Do not route Fable randomly to Vercel (#3959)

Author: chrarnoldus

apps/web/src/lib/ai-gateway/providers/vercel/index.ts

@@ -24,6 +24,7 @@ import { VERCEL_ROUTING_REDIS_KEY } from '@/lib/redis-keys';
 import { getRandomNumber } from '@/lib/ai-gateway/getRandomNumber';
 import { getVercelModels } from '@/lib/ai-gateway/providers/gateway-models-cache';
 import type { AnthropicProviderOptions } from '@ai-sdk/anthropic';
+import { isFableModel } from '@/lib/ai-gateway/providers/anthropic.constants';
 
 const getVercelRoutingPercentage = createCachedFetch(
   async () => {
@@ -55,6 +56,13 @@ export async function shouldRouteToVercel(
     return false;
   }
 
+  if (isFableModel(requestedModel)) {
+    console.debug(
+      "[shouldRouteToVercel] not routing to Vercel because the Fable->Opus fallback doesn't seem to work"
+    );
+    return false;
+  }
+
   console.debug('[shouldRouteToVercel] randomizing user to either OpenRouter or Vercel');
   const [routingPercentage, vercelModels] = await Promise.all([
     getVercelRoutingPercentage(),