fix(@ai-sdk/gateway): add caching property to GatewayProviderOptions type

.changeset/wild-kings-appear.md

@@ -0,0 +1,5 @@
+---
+"@ai-sdk/gateway": patch
+---
+
+Add caching property to GatewayProviderOptions type

content/providers/01-ai-sdk-providers/00-ai-gateway.mdx

@@ -836,6 +836,12 @@ The following gateway provider options are available:
 
   The unique identifier for the entity against which quota is tracked. Used for quota management and enforcement purposes.
 
+- **caching** _string_
+
+  Optional automatic caching configuration for the AI Gateway. Setting this to `'auto'` enables automatic caching of responses to optimize cost and latency.
+
+  Example: `caching: 'auto'`
+
 - **providerTimeouts** _object_
 
   Per-provider timeouts for BYOK credentials in milliseconds. Controls how long to wait for a provider to start responding before falling back to the next available provider.
@@ -963,6 +969,25 @@ const { text } = await generateText({
 });
 ```
 
+#### Caching Example
+
+Set `caching` to `'auto'` to enable automatic caching of responses, which can reduce cost and latency for repeated requests.
+
+```ts
+import type { GatewayProviderOptions } from '@ai-sdk/gateway';
+import { generateText } from 'ai';
+
+const { text } = await generateText({
+  model: 'anthropic/claude-sonnet-4.6',
+  prompt: 'Summarize this report...',
+  providerOptions: {
+    gateway: {
+      caching: 'auto',
+    } satisfies GatewayProviderOptions,
+  },
+});
+```
+
 ### Provider-Specific Options
 
 When using provider-specific options through AI Gateway, use the actual provider name (e.g. `anthropic`, `openai`, not `gateway`) as the key:

packages/gateway/src/gateway-provider-options.test-d.ts

@@ -0,0 +1,10 @@
+import type { GatewayProviderOptions } from './gateway-provider-options';
+import { describe, expectTypeOf, it } from 'vitest';
+
+describe('GatewayProviderOptions', () => {
+  it('caching accepts string', () => {
+    expectTypeOf<GatewayProviderOptions['caching']>().toEqualTypeOf<
+      string | undefined
+    >();
+  });
+});

packages/gateway/src/gateway-provider-options.ts

@@ -92,6 +92,11 @@ const gatewayProviderOptions = lazySchema(() =>
        * Used for quota management and enforcement purposes.
        */
       quotaEntityId: z.string().optional(),
+      /**
+       * Automatic caching configuration for the AI Gateway.
+       * Example: `'auto'`
+       */
+      caching: z.string().optional(),
       /**
        * Per-provider timeouts for BYOK credentials in milliseconds.
        * Controls how long to wait for a provider to start responding