Show a draw animation and win/lose reveal on the user dashboard

When the round leaves "open" (closing/drawing/paying_out), the round
card swaps its timer for a spinning "Estrazione del vincitore in
corso…" state instead — bets are already rejected server-side once the
round isn't open, this just reflects that visually. Once winner_user_id
is set AND at least draw_animation_seconds has elapsed since the round
started closing (client-tracked per round_id), it reveals "🎉 Hai
vinto! +N PLM" (compared against the user's own id from /users/me) or
"Non hai vinto questa volta.", with a success toast on a win. The
result stays on screen through the cooldown gap and only clears once a
genuinely new round opens (tracked via activeResultRoundId), not the
instant the old round has no active status.

Polling is now dynamic (setTimeout-chained, not setInterval): 3s while
the round is closing/drawing/paying_out for a responsive reveal, 15s
while open.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/static/index.html

@@ -140,6 +140,19 @@
 
   .hidden { display: none !important; }
 
+  .draw-state { display: none; text-align: center; padding: 8px 0 4px; }
+  .draw-state.active { display: block; }
+  .draw-spinner {
+    width: 40px; height: 40px; margin: 0 auto 10px;
+    border: 3px solid var(--color-border); border-top-color: var(--color-primary);
+    border-radius: 50%; animation: spin 900ms linear infinite;
+  }
+  @keyframes spin { to { transform: rotate(360deg); } }
+  .draw-state .draw-label { font-weight: 600; font-size: 0.95rem; }
+  .draw-result { font-size: 1.05rem; font-weight: 700; padding: 6px 0; }
+  .draw-result.win { color: var(--color-success); }
+  .draw-result.lose { color: var(--color-muted-foreground); }
+
   #toast-container {
     position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%);
     display: flex; flex-direction: column; gap: 8px; z-index: 100; width: calc(100% - 40px); max-width: 440px;
@@ -201,11 +214,11 @@
   </div>
 
   <div class="card">
-    <div class="row-between">
+    <div class="row-between" id="round-normal-row">
       <h2 id="round-title">Round —</h2>
       <span class="mono" id="round-timer" style="font-size:1.1rem;font-weight:700">--:--</span>
     </div>
-    <div class="row-between" style="margin-top:10px">
+    <div class="row-between" style="margin-top:10px" id="round-stats-row">
       <div>
         <div class="hint" style="margin-bottom:2px">Giocatori</div>
         <span class="mono" id="round-players">—</span>
@@ -215,6 +228,13 @@
         <span class="mono" id="round-jackpot">—</span> <span class="balance-unit">PLM</span>
       </div>
     </div>
+
+    <div class="draw-state" id="draw-state">
+      <div class="draw-spinner"></div>
+      <div class="draw-label">Estrazione del vincitore in corso…</div>
+    </div>
+
+    <div class="hidden" id="draw-result"></div>
   </div>
 
   <nav class="menu" aria-label="Sezioni">
@@ -337,7 +357,7 @@ function switchPanel(name) {
 
 let roundCloseAt = null;
 let roundTimerInterval = null;
-let roundPollInterval = null;
+let roundPollTimeout = null;
 
 const ROUND_STATUS_LABELS = {
   open: 'aperto',
@@ -346,6 +366,15 @@ const ROUND_STATUS_LABELS = {
   paying_out: 'pagamento in corso',
 };
 
+const DRAWING_STATUSES = ['closing', 'drawing', 'paying_out'];
+
+// Per round_id: when we first saw it enter a drawing status (client clock), and
+// whether the win/lose result has already been shown for it. Local-only state,
+// not persisted — a page reload just re-derives it from the next poll.
+const drawStartedAt = {};
+const revealedRounds = new Set();
+let activeResultRoundId = null; // round_id whose win/lose result is on screen, if any
+
 function updateRoundTimer() {
   const el = document.getElementById('round-timer');
   if (!roundCloseAt) { el.textContent = '--:--'; return; }
@@ -355,6 +384,30 @@ function updateRoundTimer() {
   el.textContent = mm + ':' + ss;
 }
 
