diff --git a/public/warmup-banner.js b/public/warmup-banner.js
index 0a1b962f..f48143d5 100644
--- a/public/warmup-banner.js
+++ b/public/warmup-banner.js
@@ -54,6 +54,29 @@
         ' / ' + fmtNum(total) + ' (' + pct + '%)');
     }
 
+    // Async migrations (#1724): per-migration progress + failed-state surface.
+    // Banner stays up while any migration is "running" — gated by isSteadyState
+    // checking async_migrations_running. Failed migrations are surfaced
+    // explicitly with their error message; we do NOT silently drop them.
+    var migrations = Array.isArray(h.async_migrations) ? h.async_migrations : [];
+    for (var mi = 0; mi < migrations.length; mi++) {
+      var m = migrations[mi] || {};
+      var mname = String(m.name || 'migration');
+      if (m.status === 'running') {
+        var mp = Number(m.rowsProcessed) || 0;
+        var mt = Number(m.rowsTotal) || 0;
+        var line = 'Migration ' + mname + ': ' + fmtNum(mp) + ' / ' + fmtNum(mt) + ' rows';
+        var eta = Number(m.etaSec);
+        if (isFinite(eta) && eta > 0) {
+          line += ' (ETA ' + Math.round(eta) + 's)';
+        }
+        msgs.push(line);
+      } else if (m.status === 'failed') {
+        var err = m.errorMessage ? String(m.errorMessage) : 'unknown error';
+        msgs.push('Migration ' + mname + ' FAILED: ' + err);
+      }
+    }
+
     var liveness = h.ingest_liveness || {};
     var srcs = Object.keys(liveness).sort();
     for (var i = 0; i < srcs.length; i++) {
@@ -76,7 +99,9 @@
   }
 
   /**
-   * Steady-state predicate: ready=true AND from_pubkey_backfill.done=true.
+   * Steady-state predicate: ready=true AND from_pubkey_backfill.done=true
+   * AND no async migration is currently running (#1724) AND no async migration
+   * is in a "failed" state (failures must remain visible until ack'd).
    * Once true, banner is dismissed and polling is torn down.
    */
   function isSteadyState(healthz) {
@@ -84,6 +109,11 @@
     if (healthz.ready !== true) return false;
     var bf = healthz.from_pubkey_backfill;
     if (bf && bf.done === false) return false;
+    if (healthz.async_migrations_running === true) return false;
+    var migs = Array.isArray(healthz.async_migrations) ? healthz.async_migrations : [];
+    for (var i = 0; i < migs.length; i++) {
+      if (migs[i] && migs[i].status === 'failed') return false;
+    }
     return true;
   }
 
