diff --git a/apps/web/src/components/AttackDemo.tsx b/apps/web/src/components/AttackDemo.tsx
index 6c9d189..719ac5b 100644
--- a/apps/web/src/components/AttackDemo.tsx
+++ b/apps/web/src/components/AttackDemo.tsx
@@ -5,11 +5,12 @@ import type { AttackStep } from "../lib/demoTypes";
 import { useToast } from "../ui/Toast";
 
 export function StepList({ steps, variant }: { steps: AttackStep[]; variant: "bad" | "good" }) {
+  const listLabel = variant === "bad" ? "Seal-off attack steps" : "Seal-on protection steps";
   return (
-    <ul className={`attack-steps ${variant}`}>
+    <ul className={`attack-steps ${variant}`} aria-label={listLabel}>
       {steps.map((s) => (
         <li key={s.label} className={s.ok ? "ok" : "fail"}>
-          <span className="attack-mark">{s.ok ? "✓" : "✗"}</span>
+          <span className="attack-mark" aria-hidden="true">{s.ok ? "✓" : "✗"}</span>
           <div>
             <strong>{s.label}</strong>
             <p>{s.detail}</p>
@@ -81,7 +82,7 @@ export function AttackDemo({ phase = "Reveal" }: { phase?: "Open" | "Reveal" | "
   const revealOpen = phase !== "Open";
 
   return (
-    <section className="panel attack-panel">
+    <section className="panel attack-panel" aria-label="Seal-off vs seal-on attack">
       <header className="panel-head attack-head">
         <div>
           <p className="eyebrow">Main stage</p>
@@ -94,24 +95,30 @@ export function AttackDemo({ phase = "Reveal" }: { phase?: "Open" | "Reveal" | "
       </header>
 
       <div className="attack-control">
-        <button type="button" className="btn primary" onClick={run} disabled={loading}>
+        <button
+          type="button"
+          className="btn primary"
+          onClick={run}
+          disabled={loading}
+          aria-busy={loading}
+        >
           {loading ? "Running live tlock demo..." : "Run live attack comparison"}
         </button>
         {round != null && (
           <p className="muted">Sealed to future Drand round R={round.toLocaleString()}</p>
         )}
-        {err && <p className="error">{err}</p>}
+        {err && <p className="error" role="alert">{err}</p>}
       </div>
 
