feat: Only show available models in selector (#238)

src/agent/available-models.ts

@@ -0,0 +1,101 @@
+import { getClient } from "./client";
+
+const CACHE_TTL_MS = 5 * 60 * 1000; // 5 minutes
+
+type CacheEntry = {
+  handles: Set<string>;
+  fetchedAt: number;
+};
+
+let cache: CacheEntry | null = null;
+let inflight: Promise<CacheEntry> | null = null;
+
+function isFresh(now = Date.now()) {
+  return cache !== null && now - cache.fetchedAt < CACHE_TTL_MS;
+}
+
+export type AvailableModelHandlesResult = {
+  handles: Set<string>;
+  source: "cache" | "network";
+  fetchedAt: number;
+};
+
+export function clearAvailableModelsCache() {
+  cache = null;
+}
+
+export function getAvailableModelsCacheInfo(): {
+  hasCache: boolean;
+  isFresh: boolean;
+  fetchedAt: number | null;
+  ageMs: number | null;
+  ttlMs: number;
+} {
+  const now = Date.now();
+  return {
+    hasCache: cache !== null,
+    isFresh: isFresh(now),
+    fetchedAt: cache?.fetchedAt ?? null,
+    ageMs: cache ? now - cache.fetchedAt : null,
+    ttlMs: CACHE_TTL_MS,
+  };
+}
+
+async function fetchFromNetwork(): Promise<CacheEntry> {
+  const client = await getClient();
+  const modelsList = await client.models.list();
+  const handles = new Set(
+    modelsList.map((m) => m.handle).filter((h): h is string => !!h),
+  );
+  return { handles, fetchedAt: Date.now() };
+}
+
+export async function getAvailableModelHandles(options?: {
+  forceRefresh?: boolean;
+}): Promise<AvailableModelHandlesResult> {
+  const forceRefresh = options?.forceRefresh === true;
+  const now = Date.now();
+
+  if (!forceRefresh && isFresh(now) && cache) {
+    return {
+      handles: cache.handles,
+      source: "cache",
+      fetchedAt: cache.fetchedAt,
+    };
+  }
+
+  if (!forceRefresh && inflight) {
+    const entry = await inflight;
+    return {
+      handles: entry.handles,
+      source: "network",
+      fetchedAt: entry.fetchedAt,
+    };
+  }
+
+  inflight = fetchFromNetwork()
+    .then((entry) => {
+      cache = entry;
+      return entry;
+    })
+    .finally(() => {
+      inflight = null;
+    });
+
+  const entry = await inflight;
+  return {
+    handles: entry.handles,
+    source: "network",
+    fetchedAt: entry.fetchedAt,
+  };
+}
+
+/**
+ * Best-effort prefetch to warm the cache (no throw).
+ * This is intentionally fire-and-forget.
+ */
+export function prefetchAvailableModelHandles(): void {
+  void getAvailableModelHandles().catch(() => {
+    // Ignore failures; UI will handle errors on-demand.
+  });
+}