refactor: extract url helpers, add EMAIL_DOMAIN support

- Add src/utils/urls.ts with baseUrl, feedRssUrl, feedAtomUrl, feedUrl,
  feedEmailAddress, feedTopicPattern
- Add optional EMAIL_DOMAIN env var so web domain and email domain can
  differ (e.g. demo.kill-the.news serves feeds, @kill-the.news receives mail)
- Replace all inline domain template literals with the new helpers
- Remove unused site_url/feed_url fields from FeedConfig
- Remove unused feedPath param from fetchFeedData
- Extract verifyCallback() to deduplicate verifyAndStoreSubscription /
  verifyAndDeleteSubscription

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/email-processor.test.ts

@@ -220,8 +220,6 @@ describe("processEmail", () => {
       JSON.stringify({
         title: "Test",
         language: "en",
-        site_url: "https://example.com",
-        feed_url: `https://example.com/rss/${VALID_FEED_ID}`,
         created_at: Date.now(),
       }),
     );

src/routes/admin.tsx

@@ -8,6 +8,7 @@ import { ADMIN_COOKIE_MAX_AGE } from "../config/constants";
 import { logger } from "../lib/logger";
 import { Layout, clampText } from "./admin/ui";
 import { listAllFeeds, updateFeedInList } from "./admin/helpers";
+import { feedRssUrl, feedAtomUrl, feedEmailAddress } from "../utils/urls";
 import { feedsRouter } from "./admin/feeds";
 import { emailsRouter } from "./admin/emails";
 import { dashboardScript } from "../scripts/generated/dashboard";
@@ -601,9 +602,9 @@ app.get("/", async (c) => {
                   </thead>
                   <tbody id="feed-table-body">
                     {feedsWithConfig.map((feed) => {
-                      const emailAddress = `${feed.id}@${env.DOMAIN}`;
-                      const rssUrl = `https://${env.DOMAIN}/rss/${feed.id}`;
-                      const atomUrl = `https://${env.DOMAIN}/atom/${feed.id}`;
+                      const emailAddress = feedEmailAddress(feed.id, env);
+                      const rssUrl = feedRssUrl(feed.id, env);
+                      const atomUrl = feedAtomUrl(feed.id, env);
                       const titleDisplay = clampText(feed.title, 160);
                       const titleHover = clampText(feed.title, 1000);
                       const sortTitle = titleHover.toLowerCase();
@@ -712,9 +713,9 @@ app.get("/", async (c) => {
 
             <ul class="feed-list">
               {feedsWithConfig.map((feed) => {
-                const emailAddress = `${feed.id}@${env.DOMAIN}`;
-                const rssUrl = `https://${env.DOMAIN}/rss/${feed.id}`;
-                const atomUrl = `https://${env.DOMAIN}/atom/${feed.id}`;
+                const emailAddress = feedEmailAddress(feed.id, env);
+                const rssUrl = feedRssUrl(feed.id, env);
+                const atomUrl = feedAtomUrl(feed.id, env);
                 const titleDisplay = clampText(feed.title, 140);
                 const titleHover = clampText(feed.title, 1000);
                 const descDisplay = clampText(feed.description || "", 240);

src/routes/admin/emails.tsx

@@ -9,6 +9,7 @@ import {
 import { logger } from "../../lib/logger";
 import { Layout, clampText } from "./ui";
 import { deleteKeysWithConcurrency } from "./helpers";
+import { feedRssUrl, feedAtomUrl, feedEmailAddress } from "../../utils/urls";
 import { emailsPageScript } from "../../scripts/generated/emails-page";
 
 type AppEnv = { Bindings: Env };
@@ -91,9 +92,9 @@ emailsRouter.get("/feeds/:feedId/emails", async (c) => {
     return c.text("Feed not found", 404);
   }
 
