diff --git a/README.md b/README.md
index 6c73d99..5ed3377 100644
--- a/README.md
+++ b/README.md
@@ -134,8 +134,26 @@ the hooks in `src/lib`.
 ### Route-level boundary (`src/app/error.tsx`)
 
 Catches exceptions thrown inside individual route segments. Renders inside the
-root layout so the Header, Footer, and ToastProvider remain visible. Shows the
-error message and a "Try again" button that calls Next.js's `reset()`.
+root layout so the Header, Footer, and ToastProvider remain visible.
+
+Key features:
+
+- **Accessible error presentation:** Error message wrapped in `role="alert"` so
+  screen readers announce it immediately.
+- **Recovery action:** "Try again" button (using the shared `Button` component)
+  wired to Next.js's `reset()` callback allows users to retry without a full page
+  reload — essential for transient failures like flaky fetches.
+- **Production safety:** Only `error.message` is rendered; stack traces never
+  leak into the DOM.
+- **Debug support:** `error.digest` (if present) is logged to the console for
+  debugging but not prominently displayed to users.
+- **Keyboard accessible:** Button includes `focus-visible` outline and is fully
+  operable via keyboard.
+- **Dark mode compatible:** All styling supports both light and dark themes.
+
+Behaviour is covered by `src/app/error.test.tsx`, which asserts the alert region
+renders, the reset callback is invoked on click, no stack traces appear, and edge
+cases like empty messages are handled gracefully.
 
 ### Global boundary (`src/app/global-error.tsx`)
 
@@ -234,6 +252,10 @@ The following frontend routes are defined under `src/app/`:
 
 The home page (`src/app/page.tsx`) renders the primary navigation entry points (Manage services, View stats, Record usage, Agents, Docs) and the external Stellar link inside a `<nav aria-label="Quick links">` landmark with a semantic `<ul>` / `<li>` list structure. This improves discoverability for screen-reader users.
 
+## 404 page recovery links
+
+The 404 page (`src/app/not-found.tsx`) renders a `<nav aria-label="Helpful links">` landmark below the error message with quick-return links to four primary surfaces (Home, Services, Stats, Docs). This gives users a semantic, keyboard-accessible path back into the app without relying on the browser back button. The navigation uses a `<ul>` / `<li>` list structure and all links include `focus-visible` outlines for keyboard accessibility.
+
 ## Security headers
 
