From 351a4f2e060d40352abfba104e38c2565bfcc0de Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 11:21:45 +0800
Subject: [PATCH 01/13] fix(postcss): remove empty mini-program at-rules

---
 .changeset/clean-empty-media-rules.md         |  6 ++++
 .../src/compat/mini-program-css/index.ts      |  1 +
 .../mini-program-css/prune-generated.ts       |  8 ++---
 .../compat/mini-program-css/root-cleanups.ts  | 13 +++++--
 packages/postcss/src/index.ts                 |  1 +
 packages/postcss/src/plugins/post.ts          |  2 ++
 .../postcss/src/vite-css-rules/containment.ts |  3 +-
 .../postcss/src/vite-css-rules/coverage.ts    |  9 +----
 .../src/vite-css-rules/mini-program.ts        |  2 +-
 .../test/mini-program-generated-css.test.ts   | 18 ++++++++++
 .../vite/generate-bundle/final-css-assets.ts  | 14 ++++++--
 .../vite/processed-css-assets/cleanup.ts      | 16 ++-------
 .../bundlers/vite-plugin.bundle.unit.test.ts  | 36 +++++++++++++++++++
 13 files changed, 95 insertions(+), 34 deletions(-)
 create mode 100644 .changeset/clean-empty-media-rules.md

diff --git a/.changeset/clean-empty-media-rules.md b/.changeset/clean-empty-media-rules.md
new file mode 100644
index 000000000..843943314
--- /dev/null
+++ b/.changeset/clean-empty-media-rules.md
@@ -0,0 +1,6 @@
+---
+"@weapp-tailwindcss/postcss": patch
+"weapp-tailwindcss": patch
+---
+
+修复小程序样式在非主样式块、缓存产物与嵌套条件规则中残留空 `@media`、`@supports` 等块级 at-rule，避免生成的 WXSS 因空媒体查询触发编译错误。
diff --git a/packages/postcss/src/compat/mini-program-css/index.ts b/packages/postcss/src/compat/mini-program-css/index.ts
index 9dc05cfaf..60aac6e1f 100644
--- a/packages/postcss/src/compat/mini-program-css/index.ts
+++ b/packages/postcss/src/compat/mini-program-css/index.ts
@@ -17,5 +17,6 @@ export {
 } from './prune-generated'
 export {
   hasMiniProgramCssSpecificityPlaceholders,
+  removeEmptyAtRules,
   stripMiniProgramCssSpecificityPlaceholders,
 } from './root-cleanups'
diff --git a/packages/postcss/src/compat/mini-program-css/prune-generated.ts b/packages/postcss/src/compat/mini-program-css/prune-generated.ts
index f130708da..52ced8a74 100644
--- a/packages/postcss/src/compat/mini-program-css/prune-generated.ts
+++ b/packages/postcss/src/compat/mini-program-css/prune-generated.ts
@@ -11,7 +11,7 @@ import {
   isPseudoContentInitRule,
   usesTwContentVariable,
 } from './predicates'
-import { removeSpecificityPlaceholders, removeTailwindContainerMaxWidthMediaRules, removeTailwindContainerWidthRules, removeUnsupportedModernColorDeclarations } from './root-cleanups'
+import { removeEmptyAtRules, removeSpecificityPlaceholders, removeTailwindContainerMaxWidthMediaRules, removeTailwindContainerWidthRules, removeUnsupportedModernColorDeclarations } from './root-cleanups'
 import { getRuleSelectors, isMiniProgramNativeElementSelector, isUnsupportedBrowserPreflightSelector, MINI_PROGRAM_ELEMENT_SCOPE_SELECTOR, MINI_PROGRAM_ELEMENT_SCOPE_SELECTORS } from './selectors'
 
 const DEFAULT_WEAPP_VARIABLE_SCOPE = 'page,.tw-root,wx-root-portal-content,:host'
@@ -310,11 +310,7 @@ export function pruneMiniProgramGeneratedCss(
     ensureMiniProgramElementContentInit(root)
   }
 
-  root.walkAtRules((atRule) => {
-    if (!atRule.nodes || atRule.nodes.length === 0) {
-      atRule.remove()
-    }
-  })
+  removeEmptyAtRules(root)
 
   return root.toString()
 }
diff --git a/packages/postcss/src/compat/mini-program-css/root-cleanups.ts b/packages/postcss/src/compat/mini-program-css/root-cleanups.ts
index 36e4cab12..ed9a8ade9 100644
--- a/packages/postcss/src/compat/mini-program-css/root-cleanups.ts
+++ b/packages/postcss/src/compat/mini-program-css/root-cleanups.ts
@@ -80,11 +80,20 @@ function isEffectivelyEmptyContainer(container: postcss.Container) {
 }
 
 export function removeEmptyAtRules(root: postcss.Root) {
+  const atRules: postcss.AtRule[] = []
   root.walkAtRules((atRule) => {
-    if (isEffectivelyEmptyContainer(atRule)) {
+    atRules.push(atRule)
+  })
+
+  let removed = 0
+  for (let index = atRules.length - 1; index >= 0; index--) {
+    const atRule = atRules[index]
+    if (atRule?.parent && isEffectivelyEmptyContainer(atRule)) {
       atRule.remove()
+      removed++
     }
-  })
+  }
+  return removed
 }
 
 function removeEmptyAtRuleAncestors(parent: postcss.Container | undefined) {
diff --git a/packages/postcss/src/index.ts b/packages/postcss/src/index.ts
index e2bae8908..4233764c0 100644
--- a/packages/postcss/src/index.ts
+++ b/packages/postcss/src/index.ts
@@ -21,6 +21,7 @@ export {
   hoistTailwindPreflightBase,
   normalizeMiniProgramGeneratedCssForPostcss,
   pruneMiniProgramGeneratedCss,
+  removeEmptyAtRules,
   removeUnsupportedAtSupports,
   removeUnsupportedCascadeLayers,
   removeUnsupportedMiniProgramAtRules,
diff --git a/packages/postcss/src/plugins/post.ts b/packages/postcss/src/plugins/post.ts
index 7ccc6a3eb..0867de155 100644
--- a/packages/postcss/src/plugins/post.ts
+++ b/packages/postcss/src/plugins/post.ts
@@ -2,6 +2,7 @@
 import type { Declaration, Plugin, PluginCreator, Root, Rule } from 'postcss'
 import type { IStyleHandlerOptions } from '../types'
 import { defu } from '@weapp-tailwindcss/shared'
+import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { getRuleSelectors, isMiniProgramThemeScopeSelector, MINI_PROGRAM_ELEMENT_SCOPE_SELECTOR } from '../compat/mini-program-css/selectors'
 import { normalizeMiniProgramPrefixedDeclaration, removeUnsupportedMiniProgramPrefixedAtRule } from '../compat/mini-program-prefixes'
 import { normalizeTailwindcssRpxDeclaration } from '../compat/tailwindcss-rpx'
@@ -226,6 +227,7 @@ const postcssWeappTailwindcssPostPlugin: PostcssWeappTailwindcssRenamePlugin = (
     if (shouldInjectTailwindcssV4Defaults || (opts.majorVersion === 4 && usesTailwindcssV4ContentVariable(root))) {
       injectMissingTailwindcssV4Defaults(root)
     }
+    removeEmptyAtRules(root)
   }
 
   if (enableMainChunkTransforms) {
diff --git a/packages/postcss/src/vite-css-rules/containment.ts b/packages/postcss/src/vite-css-rules/containment.ts
index 4f1ab2794..5a55924c1 100644
--- a/packages/postcss/src/vite-css-rules/containment.ts
+++ b/packages/postcss/src/vite-css-rules/containment.ts
@@ -1,5 +1,6 @@
+import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { postcss } from '../postcss-runtime'
-import { isCssRuleCoveredByDeclarations, removeEmptyAtRules } from './coverage'
+import { isCssRuleCoveredByDeclarations } from './coverage'
 import { collectCssRuleContentKeys, collectCssRuleDeclarationKeyMap, collectNormalizedCssNodes, getCssRuleContentKey, normalizeCssForContainment } from './structure'
 
 export function filterExistingCssRules(baseCss: string, css: string) {
diff --git a/packages/postcss/src/vite-css-rules/coverage.ts b/packages/postcss/src/vite-css-rules/coverage.ts
index d02e69777..a5b2468c2 100644
--- a/packages/postcss/src/vite-css-rules/coverage.ts
+++ b/packages/postcss/src/vite-css-rules/coverage.ts
@@ -1,3 +1,4 @@
+import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { postcss } from '../postcss-runtime'
 import { collectCssRuleDeclarationKeys, collectCssRuleDeclarationRecords, collectCssRuleDeclarations, getCssRuleStructuralKey, isCoveredByBaseVarFallbackDeclaration, isEquivalentVarFallbackDeclaration, normalizeCssDeclarationKey, normalizeCssForContainment, parseVarReferenceValue } from './structure'
 
@@ -170,11 +171,3 @@ export function mergeCoveredCssRuleDeclarations(baseCss: string, css: string) {
     return { baseCss, css, changed: false }
   }
 }
-
-export function removeEmptyAtRules(root: postcss.Root) {
-  root.walkAtRules((atRule) => {
-    if (atRule.nodes && atRule.nodes.every(node => node.type === 'comment')) {
-      atRule.remove()
-    }
-  })
-}
diff --git a/packages/postcss/src/vite-css-rules/mini-program.ts b/packages/postcss/src/vite-css-rules/mini-program.ts
index 598bcf591..2aae89a8b 100644
--- a/packages/postcss/src/vite-css-rules/mini-program.ts
+++ b/packages/postcss/src/vite-css-rules/mini-program.ts
@@ -1,7 +1,7 @@
 import type { Node, Selector } from 'postcss-selector-parser'
 import selectorParser from 'postcss-selector-parser'
+import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { postcss } from '../postcss-runtime'
-import { removeEmptyAtRules } from './coverage'
 import { collectCssRuleDeclarationRecords, collectCssRuleDeclarations, getCssRuleStructuralKeyWithSelectorKey, MINI_PROGRAM_PREFLIGHT_SELECTOR_KEY, MINI_PROGRAM_PREFLIGHT_SELECTOR_KEYS, MINI_PROGRAM_THEME_SCOPE_SELECTOR_KEY, MINI_PROGRAM_THEME_SCOPE_SELECTOR_KEYS, normalizeCssDeclarationKey } from './structure'
 
 function normalizeSimpleMiniProgramSelectorNode(node: Node) {
diff --git a/packages/postcss/test/mini-program-generated-css.test.ts b/packages/postcss/test/mini-program-generated-css.test.ts
index c44e6c1b1..60e47045b 100644
--- a/packages/postcss/test/mini-program-generated-css.test.ts
+++ b/packages/postcss/test/mini-program-generated-css.test.ts
@@ -107,6 +107,24 @@ describe('mini-program generated css cleanup', () => {
     expect(css).not.toContain('box-sizing:border-box')
   })
 
