From 6394de43d4e596aaeddd2b262bb7a595679d8fbc Mon Sep 17 00:00:00 2001
From: Adam Soltys <adam@coinos.io>
Date: Mon, 14 Sep 2026 08:53:35 -0700
Subject: A zap answered by two tabs no longer reports as failed.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Every open tab of the same wallet sees every wallet-connect request. Two
hidden tabs on one laptop both tried to pay the same zap: the ASP refused
the second with "payment already in progress", and that error reached
Amethyst half a second before the first tab's preimage. A Web Lock per
request now lets one tab (or the worker) answer while the rest stay
quiet, and a device that does meet "already in progress" waits for the
sibling payment's outcome — relaying its preimage only if the payer never
speaks — instead of shouting a failure over sats that went through. The
losing side also stops writing a failed row into history for it.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QYJfZ4A1TDCEY4Foq3CApR
---
 src/ark/manager.js | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

(limited to 'src/ark')

diff --git a/src/ark/manager.js b/src/ark/manager.js
index 4dd39e4..5775d65 100644
--- a/src/ark/manager.js
+++ b/src/ark/manager.js
@@ -957,6 +957,22 @@ export class ArkManager {
 
   _expiryMargin() { return this.network === 'regtest' ? 12 : 144; }
 
+  // The settled outcome of a payment by hash, polled until the ASP's node
+  // decides or the wait runs out. For a payment another device of this
+  // wallet started (the server refuses a second HTLC for the same invoice)
+  // this is the only way to learn whether it paid.
+  async lnOutcome(paymentHash, timeoutMs = 60000) {
+    const deadline = Date.now() + timeoutMs;
+    for (;;) {
+      const res = await checkLightningPayment(this.arkUrl, hex.decode(paymentHash), false).catch(() => null);
+      if (res && res.status === 'success' && res.preimage
+          && hex.encode(sha256(hex.decode(res.preimage))) === paymentHash) return res;
+      if (res && res.status === 'failed') return res;
+      if (Date.now() >= deadline) return { status: 'pending' };
+      await new Promise((r) => setTimeout(r, 1500));
+    }
+  }
+
   lnAction(id) {
     return this.state.actions.find((a) => a.id === id && a.type.startsWith('ln-'));
   }
@@ -1140,7 +1156,12 @@ export class ArkManager {
           action.step = 'failed';
           action.error = e.message;
           this._recordExpiryRejection(action);
-          this._movement({ type: 'ln-send', amountSat: action.amountSat, status: 'failed', detail: e.message });
+          // "already in progress" means another device of this wallet is
+          // paying this very invoice — that payment's row is the history,
+          // a failed row beside it would read as a lost zap.
+          if (!/already in progress/i.test(e.message)) {
+            this._movement({ type: 'ln-send', amountSat: action.amountSat, status: 'failed', detail: e.message });
+          }
           this._save();
           return;
         }
-- 
cgit v1.2.3