       <div className="attack-columns">
-        <div className="attack-col bad">
+        <div className="attack-col bad" role="region" aria-label="Seal OFF — broken commit-reveal">
           <h3>Seal OFF — broken commit-reveal</h3>
           <p className="attack-sub">
             Bid stored in reversible form. Observer reads early. Losing bidder can abort.
           </p>
           <SealOffColumn steps={sealOff} revealOpen={revealOpen} />
         </div>
-        <div className="attack-col good">
+        <div className="attack-col good" role="region" aria-label="Seal ON — Sub Rosa + Drand tlock">
           <h3>Seal ON — Sub Rosa + Drand tlock</h3>
           <p className="attack-sub">
             Undecryptable until R. Permissionless mass reveal. Commitment binding on-chain.
diff --git a/apps/web/src/components/RoundStatusBadge.tsx b/apps/web/src/components/RoundStatusBadge.tsx
index aaf3f81..244bc30 100644
--- a/apps/web/src/components/RoundStatusBadge.tsx
+++ b/apps/web/src/components/RoundStatusBadge.tsx
@@ -25,7 +25,12 @@ export function RoundStatusBadge({
   onRetry,
 }: RoundStatusBadgeProps) {
   return (
-    <span className={`round-status-badge ${state}`} title={error ?? message ?? undefined}>
+    <span
+      className={`round-status-badge ${state}`}
+      role={state === "error" ? "alert" : "status"}
+      aria-busy={state === "loading"}
+      title={error ?? message ?? undefined}
+    >
       {state === "loading" ? (
         <span className="round-status-spinner" aria-hidden="true" />
       ) : null}
diff --git a/apps/web/src/demo/demo-a11y-smoke.test.tsx b/apps/web/src/demo/demo-a11y-smoke.test.tsx
new file mode 100644
index 0000000..2d39caa
--- /dev/null
+++ b/apps/web/src/demo/demo-a11y-smoke.test.tsx
@@ -0,0 +1,111 @@
+// Copyright (c) 2026 Sub Rosa contributors
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { dirname, resolve } from "node:path";
+import test from "node:test";
+import { fileURLToPath } from "node:url";
+import { renderToStaticMarkup } from "react-dom/server";
+import { createFakeTime } from "@sub-rosa/time";
+
+import { AttackDemo, SealOffColumn, StepList } from "../components/AttackDemo";
+import { RoundStatusBadge } from "../components/RoundStatusBadge";
+import type { AttackStep } from "../lib/demoTypes";
+import { TimeProvider } from "../lib/time";
+import { ToastProvider } from "../ui/Toast";
+
+const DEMO_DIR = dirname(fileURLToPath(import.meta.url));
+
+function readWebSource(relPath: string): string {
+  return readFileSync(resolve(DEMO_DIR, "..", relPath), "utf8");
+}
+
+const SAMPLE_STEPS: AttackStep[] = [
+  { label: "Bidder A commits", detail: "Commitment hash H recorded on-chain", ok: true },
+  { label: "Observer inspects before R", detail: "Plaintext bid leaked early", ok: false },
+];
+
+test("demo default state exposes landmarks, region roles, headings, and focusable controls", () => {
+  const html = renderToStaticMarkup(
+    <TimeProvider value={createFakeTime(1_700_000_000_000)}>
+      <ToastProvider>
+        <RoundStatusBadge state="empty" message="Create or join a round" />
+        <AttackDemo phase="Reveal" />
+      </ToastProvider>
+    </TimeProvider>,
+  );
+
+  assert.match(html, /role="status"[^>]*aria-busy="false"[^>]*>.*<span class="round-status-label">Empty<\/span>/);
+  assert.match(html, /<section class="panel attack-panel" aria-label="Seal-off vs seal-on attack">/);
+  assert.match(html, /<h2>Seal-off vs seal-on attack<\/h2>/);
+  assert.match(html, /<div class="attack-col bad" role="region" aria-label="Seal OFF — broken commit-reveal">/);
+  assert.match(html, /<div class="attack-col good" role="region" aria-label="Seal ON — Sub Rosa \+ Drand tlock">/);
+  assert.match(
+    html,
+    /<button type="button" class="btn primary" aria-busy="false">Run live attack comparison<\/button>/,
+  );
+});
+
+test("demo loading state sets aria-busy, status role, and decorative spinner attributes", () => {
+  const html = renderToStaticMarkup(
+    <RoundStatusBadge state="loading" message="Fetching round state" />,
+  );
+
+  assert.match(html, /role="status"/);
+  assert.match(html, /aria-busy="true"/);
+  assert.match(html, /<span class="round-status-spinner" aria-hidden="true"><\/span>/);
+  assert.match(html, /<span class="round-status-label">Loading<\/span>/);
+});
+
+test("demo error state exposes alert role, error copy, and focusable retry control", () => {
+  const html = renderToStaticMarkup(
+    <RoundStatusBadge
+      state="error"
+      error="RPC connection timed out"
+      onRetry={() => {}}
+    />,
+  );
+
+  assert.match(html, /role="alert"/);
+  assert.match(html, /<span class="round-status-icon" aria-hidden="true">!<\/span>/);
+  assert.match(html, /<span class="round-status-label">Error<\/span>/);
+  assert.match(html, /<span class="round-status-err">RPC connection timed out<\/span>/);
+  assert.match(html, /<button type="button" class="round-status-retry">Retry<\/button>/);
+});
+
+test("demo seal-on state exposes named list and hides decorative status marks from assistive tech", () => {
+  const html = renderToStaticMarkup(
+    <StepList steps={SAMPLE_STEPS} variant="good" />,
+  );
+
+  assert.match(html, /<ul class="attack-steps good" aria-label="Seal-on protection steps">/);
+  assert.match(html, /<span class="attack-mark" aria-hidden="true">✓<\/span>/);
+  assert.match(html, /<strong>Bidder A commits<\/strong>/);
+});
+
+test("demo seal-off state withholds values while round is Open and exposes named list once Reveal opens", () => {
+  const closedHtml = renderToStaticMarkup(
+    <SealOffColumn steps={SAMPLE_STEPS} revealOpen={false} />,
+  );
+  assert.match(closedHtml, /Bids still sealed — values hidden until Drand R opens the reveal round\./);
+  assert.doesNotMatch(closedHtml, /Plaintext bid leaked early/);
+
+  const openHtml = renderToStaticMarkup(
+    <SealOffColumn steps={SAMPLE_STEPS} revealOpen={true} />,
+  );
+  assert.match(openHtml, /<ul class="attack-steps bad" aria-label="Seal-off attack steps">/);
+  assert.match(openHtml, /<span class="attack-mark" aria-hidden="true">✗<\/span>/);
+  assert.match(openHtml, /Plaintext bid leaked early/);
+});
+
+test("DemoPage source defines navigation landmark, tablist roles, error alert, and sealed vs leaky list labels", () => {
+  const demoPageSource = readWebSource("pages/DemoPage.tsx");
+
+  assert.match(demoPageSource, /<aside className="case-nav" aria-label="Demo navigation">/);
+  assert.match(demoPageSource, /<div className="mode-switch" role="tablist" aria-label="Demo mode">/);
+  assert.match(demoPageSource, /role="tab"/);
+  assert.match(demoPageSource, /aria-selected=\{mode === "live"\}/);
+  assert.match(demoPageSource, /aria-selected=\{mode === "evidence"\}/);
+  assert.match(demoPageSource, /<ul className="example-list" aria-label="Visible to everyone">/);
+  assert.match(demoPageSource, /<ul className="example-list sealed" aria-label="Sealed until reveal">/);
+  assert.match(demoPageSource, /className="evidence-intro evidence-intro--error" role="alert"/);
+});
diff --git a/apps/web/src/demo/trace-health-check.test.ts b/apps/web/src/demo/trace-health-check.test.ts
index 403de6b..a699836 100644
--- a/apps/web/src/demo/trace-health-check.test.ts
+++ b/apps/web/src/demo/trace-health-check.test.ts
@@ -121,3 +121,6 @@ test("health check rejects a demo trace containing an injected secret seed", ()
   );
 });
 
