}`)
+        : null,
       ...list.map((c) => {
         const { spent } = spendRoom(c);
         return h('div', { class: 'col', style: 'gap:4px;border-top:1px solid var(--border,rgba(128,128,128,.2));padding-top:8px' },