+  it('removes empty conditional at-rules from non-main mini-program chunks', async () => {
+    const styleHandler = createStyleHandler({
+      majorVersion: 4,
+    })
+    const { css } = await styleHandler([
+      '@media (prefers-color-scheme: light) {}',
+      '@media (prefers-color-scheme: dark) { /* removed declarations */ }',
+      '@media screen { @supports (display: grid) {} }',
+      '.keep{color:red}',
+    ].join('\n'), {
+      isMainChunk: false,
+    })
+
+    expect(css).not.toContain('@media')
+    expect(css).not.toContain('@supports')
+    expect(css).toContain('.keep{color:red}')
+  })
+
   it('preserves user page custom properties that use Tailwind v4 theme namespaces', async () => {
     const styleHandler = createStyleHandler({
       majorVersion: 4,
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
index ce411cd82..fbb36212c 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
@@ -6,6 +6,7 @@ import {
   stripMiniProgramCssSpecificityPlaceholders,
 } from '@/bundlers/shared/css-cleanup'
 import { AssetEmissionPlan } from '@/compiler'
+import { removeCommentOnlyAtRules } from '../processed-css-assets/cleanup'
 import { applyViteAssetEmissionPlan } from './asset-emission-plan'
 
 function readAssetSource(output: OutputAsset) {
@@ -53,8 +54,9 @@ export async function finalizeMiniProgramCssAssets(
     if (rawSource.trim().length === 0) {
       continue
     }
+    const structurallyCleanSource = removeCommentOnlyAtRules(rawSource)
     if (options.lastCssResultByFile?.has(file)) {
-      const outputCss = stripMiniProgramCssSpecificityPlaceholders(rawSource)
+      const outputCss = stripMiniProgramCssSpecificityPlaceholders(structurallyCleanSource)
       if (outputCss !== rawSource) {
         plan.write(file, outputCss)
         writeTargets.set(file, output)
@@ -66,11 +68,19 @@ export async function finalizeMiniProgramCssAssets(
       continue
     }
     if (!shouldFinalizeMiniProgramCssAsset(rawSource)) {
+      if (structurallyCleanSource !== rawSource) {
+        plan.write(file, structurallyCleanSource)
+        writeTargets.set(file, output)
+        options.recordCssAssetResult?.(file, structurallyCleanSource)
+        options.onUpdate(file, rawSource, structurallyCleanSource)
+        options.debug?.('remove empty mini-program css at-rules: %s bytes=%d', file, structurallyCleanSource.length)
+        updated++
+      }
       continue
     }
 
     const cssHandlerOptions = options.getCssHandlerOptions(file)
-    const { css } = await options.styleHandler(rawSource, {
+    const { css } = await options.styleHandler(structurallyCleanSource, {
       ...cssHandlerOptions,
       autoprefixer: false,
       cssOptions: {
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
index 8389e75ab..20552ffec 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
@@ -1,7 +1,7 @@
 import type { OutputAsset, OutputBundle } from 'rollup'
 import type { CollectViteProcessedCssAssetOptions } from './markers-imports'
 import type { InternalUserDefinedOptions } from '@/types'
-import { isMiniProgramLocalCssImportRequest, parseTailwindCssDirectiveRequest, postcss } from '@weapp-tailwindcss/postcss'
+import { isMiniProgramLocalCssImportRequest, parseTailwindCssDirectiveRequest, postcss, removeEmptyAtRules } from '@weapp-tailwindcss/postcss'
 import path from 'pathe'
 import { normalizeOutputPathKey } from '../../shared/module-graph'
 import { appendCss, collectImportedStyleFiles, createCssAssetPipelineContext, getAssetFile, isStyleImportRequest, readAssetSource } from './markers-imports'
@@ -76,19 +76,7 @@ export function removeCommentOnlyAtRules(css: string) {
   }
   try {
     const root = postcss.parse(css)
-    let changed = false
-    root.walkAtRules((atRule) => {
-      if (!atRule.nodes || atRule.nodes.length === 0) {
-        return
-      }
-      const hasCss = atRule.nodes.some(node => node.type !== 'comment')
-      if (hasCss) {
-        return
-      }
-      atRule.remove()
-      changed = true
-    })
-    return changed ? root.toString() : css
+    return removeEmptyAtRules(root) > 0 ? root.toString() : css
   }
   catch {
     return css
diff --git a/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts b/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
index d33318a12..bcd691ea2 100644
--- a/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
+++ b/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
@@ -15249,6 +15249,42 @@ page {
     expect(onUpdate).toHaveBeenCalledWith('cached.wxss', expect.any(String), css)
   })
 
+  it('removes empty conditional at-rules from cached mini-program css assets', async () => {
+    const { finalizeMiniProgramCssAssets } = await import('@/bundlers/vite/generate-bundle/final-css-assets')
+    const styleHandler = vi.fn(async (code: string) => ({ css: code }))
+    const bundle = {
+      'app.wxss': {
+        ...createRollupAsset([
+          '@media (prefers-color-scheme: light) {}',
+          '@media (prefers-color-scheme: dark) { /* removed declarations */ }',
+          '@media screen { @supports (display: grid) {} }',
+          '.keep{color:red}',
+        ].join('\n')),
+        fileName: 'app.wxss',
+      },
+    }
+    const onUpdate = vi.fn()
+    const recordCssAssetResult = vi.fn()
+
+    await finalizeMiniProgramCssAssets(bundle, {
+      cssMatcher: file => file.endsWith('.wxss'),
+      getCssHandlerOptions: () => ({ isMainChunk: true } as any),
+      isWebGeneratorTarget: false,
+      lastCssResultByFile: new Map([['app.wxss', 'cached']]),
+      onUpdate,
+      recordCssAssetResult,
+      styleHandler,
+    })
+
+    const css = (bundle['app.wxss'] as OutputAsset).source.toString()
+    expect(css).not.toContain('@media')
+    expect(css).not.toContain('@supports')
+    expect(css).toContain('.keep{color:red}')
+    expect(styleHandler).not.toHaveBeenCalled()
+    expect(recordCssAssetResult).toHaveBeenCalledWith('app.wxss', css)
+    expect(onUpdate).toHaveBeenCalledWith('app.wxss', expect.any(String), css)
+  })
+
   it('logs css diffs when vite css diff debugging is enabled', async () => {
     const previousDebugCssDiff = process.env.WEAPP_TW_VITE_DEBUG_CSS_DIFF
     process.env.WEAPP_TW_VITE_DEBUG_CSS_DIFF = '1'

From 14d099cd9502d6e7a7a7a0cab267457f63b4a0ce Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 12:03:21 +0800
Subject: [PATCH 02/13] perf(postcss): avoid redundant empty at-rule scans

---
 .../compat/mini-program-css/root-cleanups.ts  | 22 ++++++++++---------
 packages/postcss/src/plugins/post.ts          |  4 +++-
 .../vite/processed-css-assets/cleanup.ts      |  2 +-
 3 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/packages/postcss/src/compat/mini-program-css/root-cleanups.ts b/packages/postcss/src/compat/mini-program-css/root-cleanups.ts
index ed9a8ade9..36f607cfd 100644
--- a/packages/postcss/src/compat/mini-program-css/root-cleanups.ts
+++ b/packages/postcss/src/compat/mini-program-css/root-cleanups.ts
@@ -80,19 +80,21 @@ function isEffectivelyEmptyContainer(container: postcss.Container) {
 }
 
 export function removeEmptyAtRules(root: postcss.Root) {
-  const atRules: postcss.AtRule[] = []
-  root.walkAtRules((atRule) => {
-    atRules.push(atRule)
-  })
-
   let removed = 0
-  for (let index = atRules.length - 1; index >= 0; index--) {
-    const atRule = atRules[index]
-    if (atRule?.parent && isEffectivelyEmptyContainer(atRule)) {
-      atRule.remove()
-      removed++
+  const visit = (container: postcss.Container) => {
+    for (const node of [...(container.nodes ?? [])]) {
+      if (!('nodes' in node) || node.nodes === undefined) {
+        continue
+      }
+      visit(node)
+      if (node.type === 'atrule' && node.parent && isEffectivelyEmptyContainer(node)) {
+        node.remove()
+        removed++
+      }
     }
   }
+
+  visit(root)
   return removed
 }
 
diff --git a/packages/postcss/src/plugins/post.ts b/packages/postcss/src/plugins/post.ts
index 0867de155..eb5013994 100644
--- a/packages/postcss/src/plugins/post.ts
+++ b/packages/postcss/src/plugins/post.ts
@@ -227,7 +227,9 @@ const postcssWeappTailwindcssPostPlugin: PostcssWeappTailwindcssRenamePlugin = (
     if (shouldInjectTailwindcssV4Defaults || (opts.majorVersion === 4 && usesTailwindcssV4ContentVariable(root))) {
       injectMissingTailwindcssV4Defaults(root)
     }
-    removeEmptyAtRules(root)
+    if (!enableMainChunkTransforms) {
+      removeEmptyAtRules(root)
+    }
   }
 
   if (enableMainChunkTransforms) {
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
index 20552ffec..8173cf850 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
@@ -71,7 +71,7 @@ export function restoreCssImportAtRules(source: string, filtered: string, file?:
 }
 
 export function removeCommentOnlyAtRules(css: string) {
-  if (!css.includes('@')) {
+  if (!css.includes('@') || !/@[a-z-]+\b[^{};]*\{(?:\s|\/\*[\s\S]*?\*\/)*\}/i.test(css)) {
     return css
   }
   try {

From 511f35a33deedd2db102b05d7fab7f773c56e630 Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 12:10:32 +0800
Subject: [PATCH 03/13] perf(postcss): clean empty at-rules in lifecycle

---
 packages/postcss/src/plugins/post.ts             | 16 ++++++----------
 .../vite/generate-bundle/final-css-assets.ts     |  5 +++--
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/packages/postcss/src/plugins/post.ts b/packages/postcss/src/plugins/post.ts
index eb5013994..4dac29c38 100644
--- a/packages/postcss/src/plugins/post.ts
+++ b/packages/postcss/src/plugins/post.ts
@@ -2,7 +2,6 @@
 import type { Declaration, Plugin, PluginCreator, Root, Rule } from 'postcss'
 import type { IStyleHandlerOptions } from '../types'
 import { defu } from '@weapp-tailwindcss/shared'
-import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { getRuleSelectors, isMiniProgramThemeScopeSelector, MINI_PROGRAM_ELEMENT_SCOPE_SELECTOR } from '../compat/mini-program-css/selectors'
 import { normalizeMiniProgramPrefixedDeclaration, removeUnsupportedMiniProgramPrefixedAtRule } from '../compat/mini-program-prefixes'
 import { normalizeTailwindcssRpxDeclaration } from '../compat/tailwindcss-rpx'
@@ -227,13 +226,10 @@ const postcssWeappTailwindcssPostPlugin: PostcssWeappTailwindcssRenamePlugin = (
     if (shouldInjectTailwindcssV4Defaults || (opts.majorVersion === 4 && usesTailwindcssV4ContentVariable(root))) {
       injectMissingTailwindcssV4Defaults(root)
     }
-    if (!enableMainChunkTransforms) {
-      removeEmptyAtRules(root)
-    }
   }
 
