diff --git a/apps/web/app/(app)/(org)/layout.tsx b/apps/web/app/(app)/(org)/layout.tsx
index 8a29d680..833ff366 100644
--- a/apps/web/app/(app)/(org)/layout.tsx
+++ b/apps/web/app/(app)/(org)/layout.tsx
@@ -1,4 +1,5 @@
 import { MobileNav, Sidebar } from "@/components/shell/nav";
+import { SkipLink } from "@/components/shell/skip-link";
 import { Topbar } from "@/components/shell/topbar";
 import { api } from "@/lib/api";
 
@@ -8,11 +9,14 @@ export default async function OrgLayout({ children }: { children: React.ReactNod
 
   return (
     <div className="flex min-h-dvh">
+      <SkipLink />
       <Sidebar />
       <div className="min-w-0 flex-1">
         <MobileNav />
         {me.ok ? <Topbar me={me.data} projects={projectList} /> : null}
-        <main className="px-5 py-8 sm:px-8 lg:px-10">{children}</main>
+        <main id="main-content" tabIndex={-1} className="px-5 py-8 sm:px-8 lg:px-10">
+          {children}
+        </main>
       </div>
     </div>
   );
diff --git a/apps/web/app/(app)/projects/[projectId]/layout.tsx b/apps/web/app/(app)/projects/[projectId]/layout.tsx
index f57bed47..bdbdccf0 100644
--- a/apps/web/app/(app)/projects/[projectId]/layout.tsx
+++ b/apps/web/app/(app)/projects/[projectId]/layout.tsx
@@ -2,6 +2,7 @@ import { notFound } from "next/navigation";
 import { ErrorNotice, Offline } from "@/components/offline";
 import { MobileNav, Sidebar } from "@/components/shell/nav";
 import { RememberProject } from "@/components/shell/remember-project";
+import { SkipLink } from "@/components/shell/skip-link";
 import { Topbar } from "@/components/shell/topbar";
 import { api } from "@/lib/api";
 
@@ -44,11 +45,14 @@ export default async function ProjectLayout({
     // App shell: the viewport is the frame; only the work area (main) scrolls,
     // so full-height tabs like Product can fill it edge to edge.
     <div className="flex h-dvh">
+      <SkipLink />
       <Sidebar project={navProject} />
       <div className="flex min-w-0 flex-1 flex-col">
         <MobileNav project={navProject} />
         {me.ok ? <Topbar me={me.data} projects={projectList} current={p} /> : null}
-        <main className="app-main min-h-0 flex-1 overflow-y-auto">{children}</main>
+        <main id="main-content" tabIndex={-1} className="app-main min-h-0 flex-1 overflow-y-auto">
+          {children}
+        </main>
       </div>
       <RememberProject projectId={p.id} />
     </div>
diff --git a/apps/web/app/login/page.tsx b/apps/web/app/login/page.tsx
index c0971d59..8709deba 100644
--- a/apps/web/app/login/page.tsx
+++ b/apps/web/app/login/page.tsx
@@ -1,13 +1,16 @@
 import { ButtonLink } from "@facility/ui";
+import type { Metadata } from "next";
+
+export const metadata: Metadata = { title: "Sign in" };
 