-  const emailAddress = `${feedId}@${env.DOMAIN}`;
-  const rssUrl = `https://${env.DOMAIN}/rss/${feedId}`;
-  const atomUrl = `https://${env.DOMAIN}/atom/${feedId}`;
+  const emailAddress = feedEmailAddress(feedId, env);
+  const rssUrl = feedRssUrl(feedId, env);
+  const atomUrl = feedAtomUrl(feedId, env);
 
   return c.html(
     <Layout title={`${feedConfig.title} - Emails`}>
@@ -426,7 +427,7 @@ emailsRouter.get("/emails/:emailKey", async (c) => {
               <CopyField label="From:" value={emailData.from} />
               <CopyField
                 label="To:"
-                value={`${feedId}@${env.DOMAIN}`}
+                value={feedEmailAddress(feedId, env)}
               />
             </div>
           </div>

src/routes/admin/feeds.tsx

@@ -3,6 +3,7 @@ import { z } from "zod";
 import { Env, FeedConfig, FeedMetadata, EmailData } from "../../types";
 import { generateFeedId } from "../../utils/id-generator";
 import { waitUntilSafe } from "../../utils/worker";
+import { feedRssUrl, feedEmailAddress } from "../../utils/urls";
 import { logger } from "../../lib/logger";
 import { Layout } from "./ui";
 import {
@@ -192,8 +193,6 @@ feedsRouter.post("/create", async (c) => {
       title: parsedData.title,
       description: parsedData.description,
       language: parsedData.language,
-      site_url: `https://${env.DOMAIN}/rss/${feedId}`,
-      feed_url: `https://${env.DOMAIN}/rss/${feedId}`,
       allowed_senders: parsedData.allowedSenders,
       created_at: Date.now(),
       updated_at: Date.now(),
@@ -216,8 +215,8 @@ feedsRouter.post("/create", async (c) => {
     if (isJson) {
       return c.json({
         feedId,
-        email: `${feedId}@${env.DOMAIN}`,
-        feedUrl: feedConfig.feed_url,
+        email: feedEmailAddress(feedId, env),
+        feedUrl: feedRssUrl(feedId, env),
       });
     }
 

src/routes/atom.test.ts

@@ -81,8 +81,6 @@ describe("Atom Feed Route", () => {
         JSON.stringify({
           title: "Atom Test Feed",
           description: "Integration test",
-          site_url: "https://test.getmynews.app/rss/test-feed-atom",
-          feed_url: "https://test.getmynews.app/rss/test-feed-atom",
           language: "en",
           created_at: 1700000000000,
         }),

src/routes/atom.ts

@@ -2,6 +2,7 @@ import { Context } from "hono";
 import { Env } from "../types";
 import { generateAtomFeed } from "../utils/feed-generator";
 import { fetchFeedData } from "../utils/feed-fetcher";
+import { baseUrl, feedAtomUrl } from "../utils/urls";
 
 export async function handle(c: Context<{ Bindings: Env }>): Promise<Response> {
   try {
@@ -10,23 +11,23 @@ export async function handle(c: Context<{ Bindings: Env }>): Promise<Response> {
       return new Response("Feed ID is required", { status: 400 });
     }
 
-    const feedData = await fetchFeedData(feedId, c.env, "atom");
+    const feedData = await fetchFeedData(feedId, c.env);
     if (!feedData) {
       return new Response("Feed not found", { status: 404 });
     }
 
-    const baseUrl = `https://${c.env.DOMAIN}`;
+    const base = baseUrl(c.env);
     const selfUrl = new URL(c.req.url).origin + `/atom/${feedId}`;
     const atomXml = generateAtomFeed(
       feedData.feedConfig,
       feedData.emails,
-      baseUrl,
+      base,
       feedId,
       selfUrl,
     );
     const linkHeader = [
-      `<${baseUrl}/hub>; rel="hub"`,
-      `<${baseUrl}/atom/${feedId}>; rel="self"`,
+      `<${base}/hub>; rel="hub"`,
+      `<${feedAtomUrl(feedId, c.env)}>; rel="self"`,
     ].join(", ");
 
     return new Response(atomXml, {

src/routes/hub.ts

@@ -6,6 +6,7 @@ import {
 } from "../utils/websub";
 import { waitUntilSafe } from "../utils/worker";
 import { DEFAULT_LEASE_SECONDS, MAX_LEASE_SECONDS } from "../config/constants";
+import { feedTopicPattern } from "../utils/urls";
 
 type AppEnv = { Bindings: Env };
 