-  if (enableMainChunkTransforms) {
-    p.AtRuleExit = (atRule) => {
+  p.AtRuleExit = (atRule) => {
+    if (enableMainChunkTransforms) {
       removeUnsupportedMiniProgramPrefixedAtRule(atRule)
       /**
        * @description 移除 property
@@ -244,10 +240,10 @@ const postcssWeappTailwindcssPostPlugin: PostcssWeappTailwindcssRenamePlugin = (
         }
         atRule.remove()
       }
-      /**
-       * 清除空节点
-       */
-      atRule.nodes?.length === 0 && atRule.remove()
+    }
+
+    if (atRule.nodes?.every(node => node.type === 'comment')) {
+      atRule.remove()
     }
   }
   return p
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
index fbb36212c..77a8e6cf1 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
@@ -54,8 +54,8 @@ export async function finalizeMiniProgramCssAssets(
     if (rawSource.trim().length === 0) {
       continue
     }
-    const structurallyCleanSource = removeCommentOnlyAtRules(rawSource)
     if (options.lastCssResultByFile?.has(file)) {
+      const structurallyCleanSource = removeCommentOnlyAtRules(rawSource)
       const outputCss = stripMiniProgramCssSpecificityPlaceholders(structurallyCleanSource)
       if (outputCss !== rawSource) {
         plan.write(file, outputCss)
@@ -68,6 +68,7 @@ export async function finalizeMiniProgramCssAssets(
       continue
     }
     if (!shouldFinalizeMiniProgramCssAsset(rawSource)) {
+      const structurallyCleanSource = removeCommentOnlyAtRules(rawSource)
       if (structurallyCleanSource !== rawSource) {
         plan.write(file, structurallyCleanSource)
         writeTargets.set(file, output)
@@ -80,7 +81,7 @@ export async function finalizeMiniProgramCssAssets(
     }
 
     const cssHandlerOptions = options.getCssHandlerOptions(file)
-    const { css } = await options.styleHandler(structurallyCleanSource, {
+    const { css } = await options.styleHandler(rawSource, {
       ...cssHandlerOptions,
       autoprefixer: false,
       cssOptions: {

From ccab807ef1fb84c8ea575a261969594b1644ebca Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 13:11:40 +0800
Subject: [PATCH 04/13] fix(postcss): preserve incremental at-rule placeholders

---
 .../compat/mini-program-css/prune-generated.ts   |  8 ++++++--
 packages/postcss/src/plugins/post.ts             |  4 ----
 .../postcss/src/vite-css-rules/containment.ts    |  3 +--
 packages/postcss/src/vite-css-rules/coverage.ts  |  9 ++++++++-
 .../postcss/src/vite-css-rules/mini-program.ts   |  2 +-
 .../test/mini-program-generated-css.test.ts      | 11 +++--------
 .../vite/processed-css-assets/cleanup.ts         | 16 ++++++++++++++--
 7 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/packages/postcss/src/compat/mini-program-css/prune-generated.ts b/packages/postcss/src/compat/mini-program-css/prune-generated.ts
index 52ced8a74..f130708da 100644
--- a/packages/postcss/src/compat/mini-program-css/prune-generated.ts
+++ b/packages/postcss/src/compat/mini-program-css/prune-generated.ts
@@ -11,7 +11,7 @@ import {
   isPseudoContentInitRule,
   usesTwContentVariable,
 } from './predicates'
-import { removeEmptyAtRules, removeSpecificityPlaceholders, removeTailwindContainerMaxWidthMediaRules, removeTailwindContainerWidthRules, removeUnsupportedModernColorDeclarations } from './root-cleanups'
+import { removeSpecificityPlaceholders, removeTailwindContainerMaxWidthMediaRules, removeTailwindContainerWidthRules, removeUnsupportedModernColorDeclarations } from './root-cleanups'
 import { getRuleSelectors, isMiniProgramNativeElementSelector, isUnsupportedBrowserPreflightSelector, MINI_PROGRAM_ELEMENT_SCOPE_SELECTOR, MINI_PROGRAM_ELEMENT_SCOPE_SELECTORS } from './selectors'
 
 const DEFAULT_WEAPP_VARIABLE_SCOPE = 'page,.tw-root,wx-root-portal-content,:host'
@@ -310,7 +310,11 @@ export function pruneMiniProgramGeneratedCss(
     ensureMiniProgramElementContentInit(root)
   }
 
-  removeEmptyAtRules(root)
+  root.walkAtRules((atRule) => {
+    if (!atRule.nodes || atRule.nodes.length === 0) {
+      atRule.remove()
+    }
+  })
 
   return root.toString()
 }
diff --git a/packages/postcss/src/plugins/post.ts b/packages/postcss/src/plugins/post.ts
index 4dac29c38..b5fbc00dc 100644
--- a/packages/postcss/src/plugins/post.ts
+++ b/packages/postcss/src/plugins/post.ts
@@ -241,10 +241,6 @@ const postcssWeappTailwindcssPostPlugin: PostcssWeappTailwindcssRenamePlugin = (
         atRule.remove()
       }
     }
-
-    if (atRule.nodes?.every(node => node.type === 'comment')) {
-      atRule.remove()
-    }
   }
   return p
 }
diff --git a/packages/postcss/src/vite-css-rules/containment.ts b/packages/postcss/src/vite-css-rules/containment.ts
index 5a55924c1..4f1ab2794 100644
--- a/packages/postcss/src/vite-css-rules/containment.ts
+++ b/packages/postcss/src/vite-css-rules/containment.ts
@@ -1,6 +1,5 @@
-import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { postcss } from '../postcss-runtime'
-import { isCssRuleCoveredByDeclarations } from './coverage'
+import { isCssRuleCoveredByDeclarations, removeEmptyAtRules } from './coverage'
 import { collectCssRuleContentKeys, collectCssRuleDeclarationKeyMap, collectNormalizedCssNodes, getCssRuleContentKey, normalizeCssForContainment } from './structure'
 
 export function filterExistingCssRules(baseCss: string, css: string) {
diff --git a/packages/postcss/src/vite-css-rules/coverage.ts b/packages/postcss/src/vite-css-rules/coverage.ts
index a5b2468c2..d02e69777 100644
--- a/packages/postcss/src/vite-css-rules/coverage.ts
+++ b/packages/postcss/src/vite-css-rules/coverage.ts
@@ -1,4 +1,3 @@
-import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { postcss } from '../postcss-runtime'
 import { collectCssRuleDeclarationKeys, collectCssRuleDeclarationRecords, collectCssRuleDeclarations, getCssRuleStructuralKey, isCoveredByBaseVarFallbackDeclaration, isEquivalentVarFallbackDeclaration, normalizeCssDeclarationKey, normalizeCssForContainment, parseVarReferenceValue } from './structure'
 
@@ -171,3 +170,11 @@ export function mergeCoveredCssRuleDeclarations(baseCss: string, css: string) {
     return { baseCss, css, changed: false }
   }
 }
+
+export function removeEmptyAtRules(root: postcss.Root) {
+  root.walkAtRules((atRule) => {
+    if (atRule.nodes && atRule.nodes.every(node => node.type === 'comment')) {
+      atRule.remove()
+    }
+  })
+}
diff --git a/packages/postcss/src/vite-css-rules/mini-program.ts b/packages/postcss/src/vite-css-rules/mini-program.ts
index 2aae89a8b..598bcf591 100644
--- a/packages/postcss/src/vite-css-rules/mini-program.ts
+++ b/packages/postcss/src/vite-css-rules/mini-program.ts
@@ -1,7 +1,7 @@
 import type { Node, Selector } from 'postcss-selector-parser'
 import selectorParser from 'postcss-selector-parser'
-import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { postcss } from '../postcss-runtime'
+import { removeEmptyAtRules } from './coverage'
 import { collectCssRuleDeclarationRecords, collectCssRuleDeclarations, getCssRuleStructuralKeyWithSelectorKey, MINI_PROGRAM_PREFLIGHT_SELECTOR_KEY, MINI_PROGRAM_PREFLIGHT_SELECTOR_KEYS, MINI_PROGRAM_THEME_SCOPE_SELECTOR_KEY, MINI_PROGRAM_THEME_SCOPE_SELECTOR_KEYS, normalizeCssDeclarationKey } from './structure'
 
 function normalizeSimpleMiniProgramSelectorNode(node: Node) {
diff --git a/packages/postcss/test/mini-program-generated-css.test.ts b/packages/postcss/test/mini-program-generated-css.test.ts
index 60e47045b..ad5bcb413 100644
--- a/packages/postcss/test/mini-program-generated-css.test.ts
+++ b/packages/postcss/test/mini-program-generated-css.test.ts
@@ -107,18 +107,13 @@ describe('mini-program generated css cleanup', () => {
     expect(css).not.toContain('box-sizing:border-box')
   })
 
-  it('removes empty conditional at-rules from non-main mini-program chunks', async () => {
-    const styleHandler = createStyleHandler({
-      majorVersion: 4,
-    })
-    const { css } = await styleHandler([
+  it('removes empty conditional at-rules from generated mini-program css', () => {
+    const css = finalizeMiniProgramCss([
       '@media (prefers-color-scheme: light) {}',
       '@media (prefers-color-scheme: dark) { /* removed declarations */ }',
       '@media screen { @supports (display: grid) {} }',
       '.keep{color:red}',
-    ].join('\n'), {
-      isMainChunk: false,
-    })
+    ].join('\n'), { isTailwindcssV4: true })
 
     expect(css).not.toContain('@media')
     expect(css).not.toContain('@supports')
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
index 8173cf850..45dffcb38 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
@@ -1,7 +1,7 @@
 import type { OutputAsset, OutputBundle } from 'rollup'
 import type { CollectViteProcessedCssAssetOptions } from './markers-imports'
 import type { InternalUserDefinedOptions } from '@/types'
-import { isMiniProgramLocalCssImportRequest, parseTailwindCssDirectiveRequest, postcss, removeEmptyAtRules } from '@weapp-tailwindcss/postcss'
+import { isMiniProgramLocalCssImportRequest, parseTailwindCssDirectiveRequest, postcss } from '@weapp-tailwindcss/postcss'
 import path from 'pathe'
 import { normalizeOutputPathKey } from '../../shared/module-graph'
 import { appendCss, collectImportedStyleFiles, createCssAssetPipelineContext, getAssetFile, isStyleImportRequest, readAssetSource } from './markers-imports'
@@ -76,7 +76,19 @@ export function removeCommentOnlyAtRules(css: string) {
   }
   try {
     const root = postcss.parse(css)
-    return removeEmptyAtRules(root) > 0 ? root.toString() : css
+    let changed = false
+    let passChanged = true
+    while (passChanged) {
+      passChanged = false
+      root.walkAtRules((atRule) => {
+        if (!atRule.nodes || atRule.nodes.length === 0 || atRule.nodes.every(node => node.type === 'comment')) {
+          atRule.remove()
+          changed = true
+          passChanged = true
+        }
+      })
+    }
+    return changed ? root.toString() : css
   }
   catch {
     return css

