Ktor Client for KMP and Android

This reference covers the Ktor client configuration traps — plugin install order, serialization flags, auth refresh, and error mapping — not the basics of a shared HttpClient, engine selection, or ContentNegotiation setup. Related: android-skills:android-data-layer (repository + the DataError error model — its canonical home), android-skills:android-retrofit (Android-only equivalent).

Plugin install order — HttpRequestRetry BEFORE HttpTimeout

The install order most often gotten wrong: installing HttpTimeout before HttpRequestRetry. Plugins run in install order for outgoing requests; retries must be able to catch timeout errors, so retry has to wrap timeout.

val json = Json { ignoreUnknownKeys = true; coerceInputValues = true; encodeDefaults = true }  // encodeDefaults: see the section below