From dc1195e13985104c5cda2a0dde1b9ba8a0403579 Mon Sep 17 00:00:00 2001
From: valadaptive <valadaptive@protonmail.com>
Date: Wed, 13 Aug 2025 17:44:22 -0400
Subject: [PATCH] feat(preview): allow setting compression options

---
 docs/config/preview-options.md    |  7 +++++++
 packages/vite/src/node/preview.ts | 18 ++++++++++++++----
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/docs/config/preview-options.md b/docs/config/preview-options.md
index acab6a3486cf8a..29a9dcb62ac089 100644
--- a/docs/config/preview-options.md
+++ b/docs/config/preview-options.md
@@ -96,3 +96,10 @@ See [`server.cors`](./server-options#server-cors) for more details.
 - **Type:** `OutgoingHttpHeaders`
 
 Specify server response headers.
+
+## preview.compression
+
+- **Type:** `CompressionOptions`
+- Default: `{ threshold: 1024, level: -1, brotli: false, gzip: true, mimes: /text|javascript|\/json|xml/i }`
+
+Configure compression for files served by the preview server. See [`@polka/compression`](https://www.npmjs.com/package/@polka/compression#options) for more details.
diff --git a/packages/vite/src/node/preview.ts b/packages/vite/src/node/preview.ts
index 865b78adb91755..51073078c9f4f2 100644
--- a/packages/vite/src/node/preview.ts
+++ b/packages/vite/src/node/preview.ts
@@ -1,7 +1,9 @@
 import fs from 'node:fs'
 import path from 'node:path'
 import sirv from 'sirv'
-import compression from '@polka/compression'
+import compression, {
+  type Options as CompressionOptions,
+} from '@polka/compression'
 import connect from 'connect'
 import type { Connect } from 'dep-types/connect'
 import corsMiddleware from 'cors'
@@ -46,10 +48,17 @@ import {
 } from './server/pluginContainer'
 import type { MinimalPluginContextWithoutEnvironment } from './plugin'
 
-export interface PreviewOptions extends CommonServerOptions {}
+export { type Options as CompressionOptions } from '@polka/compression'
+
+export interface PreviewOptions extends CommonServerOptions {
+  compression?: CompressionOptions
+}
 
 export interface ResolvedPreviewOptions
-  extends RequiredExceptFor<PreviewOptions, 'host' | 'https' | 'proxy'> {}
+  extends RequiredExceptFor<
+    PreviewOptions,
+    'host' | 'https' | 'proxy' | 'compression'
+  > {}
 
 export function resolvePreviewOptions(
   preview: PreviewOptions | undefined,
@@ -68,6 +77,7 @@ export function resolvePreviewOptions(
     proxy: preview?.proxy ?? server.proxy,
     cors: preview?.cors ?? server.cors,
     headers: preview?.headers ?? server.headers,
+    compression: preview?.compression,
   }
 }
 
@@ -224,7 +234,7 @@ export async function preview(
     app.use(proxyMiddleware(httpServer, proxy, config))
   }
 
-  app.use(compression())
+  app.use(compression(config.preview.compression))
 
   // base
   if (config.base !== '/') {