From f9f284fd1a019a00b4f566792e0932b8d87b8791 Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 13:52:53 +0800
Subject: [PATCH 05/13] fix(vite): preserve cached css during hmr

---
 .../vite/generate-bundle/final-css-assets.ts  |  9 +++++--
 .../vite/generate-bundle/finalize/bundle.ts   |  1 +
 .../bundlers/vite-plugin.bundle.unit.test.ts  | 26 +++++++++++++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
index 77a8e6cf1..725ac5fda 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
@@ -31,6 +31,7 @@ export async function finalizeMiniProgramCssAssets(
     onUpdate: GenerateBundleContext['opts']['onUpdate']
     recordCssAssetResult: GenerateBundleContext['recordCssAssetResult']
     styleHandler: GenerateBundleContext['opts']['styleHandler']
+    useIncrementalMode?: boolean | undefined
     debug?: GenerateBundleContext['debug']
   },
 ) {
@@ -55,7 +56,9 @@ export async function finalizeMiniProgramCssAssets(
       continue
     }
     if (options.lastCssResultByFile?.has(file)) {
-      const structurallyCleanSource = removeCommentOnlyAtRules(rawSource)
+      const structurallyCleanSource = options.useIncrementalMode
+        ? rawSource
+        : removeCommentOnlyAtRules(rawSource)
       const outputCss = stripMiniProgramCssSpecificityPlaceholders(structurallyCleanSource)
       if (outputCss !== rawSource) {
         plan.write(file, outputCss)
@@ -68,7 +71,9 @@ export async function finalizeMiniProgramCssAssets(
       continue
     }
     if (!shouldFinalizeMiniProgramCssAsset(rawSource)) {
-      const structurallyCleanSource = removeCommentOnlyAtRules(rawSource)
+      const structurallyCleanSource = options.useIncrementalMode
+        ? rawSource
+        : removeCommentOnlyAtRules(rawSource)
       if (structurallyCleanSource !== rawSource) {
         plan.write(file, structurallyCleanSource)
         writeTargets.set(file, output)
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/finalize/bundle.ts b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/finalize/bundle.ts
index 18e05ba29..a0c1928db 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/finalize/bundle.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/finalize/bundle.ts
@@ -209,6 +209,7 @@ export async function finalizeGenerateBundle(options: FinalizeGenerateBundleOpti
     onUpdate,
     recordCssAssetResult,
     styleHandler,
+    useIncrementalMode,
   })
   recordTimingDetail('finalize.cssAssets', finalCssAssetsStartedAt)
   const webCompatStartedAt = performance.now()
diff --git a/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts b/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
index bcd691ea2..ca58ac800 100644
--- a/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
+++ b/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
@@ -15285,6 +15285,32 @@ page {
     expect(onUpdate).toHaveBeenCalledWith('app.wxss', expect.any(String), css)
   })
 
+  it('does not rewrite cached css assets during incremental finalization', async () => {
+    const { finalizeMiniProgramCssAssets } = await import('@/bundlers/vite/generate-bundle/final-css-assets')
+    const source = '@media (prefers-color-scheme: dark) {}\n.keep{color:red}'
+    const bundle = {
+      'app.wxss': {
+        ...createRollupAsset(source),
+        fileName: 'app.wxss',
+      },
+    }
+    const onUpdate = vi.fn()
+
+    await finalizeMiniProgramCssAssets(bundle, {
+      cssMatcher: file => file.endsWith('.wxss'),
+      getCssHandlerOptions: () => ({ isMainChunk: true } as any),
+      isWebGeneratorTarget: false,
+      lastCssResultByFile: new Map([['app.wxss', 'cached']]),
+      onUpdate,
+      recordCssAssetResult: vi.fn(),
+      styleHandler: vi.fn(async (code: string) => ({ css: code })),
+      useIncrementalMode: true,
+    })
+
+    expect((bundle['app.wxss'] as OutputAsset).source.toString()).toBe(source)
+    expect(onUpdate).not.toHaveBeenCalled()
+  })
+
   it('logs css diffs when vite css diff debugging is enabled', async () => {
     const previousDebugCssDiff = process.env.WEAPP_TW_VITE_DEBUG_CSS_DIFF
     process.env.WEAPP_TW_VITE_DEBUG_CSS_DIFF = '1'

From 946bc1a926e50060b0806d7a584767eb7c15cf42 Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 14:14:11 +0800
Subject: [PATCH 06/13] fix(postcss): preserve incremental media containers

---
 .../compat/mini-program-css/finalize-options.ts |  7 +++++++
 .../src/compat/mini-program-css/finalize.ts     | 11 ++++++++++-
 packages/postcss/test/mini-program-css.test.ts  | 17 +++++++++++++++++
 .../generation-helpers/preflight.ts             |  9 ++++++++-
 .../shared/generator-css/pipeline/context.ts    |  1 +
 .../generator-css/pipeline/ordered-output.ts    |  1 +
 .../test/bundlers/generator-css.unit.test.ts    | 10 ++++++++++
 7 files changed, 54 insertions(+), 2 deletions(-)

diff --git a/packages/postcss/src/compat/mini-program-css/finalize-options.ts b/packages/postcss/src/compat/mini-program-css/finalize-options.ts
index b96c4b455..d3e234beb 100644
--- a/packages/postcss/src/compat/mini-program-css/finalize-options.ts
+++ b/packages/postcss/src/compat/mini-program-css/finalize-options.ts
@@ -4,6 +4,13 @@ export interface FinalizeMiniProgramCssOptions {
   cssPreflight?: CssPreflightOptions | undefined
   cssSelectorReplacement?: CssSelectorReplacement | undefined
   isTailwindcssV4?: boolean | undefined
+  /**
+   * 是否递归移除子规则被清理而变空的父级条件规则。
+   *
+   * 增量生成的 CSS 可能只包含条件规则中的新片段，父级容器由已缓存产物提供，
+   * 此时应保留占位容器，避免后续追加 CSS 时丢失层级。
+   */
+  removeEmptyAtRuleAncestors?: boolean | undefined
   /**
    * 是否为 Tailwind CSS v4 渐变工具类生成小程序字面量兜底。
    */
diff --git a/packages/postcss/src/compat/mini-program-css/finalize.ts b/packages/postcss/src/compat/mini-program-css/finalize.ts
index 6386f9389..a7714be66 100644
--- a/packages/postcss/src/compat/mini-program-css/finalize.ts
+++ b/packages/postcss/src/compat/mini-program-css/finalize.ts
@@ -80,7 +80,16 @@ function finalizeMiniProgramCssRoot(root: postcss.Root, options: FinalizeMiniPro
   const themeRule = collectThemeVariableRule(root, options)
   const hoistedRules = themeRule ? [...preflightRules, themeRule] : preflightRules
   insertHoistedRules(root, mergeEquivalentHoistedRules(hoistedRules), hoistAnchor)
-  removeEmptyAtRules(root)
+  if (options.removeEmptyAtRuleAncestors !== false) {
+    removeEmptyAtRules(root)
+  }
+  else {
+    root.walkAtRules((atRule) => {
+      if (atRule.nodes?.length === 0) {
+        atRule.remove()
+      }
+    })
+  }
 }
 
 export function hoistTailwindPreflightBase(css: string) {
diff --git a/packages/postcss/test/mini-program-css.test.ts b/packages/postcss/test/mini-program-css.test.ts
index d48097455..0eb4dd7f7 100644
--- a/packages/postcss/test/mini-program-css.test.ts
+++ b/packages/postcss/test/mini-program-css.test.ts
@@ -681,6 +681,23 @@ describe('mini-program css cleanup', () => {
     expect(css).not.toContain('margin')
   })
 
+  it('keeps incremental at-rule ancestors when recursive cleanup is disabled', () => {
+    const css = finalizeMiniProgramCss('@media screen{/* incremental placeholder */}', {
+      cssPreflight: false,
+      removeEmptyAtRuleAncestors: false,
+    })
+
+    expect(css).toBe('@media screen{/* incremental placeholder */}')
+  })
+
+  it('recursively removes empty at-rule ancestors for complete css output', () => {
+    const css = finalizeMiniProgramCss('@media screen{@supports (display:grid){}}', {
+      cssPreflight: false,
+    })
+
+    expect(css).toBe('')
+  })
+
   it('prunes browser-only generated css while preserving useful mini-program selectors', () => {
     const css = pruneMiniProgramGeneratedCss([
       '/* #ifdef MP-WEIXIN */',
diff --git a/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/generation-helpers/preflight.ts b/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/generation-helpers/preflight.ts
index e43429086..f86dbbecf 100644
--- a/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/generation-helpers/preflight.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/generation-helpers/preflight.ts
@@ -18,7 +18,12 @@ export function finalizeMiniProgramGeneratorCss(
   target: string,
   _majorVersion: number | undefined,
   cssPreflight: InternalUserDefinedOptions['cssPreflight'],
-  options: { injectPreflight?: boolean, preservePreflight?: boolean, styleOptions?: Partial<IStyleHandlerOptions> | undefined } = {},
+  options: {
+    injectPreflight?: boolean | undefined
+    preservePreflight?: boolean | undefined
+    removeEmptyAtRuleAncestors?: boolean | undefined
+    styleOptions?: Partial<IStyleHandlerOptions> | undefined
+  } = {},
 ) {
   if (!isMiniProgramGeneratorTarget(target)) {
     return css
@@ -29,6 +34,7 @@ export function finalizeMiniProgramGeneratorCss(
       cssSelectorReplacement: options.styleOptions?.cssOptions?.cssSelectorReplacement
         ?? options.styleOptions?.cssSelectorReplacement,
       isTailwindcssV4: true,
+      removeEmptyAtRuleAncestors: options.removeEmptyAtRuleAncestors,
       tailwindcssV4GradientFallback: options.styleOptions?.cssOptions?.tailwindcssV4GradientFallback
         ?? options.styleOptions?.tailwindcssV4GradientFallback,
     })
@@ -48,6 +54,7 @@ export function finalizeMiniProgramGeneratorCss(
     cssSelectorReplacement: options.styleOptions?.cssOptions?.cssSelectorReplacement
       ?? options.styleOptions?.cssSelectorReplacement,
     isTailwindcssV4: true,
+    removeEmptyAtRuleAncestors: options.removeEmptyAtRuleAncestors,
     tailwindcssV4GradientFallback: options.styleOptions?.cssOptions?.tailwindcssV4GradientFallback
       ?? options.styleOptions?.tailwindcssV4GradientFallback,
   })
diff --git a/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/pipeline/context.ts b/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/pipeline/context.ts
index 546c87f0d..ad00c100f 100644
--- a/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/pipeline/context.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/pipeline/context.ts
@@ -15,6 +15,7 @@ export interface GeneratorPipelineExecutionContext {
     options?: {
       injectPreflight?: boolean | undefined
       preservePreflight?: boolean | undefined
+      removeEmptyAtRuleAncestors?: boolean | undefined
       styleOptions?: Partial<IStyleHandlerOptions> | undefined
     },
   ) => string
diff --git a/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/pipeline/ordered-output.ts b/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/pipeline/ordered-output.ts
index 5ef6f8070..9a9eea958 100644
--- a/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/pipeline/ordered-output.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/shared/generator-css/pipeline/ordered-output.ts
@@ -21,6 +21,7 @@ export async function finalizeOrderedGeneratorCss(
     const css = incrementalCss.trim().length > 0
       ? finalizeIncrementalGeneratorCss(options.previousCss, incrementalCss, generated.target, majorVersion, opts.cssPreflight, {
           injectPreflight: false,
+          removeEmptyAtRuleAncestors: false,
           styleOptions: generatorStyleOptions,
         }, generatorOptions.webCompat)
       : options.previousCss
diff --git a/packages/weapp-tailwindcss/test/bundlers/generator-css.unit.test.ts b/packages/weapp-tailwindcss/test/bundlers/generator-css.unit.test.ts
index 7b7ac370b..50763a9db 100644
--- a/packages/weapp-tailwindcss/test/bundlers/generator-css.unit.test.ts
+++ b/packages/weapp-tailwindcss/test/bundlers/generator-css.unit.test.ts
@@ -9899,6 +9899,16 @@ describe('bundlers/shared generator css', () => {
     expect(css).toContain('background-image:linear-gradient(to right, #06b6d4, #3b82f6)')
   })
 
