Add feed discovery plugin

plugins/feed-discovery/src/output/atom.ts

@@ -0,0 +1,26 @@
+import type { FeedDiscoveryResponse } from "../types.js";
+import { escapeXml } from "./opml.js";
+
+export function renderAtom(response: FeedDiscoveryResponse) {
+  const updated = new Date().toISOString();
+  const entries = response.results
+    .map((result) => {
+      const id = result.canonicalFeedUrl ?? result.feedUrl;
+      return `  <entry>
+    <id>${escapeXml(id)}</id>
+    <title>${escapeXml(result.title)}</title>
+    <link href="${escapeXml(result.homepageUrl ?? result.feedUrl)}" />
+    <updated>${escapeXml(result.lastPublishedAt ?? updated)}</updated>
+    <summary>${escapeXml(result.description ?? `Discovered ${result.kind} feed from ${result.provider}`)}</summary>
+  </entry>`;
+    })
+    .join("\n");
+
+  return `<?xml version="1.0" encoding="UTF-8"?>
+<feed xmlns="http://www.w3.org/2005/Atom">
+  <id>logicsrc:feed-discovery:${escapeXml(response.normalizedQuery)}</id>
+  <title>LogicSRC feed discovery: ${escapeXml(response.query)}</title>
+  <updated>${updated}</updated>
+${entries}
+</feed>`;
+}