use rspack instead of webpack.

package.json

@@ -5,8 +5,8 @@
     "prepare": "node scripts/prepare-private-key.js",
     "start": "node scripts/npm-start.js",
     "develop": "npm run build -- --watch",
-    "build": "npm run prepare && cross-env NODE_ENV=development webpack",
-    "build:prod": "npm run prepare && cross-env NODE_ENV=production webpack",
+    "build": "npm run prepare && cross-env NODE_ENV=development rspack build",
+    "build:prod": "npm run prepare && cross-env NODE_ENV=production rspack build",
     "dts-gen": "kintone-dts-gen",
     "lint": "eslint src --ext .js,.jsx,.ts,.tsx",
     "upload": "env-cmd --silent kintone-plugin-uploader dist/plugin.zip --watch --waiting-dialog-ms 3000"
@@ -27,33 +27,25 @@
     "tiny-invariant": "^1.3.3"
   },
   "devDependencies": {
-    "@babel/core": "^7.27.1",
-    "@babel/preset-env": "^7.27.2",
-    "@babel/preset-react": "^7.27.1",
-    "@babel/preset-typescript": "^7.27.1",
     "@cybozu/eslint-config": "^24.0.0",
     "@kintone/dts-gen": "^8.1.2",
     "@kintone/plugin-uploader": "^9.1.5",
     "@kintone/webpack-plugin-kintone-plugin": "^8.0.11",
+    "@rspack/cli": "^1.3.12",
+    "@rspack/core": "^1.3.12",
     "@shin-chan/kypes": "^0.0.7",
+    "@swc/helpers": "^0.5.17",
     "@types/file-saver": "^2.0.7",
     "@types/react": "^19.1.5",
     "@types/react-dom": "^19.1.5",
-    "ajv": "^8.17.1",
-    "babel-loader": "^10.0.0",
     "cross-env": "^7.0.3",
     "css-loader": "^7.1.2",
     "env-cmd": "^10.1.0",
     "eslint": "^9.27.0",
     "eslint-plugin-react": "^7.37.5",
     "npm-run-all": "^4.1.5",
-    "postcss-loader": "^8.1.1",
     "prettier": "^3.5.3",
-    "sass": "^1.89.0",
-    "sass-loader": "^16.0.5",
     "style-loader": "^4.0.0",
-    "typescript": "^5.8.3",
-    "webpack": "^5.99.9",
-    "webpack-cli": "^6.0.1"
+    "typescript": "^5.8.3"
   }
 }

rspack.config.js

@@ -1,4 +1,5 @@
 /* eslint-env node */
+
 const path = require('path');
 const KintonePlugin = require('@kintone/webpack-plugin-kintone-plugin');
 
@@ -18,27 +19,56 @@ module.exports = {
   module: {
     rules: [
       {
-        test: /\.[t|j]sx?$/,
-        loader: 'babel-loader',
-        exclude: /node_modules/,
+        test: /\.(j|t)s$/,
+        exclude: [/[\\/]node_modules[\\/]/],
+        loader: 'builtin:swc-loader',
         options: {
-          presets: [
-            [
-              '@babel/preset-env',
-              {
-                useBuiltIns: 'usage',
-                corejs: 3,
-                modules: false,
+          sourceMaps: !isProduction,
+          jsc: {
+            parser: {
+              syntax: 'typescript',
+            },
+            transform: {
+              react: {
+                runtime: 'automatic',
+                development: !isProduction,
               },
-            ],
-            '@babel/preset-typescript',
-            '@babel/preset-react',
-          ],
+            },
+            externalHelpers: true,
+          },
+          env: {
+            targets: 'Chrome >= 48',
+          },
         },
       },
       {
-        test: /[^\.module]\.css$/i,
-        use: ['style-loader', 'css-loader', 'postcss-loader'],
+        test: /\.(j|t)sx$/,
+        loader: 'builtin:swc-loader',
+        exclude: [/[\\/]node_modules[\\/]/],
+        options: {
+          sourceMaps: !isProduction,
+          jsc: {
+            parser: {
+              syntax: 'typescript',
+              tsx: true,
+            },
+            transform: {
+              react: {
+                runtime: 'automatic',
+                development: !isProduction,
+              },
+            },
+            externalHelpers: true,
+          },
+          env: {
+            targets: 'Chrome >= 48', // browser compatibility
+          },
+        },
+      },
+      {
+        test: /\.css$/i,
+        use: ['style-loader', 'css-loader'],
+        exclude: /\.module\.css$/,
       },
       {
         test: /\.module\.css$/i,
@@ -55,8 +85,6 @@ module.exports = {
               },
             },
           },
-          'postcss-loader',
-          'sass-loader',
         ],
       },
     ],