 A baseline security header set (CSP, `X-Frame-Options: DENY`, `Referrer-Policy`, `X-Content-Type-Options`, `Permissions-Policy`, HSTS) is wired up in `next.config.ts` via `src/lib/securityHeaders.ts`. The CSP `connect-src` directive tracks `NEXT_PUBLIC_AGENTPAY_API_BASE` automatically; `<a href>` links to external sites (`https://stellar.org`, etc.) remain navigable.
diff --git a/src/app/error.test.tsx b/src/app/error.test.tsx
new file mode 100644
index 0000000..0fef198
--- /dev/null
+++ b/src/app/error.test.tsx
@@ -0,0 +1,306 @@
+import { render, screen, fireEvent } from "@testing-library/react";
+import ErrorBoundary from "./error";
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+function makeError(
+  message: string,
+  digest?: string
+): Error & { digest?: string } {
+  const err = new Error(message) as Error & { digest?: string };
+  if (digest !== undefined) err.digest = digest;
+  return err;
+}
+
+// Silence console.error noise produced by the useEffect log inside the
+// component so Jest output stays clean.
+beforeEach(() => {
+  jest.spyOn(console, "error").mockImplementation(() => {});
+});
+
+afterEach(() => {
+  jest.restoreAllMocks();
+});
+
+// ---------------------------------------------------------------------------
+// Rendering
+// ---------------------------------------------------------------------------
+
+describe("ErrorBoundary — rendering", () => {
+  it("renders the heading", () => {
+    render(<ErrorBoundary error={makeError("boom")} reset={() => {}} />);
+    expect(
+      screen.getByRole("heading", { name: /something went wrong/i })
+    ).toBeInTheDocument();
+  });
+
+  it("renders the error message when one is provided", () => {
+    render(
+      <ErrorBoundary error={makeError("Network timeout")} reset={() => {}} />
+    );
+    expect(screen.getByText("Network timeout")).toBeInTheDocument();
+  });
+
+  it("renders fallback copy when error.message is empty", () => {
+    render(<ErrorBoundary error={makeError("")} reset={() => {}} />);
+    expect(
+      screen.getByText(/an unexpected error occurred/i)
+    ).toBeInTheDocument();
+  });
+
+  it("renders a Try again button", () => {
+    render(<ErrorBoundary error={makeError("oops")} reset={() => {}} />);
+    expect(
+      screen.getByRole("button", { name: /try again/i })
+    ).toBeInTheDocument();
+  });
+
+  it("wraps error message in a role=alert region", () => {
+    render(<ErrorBoundary error={makeError("oops")} reset={() => {}} />);
+    const alert = screen.getByRole("alert");
+    expect(alert).toBeInTheDocument();
+    expect(alert).toHaveTextContent("oops");
+  });
+
+  it("renders the main landmark with id=main-content", () => {
+    render(<ErrorBoundary error={makeError("oops")} reset={() => {}} />);
+    const main = screen.getByRole("main");
+    expect(main).toHaveAttribute("id", "main-content");
+    expect(main).toHaveAttribute("tabIndex", "-1");
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Button component integration
+// ---------------------------------------------------------------------------
+
+describe("ErrorBoundary — Button component", () => {
+  it("uses the Button component for Try again action", () => {
+    render(<ErrorBoundary error={makeError("oops")} reset={() => {}} />);
+    const button = screen.getByRole("button", { name: /try again/i });
+    expect(button).toHaveAttribute("type", "button");
+    // Button component applies specific classes
+    expect(button.className).toMatch(/rounded-full/);
+    expect(button.className).toMatch(/px-5/);
+    expect(button.className).toMatch(/py-2/);
+  });
+
+  it("Button has primary variant styling", () => {
+    render(<ErrorBoundary error={makeError("oops")} reset={() => {}} />);
+    const button = screen.getByRole("button", { name: /try again/i });
+    expect(button.className).toMatch(/bg-black/);
+    expect(button.className).toMatch(/text-white/);
+  });
+
+  it("Button has focus-visible outline", () => {
+    render(<ErrorBoundary error={makeError("oops")} reset={() => {}} />);
+    const button = screen.getByRole("button", { name: /try again/i });
+    expect(button.className).toMatch(/focus-visible:outline/);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// reset callback
+// ---------------------------------------------------------------------------
+
+describe("ErrorBoundary — reset interaction", () => {
+  it("calls reset once when Try again is clicked", () => {
+    const reset = jest.fn();
+    render(<ErrorBoundary error={makeError("oops")} reset={reset} />);
+    fireEvent.click(screen.getByRole("button", { name: /try again/i }));
+    expect(reset).toHaveBeenCalledTimes(1);
+  });
+
+  it("calls reset again on each subsequent click", () => {
+    const reset = jest.fn();
+    render(<ErrorBoundary error={makeError("oops")} reset={reset} />);
+    const btn = screen.getByRole("button", { name: /try again/i });
+    fireEvent.click(btn);
+    fireEvent.click(btn);
+    fireEvent.click(btn);
+    expect(reset).toHaveBeenCalledTimes(3);
+  });
+
+  it("does not call reset on render, only on click", () => {
+    const reset = jest.fn();
+    render(<ErrorBoundary error={makeError("oops")} reset={reset} />);
+    expect(reset).not.toHaveBeenCalled();
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Production safety — no stack traces in the DOM
+// ---------------------------------------------------------------------------
+
+describe("ErrorBoundary — production safety", () => {
+  it("does not render the error stack trace", () => {
+    const err = makeError("bad thing");
+    err.stack = "Error: bad thing\n    at Component (file.tsx:10:5)";
+    const { container } = render(
+      <ErrorBoundary error={err} reset={() => {}} />
+    );
+    // The raw stack string must never appear anywhere in the rendered output.
+    expect(container.textContent).not.toContain(err.stack);
+    expect(container.textContent).not.toMatch(/at Component/);
+  });
+
+  it("does not render any stack-like content even when error has a long stack", () => {
