Rework Vite plugin to support lightningcss pre processor and fast rebuilds

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add new standalone builds of Tailwind CSS v4 ([#14270](https://github.com/tailwindlabs/tailwindcss/pull/14270))
 - Support JavaScript configuration files using `@config` ([#14239](https://github.com/tailwindlabs/tailwindcss/pull/14239))
 - Support plugin options in `@plugin` ([#14264](https://github.com/tailwindlabs/tailwindcss/pull/14264))
+- Add support for using the Vite extension with `css.transformer` set to `lightningcss` ([#14269](https://github.com/tailwindlabs/tailwindcss/pull/14269))
 
 ### Fixed
 
@@ -27,6 +28,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix fallback values when using the CSS `theme()` function ([#14262](https://github.com/tailwindlabs/tailwindcss/pull/14262))
 - Fix support for declaration fallbacks in plugins ([#14265](https://github.com/tailwindlabs/tailwindcss/pull/14265))
 - Support bare values when using `tailwindcss/defaultTheme` ([#14257](https://github.com/tailwindlabs/tailwindcss/pull/14257))
+- Correctly update builds when using the Vite extension with `build --watch` ([#14269](https://github.com/tailwindlabs/tailwindcss/pull/14269))
 
 ### Changed
 

integrations/utils.ts

@@ -1,7 +1,7 @@
 import dedent from 'dedent'
 import fastGlob from 'fast-glob'
 import killPort from 'kill-port'
-import { execSync, spawn } from 'node:child_process'
+import { exec, spawn } from 'node:child_process'
 import fs from 'node:fs/promises'
 import net from 'node:net'
 import { homedir, platform, tmpdir } from 'node:os'
@@ -89,11 +89,23 @@ export function test(
             console.log(`> cd ${relative}`)
           }
           if (debug) console.log(`> ${command}`)
-          return execSync(command, {
-            cwd,
-            stdio: 'pipe',
-            ...childProcessOptions,
-          }).toString()
+          return new Promise((resolve, reject) => {
+            exec(
+              command,
+              {
+                cwd,
+                ...childProcessOptions,
+              },
+              (error, stdout, stderr) => {
+                if (error) {
+                  console.error(stderr)
+                  reject(error)
+                } else {
+                  resolve(stdout.toString())
+                }
+              },
+            )
+          })
         },
         async spawn(command: string, childProcessOptions: ChildProcessOptions = {}) {
           let resolveDisposal: (() => void) | undefined