+import "./demo-a11y-smoke.test";
+
+
diff --git a/apps/web/src/pages/DemoPage.tsx b/apps/web/src/pages/DemoPage.tsx
index 2fc05ea..becab2f 100644
--- a/apps/web/src/pages/DemoPage.tsx
+++ b/apps/web/src/pages/DemoPage.tsx
@@ -854,13 +854,13 @@ export function DemoPage({
     <main className="app-page">
       <ConfettiBurst fire={confettiTick} />
       <section className="app-shell">
-        <aside className="case-nav">
+        <aside className="case-nav" aria-label="Demo navigation">
           <button type="button" className="brand-link" onClick={goHome}>
             <img src={LOGO_SRC} alt="" />
             <span>Sub Rosa</span>
           </button>
 
-          <div className="mode-switch" role="tablist">
+          <div className="mode-switch" role="tablist" aria-label="Demo mode">
             <button
               type="button"
               role="tab"
diff --git a/docs/DEMO_SCRIPT.md b/docs/DEMO_SCRIPT.md
index 21a1242..5aabd8c 100644
--- a/docs/DEMO_SCRIPT.md
+++ b/docs/DEMO_SCRIPT.md
@@ -115,6 +115,19 @@ pnpm mainnet:verify
 pnpm keeper:watch
 ```
 
+## Accessibility Smoke Checks
+
+`apps/web/src/demo/demo-a11y-smoke.test.tsx` verifies accessible names, roles,
+landmarks, and focusable controls across the demo page's default, loading
+(`aria-busy="true"` / `role="status"`), error (`role="alert"` + retry button),
+seal-on (`aria-label="Seal-on protection steps"` / `aria-label="Sealed until reveal"`),
+and seal-off (`aria-label="Seal-off attack steps"` / withheld pre-reveal copy)
+states:
+
+```bash
+pnpm --filter @sub-rosa/web exec node --import tsx --test src/demo/demo-a11y-smoke.test.tsx
+```
+
 ## Docs For Reviewers
 
 - [FUNDING_STRATEGY.md](./FUNDING_STRATEGY.md)