+    const err = makeError("crash");
+    err.stack = [
+      "Error: crash",
+      "    at ErrorBoundary (error.tsx:10:5)",
+      "    at renderWithHooks (react-dom.development.js:14985:18)",
+      "    at mountIndeterminateComponent (react-dom.development.js:17811:13)",
+    ].join("\n");
+    const { container } = render(
+      <ErrorBoundary error={err} reset={() => {}} />
+    );
+    expect(container.textContent).not.toMatch(/renderWithHooks/);
+    expect(container.textContent).not.toMatch(/mountIndeterminateComponent/);
+  });
+
+  it("only renders error.message, never error.stack", () => {
+    const err = makeError("User-friendly message");
+    err.stack = "Error: User-friendly message\n    at dangerous stack trace";
+    const { container } = render(
+      <ErrorBoundary error={err} reset={() => {}} />
+    );
+    expect(container.textContent).toContain("User-friendly message");
+    expect(container.textContent).not.toContain("dangerous stack trace");
+  });
+});
+
+// ---------------------------------------------------------------------------
+// console.error logging
+// ---------------------------------------------------------------------------
+
+describe("ErrorBoundary — error logging", () => {
+  it("logs the error via console.error on mount", () => {
+    const err = makeError("logged error");
+    render(<ErrorBoundary error={err} reset={() => {}} />);
+    expect(console.error).toHaveBeenCalledWith(
+      "App error boundary caught:",
+      err
+    );
+  });
+
+  it("logs the error digest when present", () => {
+    const err = makeError("crash", "abc-123");
+    render(<ErrorBoundary error={err} reset={() => {}} />);
+    expect(console.error).toHaveBeenCalledWith("Error digest:", "abc-123");
+  });
+
+  it("does not log digest when digest is absent", () => {
+    const err = makeError("crash");
+    render(<ErrorBoundary error={err} reset={() => {}} />);
+    expect(console.error).not.toHaveBeenCalledWith(
+      expect.stringMatching(/digest/),
+      expect.anything()
+    );
+  });
+
+  it("does not log digest when digest is undefined", () => {
+    const err = makeError("crash", undefined);
+    render(<ErrorBoundary error={err} reset={() => {}} />);
+    const calls = (console.error as jest.Mock).mock.calls;
+    const digestCalls = calls.filter((call) =>
+      call.some((arg: unknown) => typeof arg === "string" && arg.includes("digest"))
+    );
+    expect(digestCalls).toHaveLength(0);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Dark mode styling
+// ---------------------------------------------------------------------------
+
+describe("ErrorBoundary — dark mode", () => {
+  it("applies dark mode classes to the error message", () => {
+    render(<ErrorBoundary error={makeError("oops")} reset={() => {}} />);
+    const alert = screen.getByRole("alert");
+    expect(alert.className).toMatch(/dark:text-zinc-400/);
+  });
+
+  it("main landmark supports dark mode focus styles", () => {
+    render(<ErrorBoundary error={makeError("oops")} reset={() => {}} />);
+    const main = screen.getByRole("main");
+    expect(main.className).toMatch(/focus:outline-none/);
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Accessibility
+// ---------------------------------------------------------------------------
+
+describe("ErrorBoundary — accessibility", () => {
+  it("error message is announced via role=alert", () => {
+    render(<ErrorBoundary error={makeError("Critical error")} reset={() => {}} />);
+    const alert = screen.getByRole("alert");
+    expect(alert).toHaveTextContent("Critical error");
+  });
+
+  it("Try again button is keyboard operable", () => {
+    const reset = jest.fn();
+    render(<ErrorBoundary error={makeError("oops")} reset={reset} />);
+    const button = screen.getByRole("button", { name: /try again/i });
+    
+    // Simulate keyboard activation
+    button.focus();
+    fireEvent.keyDown(button, { key: "Enter", code: "Enter" });
+    fireEvent.click(button);
+    
+    expect(reset).toHaveBeenCalled();
+  });
+
+  it("main landmark can receive focus for skip links", () => {
+    render(<ErrorBoundary error={makeError("oops")} reset={() => {}} />);
+    const main = screen.getByRole("main");
+    expect(main).toHaveAttribute("tabIndex", "-1");
+    expect(main).toHaveAttribute("id", "main-content");
+  });
+});
+
+// ---------------------------------------------------------------------------
+// Edge cases
+// ---------------------------------------------------------------------------
+
+describe("ErrorBoundary — edge cases", () => {
+  it("handles error with undefined message", () => {
+    const err = new Error() as Error & { digest?: string };
+    render(<ErrorBoundary error={err} reset={() => {}} />);
+    expect(
+      screen.getByText(/an unexpected error occurred/i)
+    ).toBeInTheDocument();
+  });
+
+  it("handles error with null-like properties", () => {
+    const err = {
+      message: "",
+      name: "Error",
+    } as Error & { digest?: string };
+    render(<ErrorBoundary error={err} reset={() => {}} />);
+    expect(screen.getByRole("alert")).toHaveTextContent(
+      /an unexpected error occurred/i
+    );
+  });
+
+  it("handles very long error messages without breaking layout", () => {
+    const longMessage = "A".repeat(500);
+    render(<ErrorBoundary error={makeError(longMessage)} reset={() => {}} />);
+    expect(screen.getByRole("alert")).toHaveTextContent(longMessage);
+  });
+
+  it("renders correctly when error message contains HTML-like characters", () => {
+    render(
+      <ErrorBoundary
+        error={makeError("<script>alert('xss')</script>")}
+        reset={() => {}}
+      />
+    );
+    const alert = screen.getByRole("alert");
+    // Text content should be escaped, not parsed as HTML
+    expect(alert.textContent).toBe("<script>alert('xss')</script>");
+  });
+});
diff --git a/src/app/error.tsx b/src/app/error.tsx
index c10688e..bbf62ce 100644
--- a/src/app/error.tsx
+++ b/src/app/error.tsx
@@ -1,6 +1,7 @@
 "use client";
 
