diff --git a/web/src/app/community/d/[id]/page.tsx b/web/src/app/community/d/[id]/page.tsx
index f243053f5..18e411a48 100644
--- a/web/src/app/community/d/[id]/page.tsx
+++ b/web/src/app/community/d/[id]/page.tsx
@@ -22,7 +22,9 @@ export async function generateMetadata(props: RouteParams): Promise<Metadata> {
   if (!communityEnabled()) return {};
   const { id } = await props.params;
   const deck = await getDeck(id);
-  if (!deck || deck.visibility === "private") return {};
+  // A gone deck takes community/not-found.tsx's title, as a gone pattern does.
+  if (!deck) notFound();
+  if (deck.visibility === "private") return {};
   return {
     title: `${deck.title} / Patternflow Community`,
     description:
diff --git a/web/src/app/community/not-found.test.tsx b/web/src/app/community/not-found.test.tsx
new file mode 100644
index 000000000..420ce94c0
--- /dev/null
+++ b/web/src/app/community/not-found.test.tsx
@@ -0,0 +1,122 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { render, screen } from "@testing-library/react";
+import { afterAll, beforeAll, describe, expect, it, vi } from "vitest";
+import CommunityNotFound, { metadata } from "./not-found";
+
+// A deleted pattern's old address, a deck or profile that never existed, and
+// somebody else's private work all 404. They used to land on the site's root
+// 404: "404", a link to the landing page, no community header, and a tab that
+// still read "Community / Patternflow". This file now draws them inside the
+// community layout, and each page's metadata 404s with it, so a gone row takes
+// this file's title instead of the layout's.
+
+// The pages' client halves run pattern code in sandboxes; metadata never
+// reaches them.
+vi.mock("./p/[id]/PatternDetailClient", () => ({ default: () => null }));
+vi.mock("./d/[id]/DeckDetailClient", () => ({ default: () => null }));
+vi.mock("@/components/community/DeckCard", () => ({ default: () => null }));
+vi.mock("@/components/community/PatternCard", () => ({ default: () => null }));
+vi.mock("@/components/community/SignOutLink", () => ({ default: () => null }));
+
+const ENV_KEYS = ["COMMUNITY_DB_PATH", "COMMUNITY_ENABLED", "BETTER_AUTH_SECRET"] as const;
+const savedEnv = Object.fromEntries(ENV_KEYS.map((key) => [key, process.env[key]]));
+let tmp = "";
+
+beforeAll(async () => {
+  // The database is a lazy singleton keyed off these variables, so they are
+  // set before anything imports it.
+  tmp = fs.mkdtempSync(path.join(os.tmpdir(), "pf-not-found-"));
+  process.env.COMMUNITY_DB_PATH = path.join(tmp, "test.db");
+  process.env.COMMUNITY_ENABLED = "1";
+  process.env.BETTER_AUTH_SECRET = "not-found-test-secret-not-a-real-one";
+
+  const { eq } = await import("drizzle-orm");
+  const { getAuth } = await import("@/lib/community/server/auth");
+  const { getDb } = await import("@/lib/community/server/db");
+  const schema = await import("@/lib/community/server/schema");
+
+  await getAuth().api.signUpEmail({
+    body: { email: "ada@patternflow.local", password: "not-found-test-password", name: "ada", username: "ada" },
+  });
+  const db = getDb();
+  const [ada] = await db
+    .select({ id: schema.user.id })
+    .from(schema.user)
+    .where(eq(schema.user.username, "ada"))
+    .limit(1);
+  const userId = ada!.id;
+  const now = new Date();
+  await db.insert(schema.patterns).values({
+    id: "private1", userId, title: "Night bus window", code: "// js", visibility: "private", createdAt: now, updatedAt: now,
+  });
+  await db.insert(schema.decks).values({
+    id: "private2", userId, title: "Late set", visibility: "private", createdAt: now, updatedAt: now,
+  });
+}, 30_000);
+
+afterAll(() => {
+  for (const key of ENV_KEYS) {
+    if (savedEnv[key] === undefined) delete process.env[key];
+    else process.env[key] = savedEnv[key];
+  }
+  if (tmp) fs.rmSync(tmp, { recursive: true, force: true });
+});
+
+describe("the community's 404", () => {
+  it("says why the page is gone and links to the wall, not the landing page", () => {
+    render(<CommunityNotFound />);
+    expect(screen.getByRole("heading", { level: 1 })).toHaveTextContent("Nothing at this address.");
+    expect(screen.getByText(/deleted, or its owner made it private/)).toBeInTheDocument();
+    const links = screen.getAllByRole("link");
+    expect(links.map((link) => link.getAttribute("href"))).toEqual(["/community/patterns"]);
+    expect(links[0]).toHaveTextContent("Browse patterns");
+  });
+
+  it("names itself in the tab", () => {
+    expect(metadata.title).toBe("Not found / Patternflow Community");
+  });
+});
+
+// notFound() throws an error whose digest names the status.
