ADR 02 · Platform runtime

One runtime for 30+ micro-frontends, via Import Maps

Share framework and platform code at runtime instead of bundling it thirty times.

Context

More than thirty micro-frontends render inside one product, built and released by different teams.

Each one needs React and a handful of shared platform libraries. Bundling them into every frontend would mean shipping the same code thirty times.

{ "imports": {
    "react":         "/runtime/react.js",
    "@platform/ui":  "/runtime/ui.js"
} }

Fig. 1 — Every micro-frontend asks for shared modules by name; one import map answers for all of them. (Illustrative.)

Option	For	Against
Bundle shared code into every app (rejected)	Simple, and fully independent.	The same framework is downloaded again and again, and versions drift apart.
Compose everything at build time (rejected)	One optimised bundle.	Teams can no longer release on their own.
Import Maps, one shared runtime (chosen)	A web standard. Shared code is downloaded once and teams still release independently.	Needs a clear contract for which versions are shared.

All micro-frontends load shared dependencies, such as React, from one platform runtime, resolved through Import Maps.