feat(byok): fetch live models dynamically from provider api with user api key on input

memento-note/app/api/user/api-keys/live-models/route.ts

@@ -0,0 +1,45 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { auth } from '@/auth';
+import { getEffectiveTier } from '@/lib/entitlements';
+import { getAllowedByokProviders, isByokProviderAllowed } from '@/lib/byok';
+import { fetchLiveModelsForProvider } from '@/lib/ai/models-list';
+import { VALID_PROVIDERS, type AiGatewayProvider } from '@/lib/ai/router';
+
+/**
+ * GET /api/user/api-keys/live-models?provider=<provider>&key=<api_key>&baseUrl=<optional_custom_url>
+ *
+ * Dynamically queries the third-party provider's API with the user's key to fetch
+ * actual available models dynamically.
+ */
+export async function GET(request: NextRequest) {
+  const session = await auth();
+  if (!session?.user?.id) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+  }
+
+  const tier = await getEffectiveTier(session.user.id);
+  if (tier === 'BASIC') {
+    return NextResponse.json({ error: 'Forbidden' }, { status: 403 });
+  }
+
+  const { searchParams } = request.nextUrl;
+  const provider = searchParams.get('provider') as AiGatewayProvider;
+  const apiKey = searchParams.get('key');
+  const baseUrl = searchParams.get('baseUrl') ?? undefined;
+
+  if (!provider || !apiKey) {
+    return NextResponse.json({ error: 'Missing parameters' }, { status: 400 });
+  }
+
+  if (!VALID_PROVIDERS.has(provider)) {
+    return NextResponse.json({ error: 'Invalid provider' }, { status: 400 });
+  }
+
+  if (!isByokProviderAllowed(tier, provider)) {
+    return NextResponse.json({ error: 'Tier restricted' }, { status: 403 });
+  }
+
+  const models = await fetchLiveModelsForProvider(provider, apiKey, baseUrl);
+
+  return NextResponse.json({ success: true, models });
+}