#rsbuild

rsbuild overrides or extends Rsbuild config (similar to Vite's build.rollupOptions, esbuild, etc.). It supports object (deep-merged with base) or function (full control, with helpers.merge for deep merge).

#Type and default

• Type: RsbuildConfig | ((base: RsbuildConfig, helpers?: RsbuildConfigHelpers) => RsbuildConfig | Promise<RsbuildConfig>) | undefined
• Default: Omitted → only framework base config (entry, HTML, output, manifest write are set by built-in plugins).

#Object form: deep merge

An object is deep-merged with the framework base. Use for adding or overriding fields (e.g. source.define, resolve.alias).

// addfox.config.ts
import { defineConfig } from "addfox";

export default defineConfig({
  rsbuild: {
    source: {
      define: { __APP_NAME__: JSON.stringify("my-ext") },
    },
    resolve: {
      alias: { "@": "/src" },
    },
  },
});

#Function form: full control

A function receives (base, helpers):

• base: Framework-generated Rsbuild config.
• helpers.merge(base, overrides): Deep-merge overrides into base and return.

Use when you need env, async logic, or complex conditions.

export default defineConfig({
  rsbuild(base, helpers) {
    return helpers!.merge(base, {
      source: { define: { __ENV__: JSON.stringify(process.env.NODE_ENV) } },
    });
  },
});

Async:

export default defineConfig({
  async rsbuild(base, helpers) {
    const overrides = await loadSomeConfig();
    return helpers!.merge(base, overrides);
  },
});

#Common use cases

#Notes

• The framework sets output.distPath, output.cleanDistPath, output.assetPrefix, and entry output filenames. Overriding output in rsbuild can break manifest paths; prefer incremental merge.

#Related

• plugins.