diff --git a/src/app/layout.ts b/src/app/layout.ts
index 21cb5a7..4c92d9d 100644
--- a/src/app/layout.ts
+++ b/src/app/layout.ts
@@ -73,7 +73,18 @@ export function createLayout(): {
   nav.className = "side-nav";
   nav.setAttribute("aria-label", "Primary navigation");
   nav.setAttribute("role", "navigation");
-  // Bottom navigation removed — redundant with main-screen buttons.
+  // Persistent navigation: home + the four destinations (contract §7 —
+  // emergency must stay one tap from every screen).
+  const navTargets = [HOME_ROUTE, ...ROUTES];
+  for (const r of navTargets) {
+    const a = document.createElement("a");
+    a.href = r.path;
+    a.className = "side-nav__link";
+    a.setAttribute("data-route", r.path);
+    a.textContent = r.id === "home" ? "Home" : r.label;
+    if (r.id === "emergency") a.classList.add("side-nav__link--emergency");
+    nav.append(a);
+  }
   root.append(nav);
 
   return { root, main, nav, brand, statusChip, skipLink };
diff --git a/tests/setup.ts b/tests/setup.ts
new file mode 100644
index 0000000..1b6a4ae
--- /dev/null
+++ b/tests/setup.ts
@@ -0,0 +1,35 @@
+/**
+ * Vitest setup — runs before every test file.
+ *
+ * Why: on Node >=22.4 the experimental native `localStorage` global shadows
+ * jsdom's implementation and is `undefined` unless `--localstorage-file` is
+ * passed, so jsdom-environment tests see `localStorage === undefined`
+ * (ExperimentalWarning at runtime). Install a minimal in-memory stand-in
+ * whenever the global is missing.
+ */
+class MemoryStorage implements Storage {
+  private map = new Map<string, string>();
+  get length(): number {
+    return this.map.size;
+  }
+  clear(): void {
+    this.map.clear();
+  }
+  getItem(key: string): string | null {
+    return this.map.has(key) ? (this.map.get(key) as string) : null;
+  }
+  key(index: number): string | null {
+    return [...this.map.keys()][index] ?? null;
+  }
+  removeItem(key: string): void {
+    this.map.delete(key);
+  }
+  setItem(key: string, value: string): void {
+    this.map.set(key, String(value));
+  }
+}
+
+const g = globalThis as unknown as { localStorage?: Storage };
+if (typeof g.localStorage === "undefined") {
+  g.localStorage = new MemoryStorage();
+}
diff --git a/vitest.config.ts b/vitest.config.ts
index 8cdd72f..5765f26 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -5,6 +5,7 @@ export default defineConfig({
     globals: false,
     include: ["tests/**/*.test.ts"],
     environment: "node",
+    setupFiles: ["./tests/setup.ts"],
     reporters: ["verbose"],
     coverage: {
       enabled: false,