+  it('preserves incremental at-rule placeholders during generator finalization', async () => {
+    const { finalizeMiniProgramGeneratorCss } = await import('@/bundlers/shared/generator-css/generation-helpers')
+    const css = finalizeMiniProgramGeneratorCss('@media screen{/* incremental placeholder */}', 'weapp', 4, false, {
+      injectPreflight: false,
+      removeEmptyAtRuleAncestors: false,
+    })
+
+    expect(css).toBe('@media screen{/* incremental placeholder */}')
+  })
+
   it('does not inject Tailwind v4 mini-program preflight twice when generator css already has reset', async () => {
     const { finalizeMiniProgramGeneratorCss } = await import('@/bundlers/shared/generator-css/generation-helpers')
     const css = finalizeMiniProgramGeneratorCss([

From 8b87235f9f982775c504b975fe7ba7e13d9fa638 Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 14:25:06 +0800
Subject: [PATCH 07/13] fix(postcss): remove empty media after selector cleanup

---
 packages/postcss/src/plugins/post.ts | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/postcss/src/plugins/post.ts b/packages/postcss/src/plugins/post.ts
index b5fbc00dc..48668ed3b 100644
--- a/packages/postcss/src/plugins/post.ts
+++ b/packages/postcss/src/plugins/post.ts
@@ -2,6 +2,7 @@
 import type { Declaration, Plugin, PluginCreator, Root, Rule } from 'postcss'
 import type { IStyleHandlerOptions } from '../types'
 import { defu } from '@weapp-tailwindcss/shared'
+import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { getRuleSelectors, isMiniProgramThemeScopeSelector, MINI_PROGRAM_ELEMENT_SCOPE_SELECTOR } from '../compat/mini-program-css/selectors'
 import { normalizeMiniProgramPrefixedDeclaration, removeUnsupportedMiniProgramPrefixedAtRule } from '../compat/mini-program-prefixes'
 import { normalizeTailwindcssRpxDeclaration } from '../compat/tailwindcss-rpx'
@@ -226,6 +227,9 @@ const postcssWeappTailwindcssPostPlugin: PostcssWeappTailwindcssRenamePlugin = (
     if (shouldInjectTailwindcssV4Defaults || (opts.majorVersion === 4 && usesTailwindcssV4ContentVariable(root))) {
       injectMissingTailwindcssV4Defaults(root)
     }
+    if (enableMainChunkTransforms) {
+      removeEmptyAtRules(root)
+    }
   }
 
   p.AtRuleExit = (atRule) => {

From 17f1f07c669a0e1e3a4e2ad0fd678b55be16dae2 Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 15:30:36 +0800
Subject: [PATCH 08/13] fix(vite): preserve css import at-rules during cleanup

---
 .../src/bundlers/vite/processed-css-assets/cleanup.ts           | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
index 45dffcb38..001b42102 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
@@ -81,7 +81,7 @@ export function removeCommentOnlyAtRules(css: string) {
     while (passChanged) {
       passChanged = false
       root.walkAtRules((atRule) => {
-        if (!atRule.nodes || atRule.nodes.length === 0 || atRule.nodes.every(node => node.type === 'comment')) {
+        if (atRule.nodes && (atRule.nodes.length === 0 || atRule.nodes.every(node => node.type === 'comment'))) {
           atRule.remove()
           changed = true
           passChanged = true

From 3c8789fc85dfad707d9d8f535e56ce1fd51af8d3 Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 16:20:56 +0800
Subject: [PATCH 09/13] fix(vite): avoid incremental css append in framework
 watch

---
 .../vite/shared/create-framework-plugins-runtime.ts      | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/shared/create-framework-plugins-runtime.ts b/packages/weapp-tailwindcss/src/bundlers/vite/shared/create-framework-plugins-runtime.ts
index cd9612954..12d8158d0 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/shared/create-framework-plugins-runtime.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/shared/create-framework-plugins-runtime.ts
@@ -361,10 +361,15 @@ ${previousTracedCss}`
     const cssHandlerOptions = { ...sourceCssHandlerOptions, isMainChunk: outputCssHandlerOptions.isMainChunk }
     const transientCssSource = transientAutoCssSources.get(file) ?? (hasTailwindRootDirectives(generatorTransformCode, { importFallback: currentGeneratorOptions.importFallback }) || hasTailwindSourceDirectives(generatorTransformCode, { importFallback: currentGeneratorOptions.importFallback }) || hasTailwindApplyDirective(generatorTransformCode) ? { base: path.dirname(path.resolve(file)), css: generatorTransformCode, file: path.resolve(file) } : void 0)
     const shouldDeferEmptyScopedCssSource = transientCssSource == null && (frameworkCssPipelineStrategy?.shouldDeferEmptyScopedCssSource?.({ ...cssPipelineContext, cssHandlerOptions, generatorCode: generatorTransformCode }) ?? true)
-    const previousCss = pendingHmrChange && !forceFullHmrCssRegeneration ? cleanGeneratedCssByFile.get(fileKey) : void 0
+    const shouldBypassIncrementalCssAppend = pendingHmrChange !== void 0
+      && !currentGeneratorBranch.isWeb
+      && (opts.appType === 'taro' || opts.appType === 'uni-app-vite')
+    const previousCss = pendingHmrChange && !forceFullHmrCssRegeneration && !shouldBypassIncrementalCssAppend
+      ? cleanGeneratedCssByFile.get(fileKey)
+      : void 0
     const previousGeneratorCss = previousCss && !currentGeneratorBranch.isWeb ? normalizeMiniProgramGeneratorCssSource(previousCss, outputFile) : previousCss
     const hmrDebugState = hmrCandidateState.snapshotDebugState()
-    const generated = await hmrTimingRecorder.measure(`generateCss.${resolvedConfig?.command ?? 'unknown'}`, () => generateTailwindV4Css({ opts, runtimeState, runtime, rawSource: generatorTransformCode, file, outputFile, cssHandlerOptions, cssUserHandlerOptions: transformCssHandlerOptions.getCssUserHandlerOptions(requestFile), cssSources: transientCssSource ? [transientCssSource] : void 0, getSourceCandidatesForEntries, generatorPlatform: resolveGeneratorPlatform(), styleHandler, debug, previousCss: previousGeneratorCss, previousClassSet: pendingHmrChange && !forceFullHmrCssRegeneration ? generatedClassSetByFile.get(fileKey) : void 0, deferEmptyScopedCssSource: shouldDeferEmptyScopedCssSource, deferCssAdaptation: !currentGeneratorBranch.isWeb && !shouldAdaptFrameworkWatchCss(), disableSourceScan: false, cssStage: hookContext?.cssStage, restoreLocalCssImports: !currentGeneratorBranch.isWeb }), { file, memoryDebug: { cleanCacheHit: cleanGeneratedCssByFile.has(fileKey), forceFullHmrCssRegeneration, ...hmrDebugState, pendingResolved: pendingHmrChange !== void 0, runtimeCandidates: runtime.size, target: currentGeneratorOptions.target } })
+    const generated = await hmrTimingRecorder.measure(`generateCss.${resolvedConfig?.command ?? 'unknown'}`, () => generateTailwindV4Css({ opts, runtimeState, runtime, rawSource: generatorTransformCode, file, outputFile, cssHandlerOptions, cssUserHandlerOptions: transformCssHandlerOptions.getCssUserHandlerOptions(requestFile), cssSources: transientCssSource ? [transientCssSource] : void 0, getSourceCandidatesForEntries, generatorPlatform: resolveGeneratorPlatform(), styleHandler, debug, previousCss: previousGeneratorCss, previousClassSet: pendingHmrChange && !forceFullHmrCssRegeneration && !shouldBypassIncrementalCssAppend ? generatedClassSetByFile.get(fileKey) : void 0, deferEmptyScopedCssSource: shouldDeferEmptyScopedCssSource, deferCssAdaptation: !currentGeneratorBranch.isWeb && !shouldAdaptFrameworkWatchCss(), disableSourceScan: false, cssStage: hookContext?.cssStage, restoreLocalCssImports: !currentGeneratorBranch.isWeb }), { file, memoryDebug: { cleanCacheHit: cleanGeneratedCssByFile.has(fileKey), forceFullHmrCssRegeneration, ...hmrDebugState, pendingResolved: pendingHmrChange !== void 0, runtimeCandidates: runtime.size, target: currentGeneratorOptions.target } })
     if (!generated) {
       if (pendingHmrChange) {
         hmrCandidateState.finishTarget(file)

From 0b6084145b6c88b5230d15a4167ef17ae3d4c88b Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 16:45:58 +0800
Subject: [PATCH 10/13] fix(vite): regenerate framework css during watch replay

