@rmc-toolkit/vite

Vite/Rollup adapter for Runtime Module Composition: injects the generated import map into a host's HTML before any module script runs, externalizes import-map-owned specifiers so Vite doesn't bundle or rewrite them, and provides defineSliceBuild() for a slice's own build config.

Install

npm install @rmc-toolkit/vite @rmc-toolkit/core vite

Quick example

Host — wire the plugin into vite.config.ts:

import { defineConfig } from "vite";
import { runtimeComposition } from "@rmc-toolkit/vite";
import { manifest } from "./runtime-composition.manifest";

export default defineConfig({
  plugins: [
    ...runtimeComposition({
      manifest,
      environment: "development",
    }),
  ],
});

runtimeComposition() returns two plugins: one that injects the generated import map into index.html, and one that tells Vite not to bundle or rewrite specifiers the import map owns.

Slice — build as an ESM library that externalizes anything the import map owns:

import { defineConfig } from "vite";
import { defineSliceBuild, createRollupExternal } from "@rmc-toolkit/vite";
import { manifest } from "./runtime-composition.manifest";

export default defineConfig(({ mode }) => {
  const sliceBuild = defineSliceBuild({ mode, devPort: 5174, sliceName: "search" });

  return mode === "development"
    ? sliceBuild
    : {
        ...sliceBuild,
        build: {
          ...sliceBuild.build,
          rollupOptions: { external: createRollupExternal(manifest) },
        },
      };
});

sliceName determines where the production build lands (dist/{sliceName}/index.mjs), matching the path convention resolveRoute()/createImportMap() already assume — a slice's build output requires no separate assembly step to match its production URL.

What's in here

• runtimeComposition — the combined host-side plugin pair (import-map injection + externalization).
• includeRuntimeImportMap, externalizeRuntimeComposition — the two plugins individually, if you need only one.
• createRollupExternal — a Rollup external function, for a slice's production build.
• defineSliceBuild — mode-aware Vite config for a slice (dev-server port, the library-build process.env.NODE_ENV fix, entry auto-detection).
• includeHostedImportMap, buildLocalImportMapScript — for serving the import map as a standalone hosted script rather than inlined into HTML (e.g. a production static-asset host), with local-dev override support.

Full signatures and behavior for every export: API Reference.

Documentation

• Getting Started — install and wire up a host + slice end to end
• API Reference
• Technical Implementation — the architecture and failure modes behind the pattern
• Multi-Framework Demo — a full, runnable reference implementation