docs: metadata (#197)

* docs: metadata

* improve

Author: dinwwwh

apps/content/.vitepress/config.ts

@@ -70,6 +70,7 @@ export default defineConfig({
         { text: 'File Upload/Download', link: '/docs/file-upload-download' },
         { text: 'Event Iterator (SSE)', link: '/docs/event-iterator' },
         { text: 'Server Action', link: '/docs/server-action' },
+        { text: 'Metadata', link: '/docs/metadata' },
         { text: 'RPC Handler', link: '/docs/rpc-handler' },
         { text: 'Lifecycle', link: '/docs/lifecycle' },
         {

apps/content/docs/metadata.md

@@ -0,0 +1,42 @@
+---
+Title: Metadata
+Description: Enhance your procedures with metadata.
+---
+
+# Metadata
+
+oRPC procedures support metadata, simple key-value pairs that provide extra information to customize behavior.
+
+## Basic Example
+
+```ts twoslash
+import { os } from '@orpc/server'
+// ---cut---
+interface ORPCMetadata {
+  cache?: boolean
+}
+
+const base = os
+  .$meta<ORPCMetadata>({}) // require define initial context [!code highlight]
+  .use(async ({ procedure, next }) => {
+    const result = await next()
+
+    if (!procedure['~orpc'].meta.cache) {
+      return result
+    }
+
+    // Process the result when caching is enabled
+
+    return result
+  })
+
+const example = base
+  .meta({ cache: true }) // [!code highlight]
+  .handler(() => {
+    // Implement your procedure logic here
+  })
+```
+
+:::info
+The `.meta` can be called multiple times; each call [spread merges](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax) the new metadata with the existing metadata or the initial metadata.
+:::

apps/content/docs/openapi/routing.md

@@ -20,6 +20,10 @@ os.route({ method: 'GET', path: '/example', successStatus: 200 })
 os.route({ method: 'POST', path: '/example', successStatus: 201 })
 ```
 
+:::info
+The `.route` can be called multiple times; each call [spread merges](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax) the new route with the existing route.
+:::
+
 ## Path Parameters
 
 By default, path parameters merge with query/body into a single input object. You can modify this behavior as described in the [Input/Output structure docs](/docs/openapi/input-output-structure).