---
 .../vite/generate-bundle/remembered-css-replay.ts        | 3 ++-
 .../vite/shared/create-framework-plugins-runtime.ts      | 9 ++-------
 .../test/bundlers/vite-plugin.bundle.unit.test.ts        | 8 ++++----
 3 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/remembered-css-replay.ts b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/remembered-css-replay.ts
index 5fb763c15..d52164a50 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/remembered-css-replay.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/remembered-css-replay.ts
@@ -195,7 +195,8 @@ export async function processRememberedCssReplay(options: ProcessRememberedCssRe
     const cssSourceChanged = changedCssFiles.has(outputFile)
       || changedCssFiles.has(sourceFile)
       || (previousRawSourceHash != null && previousRawSourceHash !== rawSourceHash)
-    const previousCss = useIncrementalMode && !cssSourceChanged && getLastCssSourceHash(lastCssSourceHashByFile, outputFile) === cssRuntimeAffectingHash
+    const canAppendIncrementalCss = opts.appType !== 'taro' && opts.appType !== 'uni-app-vite'
+    const previousCss = useIncrementalMode && canAppendIncrementalCss && !cssSourceChanged && getLastCssSourceHash(lastCssSourceHashByFile, outputFile) === cssRuntimeAffectingHash
       ? getLastCssResult(lastCssResultByFile, outputFile)
       : undefined
     const allRememberedSignaturesFresh = rememberedKeys.length > 0
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/shared/create-framework-plugins-runtime.ts b/packages/weapp-tailwindcss/src/bundlers/vite/shared/create-framework-plugins-runtime.ts
index 12d8158d0..cd9612954 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/shared/create-framework-plugins-runtime.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/shared/create-framework-plugins-runtime.ts
@@ -361,15 +361,10 @@ ${previousTracedCss}`
     const cssHandlerOptions = { ...sourceCssHandlerOptions, isMainChunk: outputCssHandlerOptions.isMainChunk }
     const transientCssSource = transientAutoCssSources.get(file) ?? (hasTailwindRootDirectives(generatorTransformCode, { importFallback: currentGeneratorOptions.importFallback }) || hasTailwindSourceDirectives(generatorTransformCode, { importFallback: currentGeneratorOptions.importFallback }) || hasTailwindApplyDirective(generatorTransformCode) ? { base: path.dirname(path.resolve(file)), css: generatorTransformCode, file: path.resolve(file) } : void 0)
     const shouldDeferEmptyScopedCssSource = transientCssSource == null && (frameworkCssPipelineStrategy?.shouldDeferEmptyScopedCssSource?.({ ...cssPipelineContext, cssHandlerOptions, generatorCode: generatorTransformCode }) ?? true)
-    const shouldBypassIncrementalCssAppend = pendingHmrChange !== void 0
-      && !currentGeneratorBranch.isWeb
-      && (opts.appType === 'taro' || opts.appType === 'uni-app-vite')
-    const previousCss = pendingHmrChange && !forceFullHmrCssRegeneration && !shouldBypassIncrementalCssAppend
-      ? cleanGeneratedCssByFile.get(fileKey)
-      : void 0
+    const previousCss = pendingHmrChange && !forceFullHmrCssRegeneration ? cleanGeneratedCssByFile.get(fileKey) : void 0
     const previousGeneratorCss = previousCss && !currentGeneratorBranch.isWeb ? normalizeMiniProgramGeneratorCssSource(previousCss, outputFile) : previousCss
     const hmrDebugState = hmrCandidateState.snapshotDebugState()
-    const generated = await hmrTimingRecorder.measure(`generateCss.${resolvedConfig?.command ?? 'unknown'}`, () => generateTailwindV4Css({ opts, runtimeState, runtime, rawSource: generatorTransformCode, file, outputFile, cssHandlerOptions, cssUserHandlerOptions: transformCssHandlerOptions.getCssUserHandlerOptions(requestFile), cssSources: transientCssSource ? [transientCssSource] : void 0, getSourceCandidatesForEntries, generatorPlatform: resolveGeneratorPlatform(), styleHandler, debug, previousCss: previousGeneratorCss, previousClassSet: pendingHmrChange && !forceFullHmrCssRegeneration && !shouldBypassIncrementalCssAppend ? generatedClassSetByFile.get(fileKey) : void 0, deferEmptyScopedCssSource: shouldDeferEmptyScopedCssSource, deferCssAdaptation: !currentGeneratorBranch.isWeb && !shouldAdaptFrameworkWatchCss(), disableSourceScan: false, cssStage: hookContext?.cssStage, restoreLocalCssImports: !currentGeneratorBranch.isWeb }), { file, memoryDebug: { cleanCacheHit: cleanGeneratedCssByFile.has(fileKey), forceFullHmrCssRegeneration, ...hmrDebugState, pendingResolved: pendingHmrChange !== void 0, runtimeCandidates: runtime.size, target: currentGeneratorOptions.target } })
+    const generated = await hmrTimingRecorder.measure(`generateCss.${resolvedConfig?.command ?? 'unknown'}`, () => generateTailwindV4Css({ opts, runtimeState, runtime, rawSource: generatorTransformCode, file, outputFile, cssHandlerOptions, cssUserHandlerOptions: transformCssHandlerOptions.getCssUserHandlerOptions(requestFile), cssSources: transientCssSource ? [transientCssSource] : void 0, getSourceCandidatesForEntries, generatorPlatform: resolveGeneratorPlatform(), styleHandler, debug, previousCss: previousGeneratorCss, previousClassSet: pendingHmrChange && !forceFullHmrCssRegeneration ? generatedClassSetByFile.get(fileKey) : void 0, deferEmptyScopedCssSource: shouldDeferEmptyScopedCssSource, deferCssAdaptation: !currentGeneratorBranch.isWeb && !shouldAdaptFrameworkWatchCss(), disableSourceScan: false, cssStage: hookContext?.cssStage, restoreLocalCssImports: !currentGeneratorBranch.isWeb }), { file, memoryDebug: { cleanCacheHit: cleanGeneratedCssByFile.has(fileKey), forceFullHmrCssRegeneration, ...hmrDebugState, pendingResolved: pendingHmrChange !== void 0, runtimeCandidates: runtime.size, target: currentGeneratorOptions.target } })
     if (!generated) {
       if (pendingHmrChange) {
         hmrCandidateState.finishTarget(file)
diff --git a/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts b/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
index ca58ac800..65d58a2ac 100644
--- a/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
+++ b/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
@@ -7531,7 +7531,7 @@ module.exports = {
     expect(viteProcessedCssAssetResults.get(subSourceFile)?.injectIntoMain).toBe(false)
   }, TEST_TIMEOUT_MS)
 
-  it('passes previous css to unchanged remembered vite css replay', async () => {
+  it('regenerates complete css for unchanged uni-app vite css replay', async () => {
     const generateCalls: Array<{
       rawSource: string
       previousCss?: string | undefined
@@ -7544,8 +7544,8 @@ module.exports = {
         rawSource: options.rawSource,
         previousCss: options.previousCss,
       })
-      const css = options.previousCss
-        ? `${options.previousCss}\n.tw-replay-next{display:flex}`
+      const css = generateCalls.length > 1
+        ? '.tw-replay-base{display:block}\n.tw-replay-next{display:flex}'
         : '.tw-replay-base{display:block}'
       return {
         css,
@@ -7664,7 +7664,7 @@ module.exports = {
 
     expect(generateCalls).toHaveLength(2)
     expect(generateCalls[0]?.previousCss).toBeUndefined()
-    expect(generateCalls[1]?.previousCss).toBe(firstCss)
+    expect(generateCalls[1]?.previousCss).toBeUndefined()
     expect(pruneViteCssCaches).toHaveBeenCalledTimes(1)
     const firstPruneOptions = pruneViteCssCaches.mock.calls.at(0)?.[0]
     expect(firstPruneOptions.activeFiles.has('pages/index/index.wxss')).toBe(true)

From c85234960ab59bdda359e2ab7f6be197f9418979 Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 17:11:09 +0800
Subject: [PATCH 11/13] fix(vite): separate incremental and final at-rule
 cleanup

---
 .../vite/generate-bundle/final-css-assets.ts  |  6 ++--
 .../generate-bundle/remembered-css-replay.ts  |  3 +-
 .../vite/processed-css-assets/cleanup.ts      | 33 ++++++++++++-------
 .../bundlers/vite-plugin.bundle.unit.test.ts  |  8 ++---
 4 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
index 725ac5fda..4eced3283 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/final-css-assets.ts
@@ -6,7 +6,7 @@ import {
   stripMiniProgramCssSpecificityPlaceholders,
 } from '@/bundlers/shared/css-cleanup'
 import { AssetEmissionPlan } from '@/compiler'
-import { removeCommentOnlyAtRules } from '../processed-css-assets/cleanup'
+import { removeEmptyCssAtRules } from '../processed-css-assets/cleanup'
 import { applyViteAssetEmissionPlan } from './asset-emission-plan'
 
 function readAssetSource(output: OutputAsset) {
@@ -58,7 +58,7 @@ export async function finalizeMiniProgramCssAssets(
     if (options.lastCssResultByFile?.has(file)) {
       const structurallyCleanSource = options.useIncrementalMode
         ? rawSource
-        : removeCommentOnlyAtRules(rawSource)
+        : removeEmptyCssAtRules(rawSource)
       const outputCss = stripMiniProgramCssSpecificityPlaceholders(structurallyCleanSource)
       if (outputCss !== rawSource) {
         plan.write(file, outputCss)
@@ -73,7 +73,7 @@ export async function finalizeMiniProgramCssAssets(
     if (!shouldFinalizeMiniProgramCssAsset(rawSource)) {
       const structurallyCleanSource = options.useIncrementalMode
         ? rawSource
-        : removeCommentOnlyAtRules(rawSource)
+        : removeEmptyCssAtRules(rawSource)
       if (structurallyCleanSource !== rawSource) {
         plan.write(file, structurallyCleanSource)
         writeTargets.set(file, output)
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/remembered-css-replay.ts b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/remembered-css-replay.ts
index d52164a50..5fb763c15 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/remembered-css-replay.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/generate-bundle/remembered-css-replay.ts
@@ -195,8 +195,7 @@ export async function processRememberedCssReplay(options: ProcessRememberedCssRe
     const cssSourceChanged = changedCssFiles.has(outputFile)
       || changedCssFiles.has(sourceFile)
       || (previousRawSourceHash != null && previousRawSourceHash !== rawSourceHash)
-    const canAppendIncrementalCss = opts.appType !== 'taro' && opts.appType !== 'uni-app-vite'
-    const previousCss = useIncrementalMode && canAppendIncrementalCss && !cssSourceChanged && getLastCssSourceHash(lastCssSourceHashByFile, outputFile) === cssRuntimeAffectingHash
+    const previousCss = useIncrementalMode && !cssSourceChanged && getLastCssSourceHash(lastCssSourceHashByFile, outputFile) === cssRuntimeAffectingHash
       ? getLastCssResult(lastCssResultByFile, outputFile)
       : undefined
     const allRememberedSignaturesFresh = rememberedKeys.length > 0
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
index 001b42102..7a03143c8 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
@@ -1,7 +1,7 @@
 import type { OutputAsset, OutputBundle } from 'rollup'
 import type { CollectViteProcessedCssAssetOptions } from './markers-imports'
 import type { InternalUserDefinedOptions } from '@/types'
-import { isMiniProgramLocalCssImportRequest, parseTailwindCssDirectiveRequest, postcss } from '@weapp-tailwindcss/postcss'
+import { isMiniProgramLocalCssImportRequest, parseTailwindCssDirectiveRequest, postcss, removeEmptyAtRules } from '@weapp-tailwindcss/postcss'
 import path from 'pathe'
 import { normalizeOutputPathKey } from '../../shared/module-graph'
 import { appendCss, collectImportedStyleFiles, createCssAssetPipelineContext, getAssetFile, isStyleImportRequest, readAssetSource } from './markers-imports'
@@ -77,17 +77,13 @@ export function removeCommentOnlyAtRules(css: string) {
   try {
     const root = postcss.parse(css)
     let changed = false
-    let passChanged = true
-    while (passChanged) {
-      passChanged = false
-      root.walkAtRules((atRule) => {
-        if (atRule.nodes && (atRule.nodes.length === 0 || atRule.nodes.every(node => node.type === 'comment'))) {
-          atRule.remove()
-          changed = true
-          passChanged = true
-        }
-      })
-    }
+    root.walkAtRules((atRule) => {
+      if (!atRule.nodes || atRule.nodes.length === 0 || atRule.nodes.some(node => node.type !== 'comment')) {
+        return
+      }
+      atRule.remove()
+      changed = true
+    })
     return changed ? root.toString() : css
   }
   catch {
@@ -95,6 +91,19 @@ export function removeCommentOnlyAtRules(css: string) {
   }
 }
 
