标签：#multiplatform

I shipped a small dev-news reader to Google Play with the entire client written in one Compose Multiplatform codebase — every screen in commonMain , no per-platform UI. This is an honest field report on what that actually costs in production: the numbers, the native seams, and the parts that still hurt (hi, iOS). The repo is open source (MIT), so everything here is checkable. TL;DR — For a content/list/detail app, CMP is comfortably production-ready on Android. 96.9% of the shared module is commonMain ; the native cost is concentrated in ~10 expect/actual seams. iOS compiles and renders, but isn't polished yet. The numbers Source set Files Lines Share commonMain 59 ~7,700 96.9% androidMain 2 123 1.6% iosMain 3 127 1.6% All 17 screens live in commonMain — trending list, aggregated feed, README detail, profile with paging, settings, favorites — and there isn't a single if (isAndroid) branch in the UI. The 3% that isn't shared The native cost isn't spread thinly across the codebase. It's concentrated in ~10 expect/actual seams, and this is the entire list: Platform info — app version, system language, User-Agent string System interaction — open URL, open app settings, share sheet Analytics — a trackEvent hook (Android → Aptabase; iOS is deliberately a no-op for now) WebView — the messy one (below) Everything that touches a platform API is small and enumerable. Everything else came for free. Why expect/actual and not an interface + DI? For these ~10 seams, expect/actual was the least ceremony: no DI wiring, and the compiler refuses to build until every target implements the declaration. The moment a seam has more than one implementation, or I'd want to fake it in tests, an interface in commonMain with injected impls is the better tool. For a fixed set of platform primitives, expect/actual wins on friction. The ugliest boundary: WebView I have two WebView paths, and I'll be precise because the repo is open: Rendering GitHub READMEs from an HTML string — inline expect/act