defineConfig

defineConfig is an identity helper that gives the file full type-checking and autocomplete (it mirrors Vite's defineConfig). Like Vite, the argument may be a plain object, a promise, or a sync/async callback — the loader resolves it, so a config can do async work before returning { toolchain }:

dbx.config.ts

export default defineConfig(async () => {
    const { readFile } = await import('node:fs/promises');
    const version = (await readFile('./VERSION', 'utf-8')).trim();

    return {
        toolchain: {
            project: { name: 'acme', nodeVersion: version },
        },
    };
});