skill: add gateway instructions (#11995)

Agents often mistake how to use AI Gateway.

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: nicoalbanese

skills/use-ai-sdk/SKILL.md

@@ -36,6 +36,8 @@ Use these resources for current API details, examples, and usage patterns.
 
 For common errors and troubleshooting, see [Common Errors Reference](references/common-errors.md).
 
+For using Vercel AI Gateway, see [AI Gateway Reference](references/ai-gateway.md).
+
 ## Provider-Specific Information (ai@6.0.34+)
 
 For questions about specific providers (OpenAI, Anthropic, Google, etc.), search their dedicated packages:

skills/use-ai-sdk/references/ai-gateway.md

@@ -0,0 +1,41 @@
+---
+title: Vercel AI Gateway
+description: Reference for using Vercel AI Gateway with the AI SDK.
+---
+
+# Vercel AI Gateway
+
+The Vercel AI Gateway is the fastest way to get started with the AI SDK. It provides access to models from OpenAI, Anthropic, Google, and other providers through a single API.
+
+## Authentication
+
+Authenticate with OIDC (for Vercel deployments) or an [AI Gateway API key](https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai-gateway%2Fapi-keys&title=AI+Gateway+API+Keys):
+
+```env filename=".env.local"
+AI_GATEWAY_API_KEY=your_api_key_here
+```
+
+## Usage
+
+The AI Gateway is the default global provider, so you can access models using a simple string:
+
+```ts
+import { generateText } from 'ai';
+
+const { text } = await generateText({
+  model: 'anthropic/claude-sonnet-4.5',
+  prompt: 'What is love?',
+});
+```
+
+You can also explicitly import and use the gateway provider:
+
+```ts
+// Option 1: Import from 'ai' package (included by default)
+import { gateway } from 'ai';
+model: gateway('anthropic/claude-sonnet-4.5');
+
+// Option 2: Install and import from '@ai-sdk/gateway' package
+import { gateway } from '@ai-sdk/gateway';
+model: gateway('anthropic/claude-sonnet-4.5');
+```