perf(api,frontend): index hot queries, paginate chats, fix realtime

frontend/src/lib/api/avatars.ts

@@ -6,6 +6,8 @@ const RETRY_DELAY = 2500;
 
 export type AvatarKind = "peer" | "chat";
 
+const MAX_CACHED = 240;
+
 const ready = new Map<string, string>();
 const missing = new Set<string>();
 const inflight = new Map<string, Promise<string | null>>();
@@ -14,6 +16,21 @@ function cacheKey(account: number, kind: AvatarKind, id: number): string {
   return `${account}:${kind}:${id}`;
 }
 
+function remember(key: string, url: string) {
+  ready.set(key, url);
+  while (ready.size > MAX_CACHED) {
+    const oldest = ready.keys().next();
+    if (oldest.done) {
+      return;
+    }
+    const stale = ready.get(oldest.value);
+    ready.delete(oldest.value);
+    if (stale) {
+      URL.revokeObjectURL(stale);
+    }
+  }
+}
+
 function authHeaders(): Record<string, string> {
   return auth.token ? { Authorization: `Bearer ${auth.token}` } : {};
 }
@@ -35,7 +52,7 @@ async function fetchAvatar(
   const response = await fetch(url, { headers: authHeaders() });
   if (response.ok) {
     const objectUrl = URL.createObjectURL(await response.blob());
-    ready.set(key, objectUrl);
+    remember(key, objectUrl);
     return objectUrl;
   }
   if (response.status === 409 && retry) {
@@ -85,7 +102,7 @@ async function fetchVariant(
   const response = await fetch(url, { headers: authHeaders() });
   if (response.ok) {
     const objectUrl = URL.createObjectURL(await response.blob());
-    ready.set(key, objectUrl);
+    remember(key, objectUrl);
     return objectUrl;
   }
   if (response.status === 409 && retry) {