feat: WebSub Atom support, HTML processing via linkedom, W3C badges

WebSub / PubSubHubbub:
- Hub now accepts both /rss/:id and /atom/:id topic URLs
- WebSubSubscription stores format ("rss" | "atom")
- notifySubscribers sends RSS or Atom XML with correct Content-Type
- verifyAndStoreSubscription sends correct topic URL per format
- CI paths-ignore docs/** to skip deploy on docs-only changes

HTML processing (linkedom + escape-html):
- New html-processor.ts: body extraction, script/iframe/object removal,
  event handler + javascript: URL stripping, mso-* style cleanup,
  plain text → <pre> with HTML escaping via escape-html
- feed-generator.ts and entries.ts use processEmailContent

Admin UI:
- W3C validation badges (Atom + RSS) on feed detail page

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/routes/admin/emails.tsx

@@ -116,6 +116,30 @@ emailsRouter.get("/feeds/:feedId/emails", async (c) => {
             <CopyField label="RSS Feed:" value={rssUrl} />
             <CopyField label="Atom Feed:" value={atomUrl} />
           </div>
+          <div class="feed-validate">
+            <a
+              href={`https://validator.w3.org/feed/check.cgi?url=${encodeURIComponent(atomUrl)}`}
+              target="_blank"
+              rel="noopener noreferrer"
+            >
+              <img
+                src="https://validator.w3.org/feed/images/valid-atom.png"
+                alt="[Valid Atom 1.0]"
+                title="Validate my Atom 1.0 feed"
+              />
+            </a>
+            <a
+              href={`https://validator.w3.org/feed/check.cgi?url=${encodeURIComponent(rssUrl)}`}
+              target="_blank"
+              rel="noopener noreferrer"
+            >
+              <img
+                src="https://validator.w3.org/feed/images/valid-rss-rogers.png"
+                alt="[Valid RSS]"
+                title="Validate my RSS feed"
+              />
+            </a>
+          </div>
         </div>
 
         <h2>

src/routes/entries.ts

@@ -1,6 +1,7 @@
 import { Context } from "hono";
 import { html, raw } from "hono/html";
 import { Env, FeedMetadata, EmailData } from "../types";
+import { processEmailContent } from "../utils/html-processor";
 
 export async function handle(c: Context<{ Bindings: Env }>): Promise<Response> {
   const feedId = c.req.param("feedId");
@@ -82,7 +83,9 @@ export async function handle(c: Context<{ Bindings: Env }>): Promise<Response> {
             <dt>Date:</dt>
             <dd>${new Date(emailData.receivedAt).toUTCString()}</dd>
           </dl>
-          <div class="content">${raw(emailData.content)}</div>
+          <div class="content">
+            ${raw(processEmailContent(emailData.content))}
+          </div>
         </body>
       </html>`,
   );

src/routes/hub.test.ts

@@ -124,6 +124,21 @@ describe("POST /hub — input validation", () => {
     expect(res.status).toBe(400);
   });
 
+  it("returns 400 when hub.topic uses an unsupported path (not rss or atom)", async () => {
+    const app = makeApp();
+    const env = createMockEnv();
+    const res = await app.request(
+      "/hub",
+      hubBody({
+        "hub.mode": "subscribe",
+        "hub.topic": `https://${env.DOMAIN}/feed/feed1`,
+        "hub.callback": "https://cb.example/sub",
+      }),
+      env,
+    );
+    expect(res.status).toBe(400);
+  });
+
   it("returns 400 when hub.secret exceeds 200 bytes", async () => {
     const app = makeApp();
     const env = createMockEnv();
@@ -213,10 +228,51 @@ describe("POST /hub — subscribe", () => {
     );
     expect(res.status).toBe(404);
   });
+
+  it("returns 202 for valid Atom subscribe request", async () => {
+    const app = makeApp();
+    const env = createMockEnv();
+    await env.EMAIL_STORAGE.put(
+      "feed:feed1:config",
+      JSON.stringify({ title: "Feed 1" }),
+    );
+    server.use(
+      http.get("https://cb.example/sub", ({ request }) => {
+        const challenge =
+          new URL(request.url).searchParams.get("hub.challenge") ?? "";
+        return HttpResponse.text(challenge);
+      }),
+    );
+    const res = await app.request(
+      "/hub",
+      hubBody({
+        "hub.mode": "subscribe",
+        "hub.topic": `https://${env.DOMAIN}/atom/feed1`,
+        "hub.callback": "https://cb.example/sub",
+      }),
+      env,
+    );
+    expect(res.status).toBe(202);
+  });
+
+  it("returns 404 for Atom topic when feed does not exist", async () => {
+    const app = makeApp();
+    const env = createMockEnv();
+    const res = await app.request(
+      "/hub",
+      hubBody({
+        "hub.mode": "subscribe",
+        "hub.topic": `https://${env.DOMAIN}/atom/nonexistent`,
+        "hub.callback": "https://cb.example/sub",
+      }),
+      env,
+    );
+    expect(res.status).toBe(404);
+  });
 });
 
 describe("POST /hub — unsubscribe", () => {
-  it("returns 202 for valid unsubscribe request", async () => {
+  it("returns 202 for valid RSS unsubscribe request", async () => {
     const app = makeApp();
     const env = createMockEnv();
     await env.EMAIL_STORAGE.put(
@@ -241,4 +297,30 @@ describe("POST /hub — unsubscribe", () => {
     );
     expect(res.status).toBe(202);
   });
+
+  it("returns 202 for valid Atom unsubscribe request", async () => {
+    const app = makeApp();
+    const env = createMockEnv();
+    await env.EMAIL_STORAGE.put(
+      "feed:feed1:config",
+      JSON.stringify({ title: "Feed 1" }),
+    );
+    server.use(
+      http.get("https://cb.example/sub", ({ request }) => {
+        const challenge =
+          new URL(request.url).searchParams.get("hub.challenge") ?? "";
+        return HttpResponse.text(challenge);
+      }),
+    );
+    const res = await app.request(
+      "/hub",
+      hubBody({
+        "hub.mode": "unsubscribe",
+        "hub.topic": `https://${env.DOMAIN}/atom/feed1`,
+        "hub.callback": "https://cb.example/sub",
+      }),
+      env,
+    );
+    expect(res.status).toBe(202);
+  });
 });

src/routes/hub.ts

@@ -59,18 +59,19 @@ hubRouter.post("/", async (c) => {
     return c.text("Bad Request: hub.callback must use HTTPS", 400);
   }
 
-  // Validate that topic matches a known RSS feed on this hub
+  // Validate that topic matches a known RSS or Atom feed on this hub
   const topicPattern = new RegExp(
-    `^https://${env.DOMAIN.replaceAll(".", "\\.")}/rss/([^/]+)$`,
+    `^https://${env.DOMAIN.replaceAll(".", "\\.")}/(rss|atom)/([^/]+)$`,
   );
   const match = topic.match(topicPattern);
   if (!match) {
     return c.text(
-      "Bad Request: hub.topic must be an RSS feed URL on this hub",
+      "Bad Request: hub.topic must be an RSS or Atom feed URL on this hub",
       400,
     );
   }
-  const feedId = match[1];
+  const format = match[1] as "rss" | "atom";
+  const feedId = match[2];
 
   // Verify the feed exists before accepting any subscription
   const feedConfig = await env.EMAIL_STORAGE.get(
@@ -99,6 +100,7 @@ hubRouter.post("/", async (c) => {
         callbackUrl as string,
         secret as string | undefined,
         leaseSeconds,
+        format,
         env,
       ),
     );