Fix NWC encryption fallback handling

js/payments/nwcClient.js

@@ -341,16 +341,21 @@ function createNip44Encryption(context) {
 
 function getWalletSupportedEncryption(infoEvent) {
   if (!infoEvent || !Array.isArray(infoEvent.tags)) {
-    return ["nip04"];
+    return { schemes: [], explicit: false };
   }
 
   const tag = infoEvent.tags.find((entry) => Array.isArray(entry) && entry[0] === "encryption");
   if (!tag || typeof tag[1] !== "string") {
-    return ["nip04"];
+    return { schemes: [], explicit: false };
   }
 
   const values = normalizeSpaceSeparatedValues(tag[1]);
-  return values.length ? values : ["nip04"];
+  if (!values.length) {
+    return { schemes: [], explicit: false };
+  }
+
+  const schemes = Array.from(new Set(values));
+  return { schemes, explicit: true };
 }
 
 function getEncryptionCandidates(context) {
@@ -487,31 +492,35 @@ async function ensureEncryption(context) {
     }
   }
 
-  const walletSchemes = getWalletSupportedEncryption(infoEvent);
+  const { schemes: walletSchemes } = getWalletSupportedEncryption(infoEvent);
   const candidates = getEncryptionCandidates(context).filter((candidate) => {
     return !state.unsupported.has(candidate.scheme);
   });
 
-  for (const candidate of candidates) {
-    if (walletSchemes.includes(candidate.scheme)) {
-      context.encryption = candidate;
-      return candidate;
-    }
+  const compatibleCandidates = walletSchemes.length
+    ? candidates.filter((candidate) => walletSchemes.includes(candidate.scheme))
+    : candidates;
+
+  if (compatibleCandidates.length) {
+    const selected = compatibleCandidates[0];
+    context.encryption = selected;
+    return selected;
   }
 
-  const fallback = candidates.find((candidate) => candidate.scheme === "nip04");
-  if (fallback) {
-    console.warn(
-      "[nwcClient] Falling back to nip04 encryption despite wallet not advertising support."
-    );
-    context.encryption = fallback;
-    return fallback;
-  }
-
-  if (walletSchemes.includes("nip04")) {
+  if (
+    walletSchemes.includes("nip04") &&
+    !candidates.some((candidate) => candidate.scheme === "nip04")
+  ) {
     throw new Error("NostrTools.nip04.encrypt is not available.");
   }
 
+  if (walletSchemes.length) {
+    const message = `Wallet advertises unsupported encryption schemes: ${walletSchemes.join(", ")}.`;
+    const error = new Error(message);
+    error.code = "UNSUPPORTED_ENCRYPTION";
+    throw error;
+  }
+
   throw new Error("No compatible wallet encryption scheme available.");
 }
 
@@ -983,4 +992,5 @@ export const __TESTING__ = Object.freeze({
   ensureActiveState,
   buildPayInvoiceParams,
   getActiveState: () => activeState,
+  ensureEncryptionForContext: ensureEncryption,
 });

tests/nwc-client.test.mjs

@@ -48,6 +48,21 @@ await (async () => {
     getPublicKey() {
       return "c".repeat(64);
     },
+    nip44: {
+      v2: {
+        async encrypt(plaintext, key) {
+          return `nip44:${key}:${plaintext}`;
+        },
+        async decrypt(ciphertext, key) {
+          return `nip44:${key}:${ciphertext}`;
+        },
+        utils: {
+          getConversationKey(secretBytes, pubkey) {
+            return `key-${pubkey}-${secretBytes.length}`;
+          },
+        },
+      },
+    },
   };
 
   const walletPubkey = "b".repeat(64);
@@ -75,6 +90,61 @@ await (async () => {
   assert.equal(reparsed.secretKey, secretKey);
   assert.equal(reparsed.queryParams.lud16, lud16);
 
+  context.infoEvent = {
+    kind: 13194,
+    tags: [["encryption", "nip44_v2"]],
+  };
+
+  const encryption = await __TESTING__.ensureEncryptionForContext(context);
+  assert.equal(encryption.scheme, "nip44_v2");
+  const encrypted = await encryption.encrypt("payload");
+  assert.match(encrypted, /^nip44:key-b{64}-/);
+
+  resetWalletClient();
+})();
+
+await (async () => {
+  resetWalletClient();
+
+  window.NostrTools = {
+    getPublicKey() {
+      return "c".repeat(64);
+    },
+    nip04: {
+      async encrypt() {
+        return "nip04";
+      },
+      async decrypt() {
+        return "nip04";
+      },
+    },
+  };
+
+  const walletPubkey = "b".repeat(64);
+  const secretKey = "a".repeat(64);
+  const relays = ["wss://relay.one.example"];
+  const uri =
+    `nostr+walletconnect://${walletPubkey}` +
+    `?relay=${encodeURIComponent(relays[0])}` +
+    `&secret=${secretKey}`;
+
+  const context = ensureActiveState({ nwcUri: uri });
+  context.infoEvent = {
+    kind: 13194,
+    tags: [["encryption", "nip44_v2"]],
+  };
+
+  await assert.rejects(
+    () => __TESTING__.ensureEncryptionForContext(context),
+    (error) => {
+      assert.match(
+        error?.message || "",
+        /Wallet advertises unsupported encryption schemes: nip44_v2\./
+      );
+      return true;
+    }
+  );
+
   resetWalletClient();
 })();