fix: improve fediverse detection and feed discovery

- fetcher.js: try <link rel="alternate"> HTML discovery before
  falling back to common feed paths (/feed, /rss.xml, etc.), fixing
  subscriptions to sites like Substack, econsoc.mpifg.de, and others
  whose feed URL is advertised via a link element but not at a
  predictable path

- reader.js: extend detectProtocol to recognise more fediverse
  domains (troet., social., hachyderm., infosec.exchange, chaos.social)

- reader.js: don't auto-check Mastodon syndication target for likes
  and reposts — those are handled natively by the AP endpoint; use
  service-name-aware target matching that works for any configured
  Mastodon instance even if its domain isn't in the hardcoded list

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

lib/controllers/reader.js

@@ -446,8 +446,11 @@ function detectProtocol(url) {
   if (!url || typeof url !== "string") return "web";
   const lower = url.toLowerCase();
   if (lower.includes("bsky.app") || lower.includes("bluesky")) return "atmosphere";
+  // Well-known fediverse software domain patterns
   if (lower.includes("mastodon.") || lower.includes("mstdn.") || lower.includes("fosstodon.") ||
-      lower.includes("pleroma.") || lower.includes("misskey.") || lower.includes("pixelfed.")) return "fediverse";
+      lower.includes("troet.") || lower.includes("social.") || lower.includes("pleroma.") ||
+      lower.includes("misskey.") || lower.includes("pixelfed.") || lower.includes("hachyderm.") ||
+      lower.includes("infosec.exchange") || lower.includes("chaos.social")) return "fediverse";
   return "web";
 }
 
@@ -510,15 +513,36 @@ export async function compose(request, response) {
     ? await getSyndicationTargets(application, token)
     : [];
 
-  // Auto-select syndication target based on interaction URL protocol
+  // Auto-select syndication target based on interaction URL protocol.
+  // Likes and reposts on fediverse are handled natively by the AP endpoint —
+  // never auto-check Mastodon for those action types.
+  const isLikeOrRepost = !!(likeOf || like || repostOf || repost);
   const interactionUrl = ensureString(replyTo || reply || likeOf || like || repostOf || repost);
-  if (interactionUrl && syndicationTargets.length > 0) {
+  if (interactionUrl && syndicationTargets.length > 0 && !isLikeOrRepost) {
     const protocol = detectProtocol(interactionUrl);
+
+    // Build set of Mastodon instance hostnames from configured targets so we
+    // can match same-instance URLs even if not in the hardcoded pattern list.
+    const mastodonHostnames = new Set();
+    for (const t of syndicationTargets) {
+      if (t.service?.name?.toLowerCase() === "mastodon" && t.service?.url) {
+        try { mastodonHostnames.add(new URL(t.service.url).hostname.toLowerCase()); } catch { /* ignore */ }
+      }
+    }
+    let interactionHostname = "";
+    try { interactionHostname = new URL(interactionUrl).hostname.toLowerCase(); } catch { /* ignore */ }
+
     for (const target of syndicationTargets) {
       const targetId = (target.uid || target.name || "").toLowerCase();
+      // Identify a Mastodon target by service name (reliable) or legacy uid/name patterns
+      const isMastodonTarget =
+        target.service?.name?.toLowerCase() === "mastodon" ||
+        targetId.includes("mastodon") ||
+        targetId.includes("mstdn");
+
       if (protocol === "atmosphere" && (targetId.includes("bluesky") || targetId.includes("bsky"))) {
         target.checked = true;
-      } else if (protocol === "fediverse" && (targetId.includes("mastodon") || targetId.includes("mstdn"))) {
+      } else if (isMastodonTarget && (protocol === "fediverse" || mastodonHostnames.has(interactionHostname))) {
         target.checked = true;
       }
     }

lib/feeds/fetcher.js

@@ -164,9 +164,24 @@ export async function fetchAndParseFeed(url, options = {}) {
   // Check if we got a parseable feed
   const feedType = detectFeedType(result.content, result.contentType);
 
-  // If we got ActivityPub or unknown, try common feed paths
+  // If we got ActivityPub or unknown, try link-based discovery then common paths
   if (feedType === "activitypub" || feedType === "unknown") {
-    const fallbackFeed = await tryCommonFeedPaths(url, options);
+    // 1. link-based discovery from HTML: parse <link rel="alternate" type="application/rss+xml|atom+xml">
+    let discoveredFeedUrl;
+    if (result.content) {
+      const { discoverFeeds } = await import("./hfeed.js");
+      const discovered = await discoverFeeds(result.content, url);
+      const rssOrAtom = discovered.find(
+        (f) => f.type === "rss" || f.type === "atom" || f.type === "jsonfeed",
+      );
+      if (rssOrAtom) discoveredFeedUrl = rssOrAtom.url;
+    }
+
+    // 2. Fall back to common feed paths (/feed, /rss.xml, etc.)
+    const fallbackFeed = discoveredFeedUrl
+      ? { url: discoveredFeedUrl }
+      : await tryCommonFeedPaths(url, options);
+
     if (fallbackFeed) {
       // Fetch and parse the discovered feed
       const feedResult = await fetchFeed(fallbackFeed.url, options);