feat(ui-scripts,ui-themes): generate theme tokens as css custom properties

Add a buildCSSVariables step to build-themes that flattens each theme's shared tokens and
emits one stylesheet per theme under src/themes/newThemeTokens/themesAsCSSVariables/, plus a
cssThemesWithMediaQueries.css that maps the light and dark themes to prefers-color-scheme.

Register the malva plugin in dprint.json so the generated stylesheets are formatted by the
existing dprint pass, and mark *.css as side-effectful in ui-themes so bundlers do not drop
the stylesheet imports.

Also emit SharedTokens as a type-only import in the generated component templates.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: HerrTopi

dprint.json

@@ -7,5 +7,8 @@
     "**/node_modules",
     "!packages/ui-themes/src/themes/newThemeTokens/"
   ],
-  "plugins": ["https://plugins.dprint.dev/typescript-0.95.11.wasm"]
+  "plugins": [
+    "https://plugins.dprint.dev/typescript-0.95.11.wasm",
+    "https://plugins.dprint.dev/g-plane/malva-v0.16.0.wasm"
+  ]
 }

packages/ui-scripts/lib/build/buildThemes/buildCSSVariables.ts

@@ -0,0 +1,81 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 - present Instructure, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+import { promises as fs } from 'fs'
+import path from 'path'
+import { pathToFileURL } from 'url'
+
+const importDefault = async (file: string) =>
+  (await import(pathToFileURL(file).href)).default
+
+const loadTheme = async (themePath: string) => {
+  const [primitives, semantics, sharedTokens] = await Promise.all([
+    importDefault(path.join(themePath, 'primitives.ts')),
+    importDefault(path.join(themePath, 'semantics.ts')),
+    importDefault(path.join(themePath, 'sharedTokens.ts'))
+  ])
+  return sharedTokens(semantics(primitives))
+}
+
+const flattenObj = (obj: Record<string, any>) => {
+  const result: Record<string, any> = {}
+
+  for (const i in obj) {
+    if (typeof obj[i] === 'object' && !Array.isArray(obj[i])) {
+      const temp = flattenObj(obj[i])
+      for (const j in temp) {
+        result[i + '-' + j] = temp[j]
+      }
+    } else {
+      result[i] = obj[i]
+    }
+  }
+  return result
+}
+
+const buildCSSVariables = async (targetPath: string) => {
+  const root = path.resolve(targetPath)
+  const entries = await fs.readdir(root, { withFileTypes: true })
+
+  const themeDirs = entries
+    .filter((e) => e.isDirectory() && e.name !== 'componentTypes')
+    .map((e) => e.name)
+
+  const sharedTokensByThemes: Record<string, any> = {}
+
+  for (const theme of themeDirs) {
+    const resolved = await loadTheme(path.join(root, theme))
+
+    const flatResult = flattenObj(resolved)
+    const cssVariables = Object.keys(flatResult).reduce(
+      (res, key) => `${res}--${key}:${flatResult[key]};`,
+      ''
+    )
+    sharedTokensByThemes[theme] = cssVariables
+  }
+
+  return sharedTokensByThemes
+}
+
+export default buildCSSVariables

packages/ui-scripts/lib/build/buildThemes/setupThemes.ts

@@ -33,6 +33,7 @@ import generateComponent, {
   generateComponentType
 } from './generateComponents.ts'
 import { resolveBin, runCommandAsync } from '@instructure/command-utils'
+import buildCSSVariables from './buildCSSVariables.ts'
 
 // transform to an object for easier handling
 export const transformThemes = (themes: any, input: any) =>
@@ -193,12 +194,12 @@ const setupThemes = async (targetPath: string, input: any): Promise<void> => {
           sharedTokensTypes = componentTypes
           const componentFileContent = `
 
-        import { SharedTokens } from '../commonTypes'
+        import type { SharedTokens } from '../commonTypes'
         import type { Semantics } from "./semantics"
 
         const ${fullComponentName} = (semantic: Semantics): ${capitalize(
-          fullComponentName
-        )} => ({${componentThemeVars}})
+            fullComponentName
+          )} => ({${componentThemeVars}})
         export default ${fullComponentName}
           `
 
@@ -368,6 +369,38 @@ const setupThemes = async (targetPath: string, input: any): Promise<void> => {
     }
   `
   await createFile(`${targetPath}/index.ts`, exportIndexFileContent)
+
+  // generate themes  as css variables
+  const cssVarObject = await buildCSSVariables(targetPath)
+
+  const cssThemes = Object.keys(cssVarObject)
+  for (let i = 0; i < cssThemes.length; i++) {
+    const cssTheme = cssThemes[i]
+    await createFile(
+      `${targetPath}/themesAsCSSVariables/${cssTheme}.css`,
+      `.${cssTheme}{
+      ${cssVarObject[cssTheme]}
+      }`
+    )
+  }
+
+  const cssThemesWithMediaQueries = `
+      :root {
+        color-scheme: light;
+        ${cssVarObject['light']}
+      }
+      @media (prefers-color-scheme: dark) {
+        :root {
+          color-scheme: dark;
+          ${cssVarObject['dark']}
+        }
+      }
+    `
+  await createFile(
+    `${targetPath}/themesAsCSSVariables/cssThemesWithMediaQueries.css`,
+    `${cssThemesWithMediaQueries}`
+  )
+
   try {
     const dprintBin = resolveBin('dprint')
     const { stdout, stderr } = await runCommandAsync(dprintBin, [

packages/ui-themes/package.json

@@ -35,7 +35,9 @@
   "publishConfig": {
     "access": "public"
   },
-  "sideEffects": false,
+  "sideEffects": [
+    "*.css"
+  ],
   "exports": {
     "./lib/*": "./lib/*",
     "./es/*": "./es/*",