Resolve YouTube @handles and vanity URLs to a channel ID automatically

YouTube's public Atom feed only accepts a channel_id (or the legacy user
param) — it has no equivalent for the newer @handle format, so pasting a
handle URL straight into the source's url field wouldn't have worked. The
adapter now accepts a bare channel ID, a /channel/UC... URL, an @handle URL,
or a bare handle/username, resolving whichever was given to the actual
channel ID by reading it off the channel page when needed.

backend/src/ingestion/adapters/youtube.ts

@@ -24,14 +24,63 @@ const parser = new Parser<Record<string, unknown>, YoutubeEntry>({
 	}
 });
 
-/** Builds the channel's Atom feed URL — YouTube publishes these publicly with no API key required. */
-function feedUrl(source: Source): string | null {
-	if (source.url) return source.url;
+const USER_AGENT = 'Mozilla/5.0 (compatible; HomefeedBot/1.0; self-hosted RSS reader)';
+const CHANNEL_ID_RE = /^UC[\w-]{22}$/;
+
+/**
+ * Resolves whatever the admin typed into the source's URL field into the channel's
+ * Atom feed URL. YouTube's public feed endpoint (no API key needed) only accepts a
+ * `channel_id` (the UC... hash) or the legacy `user` parameter — it has no equivalent
+ * for the newer `@handle` format, so a handle (or a /c/ or /user/ vanity URL) has to be
+ * resolved to its real channel ID first by fetching the channel page and pulling the
+ * ID out of it.
+ */
+async function resolveFeedUrl(source: Source): Promise<string | null> {
 	const channelId = source.config?.channelId as string | undefined;
 	if (channelId) return `https://www.youtube.com/feeds/videos.xml?channel_id=${encodeURIComponent(channelId)}`;
+
 	const playlistId = source.config?.playlistId as string | undefined;
 	if (playlistId) return `https://www.youtube.com/feeds/videos.xml?playlist_id=${encodeURIComponent(playlistId)}`;
-	return null;
+
+	const raw = source.url?.trim();
+	if (!raw) return null;
+
+	if (raw.includes('feeds/videos.xml')) return raw;
+	if (CHANNEL_ID_RE.test(raw)) return `https://www.youtube.com/feeds/videos.xml?channel_id=${raw}`;
+
+	const idInUrl = raw.match(/\/channel\/(UC[\w-]{22})/);
+	if (idInUrl) return `https://www.youtube.com/feeds/videos.xml?channel_id=${idInUrl[1]}`;
+
+	let pageUrl: string;
+	if (/^https?:\/\//i.test(raw)) {
+		pageUrl = raw;
+	} else if (/youtube\.com|youtu\.be/i.test(raw)) {
+		pageUrl = `https://${raw}`;
+	} else {
+		// A bare handle or legacy username typed on its own, e.g. "PsyopAnime" or "@PsyopAnime".
+		pageUrl = `https://www.youtube.com/@${raw.replace(/^@/, '')}`;
+	}
+
+	const resolvedId = await resolveChannelIdFromPage(pageUrl);
+	if (!resolvedId) {
+		logger.warn('youtube', `Couldn't resolve a channel ID from "${raw}" — double-check the handle/URL`);
+		return null;
+	}
+	return `https://www.youtube.com/feeds/videos.xml?channel_id=${resolvedId}`;
+}
+
+/** Every YouTube channel page embeds its own canonical channel ID — pulled from either the canonical link tag or the page's inline JSON. */
+async function resolveChannelIdFromPage(url: string): Promise<string | null> {
+	try {
+		const res = await fetch(url, { headers: { 'User-Agent': USER_AGENT }, signal: AbortSignal.timeout(10_000) });
+		if (!res.ok) return null;
+		const html = await res.text();
+		const match = html.match(/"channelId":"(UC[\w-]{22})"/) || html.match(/\/channel\/(UC[\w-]{22})/);
+		return match ? match[1] : null;
+	} catch (err) {
+		logger.warn('youtube', `Channel page fetch failed for ${url}: ${(err as Error).message}`);
+		return null;
+	}
 }
 
 function extractVideoId(url: string): string | null {
@@ -52,9 +101,9 @@ function extractThumbnail(item: YoutubeEntry): string | null {
 
 export const youtubeAdapter: SourceAdapter = {
 	async fetch(source: Source): Promise<FetchedItem[]> {
-		const url = feedUrl(source);
+		const url = await resolveFeedUrl(source);
 		if (!url) {
-			logger.warn('youtube', `Source "${source.name}" has no url, channelId, or playlistId configured — skipping`);
+			logger.warn('youtube', `Source "${source.name}" has no usable url, channelId, or playlistId configured — skipping`);
 			return [];
 		}
 

frontend/src/lib/components/admin/SourcesTab.svelte

@@ -157,7 +157,7 @@
 				<option value="custom">Custom</option>
 			</select>
 			{#if form.type === 'youtube'}
-				<input placeholder="Channel ID, playlist ID, or full feed URL" bind:value={form.channelId} />
+				<input placeholder="Channel URL (@handle or /channel/UC…), or channel ID" bind:value={form.channelId} />
 			{:else}
 				<input placeholder="URL or channel" bind:value={form.url} />
 			{/if}