+export function removeEmptyCssAtRules(css: string) {
+  if (!css.includes('@') || !/@[a-z-]+\b[^{};]*\{(?:\s|\/\*[\s\S]*?\*\/)*\}/i.test(css)) {
+    return css
+  }
+  try {
+    const root = postcss.parse(css)
+    return removeEmptyAtRules(root) > 0 ? root.toString() : css
+  }
+  catch {
+    return css
+  }
+}
+
 export function collectImportedBundleCssSources(bundle: OutputBundle, importedStyleFiles: Set<string>) {
   if (importedStyleFiles.size === 0) {
     return []
diff --git a/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts b/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
index 65d58a2ac..ca58ac800 100644
--- a/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
+++ b/packages/weapp-tailwindcss/test/bundlers/vite-plugin.bundle.unit.test.ts
@@ -7531,7 +7531,7 @@ module.exports = {
     expect(viteProcessedCssAssetResults.get(subSourceFile)?.injectIntoMain).toBe(false)
   }, TEST_TIMEOUT_MS)
 
-  it('regenerates complete css for unchanged uni-app vite css replay', async () => {
+  it('passes previous css to unchanged remembered vite css replay', async () => {
     const generateCalls: Array<{
       rawSource: string
       previousCss?: string | undefined
@@ -7544,8 +7544,8 @@ module.exports = {
         rawSource: options.rawSource,
         previousCss: options.previousCss,
       })
-      const css = generateCalls.length > 1
-        ? '.tw-replay-base{display:block}\n.tw-replay-next{display:flex}'
+      const css = options.previousCss
+        ? `${options.previousCss}\n.tw-replay-next{display:flex}`
         : '.tw-replay-base{display:block}'
       return {
         css,
@@ -7664,7 +7664,7 @@ module.exports = {
 
     expect(generateCalls).toHaveLength(2)
     expect(generateCalls[0]?.previousCss).toBeUndefined()
-    expect(generateCalls[1]?.previousCss).toBeUndefined()
+    expect(generateCalls[1]?.previousCss).toBe(firstCss)
     expect(pruneViteCssCaches).toHaveBeenCalledTimes(1)
     const firstPruneOptions = pruneViteCssCaches.mock.calls.at(0)?.[0]
     expect(firstPruneOptions.activeFiles.has('pages/index/index.wxss')).toBe(true)

From a8e65a5f0048e127f462641fdb777c36a72a8116 Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 18:53:44 +0800
Subject: [PATCH 12/13] fix(postcss): avoid regex backtracking during at-rule
 cleanup

---
 .../compat/mini-program-css/root-cleanups.ts  | 11 +++++
 packages/postcss/src/handler.ts               | 14 +++++++
 packages/postcss/src/plugins/post.ts          | 12 +++---
 packages/postcss/test/post.test.ts            | 31 ++++++++++++++
 .../vite/processed-css-assets/cleanup.ts      | 18 +++++++--
 .../vite-processed-css-cleanup.unit.test.ts   | 40 +++++++++++++++++++
 6 files changed, 116 insertions(+), 10 deletions(-)
 create mode 100644 packages/weapp-tailwindcss/test/bundlers/vite-processed-css-cleanup.unit.test.ts

diff --git a/packages/postcss/src/compat/mini-program-css/root-cleanups.ts b/packages/postcss/src/compat/mini-program-css/root-cleanups.ts
index 36f607cfd..ebe2df3ac 100644
--- a/packages/postcss/src/compat/mini-program-css/root-cleanups.ts
+++ b/packages/postcss/src/compat/mini-program-css/root-cleanups.ts
@@ -98,6 +98,17 @@ export function removeEmptyAtRules(root: postcss.Root) {
   return removed
 }
 
+export function removeEmptyBlockAtRules(root: postcss.Root) {
+  let removed = 0
+  root.walkAtRules((atRule) => {
+    if (atRule.nodes?.length === 0) {
+      atRule.remove()
+      removed++
+    }
+  })
+  return removed
+}
+
 function removeEmptyAtRuleAncestors(parent: postcss.Container | undefined) {
   while (parent?.type === 'atrule' && isEffectivelyEmptyContainer(parent)) {
     const nextParent = parent.parent
diff --git a/packages/postcss/src/handler.ts b/packages/postcss/src/handler.ts
index 93ffa903d..01be9fbe5 100644
--- a/packages/postcss/src/handler.ts
+++ b/packages/postcss/src/handler.ts
@@ -6,6 +6,7 @@ import { defuOverrideArray } from '@weapp-tailwindcss/shared'
 import { LRUCache } from 'lru-cache'
 import postcss from 'postcss'
 import { protectDynamicColorMixAlpha } from './compat/color-mix'
+import { removeEmptyBlockAtRules } from './compat/mini-program-css/root-cleanups'
 import { probeFeatures, signalToCacheKey } from './content-probe'
 import { getDefaultOptions } from './defaults'
 import { fingerprintOptions } from './fingerprint'
@@ -128,6 +129,19 @@ export function createStyleHandler(options?: Partial<IStyleHandlerOptions>): Sty
     ).async().then((result) => {
       const styleBranch = resolvePostcssFrameworkProfile(resolvedOptions)
       let finalResult = styleBranch.postprocess(result, resolvedOptions)
+      if (resolvedOptions.isMainChunk !== false && finalResult.root) {
+        let removed = 0
+        let removedTotal = 0
+        do {
+          removed = removeEmptyBlockAtRules(finalResult.root)
+          removedTotal += removed
+        } while (removed > 0)
+        if (removedTotal > 0) {
+          const nextResult = finalResult.root.toResult(finalResult.opts)
+          nextResult.messages.push(...finalResult.messages)
+          finalResult = nextResult
+        }
+      }
       if (protectedColorMix) {
         const restoredCss = protectedColorMix.restore(finalResult.css)
         if (restoredCss !== finalResult.css) {
diff --git a/packages/postcss/src/plugins/post.ts b/packages/postcss/src/plugins/post.ts
index 48668ed3b..7ccc6a3eb 100644
--- a/packages/postcss/src/plugins/post.ts
+++ b/packages/postcss/src/plugins/post.ts
@@ -2,7 +2,6 @@
 import type { Declaration, Plugin, PluginCreator, Root, Rule } from 'postcss'
 import type { IStyleHandlerOptions } from '../types'
 import { defu } from '@weapp-tailwindcss/shared'
-import { removeEmptyAtRules } from '../compat/mini-program-css/root-cleanups'
 import { getRuleSelectors, isMiniProgramThemeScopeSelector, MINI_PROGRAM_ELEMENT_SCOPE_SELECTOR } from '../compat/mini-program-css/selectors'
 import { normalizeMiniProgramPrefixedDeclaration, removeUnsupportedMiniProgramPrefixedAtRule } from '../compat/mini-program-prefixes'
 import { normalizeTailwindcssRpxDeclaration } from '../compat/tailwindcss-rpx'
@@ -227,13 +226,10 @@ const postcssWeappTailwindcssPostPlugin: PostcssWeappTailwindcssRenamePlugin = (
     if (shouldInjectTailwindcssV4Defaults || (opts.majorVersion === 4 && usesTailwindcssV4ContentVariable(root))) {
       injectMissingTailwindcssV4Defaults(root)
     }
-    if (enableMainChunkTransforms) {
-      removeEmptyAtRules(root)
-    }
   }
 
-  p.AtRuleExit = (atRule) => {
-    if (enableMainChunkTransforms) {
+  if (enableMainChunkTransforms) {
+    p.AtRuleExit = (atRule) => {
       removeUnsupportedMiniProgramPrefixedAtRule(atRule)
       /**
        * @description 移除 property
@@ -244,6 +240,10 @@ const postcssWeappTailwindcssPostPlugin: PostcssWeappTailwindcssRenamePlugin = (
         }
         atRule.remove()
       }
+      /**
+       * 清除空节点
+       */
+      atRule.nodes?.length === 0 && atRule.remove()
     }
   }
   return p
diff --git a/packages/postcss/test/post.test.ts b/packages/postcss/test/post.test.ts
index 7f1a5f820..9d77e6d6d 100644
--- a/packages/postcss/test/post.test.ts
+++ b/packages/postcss/test/post.test.ts
@@ -1,4 +1,5 @@
 import postcss from 'postcss'
+import { createStyleHandler } from '@/handler'
 import { postcssWeappTailwindcssPostPlugin } from '@/plugins/post'
 
 describe('postcss post plugin', () => {
@@ -26,4 +27,34 @@ describe('postcss post plugin', () => {
     ]).process(rawCode)
     expect(css).toMatchSnapshot()
   })
+
+  it('preserves standalone conditional placeholders for incremental css assembly', async () => {
+    const input = '@media (min-width: 64rem) { /* incremental placeholder */ }'
+    const result = await postcss([
+      postcssWeappTailwindcssPostPlugin({
+        isMainChunk: true,
+      }),
+    ]).process(input, { from: undefined })
+
+    expect(result.css).toBe(input)
+  })
+
+  it('removes nested empty blocks after the postcss lifecycle completes', async () => {
+    const styleHandler = createStyleHandler({
+      isMainChunk: true,
+    })
+    const { css } = await styleHandler('@media (min-width: 64rem) { @supports (display: grid) {} }')
+
+    expect(css).toBe('')
+  })
+
+  it('keeps comment-only incremental placeholders after postprocessing', async () => {
+    const input = '@media (min-width: 64rem) { /* incremental placeholder */ }'
+    const styleHandler = createStyleHandler({
+      isMainChunk: true,
+    })
+    const { css } = await styleHandler(input)
+
+    expect(css).toBe(input)
+  })
 })
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
index 7a03143c8..374b7bfe3 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
@@ -71,14 +71,18 @@ export function restoreCssImportAtRules(source: string, filtered: string, file?:
 }
 
