Discovery anchors and top tags (BL-0051)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

discovery/anchors.js

@@ -0,0 +1,63 @@
+'use strict';
+
+// Anchors are the titles a user has shown taste for; their tags steer the wider AniList pool.
+const ANCHOR_WEIGHTS = { flame: 5, good: 3, interested: 4, maybe: 2, read: 3, owned: 1 };
+const MAX_ANCHORS = 15;
+const MIN_TAG_RANK = 60;
+const MAX_TOP_TAGS = 3;
+
+function anchorsFor({ user, db, library, greatest }) {
+  if (!user?.settings?.discoveryEnabled) return [];
+  const byId = new Map();
+  const add = (anilistId, source, title) => {
+    if (!Number.isSafeInteger(anilistId) || anilistId <= 0) return;
+    const weight = ANCHOR_WEIGHTS[source];
+    const prior = byId.get(anilistId);
+    if (!prior || weight > prior.weight) byId.set(anilistId, { anilistId, weight, source, title: title ?? null });
+  };
+
+  const ratings = db?.greatestRatings?.[user.name] || {};
+  for (const entry of greatest?.entries || []) {
+    const vote = ratings[entry.id];
+    if (vote === 'flame' || vote === 'good') add(Number(entry.metadata?.id), vote, entry.title);
+  }
+
+  const feedback = db?.discoveryFeedback?.[user.name] || {};
+  for (const [key, value] of Object.entries(feedback)) {
+    const match = /^anilist:(\d+)$/.exec(key);
+    if (match && (value === 'interested' || value === 'maybe')) add(Number(match[1]), value, null);
+  }
+
+  const progress = db?.progress?.[user.name] || {};
+  const reading = Boolean(user.settings.discoveryReadingActivity);
+  for (const manga of library || []) {
+    const id = Number(manga.meta?.['x-anilist']?.id);
+    if (!id) continue;
+    const chapters = progress[manga.id];
+    const done = reading && chapters && Object.values(chapters).some(chapter => chapter?.done);
+    add(id, done ? 'read' : 'owned', manga.title);
+  }
+
+  return [...byId.values()]
+    .sort((a, b) => b.weight - a.weight || a.anilistId - b.anilistId)
+    .slice(0, MAX_ANCHORS);
+}
+
+function topTagsFor(anchors, recordOf, { mature = false } = {}) {
+  const scores = new Map();
+  for (const anchor of anchors) {
+    const record = recordOf(anchor.anilistId);
+    for (const tag of record?.tags || []) {
+      if (tag.rank < MIN_TAG_RANK || (tag.isAdult && !mature)) continue;
+      const entry = scores.get(tag.name) || { name: tag.name, kind: tag.kind, score: 0 };
+      entry.score += anchor.weight;
+      scores.set(tag.name, entry);
+    }
+  }
+  return [...scores.values()]
+    .sort((a, b) => b.score - a.score || (a.name < b.name ? -1 : a.name > b.name ? 1 : 0))
+    .slice(0, MAX_TOP_TAGS)
+    .map(({ name, kind }) => ({ name, kind }));
+}
+
+module.exports = { ANCHOR_WEIGHTS, MAX_ANCHORS, anchorsFor, topTagsFor };