 import { useEffect } from "react";
+import { Button } from "@/components/Button";
 
 export default function ErrorBoundary({
   error,
@@ -11,6 +12,9 @@ export default function ErrorBoundary({
 }) {
   useEffect(() => {
     console.error("App error boundary caught:", error);
+    if (error.digest) {
+      console.error("Error digest:", error.digest);
+    }
   }, [error]);
 
   return (
@@ -20,16 +24,12 @@ export default function ErrorBoundary({
       className="mx-auto flex min-h-[60vh] max-w-xl flex-col items-center justify-center gap-4 p-8 text-center focus:outline-none"
     >
       <h1 className="text-2xl font-semibold">Something went wrong.</h1>
-      <p className="text-sm text-zinc-600 dark:text-zinc-400">
-        {error.message || "Unexpected error."}
-      </p>
-      <button
-        type="button"
-        onClick={reset}
-        className="rounded-full bg-black px-5 py-2 text-sm font-medium text-white focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-blue-500"
-      >
+      <div role="alert" className="text-sm text-zinc-600 dark:text-zinc-400">
+        {error.message || "An unexpected error occurred."}
+      </div>
+      <Button type="button" onClick={reset}>
         Try again
-      </button>
+      </Button>
     </main>
   );
 }
diff --git a/src/app/not-found.test.tsx b/src/app/not-found.test.tsx
new file mode 100644
index 0000000..cd03a6d
--- /dev/null
+++ b/src/app/not-found.test.tsx
@@ -0,0 +1,129 @@
+import { render, screen } from "@testing-library/react";
+import NotFound from "./not-found";
+
+describe("NotFound", () => {
+  it("renders the 404 heading", () => {
+    render(<NotFound />);
+    expect(screen.getByRole("heading", { name: "404" })).toBeInTheDocument();
+  });
+
+  it("renders the explanatory text", () => {
+    render(<NotFound />);
+    expect(screen.getByText("That page does not exist.")).toBeInTheDocument();
+  });
+
+  it("renders the main landmark", () => {
+    render(<NotFound />);
+    const main = screen.getByRole("main");
+    expect(main).toBeInTheDocument();
+    expect(main).toHaveAttribute("id", "main-content");
+    expect(main).toHaveAttribute("tabIndex", "-1");
+  });
+
+  it("renders the primary Back to home button", () => {
+    render(<NotFound />);
+    const backButton = screen.getByRole("link", { name: "Back to home" });
+    expect(backButton).toBeInTheDocument();
+    expect(backButton).toHaveAttribute("href", "/");
+  });
+
+  it("renders the helpful links navigation landmark", () => {
+    render(<NotFound />);
+    const nav = screen.getByRole("navigation", { name: "Helpful links" });
+    expect(nav).toBeInTheDocument();
+  });
+
+  it("renders a semantic list inside the navigation", () => {
+    render(<NotFound />);
+    const nav = screen.getByRole("navigation", { name: "Helpful links" });
+    const list = screen.getByRole("list");
+    expect(nav).toContainElement(list);
+  });
+
+  it("renders all four recovery links with correct labels and hrefs", () => {
+    render(<NotFound />);
+
+    const recoveryLinks = [
+      { name: "Home", href: "/" },
+      { name: "Services", href: "/services" },
+      { name: "Stats", href: "/stats" },
+      { name: "Docs", href: "/docs" },
+    ] as const;
+
+    const nav = screen.getByRole("navigation", { name: "Helpful links" });
+
+    for (const { name, href } of recoveryLinks) {
+      const link = screen.getByRole("link", { name });
+      expect(link).toBeInTheDocument();
+      expect(link).toHaveAttribute("href", href);
+      expect(nav).toContainElement(link);
+    }
+  });
+
+  it("renders exactly four list items in the navigation", () => {
+    render(<NotFound />);
+    const nav = screen.getByRole("navigation", { name: "Helpful links" });
+    const listItems = screen.getAllByRole("listitem");
+    expect(listItems).toHaveLength(4);
+    listItems.forEach((item) => {
+      expect(nav).toContainElement(item);
+    });
+  });
+
+  it("does not render any links to routes that do not exist", () => {
+    render(<NotFound />);
+    // Ensure we're only linking to routes that actually exist