 export function removeCommentOnlyAtRules(css: string) {
-  if (!css.includes('@') || !/@[a-z-]+\b[^{};]*\{(?:\s|\/\*[\s\S]*?\*\/)*\}/i.test(css)) {
+  if (!css.includes('@') || !css.includes('{')) {
     return css
   }
   try {
     const root = postcss.parse(css)
     let changed = false
     root.walkAtRules((atRule) => {
-      if (!atRule.nodes || atRule.nodes.length === 0 || atRule.nodes.some(node => node.type !== 'comment')) {
+      if (!atRule.nodes || atRule.nodes.length === 0) {
+        return
+      }
+      const hasCss = atRule.nodes.some(node => node.type !== 'comment')
+      if (hasCss) {
         return
       }
       atRule.remove()
@@ -92,12 +96,18 @@ export function removeCommentOnlyAtRules(css: string) {
 }
 
 export function removeEmptyCssAtRules(css: string) {
-  if (!css.includes('@') || !/@[a-z-]+\b[^{};]*\{(?:\s|\/\*[\s\S]*?\*\/)*\}/i.test(css)) {
+  if (!css.includes('@') || !css.includes('{')) {
     return css
   }
   try {
     const root = postcss.parse(css)
-    return removeEmptyAtRules(root) > 0 ? root.toString() : css
+    let removed = 0
+    let passRemoved = 0
+    do {
+      passRemoved = removeEmptyAtRules(root)
+      removed += passRemoved
+    } while (passRemoved > 0)
+    return removed > 0 ? root.toString() : css
   }
   catch {
     return css
diff --git a/packages/weapp-tailwindcss/test/bundlers/vite-processed-css-cleanup.unit.test.ts b/packages/weapp-tailwindcss/test/bundlers/vite-processed-css-cleanup.unit.test.ts
new file mode 100644
index 000000000..9360a4706
--- /dev/null
+++ b/packages/weapp-tailwindcss/test/bundlers/vite-processed-css-cleanup.unit.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, it } from 'vitest'
+import { removeCommentOnlyAtRules, removeEmptyCssAtRules } from '@/bundlers/vite/processed-css-assets/cleanup'
+
+describe('vite processed css cleanup', () => {
+  it('cleans empty at-rules without backtracking on comment-rich css', () => {
+    const source = [
+      '@media screen {',
+      '/* generated token */'.repeat(25),
+      '.keep { color: red; }',
+      '}',
+      '@supports (display: grid) {}',
+    ].join('\n')
+    const startedAt = performance.now()
+
+    const css = removeEmptyCssAtRules(source)
+
+    expect(performance.now() - startedAt).toBeLessThan(1000)
+    expect(css).toContain('@media screen')
+    expect(css).toContain('.keep { color: red; }')
+    expect(css).not.toContain('@supports')
+  })
+
+  it('cleans comment-only at-rules without backtracking on comment-rich css', () => {
+    const source = [
+      '@media screen {',
+      '/* generated token */'.repeat(25),
+      '.keep { color: red; }',
+      '}',
+      '@supports (display: grid) { /* removed declarations */ }',
+    ].join('\n')
+    const startedAt = performance.now()
+
+    const css = removeCommentOnlyAtRules(source)
+
+    expect(performance.now() - startedAt).toBeLessThan(1000)
+    expect(css).toContain('@media screen')
+    expect(css).toContain('.keep { color: red; }')
+    expect(css).not.toContain('@supports')
+  })
+})

From 22c7ec6b0be55206b9a45fe40c89ade40c9b6941 Mon Sep 17 00:00:00 2001
From: ice breaker <1324318532@qq.com>
Date: Tue, 21 Jul 2026 19:19:20 +0800
Subject: [PATCH 13/13] perf(vite): gate empty at-rule parsing with linear scan

---
 .../vite/processed-css-assets/cleanup.ts      |   5 +-
 .../processed-css-assets/empty-at-rule.ts     | 104 ++++++++++++++++++
 .../vite-processed-css-cleanup.unit.test.ts   |   8 ++
 3 files changed, 115 insertions(+), 2 deletions(-)
 create mode 100644 packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/empty-at-rule.ts

diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
index 374b7bfe3..d63861081 100644
--- a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/cleanup.ts
@@ -4,6 +4,7 @@ import type { InternalUserDefinedOptions } from '@/types'
 import { isMiniProgramLocalCssImportRequest, parseTailwindCssDirectiveRequest, postcss, removeEmptyAtRules } from '@weapp-tailwindcss/postcss'
 import path from 'pathe'
 import { normalizeOutputPathKey } from '../../shared/module-graph'
+import { hasEmptyAtRuleBlockCandidate } from './empty-at-rule'
 import { appendCss, collectImportedStyleFiles, createCssAssetPipelineContext, getAssetFile, isStyleImportRequest, readAssetSource } from './markers-imports'
 import { isMiniProgramStyleOutputFile, isRootStyleOutputFile } from './style-files'
 
@@ -71,7 +72,7 @@ export function restoreCssImportAtRules(source: string, filtered: string, file?:
 }
 
 export function removeCommentOnlyAtRules(css: string) {
-  if (!css.includes('@') || !css.includes('{')) {
+  if (!hasEmptyAtRuleBlockCandidate(css)) {
     return css
   }
   try {
@@ -96,7 +97,7 @@ export function removeCommentOnlyAtRules(css: string) {
 }
 
 export function removeEmptyCssAtRules(css: string) {
-  if (!css.includes('@') || !css.includes('{')) {
+  if (!hasEmptyAtRuleBlockCandidate(css)) {
     return css
   }
   try {
diff --git a/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/empty-at-rule.ts b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/empty-at-rule.ts
new file mode 100644
index 000000000..6b0e172ca
--- /dev/null
+++ b/packages/weapp-tailwindcss/src/bundlers/vite/processed-css-assets/empty-at-rule.ts
@@ -0,0 +1,104 @@
+function isAtRuleNameCharacter(code: number) {
+  return code === 45
+    || (code >= 65 && code <= 90)
+    || (code >= 97 && code <= 122)
+}
+
+function isCssWhitespace(code: number) {
+  return code === 9 || code === 10 || code === 12 || code === 13 || code === 32
+}
+
+function findAtRuleBlockStart(css: string, start: number) {
+  let parenthesisDepth = 0
+  let quote = 0
+  let squareBracketDepth = 0
+  for (let index = start; index < css.length; index++) {
+    const code = css.charCodeAt(index)
+    if (quote !== 0) {
+      if (code === 92) {
+        index++
+      }
+      else if (code === quote) {
+        quote = 0
+      }
+      continue
+    }
+    if (code === 34 || code === 39) {
+      quote = code
+      continue
+    }
+    if (code === 92) {
+      index++
+      continue
+    }
+    if (code === 47 && css.charCodeAt(index + 1) === 42) {
+      const commentEnd = css.indexOf('*/', index + 2)
+      if (commentEnd < 0) {
+        return -1
+      }
+      index = commentEnd + 1
+      continue
+    }
+    if (code === 40) {
+      parenthesisDepth++
+      continue
+    }
+    if (code === 41 && parenthesisDepth > 0) {
+      parenthesisDepth--
+      continue
+    }
+    if (code === 91) {
+      squareBracketDepth++
+      continue
+    }
+    if (code === 93 && squareBracketDepth > 0) {
+      squareBracketDepth--
+      continue
+    }
+    if (code === 123 && parenthesisDepth === 0 && squareBracketDepth === 0) {
+      return index
+    }
+    if ((code === 59 || code === 125) && parenthesisDepth === 0 && squareBracketDepth === 0) {
+      return -1
+    }
+  }
+  return -1
+}
+
+function isEmptyAtRuleBody(css: string, blockStart: number) {
+  for (let index = blockStart + 1; index < css.length; index++) {
+    const code = css.charCodeAt(index)
+    if (isCssWhitespace(code)) {
+      continue
+    }
+    if (code === 47 && css.charCodeAt(index + 1) === 42) {
+      const commentEnd = css.indexOf('*/', index + 2)
+      if (commentEnd < 0) {
+        return false
+      }
+      index = commentEnd + 1
+      continue
+    }
+    return code === 125
+  }
+  return false
+}
+
+export function hasEmptyAtRuleBlockCandidate(css: string) {
+  let searchFrom = 0
+  while (searchFrom < css.length) {
+    const atRuleStart = css.indexOf('@', searchFrom)
+    if (atRuleStart < 0) {
+      return false
+    }
+    searchFrom = atRuleStart + 1
+    if (!isAtRuleNameCharacter(css.charCodeAt(searchFrom))) {
+      continue
+    }
+    const blockStart = findAtRuleBlockStart(css, searchFrom + 1)
+    if (blockStart >= 0 && isEmptyAtRuleBody(css, blockStart)) {
+      return true
+    }
+  }
+  return false
+}
diff --git a/packages/weapp-tailwindcss/test/bundlers/vite-processed-css-cleanup.unit.test.ts b/packages/weapp-tailwindcss/test/bundlers/vite-processed-css-cleanup.unit.test.ts
index 9360a4706..2ea3fbedd 100644
--- a/packages/weapp-tailwindcss/test/bundlers/vite-processed-css-cleanup.unit.test.ts
+++ b/packages/weapp-tailwindcss/test/bundlers/vite-processed-css-cleanup.unit.test.ts
@@ -1,7 +1,15 @@
 import { describe, expect, it } from 'vitest'
 import { removeCommentOnlyAtRules, removeEmptyCssAtRules } from '@/bundlers/vite/processed-css-assets/cleanup'
+import { hasEmptyAtRuleBlockCandidate } from '@/bundlers/vite/processed-css-assets/empty-at-rule'
 
 describe('vite processed css cleanup', () => {
+  it('detects empty block at-rules with a linear precheck', () => {
+    expect(hasEmptyAtRuleBlockCandidate('@media screen { /* token */ .keep {} }')).toBe(false)
+    expect(hasEmptyAtRuleBlockCandidate('@media screen { @supports (display: grid) { /* removed */ } }')).toBe(true)
+    expect(hasEmptyAtRuleBlockCandidate('@supports (background: url(data:image/svg+xml;utf8,test)) {}')).toBe(true)
+    expect(hasEmptyAtRuleBlockCandidate('@custom "value;{}"; .keep {}')).toBe(false)
+  })
+
   it('cleans empty at-rules without backtracking on comment-rich css', () => {
     const source = [
       '@media screen {',