+const NOT_FOUND = { digest: "NEXT_HTTP_ERROR_FALLBACK;404" };
+
+describe("a gone row's metadata", () => {
+  it("404s for a pattern that is not there", async () => {
+    const { generateMetadata } = await import("./p/[id]/page");
+    const props = { params: Promise.resolve({ id: "0000000000000000" }), searchParams: Promise.resolve({}) };
+    await expect(generateMetadata(props)).rejects.toMatchObject(NOT_FOUND);
+  });
+
+  it("404s for a deck that is not there", async () => {
+    const { generateMetadata } = await import("./d/[id]/page");
+    await expect(generateMetadata({ params: Promise.resolve({ id: "0000000000000000" }) })).rejects.toMatchObject(
+      NOT_FOUND,
+    );
+  });
+
+  it("404s for a profile that is not there", async () => {
+    const { generateMetadata } = await import("./u/[username]/page");
+    await expect(generateMetadata({ params: Promise.resolve({ username: "nobody404" }) })).rejects.toMatchObject(
+      NOT_FOUND,
+    );
+  });
+
+  // Metadata cannot tell the owner from a visitor, and the owner opens these.
+  it("stays generic for a private pattern or deck, which its owner can still open", async () => {
+    const pattern = await import("./p/[id]/page");
+    const deck = await import("./d/[id]/page");
+    await expect(
+      pattern.generateMetadata({ params: Promise.resolve({ id: "private1" }), searchParams: Promise.resolve({}) }),
+    ).resolves.toEqual({});
+    await expect(deck.generateMetadata({ params: Promise.resolve({ id: "private2" }) })).resolves.toEqual({});
+  });
+
+  it("still names a profile that is there", async () => {
+    const { generateMetadata } = await import("./u/[username]/page");
+    await expect(generateMetadata({ params: Promise.resolve({ username: "ada" }) })).resolves.toMatchObject({
+      title: "@ada / Patternflow Community",
+    });
+  });
+});
diff --git a/web/src/app/community/not-found.tsx b/web/src/app/community/not-found.tsx
new file mode 100644
index 000000000..4d377026e
--- /dev/null
+++ b/web/src/app/community/not-found.tsx
@@ -0,0 +1,29 @@
+import Link from "next/link";
+import type { Metadata } from "next";
+import styles from "@/components/community/Community.module.css";
+
+// A pattern, deck or profile page calls notFound() for a row that is gone and
+// for one its owner made private (a 404, not a 403, so the id is never
+// confirmed). Without this file those links fell through to the site's root
+// 404, which drops the community header and tabs and links to the landing
+// page. Here the layout stays around it and the way on is the wall.
+
+export const metadata: Metadata = {
+  title: "Not found / Patternflow Community",
+};
+
+export default function CommunityNotFound() {
+  return (
+    <div className={styles.emptyPanel}>
+      <span className={styles.emptyKicker}>404 · not here</span>
+      <h1 className={styles.emptyTitle}>Nothing at this address.</h1>
+      <p className={styles.emptyBody}>
+        Whatever was here has been deleted, or its owner made it private. A mistyped link
+        lands here too.
+      </p>
+      <Link href="/community/patterns" className={styles.emptyCta}>
+        Browse patterns →
+      </Link>
+    </div>
+  );
+}
diff --git a/web/src/app/community/p/[id]/page.tsx b/web/src/app/community/p/[id]/page.tsx
index e8616afec..42ecbeb46 100644
--- a/web/src/app/community/p/[id]/page.tsx
+++ b/web/src/app/community/p/[id]/page.tsx
@@ -40,9 +40,12 @@ export async function generateMetadata(props: RouteParams): Promise<Metadata> {
   if (!communityEnabled()) return {};
   const { id } = await props.params;
   const pattern = await getPatternOnce(id);
+  // A gone pattern takes community/not-found.tsx's title. The page itself
+  // 404s too, but the tab only reads what this function decides.
+  if (!pattern) notFound();
   // Metadata is what previews and crawlers read, so a private pattern's title
   // must not surface here — even the owner's tab goes generic.
-  if (!pattern || pattern.visibility === "private") return {};
+  if (pattern.visibility === "private") return {};
   return {
     title: `${pattern.title} / Patternflow Community`,
     description: pattern.description ?? `An LED matrix pattern by ${pattern.displayUsername ?? pattern.username}.`,
diff --git a/web/src/app/community/u/[username]/page.tsx b/web/src/app/community/u/[username]/page.tsx
index a447a3f12..a8ed73ff0 100644
--- a/web/src/app/community/u/[username]/page.tsx
+++ b/web/src/app/community/u/[username]/page.tsx
@@ -30,7 +30,8 @@ export async function generateMetadata(props: RouteParams): Promise<Metadata> {
   if (!communityEnabled()) return {};
   const { username } = await props.params;
   const profile = await getUserByUsername(username.toLowerCase());
-  if (!profile) return {};
+  // A gone account takes community/not-found.tsx's title, as a gone pattern does.
+  if (!profile) notFound();
   const handle = profile.displayUsername ?? profile.username;
   return {
     title: `@${handle} / Patternflow Community`,