 export default function LoginPage() {
   const localDevelopment = process.env.NODE_ENV !== "production";
   return (
-    <div className="mx-auto flex min-h-dvh w-full max-w-sm flex-col justify-center gap-10 px-6">
+    <main className="mx-auto flex min-h-dvh w-full max-w-sm flex-col justify-center gap-10 px-6">
       <div className="flex flex-col gap-3">
-        <span className="font-mono text-[22px] font-semibold tracking-tight">
+        <h1 className="font-mono text-[22px] font-semibold tracking-tight">
           facility<span className="text-(--accent)">.</span>
-        </span>
+        </h1>
         <p className="text-sm leading-relaxed text-(--mut)">
           One persistent workspace and shared agent conversation for every story.
         </p>
@@ -29,6 +32,6 @@ export default function LoginPage() {
           The Agile Monkeys
         </a>
       </p>
-    </div>
+    </main>
   );
 }
diff --git a/apps/web/components/shell/skip-link.tsx b/apps/web/components/shell/skip-link.tsx
new file mode 100644
index 00000000..155b4c67
--- /dev/null
+++ b/apps/web/components/shell/skip-link.tsx
@@ -0,0 +1,15 @@
+/**
+ * First focusable element of both authenticated shells: bypasses the sidebar
+ * and topbar for keyboard users (WCAG 2.4.1). Visually hidden until focused,
+ * then fixed top-left so it stays visible over every shell variant.
+ */
+export function SkipLink() {
+  return (
+    <a
+      href="#main-content"
+      className="sr-only focus:not-sr-only focus:fixed focus:top-3 focus:left-3 focus:z-50 rounded-[4px] border border-(--line-strong) bg-(--card) px-4 py-2 text-sm font-medium text-(--ink)"
+    >
+      Skip to main content
+    </a>
+  );
+}
diff --git a/apps/web/test/a11y-baseline.test.tsx b/apps/web/test/a11y-baseline.test.tsx
new file mode 100644
index 00000000..d4951874
--- /dev/null
+++ b/apps/web/test/a11y-baseline.test.tsx
@@ -0,0 +1,94 @@
+import { VisuallyHidden } from "@facility/ui";
+import type { ReactElement } from "react";
+import { renderToString } from "react-dom/server";
+import { describe, expect, it, vi } from "vitest";
+import OrgLayout from "@/app/(app)/(org)/layout";
+import ProjectLayout from "@/app/(app)/projects/[projectId]/layout";
+import LoginPage, { metadata as loginMetadata } from "@/app/login/page";
+import { SkipLink } from "@/components/shell/skip-link";
+
+vi.mock("next/navigation", () => ({
+  notFound: () => {
+    throw new Error("notFound");
+  },
+  redirect: () => {
+    throw new Error("redirect");
+  },
+  usePathname: () => "/",
+}));
+vi.mock("next/link", () => ({
+  default: ({ href, children }: { href: string; children: React.ReactNode }) => (
+    <a href={href}>{children}</a>
+  ),
+}));
+vi.mock("@/lib/api", () => ({
+  api: {
+    me: async () => ({ ok: true, data: {} }),
+    projects: async () => ({ ok: true, data: [] }),
+    project: async () => ({ ok: true, data: { id: "p_1", slug: "acme", name: "Acme" } }),
+  },
+}));
+vi.mock("@/components/shell/topbar", () => ({ Topbar: () => null }));
+vi.mock("@/components/shell/remember-project", () => ({ RememberProject: () => null }));
+
+function render(element: ReactElement) {
+  return renderToString(element);
+}
+
+describe("skip link", () => {
+  it("targets the main content and is keyboard-only visible", () => {
+    const html = render(<SkipLink />);
+    expect(html).toContain('href="#main-content"');
+    expect(html).toContain("Skip to main content");
+    expect(html).toContain("sr-only");
+    expect(html).toContain("focus:not-sr-only");
+  });
+
+  it("precedes the sidebar and lands on a focusable main in the org shell", async () => {
+    const html = render(await OrgLayout({ children: <p>dashboard</p> }));
+    const skip = html.indexOf("Skip to main content");
+    const sidebar = html.indexOf('aria-label="Primary"');
+    expect(skip).toBeGreaterThanOrEqual(0);
+    expect(skip).toBeLessThan(sidebar);
+    expect(html).toContain('id="main-content"');
+    expect(html).toContain('tabindex="-1"');
+  });
+
+  it("holds for the project shell too", async () => {
+    const html = render(
+      await ProjectLayout({
+        children: <p>overview</p>,
+        params: Promise.resolve({ projectId: "p_1" }),
+      }),
+    );
+    const skip = html.indexOf("Skip to main content");
+    const sidebar = html.indexOf('aria-label="Primary"');
+    expect(skip).toBeGreaterThanOrEqual(0);
+    expect(skip).toBeLessThan(sidebar);
+    expect(html).toContain('id="main-content"');
+    expect(html).toContain('tabindex="-1"');
+  });
+});
+
+describe("visually hidden text", () => {
+  it("names icon-only controls without removing content from the tree", () => {
+    const html = render(
+      <button type="button">
+        <svg aria-hidden viewBox="0 0 16 16" />
+        <VisuallyHidden>Delete story</VisuallyHidden>
+      </button>,
+    );
+    expect(html).toContain("Delete story");
+    expect(html).toContain("sr-only");
+    expect(html).not.toContain("display:none");
+  });
+});
+
+describe("login page landmarks", () => {
+  it("exposes a main landmark, a heading, and a descriptive title", () => {
+    const html = render(<LoginPage />);
+    expect(html).toContain("<main");
+    expect(html).toContain("<h1");
+    expect(loginMetadata.title).toBe("Sign in");
+  });
+});
diff --git a/packages/ui/src/index.ts b/packages/ui/src/index.ts
index ad740f9d..16409a53 100644
--- a/packages/ui/src/index.ts
+++ b/packages/ui/src/index.ts
@@ -13,6 +13,7 @@ export {
   PillTag,
   StatusDot,
   toneFor,
+  VisuallyHidden,
 } from "./primitives";
 export type { TerminalLine } from "./terminal";
 export { Terminal } from "./terminal";
diff --git a/packages/ui/src/primitives.tsx b/packages/ui/src/primitives.tsx
index 8808c301..16686e17 100644
--- a/packages/ui/src/primitives.tsx
+++ b/packages/ui/src/primitives.tsx
@@ -109,6 +109,11 @@ export function toneFor(status: string): Semantic {
   }
 }
 
+/** Text for assistive tech only: visually removed, never `display: none`. */
+export function VisuallyHidden({ className, ...props }: HTMLAttributes<HTMLSpanElement>) {
+  return <span className={cx("sr-only", className)} {...props} />;
+}
+
 /** Section separator — hairline, generous air. */
 export function Divider({ className }: { className?: string }) {
   return <div className={cx("border-t border-(--line)", className)} />;