From ca170c188fc2001c1f380ddc196ae2351f894472 Mon Sep 17 00:00:00 2001
From: Christiaan Arnoldus <christiaan.arnoldus@outlook.com>
Date: Tue, 14 Jul 2026 18:11:49 +0200
Subject: [PATCH 1/2] Disallow fallback to Opus for free models

---
 .../providers/apply-provider-specific-logic.ts        | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.ts b/apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.ts
index 752438bc10..6544b0c09f 100644
--- a/apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.ts
+++ b/apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.ts
@@ -40,6 +40,7 @@ import {
   rewriteChatCompletionsOneOfAsAnyOf,
   isFriendliChatCompletionsRequest,
 } from '@/lib/ai-gateway/schema-rewrite';
+import { isFreeModel } from '@/lib/ai-gateway/is-free-model';
 
 export function getPreferredProviderOrder(requestedModel: string): string[] {
   if (isClaudeModel(requestedModel)) {
@@ -97,12 +98,16 @@ export function applyPreferredProvider(
   }
 }
 
-export function applyGatewayModelsFallback(
+export async function applyGatewayModelsFallback(
   providerId: ProviderId,
   requestedModel: string,
   requestToMutate: GatewayRequest
 ) {
-  if (isFableModel(requestedModel) && (providerId === 'openrouter' || providerId === 'vercel')) {
+  if (
+    !(await isFreeModel(requestedModel)) &&
+    isFableModel(requestedModel) &&
+    (providerId === 'openrouter' || providerId === 'vercel')
+  ) {
     requestToMutate.body.models = [requestedModel, CLAUDE_OPUS_CURRENT_MODEL_ID];
     return;
   }
@@ -122,7 +127,7 @@ export async function applyProviderSpecificLogic(
   sessionId: string | null,
   taskId: string | null
 ) {
-  applyGatewayModelsFallback(provider.id, requestedModel, requestToMutate);
+  await applyGatewayModelsFallback(provider.id, requestedModel, requestToMutate);
   applyTrackingIds(requestToMutate, provider, userId, taskId);
 
   sanitizeBinaryToolResults(requestToMutate);

From 0a53a422e82500b41d469e59cb30f149eaa2b9ca Mon Sep 17 00:00:00 2001
From: chrarnoldus <12196001+chrarnoldus@users.noreply.github.com>
Date: Tue, 14 Jul 2026 16:21:59 +0000
Subject: [PATCH 2/2] Fix async fallback tests

Co-authored-by: kiloconnect[bot] <240665456+kiloconnect[bot]@users.noreply.github.com>
---
 .../providers/apply-provider-specific-logic.test.ts  | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.test.ts b/apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.test.ts
index 73c5ac834f..40d3bf97e6 100644
--- a/apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.test.ts
+++ b/apps/web/src/lib/ai-gateway/providers/apply-provider-specific-logic.test.ts
@@ -21,10 +21,10 @@ function makeRequest(model: string, models?: string[]): GatewayRequest {
 describe('applyGatewayModelsFallback', () => {
   it.each<ProviderId>(['openrouter', 'vercel'])(
     'sets Opus as the Fable fallback for the %s provider',
-    providerId => {
+    async providerId => {
       const request = makeRequest('anthropic/claude-fable-5', ['caller/fallback']);
 
-      applyGatewayModelsFallback(providerId, 'anthropic/claude-fable-5', request);
+      await applyGatewayModelsFallback(providerId, 'anthropic/claude-fable-5', request);
 
       expect(request.body.models).toEqual([
         'anthropic/claude-fable-5',
@@ -33,18 +33,18 @@ describe('applyGatewayModelsFallback', () => {
     }
   );
 
-  it('removes caller-provided fallbacks for Fable on other providers', () => {
+  it('removes caller-provided fallbacks for Fable on other providers', async () => {
     const request = makeRequest('anthropic/claude-fable-5', ['caller/fallback']);
 
-    applyGatewayModelsFallback('martian', 'anthropic/claude-fable-5', request);
+    await applyGatewayModelsFallback('martian', 'anthropic/claude-fable-5', request);
 
     expect(request.body.models).toBeUndefined();
   });
 
-  it('removes caller-provided fallbacks for other models', () => {
+  it('removes caller-provided fallbacks for other models', async () => {
     const request = makeRequest('openai/gpt-4o', ['caller/fallback']);
 
-    applyGatewayModelsFallback('openrouter', 'openai/gpt-4o', request);
+    await applyGatewayModelsFallback('openrouter', 'openai/gpt-4o', request);
 
     expect(request.body.models).toBeUndefined();
   });