diff --git a/test-warmup-banner-migrations.js b/test-warmup-banner-migrations.js
new file mode 100644
index 00000000..cb6606bc
--- /dev/null
+++ b/test-warmup-banner-migrations.js
@@ -0,0 +1,125 @@
+/* Unit tests for warmup-banner.js async-migration surface (#1724).
+ *
+ * Pins:
+ *   - Banner stays visible while /api/healthz.async_migrations_running=true,
+ *     even if ready=true and pubkey backfill is done.
+ *   - Per-migration progress line renders name + rows_processed/rows_total + ETA.
+ *   - "failed" status surfaces an explicit error message; isSteadyState=false.
+ *   - When migrations finish (none running, none failed), banner returns to
+ *     steady state.
+ *
+ * Matches the vm-sandbox / no-Playwright pattern used by test-warmup-banner.js.
+ */
+'use strict';
+const vm = require('vm');
+const fs = require('fs');
+const path = require('path');
+const assert = require('assert');
+
+let passed = 0, failed = 0;
+async function test(name, fn) {
+  try {
+    await fn();
+    passed++;
+    console.log('  \u2705 ' + name);
+  } catch (e) {
+    failed++;
+    console.log('  \u274C ' + name + ': ' + e.message);
+  }
+}
+
+function loadPureModule() {
+  const ctx = { window: {}, module: { exports: {} }, console, Date };
+  vm.createContext(ctx);
+  const src = fs.readFileSync(path.join(__dirname, 'public', 'warmup-banner.js'), 'utf8');
+  vm.runInContext(src, ctx);
+  return ctx.window.__warmupBanner || ctx.module.exports;
+}
+
+(async function main() {
+  console.log('warmup-banner.js async migrations (#1724):');
+
+  const api = loadPureModule();
+  const NOW = 1_700_000_000_000;
+
+  // Healthz that would otherwise be steady-state.
+  function steadyBase() {
+    return {
+      ready: true,
+      from_pubkey_backfill: { done: true, processed: 1, total: 1 },
+      ingest_liveness: {},
+    };
+  }
+
+  await test('async_migrations_running=true keeps banner up despite ready+backfill done', () => {
+    const h = Object.assign(steadyBase(), {
+      async_migrations_running: true,
+      async_migrations: [
+        { name: 'tx_last_seen_backfill', status: 'running',
+          rowsProcessed: 12000, rowsTotal: 71000, etaSec: 2.4 },
+      ],
+    });
+    assert.strictEqual(api.isSteadyState(h), false,
+      'isSteadyState must be false while a migration is running');
+    assert.strictEqual(api.shouldShowBanner(h, 'ready', NOW), true,
+      'banner must remain visible while migrations run');
+  });
+
+  await test('per-migration progress line shows name + processed/total + ETA', () => {
+    const h = Object.assign(steadyBase(), {
+      async_migrations_running: true,
+      async_migrations: [
+        { name: 'tx_last_seen_backfill', status: 'running',
+          rowsProcessed: 12000, rowsTotal: 71000, etaSec: 2.4 },
+      ],
+    });
+    const msgs = api.getWarmupMessages(h, 'ready', NOW);
+    const line = msgs.find(m => /tx_last_seen_backfill/.test(m));
+    assert.ok(line, 'expected per-migration line; got: ' + JSON.stringify(msgs));
+    assert.ok(/12,000/.test(line) && /71,000/.test(line),
+      'expected formatted rows; got: ' + line);
+    assert.ok(/ETA/.test(line) && /2s/.test(line),
+      'expected ETA seconds; got: ' + line);
+  });
+
+  await test('failed status surfaces error message explicitly (not silently dropped)', () => {
+    const h = Object.assign(steadyBase(), {
+      async_migrations_running: false,
+      async_migrations: [
+        { name: 'tx_last_seen_backfill', status: 'failed',
+          rowsProcessed: 5000, rowsTotal: 71000,
+          errorMessage: 'disk I/O error' },
+      ],
+    });
+    const msgs = api.getWarmupMessages(h, 'ready', NOW);
+    const line = msgs.find(m => /tx_last_seen_backfill/.test(m));
+    assert.ok(line, 'failed migration MUST surface a message; got: ' + JSON.stringify(msgs));
+    assert.ok(/FAIL/i.test(line), 'expected FAIL token; got: ' + line);
+    assert.ok(/disk I\/O error/.test(line), 'expected error message; got: ' + line);
+    assert.strictEqual(api.isSteadyState(h), false,
+      'failed migration must NOT count as steady state');
+  });
+
+  await test('done migrations alone (no running, no failed) → steady state', () => {
+    const h = Object.assign(steadyBase(), {
+      async_migrations_running: false,
+      async_migrations: [
+        { name: 'tx_last_seen_backfill', status: 'done',
+          rowsProcessed: 71000, rowsTotal: 71000 },
+      ],
+    });
+    assert.strictEqual(api.isSteadyState(h), true,
+      'done-only migrations are steady state');
+    assert.strictEqual(api.shouldShowBanner(h, 'ready', NOW), false);
+  });
+
+  await test('no async_migrations field at all → behavior unchanged (back-compat)', () => {
+    const h = steadyBase(); // no async_migrations* fields
+    assert.strictEqual(api.isSteadyState(h), true);
+    assert.strictEqual(api.shouldShowBanner(h, 'ready', NOW), false);
+  });
+
+  console.log('');
+  console.log('passed=' + passed + ' failed=' + failed);
+  process.exit(failed > 0 ? 1 : 0);
+})();