@@ -60,9 +61,7 @@ hubRouter.post("/", async (c) => {
   }
 
   // Validate that topic matches a known RSS or Atom feed on this hub
-  const topicPattern = new RegExp(
-    `^https://${env.DOMAIN.replaceAll(".", "\\.")}/(rss|atom)/([^/]+)$`,
-  );
+  const topicPattern = feedTopicPattern(env);
   const match = topic.match(topicPattern);
   if (!match) {
     return c.text(

src/routes/rss.ts

@@ -2,6 +2,7 @@ import { Context } from "hono";
 import { Env } from "../types";
 import { generateRssFeed } from "../utils/feed-generator";
 import { fetchFeedData } from "../utils/feed-fetcher";
+import { baseUrl, feedRssUrl } from "../utils/urls";
 
 export async function handle(c: Context<{ Bindings: Env }>): Promise<Response> {
   try {
@@ -10,23 +11,23 @@ export async function handle(c: Context<{ Bindings: Env }>): Promise<Response> {
       return new Response("Feed ID is required", { status: 400 });
     }
 
-    const feedData = await fetchFeedData(feedId, c.env, "rss");
+    const feedData = await fetchFeedData(feedId, c.env);
     if (!feedData) {
       return new Response("Feed not found", { status: 404 });
     }
 
-    const baseUrl = `https://${c.env.DOMAIN}`;
+    const base = baseUrl(c.env);
     const selfUrl = new URL(c.req.url).origin + `/rss/${feedId}`;
     const rssXml = generateRssFeed(
       feedData.feedConfig,
       feedData.emails,
-      baseUrl,
+      base,
       feedId,
       selfUrl,
     );
     const linkHeader = [
-      `<${baseUrl}/hub>; rel="hub"`,
-      `<${baseUrl}/rss/${feedId}>; rel="self"`,
+      `<${base}/hub>; rel="hub"`,
+      `<${feedRssUrl(feedId, c.env)}>; rel="self"`,
     ].join(", ");
 
     return new Response(rssXml, {

src/types/index.ts

@@ -3,6 +3,7 @@ export interface Env {
   EMAIL_STORAGE: KVNamespace;
   ADMIN_PASSWORD: string;
   DOMAIN: string;
+  EMAIL_DOMAIN?: string;
   ATTACHMENT_BUCKET?: R2Bucket;
   FEED_MAX_SIZE_BYTES?: string;
   PROXY_TRUSTED_IPS?: string;
@@ -33,8 +34,6 @@ export interface FeedConfig {
   description?: string;
   allowed_senders?: string[];
   language: string;
-  site_url: string;
-  feed_url: string;
   author?: string;
   created_at: number;
   updated_at?: number;

src/utils/feed-fetcher.ts

@@ -9,7 +9,6 @@ export interface FeedData {
 export async function fetchFeedData(
   feedId: string,
   env: Env,
-  feedPath: "rss" | "atom",
 ): Promise<FeedData | null> {
   const storage = env.EMAIL_STORAGE;
 
@@ -26,8 +25,6 @@ export async function fetchFeedData(
   )) as FeedConfig | null) ?? {
     title: `Newsletter Feed ${feedId}`,
     description: "Converted email newsletter",
-    site_url: `https://${env.DOMAIN}/${feedPath}/${feedId}`,
-    feed_url: `https://${env.DOMAIN}/${feedPath}/${feedId}`,
     language: "en",
     created_at: Date.now(),
   };

src/utils/feed-generator.test.ts

@@ -9,8 +9,6 @@ import { FeedConfig, EmailData } from "../types";
 const mockFeedConfig: FeedConfig = {
   title: "Test Newsletter",
   description: "A test feed",
-  site_url: "https://test.getmynews.app/rss/abc123",
-  feed_url: "https://test.getmynews.app/rss/abc123",
   language: "en",
   created_at: 1700000000000,
 };

