One payment, one line: the settle path is idempotent (the mailbox push and the status poll raced past each other's step checks — a toque got two history entries), movements carry their payment hash, and the sync merge folds same-preimage lightning records into the earliest telling

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_019eA8JRq9Wr7z2fRQk99HLi

2 files changed, 21 insertions, 3 deletions

diff --git a/src/ark/manager.js b/src/ark/manager.js
index a2c69d8..cfb7436 100644
--- a/src/ark/manager.js
+++ b/src/ark/manager.js
@@ -990,16 +990,22 @@ export class ArkManager {
   }
 
   _settleLnPay(action, preimageHex) {
+    // The mailbox push and the status poll both land here, and their step
+    // checks happen BEFORE awaits — settle once, however many callers race
+    // (a hat purchase once wrote its history line twice this way).
+    if (action.step === 'done') return;
     for (const id of action.htlcVtxoIds || [action.htlcVtxoId]) {
       const htlc = this._vtxo(id);
       if (htlc) htlc.state = 'spent';
     }
     action.preimage = preimageHex;
     action.step = 'done';
-    this._movement({
+    const dup = this.state.movements.some((m) =>
+      m.type === 'ln-send' && (m.paymentHash === action.paymentHash || (m.preimage && m.preimage === preimageHex)));
+    if (!dup) this._movement({
       type: 'ln-send', amountSat: action.amountSat, status: 'complete',
       detail: action.feeSat ? `fee ${action.feeSat} sat` : undefined,
-      invoice: action.invoice, preimage: preimageHex,
+      invoice: action.invoice, preimage: preimageHex, paymentHash: action.paymentHash,
     });
     this._save();
   }
diff --git a/src/features/ark.js b/src/features/ark.js
index 3e614c4..15b7687 100644
--- a/src/features/ark.js
+++ b/src/features/ark.js
@@ -175,7 +175,19 @@ export function mergeArkStates(a, b) {
     return [...x, ...y.filter((i) => !ids.has(i.id))];
   };
   out.actions = unionById(a.actions, b.actions);
-  out.movements = unionById(a.movements, b.movements).sort((m, n) => (m.ts || 0) - (n.ts || 0));
+  // Two devices (or the push and the poll, pre-guard) can each record the
+  // SAME lightning payment under different movement ids — same preimage is
+  // the same payment, keep the earliest telling of it.
+  const seenPay = new Set();
+  out.movements = unionById(a.movements, b.movements)
+    .sort((m, n) => (m.ts || 0) - (n.ts || 0))
+    .filter((m) => {
+      if (!m.type || !m.type.startsWith('ln-') || m.status !== 'complete') return true;
+      const key = m.type + ':' + (m.paymentHash || m.preimage || m.invoice || m.id);
+      if (seenPay.has(key)) return false;
+      seenPay.add(key);
+      return true;
+    });
   const gifts = new Map((a.gifts || []).map((g) => [g.id, { ...g }]));
   for (const rg of b.gifts || []) {
     const lg = gifts.get(rg.id);