fix(search): surface iTunes stubs and resolve feeds for delisted shows

Shows that left Apple Podcasts (e.g. Daily Wire's in 2021) come back from
the iTunes Search API as metadata-only stub records with feedUrl null.
mapItunesResult dropped them, so The Ben Shapiro Show — the #1 hit for
'ben shapiro' — never appeared in search while sibling shows did.

- Keep feedUrl-less results (feedUrl "" + directoryUrl pointing at the
  Apple page) so delisted shows stay findable.
- Resolve the real feed from the Apple page at subscribe time
  (itunes-feed-resolver: anchor on the collection's adamId, forward-scan
  for the embedded feedUrl; Apple serves page variants where the
  showOffer block sits thousands of chars after the adamId).
- addFeed refuses feedless stubs whose feed can't be resolved instead of
  adding a broken feed; SearchPage surfaces the failure via toast.
- Tests: stub mapping, extractor variants, and an end-to-end subscribe
  over a local HTTP server.

src/utils/itunes-feed-resolver.ts

@@ -0,0 +1,61 @@
+/**
+ * iTunes feed resolution for shows delisted from Apple Podcasts.
+ *
+ * The iTunes Search API returns `feedUrl: null` for shows that left Apple
+ * Podcasts (e.g. The Daily Wire's shows in 2021) — the directory keeps a
+ * metadata-only stub. The show's public Apple Podcasts page still embeds the
+ * real feed URL in its JSON state (`showOffer.feedUrl`), so subscribing can
+ * resolve it from there.
+ */
+
+/** `"feedUrl":"https://..."` as embedded in the Apple page's JSON state. */
+const FEED_URL_RE = /"feedUrl"\s*:\s*"(https?:\/\/[^"]+)"/
+
+/**
+ * Extract the show's feed URL from an Apple Podcasts page's HTML.
+ *
+ * The page embeds `showOffer` blocks for the show AND for related shows, each
+ * with its own feedUrl, and Apple serves multiple JSON variants — the main
+ * show's showOffer may sit adjacent to its adamId or thousands of chars later.
+ * Anchor on the collection id from `directoryUrl` (`"adamId":"<id>"`) and take
+ * the FIRST feedUrl after it (the main show's content precedes related shows'
+ * in the document). Falls back to the first feedUrl in the document only when
+ * the id isn't present in the URL. Returns null when no trustworthy match
+ * exists (page restructured, no feed) — callers must not guess.
+ */
+export const extractFeedUrlFromPage = (
+  html: string,
+  directoryUrl: string,
+): string | null => {
+  const idMatch = /[?/]id(\d+)/.exec(directoryUrl)
+  if (!idMatch) {
+    const fallback = FEED_URL_RE.exec(html)
+    return fallback ? fallback[1] : null
+  }
+
+  const adamIdx = html.search(new RegExp(`"adamId"\\s*:\\s*"${idMatch[1]}"`))
+  if (adamIdx < 0) return null
+
+  const fromAdam = new RegExp(FEED_URL_RE.source, "g")
+  fromAdam.lastIndex = adamIdx
+  const match = fromAdam.exec(html)
+  return match ? match[1] : null
+}
+
+/**
+ * Resolve a delisted show's RSS feed from its Apple Podcasts page.
+ * Returns null on network failure or when the page has no resolvable feed.
+ */
+export const resolveItunesFeedUrl = async (
+  directoryUrl: string,
+): Promise<string | null> => {
+  try {
+    const response = await fetch(directoryUrl, {
+      headers: { "User-Agent": "PodTUI/1.0" },
+    })
+    if (!response.ok) return null
+    return extractFeedUrlFromPage(await response.text(), directoryUrl)
+  } catch {
+    return null
+  }
+}

src/utils/source-searcher.ts

@@ -14,11 +14,13 @@ type ItunesResult = {
   collectionId?: number
   collectionName?: string
   artistName?: string
-  feedUrl?: string
+  /** Null for shows delisted from Apple Podcasts (directory stub records). */
+  feedUrl?: string | null
   artworkUrl100?: string
   artworkUrl600?: string
   primaryGenreName?: string
   releaseDate?: string
+  collectionViewUrl?: string
 }
 
 type ItunesResponse = {
@@ -41,8 +43,8 @@ const buildItunesUrl = (query: string, source: PodcastSource) => {
   return url.toString()
 }
 
-const mapItunesResult = (result: ItunesResult, source: PodcastSource): Podcast | null => {
-  if (!result.collectionName || !result.feedUrl) return null
+export const mapItunesResult = (result: ItunesResult, source: PodcastSource): Podcast | null => {
+  if (!result.collectionName) return null
 
   const id = result.collectionId
     ? `itunes-${result.collectionId}`
@@ -52,11 +54,18 @@ const mapItunesResult = (result: ItunesResult, source: PodcastSource): Podcast |
   if (result.artistName) descriptionParts.push(`by ${result.artistName}`)
   if (result.primaryGenreName) descriptionParts.push(result.primaryGenreName)
 
+  // Shows delisted from Apple Podcasts (e.g. The Daily Wire's shows) come back
+  // as metadata-only stub records with feedUrl null. Keep the stub so the show
+  // stays findable; the real feed is resolved from the directory page at
+  // subscribe time (see itunes-feed-resolver).
+  const feedUrl = result.feedUrl ?? ""
+
   return {
     id,
     title: result.collectionName,
     description: descriptionParts.join(" • "),
-    feedUrl: result.feedUrl,
+    feedUrl,
+    directoryUrl: feedUrl ? undefined : result.collectionViewUrl,
     author: result.artistName,
     categories: result.primaryGenreName ? [result.primaryGenreName] : undefined,
     coverUrl: result.artworkUrl600 || result.artworkUrl100,