src/utils/urls.ts

@@ -0,0 +1,30 @@
+import { Env } from "../types";
+
+export function baseUrl(env: Env): string {
+  return `https://${env.DOMAIN}`;
+}
+
+export function feedRssUrl(feedId: string, env: Env): string {
+  return `${baseUrl(env)}/rss/${feedId}`;
+}
+
+export function feedAtomUrl(feedId: string, env: Env): string {
+  return `${baseUrl(env)}/atom/${feedId}`;
+}
+
+export function feedUrl(
+  format: "rss" | "atom",
+  feedId: string,
+  env: Env,
+): string {
+  return format === "rss" ? feedRssUrl(feedId, env) : feedAtomUrl(feedId, env);
+}
+
+export function feedEmailAddress(feedId: string, env: Env): string {
+  return `${feedId}@${env.EMAIL_DOMAIN ?? env.DOMAIN}`;
+}
+
+export function feedTopicPattern(env: Env): RegExp {
+  const escaped = env.DOMAIN.replaceAll(".", "\\.");
+  return new RegExp(`^https://${escaped}/(rss|atom)/([^/]+)$`);
+}

src/utils/websub.test.ts

@@ -101,8 +101,6 @@ describe("notifySubscribers", () => {
       JSON.stringify({
         title: "Test Feed",
         language: "en",
-        site_url: "https://example.com",
-        feed_url: "https://example.com/rss/feed1",
         created_at: Date.now(),
       }),
     );
@@ -141,8 +139,6 @@ describe("notifySubscribers", () => {
       JSON.stringify({
         title: "Test Feed",
         language: "en",
-        site_url: "https://example.com",
-        feed_url: "https://example.com/rss/feed1",
         created_at: Date.now(),
       }),
     );
@@ -181,8 +177,6 @@ describe("notifySubscribers", () => {
       JSON.stringify({
         title: "Test Feed",
         language: "en",
-        site_url: "https://example.com",
-        feed_url: "https://example.com/rss/feed1",
         created_at: Date.now(),
       }),
     );
@@ -222,8 +216,6 @@ describe("notifySubscribers", () => {
       JSON.stringify({
         title: "Test Feed",
         language: "en",
-        site_url: "https://example.com",
-        feed_url: "https://example.com/rss/feed1",
         created_at: Date.now(),
       }),
     );
@@ -269,8 +261,6 @@ describe("notifySubscribers", () => {
       JSON.stringify({
         title: "Test Feed",
         language: "en",
-        site_url: "https://example.com",
-        feed_url: "https://example.com/rss/feed1",
         created_at: Date.now(),
       }),
     );

src/utils/websub.ts

@@ -6,6 +6,7 @@ import {
   WebSubSubscription,
 } from "../types";
 import { generateRssFeed, generateAtomFeed } from "./feed-generator";
+import { baseUrl, feedRssUrl, feedAtomUrl, feedUrl } from "./urls";
 
 const KV_PREFIX = "websub:subs:";
 
@@ -67,12 +68,10 @@ async function buildFeedXml(
   const feedMetadata = rawMetadata as FeedMetadata | null;
   if (!feedMetadata) return null;
 
-  const baseUrl = `https://${env.DOMAIN}`;
+  const base = baseUrl(env);
   const feedConfig = (rawConfig as FeedConfig | null) ?? {
     title: `Newsletter Feed ${feedId}`,
     description: "Converted email newsletter",
-    site_url: `${baseUrl}/rss/${feedId}`,
-    feed_url: `${baseUrl}/rss/${feedId}`,
     language: "en",
     created_at: Date.now(),
   };
@@ -91,12 +90,12 @@ async function buildFeedXml(
     return generateAtomFeed(
       feedConfig,
       emailsData,
-      baseUrl,
+      base,
       feedId,
-      `${baseUrl}/atom/${feedId}`,
+      feedAtomUrl(feedId, env),
     );
   }
-  return generateRssFeed(feedConfig, emailsData, baseUrl, feedId);
+  return generateRssFeed(feedConfig, emailsData, base, feedId);
 }
 
 export async function notifySubscribers(
@@ -124,7 +123,7 @@ export async function notifySubscribers(
 
   if (!rssFeed && !atomFeed) return;
 
