An electron-vite config which covers: multi-window, TanStack Router, generating a product.json, and using Prisma for an internal SQLite3 database. It's not clean, but it works.

electron.vite.config.ts

import typescript from "@rollup/plugin-typescript";
import {TanStackRouterVite} from "@tanstack/router-plugin/vite";
import react from "@vitejs/plugin-react";
import {defineConfig, externalizeDepsPlugin} from "electron-vite";
import {existsSync} from "fs";
import {mkdir, rm, writeFile} from "fs/promises";
import {copyFile} from "node:fs/promises";
import {resolve} from "path";
import {IProduct} from "./src/platform/product/common/product-service.interface.js";

const pkg = require("./package.json");

const product: IProduct = {
  nameShort: pkg.productName,
  nameLong: pkg.productName,
  description: pkg.description,
  applicationName: pkg.name,
  license: {
    name: pkg.license,
    url: "https://opensource.org/license/mit/",
  },
  update: {
    url: process.env.TOWER_URL!,
    channel: process.env.UPDATE_CHANNEL!,
    date: Date.now().toString(),
    version: pkg.version,
  },
  win32: {
    appUserModelId: `${String(pkg.companyNameShort).replaceAll(" ", "")}.${String(pkg.productName).replaceAll(" ", "")}`,
  },
};

// generate a product.json file using product object
const productJson = JSON.stringify(product, null, 2);

// write the product.json file to the out directory
if (existsSync("out"))
  // Might as well while we're here
  await rm("out", {recursive: true});

await mkdir("out");

await writeFile(resolve(__dirname, "out/product.json"), productJson);
// ensure we use a copy of the database during development, not copied during packaging
await copyFile(
  resolve(__dirname, `resources/${process.env["VITE_DATABASE_URL"]}`),
  resolve(__dirname, `out/${process.env["VITE_DATABASE_URL"]}`)
);

const getWindowHtml = (nameWithoutExtension: string) =>
  resolve(__dirname, "src/workbench/windows/", `${nameWithoutExtension}.html`);
const getPreloadFile = (nameWithoutExtension: string) =>
  resolve(
    __dirname,
    "src/base/electron-sandbox/",
    `${nameWithoutExtension}.preload.ts`
  );
const resourcesDirectory = resolve(__dirname, "src/resources");
const workbenchDirectory = resolve(__dirname, "src/workbench");

// @ts-ignore
export default defineConfig({
  main: {
    build: {
      outDir: resolve(__dirname, "out/main"),
      sourcemap: true,
      rollupOptions: {
        output: {
          format: "es",
        },
        input: resolve(__dirname, "src/core/electron-main/main.ts"),
      },
    },
    resolve: {
      alias: {
        ".prisma/client/default": "./node_modules/.prisma/client/default.js",
      },
    },
    // @ts-ignore
    plugins: [externalizeDepsPlugin(), typescript()],
    publicDir: resourcesDirectory,
  },
  preload: {
    build: {
      sourcemap: true,
      outDir: resolve(__dirname, "out/preload"),
      rollupOptions: {
        output: {
          format: "es",
        },
        input: [
          getPreloadFile("main"),
          getPreloadFile("registration"),
          getPreloadFile("view"),
          getPreloadFile("settings"),
        ],
      },
    },
    // @ts-ignore
    plugins: [externalizeDepsPlugin(), typescript()],
    publicDir: resourcesDirectory,
  },
  renderer: {
    root: workbenchDirectory,
    build: {
      rollupOptions: {
        input: {
          main_window: getWindowHtml("main"),
          registration_window: getWindowHtml("registration"),
          view_window: getWindowHtml("view"),
          settings_window: getWindowHtml("settings"),
        },
      },
      sourcemap: true,
      outDir: resolve(__dirname, "out/renderer"),
    },
    resolve: {
      alias: {
        "@/resources": resourcesDirectory,
        "@/workbench": workbenchDirectory,
      },
    },
    plugins: [
      react(),
      typescript(),
      // TODO this is restricted to only the settings window. Investigate multi-window approach.
      // TODO drop multi-window for internal pages (i.e about:config)
      TanStackRouterVite({
        routesDirectory: resolve(
          workbenchDirectory,
          "windows",
          "settings/routes"
        ),
        generatedRouteTree: resolve(
          workbenchDirectory,
          "windows",
          "settings/routeTree.gen.ts"
        ),
      }),
    ],
  },
});