diff --git a/packages/ai/src/llm/opus-4-1.ts b/packages/ai/src/llm/opus-4-1.ts
new file mode 100644
index 000000000..24f6020a3
--- /dev/null
+++ b/packages/ai/src/llm/opus-4-1.ts
@@ -0,0 +1,65 @@
+import type { LanguageModelV2 } from '@ai-sdk/provider';
+import { createFallback } from './ai-fallback';
+import { anthropicModel } from './providers/anthropic';
+import { vertexModel } from './providers/vertex';
+
+// Lazy initialization to allow mocking in tests
+let _opus41Instance: ReturnType<typeof createFallback> | null = null;
+
+function initializeOpus41() {
+  if (_opus41Instance) {
+    return _opus41Instance;
+  }
+
+  // Build models array based on available credentials
+  const models: LanguageModelV2[] = [];
+
+  // Only include Anthropic if API key is available
+  if (process.env.ANTHROPIC_API_KEY) {
+    try {
+      models.push(anthropicModel('claude-opus-4-1-20250805'));
+      console.info('Opus41: Anthropic model added to fallback chain');
+    } catch (error) {
+      console.warn('Opus41: Failed to initialize Anthropic model:', error);
+    }
+  }
+
+  // Ensure we have at least one model
+  if (models.length === 0) {
+    throw new Error(
+      'No AI models available. Please set either Vertex AI (VERTEX_CLIENT_EMAIL and VERTEX_PRIVATE_KEY) or Anthropic (ANTHROPIC_API_KEY) credentials.'
+    );
+  }
+
+  console.info(`Opus41: Initialized with ${models.length} model(s) in fallback chain`);
+
+  _opus41Instance = createFallback({
+    models,
+    modelResetInterval: 60000,
+    retryAfterOutput: true,
+    onError: (err) => console.error(`FALLBACK.  Here is the error: ${err}`),
+  });
+
+  return _opus41Instance;
+}
+
+// Export a proxy that initializes on first use
+export const Opus41 = new Proxy({} as ReturnType<typeof createFallback>, {
+  get(_target, prop) {
+    const instance = initializeOpus41();
+    // Direct property access without receiver to avoid proxy conflicts
+    return instance[prop as keyof typeof instance];
+  },
+  has(_target, prop) {
+    const instance = initializeOpus41();
+    return prop in instance;
+  },
+  ownKeys(_target) {
+    const instance = initializeOpus41();
+    return Reflect.ownKeys(instance);
+  },
+  getOwnPropertyDescriptor(_target, prop) {
+    const instance = initializeOpus41();
+    return Reflect.getOwnPropertyDescriptor(instance, prop);
+  },
+});
diff --git a/packages/ai/src/llm/sonnet-4.ts b/packages/ai/src/llm/sonnet-4.ts
index 86e090f4a..8c282766a 100644
--- a/packages/ai/src/llm/sonnet-4.ts
+++ b/packages/ai/src/llm/sonnet-4.ts
@@ -34,6 +34,15 @@ function initializeSonnet4() {
     }
   }
 
+  if (process.env.ANTHROPIC_API_KEY) {
+    try {
+      models.push(anthropicModel('claude-opus-4-1-20250805'));
+      console.info('Opus41: Anthropic model added to fallback chain');
+    } catch (error) {
+      console.warn('Opus41: Failed to initialize Anthropic model:', error);
+    }
+  }
+
   // Ensure we have at least one model
   if (models.length === 0) {
     throw new Error(