Use candidatesToAst when supported

Author: thecrypticace

packages/tailwindcss-language-server/src/util/v4/design-system.ts

@@ -230,13 +230,20 @@ export async function loadDesignSystem(
       let cache = design.storage[COMPILE_CACHE] as Record<string, AstNode[]>
       let uncached = classes.filter((name) => cache[name] === undefined)
 
-      let css = design.candidatesToCss(uncached)
+      let css = design.candidatesToAst
+        ? design.candidatesToAst(uncached)
+        : design.candidatesToCss(uncached)
 
       let errors: any[] = []
 
       for (let [idx, cls] of uncached.entries()) {
         let str = css[idx]
 
+        if (Array.isArray(str)) {
+          cache[cls] = str
+          continue
+        }
+
         if (str === null) {
           cache[cls] = []
           continue

packages/tailwindcss-language-service/src/util/v4/design-system.ts

@@ -1,6 +1,6 @@
 import postcss from 'postcss'
 import type { NamedVariant } from './candidate'
-import type { Rule } from '../../css'
+import type { AstNode, Rule } from '../../css'
 
 export interface Theme {
   // Prefix didn't exist for earlier Tailwind versions
@@ -54,6 +54,9 @@ export interface DesignSystem {
   // Added in v4.1.16
   // We can patch it into any design system if it doesn't exist though
   storage?: Record<symbol, any>
+
+  // Added in v4.1.18
+  candidatesToAst?(classes: string[]): AstNode[][]
 }
 
 export interface DesignSystem {