fix: avoid v3 hmr content rescan

Author: sonofmagic

.changeset/v3-explicit-candidate-generation.md

@@ -0,0 +1,4 @@
+"weapp-tailwindcss": patch
+---
+
+修复 Tailwind CSS v3 自定义生成引擎在显式候选驱动的增量生成中重复扫描配置 content 的问题，避免 uni-app Vite 热更新时生成 CSS 持续膨胀并拖慢 HMR。

packages/weapp-tailwindcss/src/tailwindcss/v3-engine/generator.ts

@@ -124,12 +124,25 @@ function normalizeConfigObject(config: Config | undefined) {
   return config
 }
 
+function hasExplicitContentInput(options: TailwindV3GenerateOptions) {
+  return options.candidates !== undefined || options.sources !== undefined
+}
+
+function createExplicitContentConfig(rawEntries: Array<{ raw: string, extension: string }>) {
+  return {
+    relative: true,
+    files: rawEntries,
+  }
+}
+
 function createTailwindConfig(source: TailwindV3ResolvedSource, options: TailwindV3GenerateOptions) {
   const config = {
     ...(normalizeConfigObject(source.configObject) ?? {}),
   } as Config
   const rawEntries = createRawContentEntries(options.candidates ?? [], options.sources ?? [])
-  config.content = mergeContent(config.content, rawEntries) as Config['content']
+  config.content = hasExplicitContentInput(options)
+    ? createExplicitContentConfig(rawEntries) as Config['content']
+    : mergeContent(config.content, rawEntries) as Config['content']
   return config
 }
 

packages/weapp-tailwindcss/test/tailwindcss/v3-engine.test.ts

@@ -249,6 +249,41 @@ describe('tailwindcss v3 engine', () => {
     expect(second.css.match(/\.bg-blue-500/g) ?? []).toHaveLength(1)
   })
 
+  it('does not rescan configured content when explicit candidates drive v3 incremental generation', async () => {
+    const source = await resolveTailwindV3Source({
+      css: '@tailwind utilities;',
+      base: process.cwd(),
+      config: undefined,
+    })
+    source.configObject = {
+      content: [
+        {
+          raw: '<view class="text-[88rpx] bg-[#4268EA]"></view>',
+          extension: 'html',
+        },
+      ],
+    }
+    const engine = createTailwindV3Engine(source)
+
+    const first = await engine.generate({
+      candidates: ['bg-[#4268EA]'],
+      incrementalCache: true,
+    })
+    const second = await engine.generate({
+      candidates: ['bg-[#4268EA]', 'bg-[red]'],
+      incrementalCache: true,
+    })
+
+    expect(first.classSet).toEqual(new Set(['bg-[#4268EA]']))
+    expect(first.css).toContain('.bg-_b_h4268EA_B')
+    expect(first.css).not.toContain('88rpx')
+    expect(second.classSet).toEqual(new Set(['bg-[#4268EA]', 'bg-[red]']))
+    expect(second.css).toContain('.bg-_bred_B')
+    expect(second.css).not.toContain('88rpx')
+    expect(second.css.length - first.css.length).toBeLessThan(400)
+    expect(second.css.match(/\.bg-_b_h4268EA_B/g) ?? []).toHaveLength(1)
+  })
+
   it('normalizes default export configs before generating plugin components', async () => {
     const source = await resolveTailwindV3Source({
       css: '@tailwind components;',