# service-boundary-and-native

> Claude/Codex skill by [@zakariaf](https://omgskills.com/library/zakariaf/index.md) · 61 stars · Updated 2026-09-23

Wires every side effect and native channel as an injectable interface behind a Provider that throws UnimplementedError until the composition root overrides it, with one live impl per flavor, value-typed signatures returning typed results, hand-written contract-honouring fakes over mocks, MethodChannel quarantined to one lib/native/ directory, and versioned cross-language contracts edited on both sides in one commit. Use when adding or changing a ShareService/AnalyticsService/RemoteConfigService or any side-effect port, injecting a Clock (package:clock) via clockProvider, a MethodChannel/platform channel or native widget bridge, a flavor entrypoint (main\_\*.dart) or per-flavor provider override, a shared-file/JSON contract mirrored in Kotlin/Swift, replacing a stray DateTime.now() or direct SDK call inside a widget/notifier/repository, or wiring a fake via ProviderScope(overrides:) in tests.

Tags: agent-skills, ai-agents, best-practices, claude-code, codex, coding-agent, cursor, dart, dartlang, developer-tools, drift, flutter, flutter-architecture, github-copilot, go-router, llm, material-design, mvvm, riverpod, skills

## Install

```sh
git clone https://github.com/zakariaf/Flutter-Skills /tmp/Flutter-Skills && ln -s /tmp/Flutter-Skills/skills/service-boundary-and-native ~/.claude/skills/service-boundary-and-native
```

## From README

Service boundary and native Every platform capability — reading "now", sharing, logging an event, fetching remote flags, calling a MethodChannel — crosses the app's layers as an injected interface. The interface names value types only; the concrete SDK lives in exactly one class; the composition root (main) wires one live impl; tests wire a deterministic fake. Abstract exactly what cannot run in a test — nothing more. This is the seam that keeps features pure, SDKs swappable, and the whole app testable headlessly. Read the reference for the task at hand: references/service-interface.md — typed outcomes vs bool/throw, exhaustiveness, @useResult, hand-written env-fakes, the arrow-callback Future-drop hole, single write path. references/native-channels.md — MethodChannel placement, the cross-language contract ownership table, versioned-file-vs-sharedpreferences traps, native-fast-path independence, the round-trip integrationtest.

## Links

- HTML page: https://omgskills.com/library/zakariaf/flutter-skills/skills/service-boundary-and-native/
- GitHub: https://github.com/zakariaf/Flutter-Skills
- Author: [@zakariaf](https://omgskills.com/library/zakariaf/index.md)

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