The tradeoff gets a quiet advanced card, not a quiz: when coins run four or more hops deep, Settings grows an "exit cost" card naming today's trustless-exit price and offering a one-tap renewal that flattens the history — invisible to everyone whose coins are shallow

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

2 files changed, 33 insertions, 1 deletions

diff --git a/src/features/ark.js b/src/features/ark.js
index 269cfb9..66eef18 100644
--- a/src/features/ark.js
+++ b/src/features/ark.js
@@ -1466,6 +1466,33 @@ export function arkFeature(ctx) {
     }
   }
 
+  // The exit-cost tradeoff, surfaced only when it's real: every off-chain
+  // hop a coin accumulates makes its trustless exit one on-chain transaction
+  // more expensive; a renewal flattens the history back to a single hop.
+  // Most users never need to think about this — the card only appears once
+  // coins run deep enough for the difference to matter.
+  const EXIT_DEPTH_ADVISORY = 4;
+  function exitDepthCard() {
+    if (!arkAvailable() || wallet.watchOnly || !ark || !ark.state) return null;
+    const spend = (ark.state.vtxos || []).filter((v) => v.state === 'spendable');
+    if (!spend.length) return null;
+    let depth = 0;
+    for (const v of spend) { try { depth = Math.max(depth, ark._decoded(v).genesis.length); } catch {} }
+    if (depth < EXIT_DEPTH_ADVISORY) return null;
+    let exitFee = 0; try { exitFee = estimateExitFeeSat(ark); } catch {}
+    let renewFee = 0; try { renewFee = ark.refreshFee(spend, ark._tipH || 0); } catch {}
+    return h('div', { class: 'card col', style: 'gap:8px' },
+      h('h3', {}, t('arkDepthTitle')),
+      h('p', { class: 'small muted', style: 'margin:0' },
+        t('arkDepthBody', { d: String(depth), fee: fmtAmount(exitFee), renew: renewFee > 0 ? fmtAmount(renewFee) + ' sats' : t('arkDepthFree') })),
+      h('button', { class: 'btn-block', disabled: !!ui.arkBusy, onClick: () => {
+        // fire and let the round machinery carry it — rounds can be an hour out
+        ark.refresh(spend.map((v) => v.id)).catch((e) => toast(e.message));
+        toast(t('arkDepthRenewed'));
+        render();
+      } }, t('arkDepthBtn')));
+  }
+
   function autoWithdrawCard() {
     if (!arkAvailable() || wallet.watchOnly) return null;
     const st = awState();
@@ -2325,7 +2352,7 @@ export function arkFeature(ctx) {
     // swaps feature): the ASP pays invoices natively over ark.
     canLnPay() { return arkAvailable() && !wallet.watchOnly && !!(ark && ark.info); },
     lnSpendableSat() { const b = arkBalance(); return b ? b.spendableSat : 0; },
-    settingsCards() { return [autoWithdrawCard()]; },
+    settingsCards() { return [autoWithdrawCard(), exitDepthCard()]; },
     // The onboarding wizard's top-up step borrows the board form wholesale.
     arkBoardForm() {
       if (!arkAvailable() || wallet.watchOnly) return null;
diff --git a/src/i18n.js b/src/i18n.js
index a0a251d..624ca15 100644
--- a/src/i18n.js
+++ b/src/i18n.js
@@ -199,6 +199,11 @@ const STR = {
     onbBoardTitle: 'Top up Spending',
     onbBoardBody: 'Move some sats from Savings into Spending — payments there are instant, with no mining fees.',
     topUpFromSavings: 'Top up from Savings',
+    arkDepthTitle: 'Advanced · exit cost',
+    arkDepthBody: 'Your coins’ off-chain history is {d} hops deep. A trustless exit would currently cost about {fee} sats in mining fees — each hop is one more on-chain transaction. Renewing now flattens the history back to a single hop for {renew}.',
+    arkDepthFree: 'free',
+    arkDepthBtn: 'Renew now',
+    arkDepthRenewed: 'Renewal requested — your coins flatten when the next round completes.',
     arkUniUneconomical: 'A trustless on-chain exit would cost about {fee} sats in mining fees — more than the {n} sats it would move, so it isn’t offered. For a balance this size, send it out over Lightning instead: no mining fees at all.',
     arkUniFallbackBody: 'The server didn’t cooperate, but your money can still move without it: your whole Spending balance exits to Savings on-chain. It takes about a day, and roughly {fee} sats of mining fees will be paid from Savings. Funds land in Savings — send them on from there once it completes.',
     arkUniFallbackShort: 'Savings holds {have} sats — about {need} sats are needed for the mining fees. Top up Savings first.',