feat: 1-to-1 message render + web data-lake backend

frontend/src/lib/api/avatars.ts

@@ -0,0 +1,74 @@
+import { accounts } from "$lib/stores/accounts.svelte";
+import { auth } from "$lib/stores/auth.svelte";
+
+const BASE = import.meta.env.VITE_API_BASE ?? "/api";
+const RETRY_DELAY = 2500;
+
+export type AvatarKind = "peer" | "chat";
+
+const ready = new Map<string, string>();
+const missing = new Set<string>();
+const inflight = new Map<string, Promise<string | null>>();
+
+function cacheKey(account: number, kind: AvatarKind, id: number): string {
+  return `${account}:${kind}:${id}`;
+}
+
+function authHeaders(): Record<string, string> {
+  return auth.token ? { Authorization: `Bearer ${auth.token}` } : {};
+}
+
+function delay(ms: number): Promise<void> {
+  return new Promise((resolve) => {
+    setTimeout(resolve, ms);
+  });
+}
+
+async function fetchAvatar(
+  account: number,
+  kind: AvatarKind,
+  id: number,
+  key: string,
+  retry: boolean
+): Promise<string | null> {
+  const url = `${BASE}/avatars/${kind}/${id}?account_id=${account}`;
+  const response = await fetch(url, { headers: authHeaders() });
+  if (response.ok) {
+    const objectUrl = URL.createObjectURL(await response.blob());
+    ready.set(key, objectUrl);
+    return objectUrl;
+  }
+  if (response.status === 409 && retry) {
+    await delay(RETRY_DELAY);
+    return fetchAvatar(account, kind, id, key, false);
+  }
+  missing.add(key);
+  return null;
+}
+
+export function loadAvatar(
+  kind: AvatarKind,
+  id: number
+): Promise<string | null> {
+  const account = accounts.selectedId;
+  if (account === null) {
+    return Promise.resolve(null);
+  }
+  const key = cacheKey(account, kind, id);
+  const cached = ready.get(key);
+  if (cached) {
+    return Promise.resolve(cached);
+  }
+  if (missing.has(key)) {
+    return Promise.resolve(null);
+  }
+  const existing = inflight.get(key);
+  if (existing) {
+    return existing;
+  }
+  const promise = fetchAvatar(account, kind, id, key, true).finally(() => {
+    inflight.delete(key);
+  });
+  inflight.set(key, promise);
+  return promise;
+}