feat: reuse tabs across multi-run — no more tab bloat

- tabRegistry preserved across resetState (like seenCodes/accounts)
- New reuseOrCreateTab() helper: navigates existing tab or creates new one
- All steps use reuseOrCreateTab: VPS panel, auth page, mail
- Mail tabs: only activate if alive, don't re-navigate (preserves session)
- Auth tab: reused between step 2→6→8, navigated to new URLs
- VPS tab: reused across runs, re-injected on navigation

sidepanel/sidepanel.css

@@ -541,6 +541,94 @@ header {
 
 .log-line { animation: fadeIn 120ms ease-out; }
 
+/* ============================================================
+   Toast Notifications
+   ============================================================ */
+
+#toast-container {
+  position: fixed;
+  top: 12px;
+  left: 12px;
+  right: 12px;
+  z-index: 1000;
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+  pointer-events: none;
+}
+
+.toast {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 10px 12px;
+  border-radius: var(--radius-md);
+  font-size: 12px;
+  font-weight: 500;
+  box-shadow: var(--shadow-md), 0 4px 12px rgba(0,0,0,0.1);
+  pointer-events: auto;
+  animation: toastIn 250ms ease-out;
+  border: 1px solid;
+}
+
+.toast.toast-exit {
+  animation: toastOut 200ms ease-in forwards;
+}
+
+.toast-error {
+  background: var(--red-soft);
+  border-color: var(--red);
+  color: var(--red);
+}
+
+.toast-warn {
+  background: var(--orange-soft);
+  border-color: var(--orange);
+  color: var(--orange);
+}
+
+.toast-success {
+  background: var(--green-soft);
+  border-color: var(--green);
+  color: var(--green);
+}
+
+.toast-info {
+  background: var(--blue-soft);
+  border-color: var(--blue);
+  color: var(--blue);
+}
+
+.toast svg {
+  flex-shrink: 0;
+}
+
+.toast-msg {
+  flex: 1;
+}
+
+.toast-close {
+  background: none;
+  border: none;
+  color: inherit;
+  opacity: 0.6;
+  cursor: pointer;
+  padding: 2px;
+  font-size: 16px;
+  line-height: 1;
+}
+.toast-close:hover { opacity: 1; }
+
+@keyframes toastIn {
+  from { opacity: 0; transform: translateY(-10px) scale(0.96); }
+  to { opacity: 1; transform: translateY(0) scale(1); }
+}
+
+@keyframes toastOut {
+  from { opacity: 1; transform: translateY(0) scale(1); }
+  to { opacity: 0; transform: translateY(-10px) scale(0.96); }
+}
+
 @media (prefers-reduced-motion: reduce) {
   *, *::before, *::after {
     animation-duration: 0.01ms !important;

sidepanel/sidepanel.html

@@ -140,6 +140,7 @@
     <div id="log-area"></div>
   </section>
 
+  <div id="toast-container"></div>
   <script src="sidepanel.js"></script>
 </body>
 </html>

sidepanel/sidepanel.js

@@ -23,6 +23,38 @@ const inputVpsUrl = document.getElementById('input-vps-url');
 const selectMailProvider = document.getElementById('select-mail-provider');
 const inputRunCount = document.getElementById('input-run-count');
 
+// ============================================================
+// Toast Notifications
+// ============================================================
+
+const toastContainer = document.getElementById('toast-container');
+
+const TOAST_ICONS = {
+  error: '<svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="10"/><line x1="15" y1="9" x2="9" y2="15"/><line x1="9" y1="9" x2="15" y2="15"/></svg>',
+  warn: '<svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10.29 3.86L1.82 18a2 2 0 0 0 1.71 3h16.94a2 2 0 0 0 1.71-3L13.71 3.86a2 2 0 0 0-3.42 0z"/><line x1="12" y1="9" x2="12" y2="13"/><line x1="12" y1="17" x2="12.01" y2="17"/></svg>',
+  success: '<svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M22 11.08V12a10 10 0 1 1-5.93-9.14"/><polyline points="22 4 12 14.01 9 11.01"/></svg>',
+  info: '<svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="10"/><line x1="12" y1="16" x2="12" y2="12"/><line x1="12" y1="8" x2="12.01" y2="8"/></svg>',
+};
+
+function showToast(message, type = 'error', duration = 4000) {
+  const toast = document.createElement('div');
+  toast.className = `toast toast-${type}`;
+  toast.innerHTML = `${TOAST_ICONS[type] || ''}<span class="toast-msg">${escapeHtml(message)}</span><button class="toast-close">&times;</button>`;
+
+  toast.querySelector('.toast-close').addEventListener('click', () => dismissToast(toast));
+  toastContainer.appendChild(toast);
+
+  if (duration > 0) {
+    setTimeout(() => dismissToast(toast), duration);
+  }
+}
+
+function dismissToast(toast) {
+  if (!toast.parentNode) return;
+  toast.classList.add('toast-exit');
+  toast.addEventListener('animationend', () => toast.remove());
+}
+
 // ============================================================
 // State Restore on load
 // ============================================================
@@ -193,7 +225,7 @@ document.querySelectorAll('.step-btn').forEach(btn => {
     if (step === 3) {
       const email = inputEmail.value.trim();
       if (!email) {
-        appendLog({ message: 'Please paste email address first', level: 'error', timestamp: Date.now() });
+        showToast('Please paste email address first', 'warn');
         return;
       }
       await chrome.runtime.sendMessage({ type: 'EXECUTE_STEP', source: 'sidepanel', payload: { step, email } });
@@ -215,7 +247,7 @@ btnAutoRun.addEventListener('click', async () => {
 btnAutoContinue.addEventListener('click', async () => {
   const email = inputEmail.value.trim();
   if (!email) {
-    appendLog({ message: 'Please paste DuckDuckGo email first!', level: 'error', timestamp: Date.now() });
+    showToast('Please paste DuckDuckGo email first!', 'warn');
     return;
   }
   autoContinueBar.style.display = 'none';
@@ -279,6 +311,9 @@ chrome.runtime.onMessage.addListener((message) => {
   switch (message.type) {
     case 'LOG_ENTRY':
       appendLog(message.payload);
+      if (message.payload.level === 'error') {
+        showToast(message.payload.message, 'error');
+      }
       break;
 
     case 'STEP_STATUS_CHANGED': {