+    const allLinks = screen.getAllByRole("link");
+    const hrefs = allLinks.map((link) => link.getAttribute("href"));
+    
+    // These are valid routes
+    expect(hrefs).toContain("/");
+    expect(hrefs).toContain("/services");
+    expect(hrefs).toContain("/stats");
+    expect(hrefs).toContain("/docs");
+    
+    // Ensure we don't link to non-existent routes
+    expect(hrefs).not.toContain("/nonexistent");
+    expect(hrefs).not.toContain("/fake-route");
+  });
+
+  it("makes the primary button keyboard-accessible with focus-visible outline", () => {
+    render(<NotFound />);
+    const backButton = screen.getByRole("link", { name: "Back to home" });
+    expect(backButton).toHaveClass("focus-visible:outline");
+  });
+
+  it("makes all recovery links keyboard-accessible with focus-visible outline", () => {
+    render(<NotFound />);
+    const nav = screen.getByRole("navigation", { name: "Helpful links" });
+    const links = screen.getAllByRole("link").filter((link) => nav.contains(link));
+    
+    links.forEach((link) => {
+      expect(link).toHaveClass("focus-visible:outline");
+    });
+  });
+
+  it("applies dark mode classes to the primary button", () => {
+    render(<NotFound />);
+    const backButton = screen.getByRole("link", { name: "Back to home" });
+    expect(backButton).toHaveClass("dark:bg-white");
+    expect(backButton).toHaveClass("dark:text-black");
+  });
+
+  it("applies dark mode classes to recovery links", () => {
+    render(<NotFound />);
+    const nav = screen.getByRole("navigation", { name: "Helpful links" });
+    const links = screen.getAllByRole("link").filter((link) => nav.contains(link));
+    
+    links.forEach((link) => {
+      expect(link).toHaveClass("dark:text-blue-400");
+      expect(link).toHaveClass("dark:hover:text-blue-300");
+    });
+  });
+
+  it("renders exactly five total links (one primary + four recovery)", () => {
+    render(<NotFound />);
+    const allLinks = screen.getAllByRole("link");
+    expect(allLinks).toHaveLength(5);
+  });
+});
diff --git a/src/app/not-found.tsx b/src/app/not-found.tsx
index e1561b6..db32802 100644
--- a/src/app/not-found.tsx
+++ b/src/app/not-found.tsx
@@ -13,10 +13,47 @@ export default function NotFound() {
       </p>
       <Link
         href="/"
-        className="rounded-full bg-black px-5 py-2 text-sm font-medium text-white focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-blue-500"
+        className="rounded-full bg-black px-5 py-2 text-sm font-medium text-white focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-blue-500 dark:bg-white dark:text-black"
       >
         Back to home
       </Link>
+
+      <nav aria-label="Helpful links" className="mt-4">
+        <ul className="flex flex-col gap-2 text-sm">
+          <li>
+            <Link
+              href="/"
+              className="text-blue-600 underline hover:text-blue-800 focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-blue-500 dark:text-blue-400 dark:hover:text-blue-300"
+            >
+              Home
+            </Link>
+          </li>
+          <li>
+            <Link
+              href="/services"
+              className="text-blue-600 underline hover:text-blue-800 focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-blue-500 dark:text-blue-400 dark:hover:text-blue-300"
+            >
+              Services
+            </Link>
+          </li>
+          <li>
+            <Link
+              href="/stats"
+              className="text-blue-600 underline hover:text-blue-800 focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-blue-500 dark:text-blue-400 dark:hover:text-blue-300"
+            >
+              Stats
+            </Link>
+          </li>
+          <li>
+            <Link
+              href="/docs"
+              className="text-blue-600 underline hover:text-blue-800 focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-blue-500 dark:text-blue-400 dark:hover:text-blue-300"
+            >
+              Docs
+            </Link>
+          </li>
+        </ul>
+      </nav>
     </main>
   );
 }