diff --git a/src/popup/popup.css b/src/popup/popup.css
index 583838f..ded12a4 100644
--- a/src/popup/popup.css
+++ b/src/popup/popup.css
@@ -242,6 +242,40 @@ body {
   white-space: nowrap;
 }
 
+/* First-run banner */
+.first-run-banner {
+  display: flex;
+  align-items: flex-start;
+  gap: 10px;
+  padding: 10px 16px;
+  background: #fef2f2;
+  border-bottom: 1px solid #fecaca;
+}
+
+.first-run-icon {
+  width: 22px;
+  height: 22px;
+  border-radius: 50%;
+  background: #dc2626;
+  color: #fff;
+  font-size: 14px;
+  font-weight: 700;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  flex-shrink: 0;
+}
+
+.first-run-text {
+  font-size: 12px;
+  color: #991b1b;
+  line-height: 1.4;
+}
+
+.first-run-text strong {
+  font-weight: 600;
+}
+
 /* Identity tab */
 .id-section {
   margin-bottom: 12px;
diff --git a/src/popup/popup.html b/src/popup/popup.html
index 4412485..bf9204e 100644
--- a/src/popup/popup.html
+++ b/src/popup/popup.html
@@ -35,6 +35,15 @@
       <button class="tab" data-tab="test">Test</button>
     </nav>
 
+    <!-- First-Run Setup Banner -->
+    <div class="first-run-banner" id="firstRunBanner" style="display:none">
+      <div class="first-run-icon">!</div>
+      <div class="first-run-text">
+        <strong>Setup required</strong> — Silent Send needs to know who you are before it can protect you.
+        Fill in at least your name below, then click Save Identity.
+      </div>
+    </div>
+
     <!-- Identity Tab (Smart Patterns) -->
     <section class="tab-content active" id="tab-identity">
       <p class="help-text">Tell Silent Send who you are. It auto-catches all variations.</p>
diff --git a/src/popup/popup.js b/src/popup/popup.js
index 8d3cbb3..0e24c94 100644
--- a/src/popup/popup.js
+++ b/src/popup/popup.js
@@ -23,6 +23,7 @@ document.addEventListener('DOMContentLoaded', async () => {
   renderActivity();
   loadIdentityForm();
   updateStatusDot();
+  checkFirstRun();
 
   $('#enableToggle').checked = settings.enabled;
 
@@ -196,6 +197,7 @@ async function saveIdentity() {
   };
 
   await Storage.saveIdentity(identity);
+  checkFirstRun();
 
   // Flash save button
   const btn = $('#btnSaveIdentity');
@@ -207,6 +209,28 @@ async function saveIdentity() {
   }, 1500);
 }
 
+// --- First-Run Check ---
+function checkFirstRun() {
+  const hasNames = (identity.names || []).length > 0;
+  const hasEmails = (identity.emails || []).length > 0 || !!identity.catchAllEmail;
+  const hasUsernames = (identity.usernames || []).length > 0;
+  const hasMappings = mappings.length > 0;
+
+  // Show banner if nothing is configured at all
+  const isConfigured = hasNames || hasEmails || hasUsernames || hasMappings;
+  const banner = $('#firstRunBanner');
+  banner.style.display = isConfigured ? 'none' : 'flex';
+
+  // Also update the status dot — orange if unconfigured
+  const dot = $('#statusDot');
+  if (!isConfigured && settings.enabled) {
+    dot.classList.add('off-site');
+    dot.classList.remove('disabled');
+  } else {
+    dot.classList.remove('off-site');
+  }
+}
+
 // --- Add Mapping ---
 async function addMapping() {
   const real = $('#inputReal').value.trim();