+function showDrawingState() {
+  document.getElementById('round-normal-row').classList.add('hidden');
+  document.getElementById('round-stats-row').classList.add('hidden');
+  document.getElementById('draw-state').classList.add('active');
+  document.getElementById('draw-result').classList.add('hidden');
+}
+
+function showResultState(html, cls) {
+  document.getElementById('round-normal-row').classList.add('hidden');
+  document.getElementById('round-stats-row').classList.add('hidden');
+  document.getElementById('draw-state').classList.remove('active');
+  const el = document.getElementById('draw-result');
+  el.className = 'draw-result ' + cls;
+  el.innerHTML = html;
+  el.classList.remove('hidden');
+}
+
+function showNormalState() {
+  document.getElementById('round-normal-row').classList.remove('hidden');
+  document.getElementById('round-stats-row').classList.remove('hidden');
+  document.getElementById('draw-state').classList.remove('active');
+  document.getElementById('draw-result').classList.add('hidden');
+}
+
 async function refreshRound() {
   try {
     const data = await call('GET', '/rounds/current');
@@ -365,7 +418,48 @@ async function refreshRound() {
     document.getElementById('round-jackpot').textContent = data.jackpot_sats / SATS_PER_PLM;
     roundCloseAt = data.closes_at ? new Date(data.closes_at) : null;
     updateRoundTimer();
-  } catch (e) {}
+
+    const isDrawing = data.round_id && DRAWING_STATUSES.includes(data.status);
+
+    if (isDrawing) {
+      if (!(data.round_id in drawStartedAt)) drawStartedAt[data.round_id] = Date.now();
+      const elapsedMs = Date.now() - drawStartedAt[data.round_id];
+      const minMs = data.draw_animation_seconds * 1000;
+
+      if (data.winner_user_id != null && elapsedMs >= minMs && !revealedRounds.has(data.round_id)) {
+        revealedRounds.add(data.round_id);
+        activeResultRoundId = data.round_id;
+        if (myUserId != null && data.winner_user_id === myUserId) {
+          const won = (data.winner_amount_sats / SATS_PER_PLM);
+          showResultState('🎉 Hai vinto! +' + won + ' PLM', 'win');
+          toast('Hai vinto il round #' + data.round_id + '! +' + won + ' PLM', 'success');
+        } else {
+          showResultState('Non hai vinto questa volta.', 'lose');
+        }
+      } else if (!revealedRounds.has(data.round_id)) {
+        showDrawingState();
+      }
+    } else if (data.round_id && data.round_id !== activeResultRoundId) {
+      // a genuinely new round is open — clear any previous result and go back to normal
+      activeResultRoundId = null;
+      showNormalState();
+    } else if (!data.round_id && activeResultRoundId == null) {
+      // nothing has ever been revealed and there's no active round — plain empty state
+      showNormalState();
+    }
+    // else: no active round right now, but we just revealed a result for the last
+    // one — keep it on screen through the cooldown gap instead of flashing back to
+    // "Nessun round attivo".
+
+    scheduleNextRoundPoll(isDrawing);
+  } catch (e) {
+    scheduleNextRoundPoll(false);
+  }
+}
+
+function scheduleNextRoundPoll(fast) {
+  clearTimeout(roundPollTimeout);
+  roundPollTimeout = setTimeout(refreshRound, fast ? 3000 : 15000);
 }
 
 function showDashboard() {
@@ -377,9 +471,7 @@ function showDashboard() {
   refreshMe();
   refreshRound();
   clearInterval(roundTimerInterval);
-  clearInterval(roundPollInterval);
   roundTimerInterval = setInterval(updateRoundTimer, 1000);
-  roundPollInterval = setInterval(refreshRound, 15000);
 }
 
 function persistSession(data, u) {
@@ -429,8 +521,12 @@ async function login() {
 function logout() {
   localStorage.clear();
   token = username = address = null;
+  myUserId = null;
+  activeResultRoundId = null;
+  revealedRounds.clear();
+  for (const key of Object.keys(drawStartedAt)) delete drawStartedAt[key];
   clearInterval(roundTimerInterval);
-  clearInterval(roundPollInterval);
+  clearTimeout(roundPollTimeout);
   document.getElementById('dashboard-section').classList.add('hidden');
   document.getElementById('auth-section').classList.remove('hidden');
 }
@@ -444,11 +540,14 @@ async function copyAddress() {
   }
 }
 
+let myUserId = null;
+
 async function refreshMe() {
   const btn = document.getElementById('refresh-btn');
   await withLoading(btn, '…', async () => {
     try {
       const data = await call('GET', '/users/me');
+      myUserId = data.id;
       document.getElementById('dash-balance').textContent = data.balance_sats / SATS_PER_PLM;
     } catch (e) {
       toast(e.message, 'error');