feat: cache remote account stats for embedded status accounts

Phanpy never calls /accounts/:id for timeline authors — it uses the
embedded account object from the status response. These had 0 counts
because the timeline author data doesn't include follower stats.

Fix: in-memory LRU cache (500 entries, 1h TTL) stores account stats
from remote resolutions. serializeAccount() reads from cache when
the actor has 0 counts, enriching embedded accounts with real data.

Cache is populated by resolveRemoteAccount() (lookup, search, and
/accounts/:id calls). Once a profile has been viewed once, all
subsequent status embeds for that author show real counts.

lib/mastodon/entities/account.js

@@ -7,6 +7,7 @@
  */
 import { accountId } from "../helpers/id-mapping.js";
 import { sanitizeHtml, stripHtml } from "./sanitize.js";
+import { getCachedAccountStats } from "../helpers/account-cache.js";
 
 /**
  * Serialize an actor as a Mastodon Account entity.
@@ -111,6 +112,20 @@ export function serializeAccount(actor, { baseUrl, isLocal = false, handle = ""
     statuses_count: actor.statusesCount || 0,
     followers_count: actor.followersCount || 0,
     following_count: actor.followingCount || 0,
+    // Enrich from cache if counts are 0 (embedded accounts in statuses lack counts)
+    ...((!actor.statusesCount && !actor.followersCount && !isLocal)
+      ? (() => {
+          const cached = getCachedAccountStats(url);
+          return cached
+            ? {
+                statuses_count: cached.statusesCount || 0,
+                followers_count: cached.followersCount || 0,
+                following_count: cached.followingCount || 0,
+                created_at: cached.createdAt || actor.createdAt || new Date().toISOString(),
+              }
+            : {};
+        })()
+      : {}),
     moved: actor.movedTo || null,
     suspended: false,
     limited: false,

lib/mastodon/helpers/account-cache.js

@@ -0,0 +1,51 @@
+/**
+ * In-memory cache for remote account stats (followers, following, statuses).
+ *
+ * Populated by resolveRemoteAccount() when a profile is fetched.
+ * Read by serializeAccount() to enrich embedded account objects in statuses.
+ *
+ * LRU-style with TTL — entries expire after 1 hour.
+ */
+
+const CACHE_TTL_MS = 60 * 60 * 1000; // 1 hour
+const MAX_ENTRIES = 500;
+
+// Map<actorUrl, { followersCount, followingCount, statusesCount, createdAt, cachedAt }>
+const cache = new Map();
+
+/**
+ * Store account stats in cache.
+ * @param {string} actorUrl - The actor's URL (cache key)
+ * @param {object} stats - { followersCount, followingCount, statusesCount, createdAt }
+ */
+export function cacheAccountStats(actorUrl, stats) {
+  if (!actorUrl) return;
+
+  // Evict oldest if at capacity
+  if (cache.size >= MAX_ENTRIES) {
+    const oldest = cache.keys().next().value;
+    cache.delete(oldest);
+  }
+
+  cache.set(actorUrl, { ...stats, cachedAt: Date.now() });
+}
+
+/**
+ * Get cached account stats.
+ * @param {string} actorUrl - The actor's URL
+ * @returns {object|null} Stats or null if not cached/expired
+ */
+export function getCachedAccountStats(actorUrl) {
+  if (!actorUrl) return null;
+
+  const entry = cache.get(actorUrl);
+  if (!entry) return null;
+
+  // Check TTL
+  if (Date.now() - entry.cachedAt > CACHE_TTL_MS) {
+    cache.delete(actorUrl);
+    return null;
+  }
+
+  return entry;
+}

lib/mastodon/helpers/resolve-account.js

@@ -5,6 +5,7 @@
  * Shared by accounts.js (lookup) and search.js (resolve=true).
  */
 import { serializeAccount } from "../entities/account.js";
+import { cacheAccountStats } from "./account-cache.js";
 
 /**
  * @param {string} acct - Account identifier (user@domain or URL)
@@ -115,6 +116,14 @@ export async function resolveRemoteAccount(acct, pluginOptions, baseUrl) {
     account.following_count = followingCount;
     account.statuses_count = statusesCount;
 
+    // Cache stats so embedded account objects in statuses can use them
+    cacheAccountStats(actorUrl, {
+      followersCount,
+      followingCount,
+      statusesCount,
+      createdAt: published || undefined,
+    });
+
     return account;
   } catch (error) {
     console.warn(`[Mastodon API] Remote account resolution failed for ${acct}:`, error.message);