-  const baseUrl = `https://${env.DOMAIN}`;
+  const base = baseUrl(env);
 
   const deliver = async (
     sub: WebSubSubscription,
@@ -132,7 +131,7 @@ export async function notifySubscribers(
     contentType: string,
     selfPath: string,
   ) => {
-    const linkHeader = `<${baseUrl}/hub>; rel="hub", <${baseUrl}${selfPath}>; rel="self"`;
+    const linkHeader = `<${base}/hub>; rel="hub", <${base}${selfPath}>; rel="self"`;
     const headers: Record<string, string> = {
       "Content-Type": contentType,
       Link: linkHeader,
@@ -173,6 +172,26 @@ export async function notifySubscribers(
   }
 }
 
+async function verifyCallback(
+  callbackUrl: string,
+  params: Record<string, string>,
+): Promise<boolean> {
+  const challenge = crypto.randomUUID().replace(/-/g, "");
+  const url = new URL(callbackUrl);
+  for (const [k, v] of Object.entries(params)) url.searchParams.set(k, v);
+  url.searchParams.set("hub.challenge", challenge);
+
+  let res: Response;
+  try {
+    res = await fetch(url.toString());
+  } catch {
+    return false;
+  }
+
+  if (!res.ok) return false;
+  return (await res.text()).trim() === challenge;
+}
+
 export async function verifyAndStoreSubscription(
   feedId: string,
   callbackUrl: string,
@@ -181,24 +200,12 @@ export async function verifyAndStoreSubscription(
   format: "rss" | "atom",
   env: Env,
 ): Promise<boolean> {
-  const challenge = crypto.randomUUID().replace(/-/g, "");
-  const topicUrl = `https://${env.DOMAIN}/${format}/${feedId}`;
-  const verifyUrl = new URL(callbackUrl);
-  verifyUrl.searchParams.set("hub.mode", "subscribe");
-  verifyUrl.searchParams.set("hub.topic", topicUrl);
-  verifyUrl.searchParams.set("hub.challenge", challenge);
-  verifyUrl.searchParams.set("hub.lease_seconds", String(leaseSeconds));
-
-  let res: Response;
-  try {
-    res = await fetch(verifyUrl.toString());
-  } catch {
-    return false;
-  }
-
-  if (!res.ok) return false;
-  const body = await res.text();
-  if (body.trim() !== challenge) return false;
+  const verified = await verifyCallback(callbackUrl, {
+    "hub.mode": "subscribe",
+    "hub.topic": feedUrl(format, feedId, env),
+    "hub.lease_seconds": String(leaseSeconds),
+  });
+  if (!verified) return false;
 
   const subs = await getSubscriptions(feedId, env);
   const idx = subs.findIndex((s) => s.callbackUrl === callbackUrl);
@@ -222,23 +229,11 @@ export async function verifyAndDeleteSubscription(
   callbackUrl: string,
   env: Env,
 ): Promise<boolean> {
-  const challenge = crypto.randomUUID().replace(/-/g, "");
-  const topicUrl = `https://${env.DOMAIN}/rss/${feedId}`;
-  const verifyUrl = new URL(callbackUrl);
-  verifyUrl.searchParams.set("hub.mode", "unsubscribe");
-  verifyUrl.searchParams.set("hub.topic", topicUrl);
-  verifyUrl.searchParams.set("hub.challenge", challenge);
-
-  let res: Response;
-  try {
-    res = await fetch(verifyUrl.toString());
-  } catch {
-    return false;
-  }
-
-  if (!res.ok) return false;
-  const body = await res.text();
-  if (body.trim() !== challenge) return false;
+  const verified = await verifyCallback(callbackUrl, {
+    "hub.mode": "unsubscribe",
+    "hub.topic": feedRssUrl(feedId, env),
+  });
+  if (!verified) return false;
 
   const subs = await getSubscriptions(feedId, env);
   await saveSubscriptions(